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The History And Future Direction Of Wastewater Treatment Plant Residuals Disinfection And Energy Recovery Considerations
Citation:
SMITH JR, J. E. The History And Future Direction Of Wastewater Treatment Plant Residuals Disinfection And Energy Recovery Considerations. Presented at Graduate Student Seminar, Civil & Environmentally Engineering Department, University of Missouri, Columbia, MO, April 17, 2009.
Impact/Purpose:
To review the history of disinfection pratices for wastewater treatment plant residuals and discuss the development and limitations of the U.S. regulations.
Description:
Presentation will review the history of disinfection practices for wastewater treatment plant residuals and discuss both the development and limitations of the U.S. regulations. Present U.S. regulations protect human health by minimizing the contact of humans with infectious microorganisms. Processes like pasteurization reduce pathogens below their analytical detection limits, while processes like mesophilic anaerobic digestion strive to achieve the same goal with additional requirements for reducing organic matter and restricting crop harvesting and public access. Criteria employed in evaluating a new (innovative or alternative) disinfection process will be highlighted and processes recently evaluated and ones that are currently being evaluated described. It is important to understand how the stressors employed by a process contribute to its reduction of pathogenic bacteria, viruses, protozoa and parasites. For example with an alkaline disinfection process it is possible to utilize the beneficial effects of time, temperature, pH, chemical agents like ammonia, and pressure. Work underway to inventory facilities currently utilizing biogas from anaerobic digestion and speak with practitioners to learn: techniques for preparing residuals for digestion, methods to use for cleaning biogas (e.g. of siloxane), and how gas can be optimally utilized will be previewed. EPA is also talking with facilities treating or planning to treat residuals by gasification, combustion alone and with other waste materials, the SlurryCarb process, and a chemical or microbial fuel cell. It is estimated that the 16,583 municipal wastewater treatment facilities (WWTFs) in the USA use more than 1% of all electricity produced. Managing the residuals from these facilities is estimated to cost the nation as much as $10 billion annually. Only about 6% of the WWTFs or 1,066 treat more than 5 MGD and of these only 544 or a half have anaerobic digesters. Suprisingly, too, only 106 of these facilities bother to use the gas produced to provide heat or power. So the question arises, what can be done to change this situation?