|
|
|
|
Tools
Mobile laboratory, biofouling monitor, mussel monitor, BioGEORGE, micro- and mutatox, ATP/MIC tests, fish deflection systems, pulse chlorination and DATS
|
|
|
Pulse-Chlorination®
In the Netherlands, chlorination is still the most commonly applied method used against fouling (macro and micro fouling) in cooling water. The species to mitigate are marine, brackish, and freshwater mussels, hydroids and barnacles. Especially mussels are the cause of the main problems.
In 1998 KEMA developed a new regime of chlorine dosing called Pulse-Chlorination®, combining optimal anti fouling results with the lowest amount of Na-hypochlorite. In the summer of 2000 during the Integrated Pollution Prevention and Control (IPPC) meeting in Sevilla (Spain), Pulse-Chlorination® was declared as BAT (Best Available Technology).
At this moment Pulse-Chlorination® has been sucessfully applied in: the Netherlands, South-Korea, Qatar and Australia.
Pulse-Chlorination® is based on the principle that in general mussels and clams have a recovery period before full opening and start filtering after exposure to a chlorination period. The method takes advantage of this recovery time by using short successive periods of chlorination, alternating with periods without chlorine. The tests applied between 1998 and 2003 resulted in a saving of chlorine use up to 50% on yearly basis, compared to the regimes applied in earlier years. It is evident that Pulse-Chlorination® is an improved method for the control of macro fouling. The result is a better overall performance of the cooling water system and therefore less maintenance is necessary. This in turn allows longer intervals between planned outages, bringing down the costs of these outages of approximately € 50,000 per day spread out over three years rather than two years. As a result of the decreased chlorine usage, the impact on the environment will be reduced. Fewer chlorination by-products (CBPs) will be emitted in the outfall.
For more information download the brochure and publications below or contact us.
|
|
|
|
[download] Pulse-Chlorination (.pdf 298 kb)
|
|
|
[download] Pulse-Chlorination Qatargas (.pdf 245 kb)
|
|
|
[download] Ecological Conditioning and Optimisation of a Once-Through Cooling Water System (.pdf 499 kb)
|
|
|
[download] Pulse-Chlorination, the best available technique (.pdf 811 kb)
|
|
|
|
BioGEORGE™
Fouling by microorganisms, i.e. biofilms, in cooling-water systems is one of the most important causes of heat transfer reduction in heat exchangers. Indeed, the occurrence of a biofilm in heat exchangers amounts to an estimated annual loss of some billions of Euros on a global scale. Also, biofilm activity in cooling-water systems increases the risk of corrosion damage by MIC (Microbially Influenced Corrosion). Furthermore, the occurrence of pathogens in biofilms and circulation water, like Legionella and Acanthamoeba, increases the health hazards of employees working near recirculating cooling water systems. In order to mitigate both waterborne micro-organisms and biofilms, biocides and additional chemicals are applied on a large scale. The BioGEORGE™ on-line monitoring system registers the actual status of the formation and activity of a biofilm and provides an early warning of unsatisfactory conditions. As a result, it is possible to optimize the biocide dosing applied by providing feedback directly to the operator, potentially reducing costs. In addition, a controlled biofilm reduces all microbial effects, such as MIC and reduced heat exchange, to an optimum. The system is used by KEMA to alert operators to the necessity of water treatment or to assess the effectiveness of a water treatment regime, thereby minimizing the risk of fouling and corrosion while reducing the costs of the mitigation approach. BioGEORGE™ is a trademark of Structural Integrity Associates, Inc. Applications: - optimization of water treatment regimes in recirculating and once-through cooling water systems
- solving MIC (Microbiologically Influenced Corrosion) and Legionella related problems.
|
|
|
Mobile water laboratory
The KEMA mobile laboratory is a rebuilt 20-foot sea container with a wet part (lab for experiments) and a dry part (office). This mobile laboratory is placed on-site at your company, so tests on cooling water conditioning can be performed under local conditions.The lab space is designed to perform research on location with cooling, waste or process water. The standard equipment of the lab consists of a water supply system with three flow-through drums in which the flow can measured and adjusted on-line. Besides flow measurement, turbidity, pH, dissolved oxygen, salinity, temperature and TRO or FO are measured on-line. In the office the necessary PC’s, communication systems and air conditioning are installed. The acquired data can be transmitted by cellular phone to KEMA headquarters for further data analysis.
|
|
|
KEMA Biofouling Monitor®
Monitoring of settlement and growth of unwanted organisms and the efficacy of mitigation procedures applied is an important issue in cooling water fouling control.
KEMA has developed a new monitor, the KEMA Biofouling Monitor® (KBM), in response to the demands of the operator. Design priorities were easy sampling, clearing of sedimentation and the prevention of flooding of the monitor. This is all achieved by using an up-welling flow through four PVC tubes, via a sedimentation chamber, and a central outlet. The settlement occurs on four plates hanging in these tubes. No interruption of the water supply is necessary during sampling.
The KBM is compact (diameter 400 mm; height 1040 mm) and made of recycled PVC. Extra options are available: flow measurement, oxygen and temperature probes. The monitor is connected as a by-pass loop in the cooling water system and duplicates the fouling patterns of mussels, oysters, barnacles and hydroids in the system.
The result is a well-defined fouling sequence in the monitor, which allows detection at an early stage, permitting enough time for countermeasures.
Applications:- Measurement of the efficacy of the anti-fouling treatment applied
- Continuous overview in the fouling sequence during the seasons
- Testing of coatings and new anti fouling applications
- The KBM can be used for eco-toxicological studies.
|
|
|
Mussel Monitor®
The Mussel Monitor® is a valve movement apparatus with which the behavior of mussels and oysters can be followed during a biocide dosing test. This tool is the result of co-operation between TNO, RIVM and Delta Consult. The Mussel Monitor® is a commercially available Biological Early Warning System (BEWS). The method is based on the valve movement behavior of bivalves like mussels and oysters. In unpolluted water the valves open and close following a rather regular pattern during which they are open for most of the time, i.e. filtration for feeding and oxygen uptake. After encountering a pollutant like a Na-hypochlorite dosing, the mussel will show a change in behavior, closing up for longer periods or extra high activity in closing and opening of the valves. On top of the Mussel Monitor®, eight mussels are fixed with one valve on a PVC backplate with a sensor attached. The other sensor is fixed on the free moving valve. The measurement principle is based on inductive distance measurement at 250 kHz, enabling an accurate distance measurement between the valves of less than 100 micron. With a microprocessor, the valve movement behavior of the eight mussels is sequentially registered resulting in a fast reacting BEWS. Nowadays the Mussel Monitor® is used by KEMA in water quality surveillance and for optimization of anti-fouling procedures, like Pulse-Chlorinaton® in industrial cooling water systems.
|
|
|
Fish deflection systems
Fish are killed when they pass through the turbines of hydropower stations and are drawn into the cooling water intakes of thermal power stations and other industries. Optimal plant operation is disturbed by piled-up fish at cooling water screens. Also, several fish species indirectly promote noxious algal blooms in drinking water basins. Deflecting fish from such systems and danger zones has become increasingly important to plant operation, ecosystem sustainability and current environmental requirements, as legislation becomes more and more strict.
KEMA has extensive experience in the research and development of fish deflection systems based on light that have proved their value in practice. Experiments in the past few years have demonstrated that certain fish species can be deflected effectively from the danger zone by means of a light screen. Beside the light systems, KEMA is the official contractor (for the Benelux and Germany) of the effective acoustic fish screens developed by Fish Guidance Systems Ltd (UK). Both the light and sound systems can be used by KEMA to solve your fish-related problems.
KEMA biologists and engineers can tell you which system is best suited to your specific situation and, after installation, perform follow-up research in order to demonstrate the results achieved. We deliver a complete, tailor-made operational system adapted to any environment, from lake to sea. Parameters to be considered include background lighting, background noise, water velocity and water turbidity and, of course, the specific (target) fish species involved. The systems come with easy-to-operate hoisting and tension regulating gear.
Light systems
KEMA developed new strong strobe lights, placed in underwater luminaires consisting of a glass cylinder on a PVC pedestal. Within the glass cylinder, a strong flash tube is fixed with accessory capacitor bank and electronics. The flash tube is fixed on an aluminum screen, serving as a reflector. The light of the lamp is bright white with a wavelength between 400 and 700 nm. The lamps, installed in a row in front of the danger zone, produce synchronous flashes the frequency of which can be controlled through a control unit. By means of heat sensors, the lamps are protected from overheating (max. 50 ºC).
Strobe lamps |
Frequency (n/s) |
Capacity (Joule) |
Reflector |
Light intensity at 1 m distance (Lux) |
New lamp (KEMA) |
6 |
23 |
+ |
200 – 800 |
Old lamp (KEMA) |
6 |
2 |
- |
13 – 19 |
The fluorescent lights, also developed by KEMA, exist in the same underwater luminaire, only the lamp fixed in the glass cylinder is a PL-L 36 W lamp (230V/50Hz; Luminous flux 2900 Lm (100 h burning); 435 mA).
|
|
|
Microtox® and Mutatox™
The Microtox® test is an acute toxicity test with the marine luminescent bacteria Vibrio fisherii. It is a widely accepted method for the determination of acute toxicity, standardized in various countries (i.e. NVN 6516, DIN 38412 en AFNOR T90-320). Several articles describe the test method including the ‘Handbook of Ecotoxicological data Vol. II’.
The Mutatox™ test is considered a promising tool for detection of mutagenic compounds in environmental samples. The genotoxicity of water samples can be determined with Mutatox™ Genotoxicity Test System (Microbics Corporation, CAL U.S.A.).
KEMA already has more than 10 years’ experience in the application of both methods and we are fully equipped for testing water samples in Europe and from abroad.
Microtox® toxicitY test
In the Microtox® test, the light inhibition of luminescent bacteria is measured after a short exposure time of 5 minutes to water dissolved contaminants. The exposure time can be adjusted and extended to 15 or 30 minutes, depending on the type of contaminants expected. The measured light emission from luminescent organisms is a well quantified physiological effect parameter. The test bacteria (Vibrio fisherii) are (standard) freeze dry commercially available organisms. An important advantage of biological warning systems using bacteria is the stable response enabling statistical alarm settings.
Mutatox™ toxicitY test
Mutatox™ utilizes a special non-light active mutated strain of the luminescent bacteria Vibrio fischeri (M169). This species shows an increase in luminescence at exposure to sub lethal levels of mutagenic compounds. The test is carried out with and without S9 rat liver microsome fraction. With S9 addition, plus co-factors, it is possible to demonstrate compounds with genotoxic action after metabolism by liver enzymes. The emitted light is measured with the Microbics Model 500 analyzer after 16, 20 and 24 hour incubation at 27°C in a thermostatic water bath. A sample is considered as positive ("genotoxic") when in at least two successive test concentrations – at a 1:1 dilution – the measured light emission levels are a factor 2 higher compared to the control.
|
|
|
ATP and MIC tests
Microbially influenced Corrosion test: MICkitIII™
Microbially influenced corrosion (MIC) turns out to be, on an ever-increasing scale, an important factor in degradation phenomena (corrosion) of metal piping, conduits and constructions in electricity plants, (petro)chemical industries and oil and gas production. MIC occurs because of the existence of a biofilm, in which the growing bacteria excrete corrosion-inducing metabolic products. Monitoring these bacterial species provides the operator with a warning that countermeasures should be taken in order to prevent MIC, before detrimental effects arise. The MICkitIII™ used by KEMA is a 'batch' type measurement, specifically aimed at the most significant MIC-inducing bacteria.
MICkit III™ is a trademark of BioIndustrial Technologies, Inc.
Adenosine-5'-triphosphate test
Adenosine-5'-trifphosphate (ATP) can best be described as the energy-carrier in all living cells. The ‘Test-Kit’ is specifically designed by Celsis Lumac in order to determine the level of microbial contamination in water samples and swab samples from surfaces, by which the effectiveness of additives and biocides on microbial growth can be determined. The 'Microbial Biomass Test Kit' can be applied to all industrial systems in which information is needed on the level of microbial activity. Within the test, the amount of light production correlates with the amount of ATP in the sample, which in turn is a relative measure for the microbial activity. The advantage of this test is the short determination time of several minutes.
|
|
|
Deposit Accumulation Testing Monitor
The DATS™ monitor provides vital information regarding performance degradation, chemical efficacy, and economic losses due to chemical/biological fouling, i.e. biofilms, scaling and sediment. The tube alloy and dimensions, heat flux and flow velocity of process equipment automatically calculate the heat transfer resistance. Changes over time accurately reflect the accumulation of the fouling deposit. The system is used to evaluate the performance of the condenser in order to optimize the applied water treatment for optimal heat exchange.
The Deposit Accumulation Testing System (DATS™) by Bridger Scientific Inc. (US) is a microprocessor-based data acquisition system used by KEMA to control, monitor and report all parameters necessary to perform heat transfer analysis at specific operating conditions. As deposits (scaling, microbial slime, sediments) accumulate, the tube surface becomes thermally insulated, and the change in Heat Transfer Resistance is electronically reported. Specific operating conditions such as heat load, type of material, tube diameter and flow rate are controlled by the DATS™ to mach specific components of the cooling system.
Using the DATS™ allows the customer to analyze fouling for specific process conditions, and generates information necessary for efficient fouling management programs.
For more information please contact us.
|
|
|
|
|
|
|
|
|
