Several compounds with toxic biocidal oxidizing activity that are already widely used as disinfectants in treatment of drinking water and wastewater and in power plant facilities to remove slime and biofilms are highly effective on zebra mussels. The environmental effects and requirements for safe discharge are well understood by users and regulators. While oxidizers present problems because of their corrosive effects on metals, their low cost makes them very attractive in mussel control programs.
The major types of oxidants frequently used for chemical control of biofouling and available as generic chemicals for molluscicide use are listed in Van Benschoten et al. (1993):
In general they have similar modes of action based on the oxidation of organic matter, which leads to toxic and lethal effects. They are suitable for use in preventative treatment, where they are added to a system throughout the breeding season at from 0.1 to 0.5 mg L-1 (ppm) total residual oxidant (TRO) to prevent settling. For reactive treatments, continuous application of 0.5 to 1.0 mg L-1 TRO for 2 to 4 weeks can eliminate established adult colonies, but concentration and contact time required depends on temperature, water chemistry, and physiological state of the zebra mussels. Mussels do detect oxidants, and shell closure for up to 2 weeks may reduce efficacy in adults (Claudi and Mackie 1994).
While chlorine dominates all chemical use for zebra mussels, there has been concern that there will be additional restrictions on its discharge in the future due to its nonselectivity and its formation of undesirable by products such as trihalomethanes (THMs) and chloramines upon coming into contact with organic compounds in open water. This will change the picture for chemical control of zebra mussel. Dechlorination can be achieved by addition of sodium sulfite (Barton 1993). While ozone and hydrogen peroxide are not dealt with in this user guide, toxicity to zebra mussels is summarized by Electric Power Research Institute (EPRI) (1993).
Zebra Mussel Chemical Control Guide