Control of zebramussels using sparker pressure pulses

Field tests of a sparker system demonstrated control of zebra mussels in an intake pipe. The sparker was implemented in a wet well near the exit of an intake pipe at a Georgia-Pacific plant on Lake Champlain, N.Y. and was tested during the summer of 2003. The pressure was measured at several locations along the pipe, and zebra mussel samples were placed at those locations. Test results indicated that sparker pressure pulses can eradicate existing adult zebra mussels and prevent the settlement of larval stages. Sparker pressure pulses with peak pressures of at least 0.04 MPa and pressure energies per unit area of 0.16 J/m 2 per pulse appeared to prevent the settlement of veligers. Peak pressures of 0.23 MPa and pressure energies per unit area of 5.8 J/m 2 per pulse caused mortality of adult mussels. Z ebra and quagga mussels belong to the dreissenid family of nonindigenous invasive mussels found from north of the Great Lakes to the mouth of the Mississippi River in the south. The mussels are also found in Nevada, Arizona, California, and Colorado. Dreissenid mussels cause serious problems by clogging fixed screens and other system components in contact with raw water. The Nonindigenous Aquatic Nuisance Prevention and Control Act and its amendments mandate control of dreissenid mussel infestations (NISA, 1996; NANPCA, 1990). Although several control strategies are available, none is applicable to all situations or entirely problemfree. Chlorine effectively controls dreissenid mussels but produces disinfectant by-products, some of which are carcinogenic. Mechanical removal is also effective but is costly and may require plant shutdown. A nontoxic alternative uses pressure pulses to prevent the settlement and growth of dreissenid mussels and could also eradicate adult mussels. The technique reported here uses intense pressure pulses from a sparker. The pressure pulse is generated by high-power electrical arc discharge (pulse) between electrodes in water. The concept is illustrated in Figure 1. A pulsed electrical discharge rapidly heats and vaporizes liquid between two electrodes, producing a pressure shock. The emissions leave behind a high-pressure vaporized water cavity or “bubble,” which expands to a maximum diameter and then contracts and collapses, producing another pressure pulse. This expansion and collapse repeats until the energy in