Sea Technology, October 2001 - Marine Electronics
A study undertaken by Aquatic Sciences Inc. (ASI) has demonstrated that under test conditions, the Scalewatcher® Electronic System can successfully control the settlement of zebra mussels. Pilot-scale application of the technology will determine if zebra mussel settlement in pipes and water inlets can also be successfully controlled. The research, commissioned by Scalewatcher® North America Inc., was carried out over a six week period along the Welland Canal in Southern Ontario, where densities have historically exceeded 20,000/m^sup 2^. Results showed that the Scalewatcher® system had reduced the amount of molluscs by up to 97 percent.
The impact of zebra mussels now extends from the Great Lakes watershed to the mouth of the Mississippi River. They affect industry and smallvolume water users by clogging pipes and intake structures. Industries in infected areas regularly treat the water with oxidants, heat or molluscides to eradicate zebra mussels from the service water system. Heightening awareness of aquatic environments and health issues has resulted in increased regulations and lower discharge limits for chemical treatment, resulting in industry now requiring alternative methods to control infestations.
The Scalewatcher® system is extensively used in industry throughout the world to control fouling resulting from the build-up of scale. Industries in Japan found that the system controlled not only scaling but also crustaceans in the piping system to a heat exchanger. This observation led Scalewatcher® North America Inc. to hypothesize that the Scalewatcher® system may also control zebra mussels.
ASI set up a study to determine where the Scalewatcher® system inhibits zebra mussel settlement compared to a control system. Using a research trailer, ASI installed a 200 gallon head tank filled with canal water at the north end of the trailer. The test and control systems were gravity fed by the head tank. The control chambers were connected to the ball valve outlet and the Scalewatcher® test system and chambers were connected to the gate valve outlet. Electrical leads from the Scalewatcher® unit were wrapped around the steel pipe, which in turn was connected to the test system, which consisted of a set of three test chambers (bioboxes) simulating the zebra mussels' preferred colonization environment.
Technicians took measurements daily recording conductivity and water temperature for the control and test systems. At the end of the test, the culture plates were removed and samples taken for analysis. It was found that the density of the zebra mussels on the plates treated by the Scalewatcher® unit was 10 times lower than the control. These results indicate that the Scalewatcher® unit inhibited the settlement of zebra mussels.
The Scalewatcher® unit controlled both pediveliger and juvenile zebra mussels, which suggested to ASI that the system might change chemical partitioning of calcium in the water and cause settling larvae to perceive an unsuitable environment.
Scalewatcher®'s patented technology works by producing a complex frequency modulated waveform. Reacting to the varying applied field, the Scalewatcher® creates an induced electric field inside the pipe, whereby the crystal growth of the scaling in the water is promoted.
Copyright Compass Publications, Inc. Oct 2001. Source of article located HERE
Provided by ProQuest Information and Learning Company. All rights Reserved