High-charge cationic coagulant dimethyl diallyl ammonium chloride (DMDAAC) compounds have been used in water treatment plants as flocculators and clarification aids (Blanck, Mead, and Adams 1996), and have become the first molluscicide approved by the U.S. Environmental Protection Agency for use in domestic potable water systems. The various VeliGON formulations of these compounds differ in their molecular weight and cationic charge density. Floc allows settling out of veligers, and affects adults (Waller et al. 1993). The use of this compound in water treatment plants at concentrations for zebra mussel and Corbicula veliger control has been shown to reduce or eliminate the amount of alum coagulant required at the rapid mix area. This aids liquid/solid separation operations, resulting in less residual solids and soluble aluminum (sludge) in the plant effluent, and higher pH of finished water. The reduction in alum usage can improve the stability index and allow longer filter runs. Individual users must obtain specific discharge permits.
Chemical Name and Commercial Formulations
Mode of Action
Timing of Application
Maximum Water Concentration
Timing and Appearance of Effects
Field Instructions and Guidance on Operational Applications
Zebra Mussel Chemical Control Guide