Wastewater Treatment by Pulsed Electric Field Processing

Combined sewage outflows (CSOs) are a major contributor to water pollution in the United States. The impact of peak stormwater loads on sewage treatment plants leads to the discharge of significant amounts (1.26 billion gallons) of untreated sewage each year. The bacterial load represented by this discharge directly contributed to more than 2,200 beach closings in the year 2000, numerous closings of shellfish beds, and overall degradation of water quality in affected communities. Nationally, there are 9,471 CSOs across almost 800 communities. More than 200 of these communities are in significant population areas. Pulsed electric field (PEF) processing is a promising new technology that can treat CSOs for bacterial load without the serious drawbacks inherent in chlorination and ozonation. PEF processing kills microorganisms and spores by ¿electrocuting¿ them in the wastewater stream using high-voltage electrical pulses instead of heat or chemicals. PEF treatment can offer several orders of magnitude greater efficacy than is required for sewage/CSO discharge treatment. It is flexible enough to treat nominal sewage flows and handle the peak demands of stormwater overflow. It can easily handle turbulent, cloudy, and particulate-laden flows. PEF processing, developed primarily for liquid food processing and sterilization, is an ideal technology for investigation as a bacterial reduction approach for CSO/wastewater treatment. It is low cost, environmentally safe, and easily adaptable to multiple points in the wastewater treatment chain. It is very simple to install and operate in existing treatment plants. Although the use of PEF for wastewater treatment has been reported with very favorable results, its applicability to CSO treatment has never, to Diversified Technologies, Inc.¿s knowledge, been directly examined. Until recently, it was not possible to build PEF systems capable of handling commercial-scale, large-volume operations because no equipment existed that could generate electric pulses of sufficient power. However, solid-state systems built by Diversified Technologies, Inc., now make it possible to build a PEF system capable of processing the large volumes of wastewater handled by CSO facilities. Phase I of this research project will define PEF processing requirements, costs, and general efficacy for CSOs. Phase II will involve building a laboratory/pilot demonstration and solidifying marketing and partnership issues. Phase III will involve installation and operationalization of a full-scale PEF treatment facility.