Skip to main content

Development of a Cost Effective, Low-Maintenance, On-Line Instrument to Detect Heavy Metal Concentrations in Wastewaters

Final Report Summary - METELCAD (Development of a cost-effective, low-maintenance, online instrument to detect heavy metal concentrations in wastewaters)

Executive summary:

Industrial wastewater, contaminated by heavy metals, migrates to surface and underground water sources. Heavy metals are elements that have a high density and are toxic or poisonous even at low concentrations. The METELCAD project aimed to develop an online, low-maintenance, on-site, continuous monitoring device for the detection of heavy metals in wastewater.

After formulating the market needs by a questionnaire survey, the individual parts of the METELCAD device were developed. The main features of the METELCAD measurement device are a flow through measuring cell for 10 ml per minute liquid flow rate, measure range for Cd concentration in the range of 0.1 - 10 mg / l and for Zn, Cu, Ni and Pb levels in the range of 1 - 100 mg / l; the frequency is automatically adapted to the pollution event detection: the higher the observed concentration the higher the sampling frequency ranging from 2 to 6 sampling / hour.

The different parts of the METELCAD device were developed individually in the first step: (i) A sample treatment unit tailored for the special composition (emulsions) of wastewaters was developed, containing a sucking-filtering rotation unit, was developed in the framework of this project. Further, the preparation of an analytical sample and automatic adjustment of the pH was carried out. (ii) An electrode discharge cell was developed. It is a flow though cell, in which cold plasma is generated and acts as emitter of light with specific wavelength determined by heavy metal contamination. The optimal geometry and also high-voltage power supply was developed within the project framework. (iii) A spectrometer and its optical connection system was defined and constructed according to a design optimised carefully.

Using the results of parts developed in the previous tasks, the experimental METELCAD device was constructed. The electric and hydraulic connections were designed to be compact and handy, and to ensure smooth working conditions. Parallel with physical integration, a control panel, software and hardware specifications for operation and PC communication was developed. The control of the METELCAD system is divided in two parts: the microcontroller with embedded software, that is built in the METELCAD measurement unit and a PC-based software, which also acts as an interface for user communication. The microcontrollers control the individual units of the system.

The METELCAD system was tested in three different fields: at Bohumin Steal Works in 13 - 16 July 2010 at the Czech Republic, Permastore in the United Kingdom (UK) between 13 and 16 December 2010, and in Malta by WSC between 15 and 18 January 2011 organised by WSC. During these trials the METELCAD monitor was working autonomously for more than 72 hours. The results of the METELCAD monitoring were in accordance with parallel conventional laboratory tests. Calibration was good. Spiking with internal standard solution was successful, resolution and detection limit of the METELCAD monitor was acceptable. A continuous development was carried out in the control software and plasma lighting system from test to test. These modifications were done during the accepted 3 month amendment period of the project. Most importantly, a new charge-coupled device (CCD) spectrometer unit was successfully integrated to the METELCAD system and new software was developed using LABVIEW software. The project archived all technical objectives that were set up in the proposal.

Besides the technical developments, dissemination and exploitation actions have taken place. The partners agreed on a joint ownership agreement (JOA) with consideration to the individual interests of each small and medium-sized enterprise (SME) partner in the consortium. The exploitation strategy and a preliminary business case were also agreed between the partners.

Project context and objectives:

All contaminated water, whether originating in industry, agriculture or households, causes damage to the environment and to human health. Industrial wastewater, contaminated by heavy metals, migrates to surface and underground water sources. Heavy metals are elements that have a high density and are toxic or poisonous even at low concentrations. In addition to wastewater, sewer sludge, the residual semi-solid material remaining from urban and industrial wastewater treatment processes, also contains high levels of heavy metals. The consortium members of the METELCAD project recognised that with the advent of increasing environmental European Commission (EC) directives, there is a critical need in Europe to develop a low-cost, and efficient detection technology for metal contaminated wastewater to safeguard public health and reduce pollution and clean-up costs. The METELCAD device aimed to detect heavy metal presence in wastewater before it is released into the environment or before it reaches the sludge stage. The commercial objective of the project is to develop an online, low-maintenance, on-site, continuous monitoring technology utilising electrolyte cathode glow discharge technique to monitor heavy metal contaminated wastewaters that are loaded with high fat emulsion. This cost-effective technology would facilitate compliance with the European Union (EU) environmental legislation in a business-friendly manner, facilitating industrial wastewater management. The developed technology is also relevant to other industrial sectors including ferrous and non-ferrous metals industry.

The project objectives can be summarised as follows:

(a) to evaluate EU needs and environmental concerns on heavy metals;
(b) to develop flow through cell that yields 10 ml per minute;
(c) to measure Cd levels (range of 0.1 - 10 mg / dm3);
(d) to measure Cu, Ni and Pb levels (range of 1 - 100 mg / dm3);
(e) to perform 2 - 6 measurements / hour, depending on the observed value;
(f) to measure ranges to cover the values from the permitted discharge concentration to 10 - 20x of that value;
(g) to measure frequency to be changeable on an adaptive mode, the higher the observed concentration the higher the sampling frequency (from 2 to 6 times / hour);
(h) to develop instrument to be equipped with data transmission to a data acquisition centre where the necessary actions will be launched in case of critical situation expected;
(i) to carry out exhaustive tests on the constructed prototype and to make sure that all the requirements from previous tasks have been met (laboratory tests and industrial / field tests);
(j) to support the participating SMEs in protecting and using the research results to their best advantage and exploitation of the result-training, report on intellectual and property right (IPR) protection, knowledge management.

Project results:

The problem

All contaminated water, whether originating in industry, agriculture or households, causes damage to the environment and to human health. Western Europe is one of the most highly industrialised regions of the world and in north-western Europe alone industry is the largest water consumer, with a share of around 45 %. Significant water and soil pollution by nitrates, pesticides, hydrocarbons and heavy metals has been reported from many EU countries (Water Technologies Press Release. Siemens: Water as a raw material is a location factor in Europe: Water reclamation and water cycle management strengthen competitive edge. 3rd Press Conference Infrastructure Water Technology Europe, Berlin 9 May 2006) (Freshwater. GEO-2000. Global Environment Outlook. United Nations environment programme).

Heavy metals are elements that have a high density and are toxic or poisonous even at low concentrations (Heavy metal pollution and human biotoxic effects by Duruibe, J. O., et.al. International Journal of Physical Sciences Vol. 2 (5), pp. 112-118, May 2007). Industrial wastewater is a recognisable source of European pollution and untreated wastewater containing chemicals and elements such as heavy metals are extremely dangerous, as these toxic substances accumulate in living organisms and contaminate aquatic ecosystems. The heavy metals commonly implicated in pollution and human poisoning includes lead, mercury, arsenic and cadmium. Industrial sources of heavy metal pollution in water include the mining and processing of metal ores and the finishing and plating of metals. Metallic compounds widely used in other industries include pigments in paints and dye manufacturing and the manufacturing of leather, amongst others.

The contamination through the feeding cycle involves pollution of agricultural soils with heavy metals absorbed by plants and animals which are in turn consumed by humans. Heavy metals are dangerous because they bio-accumulate, that is, they increase their concentrations in biological organisms over time and are stored in living organisms faster than they are broken down (metabolised) or excreted. Epidemiological studies on the effects of lead on human health suggest that exposure to heavy metals can be carcinogenic. Low level exposure to lead, for example, by the foetus or developing child may lead to reprotoxic (substances that interfere with the reproductive process) effects which include damage to the learning capacity and to neuropsychological development. Lead has also been shown to have effects on haemoglobin synthesis and anaemia has been observed in children with lead blood levels above 40 µg / dl (Heavy Metals in Waste. Final Report. EC DG ENV. E3 Project ENV.E.3/ETU/2000/0058. February 2002).

In addition to wastewater, sewer sludge, the residual semi-solid material remaining from urban and industrial wastewater treatment processes, also contains high levels of heavy metals. The amount of sewage sludge has been increasing enormously. In 1992, 5.5 million tons of dry matter was the annual EU production while in 2005 it was approximately 9 million tons. Control of such polluting substances at the stage of industrial wastewater is vital since sewer sludge is used in agriculture, as it also contains valuable agronomic (Application to various soil and plant sciences to soil management and crop production) properties. The EU has instituted significant regulations for treatment of sludge including the Sewage Sludge Directive 86/278/EC which requires very close monitoring of the concentration of heavy metals in sludge. Since December 2000, EU Member States have been obliged to implement one of Europe's most complex and demanding laws - the EU Water Framework Directive (WFD) that effectively reorganises, under the same legal system, over 30 regulations and previous legal instruments regarding water, thereby forming the basis for EU water policy in the use and the management of water resources (Europe's water law: stronghold against commercialisation. European Public Health Alliance. Update 67 (2003)) (WISE Newsletter. The Bulletin of the Water Information System for Europe, Issue No. 5, June 2007).

The heavy metal pollutions reaching the sewer systems are, fortunately, accumulating in the sewer sludge remaining from urban and industrial wastewater treatment processes. Control of such polluting substances at the stage of industrial wastewater is vital since unpolluted urban sewer sludge can be used in agriculture. On the other side a havaria situation can happen when a pollution peak in the incoming wastewater stream kills the biological life in the treatment process to such extent that untreated water goes into the receiver water body for a 1-to-3-day period.

Analysis data of the sludge of municipal waste water treatment plants clearly indicate the presence or absence of industrial metal releases in a collecting area. At many areas having plating shops, pharmaceutical factories, tanneries and other chemical activities, Zn, Cd, Cu, Cr, Pb, Ni, etc. concentrations can be measured sometimes well above the relevant sludge background values, while the standard daily analysis data show that inflow waste water concentrations are always below the limits. The present checking practice of sampling the sewerage system at every weekday morning is absolutely useless for discovering the sporadic pollution events which most probably happen 0.5 - 2 hours long during night times, weekends or holidays, but only 10 - 20 times in a year.

The METELCAD project recognises that with the advent of increasing environmental EC directives, there is a critical need in Europe to develop an efficient detection technology for metal contaminated wastewater to safeguard health and reduce pollution and clean-up costs. METELCAD will allow hazardous material control services to detect heavy metal presence in industrial wastewater before it is released into the environment or before it reaches the sludge stage.

The innovative technology of METELCAD, based on a new analytical measuring principle (electrolyte cathode glow discharge spectrometry), makes the detection of heavy metals presence possible directly in raw wastewater sample. This new method can run with samples that are loaded with fat, oil and grease emulsion and high suspended matter at an extent of 100 - 1 000 mg / L. The method detects all free and complexed metal ion forms existing at pH 1.6 - 1.7 in the sample water.

METELCAD is the first wastewater monitoring technology that can detect heavy metal pollutions in fat-emulsion loaded wastewater streams entering the treatment technology.

The METELCAD measuring process runs with ambient air, no mineralisation or other special reagents used, only acidification by HCl to pH 1.6 - 1.7 requires 5 - 10 mL / min sample flow by the monitor during measurement.

The main features of METELCAD include:

(a) to develop flow through measuring cell for 10 ml per minute;
(b) to measure Cd levels (range of 0.1 - 10 mg / dm3);
(c) to measure Zn, Cu, Ni and Pb levels (range of 1 - 100 mg / dm3);
(d) the measurement ranges to cover the values from the permitted discharge concentration to 10 - 20x of that value;
(e) the measurement frequency is automatically adapted to the pollution event detection: the higher the observed concentration the higher the sampling frequency ranging from 2 to 6 sampling / hour.

METELCAD is highly relevant to decreases the risk of contamination from wastewater to sludge as wastewater management companies focus much of their business on sludge recycling. Costs for regulatory compliance for industrial sludge EU-wide ranges from 0.1 billion EUR / year to 0.2 billion euros per year with costs borne mostly by industry at 60 %, followed by local authorities at 20 % and water companies at 8 %, with the remaining costs borne by citizens, including farmers (Disposal and Recycling Routes for Sewage Sludge Synthesis Report (2002). EC). Reduction of such costs could be facilitated by the proper detection of contamination at the industrial source, reducing the possibilities of heavy metals entering the sewage system and reducing the cost of sludge treatment as well as ensuring sludge quality. Recognising the presence of heavy metals in the incoming water streams with METELCAD, different treatment methods can be applied to discard of dangerous materials in an environmentally friendly manner while sludge quality remains at a high level.

METELCAD will be particularly useful to SME industries since many commonly lack the necessary knowledge and experience greater challenges in complying with wastewater control legislation, as compared to large enterprises. In a 2005 survey conducted by a UK Environmental Agency, of the 5 000 British SMEs surveyed, only 6 % had an environmental management system in place ('The clean business programme', Partnership for the Environment Foundation, October 2005). The study suggested also that SMEs require greater access to professional advice on how to comply with requirements from environmental experts specialised in SMEs. The problem is compounded by the fact that there are not sufficient experts to meet the need of the SME market and that these services can be expensive (A Comparative Analysis of the Environmental Management, Performance and Innovation of SMEs and Larger Firms For the EC, Directorate-General for Environment. Final Report, 31 August 2006 by CL Conseil, France). SMEs have limited financial resources for in house monitoring systems and equipment. The difficulties experienced by SMEs with increasingly complex and technical legislation are such that the EC has proposed an environmental compliance assistance programme (CAP) to make it easier for SMEs to comply and improve their water-related environmental performances. Industrial wastewater management has rapidly become one of the fastest growing challenges to industry, demanding new technologies that can address particularly difficult pollutants such as heavy metals (A Comparative Analysis of the Environmental Management, Performance and Innovation of SMEs and Larger Firms For the EC, Directorate-General for Environment. Final Report, 31 August 2006 by CL Conseil, France).

The core development

The most widespread method for determination of metal concentrations in wastewater is via grab sampling and subsequent laboratory analysis. This method is both costly, which limits its frequent application, and slow as typically involves a 24-hour turnaround time, which means that pollution events can be missed, or detected too late. In the face of increasing levels of sludge production, the expected application of more stringent limits on heavy metal concentrations in sludge, and the need to identify, survey and control the sources of input of toxic elements, there is a need for an online instrument to detect heavy metal pollution events in wastewater in real-time: both at the inlet flow to wastewater treatment plants, and at the source of potential discharges.

Laboratory multi-metal analytical methods based on a 24-to-48-hour automatic sampler are not applicable at the necessary 1 500 sample / month throughput (min 50 samples / day). The problem can only be solved by a proper analytical monitoring technique with analysis at every 30 minutes. However, no such metal monitor is available for the analysis of mixed domestic and industrial wastewaters. Due to the high load of fat, oil and grease (FOG) emulsion and suspended solids, in the range of 100 - 1 000 mg / L, these waters cannot be analysed directly by the well-known and high performance laboratory methods (ICP, electrochemical methods). It must be emphasised that at the usual 7 - 8 pH value of domestic wastewaters, heavy metals are mostly in the suspended solid fraction as hydroxides, sulphides and carbonates, or partly complexed and bonded to the suspended organic particles. Since the well-known and widely used water quality monitoring methods like electrochemical sensors and colorimetric cells can accept only FOG-free samples with ionic metal forms, sophisticated and expensive sample treatment (including mineralisation) procedures are required to achieve reliable operation over 1-5 consecutive measurements.

The historical starting point in the field of electroanalytic methods is polarography (Heyrovsky 1953, Nobel-prize), with the subsequent arrival of derived solid-electrode methods (voltammetry). In favourable cases the selectivity of these methods may make it possible to detect 4-5 metal components simultaneously present in the sample. With the anodic stripping method (S. Daniele, I. Ciani, C. Bragato and M.A. Baldo, 'Detection of heavy metals released at the sediment / water interface by combining Anodic Stripping Voltammetry (ASV) and Scanning Electrochemical Microscopy (SECM) measurements' J. Phys. IV France 107 (2003) 353), an electrochemical pre-concentration is introduced into the measurement process, and for certain metals the limit of detection reaches the absolute value of one microgram. However, in spite of the advantage of high sensitivity, this method has serious drawbacks. One of these is that complexing agents can disturb, or in certain cases even block measurements. Thus, organic materials of natural origin and organics introduced with communal-industrial effluents (emission level) cause strong interferences.

The technology of ion-selective electrode sensors (Di Natale et al., 'Multicomponent analysis of heavy metal cations and inorganic anions in liquids by a non-selective chalcogenide glass sensor array', Sensors and actuators. B, Chemical (Sens. actuators, B Chem.) ISSN 0925-4005), introduced in the 1960s, is also a part of the group of electroanalytical methods. This technology is based on measuring the interfacial potential, which requires a very simple sensor system with a small-sized measurement cell and low energy demand. However, market success of the technology is seriously hampered by the narrow range of available sensors. Stable and sensitive sensors have been developed only for a few simple anions and a few cations. It is also of note that electrodes can only detect non-complexed or aqua-complex ions, which usually represent a tiny fraction in practical samples. Only pH, pCN, pCl and pNH3 measurements have industrial and environmental-monitor applications. The development of sensors based on this technology has come to a standstill, because, although the range of measurable ions widened with the introduction of the latest innovation (liquid ion exchange membranes), the interferences caused by organic materials contained in the samples increased by multiple orders of magnitude. The latter effect may reduce sensor life to 1 - 5 days, after which the sensor membrane and the internal electrolyte system has to be replaced. The development possibilities are limited by the fact that a different sensor and different sample conditioning techniques must be used for the measurement of practically every ion type. Thus, the application of ion-selective sensors for the purposes of wastewater analytics remains limited.

Measurement technologies based on atomic emission and absorption are characterised by the extremely high selectivity of spectrometry, with capability of the simultaneous detection of 10 - 50 elements. High-sensitivity laboratory methods (AAS, ICP) (Kathryn L. Linge, 'Trace Element Determination by ICP-AES and ICP-MS: Developments and Applications Reported During 2004 and 2005', Geostandards and Geoanalytical Research 30 (3), 157-174) can be successfully applied for measuring concentration values below ppm level, but they require thorough sample preparation. In most cases, the sample has to be colloid-filtered and heavily acidified. It has to be underlined that the sample solution can only be introduced into the measurement cell by utilising some type of nebulisation technology (pneumatic, electrospray, ultrasonic, etc.). In addition, these instruments require bottled gases (AAS: acetylene and occasionally oxygen) or inert gas supply (ICP: argon, 10 l / min!) for their operation. Due to the applied 1 - 3 kW high-frequency excitation unit, ICP has very significant power demand.

Graphite furnace atomic absorption spectroscopy (GF-AAS) is a powerful technique suitable for trace analysis. The technique has high sensitivity (analyte amounts 10-8-10-11 g absolute), the ability to handle micro samples (5-100 µl), and a low noise level from the furnace. Matrix effects from components in the sample other than the analyte are more severe in this technique compared to flame-AAS. The precision is typically (5 - 10) % using GF-AAS. The technique is prone to some interference such as background absorption and non-spectral interference.

These sophisticated instrumental analytical methods require thorough sample treatment, which means that the sample has to be measured in a (usually strongly acidic) solution, with high-buffer capacity and high-supporting electrolyte concentration. The need for the above-mentioned techniques makes it impossible to utilise the method for monitoring purposes, due to its high-complexity and high-reagent consumption.

However outstanding the sensitivity and selectivity values are, these advantages are eclipsed by the complex construction and the complicatedness of sample insertion. High energy consumption and the instrument dimensions are common disadvantages in a monitoring application.

Requirement for new measurement technique

Effective checking of heavy metal pollution transmission and emission in the municipal sewerage system required fundamental research work to be done to develop new analytical method which is able to accept such heavily polluted samples, with as little pre-treatment as possible. Also it is advisable to construct a detecting method which is capable of monitoring around and above the limit values - when it detects a pollution peak of value of 2 - 50 times the limit; it can trigger a regular sampler device for the standard laboratory measurement. Furthermore, a device with flow-through system and continuous sampling is required.

Therefore, the basic features of the new analytical method in the project have been set at:

Voltammetric methods
- electrode in contact with the sample,
- measures certain metal forms,
- detection limit from 1 microg,
- multi-metal measurement without special reagents,
- fine filtering required,
- not accept fat emulsion loaded sample,
- low power consumption,
- approximately 2 measurements / hour.

ICP-AES
- no sensor surface in contact with the sample,
- measures all metal forms,
- detection from 1 ppm,
- multimetal measurement,
- fine filtering required,
- not accept fat emulsion loaded sample,
- significant power consumption,
- approximately 10 measurements / hour.

METELCAD
- no sensor surface or optical window in contact with the sample,
- measures all ionic and complexed metal forms without mineralisation,
- measuring ranges approximately 0.1 - 0.2 - 0.3 - 10 - 100 mg / L,
- multimetal measurement without special reagents,
- no filtering required below 0.1 - 0.2 mm,
- wide bore measuring cell against clogging,
- accepts fat emulsion loaded sample,
- low power consumption,
- measurements / hour.

The new measuring principle of METELCAD

The revolutionary new approach in the direct wastewater analysis has been the application of the cathode sputtering effect and optical emission analysis through an atmospheric glow discharge running directly on electrolyte sample as cathode.

Glow discharge is the electric discharge with no thermal electron emission from the cathode (cold cathode discharge). Cathode sputtering is a phenomenon whereby energetic positive ions hit the cathode surface with 50 - 500 eV kinetic energy, destroy the surface structure and produce atoms, ions, clusters and electrons leaving the solution surface.

The cathode sputtering process is the base of the widely used low pressure glow discharge optical spectrometry for surface layer analysis of solid samples. It works in 1 - 3 kPa of rare gas atmosphere that is not applicable to liquid analysis.

The discovery of the proper conditions for the atomic emission of the dissolved and sputtered components of the aqueous solution cathode has led to a new direct water analytical method based on the atom-spectrometry of the emitted light of the glow plasma (electrolyte cathode atmospheric discharge (ELCAD) plasma).

Given that, in electrolyte solutions, the average matrix bonding energy for dissolved components is much lower than in solid phases, the sputtering energy can be set to a low level, that is, the discharge pressure can be atmospheric, which is also very preferable for the water sample.

As a consequence of the above conditions, all the dissolved components (including any complexes) are sputtered while the suspended components are not. The sputtered components are destroyed down to the atomic level and the metal ions are partly neutralised in the discharge plasma by free electrons at thermal energy level; these then receive excitation energies from the high energy electrons near to the cathode. Some relatively stable molecular components like OH, N2, NH, are also excited and produce molecular band emissions. The resulted optical emission spectrum is very simple and contains only the basic atomic lines of the metals and background molecular emissions from the water matrix and the air atmosphere.

The METELCAD plasma forms a 3 - 5 mm high conical shaped discharge at 60 - 100 mA direct current (DC), and sits on the electrolyte sample surface if a W anode is placed above the surface at 3 - 5 mm distance and 1 000 V is applied between the anode and the water sample grounded by an auxiliary electrode. The actual burning voltage is 700 - 900 V, therefore the plasma dissipates only 70 - 80 Watts.

Due to the unique arrangement, the plasma receives only the cathode-sputtered components; therefore it is virtually not disturbed by the non-sputtered components, such as suspended solids and emulsions. To maintain the discharge, a certain electrical conductivity level is required in the solution. The best way to set it is an acidification of the sample by HCl (or any other strong acid) which produces a further advantageous effect by dissolving the metals from the suspended particles. Optimal pH for the plasma is around 1.6. The atmospheric electrolyte cathode discharge (ECD) plasma has a 5 - 7 000 Kelvin electron temperature (electron impact excitations) and a 3 - 7 000 Kelvin gas temperature, so the sample has to flow through the cell with approximately 10 ml / min to avoid boiling.

Monitor development

An analytical monitor is an automatic analyser equipped with automatic sampler and sample treating units and on the output side a data record/data transmission interface to send the measured data to the data acquisition / control centre. Being in serial connection in the measurement process these subunits has equal effect on the quality of the output result, therefore their operation must be of equal reliability.

This means that beside the measuring process, both the sampling unit and the sample treatment unit has to be developed to run smoothly with rough raw wastewater compositions.

Below, the summaries of the developments of the main operational parts and the integration to the monitor instrument can be found

Sampling unit

A submerged pump brings up the raw water with 20 - 50 L / min flow rate into a flow-through a vessel of 25 litres. This vessel is placed beside the METELCAD monitor and contains an innovative system in the analytical sampling technology. Protection of the monitor against clogging of the fluid tubings and the discharge cell has three main measures:

(a) screen filtering at the sample pump (5 x 5 mm filter net);
(b) removing the fibrous and suspended particle materials down to 0.1 mm size while allowing the colloidal components to go into the analytical sample;
(c) keeping the fat / oil particles in emulsion in the tubing and discharge cell.

The screen filter is at the submerged pump where it is backwashed by the returning 25-litre water at the end of measuring cycles.

An innovative new technology in the water sampling for monitors is the centrifugal slit filter (CSF) unit.

The CSF uses the centrifugal force generated by the 500 - 1 500 rpm rotation speed applied to the submerged filtering head of slit structure. The advantages of this arrangement:

(a) self-cleaning effect caused by the shear forces at the outer circular edges of the slits remove the excluded particles and fibrous components from the rotating filter surface;
(b) because of the pressure depression rising in the rotating head a simple and efficient back-flushing can be applied by introducing air or washing fluid into the sampling line while the head is still rotating (practically at the end of the measuring cycle) when vigorous outward radial flushing happens within each slit;
(c) due to the slit size and the low value of the centrifugal force the colloidal particles containing the heavy metals are not filtered out from the sample stream.

For sustaining the emulsified state of fat / oil content in the monitor flow system a simple chemical method is applied, dosing of surfactant to the analytical sample (dishwashing detergent).

Sample treating unit

Sample treating means a procedure to make a sample matrix composition suitable for the analytical measurement process. Treating process is usually a digestion combined with setting the pH value. METELCAD measuring process requires only a pH control to reach the value of 1.7 since the heavy metals are either in acid soluble chemical forms in the wastewaters (hydroxides, carbonates, sulphides) or in dissolved complexes.

According to the requirements the acidification step can be combined with the addition of other solutions in order to prepare the sample for the detection step. A different approach in pH measurement is applied as glass electrode should be avoided in samples loaded with fat, oil and grease emulsions. Acidity is measured indirectly by sensing the conductivity of the flow-through solution. It was found that the value at the required pH is in good correlation with the pH value.

Discharge cell development

The crucial point of the discharge cell is the position of the open surface of the flowing electrolyte (acidified sample solution) in the cathode vessel. Since the physical dimensions of the ELCAD plasma is only 3 - 4 mm between the solution surface and the W anode tip, the cathode level stability must be kept within at least 0.5 mm in the vertical position.

Integration of parts into monitor arrangement

All parts of the monitor must be enclosed in a corrosion resistant house with such arrangement that access is possible for different maintenance purposes:

(a) discharge cell cleaning, anode tip changing or renewal;
(b) optical window cleaning or replacement;
(c) replacement of the tubings in the peristaltic pump heads;
(d) cleaning or replacement of the connecting tubings.

Also, an important integration principle is the proper layout of the flow tubes to ensure the smooth travel of the air bubbles coming in sporadically through the sampling system. Another thumb-rule for analytical automates is that acid-carrying tubes must run at the lowest level of the instrument to prevent severe corrosion damages caused by acid leakage or spill-out.

Validation and calibration results

The METELCAD device was validated according to previously elaborated protocol.
Laboratory tests of the assembled device took place at an environmental laboratory while field tests took place at the sites of respective end-user partners.

Laboratory validations were performed with the following technique:

- Approximately 10 litres of wastewater samples were collected of different composition, the settled samples were filtered on 1 x 1 mm stainless steel net, were acidified using nitric acid and kept cooled until analysis.
- The background total metal concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) (using the strong digestion pre-treatment process).
- Divided to subsamples of 1 L volume, these analysed samples were spiked with increasing amount standard addition of multimetal stock solution (5 mg / L concentration for each metals: Zn, Cd, Cu, Ni, Pb), typical concentration steps were set in the range of background (+ 0.1 to +10 mg / L).
- Spiked samples were measured with the METELCAD monitor, results are the average values of the two standard deviations filtered 10 parallel readings (min 5 readings).

2-sigma filtering: data out of the +/- 2 sigma of the average value (the 95% confidence band) are discarded, new statistics is calculated, and this verification process is repeated until all data of the remaining dataset are in the +/- 2sigma band calibration in raw wastewater.

Validation in raw wastewater

Raw wastewater was collected from urban sewage system in Budapest.
Wastewater was analysed:
- suspended matter approximately 200 mg /L
- COD 90 mg /L
- Conductivity 2120 mS / cm
- pH (original) 6.5

The recovery figures found between 84 - 106 % indicate the proper analytical performance of the METELCAD monitor on static samples.
From the 0 - 4 mg / L plots the LOD for raw wastewater is between 0.2 mg / L (Cd) and 0.4 mg / L (Pb).

Validation and calibration in domestic wastewater

Treated domestic wastewater (effluent discharge) was received from South-Pest Wastewater Treatment Plant in Budapest.
- Organic content as COD: 34 mg / L
- Suspended matter: 22 mg / L
- pH: 7.7

Lab analysis for background with ICP-OES:
- Cu : 0.074 mg / L
- Cd : 0.006
- Ni : 0.052
- Zn : 0.132
- Pb : < 0.034 (LOD)
Standard addition method was used with Cu, Cd, Ni, Zn, Pb.

Applied spiking concentrations for each element were:
- 0.1 0.3 0.5 1.0 2.0 2.5 5.0 7.5 10 mg / L

Based on the results we can say that the LOD values of METELCAD monitor in treated domestic wastewater measurement are:
- Cu, Cd, Zn 0.1 mg/L
- Ni 0.2 mg/L
- Pb 0.3 mg / L

Field tests

The METELCAD monitor was tested in three industrial sites:

(a) at the inflow stream of the Bohumin Steel Work Wastewater Treating Plant (Bohumin, CZ) where the inflow water is characterised as approx. 95 % technology wastewater mixed with 5 % communal load, with sporadic oil contamination (13 - 16 June 2010);
(b) at the outflow stream of the wastewater treating technology at Permastore Ltd (Eye, Suffolk, UK) where the composition was very close to the local tap water used in the technology (16 December 2010);
(c) at the inflow sewage stream of the local treating plant at the Water Services Corporation, Malta, where the composition was characterised as approx. 80 % domestic and 20 % industrial origin in the time period of the investigation (13 - 18 January 2011).

To investigate the performance, the standard addition method was chosen. The concentration of samples was measured against a set of samples of known concentration, similar to using a calibration curve. With this method the matrix effect of the measurement (the background components) is precisely the same in the monitoring and in the standard addition calibration).

1st test at Bohumin Steel Work Wastewater Treating Plant

The raw sample were pumped continuously up to the raw vessel, the CSF unit were operated only during the measurement cycle. The actual sampling frequency was 7 measurements per 2 hours.

When standard addition was applied into the raw vessel, the submerged pump was stopped for 3 measurement cycles then started again to flush the vessel with unspiked raw water. This method is modelling a 'pollution peak' arriving with the inflow stream. For laboratory validation measurement 7 samples were taken during the 'pollution', also before and after the peak.

In the 4 days of the Bohumin testing several grab samples were taken for laboratory control measurements to compare the different analytical approaches to the unknown matrix composition of the water. These METELCAD versus laboratory data diagrams show good correlations, thus, validating the performance of the monitor.

2nd test at Permastore

At this site a multilevel spiking strategy was applied with good correlation between the response functions and the standard additions. Due to transportation technical problems this test was lasting only for 12 hours.

3rd test at WSC in Malta

This site was located within the Water Services Corporation headquarter and local treating facility. The incoming wastewater were dominated by domestic origin. Testing was done by the usual multimetal standard addition to the raw sample vessel of the monitor. The detection performance is good.

Summary of the field tests

The precompetitive prototype instrument was tested in different industrial environments and yielded good responses in detecting pollution peaks of metals in different type of wastewaters. Its unique performance, the detecting ability in the untreated (incoming) wastewaters was successfully proved by the continuous operation through 4 days.

During these tests 300 - 400 complete heavy metal content monitoring analyses (Zn, Cd, Cu, Ni, Pb) were performed to detect pollution peaks in the raw wastewater.

System specification for METELCAD heavy metal monitor for sewerage systems application

Based on a novel analytical method the METELCAD instrument is capable to monitor the heavy metals pollution in untreated sewerage streams of industrial and domestic origin. This unique instrument is developed to detect the pollution peaks caused by accidental and/or illegal waste disposals to the municipal sewerage system.

Maintenance:

(a) cleaning of sampling system and discharge system, 1 week to 3 weeks depending on the level of the organic load (oil and greezy materials);
(b) replacement of pumping tubes from 1 / 3 - 6 months;
(c) replacement of W electrode 1 / 6 - 12 months.

Signal output: trigger contact for automatic sampler to collect preserved samples for laboratory analysis during pollution peak detection

Data output:

(a) local data display;
(b) local data logging for 6 months;
(c) RS 232 for data transmission / uploading;
(d) remote survey access (GSM or net system) for service engineer.

Installation: approximately 4 m2 indoor place, free of H2S or supplied with clean airline, returning pipe for wastewater sample stream (10 - 20 L / min), ventilation below or through ceiling.

Sample connection: submerged pump with 12 - 25 L / min for wastewater sampling line (pump switched on by the monitor for 1 - 2 minutes to flush the sampling system) or gravimetric / syphoning pipe with flow control valve, the sampling head must be prevented by 1 x 1 cm screen.

Potential impact:

Socio-economic impacts of the project

SME end-user proposers PERM, MALEX and PURITY have benefitted from a technology which has the potential to allow them to monitor the presence of heavy metals in their commercial wastewater. Direct economic benefits of the METELCAD technology have also benefitted technological partner SMEs ACON and TISON who developed the product, thereby creating a new base of clients in the industrial and wastewater treatment industries. In addition the partner SMEs, ACON, PURITY and TISON have directly benefitted from the manufacture, commercialisation and maintenance of the system. The METELCAD technology is a unique, economical and environmentally-friendly solution for the wastewater industry EU-wide. This unique product provides the opportunity for consortium members to compete globally in a growing and highly competitive market.

Partners have benefitted through gaining sustainable answers on how to reduce heavy metals in industrial waste waters. As they are able to offer an up to date solution to their industrial partners, partners of the consortium will be able to tap into an increased market share.

Stringent legislation in the form of EC directives continuously creates substantial growth potential for the market aimed at controlling industrial pollution. The project has filled a void in the market, as a result of the Urban Wastewater Treatment Directive (91/271/EC). The on line aspect of the METALCAD technology improves ecological aspects of organisation International Organisation for Standardisation (ISO) and they will have lower costs for wastewater plant entrance.

In addition, the requirements aimed at industries, to comply with strict environmental standards and regulations, also expand opportunities in the field of monitoring and testing of wastewater. The failure of compliance with these regulations could mean heavy fines imposed on industries. Many industries outsource wastewater management to reduce in-house time, resource and manpower devotion to this exercise. Therefore, wastewater monitoring companies have to offer an error-free service in order to remain competitive. METELCAD has provided an opportunity to fulfill these requirements of wastewater management.

SME consortium members will gain economic benefits from the technology through the sale of the system to new member states. The enlargement of the EU through the accession of the new member states has further created an opening for the wastewater treatment market. These countries have previously allowed untreated water from industries to enter their waterways, however the increasing competitiveness amongst industries within the EU, means that the management of industrial waters has become crucial and guarantees the survival of the wastewater monitoring and management sector.

SMEs are able to target wastewater management companies that recycle sewage and industrial wastewater for market niches. Estimates predict the EU wastewater business to grow up to 14 times its current size.

METELCAD can also provide a significant improvement for the commercial wastewater sector, particularly in the recycling of sewage sludge for farming, as a low cost replacement for fertilisers. There is significant value in the agricultural sector for compounds found within wastewater (including organic matter, nitrogen, phosphorus and potassium, and to a lesser extent, calcium, sulphur and magnesium). Sludge is a compound which includes both pollutants that can be broken down into harmless molecules and others that cannot, these include heavy metals.

SMEs have envisaged that the successful METELCAD project could lead to a total economic impact of EUR 1.75 million over a 5-year period, meaning a return on investment ratio (ROI) of 1:5 for the partners. From the EC investment perspective METELCAD means benefits related to shorter processing times and a reduction in waste for all EU users of the system, which in turn means savings in production costs. This is projected to result in a return on investment ratio of 1:14 for the EC over the same 5-year period.

Societal impacts

The METELCAD project is suitable to provide a significant direct impact on the society and communities, through the monitoring of heavy metals is wastewater. It thereby prevents any reuse of unwanted dangerous effluents. There have been investigations into the portion of heavy metals in subsurface waters and the soil environment. Heavy metals are proven to have dangerous effects on human health, 27 % of global disease is caused by environmental exposures to toxins, such as mercury, which can damage the central nervous system, resulting in sensory impairment and lack of coordination. METELCAD can highlight the level of heavy metals, thereby drawing attention to the fact that some wastewater is too dangerous to remain untreated or be reused. In addition, the high costs of wastewater treatment has previously led to the direct reuse of untreated or partly treated effluent in irrigation, thus further aggravating pollution and health concerns. It is therefore not surprising that consumer concerns regarding the exposure to substances such as heavy metals are at an all-time high. Especially, when the health implication of such exposures can be avoided by well-targeted interventions and improved technology.

The implementation of the new technology will lead to increased safety of the job. Professionals will make savings on time and will be more accurate, optimising resources thereby creating competitiveness and profitability. The proposer SMEs of the METELCAD project will help in the commercialisation of the eco-technology that finds the right balance between environmental awareness and market competitiveness. There will also be broader economic impacts associated with the reduction of wastewater pollution.

Despite the efforts of the newly acceded EU countries to prepare themselves for the EU accession, resulting in progress in many areas, they are still lagging behind in some key areas, including pollution control. These countries need to invest between EUR 50 billion and EUR 80 billion to bring their environmental standards to the required EU-wide levels (according to the EC). The use of METELCAD will not only raise quality standards in one country, but across Europe thanks to the common market. This can lead to further cohesion and uniformity of standards.

The technology also provides space for collaborative opportunities and the ability to share knowledge between the professional users within the wastewater management sector, by providing a forum for discussion and the exchange of experiences, information and ideas. The technology can have a direct impact on the quality of life in the Community as a whole, by raising awareness and environmental standards.

The METELCAD technology will also meet one of the major aims of the Lisbon strategy, as highlighted in a Commission report on Environmental Technology and Sustainable Development. Through fostering technological progress the project contributes to the advancement of innovation and the development of technologies that improve efficiency in the use of resources and reduced emissions.

In addition, the effective use of METELCAD can contribute to European ambitions of being a driving force in responsible production practices of industrial pollutants. Other parts of the world also strive to shift towards an environmentally friendly, but at the same time economically competitive use of these substances, for which the EU can be an example, with the help of METELCAD.

Dissemination activities

Dissemination activities took place to ensure that the results of the project would be spread beyond the consortium members to a wider audience. Transfer of knowledge outside the consortium was coordinated by the exploitation manager; however, specific actions were designated between the partners. Before any material was published, all partners discussed and decided the content of the material that could be disclosed, to ensure that no confidential information would be publicised.

Amongst the dissemination materials were leaflets, posters and CD-ROMs. An interactive multimedia user guide was also made for the system, to enable a wider audience to use the METELCAD system. It was also planned that project related mailing would be carried out at intervals, which was the case, especially in the Czech Republic and in Malta.

The development of the prototype system was a valuable tool for the dissemination of METELCAD. The prototype was tested at three different locations for a week each time, to ensure full functionality of the system.

There was constant contact throughout the project between partners about the dissemination plans and actual dissemination results. As a result the promotion of the technology developments to customers and industrial contacts was targeted and carried out. Examples of further promotion to a wider audience were at related conferences, where the prototype product was taken and presented, such as at the Water Treating Conference (Nemzeti Víztechnológiai Platform Szakmai Fórum) in Budapest in September 2010; the International Conference on Water 2010 (Water supply, Quality and Water protection) in Kolobrzeg, Poland; and the 'Automatic online measurement of the concentration of heavy metals Zn, Cd, Cu, Ni, Cr, Pb in wastewater, 24 Sludge and Waste Conference', 23 - 24 June 2010, Brno, Czech Republic.

Partners of the consortium had various plans for the use of the final working system. Nearly all the consortium members had direct benefits from the product, whilst others had indirect benefits therefrom. Several partners decided to take the METELCAD system into their product range or represent the system in their countries, whilst others would only help in the promotion of the product in some specific countries. Various plans were worked up about the marketing of the system for example, some partners thought it best to loan the system out for demonstrations to best promote it in several companies.

Exploitation of results

The exploitation agreement mainly reflected the definition and handling of background knowledge and the conditions by which the consortium would grant further manufacturing and distribution outside the consortium to meet the demand from the end users. Licensing arrangements and protection of intellectual property generated within the project and the methods of dissemination were also included. During the whole life span of the project, discussions took place among the partners regarding the market strategy of the equipment.

It was agreed that all SME partners would retain the full ownership of the patent on the ECD and the METELCAD prototype. After a request by SMEs that the research and technological development (RTD) partners should actively participate in training and dissemination activities given their expertise, RTD partners ensured that SME participants receive full ownership and exploitation rights of the results generated by the project. This was achieved through an elaborated knowledge transfer plan including three training sessions at various locations and easy access to all the knowledge generated during the project through the restricted parts of the METELCAD website.

Each partner declared his existing knowledge in the consortium agreement for the purpose of undertaking the project. All members have additionally agreed to grant, amongst themselves, free access to their relevant background knowledge for the purpose of enabling all partners to fulfil their research obligations within the project. The exploitation manager of the project, in collaboration with the partners, wrote a JOA which was accepted by all partners.

Members of the consortium formulated their intentions on the future usage of METELCAD at the final meeting. They decided to implement a business plan for the next seven years. Two more METELCAD devices are in the process of being manufactured, one system with the same specification as the prototype, dedicated to wastewater and a further system that is dedicated to clear water. The plan is to target European wastewater companies, water analytical companies and companies treating waters with high heavy metal concentration. Through the extensive personal business networks of the project partners, who have been in this field for a remarkably long time, the sales success potential of the system is high. Additionally, the continuous need for new monitoring equipment, following European regulations and directives (which are getting stricter), and their strong positions in different industrial areas gives strong confidence to the SME partners to make future plans related to further development. PERMASTORE LTD, has a strong worldwide market in which METELCAD can be involved. Furthermore, PURITY and MALEX have relations to Czech, Slovakian, Polish, and German markets. Finally, TISON is one of the key service providers and distributors in the Scandinavian market.

The partners expect the manufacturing price of the product to radically fall after implementing serial production. It is of key importance to distribute the product and services related to it at a competitive price. The price of parts and labour were compiled, but the price of maintenance and changeable parts had to be known too to calculate the final prices. The partners accepted the retail price of the system, (calculating with a profit margin of 60 %) to be EUR 9 600. Another business line to which partners agreed, was to rent out the system at a price of EUR 250 / month (including a 70 % profit margin).

Assuming the slow increase of surface-water treatment and wastewater plants, the effective number of end users is thought to be around 68 000. Thanks to the unique features of the METELCAD appliance as well as the significant size of the target sector and the well-structured distribution channels of the partners, the consortium intends to penetrate into 2 % of the market by 2015 which means 1 227 appliances to be sold in that year.

List of websites: http://www.metelcad.eu

Coordinator: MFKK Innovation and Reserach Center LTD
Tétényi út 93
1119 Budapest
Hungary
Tel.: +36-178-74024
Fax: +36-178-74390

Project technical coordinator: Dr Attila Wootsch
Project manager: Szabolcs Gyarmati

Related documents