This work investigated the application of Focused Pulsed pretreatment on the subsequent anaerobic digestion of a mixture of primary and waste activated sludge. We present results from laboratory, pilot, and full-scale applications of the technology. In all cases, Focused Pulsed treatment resulted in significant solubilization of COD and other components from the sludge; treatment was effective on a continuous basis at pilot and full scale. Focused Pulsed treatment achieved two major benefits: 1) Increased utilization of the treated material in downstream processes, resulting in a significant reduction in waste biosolids requiring disposal; and 2) Improved conversion of treated material to methane, increasing the potential net energy capture from the biosolids. On-going work is focused on quantifying these operating and economic benefits, as well as verifying an additional benefit from the significant reduction of fecal coliform counts following treatment.

The Sanitary District of Decatur, Illinois operates a wastewater treatment plant that utilizes an anaerobic sludge digestion process. The gas produced by the digestion process is collected and used to generate electricity at the plant in a cogeneration system. The cogeneration system's two engines have recently required an increased amount of maintenance and are approaching the end of their useful life. In considering replacement options, the District and Malcolm Pirnie, Inc. analyzed the quality and quantity of anaerobic digester gas, identified electricity cogeneration technology alternatives, and further evaluated two gas use technologies and their respective gas treatment requirements.

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