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Development of an automatic process of in-house collection, storage and application of adaptive bacteria culture for fish farms

Final Report Summary - ADAPOND (Development of an automatic process of in-house collection, storage and application of adaptive bacteria culture for fish farms.)

Executive Summary:

The Adapond project was brought to life with an aim to increase the reliability of nitrifying biofilters used in recirculation fish farms. This was planned to be achieved by reducing the biofilter recovery time after failure through developing an Intelligent Biofilter Control (IBC) system with three critical components:
* Real-time monitoring system will enable detection of the viability and metabolic activity of the bacteria culture.
* At healthy period excess bacteria are extracted, prepared for storage and stored by automatic collection system.
* In case of biofilter failure, the stored culture will be cultivated for rapid recovery of the biofilter thereby providing increased productivity of the farm.
As a result of the project, a device and protocol for on site storage and recultivation of nitrifying biomass was developed. More detailed concept and advantages of this technology are described below.
Project Context and Objectives:
Considering the steady increase of human population, the public demand for aquatic food products is growing. However, production from capture fisheries has levelled off and most of the main fishing areas have reached their maximum potential. Therefore it is not surprising that the aquaculture - seafood farming - is the fastest growing food production system in the world.
As the amount of farmed seafood produced rises, it is critical to minimize the negative impacts of aquaculture to the environment. The concept of recirculation aquaculture systems (RAS) is designed to meet that objective. In RAS, fish are reared at high densities, in a controlled environment. The heart of the RAS is the biofilter that is responsible for removing any harmful waste so that up to 97% of the water can be recirculated.
Biofilter is composed of a media (corrugated plastic sheets or beads or sand grains) upon which a film of beneficial bacteria grows. The bacteria provide the waste treatment by removing pollutants. Being an alive entity, biofilter is sensitive to environmental changes. Antibiotic treatment of fish, cold winter or a number of other unfavourable situations may drastically reduce the number of biofilter bacteria and hence it's water treating capability. It takes weeks to months to establish or recolonize a biofilter, meaning a low production for the farm. During the period of decreased functionality of the biofilter fish may become intoxicated and the whole stock may be lost, which is a serious issue for beginning recirculation farmers. Taking all this into consideration it is not surprising that new starters experience 30-80 % of loss in sales almost unavoidably through the first year during the adaptation period of the biofilter, accompanied by the failure losses from fish medication and seasonal depressions counting summingly for more than € 70-90 M annually in Europe.
To overcome this, the Adapond consortium aimed to reduce the bio-filter recovery time after failure by developing an Intelligent Biofilter Control (IBC) system with three critical components:
* Real-time monitoring system will enable detection of the viability and metabolic activity of the bacteria culture.
* At healthy period excess bacteria are extracted, prepared for storage and stored by automatic collection system.
* In case of biofilter failure, the stored culture will be cultivated for rapid recovery of the biofilter thereby providing increased productivity of the farm.

Project Results:
The RTD activities in the first project period were dedicated to the achievement of the scientific objectives. As a result novel strategies for monitoring, storage and recultivation of nitrifying biofilm were formulated. During the second period the consortium focussed on testing and validating of developed strategies. To enable a fish farmer to create a back-up of his adapted biofilter, a storage protocol was developed which enables the maintenance of 50% of initial ammonia removing activity over the storage period of 4 months. Secondly a recultivation (boosting) protocol was developed, enabling further increase in nitrification activity after storage. To demonstrate the feasibility of these concepts, a large scale prototype of Adapond system was built and installed in a commercial farm. The results of the prototype testing confirmed the functionality of Adapond concept.
The consortium somewhat struggled to achieve the monitoring of the viability and metabolic activity of nitrifying biofilter microbes. Initially it was planned to be accomplished by means of online monitoring of water chemistry parameters but unfortunately it was found that current state of the art of online monitoring sensors does not allow this to be accomplished. Unfortunately improving the sensors was not in the scope of Adapond project.
To recover from that, a software was developed, allowing the calculation of nitrification speed, using the measurements of ammonium monitoring sensor as an input.
Adapond system can be used in several modes. In back-up mode the prototype can be used to keep nitrifying biofilter organisms attached to biofilm carriers at a low temperature in a dormant state so that they are ready to be used as a seeding material for a new biofilter in case of a failure of the working biofilter.
During boosting mode synthetic wastewater is provided to the nitrifying biofilter organisms and temperature, pH and oxygen content are maintained in a controlled range, favourable to the growth of nitrifying bacteria. This mode serves to accelerate the growth of nitrifying bacteria biomass, thereby enabling further increase in the ammonia and nitrite removal capacity of the nitrifying biofilter. On the one hand using the Adapond prototype in this mode provides additional nitrogen removal capacity in times of increased loading of the working biofilter. On the other hand boosting of the stored biofilter material helps to increase its efficiency as a seed to a new biofilter in case of a working biofilter failure.
In monitoring mode nitrification rate of a biofilm sample can be found. This gives information about the viability and metabolic activity of biofilter nitrifying organisms. Sudden changes in that parameter suggest problems with biofilter functionality and are a sign of possible future failure of the biofilter to cope with the loading levels in the fish farm.

Potential Impact:
Using Adapond technology offers several advantages. Here the nitrifying biofilter microorganisms are stored while being attached to the biofilter carrier material. It is important to the rapid initiation of ammonia removal that the nitrifying biofilter microorganisms exist in biofilms as the microbes in such a state are instantly capable of starting to remove the harmful nitrogen compounds from the RAS environment. Enrichment cultures of nitrifying bacteria commercially available on the market are all in liquid, dried or freeze dried form and therefore easily washed out from the system. It will require a substantial number of weeks until such microbes attach to biofilm carriers and form biofilms prior starting to contribute to the removal of ammonia. Nitrifying biofilter microorganisms in Adapond biofilter back-up and boosting system are already attached to the biofilter carrier material and therefore remain in the system.
Secondly Adapond technology enables the farmer to store nitrifying consortium that is specifically adapted to the wastewater parameters of this specific farm. Research has shown that the reaction rate in a biofilter is influenced by the history of the biofilter microorganisms. As a result biofilter seeding material must include microbes that are tolerant to the conditions in which they are expected to perform. Therefore the application of biofilter back-up and boosting system is advantageous over importing nitrifying biofilter material from another site. Secondly this eliminates the risk of transferring diseases between farms.

List of Websites:

More information about Adapond project can be found on the project website at http://adapond.eii.ee and from project coordinator Remedium AS at e-mail address info@remedium.ee