Chemical Control Strategies Highlight EPRI Conference

From January 31, 1991 (update #6)

ORLANDO, Fla. Both chemical and nonchemical control strategies were described at the Electric Power Research Institute's International Macrofouling Symposium Dec. 4-6, according to Dave Michaud of the Wisconsin Electric Power Company. U.S. Environmental Protection Agency officials also presented their perspective on potential chemical control strategies. The objective of the EPRI symposium was to provide a forum for exchanging information on macrofouling problems - especially zebra mussels - at various power plant sites. Most experience in the use of chemicals for macrofouling control, particularly for zebra mussels, involves the use of some form of chlorine. Early reports indicated a need to provide a continuous dosage of chlorine to prevent settlement and attachment of the zebra mussels; however, several plants have had success in using intermittent treatment strategies. Research is under way to determine if intermittent chlorine treatment levels can reliably prevent zebra mussel fouling. Chemical manufacturers such as Betz, Buckman, Calgon and Nalco have products purporting to provide effective and environmentally sound zebra mussel control. The U.S. EPA is cautiously allowing demonstration of these products as environmental fate data are developed. Although some of these proprietary chemicals have been used previously for blue mussels, Asiatic clams and other macrofouling organisms, chemical applications are still being refined for zebra mussel control. EPRI is in the process of testing a variety of conventional chemicals, but it did not reveal the chemicals because some combinations may be patentable. EPRI members can, upon request, obtain further details. Some success is anticipated with antifouling paints and coatings for surfaces susceptible to fouling, based on saltwater experiences. Nontoxic, nonfouling siliconized oil paints and some copper-based paints have proven successful for macrofouling organisms. Ontario Hydro is testing coatings for specific application to zebra mussel settlement prevention. Thermal treatment has also proven to be a successful control technique for zebra mussels. U.S. EPA officials warned that utilities must meet state water quality standards for discharges of biocides or water treatment chemicals. If the U.S. EPA believes that state standards would be exceeded, the agency has the authority to object to the issuance of a permit. The EPA is requiring effluent toxicity testing (biomonitoring) - generally done at an off-site laboratory - and has required on-site biomonitoring for nonpersistent chemicals. The agency is working with chemical vendors to develop acute and chronic toxicity data to establish numeric water quality standards for biocides and water treatment chemicals used to control zebra mussel fouling. EPA officials also pointed out that biocides must be registered by a manufacturer as required by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Products can only be used in systems for which they are specified and for the purpose(s) specified under such registration. They noted that FIFRA registration does not constitute approval for use. Facilities wishing to use a biocide must obtain permit approval before new biocides can be discharged.

ID: 19910131-5.

The Zebra Mussel Update was a 4- to 8-page quarterly national newsletter published by the University of Wisconsin Sea Grant Institute from May 1990 through May 1997. The ZMU documented the spread of the zebra mussel -- an exotic nuisance mussel -- through North America's freshwater environments, especially the Great Lakes, and on efforts to control it.