Proceedings

This paper focuses on three representative thermophilic anaerobic digestion projects: a very large project at the Hyperion Treatment Plant in Los Angeles and a medium-sized project in Waterloo, Iowa – both of which have been successfully in operation for several years – as well as a small plant in Waupun, Wisconsin, which was just put into service this spring. All three are conversions of plants originally designed for mesophilic anaerobic digestion only. Discussed are why the process was chosen in each case (varying from getting more out of existing tankage to producing a class A biosolids); the economic, design, and operating features of each plant; and the operation of each plant through Summer 2004. Also covered is re-growth of pathogens, odours, dewatering, and operating and start-up pointers.

KEY WORDS Anaerobic digestion, biosolids, Class A, digester, mesophilic, odours, pathogens, regrowth, sludge, thermophilic