Final Report Summary - CLEANHATCH (Development and implementation of an innovative cleaning technology for marine and freshwater larval hatchery tanks in recirculating aquaculture systems)
Executive Summary:
Increased market pressures and the dangers of infection and contamination in natural environments are forcing the aquaculture industry to turn towards recirculating aquaculture systems (RAS). About 500 European hatcheries already use recirculating technologies, and this figure is expected to significantly increase in the near future as the market is showing a 10% annual growth. A major problem that recirculation technology carries, particularly when used for the delicate and susceptible early life stages of fish is the occurrence of disease. Moreover, once a pathogen has become established in the system, it is very difficult to eradicate it. For this reason, cleaning and disinfection operations are of paramount importance in hatchery RAS. At present, most hatcheries manually clean their tanks on a daily basis. As a result, hatcheries face significant expenses as a result of the man hours required for these activities.
Since having a disease-free environment is essential, the biggest concerns of any larval hatchery are biosecurity and water quality. Therefore, it is not only important that the internal surfaces of the tanks and the standpipe meshes are physically cleaned to remove biofilms, but it is also necessary to include a degree of disinfection to protect against diseases such as Vibrio sp.
At present, there is a real need in aquaculture to find a sustainable and cost-effective technology for efficient cleaning and disinfection in larval hatcheries. The current cleaning methods carry huge economic consequences. For example, farms have lower productivity and quality through reduced survival rates of cultured species due to regular bacterial outbreaks. As a result, there are lower revenues. Their maintenance costs are also very high because of regular mesh changing and man hours required for cleaning and disinfection. The current systems are not reliable as biofilms are never fully removed. Moreover, the present requirement for changing standpipe meshes up to two times per month result in the according cost and amounts of waste from discarded mesh.
The CLEANHATCH technology aims to:
1) Clean the tank's sides, base and standpipe meshes saving considerable man-hours.
2) Disinfect the surfaces and meshes through the focused injection of ozonated water where it is most needed.
3) Reduce the amount of mesh surface area required and therefore focus the mesh to the bottom part of the tank where the dirty water is primarily located and best extracted.
CLEANHATCH has resulted in numerous achievements and with some more testing and development could very well make an excellent product for the RAS market and aquaculture industry.
CLEANHATCH:
1) Has reduced cleaning related labour costs by 80%.
2) Has resulted in a 32% increase in the final weight of trout larvae.
3) Significantly reduced bacterial counts on tank surfaces.
4) Is safe and easy to operate.
5) Enables the use of a small stainless steel mesh that does not require cleaning and regular replacement.
6) Have no negative environmental impacts.
7) Operates in TRO values that are below the safety thresholds for juveniles.
8) Is economically viable with potentially huge reductions in production costs.
Further development that is foreseen includes:
1) Additional testing on marine species to determine at which stage CLEANHATCH is most suitable for use.
2) Additional testing on salmonid species to give additional value to the results already attained.
3) Testing on live feed production systems.
4) Additional testing to achieve higher disinfection.
5) Further automation for ozone control.
Project Context and Objectives:
Technological needs in larval hatcheries
The risks associated with aquaculture and increased market pressures to produce high quality and low cost produce have driven the industry to develop technologies and methods that reduce the level of risk to investors and maintain reliable production output. This is leading to a move away from more traditional 'extensive' methods of farming (ponds, lakes, etc.) that are susceptible to environmental fluctuations and the dangers of infection and contamination, and towards RAS. RAS are now widely used for both the production of marine and freshwater fry in larval hatcheries and for on-growing fingerlings to market size.
The concept of RAS is to utilise a small amount of water that is continually filtered and recycled to culture a stock of fish, with the aid a variety of technical, biotechnological and chemical devices to maintain water quality. The level of control of environmental factors within RAS has led to a considerable increase in production for a given water volume. But as with any 'intensive' rearing process, there are inherent increases in hardware investment and some risks (i.e. technologies to maintain favourable water parameters, possibility of developing disease problems, etc.). To manage these risks, the 'RAS sector' has invested heavily in devising methods that will increase stock security and performance. Especially for hatchery operations, RAS have a number of benefits in terms of quantity and cost-efficiency, but the issue of bacterial loading on such systems remains a cause of concern and a particular bottleneck in their wider application and acceptance in the market.
Despite increased levels of automation within hatchery and RAS facilities (automatic feeders; pH & O2 dosing equipment, etc.) there still remain a number of fundamental issues that require high levels of human intervention and therefore increased costs. The simple task of cleaning the internal surfaces of tanks as well as the standpipe meshes is extremely important in all RAS hatcheries and one that has endured much study and design to overcome this laborious but vital task. It is particularly important for hatcheries were water quality and control of bacteria and viruses impact more severely upon developing fish. The current methods and technologies used are far from being ideal for the high demands of a hatchery for cost-effective and efficient water quality management.
Given the aggressive nature of a variety of pathogens, maintaining water quality should form the foundation for any hatchery layout and system design. Due to the sensitivity of fish larvae to infections, such as Vibrio bacteria, the most common cause of mortality among cultured marine life, the biggest concern of any larval hatchery is biosecurity and the maintenance of water quality. Serious bacterial strikes cause high mortality rates in both live feed culture and larval tanks, resulting in higher production costs and lower income due to reduced production. Failure to maintain a pristine, disease-free environment not only endangers the hatchery operations but also seriously undermines grow-out facilities that depend on healthy fingerlings. For this reason it is not only important that the internal surfaces of the tanks and the standpipe meshes are physically cleaned to remove biofilm but it is also necessary to include a degree of disinfection to protect against diseases. To achieve sterilisation, RAS employ a number of methods to decrease the build-up of the vectors for disease and the viruses and bacteria themselves.
Studies have determined that the most effective methods of sterilisation involve the combination of using both UV treatment and ozone (O3) injection in tandem, but they also concede that system design in terms of incorporating sterilisation technologies is equally as important. Injection of O3 into the main inlet water stream is the most effective method of disinfection to reduce bacteria and viruses, but the levels of O3 must not exceed their tolerance limits. Ozone is also a potential danger to humans and a considerable investment. The larger the O3 generator used, the greater the risk and costs.
In summary, the current methods of cleaning and disinfecting larval culture tanks bring with them a number of disadvantages; economic (lower productivity and quality, higher maintenance costs, higher operation costs and lower revenues) and environmental (high mesh consumption). Thus, the current methods are far from being suitable for the high demands of the larval hatchery industry that is trying to meet an increasing demand from the EU population for high quality, healthy and safe fish products. The current lack of efficient and cost-effective cleaning technologies for larval hatchery RAS is indeed a substantial drawback for SMEs providing aquaculture technologies to customers, as the sustainable and cost-effective production of high quality fry is a must for successful aquaculture operations in an ever growing, highly competitive market.
CLEANHATCH solution
The solution to meet these substantial challenges is the development and implementation of a new cleaning technology which constantly sweeps and wipes the sides and base of the tanks as well as the meshes of the standpipe (physical cleaning) while at the same time injects ozonated water directly to the tank surfaces (disinfection). Compared to the state of the art, the new technology has the advantages of:
- Cleaning the tank's sides, base and standpipe meshes saving considerable man-hours;
- Disinfecting the surfaces and meshes through the focused injection of the ozonated water where it is most needed;
- Reducing the amount of mesh surface area required and therefore focusing the mesh to the bottom part of the tank where the dirty water is located and best extracted.
By developing a technology that precisely disinfects those areas of the tank most vulnerable to bacterial colonisation the overall performance of the disinfection process is optimised, while possibly increasing its' effectiveness and reducing the size of O3 generator necessary to disinfect the resulting smaller volume of water. As mentioned previously, Vibrio sp. are a group of bacteria which pose particular difficulties for RAS due to their resistance to disinfection. To employ a 'blanket' approach to ozonate the water column may not be possible especially in hatchery scenarios where the fish are particularly sensitive. The development of targeted disinfection to the walls of tanks where biofilm and bacteria thrive could help deal with this problem. To automate this process also increases biosecurity through removing the human interaction with the tank and reduce overhead costs. The development of such an innovative, cutting-edge cleaning technology for larval hatchery facilities has a huge potential to reach out for a new client base of more than 500 possible customers of existing hatcheries in Europe alone for the relevant SMEs.
Competitive threat and potential for European SMEs
The aquaculture sector has undergone a revolution over the last few decades and can now be regarded as a significant and innovative part of the EU economy with secure prospects. Aquaculture exists in every member state and is dominated by SMEs (90%). In 2006, 400 companies provided at least 64,000 full-time jobs in Europe including upstream and downstream activities and services. Worldwide, the sector is growing more rapidly than all other animal food-producing sectors with an average growth rate of 6.9% per year since 1970. In 2006, the EU-27 Member States produced 1.3 million tonnes of fishery products from aquaculture with a total value of about EUR 3 billion. The EU is the world leader for species like seabass, seabream, turbot and mussels with a value of currently EUR 2.5 million per year. However, in the EU, aquaculture production is declining lately by nearly 2% even though the demand for fish products is rising tremendously. The most important step to be taken in the next decade in order to turn around this negative production trend is the further development and implementation of innovative technologies to strengthen the competitive position of aquaculture technology providers and farmers alike. Breakthroughs in hatchery technologies for efficient and cost-effecting production of juveniles are also necessary.
In the EU, more than 1,000 hatcheries exist, as a market intelligence report by the AquaBioTech Group on behalf of an international hatchery feed producing client states. About one half of these existing hatcheries operate on a partial or full recirculation system, resulting in around 500 hatchery RAS in the EU for marine and freshwater species. This is a growing market with growth rates of around 10% per annum, offering an enormous potential for the future. Most of these larval hatcheries are small to medium scale, each producing up to 6 million fingerlings per year. Overall production in hatchery RAS in Europe was 391 million fingerlings in 2005. The rapid development of aquaculture in the EU and globally requires the further establishment of fish hatcheries for the mass production of juveniles. Only hatchery operations in RAS allow the production of the required numbers of fry to support the immense needs of fish farmers.
CLEANHATCH Objectives
CLEANHATCH enables the development, implementation, testing and optimisation of the new cleaning technology in larval hatcheries for the purposes of disinfection, water quality improvement and improving cost-efficiency. As the main output of the project, CLEANHATCH provides an automated technology, consisting of a frame and rotating arm, double wiper-blades for physical cleaning and for containing ozonated water for disinfection, and a motor that drives the process. The development of the CLEANHATCH system was tested at many stages to prove that each part of the technology and all parts collectively worked. Initial testing was undertaken in tanks with no animals, thus allowing for ease of access and manipulation of the technology, but ultimately progressed to testing in pilot-scale facilities with larvae and rotifers and then finally in a production-scale hatchery. Rotifers are a group of microscopic organisms and are a vital food source for larvae during the initial stages of development when they are not able to eat dry feeds.
Four species of fish were investigated during the larval trials:
1) Seabream (Sparus aurata);
2) Seabass (Dicentrarchus labrax);
3) Rainbow trout (Oncorhynchus mykiss); and
4) Turbot (Psetta maxima).
The Scientific and Technological objectives within the project were to:
1) Simulate the introduction of ozonated water to the side and bottom of larval and live feed tanks to clarify potential for reduction of Vibrio strikes with professional hydrodynamic modelling software.
2) Design and implement effective double wiper blades that sweep the sides and base of the tank for physical cleaning whilst containing highly ozonated water for disinfection.
3) Design a system with a reduced mesh to remove the dirtiest water from the bottom of the tank that does not block whilst allowing sufficient water exchange in the tank.
4) Determine performance of the overall CLEANHATCH system, including optimal rotational speed of the cleaning arm, production characteristics, water quality, cost-effectiveness, etc.
5) Design and successfully run the new CLEANHATCH system in pilot and production scale tests to achieve a flawlessly running, marketable product.
Project Results:
Overall strategy and general description
CLEANHATCH was carried out by 3 SMEs and 2 RTDs with the overall goal of developing, implementing, testing and optimising the innovative CLEANHATCH cleaning technology for hatcheries. In order to fulfil the objectives stated by the CLEANHATCH consortium, the project contained three types of activity: research and technological development (WP 1-3), other (WP 4) and management (WP 5). This work was carried out during a 28-month time frame. The diverse activities and tasks were divided into 5 work packages (WP) which were closely interconnected.
CLEANHATCH was a 'Research for SMEs' research project since the proposing SMEs (AquaBioTech Ltd., Storvik Aqua AS. and Viking Fishfarms Ltd.) could not carry out the required R&D on their own, due to the considerable research and financial resources needed. WP leadership was distributed between the two RTDs (Research Institute for Fisheries, Aquaculture and Irrigation and ttz Bremerhaven) in WP 1 and 2 whereas the SMEs led the on-site testing, dissemination and management activities (WP 3, 4, 5). The RTDs, subcontracted by SMEs, accomplished the scientific developments, whilst the SMEs were heavily involved during the testing and optimisation activities of the new cleaning technology and during the on-site testing. WPs were accomplished by all consortium members who worked together in the tasks according to their expertise and suitability.
The R&D activities were divided in three work packages. In WP1, (preparation and determination of requirements and development of evaluation criteria), partners established the basis for the pilot-scale construction of the CLEANHATCH cleaning technology by providing the scheme and first data for the final assessment of the pilot and production scale experiments in hatcheries in WP3. In addition, partners developed the design of all trials to be performed in the project. Additionally, hydrodynamic modelling of the water flows in the larval and live feed tanks on the deployment of the CLEANHATCH system was carried out to clarify unknown parameters and to optimise the design in WP2 and testing in WP3. Consequently, all the results obtained in WP1 were used in WP2 and WP3.
Based on the information and specifications gathered in WP1, in WP2, (technical development of the CLEANHATCH technology), the new cleaning technology was built, tested at bench-scale conditions and optimised. These tests were done without use of fish, thus allowing for ease of access and manipulation of the technology, prior to WP3 testing at pilot-scale in the ABT facilities and production-scale in VIKING's hatchery.
The overall objective of WP3, (further development, testing, optimisation and evaluation under real conditions), was to test the application of the new cleaning technology in pilot and production scale hatchery RAS in order to prove the advantage of this technology. In order to achieve this, several trials were run, including ozone LC50 trials for rotifers, disinfection testing using ozone, two larval trials for seabass, two for seabream, one for trout and another using turbot. Trials for seabass, seabream and trout were undertaken at pilot-scale at ABT's state-of-the-art facilities. The turbot trial was conducted at production scale in VIKING's hatchery. At the end of the WP, the evaluation of the entire system's performance demonstrated the numerous advantages of the new technology for disinfection. To ensure that the objectives were attained, ABT as the main proposer of CLEANHATCH led the WP whilst continuously supervising and advising the RTD activities of TTZ and RIFFAI.
The other activities in WP 4 ran parallel to all other WPs and were fed with information from WP1-3. WP4 was designed to ensure effective dissemination and facilitate the take-up of results by SMEs beyond the consortium. These set of activities comprised of setting up an internet platform, developing dissemination material and participating at industrial trade fairs and other events.
The management activities of WP 5 linked together all the project components and maintained communication with the REA. There was a continuous exchange between the coordinator and all consortium members to ensure that the goals and targets were achieved. Additionally, in the frame of WP5, the foreseen IPR and exploitation activities was summarised and continuously updated in a 'Plan for the use and dissemination of foreground' so as to support SMEs in using the research results to their best advantage, leading to a clear economic impact.
Description of WP results and foreground
Work Package 1 Objectives
All partners gathered during the kick-off meeting in Malta during month 1 to establish the basis for the pilot-scale construction of the CLEANHATCH cleaning technology. During the meeting the partners established the scheme and criteria for the final assessment of the pilot and production scale experiments in WP3, as well as designed all trials to be performed in the project. Later, hydrodynamic modelling of the water flows in the larval and live feed tanks, on the deployment of the new CLEANHATCH system to the tanks, was carried out to clarify unknown parameters and to optimise the design in WP2 and testing in WP3. Consequently, all results obtained in WP1 then flowed into WP2 and 3.
Task 1.1: Developing evaluation criteria for assessment
The evaluation criteria were developed to evaluate the following important aspects:
1) Economic efficiency of the cleaning technology (input, maintenance and output relationship, production of more larvae and live feed possible, investment costs of the new system, etc.).
2) Environmental efficiency (energy needs, water needs, etc.).
3) Water quality (ozone concentration, bacteria levels, pH, temperature, dissolved oxygen levels, redox potential, bromide levels, COD, BOD, etc.).
4) Larvae and live feed health (ozone tolerance of larvae (LD 50 trials), growth rate, survival rate, bacteria levels on gills, Vibrio and other disease outbreaks, deformities, number of chemotherapeutant treatments needed).
5) Other, such as work safety aspects of ozone: exposure threshold standards, regulatory considerations, material destruction, etc.
Task 1.2: Developing technical and experimental design of trials
The trial design sheets for the experiments of rotifer (Brachionus plicatilis) culture and seabream (Sparus aurata), Atlantic salmon (Salmo salar), and turbot (Psetta maxima) larviculture were prepared successfully. Later on, European seabass (Dicentrarchus labrax) was added to the test species, and rainbow trout (Oncorhynchus mykiss) replaced Atlantic salmon, and the TDSs were updated accordingly. The TDSs included details regarding the objective of each trial, the conditions used to culture the live feed and larvae, the protocol for using the CLEANHATCH technology, and the parameters that should be measured (water chemistry, microbiology, rotifer and egg counts, survival rates, growth rates, condition factors, feed conversion ratio, proportion of deformities, man-hours used, water and energy used, etc.). Possible constraints were also listed to facilitate corrective actions if necessary.
Task 1.3: Hydrodynamic modelling of water flow in tanks
For the hydrodynamic modelling TTZ used the ANSYS CFX software program. ANSYS CFX allows the simulation of the behaviour of systems, processes and equipment involving flows of liquids and gases, heat and mass transfer, chemical reactions and related physical phenomena. ANSYS CFX is integrated into the so-called ANSYS Workbench platform. The ANSYS Workbench incorporates the entire simulation process working through the system from top to bottom, starting with the integration of the original CAD geometry from most CAD software, defining the parameters for simulation to processing the analysis results.
In order to carry out the simulations, a basic construction design of the cleaning arm was made. The diameter of the nozzle feed pipe was found 18mm. First, the optimal diameter of the nozzle feed pipe was calculated. For optimal flow dynamics, the velocity of the fluid needs to be a minimum of 1ms-1.The first set of simulations was carried out considering the typical water flow rates for seabream, that is, 45l/h 180l/h. In order to test whether the different flow rates could be managed with the same frame diameter, the pressure with which the water was injected into the arm was changed between 0-4 bar for the lowest rate of 45l/h.
With this design, at flow rates of 45l/h, the simulations showed that the water does not get fully distributed throughout the arm unless additional pressure was applied. At this velocity, water was also blocked at the water inlet on top of the standpipe. Even with 2 or 4 bars of pressure, the water only went through the horizontal path. At this point, there is a clear decrease in pressure due to the rectangular design of the arm.
These first results showed that there were two major challenges to be solved in the design of the CLEANHATCH arm regarding the water flow dynamics within the arm:
1) 90° angle at water inlet on top of the standpipe before further water distribution within the arm; and
2) Internal diameter of cleaning arm of 18 mm.
Results showed that with the adjustments in the design of the cleaning arm, especially the smoothening of the rectangular angle at the water inlet, the distribution of pressure within the arm was improved. However, as the objective of even water distribution was still not reached with the minimum water flow rate, further adjustments in the design of the arm were necessary before continuing with further simulations. The following three ideas were implemented:
- Clogging the horizontal pathway of the cleaning arm to channel the water along the vertical pathway: with this concentration in one direction, water distribution could be improved and focused to the areas where water flow is needed.
- Installing a double wiper blade: by having a wiper blade on both sides of the nozzles, the blades could enclose the stream of ozonated water and lead it to flow up. Using this effect, there was no necessity to lead the water through the entire arm, but only up to the last nozzle installed.
- Installation of nozzles in 45° angle: The effect of letting the water flow up to distribute the ozonated water at the tank sides could be better used if nozzles are not in 90°, but in 45°.
Results showed that the modifications made to obtain design 3 prove right. The water flow, only directed along the standpipe, fully reached the outer parts of the cleaning arm up to the last nozzle. The ozonated water, let out at the nozzles, slowly flowed up the tanks sides, protected through the double wiper blade and supported through the 45° angle of the nozzles. Even with 30 l/h, for which the diameter of 8 mm was not optimal, and a pressure of 2 bar this could be achieved. Naturally, for the higher water flow rates of 45-180 l/h, the optimised CLEANHATCH arm also achieved the objectives.
After optimising the CLEANHATCH arm based on the findings of the previously described simulation series, the next step was to simulate the water dynamics in the tank if the CLEANHATCH arm is rotating. Hydrodynamic modelling with water flowing out of a moving source and into another water source was an extremely intricate task. In doing so, the following challenges had to be considered:
- High data processing capacity of the computers was required, with the according time needed to run the simulations; and
- Number of rotations rotations per hour.
The simulations showed that the water was distributed as needed along the tank wall surfaces. By using a larger scale and focusing on the water distribution at the nozzles, the single water streams induced by the rotating arm were better identified.
The final arm design showed that the arm is suitable for retrofitting purposes such that the water flows can easily be adjusted by fitting the nozzle pipe of suitable diameter to match the flow rates needed based of the species being cultured.
Work Package 2 Objectives
Based on the information and specifications gathered in WP1, in WP2 the new cleaning technology was designed and built, tested at bench-scale conditions and optimised. Following this, testing was undertaken at TTZ in tanks at pilot-scale with no fish, thus allowing for ease of access and manipulation of the technology during WP3 testing that was carried out in ABT's pilot-scale facilities with larvae/rotifers and then finally in the production-scale hatchery of VIKING.
Task 2.1: Design and construction of the CLEANHATCH system
Based on WP1, in this task the new cleaning technology for hatchery RAS was designed, constructed, tested and evaluated in a series of laboratory trials at bench scale at TTZ. In the design, it was decided that the new cleaning system will form an integral part of the complete hatchery system to increase survival and produce quality larvae and live feed while reducing maintenance and operating costs.
The development included a number of key issues such as:
- Gearing of the motor and its mounting on the standpipe.
- Rotation speed of the cleaning arm and the internal standpipe mesh washer.
- The type of wiper that can be used and other materials suitable for each section.
- Resistance of the materials (tank, pipes, nozzles, etc.) to ozone and OH radicals.
- The spray-bar configuration and flow rate of back-wash water.
- Water flow rates and injection of ozonated water on the wiper arm and nozzle angles to achieve maximum disinfection.
- Alternative mesh type and inter-changeable meshes of different sizes.
- Spring-loading of the bracing arms to allow for imperfections in the tank walls.
Achievements
a) Gearing: The drive system of the CLEANHATCH arm allows manipulation of the rotation speed of the arm according to the needs of the system. The drive is based on a one phase gear motor (Moment of torque: 130 Nm; 900 rpm at 50 Hz) and a frequency converter. This combination allows reducing the speed of the arm to less than one rotation per hour (rph).
b) Rotation speed: The rotation speed of conventional electric motors is proportional to the frequency of the power supply. For this reason the common rotation speed is about 900 rotations per minute (rpm). With a gearbox the rotation speed is reduced mechanically. In combination with a frequency converter, which controls the frequency of the power supply of the motor, very low rotation speeds can be reached. Moreover, the speed can be easily varied and controlled. Several tests were carried out to determine the range of rotation speeds achievable with this setup. The range found was from 0.9 rph to 8.5 rph in a tank with a maximum diameter of 1.44 m. In practice this means the lowest possible rotation speed is 0.09 rph (1 rotation in 11 hours).
c) Mechanical tests: Rubber blades and brush bristles were tested to check the mechanical cleaning effect they have. Tests were run for different thicknesses, lengths, distances to the tank surface, and number of blades used. Coloured gelatine was used to simulate the biofilm. Brushes were not suitable as they left a substantial amount of film on the tank surface while a lot of biofilm got stuck in the bristles. The best results were obtained with double rubber blades of 3 mm thickness. Tests on PVC to simulate the standpipe mesh gave poor results as the gelatine film was pressed into the mesh pores. The mesh also became crinkled and got stuck together by the gelatine film.
d) Materials: EPDM, PVC, nylon, stainless steel and PTFE were tested in terms of their resistance to ozone. Following exposure to salt water (30 ppt) at 20°C for 19 days, and ozonation for 5 minutes, 3 times a day at 7-10 g/m3 and a water flow of 2 l/min (ozone concentration of 0.8 mg/l) daily, there was no deterioration of the material observed for PVC and EPDM. Silicon, PRFE, PA and stainless steel also did not show any corrosion after treatment in fresh water at 10°C with ozone concentrations of 0.5 mg/l applied every 2 hours for 21 days.
e) Nozzle specifications: In order to cover the complete bottom and sides of the tank (taking the rotifer tank as an example), the nozzle spray width in total had to be around 680 mm (each for the bottom and for the side). With a distance between nozzles and tank wall of 50 mm, the FSE-0.6-120° nozzle has a spray width of 143 mm. With an overlap of 20 mm, this gives a total number of 6 nozzles for the nozzle holder targeted at the bottom of the tank, placed 115 mm apart.
f) Biological tests: A biofilm of Chlorophyta sp. was grown on a glass cylinder and the effect of ozone was tested on it at 12°C and 20°C, ozone concentrations of 0.1 0.2 mg/l, and contact times of 1 5 minutes. Some degree of biofilm destruction was observed with an ozone concentration of 0.2 mg/l. With other species (Spirulina platensis) no significant effects were observed. Literature studies showed that in order to achieve a 3-Log reduction of microorganisms, E. coli, Polio 1, Rotavirus, Giardia lambia, Giardia muris and Cryptosporidium required a Ct-Value (mg*min/l) with ozone of 0.02 0.1-0.2 0.006-0.06 0.5-0.6 1.8-2.0 and 3.5-10 respectively. The Ct-value is the product of the concentration of ozone supplied (mg/l) for a given time (min). A water flow of 45 l/hr. was determined to be best.
g) Meshes: A cleaning system for the standpipe mesh was designed to reduce the number of times that the mesh needs to be removed for cleaning. This consisted of nozzles and an attached wiper blade.
h) Spring-loads: Theoretically, spring-loads could be integrated into the PVC arm enabling the cleaning device adjust to non-geometric tank dimensions.
Arm Design: In order to realise the technology, the arm designed consisted of:
- A supporting frame to keep the arm centred and stable in the tank to ensure even cleaning.
- A driving mechanism to ensure the automatic moving of the arm.
- Configuration of the arm to allow retrofitting to existing systems and scaling up as simply as possible.
- A device for mechanical cleaning to achieve the physical cleaning objective.
- A steady injection of ozonated water from the arm into the tank to achieve disinfection objective.
- A system to clean the standpipe mesh to reduce the numerous mesh exchanges.
Task 2.2 Upscaling 'Dry' testing and optimisation of the CLEANHATCH system
Rubber blades: A significant problem was encountered due to the shape of the tanks. Whilst tanks appear circular, the shape is slightly distorted into an oval shape with distances from the standpipe to the tank side varying by up to 3 cm at times. The main problem with this was that in certain areas, the blades were too close to the tank whilst at others they are too far away resulting in ineffective and incomplete cleaning and leakages of highly ozonated water into the main tank water.
It was determined in task 2.1 that the best type of blade is a double system with rubber of a thickness of 3 mm. In this task, the width of the rubber blade and the distance of the supporting bar from the tank wall had to be determined. The best results were achieved when the width of the blade was adjusted to 4.5 cm whilst the distance to the tank wall was set to 4 cm.
Based on the results of the test series, the following conclusions were made:
- The arm needs to be stable and exactly centred in the middle of the tank to ensure an optimal contact pressure of the wipers against the tank walls at every spot. The supporting frame is thus essential to ensure the accurate fitting of the arm all around the tank.
- Geometrically accurate dimensions are a precondition for an automated technology as the CLEANHATCH system is envisaged to be. Only with a perfectly round tank, horizontally and vertically, and with a centralised standpipe can the mechanical cleaning be achieved in an optimal way.
- The device for mechanical cleaning could be adapted in a way that it can buffer up to 3 cm of deviations, just with adjusting the width of the wiper blades.
- Larger deviations (up to 7 cm) require a combination of measures, such as displacement pipes in case the standpipe is not centred, spring loads to automatically adjust or even wider wiper blades if possible.
- As tanks have imperfections along the walls which vary the distance to the centre of the tank, it is a challenge to mechanically clean it with the wiper blades.
- There are various possibilities to connect the wiper blade to the arm skeleton made of PVC. It is important to remember that the connection must be flexible to be able to adjust the blades to irregular tank forms and stable at the same time to ensure an optimal contact pressure of the wipers against the tank walls.
- The width of the wiper blade determines its distance to the tank walls. The longer the distance is, the more flexible the wiper blade is, allowing adjustment to irregular and bumpy tank walls.
Disinfection through ozone injection: A further series of trials and calculations were carried out regarding the targeted injection of ozonated water to disinfect the tank walls and bottom. The ozonated water is applied to the tank walls via the nozzles of the CLEANHATCH system. The distribution of the ozonated water in the tank as well as its effect depends on the set up of the nozzles, the water flow rate, the pressure with which the water is injected and the rotation of the cleaning arm. The distribution of ozonated water with and without the blades at different velocities was monitored by using coloured water and recording the waters movement on video. Tests were run at 45 l/h, 208 l/h, 480 l/h and 1,000 l/h. It was shown that:
- The injected coloured water with the lower flow rates of 45 l/h only spread slowly in the water. Without the wiper blades, it hardly reached the tank walls.
- In contrast, higher flow rates of 208 l/h and above quickly spread throughout the entire tank water, even without blades. However, the result was still better when blades were applied.
Task 3.1: Transport and installation of new cleaning system and initial tests in pilot scale testing facilities
The initial test showed some problems inherent in the pilot prototype. A lot of metal parts corroded, even when they were made from stainless steel. This was caused by the temperature and the high humidity. The conditions were in reality very different to those simulated at TTZ. Following the second and third larval trials, several modifications were required.
The first prototype had a spray bar with nozzles. These nozzles rusted very quickly and subsequently blocked. As a result, these had to be removed and ozonated water injected directly into the blades. The standpipe mesh in the experimental setup also blocked very quickly so a backwash system had to be designed. The prolonged contact between the metal parts of the arm and ozonated saline water resulted in very rapid corrosion. As a result, in the second prototype, plastic (PVC) and higher grade stainless steel parts were installed. An inability to accurately close and regulate the bottom drain disc (part of the tank) resulted in its removal during the second trial. The irregularities in the cylindrical shape of the tank meant that dirt was not entirely removed by the arm. A plastic purge strip was installed on the bottom of the tank to rectify this and collect the dirt, and an adjustable frame was installed so that the rubber blades could be better positioned against the tank wall.
In the second prototype, the standpipe backwash system was still not strong enough to unblock the small pores and so a stainless steel mesh that had a larger surface area and had a profile designed to prevent blocking was used. The wiper blades were found to not extend far enough beyond the ends of the frame, and resulted in a lot of highly ozonated water leaking into the main tank water. Prior to the fourth trial, they were extended to reach out of the water and as close to the central stand pipe as possible. In order to allow for this, the side emergency outflow was shifted to the centre above the stand pipe. The distance between each blade of the double blade system was also increased to 7 cm so as to increase the ozone contact time with the biofilm.
In addition to the modifications described above, modifications were made to the disinfection system, which was shown to be ineffective up until trial 3. The main change was the addition of an ozone system, to inject even higher levels of ozone than were injected till this point. Previously, ozone was injected in the sump tank (250-350mV) from where water was transferred to the arm. The new system consisted of a low flow-high pressure pump, a gas saturation cone and an ozoniser supplied with pure oxygen, which produced highly ozonated water that was injected into the blades of the CLEANHATCH arms. This system could reach ORP values of 800mV. To prevent the accumulation of Total Residual Oxides (TROs) an activated carbon filter was fitted to the inflow pipe of the sedimentation tank of the experimental system since activated carbon can absorb TROs.
Task 3.2: On-site pilot scale testing and optimisation of CLEANHATCH system
The on-site testing took place at the state-of-the-art facilities of ABT in Malta. The facilities include 5 self-contained and biosecure recirculation systems and a live-feed testing facility. Each tank system is completely independent and could therefore have a completely different set of rearing conditions. During the on-site tests, all partners were involved continuously. During the testing phase, partners operated and continuously evaluated the application of the new cleaning technology in the larval hatchery in order to prove the advantage of the technology.
In all, five larval trials were carried out, two with seabass, two with seabream and one with trout. In addition, LC50 ozone trials were conducted on rotifers. LC50 is a standard measure of the toxicity of the surrounding medium that will kill half of the sample population of a specific test-animal in a specified period through exposure. Furthermore, disinfection trials using ozone were conducted to better understand ways of measuring ozone and which ozone concentrations are best to use in the CLEANHATCH system. All experimental and control groups were run in triplicate and the respective statistics (ANOVA and t-test) were carried out using SPSS 13.0 for Windows. Whilst further testing is still required to achieve a fully marketable product, some very positive outcomes have been achieved as a result of WP3.
It was shown that CLEANHATCH:
- has reduced cleaning-related labour costs by 80%;
- has resulted in a 32% increase in the final weight of trout larvae';
- significantly reduced bacterial counts on tank surfaces;
- is safe and easy to operate;
- enables the use of a small metal mesh that does not require cleaning and regular replacement;
- has no negative environmental impacts;
- operates in TRO values that are below the safety thresholds; and
- is economically viable with potentially significant reductions in production costs;
During the FIRST LARVAL TRIAL, seabass larvae were used. Results from this trial included:
- No significant differences in bacterial counts, larval survival, FCR, deformities or water quality between experimental and control groups.
- The final length, weight and SGR of larvae were significantly better in the control system.
- Time required for manual cleaning of the tanks was reduced by 80%.
- Several modifications necessary to improve CLEANHATCH were highlighted.
Results of the SECOND LARVAL TRIAL (also on seabass larvae) included:
- No significant differences for larval length, weight, survival and condition factor between experimental and control groups.
- No significant differences for bacterial counts on the tank walls between experimental and control groups.
- Bacteria identified were Psuedomonas aeruginosa, Pseudomonas luteola and Pseudomonas fluoresce/putida.
- Various halogenated compounds (trihalomethanes, trihalogenacetonitriles, and haloacetates) were identified and found to be below the safe levels of 0.06 mg/l.
Results of the THIRD LARVAL TRIAL on rainbow trout in terms of larval growth were beyond the expectations of the consortium:
- Trout in the experimental system showed 32% higher weight and 6% greater length.
- FCR and survival showed no significant differences between experimental and control groups.
- No significant differences for bacterial counts on the tank walls between experimental and control groups.
Following this trial and the inability to achieve any level of measurable disinfection, several experiments using ozone were conducted to better study its disinfection capabilities, instead of relying entirely on literature.
a) Mini-trial 1 - Ozone chemistry and measurement methods
b) Mini-trial 2 ORP levels necessary to disinfect bacteria of tank surfaces
c) Mini-Trial 3 The effect of high ORP levels in the CLEANHATCH arm
Following the necessary modifications in the CLEANHATCH arm, LARVAL TRIAL FOUR using gilthead seabream was started. The results obtained were not as good as expected for the fish, but better results were obtained for disinfection:
- Final larval weight, length, survival and SGR were significantly lower in the experimental system when compared to the control system.
- When low ORPs were used (250 mV), the control tanks had lower bacterial counts indicating that the arm spreads bacteria around the tank and does not have any disinfection abilities at low ORP.
- The increased ozone level showed better disinfecting effects for the experimental system at 450 mV, 700 mV and 800 mV after using the arm compared to the control system, however results were not always significant.
Results from LARVAL trial five included:
- No significant differences in larval final length, weight, condition factor, SGR and survival during the second phase of the trial between experimental and control groups.
- Significantly lower survival in the first period of the trial (particularly in the first four days of the trial when the arm was still not switched on) indicating that the presence of the arm (or some other unknown factor) has negative effects on the larvae.
- The movement of the arm around the tank spreads bacteria around the tank surfaces to such a degree that it cancelled out the effect of the ozone completely. However if the arm rotates (using ozone) more than once a day, this issue may be overcome.
- TROs were kept below the safety threshold even at high ozone concentrations due to the use of an activated carbon filter, together with the biofilter.
Live-feed trials
Trials using batch cultured rotifers (LC50) were carried out continuously throughout WP3. Upscaling was also attempted several times, which were unfortunately unsuccessful due to culture crashes for various reasons, some of which remain unknown. Because of this, live-feed trials using the CLEANHATCH technology could not be conducted, but still several interesting results were obtained from the LC50 trials and batch culturing.
Results from this trial included:
a) Batch culture production:
- The highest rotifer production was observed at the higher temperature ranges (within the optimal) at between 27°C and 28°C with an average of up to 1,400 rotifers/ml.
- Above 28°C, (29°C and 30°C) the reproduction dynamics of the culture reduced and the water quality was also negatively affected.
- Good rotifer production (800 rotifers/ml) was observed between 24°C and 26°C but the average density was less than at higher temperatures.
- Below 24°C the average rotifer density in the batch culture was around 400 rotifers/ml and less stable.
- The highest egg production and greatest increase in rotifer density were observed between day 2 and 3. On the fourth day the population was still increasing, but this population growth was reduced in comparison with the preceding days.
b) LC50 trial:
- The average ORP value should be less than 240 mV in the rotifer culture tank.
- If high egg production is not realised at high rotifer density, or the egg production drops below 25%, the ozone value should be decreased.
- It is recommended that the amount of TROs is measured should the CLEANHATCH technology be used for rotifer production.
Task 3.3 Design of CLEANHATCH system for production scale
After the pilot scale tests a number of changes were necessary to optimise the CLEANHATCH system. During the test several factors were monitored to improve the functionality and handling of the system. In order to develop a production scale system new components were developed and some existing parts were changed. With the redesigned arm and other changes in the system most of the problems that occurred in the pilot test were solved and a more market ready system was developed. To check functionality of the improved design and to gain experience in different working conditions, production scale tests at VIKING in Scotland were planned. In task 3.3 the production scale prototype was constructed and installed ready for testing. The development of the production scale system included new CFX simulations to support the design work. The simulations were mainly focused on the calculation of the stability of the new frame. The steel frame from the first prototype was exchanged for an aluminium frame to avoid corrosion. The stability of the new frame was simulated for several tank dimensions, to ensure that the system could be applied in many different facilities. The results of the simulation showed that the stability for tanks up to a diameter of 4 m was good.
The main advantages of the redesigned system were:
- The arm was made mainly of standard readily available parts.
- The need for specially manufactured parts was reduced.
- Usage of corrosion resistant parts.
- Easy installation.
- Easy adjustment.
Task 3.4: Production Scale Testing
At VIKING's facilities, the final tests on another marine species, turbot, were undertaken in more production orientated conditions with the new CLEANHATCH prototype. Essentially, the production scale tests aimed to prove the production scale CLEANHATCH technology and ensure that the operating protocols, developed in task 3.3 were valid and applicable. It also aimed to determine whether changes needed to be made. Whilst it was planned that this task takes place after all task 3.2 was complete, it was in fact run in parallel with larval trial four in ABT. This is because turbot larvae are only available between July and August, and because task 3.2 actually finished in December (month 28). It would have therefore not been possible to run a turbot trial at that time. The trial was mainly run by VIKING with constant support from both the RTDs and SMEs.
Based on the application of the CLEANHATCH arms at the Viking Fishfarm (Ardtoe, Scotland), it can be stated that the present design of the technology is not yet a marketable product. Although the ozonated water decreased the amount of bacteria, the survival rate of larvae was not acceptable for turbot. Further improvements are needed to increase the effectiveness of the system.
The observed problems during the trials included:
- Due to the irregular walls of the tanks, the frame could not successfully maintain contact with the tank walls, resulting in ozonated water entering the fish rearing system and/or the larvae entering the ozonated area.
- During the rotation, the frame sometimes stops and 'jumps', so the ozonated water can again mix with the tank water.
- Not enough accuracy in the regulation of the ozone injection system.
The following solutions and improvements would be desirable in order to make CLEANHATCH a marketable product:
- Applying more flexible and softer blades.
- The canal which contains the ozonated water should be held against the bottom of the tank with a spring mechanism to maintain contact.
- More dynamic connection between the motor and the frame to avoid the 'jumps'.
- Applying a collection tube to the bottom of the frame outside the blades which can help to channel the ozonated water into the standpipe
Task 3.5: Overall evaluation of system performance
Based on the experiences and data gathered during the previous tasks, an overall assessment of the system performance under real testing conditions concerning all the relevant indicators developed in Task 1.1 was prepared. Keeping in mind the potential markets in the hatchery sector, results were evaluated regarding suitability of the new CLEANHATCH technology and its advantages for disinfecting and improving the overall water quality. The respective deliverable 3.9 was prepared.
Main outcomes:
1) Bacterial counts decreased at 800 mV with a rotation speed of one rotation per 3 hours; however they quickly increased again and so the arm needs to be used more than once a day.
2) The arm had no effect on general water quality parameters and TRO values remained below the safe threshold.
3) Excellent results were obtained in the trial using trout where final weight and length were 32% and 5.6% respectively higher than those seen in the control system. Additional testing is still needed to resolve whether or not the results obtained are completely due to CLEANHATCH or if other unknown factors are at play. Unfortunately, less positive results were obtained for marine larvae and therefore additional testing is required.
4) RAS reduces water exchange to only 10% over flow through or partial reuse systems. CLEANHATCH reduced this by a further 66% to require a water exchange of only 3.4% per day.
5) Energy consumption was low and so is a minor cost.
6) CLEANHATCH can result in significant potential production cost savings, particularly if used in Nordic countries where labour costs are high.
7) Materials used in CLEANHATCH are resistant to the corrosive conditions of ozonated and saline water at warm temperatures.
8) The CLEANHATCH arm can be used extremely easily after installation as it an automated system requiring minimal maintenance.
Work still to be done to reach a fully commercial stage:
1) Additional testing on marine species to determine at which stage CLEANHATCH is most suitable for use.
2) Additional testing on salmonid species to give additional value to the results already attained.
3) Testing on live feed production systems.
4) Additional testing to achieve higher disinfection.
5) Further automation for ozone control.
Potential Impact:
The impact of CLEANHATCH on the European market and its SMEs has the potential to be significant. For the reasons explained above, the industry is in need of an automated, cost-effective and reliable technology for the cleaning and disinfection of larval tanks. Thus, the commercial potential of the developed CLEANHATCH system is high, especially as the product will be able to be 'retro-fitted' to many existing systems as well as designed into new bespoke operations. Accordingly, it is expected that the new CLEANHATCH system will find significant application in European hatcheries (potential customers for ABT and STORVIK). It will allow the European hatchery industry to improve their production processes by improving the current cleaning and disinfection operations, which will ultimately lead to a drastic reduction in maintenance costs (it is estimated that hatchery operators dedicate around 40-50% of their production time to cleaning operations), reduced biosecurity risks, significant increase of productivity through higher survival rates, higher reliability of the overall system, and thus higher revenues.
ABT, having already achieved a significant share of the global RAS market, will continue to increase its market penetration in southern Europe by offering a completely new technology which has been required by the industry for years. The expected resulting new orders will be numerous. A single contract to design and supervise a hatchery construction can be worth more than EUR 250,000 with some contracts now exceeding EUR 1 million. Therefore, by acquiring a whole new range of clients through offering this new system, there will not only be the direct benefits of selling the specialist technologies (the CLEANHATCH system for larval hatchery and live feed culture) but also indirect benefits encompassing all other services included in such a contract. Clients increasingly expect full turn-key packages to conveniently cover all their requirements and so increasing the remit of services will ultimately increase competitiveness. Such a development could make ABT a market leader in designing and overseeing hatchery constructions, focussing on clients in the Mediterranean, but also in the Middle East. As a result, in relation to the amount of money that is being invested in CLEANHATCH, the company's increased sales will give a direct return over a period of approximately 6 years. By the close of the CLEANHATCH project, ABT had already won a project to develop a trout hatchery and will test the arm further in these new facilities. The results obtained in the trout trial were of key importance to this project.
In extending their product range, STORVIK, as leading technology provider for aquaculture facilities in Northern Europe, will similarly gain an enormous competitive advantage. This will establish their reputation as a global company at the forefront of aquaculture technologies. STORVIK will market the new cleaning technology with a focus on the Scandinavian countries and the UK, also including freshwater hatcheries in their portfolio. By providing their customers with the most advanced technology in the market, they will not only have a stronger presence in the Northern European market, but also the global market (in particular Canada and Chile) in the fast growing hatchery RAS market, allowing them to remain a worldwide acknowledged company at the forefront of aquaculture technology supplies. The new cleaning technology, sold as a single module, will be worth up to EUR 3,000 per system and tank, multiplying to EUR 96,000 for a typical small- to mid-sized hatchery consisting of 32 tanks.
VIKING, in providing fry of highest quality to its clients (from species such as cod, turbot or haddock), will be the first commercial hatchery profiting from the results of the CLEANHATCH project. With additional testing, VIKING will benefit from lower production costs, higher survival rates of species cultured and thus higher overall profit, enabling them to outcompete their competitors. VIKING will also profit from the new knowledge accumulated during the project, especially through the production-scale tests carried out at VIKING's facilities.
After the project termination and in accordance with the Research for SMEs scheme, the participating SMEs are now the owners of the CLEANHATCH system (both as an integrated part in new larval hatcheries and also in its specific modular parts), which was developed, tested and optimised during this project. In addition, they own the required knowledge about possible malfunctions or optimisation/decision-tree paths regarding the new technology, as well as relevant factors for the overall evaluation of the system performance.
With the on-site testing phase (WP3), the project was designed in such a way that no further technical development or demonstration activities would be required after the completion of the project to prove the efficiency and optimal performance of the CLEANHATCH system and to produce a marketable system and modules. Unfortunately, a fully marketable product was not achieved, however with some more development, this target is very realistic. The SMEs, led by ABT, can take over this final work in-house at their own R&D facilities, as the major tasks needed to be undertaken by the RTDs were almost finalised within the framework of CLEANHATCH.
CLEANHATCH will contribute to the community societal objectives by improving quality of life, health, safety and the environment. Fish farmers who upgrade their production systems will have an advantage in producing high quality, safe and healthy aquaculture products to meet the increasing health and quality requirements of consumers and European legislations. By helping complying with the EU water framework directives by improved water quality management through the CLEANHATCH system, facilities will optimise their fish production in a sustainable, safe and healthy way. The wide ranging impacts of developing this technology will help to drive the overall goals of environmental protection, water sustainability, food security and animal welfare.
Aquaculture is noted as an opportunity for economic development and re-employment particularly in the small, family managed sector. With its potential for full-time employment, it has an important role in the general stabilisation of rural areas where job opportunities are becoming increasingly limited. CLEANHATCH also addresses the objectives pointed out in the EC 6. Environment Action Programme, especially in the field of nature and biodiversity protecting a unique resource. It contributes towards minimising waste production and water pollution by chemicals by improving sterilisation of farms and adding security for local biodiversity exposed to effluents.
Moreover, different European and national legislations are addressed in the field of water and health via this project, such as the directive on economic development and re-employment (COM 2002/511), water framework directive (2000/60/EC), Groundwater Directive (80/86/EEC), policy for the regulation and control of fish diseases (Directive 91/67/EEC), animal health condition (Directive 93/53/EEC) or the wastewater treatment directive (Directive 91/271/EEC).
Dissemination Activities
Various dissemination activities were undertaken with regards to CLEANHATCH. These included:
1) A website, the development of which STORVIK was responsible for. Since the consortium does not have professional staff for web design, the task was subcontracted and launched in month 3. Amongst others, the website has the following features:
a. A distinctive domain name, http://www.cleanhatch.net/
b. Project summary, description of objectives and expected results.
c. Description of partners, contact details and links to their web pages.
d. Links to conferences and exhibitions consortium members attended.
2) A poster and flyer were created by ABT, together with STORVIK and VIKING. The material was produced in English.
3) A power point presentation was also created by ABT, STORVIK and VIKING. Similarly, the material was produced in English.
4) A list of conferences, trade and industrial fairs was drawn up. This list is continuously updated as new events are announced.
a. ABT attended European Aquaculture '10 in Portugal and Future Fish Eurasia 2010.
b. ABT, STORVIK and VIKING attended the Aqua Nor 2011 Exhibition in Norway. Here the poster was presented and flyers distributed.
c. STORVIK attended DanFish International in October 2011 and Aquaculture UK in 2012.
d. ABT and STORVIK attended Aquaculture Europe in October 2011 in Greece. A joint stand was put on display.
e. Personnel from ABT attended Aquaculture America 2012 in March 2012, and AGREme in April 2012.
f. ABT presented CLEANHATCH to the Maltese President, Dr. George Abela, and the scientific community during a presidential visit to the Malta Council of Science and Technology (MCST) on 08 March 2012.
g. All the consortium members attended Aqua2012 in Prague. The consortium meeting of September 2012 was purposely set in Prague so as to facilitate the attendance to this important exhibition. There, Dr. Jack M. James from ABT gave a presentation about the results attained.
Scientific publications have not yet been prepared as the consortium would like to conduct some additional testing prior to doing so, and also due to intellectual property rights reasons.
Project website: http://www.cleanhatch.net
Maria-Liza Scicluna
Projects Manager
AquaBioTech Group
http://www.aquabt.com
Central Complex
Naggar Street
Targa Gap, Mosta
MST 1761
Malta G.C.
Skype: mls-abtg
Mobile: +35-699-529092
Direct Line: +35-622-584114
Main Office: +35-622-584100
Increased market pressures and the dangers of infection and contamination in natural environments are forcing the aquaculture industry to turn towards recirculating aquaculture systems (RAS). About 500 European hatcheries already use recirculating technologies, and this figure is expected to significantly increase in the near future as the market is showing a 10% annual growth. A major problem that recirculation technology carries, particularly when used for the delicate and susceptible early life stages of fish is the occurrence of disease. Moreover, once a pathogen has become established in the system, it is very difficult to eradicate it. For this reason, cleaning and disinfection operations are of paramount importance in hatchery RAS. At present, most hatcheries manually clean their tanks on a daily basis. As a result, hatcheries face significant expenses as a result of the man hours required for these activities.
Since having a disease-free environment is essential, the biggest concerns of any larval hatchery are biosecurity and water quality. Therefore, it is not only important that the internal surfaces of the tanks and the standpipe meshes are physically cleaned to remove biofilms, but it is also necessary to include a degree of disinfection to protect against diseases such as Vibrio sp.
At present, there is a real need in aquaculture to find a sustainable and cost-effective technology for efficient cleaning and disinfection in larval hatcheries. The current cleaning methods carry huge economic consequences. For example, farms have lower productivity and quality through reduced survival rates of cultured species due to regular bacterial outbreaks. As a result, there are lower revenues. Their maintenance costs are also very high because of regular mesh changing and man hours required for cleaning and disinfection. The current systems are not reliable as biofilms are never fully removed. Moreover, the present requirement for changing standpipe meshes up to two times per month result in the according cost and amounts of waste from discarded mesh.
The CLEANHATCH technology aims to:
1) Clean the tank's sides, base and standpipe meshes saving considerable man-hours.
2) Disinfect the surfaces and meshes through the focused injection of ozonated water where it is most needed.
3) Reduce the amount of mesh surface area required and therefore focus the mesh to the bottom part of the tank where the dirty water is primarily located and best extracted.
CLEANHATCH has resulted in numerous achievements and with some more testing and development could very well make an excellent product for the RAS market and aquaculture industry.
CLEANHATCH:
1) Has reduced cleaning related labour costs by 80%.
2) Has resulted in a 32% increase in the final weight of trout larvae.
3) Significantly reduced bacterial counts on tank surfaces.
4) Is safe and easy to operate.
5) Enables the use of a small stainless steel mesh that does not require cleaning and regular replacement.
6) Have no negative environmental impacts.
7) Operates in TRO values that are below the safety thresholds for juveniles.
8) Is economically viable with potentially huge reductions in production costs.
Further development that is foreseen includes:
1) Additional testing on marine species to determine at which stage CLEANHATCH is most suitable for use.
2) Additional testing on salmonid species to give additional value to the results already attained.
3) Testing on live feed production systems.
4) Additional testing to achieve higher disinfection.
5) Further automation for ozone control.
Project Context and Objectives:
Technological needs in larval hatcheries
The risks associated with aquaculture and increased market pressures to produce high quality and low cost produce have driven the industry to develop technologies and methods that reduce the level of risk to investors and maintain reliable production output. This is leading to a move away from more traditional 'extensive' methods of farming (ponds, lakes, etc.) that are susceptible to environmental fluctuations and the dangers of infection and contamination, and towards RAS. RAS are now widely used for both the production of marine and freshwater fry in larval hatcheries and for on-growing fingerlings to market size.
The concept of RAS is to utilise a small amount of water that is continually filtered and recycled to culture a stock of fish, with the aid a variety of technical, biotechnological and chemical devices to maintain water quality. The level of control of environmental factors within RAS has led to a considerable increase in production for a given water volume. But as with any 'intensive' rearing process, there are inherent increases in hardware investment and some risks (i.e. technologies to maintain favourable water parameters, possibility of developing disease problems, etc.). To manage these risks, the 'RAS sector' has invested heavily in devising methods that will increase stock security and performance. Especially for hatchery operations, RAS have a number of benefits in terms of quantity and cost-efficiency, but the issue of bacterial loading on such systems remains a cause of concern and a particular bottleneck in their wider application and acceptance in the market.
Despite increased levels of automation within hatchery and RAS facilities (automatic feeders; pH & O2 dosing equipment, etc.) there still remain a number of fundamental issues that require high levels of human intervention and therefore increased costs. The simple task of cleaning the internal surfaces of tanks as well as the standpipe meshes is extremely important in all RAS hatcheries and one that has endured much study and design to overcome this laborious but vital task. It is particularly important for hatcheries were water quality and control of bacteria and viruses impact more severely upon developing fish. The current methods and technologies used are far from being ideal for the high demands of a hatchery for cost-effective and efficient water quality management.
Given the aggressive nature of a variety of pathogens, maintaining water quality should form the foundation for any hatchery layout and system design. Due to the sensitivity of fish larvae to infections, such as Vibrio bacteria, the most common cause of mortality among cultured marine life, the biggest concern of any larval hatchery is biosecurity and the maintenance of water quality. Serious bacterial strikes cause high mortality rates in both live feed culture and larval tanks, resulting in higher production costs and lower income due to reduced production. Failure to maintain a pristine, disease-free environment not only endangers the hatchery operations but also seriously undermines grow-out facilities that depend on healthy fingerlings. For this reason it is not only important that the internal surfaces of the tanks and the standpipe meshes are physically cleaned to remove biofilm but it is also necessary to include a degree of disinfection to protect against diseases. To achieve sterilisation, RAS employ a number of methods to decrease the build-up of the vectors for disease and the viruses and bacteria themselves.
Studies have determined that the most effective methods of sterilisation involve the combination of using both UV treatment and ozone (O3) injection in tandem, but they also concede that system design in terms of incorporating sterilisation technologies is equally as important. Injection of O3 into the main inlet water stream is the most effective method of disinfection to reduce bacteria and viruses, but the levels of O3 must not exceed their tolerance limits. Ozone is also a potential danger to humans and a considerable investment. The larger the O3 generator used, the greater the risk and costs.
In summary, the current methods of cleaning and disinfecting larval culture tanks bring with them a number of disadvantages; economic (lower productivity and quality, higher maintenance costs, higher operation costs and lower revenues) and environmental (high mesh consumption). Thus, the current methods are far from being suitable for the high demands of the larval hatchery industry that is trying to meet an increasing demand from the EU population for high quality, healthy and safe fish products. The current lack of efficient and cost-effective cleaning technologies for larval hatchery RAS is indeed a substantial drawback for SMEs providing aquaculture technologies to customers, as the sustainable and cost-effective production of high quality fry is a must for successful aquaculture operations in an ever growing, highly competitive market.
CLEANHATCH solution
The solution to meet these substantial challenges is the development and implementation of a new cleaning technology which constantly sweeps and wipes the sides and base of the tanks as well as the meshes of the standpipe (physical cleaning) while at the same time injects ozonated water directly to the tank surfaces (disinfection). Compared to the state of the art, the new technology has the advantages of:
- Cleaning the tank's sides, base and standpipe meshes saving considerable man-hours;
- Disinfecting the surfaces and meshes through the focused injection of the ozonated water where it is most needed;
- Reducing the amount of mesh surface area required and therefore focusing the mesh to the bottom part of the tank where the dirty water is located and best extracted.
By developing a technology that precisely disinfects those areas of the tank most vulnerable to bacterial colonisation the overall performance of the disinfection process is optimised, while possibly increasing its' effectiveness and reducing the size of O3 generator necessary to disinfect the resulting smaller volume of water. As mentioned previously, Vibrio sp. are a group of bacteria which pose particular difficulties for RAS due to their resistance to disinfection. To employ a 'blanket' approach to ozonate the water column may not be possible especially in hatchery scenarios where the fish are particularly sensitive. The development of targeted disinfection to the walls of tanks where biofilm and bacteria thrive could help deal with this problem. To automate this process also increases biosecurity through removing the human interaction with the tank and reduce overhead costs. The development of such an innovative, cutting-edge cleaning technology for larval hatchery facilities has a huge potential to reach out for a new client base of more than 500 possible customers of existing hatcheries in Europe alone for the relevant SMEs.
Competitive threat and potential for European SMEs
The aquaculture sector has undergone a revolution over the last few decades and can now be regarded as a significant and innovative part of the EU economy with secure prospects. Aquaculture exists in every member state and is dominated by SMEs (90%). In 2006, 400 companies provided at least 64,000 full-time jobs in Europe including upstream and downstream activities and services. Worldwide, the sector is growing more rapidly than all other animal food-producing sectors with an average growth rate of 6.9% per year since 1970. In 2006, the EU-27 Member States produced 1.3 million tonnes of fishery products from aquaculture with a total value of about EUR 3 billion. The EU is the world leader for species like seabass, seabream, turbot and mussels with a value of currently EUR 2.5 million per year. However, in the EU, aquaculture production is declining lately by nearly 2% even though the demand for fish products is rising tremendously. The most important step to be taken in the next decade in order to turn around this negative production trend is the further development and implementation of innovative technologies to strengthen the competitive position of aquaculture technology providers and farmers alike. Breakthroughs in hatchery technologies for efficient and cost-effecting production of juveniles are also necessary.
In the EU, more than 1,000 hatcheries exist, as a market intelligence report by the AquaBioTech Group on behalf of an international hatchery feed producing client states. About one half of these existing hatcheries operate on a partial or full recirculation system, resulting in around 500 hatchery RAS in the EU for marine and freshwater species. This is a growing market with growth rates of around 10% per annum, offering an enormous potential for the future. Most of these larval hatcheries are small to medium scale, each producing up to 6 million fingerlings per year. Overall production in hatchery RAS in Europe was 391 million fingerlings in 2005. The rapid development of aquaculture in the EU and globally requires the further establishment of fish hatcheries for the mass production of juveniles. Only hatchery operations in RAS allow the production of the required numbers of fry to support the immense needs of fish farmers.
CLEANHATCH Objectives
CLEANHATCH enables the development, implementation, testing and optimisation of the new cleaning technology in larval hatcheries for the purposes of disinfection, water quality improvement and improving cost-efficiency. As the main output of the project, CLEANHATCH provides an automated technology, consisting of a frame and rotating arm, double wiper-blades for physical cleaning and for containing ozonated water for disinfection, and a motor that drives the process. The development of the CLEANHATCH system was tested at many stages to prove that each part of the technology and all parts collectively worked. Initial testing was undertaken in tanks with no animals, thus allowing for ease of access and manipulation of the technology, but ultimately progressed to testing in pilot-scale facilities with larvae and rotifers and then finally in a production-scale hatchery. Rotifers are a group of microscopic organisms and are a vital food source for larvae during the initial stages of development when they are not able to eat dry feeds.
Four species of fish were investigated during the larval trials:
1) Seabream (Sparus aurata);
2) Seabass (Dicentrarchus labrax);
3) Rainbow trout (Oncorhynchus mykiss); and
4) Turbot (Psetta maxima).
The Scientific and Technological objectives within the project were to:
1) Simulate the introduction of ozonated water to the side and bottom of larval and live feed tanks to clarify potential for reduction of Vibrio strikes with professional hydrodynamic modelling software.
2) Design and implement effective double wiper blades that sweep the sides and base of the tank for physical cleaning whilst containing highly ozonated water for disinfection.
3) Design a system with a reduced mesh to remove the dirtiest water from the bottom of the tank that does not block whilst allowing sufficient water exchange in the tank.
4) Determine performance of the overall CLEANHATCH system, including optimal rotational speed of the cleaning arm, production characteristics, water quality, cost-effectiveness, etc.
5) Design and successfully run the new CLEANHATCH system in pilot and production scale tests to achieve a flawlessly running, marketable product.
Project Results:
Overall strategy and general description
CLEANHATCH was carried out by 3 SMEs and 2 RTDs with the overall goal of developing, implementing, testing and optimising the innovative CLEANHATCH cleaning technology for hatcheries. In order to fulfil the objectives stated by the CLEANHATCH consortium, the project contained three types of activity: research and technological development (WP 1-3), other (WP 4) and management (WP 5). This work was carried out during a 28-month time frame. The diverse activities and tasks were divided into 5 work packages (WP) which were closely interconnected.
CLEANHATCH was a 'Research for SMEs' research project since the proposing SMEs (AquaBioTech Ltd., Storvik Aqua AS. and Viking Fishfarms Ltd.) could not carry out the required R&D on their own, due to the considerable research and financial resources needed. WP leadership was distributed between the two RTDs (Research Institute for Fisheries, Aquaculture and Irrigation and ttz Bremerhaven) in WP 1 and 2 whereas the SMEs led the on-site testing, dissemination and management activities (WP 3, 4, 5). The RTDs, subcontracted by SMEs, accomplished the scientific developments, whilst the SMEs were heavily involved during the testing and optimisation activities of the new cleaning technology and during the on-site testing. WPs were accomplished by all consortium members who worked together in the tasks according to their expertise and suitability.
The R&D activities were divided in three work packages. In WP1, (preparation and determination of requirements and development of evaluation criteria), partners established the basis for the pilot-scale construction of the CLEANHATCH cleaning technology by providing the scheme and first data for the final assessment of the pilot and production scale experiments in hatcheries in WP3. In addition, partners developed the design of all trials to be performed in the project. Additionally, hydrodynamic modelling of the water flows in the larval and live feed tanks on the deployment of the CLEANHATCH system was carried out to clarify unknown parameters and to optimise the design in WP2 and testing in WP3. Consequently, all the results obtained in WP1 were used in WP2 and WP3.
Based on the information and specifications gathered in WP1, in WP2, (technical development of the CLEANHATCH technology), the new cleaning technology was built, tested at bench-scale conditions and optimised. These tests were done without use of fish, thus allowing for ease of access and manipulation of the technology, prior to WP3 testing at pilot-scale in the ABT facilities and production-scale in VIKING's hatchery.
The overall objective of WP3, (further development, testing, optimisation and evaluation under real conditions), was to test the application of the new cleaning technology in pilot and production scale hatchery RAS in order to prove the advantage of this technology. In order to achieve this, several trials were run, including ozone LC50 trials for rotifers, disinfection testing using ozone, two larval trials for seabass, two for seabream, one for trout and another using turbot. Trials for seabass, seabream and trout were undertaken at pilot-scale at ABT's state-of-the-art facilities. The turbot trial was conducted at production scale in VIKING's hatchery. At the end of the WP, the evaluation of the entire system's performance demonstrated the numerous advantages of the new technology for disinfection. To ensure that the objectives were attained, ABT as the main proposer of CLEANHATCH led the WP whilst continuously supervising and advising the RTD activities of TTZ and RIFFAI.
The other activities in WP 4 ran parallel to all other WPs and were fed with information from WP1-3. WP4 was designed to ensure effective dissemination and facilitate the take-up of results by SMEs beyond the consortium. These set of activities comprised of setting up an internet platform, developing dissemination material and participating at industrial trade fairs and other events.
The management activities of WP 5 linked together all the project components and maintained communication with the REA. There was a continuous exchange between the coordinator and all consortium members to ensure that the goals and targets were achieved. Additionally, in the frame of WP5, the foreseen IPR and exploitation activities was summarised and continuously updated in a 'Plan for the use and dissemination of foreground' so as to support SMEs in using the research results to their best advantage, leading to a clear economic impact.
Description of WP results and foreground
Work Package 1 Objectives
All partners gathered during the kick-off meeting in Malta during month 1 to establish the basis for the pilot-scale construction of the CLEANHATCH cleaning technology. During the meeting the partners established the scheme and criteria for the final assessment of the pilot and production scale experiments in WP3, as well as designed all trials to be performed in the project. Later, hydrodynamic modelling of the water flows in the larval and live feed tanks, on the deployment of the new CLEANHATCH system to the tanks, was carried out to clarify unknown parameters and to optimise the design in WP2 and testing in WP3. Consequently, all results obtained in WP1 then flowed into WP2 and 3.
Task 1.1: Developing evaluation criteria for assessment
The evaluation criteria were developed to evaluate the following important aspects:
1) Economic efficiency of the cleaning technology (input, maintenance and output relationship, production of more larvae and live feed possible, investment costs of the new system, etc.).
2) Environmental efficiency (energy needs, water needs, etc.).
3) Water quality (ozone concentration, bacteria levels, pH, temperature, dissolved oxygen levels, redox potential, bromide levels, COD, BOD, etc.).
4) Larvae and live feed health (ozone tolerance of larvae (LD 50 trials), growth rate, survival rate, bacteria levels on gills, Vibrio and other disease outbreaks, deformities, number of chemotherapeutant treatments needed).
5) Other, such as work safety aspects of ozone: exposure threshold standards, regulatory considerations, material destruction, etc.
Task 1.2: Developing technical and experimental design of trials
The trial design sheets for the experiments of rotifer (Brachionus plicatilis) culture and seabream (Sparus aurata), Atlantic salmon (Salmo salar), and turbot (Psetta maxima) larviculture were prepared successfully. Later on, European seabass (Dicentrarchus labrax) was added to the test species, and rainbow trout (Oncorhynchus mykiss) replaced Atlantic salmon, and the TDSs were updated accordingly. The TDSs included details regarding the objective of each trial, the conditions used to culture the live feed and larvae, the protocol for using the CLEANHATCH technology, and the parameters that should be measured (water chemistry, microbiology, rotifer and egg counts, survival rates, growth rates, condition factors, feed conversion ratio, proportion of deformities, man-hours used, water and energy used, etc.). Possible constraints were also listed to facilitate corrective actions if necessary.
Task 1.3: Hydrodynamic modelling of water flow in tanks
For the hydrodynamic modelling TTZ used the ANSYS CFX software program. ANSYS CFX allows the simulation of the behaviour of systems, processes and equipment involving flows of liquids and gases, heat and mass transfer, chemical reactions and related physical phenomena. ANSYS CFX is integrated into the so-called ANSYS Workbench platform. The ANSYS Workbench incorporates the entire simulation process working through the system from top to bottom, starting with the integration of the original CAD geometry from most CAD software, defining the parameters for simulation to processing the analysis results.
In order to carry out the simulations, a basic construction design of the cleaning arm was made. The diameter of the nozzle feed pipe was found 18mm. First, the optimal diameter of the nozzle feed pipe was calculated. For optimal flow dynamics, the velocity of the fluid needs to be a minimum of 1ms-1.The first set of simulations was carried out considering the typical water flow rates for seabream, that is, 45l/h 180l/h. In order to test whether the different flow rates could be managed with the same frame diameter, the pressure with which the water was injected into the arm was changed between 0-4 bar for the lowest rate of 45l/h.
With this design, at flow rates of 45l/h, the simulations showed that the water does not get fully distributed throughout the arm unless additional pressure was applied. At this velocity, water was also blocked at the water inlet on top of the standpipe. Even with 2 or 4 bars of pressure, the water only went through the horizontal path. At this point, there is a clear decrease in pressure due to the rectangular design of the arm.
These first results showed that there were two major challenges to be solved in the design of the CLEANHATCH arm regarding the water flow dynamics within the arm:
1) 90° angle at water inlet on top of the standpipe before further water distribution within the arm; and
2) Internal diameter of cleaning arm of 18 mm.
Results showed that with the adjustments in the design of the cleaning arm, especially the smoothening of the rectangular angle at the water inlet, the distribution of pressure within the arm was improved. However, as the objective of even water distribution was still not reached with the minimum water flow rate, further adjustments in the design of the arm were necessary before continuing with further simulations. The following three ideas were implemented:
- Clogging the horizontal pathway of the cleaning arm to channel the water along the vertical pathway: with this concentration in one direction, water distribution could be improved and focused to the areas where water flow is needed.
- Installing a double wiper blade: by having a wiper blade on both sides of the nozzles, the blades could enclose the stream of ozonated water and lead it to flow up. Using this effect, there was no necessity to lead the water through the entire arm, but only up to the last nozzle installed.
- Installation of nozzles in 45° angle: The effect of letting the water flow up to distribute the ozonated water at the tank sides could be better used if nozzles are not in 90°, but in 45°.
Results showed that the modifications made to obtain design 3 prove right. The water flow, only directed along the standpipe, fully reached the outer parts of the cleaning arm up to the last nozzle. The ozonated water, let out at the nozzles, slowly flowed up the tanks sides, protected through the double wiper blade and supported through the 45° angle of the nozzles. Even with 30 l/h, for which the diameter of 8 mm was not optimal, and a pressure of 2 bar this could be achieved. Naturally, for the higher water flow rates of 45-180 l/h, the optimised CLEANHATCH arm also achieved the objectives.
After optimising the CLEANHATCH arm based on the findings of the previously described simulation series, the next step was to simulate the water dynamics in the tank if the CLEANHATCH arm is rotating. Hydrodynamic modelling with water flowing out of a moving source and into another water source was an extremely intricate task. In doing so, the following challenges had to be considered:
- High data processing capacity of the computers was required, with the according time needed to run the simulations; and
- Number of rotations rotations per hour.
The simulations showed that the water was distributed as needed along the tank wall surfaces. By using a larger scale and focusing on the water distribution at the nozzles, the single water streams induced by the rotating arm were better identified.
The final arm design showed that the arm is suitable for retrofitting purposes such that the water flows can easily be adjusted by fitting the nozzle pipe of suitable diameter to match the flow rates needed based of the species being cultured.
Work Package 2 Objectives
Based on the information and specifications gathered in WP1, in WP2 the new cleaning technology was designed and built, tested at bench-scale conditions and optimised. Following this, testing was undertaken at TTZ in tanks at pilot-scale with no fish, thus allowing for ease of access and manipulation of the technology during WP3 testing that was carried out in ABT's pilot-scale facilities with larvae/rotifers and then finally in the production-scale hatchery of VIKING.
Task 2.1: Design and construction of the CLEANHATCH system
Based on WP1, in this task the new cleaning technology for hatchery RAS was designed, constructed, tested and evaluated in a series of laboratory trials at bench scale at TTZ. In the design, it was decided that the new cleaning system will form an integral part of the complete hatchery system to increase survival and produce quality larvae and live feed while reducing maintenance and operating costs.
The development included a number of key issues such as:
- Gearing of the motor and its mounting on the standpipe.
- Rotation speed of the cleaning arm and the internal standpipe mesh washer.
- The type of wiper that can be used and other materials suitable for each section.
- Resistance of the materials (tank, pipes, nozzles, etc.) to ozone and OH radicals.
- The spray-bar configuration and flow rate of back-wash water.
- Water flow rates and injection of ozonated water on the wiper arm and nozzle angles to achieve maximum disinfection.
- Alternative mesh type and inter-changeable meshes of different sizes.
- Spring-loading of the bracing arms to allow for imperfections in the tank walls.
Achievements
a) Gearing: The drive system of the CLEANHATCH arm allows manipulation of the rotation speed of the arm according to the needs of the system. The drive is based on a one phase gear motor (Moment of torque: 130 Nm; 900 rpm at 50 Hz) and a frequency converter. This combination allows reducing the speed of the arm to less than one rotation per hour (rph).
b) Rotation speed: The rotation speed of conventional electric motors is proportional to the frequency of the power supply. For this reason the common rotation speed is about 900 rotations per minute (rpm). With a gearbox the rotation speed is reduced mechanically. In combination with a frequency converter, which controls the frequency of the power supply of the motor, very low rotation speeds can be reached. Moreover, the speed can be easily varied and controlled. Several tests were carried out to determine the range of rotation speeds achievable with this setup. The range found was from 0.9 rph to 8.5 rph in a tank with a maximum diameter of 1.44 m. In practice this means the lowest possible rotation speed is 0.09 rph (1 rotation in 11 hours).
c) Mechanical tests: Rubber blades and brush bristles were tested to check the mechanical cleaning effect they have. Tests were run for different thicknesses, lengths, distances to the tank surface, and number of blades used. Coloured gelatine was used to simulate the biofilm. Brushes were not suitable as they left a substantial amount of film on the tank surface while a lot of biofilm got stuck in the bristles. The best results were obtained with double rubber blades of 3 mm thickness. Tests on PVC to simulate the standpipe mesh gave poor results as the gelatine film was pressed into the mesh pores. The mesh also became crinkled and got stuck together by the gelatine film.
d) Materials: EPDM, PVC, nylon, stainless steel and PTFE were tested in terms of their resistance to ozone. Following exposure to salt water (30 ppt) at 20°C for 19 days, and ozonation for 5 minutes, 3 times a day at 7-10 g/m3 and a water flow of 2 l/min (ozone concentration of 0.8 mg/l) daily, there was no deterioration of the material observed for PVC and EPDM. Silicon, PRFE, PA and stainless steel also did not show any corrosion after treatment in fresh water at 10°C with ozone concentrations of 0.5 mg/l applied every 2 hours for 21 days.
e) Nozzle specifications: In order to cover the complete bottom and sides of the tank (taking the rotifer tank as an example), the nozzle spray width in total had to be around 680 mm (each for the bottom and for the side). With a distance between nozzles and tank wall of 50 mm, the FSE-0.6-120° nozzle has a spray width of 143 mm. With an overlap of 20 mm, this gives a total number of 6 nozzles for the nozzle holder targeted at the bottom of the tank, placed 115 mm apart.
f) Biological tests: A biofilm of Chlorophyta sp. was grown on a glass cylinder and the effect of ozone was tested on it at 12°C and 20°C, ozone concentrations of 0.1 0.2 mg/l, and contact times of 1 5 minutes. Some degree of biofilm destruction was observed with an ozone concentration of 0.2 mg/l. With other species (Spirulina platensis) no significant effects were observed. Literature studies showed that in order to achieve a 3-Log reduction of microorganisms, E. coli, Polio 1, Rotavirus, Giardia lambia, Giardia muris and Cryptosporidium required a Ct-Value (mg*min/l) with ozone of 0.02 0.1-0.2 0.006-0.06 0.5-0.6 1.8-2.0 and 3.5-10 respectively. The Ct-value is the product of the concentration of ozone supplied (mg/l) for a given time (min). A water flow of 45 l/hr. was determined to be best.
g) Meshes: A cleaning system for the standpipe mesh was designed to reduce the number of times that the mesh needs to be removed for cleaning. This consisted of nozzles and an attached wiper blade.
h) Spring-loads: Theoretically, spring-loads could be integrated into the PVC arm enabling the cleaning device adjust to non-geometric tank dimensions.
Arm Design: In order to realise the technology, the arm designed consisted of:
- A supporting frame to keep the arm centred and stable in the tank to ensure even cleaning.
- A driving mechanism to ensure the automatic moving of the arm.
- Configuration of the arm to allow retrofitting to existing systems and scaling up as simply as possible.
- A device for mechanical cleaning to achieve the physical cleaning objective.
- A steady injection of ozonated water from the arm into the tank to achieve disinfection objective.
- A system to clean the standpipe mesh to reduce the numerous mesh exchanges.
Task 2.2 Upscaling 'Dry' testing and optimisation of the CLEANHATCH system
Rubber blades: A significant problem was encountered due to the shape of the tanks. Whilst tanks appear circular, the shape is slightly distorted into an oval shape with distances from the standpipe to the tank side varying by up to 3 cm at times. The main problem with this was that in certain areas, the blades were too close to the tank whilst at others they are too far away resulting in ineffective and incomplete cleaning and leakages of highly ozonated water into the main tank water.
It was determined in task 2.1 that the best type of blade is a double system with rubber of a thickness of 3 mm. In this task, the width of the rubber blade and the distance of the supporting bar from the tank wall had to be determined. The best results were achieved when the width of the blade was adjusted to 4.5 cm whilst the distance to the tank wall was set to 4 cm.
Based on the results of the test series, the following conclusions were made:
- The arm needs to be stable and exactly centred in the middle of the tank to ensure an optimal contact pressure of the wipers against the tank walls at every spot. The supporting frame is thus essential to ensure the accurate fitting of the arm all around the tank.
- Geometrically accurate dimensions are a precondition for an automated technology as the CLEANHATCH system is envisaged to be. Only with a perfectly round tank, horizontally and vertically, and with a centralised standpipe can the mechanical cleaning be achieved in an optimal way.
- The device for mechanical cleaning could be adapted in a way that it can buffer up to 3 cm of deviations, just with adjusting the width of the wiper blades.
- Larger deviations (up to 7 cm) require a combination of measures, such as displacement pipes in case the standpipe is not centred, spring loads to automatically adjust or even wider wiper blades if possible.
- As tanks have imperfections along the walls which vary the distance to the centre of the tank, it is a challenge to mechanically clean it with the wiper blades.
- There are various possibilities to connect the wiper blade to the arm skeleton made of PVC. It is important to remember that the connection must be flexible to be able to adjust the blades to irregular tank forms and stable at the same time to ensure an optimal contact pressure of the wipers against the tank walls.
- The width of the wiper blade determines its distance to the tank walls. The longer the distance is, the more flexible the wiper blade is, allowing adjustment to irregular and bumpy tank walls.
Disinfection through ozone injection: A further series of trials and calculations were carried out regarding the targeted injection of ozonated water to disinfect the tank walls and bottom. The ozonated water is applied to the tank walls via the nozzles of the CLEANHATCH system. The distribution of the ozonated water in the tank as well as its effect depends on the set up of the nozzles, the water flow rate, the pressure with which the water is injected and the rotation of the cleaning arm. The distribution of ozonated water with and without the blades at different velocities was monitored by using coloured water and recording the waters movement on video. Tests were run at 45 l/h, 208 l/h, 480 l/h and 1,000 l/h. It was shown that:
- The injected coloured water with the lower flow rates of 45 l/h only spread slowly in the water. Without the wiper blades, it hardly reached the tank walls.
- In contrast, higher flow rates of 208 l/h and above quickly spread throughout the entire tank water, even without blades. However, the result was still better when blades were applied.
Task 3.1: Transport and installation of new cleaning system and initial tests in pilot scale testing facilities
The initial test showed some problems inherent in the pilot prototype. A lot of metal parts corroded, even when they were made from stainless steel. This was caused by the temperature and the high humidity. The conditions were in reality very different to those simulated at TTZ. Following the second and third larval trials, several modifications were required.
The first prototype had a spray bar with nozzles. These nozzles rusted very quickly and subsequently blocked. As a result, these had to be removed and ozonated water injected directly into the blades. The standpipe mesh in the experimental setup also blocked very quickly so a backwash system had to be designed. The prolonged contact between the metal parts of the arm and ozonated saline water resulted in very rapid corrosion. As a result, in the second prototype, plastic (PVC) and higher grade stainless steel parts were installed. An inability to accurately close and regulate the bottom drain disc (part of the tank) resulted in its removal during the second trial. The irregularities in the cylindrical shape of the tank meant that dirt was not entirely removed by the arm. A plastic purge strip was installed on the bottom of the tank to rectify this and collect the dirt, and an adjustable frame was installed so that the rubber blades could be better positioned against the tank wall.
In the second prototype, the standpipe backwash system was still not strong enough to unblock the small pores and so a stainless steel mesh that had a larger surface area and had a profile designed to prevent blocking was used. The wiper blades were found to not extend far enough beyond the ends of the frame, and resulted in a lot of highly ozonated water leaking into the main tank water. Prior to the fourth trial, they were extended to reach out of the water and as close to the central stand pipe as possible. In order to allow for this, the side emergency outflow was shifted to the centre above the stand pipe. The distance between each blade of the double blade system was also increased to 7 cm so as to increase the ozone contact time with the biofilm.
In addition to the modifications described above, modifications were made to the disinfection system, which was shown to be ineffective up until trial 3. The main change was the addition of an ozone system, to inject even higher levels of ozone than were injected till this point. Previously, ozone was injected in the sump tank (250-350mV) from where water was transferred to the arm. The new system consisted of a low flow-high pressure pump, a gas saturation cone and an ozoniser supplied with pure oxygen, which produced highly ozonated water that was injected into the blades of the CLEANHATCH arms. This system could reach ORP values of 800mV. To prevent the accumulation of Total Residual Oxides (TROs) an activated carbon filter was fitted to the inflow pipe of the sedimentation tank of the experimental system since activated carbon can absorb TROs.
Task 3.2: On-site pilot scale testing and optimisation of CLEANHATCH system
The on-site testing took place at the state-of-the-art facilities of ABT in Malta. The facilities include 5 self-contained and biosecure recirculation systems and a live-feed testing facility. Each tank system is completely independent and could therefore have a completely different set of rearing conditions. During the on-site tests, all partners were involved continuously. During the testing phase, partners operated and continuously evaluated the application of the new cleaning technology in the larval hatchery in order to prove the advantage of the technology.
In all, five larval trials were carried out, two with seabass, two with seabream and one with trout. In addition, LC50 ozone trials were conducted on rotifers. LC50 is a standard measure of the toxicity of the surrounding medium that will kill half of the sample population of a specific test-animal in a specified period through exposure. Furthermore, disinfection trials using ozone were conducted to better understand ways of measuring ozone and which ozone concentrations are best to use in the CLEANHATCH system. All experimental and control groups were run in triplicate and the respective statistics (ANOVA and t-test) were carried out using SPSS 13.0 for Windows. Whilst further testing is still required to achieve a fully marketable product, some very positive outcomes have been achieved as a result of WP3.
It was shown that CLEANHATCH:
- has reduced cleaning-related labour costs by 80%;
- has resulted in a 32% increase in the final weight of trout larvae';
- significantly reduced bacterial counts on tank surfaces;
- is safe and easy to operate;
- enables the use of a small metal mesh that does not require cleaning and regular replacement;
- has no negative environmental impacts;
- operates in TRO values that are below the safety thresholds; and
- is economically viable with potentially significant reductions in production costs;
During the FIRST LARVAL TRIAL, seabass larvae were used. Results from this trial included:
- No significant differences in bacterial counts, larval survival, FCR, deformities or water quality between experimental and control groups.
- The final length, weight and SGR of larvae were significantly better in the control system.
- Time required for manual cleaning of the tanks was reduced by 80%.
- Several modifications necessary to improve CLEANHATCH were highlighted.
Results of the SECOND LARVAL TRIAL (also on seabass larvae) included:
- No significant differences for larval length, weight, survival and condition factor between experimental and control groups.
- No significant differences for bacterial counts on the tank walls between experimental and control groups.
- Bacteria identified were Psuedomonas aeruginosa, Pseudomonas luteola and Pseudomonas fluoresce/putida.
- Various halogenated compounds (trihalomethanes, trihalogenacetonitriles, and haloacetates) were identified and found to be below the safe levels of 0.06 mg/l.
Results of the THIRD LARVAL TRIAL on rainbow trout in terms of larval growth were beyond the expectations of the consortium:
- Trout in the experimental system showed 32% higher weight and 6% greater length.
- FCR and survival showed no significant differences between experimental and control groups.
- No significant differences for bacterial counts on the tank walls between experimental and control groups.
Following this trial and the inability to achieve any level of measurable disinfection, several experiments using ozone were conducted to better study its disinfection capabilities, instead of relying entirely on literature.
a) Mini-trial 1 - Ozone chemistry and measurement methods
b) Mini-trial 2 ORP levels necessary to disinfect bacteria of tank surfaces
c) Mini-Trial 3 The effect of high ORP levels in the CLEANHATCH arm
Following the necessary modifications in the CLEANHATCH arm, LARVAL TRIAL FOUR using gilthead seabream was started. The results obtained were not as good as expected for the fish, but better results were obtained for disinfection:
- Final larval weight, length, survival and SGR were significantly lower in the experimental system when compared to the control system.
- When low ORPs were used (250 mV), the control tanks had lower bacterial counts indicating that the arm spreads bacteria around the tank and does not have any disinfection abilities at low ORP.
- The increased ozone level showed better disinfecting effects for the experimental system at 450 mV, 700 mV and 800 mV after using the arm compared to the control system, however results were not always significant.
Results from LARVAL trial five included:
- No significant differences in larval final length, weight, condition factor, SGR and survival during the second phase of the trial between experimental and control groups.
- Significantly lower survival in the first period of the trial (particularly in the first four days of the trial when the arm was still not switched on) indicating that the presence of the arm (or some other unknown factor) has negative effects on the larvae.
- The movement of the arm around the tank spreads bacteria around the tank surfaces to such a degree that it cancelled out the effect of the ozone completely. However if the arm rotates (using ozone) more than once a day, this issue may be overcome.
- TROs were kept below the safety threshold even at high ozone concentrations due to the use of an activated carbon filter, together with the biofilter.
Live-feed trials
Trials using batch cultured rotifers (LC50) were carried out continuously throughout WP3. Upscaling was also attempted several times, which were unfortunately unsuccessful due to culture crashes for various reasons, some of which remain unknown. Because of this, live-feed trials using the CLEANHATCH technology could not be conducted, but still several interesting results were obtained from the LC50 trials and batch culturing.
Results from this trial included:
a) Batch culture production:
- The highest rotifer production was observed at the higher temperature ranges (within the optimal) at between 27°C and 28°C with an average of up to 1,400 rotifers/ml.
- Above 28°C, (29°C and 30°C) the reproduction dynamics of the culture reduced and the water quality was also negatively affected.
- Good rotifer production (800 rotifers/ml) was observed between 24°C and 26°C but the average density was less than at higher temperatures.
- Below 24°C the average rotifer density in the batch culture was around 400 rotifers/ml and less stable.
- The highest egg production and greatest increase in rotifer density were observed between day 2 and 3. On the fourth day the population was still increasing, but this population growth was reduced in comparison with the preceding days.
b) LC50 trial:
- The average ORP value should be less than 240 mV in the rotifer culture tank.
- If high egg production is not realised at high rotifer density, or the egg production drops below 25%, the ozone value should be decreased.
- It is recommended that the amount of TROs is measured should the CLEANHATCH technology be used for rotifer production.
Task 3.3 Design of CLEANHATCH system for production scale
After the pilot scale tests a number of changes were necessary to optimise the CLEANHATCH system. During the test several factors were monitored to improve the functionality and handling of the system. In order to develop a production scale system new components were developed and some existing parts were changed. With the redesigned arm and other changes in the system most of the problems that occurred in the pilot test were solved and a more market ready system was developed. To check functionality of the improved design and to gain experience in different working conditions, production scale tests at VIKING in Scotland were planned. In task 3.3 the production scale prototype was constructed and installed ready for testing. The development of the production scale system included new CFX simulations to support the design work. The simulations were mainly focused on the calculation of the stability of the new frame. The steel frame from the first prototype was exchanged for an aluminium frame to avoid corrosion. The stability of the new frame was simulated for several tank dimensions, to ensure that the system could be applied in many different facilities. The results of the simulation showed that the stability for tanks up to a diameter of 4 m was good.
The main advantages of the redesigned system were:
- The arm was made mainly of standard readily available parts.
- The need for specially manufactured parts was reduced.
- Usage of corrosion resistant parts.
- Easy installation.
- Easy adjustment.
Task 3.4: Production Scale Testing
At VIKING's facilities, the final tests on another marine species, turbot, were undertaken in more production orientated conditions with the new CLEANHATCH prototype. Essentially, the production scale tests aimed to prove the production scale CLEANHATCH technology and ensure that the operating protocols, developed in task 3.3 were valid and applicable. It also aimed to determine whether changes needed to be made. Whilst it was planned that this task takes place after all task 3.2 was complete, it was in fact run in parallel with larval trial four in ABT. This is because turbot larvae are only available between July and August, and because task 3.2 actually finished in December (month 28). It would have therefore not been possible to run a turbot trial at that time. The trial was mainly run by VIKING with constant support from both the RTDs and SMEs.
Based on the application of the CLEANHATCH arms at the Viking Fishfarm (Ardtoe, Scotland), it can be stated that the present design of the technology is not yet a marketable product. Although the ozonated water decreased the amount of bacteria, the survival rate of larvae was not acceptable for turbot. Further improvements are needed to increase the effectiveness of the system.
The observed problems during the trials included:
- Due to the irregular walls of the tanks, the frame could not successfully maintain contact with the tank walls, resulting in ozonated water entering the fish rearing system and/or the larvae entering the ozonated area.
- During the rotation, the frame sometimes stops and 'jumps', so the ozonated water can again mix with the tank water.
- Not enough accuracy in the regulation of the ozone injection system.
The following solutions and improvements would be desirable in order to make CLEANHATCH a marketable product:
- Applying more flexible and softer blades.
- The canal which contains the ozonated water should be held against the bottom of the tank with a spring mechanism to maintain contact.
- More dynamic connection between the motor and the frame to avoid the 'jumps'.
- Applying a collection tube to the bottom of the frame outside the blades which can help to channel the ozonated water into the standpipe
Task 3.5: Overall evaluation of system performance
Based on the experiences and data gathered during the previous tasks, an overall assessment of the system performance under real testing conditions concerning all the relevant indicators developed in Task 1.1 was prepared. Keeping in mind the potential markets in the hatchery sector, results were evaluated regarding suitability of the new CLEANHATCH technology and its advantages for disinfecting and improving the overall water quality. The respective deliverable 3.9 was prepared.
Main outcomes:
1) Bacterial counts decreased at 800 mV with a rotation speed of one rotation per 3 hours; however they quickly increased again and so the arm needs to be used more than once a day.
2) The arm had no effect on general water quality parameters and TRO values remained below the safe threshold.
3) Excellent results were obtained in the trial using trout where final weight and length were 32% and 5.6% respectively higher than those seen in the control system. Additional testing is still needed to resolve whether or not the results obtained are completely due to CLEANHATCH or if other unknown factors are at play. Unfortunately, less positive results were obtained for marine larvae and therefore additional testing is required.
4) RAS reduces water exchange to only 10% over flow through or partial reuse systems. CLEANHATCH reduced this by a further 66% to require a water exchange of only 3.4% per day.
5) Energy consumption was low and so is a minor cost.
6) CLEANHATCH can result in significant potential production cost savings, particularly if used in Nordic countries where labour costs are high.
7) Materials used in CLEANHATCH are resistant to the corrosive conditions of ozonated and saline water at warm temperatures.
8) The CLEANHATCH arm can be used extremely easily after installation as it an automated system requiring minimal maintenance.
Work still to be done to reach a fully commercial stage:
1) Additional testing on marine species to determine at which stage CLEANHATCH is most suitable for use.
2) Additional testing on salmonid species to give additional value to the results already attained.
3) Testing on live feed production systems.
4) Additional testing to achieve higher disinfection.
5) Further automation for ozone control.
Potential Impact:
The impact of CLEANHATCH on the European market and its SMEs has the potential to be significant. For the reasons explained above, the industry is in need of an automated, cost-effective and reliable technology for the cleaning and disinfection of larval tanks. Thus, the commercial potential of the developed CLEANHATCH system is high, especially as the product will be able to be 'retro-fitted' to many existing systems as well as designed into new bespoke operations. Accordingly, it is expected that the new CLEANHATCH system will find significant application in European hatcheries (potential customers for ABT and STORVIK). It will allow the European hatchery industry to improve their production processes by improving the current cleaning and disinfection operations, which will ultimately lead to a drastic reduction in maintenance costs (it is estimated that hatchery operators dedicate around 40-50% of their production time to cleaning operations), reduced biosecurity risks, significant increase of productivity through higher survival rates, higher reliability of the overall system, and thus higher revenues.
ABT, having already achieved a significant share of the global RAS market, will continue to increase its market penetration in southern Europe by offering a completely new technology which has been required by the industry for years. The expected resulting new orders will be numerous. A single contract to design and supervise a hatchery construction can be worth more than EUR 250,000 with some contracts now exceeding EUR 1 million. Therefore, by acquiring a whole new range of clients through offering this new system, there will not only be the direct benefits of selling the specialist technologies (the CLEANHATCH system for larval hatchery and live feed culture) but also indirect benefits encompassing all other services included in such a contract. Clients increasingly expect full turn-key packages to conveniently cover all their requirements and so increasing the remit of services will ultimately increase competitiveness. Such a development could make ABT a market leader in designing and overseeing hatchery constructions, focussing on clients in the Mediterranean, but also in the Middle East. As a result, in relation to the amount of money that is being invested in CLEANHATCH, the company's increased sales will give a direct return over a period of approximately 6 years. By the close of the CLEANHATCH project, ABT had already won a project to develop a trout hatchery and will test the arm further in these new facilities. The results obtained in the trout trial were of key importance to this project.
In extending their product range, STORVIK, as leading technology provider for aquaculture facilities in Northern Europe, will similarly gain an enormous competitive advantage. This will establish their reputation as a global company at the forefront of aquaculture technologies. STORVIK will market the new cleaning technology with a focus on the Scandinavian countries and the UK, also including freshwater hatcheries in their portfolio. By providing their customers with the most advanced technology in the market, they will not only have a stronger presence in the Northern European market, but also the global market (in particular Canada and Chile) in the fast growing hatchery RAS market, allowing them to remain a worldwide acknowledged company at the forefront of aquaculture technology supplies. The new cleaning technology, sold as a single module, will be worth up to EUR 3,000 per system and tank, multiplying to EUR 96,000 for a typical small- to mid-sized hatchery consisting of 32 tanks.
VIKING, in providing fry of highest quality to its clients (from species such as cod, turbot or haddock), will be the first commercial hatchery profiting from the results of the CLEANHATCH project. With additional testing, VIKING will benefit from lower production costs, higher survival rates of species cultured and thus higher overall profit, enabling them to outcompete their competitors. VIKING will also profit from the new knowledge accumulated during the project, especially through the production-scale tests carried out at VIKING's facilities.
After the project termination and in accordance with the Research for SMEs scheme, the participating SMEs are now the owners of the CLEANHATCH system (both as an integrated part in new larval hatcheries and also in its specific modular parts), which was developed, tested and optimised during this project. In addition, they own the required knowledge about possible malfunctions or optimisation/decision-tree paths regarding the new technology, as well as relevant factors for the overall evaluation of the system performance.
With the on-site testing phase (WP3), the project was designed in such a way that no further technical development or demonstration activities would be required after the completion of the project to prove the efficiency and optimal performance of the CLEANHATCH system and to produce a marketable system and modules. Unfortunately, a fully marketable product was not achieved, however with some more development, this target is very realistic. The SMEs, led by ABT, can take over this final work in-house at their own R&D facilities, as the major tasks needed to be undertaken by the RTDs were almost finalised within the framework of CLEANHATCH.
CLEANHATCH will contribute to the community societal objectives by improving quality of life, health, safety and the environment. Fish farmers who upgrade their production systems will have an advantage in producing high quality, safe and healthy aquaculture products to meet the increasing health and quality requirements of consumers and European legislations. By helping complying with the EU water framework directives by improved water quality management through the CLEANHATCH system, facilities will optimise their fish production in a sustainable, safe and healthy way. The wide ranging impacts of developing this technology will help to drive the overall goals of environmental protection, water sustainability, food security and animal welfare.
Aquaculture is noted as an opportunity for economic development and re-employment particularly in the small, family managed sector. With its potential for full-time employment, it has an important role in the general stabilisation of rural areas where job opportunities are becoming increasingly limited. CLEANHATCH also addresses the objectives pointed out in the EC 6. Environment Action Programme, especially in the field of nature and biodiversity protecting a unique resource. It contributes towards minimising waste production and water pollution by chemicals by improving sterilisation of farms and adding security for local biodiversity exposed to effluents.
Moreover, different European and national legislations are addressed in the field of water and health via this project, such as the directive on economic development and re-employment (COM 2002/511), water framework directive (2000/60/EC), Groundwater Directive (80/86/EEC), policy for the regulation and control of fish diseases (Directive 91/67/EEC), animal health condition (Directive 93/53/EEC) or the wastewater treatment directive (Directive 91/271/EEC).
Dissemination Activities
Various dissemination activities were undertaken with regards to CLEANHATCH. These included:
1) A website, the development of which STORVIK was responsible for. Since the consortium does not have professional staff for web design, the task was subcontracted and launched in month 3. Amongst others, the website has the following features:
a. A distinctive domain name, http://www.cleanhatch.net/
b. Project summary, description of objectives and expected results.
c. Description of partners, contact details and links to their web pages.
d. Links to conferences and exhibitions consortium members attended.
2) A poster and flyer were created by ABT, together with STORVIK and VIKING. The material was produced in English.
3) A power point presentation was also created by ABT, STORVIK and VIKING. Similarly, the material was produced in English.
4) A list of conferences, trade and industrial fairs was drawn up. This list is continuously updated as new events are announced.
a. ABT attended European Aquaculture '10 in Portugal and Future Fish Eurasia 2010.
b. ABT, STORVIK and VIKING attended the Aqua Nor 2011 Exhibition in Norway. Here the poster was presented and flyers distributed.
c. STORVIK attended DanFish International in October 2011 and Aquaculture UK in 2012.
d. ABT and STORVIK attended Aquaculture Europe in October 2011 in Greece. A joint stand was put on display.
e. Personnel from ABT attended Aquaculture America 2012 in March 2012, and AGREme in April 2012.
f. ABT presented CLEANHATCH to the Maltese President, Dr. George Abela, and the scientific community during a presidential visit to the Malta Council of Science and Technology (MCST) on 08 March 2012.
g. All the consortium members attended Aqua2012 in Prague. The consortium meeting of September 2012 was purposely set in Prague so as to facilitate the attendance to this important exhibition. There, Dr. Jack M. James from ABT gave a presentation about the results attained.
Scientific publications have not yet been prepared as the consortium would like to conduct some additional testing prior to doing so, and also due to intellectual property rights reasons.
Project website: http://www.cleanhatch.net
Maria-Liza Scicluna
Projects Manager
AquaBioTech Group
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