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Schoenbach, K.H., A. Abou-Ghazala, R.W. Alden, R. Turner, T. Fox, 1997. Biofouling Prevention With Pulsed Electric Fields, Old Dominion University, Center for Advanced ship Repair and Maintenance Abstract from The Seventh International Zebra Mussel and Other Aquatic Nuisance Species
Conference, New Orleans, Louisiana, January 1997
The application of pulsed electric fields to water containing micro- or macro-organisms has been proven to be a means of controlling the population of these organism, or to stun them over a certain electric field dependent time interval. The fact that the efficiency of this control mechanism increases with decreasing pulse duration opens the possibility to utilize microsecond pulse power technology for biofouling prevention in cooling water systems. The advantages over other techniques used for biofouling prevention such as its independence from chemicals, the fact that it is possible to stun, rather than kill unwanted biofouling species, that it does not generate shock waves which could affect the structure of the cooling system, and that it can be installed like a filter in front of an existing cooling system, without requiring any changes in the cooling system, make the pulsed electric field technology (PEFT) a strong contender to existing biofouling prevention methods. A recent field study, where tidal water from the Elizabeth River in Norfolk, VA, was treated by means of the pulsed electric field method, demonstrated complete prevention of biofouling in pipes when the river water at the intake of the pipes was exposed to electric field of 6.5 kV/cm with 770 nanosecond pulse duration. The efficiency was 1,400 gallons of treated water per kWh, an increase in efficiency by more than a factor of three compared to results presented at the 1996 Zebra Mussel Conference. Experiments with even lower electric fields and correspondingly lower energy consumption are under way. modeling results indicate that efficiencies of more than 50,00 gallons/ kWh may be reached in fresh water cooling systems. Contact: K.H. Schoenbach, Physical Electronics Research Institute, Old
Dominion University, 231 Kaufman Hall, Norfolk, VA 23529 or schoenb@rolls-royce.eng.odu.edu |