Final Report: Nontoxic Sparker Control of Zebra Mussels

EPA Contract Number: 68D01040
Title: Nontoxic Sparker Control of Zebra Mussels
Investigators: Schaefer, Raymond B.
Small Business: Phoenix Science and Technology Inc.
EPA Contact:
Phase: I
Project Period: April 1, 2001 through September 1, 2001
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2001) RFA Text |  Recipients Lists
Research Category: Watersheds , SBIR - Water and Wastewater , Small Business Innovation Research (SBIR)

Description:

Following its inadvertent introduction in Lake St. Clair in the late 1980s, the zebra mussel (Dreissena polymorpha) quickly spread throughout the Great Lakes and into many inland lakes, rivers, and canals. Because the zebra mussel tolerates extreme crowding, it clogs intake pipes, filters, trash racks, and other components of ships, dams, pumping plants, and hydropower facilities that use freshwater and has become a serious problem. Chlorine injection effectively controls zebra mussels, but also produces toxic byproducts, some of which are carcinogenic. Furthermore, regulatory actions in the United States and Canada may reduce or eliminate chlorine for controlling zebra mussels. This Phase I project, combined with work supported by the U.S. Army Corps of Engineers, demonstrated the feasibility of using high-intensity pressure pulses from sparkers for the nontoxic, low-cost control of zebra mussels.

Sparkers work by releasing stored electrical energy between two submersed electrodes, producing a high-intensity pressure pulse that can either clear away mature zebra mussels by interfering with feeding or inhibit young zebra mussels from attaching to surfaces. In the control concept investigated in this project, a sparker source is tethered near the entrance to a pipe that is to be kept free of, or cleared of, zebra mussels.

A sparker was introduced in 1992 by another company, but has seen little use because of electrode maintenance issues, and cost, and because scientific data establishing its effectiveness were lacking. In this project, the feasibility of developing a new low-cost and low-maintenance sparker was investigated experimentally in laboratory tests. Also, field tests were conducted in which test samples were placed in water intake pipes during a zebra mussel growth season, and pressure pulses from the sparker were measured for correlation with zebra mussel response. These field tests were the first that combined zebra mussel response tests with measurements of sparker pulses at the locations of test samples.

Summary/Accomplishments (Outputs/Outcomes):

Field tests conducted by Phoenix Science & Technology, Inc., at two sites on Lake Champlain, NY, showed that sparker pressure pulses generated near the exit of water intake pipes prevented growth of new zebra mussels for approximately 125 feet into the pipes. Also, the test results showed adult zebra mussels being cleared away for approximately 50 feet into the pipes. The pressure levels and corresponding acoustic spectra producing these effects on the zebra mussels also were measured. In addition, the propagation of the pressure pulse in the pipe showed effects associated with pipe cutoff frequencies and the fundamental frequencies of the sparker pulse.

Laboratory tests showed that the sparker currently in use is inefficient. A new sparker design will have an efficiency of more than a factor of 10 higher than the current sparker. Also, new electrodes were tested, which have a lifetime that is four times longer than the electrodes in the current sparker. A new sparker system with high efficiency and new electrodes will operate for at least 1 year before needing electrode replacement instead of every 5 weeks, as in the current sparker.

A new prototype sparker system for zebra mussel control was designed, with an estimated capital cost of approximately 40 percent less than the current commercial sparker. Also, maintenance costs will be reduced because of increased electrode lifetime. The cost of the new sparker system will be less than that of chlorine injection systems, which will promote commercialization.

Conclusions:

Based on this project, a sparker system for controlling zebra mussels is both technically and commercially feasible. A sparker can be developed during Phase II that effectively controls zebra mussels at a reduced cost compared to chlorine. This new prototype sparker will be used in field tests to continue to determine sparker operational requirements for the wide range of pipe diameters, pipe lengths, flow rates, and other parameters at zebra mussel problem sites. Commercial feasibility of sparker technology is supported by the environmental benefit of reducing the disinfection byproducts generated by chlorine systems currently in use. Sparker technology, in addition to use for controlling zebra mussels, has widespread commercial potential for many types of biofouling organisms. A successful program will result in a nontoxic, practical, low-cost sparker for controlling zebra mussels and for other antibiofouling applications.

Supplemental Keywords:

sparker acoustic source, zebra mussels, nontoxic, biofouling control., RFA, Scientific Discipline, Toxics, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Sustainable Industry/Business, exploratory research environmental biology, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, HAPS, Ecological Effects - Environmental Exposure & Risk, Environmental Monitoring, New/Innovative technologies, Engineering, Chemistry, & Physics, Environmental Engineering, Great Lakes, chlorine injection, sparker pressure pulses, Lake St. Clair, Chlorine, sparker control, chlorine alternative, sparker electrodes, sparker pressure pulse, zebra mussels, zebra mussel control

SBIR Phase II:

Nontoxic Sparker Control of Zebra Mussels