ABSTRACT
A major obstacle to the widespread acceptance of vermicomposting as a general organic-waste-management alternative is a lack of adequate scienti¤c information about the potential for human pathogen reduction during vermicomposting of sewage biosolids or even animal manures. In contrast to conventional composting, which is often de¤ned by the presence of a high temperature or thermophilic phase 50-70°C (122-158°F), vermicomposting is a mesophilic process. It requires that the substrate temperatures remain relatively low generally below 35°C (95°F), or else the earthworms may become inactive, ¯ee, or die, thereby disrupting the vermicomposting process. A major bene¤t of higher temperatures during conventional composting is its potential reduction or elimination of many human pathogens such as Salmonella and E. coli, human viruses, and helminths. Based on a signi¤cant volume of scienti¤c literature, U.S. Environmental Protection Agency (EPA) standards for the composting process have been developed that specify the duration and extent of raised temperatures necessary (above 55°C (161°F) for 72 hours) to eliminate the
CONTENTS
I Introduction ..................................................................................................249 II Laboratory Studies on Human Pathogen Reduction by
Vermicomposting..........................................................................................250 III Field Studies on Human Pathogen Reductions by Vermicomposting .......... 252 IV De¤nitive Study on Human Pathogen Reduction in Sewage Biosolids ........ 255 V Possible Mechanisms of Pathogen Reduction during Vermicomposting ..... 258 VI Conclusions ................................................................................................... 259 References ..............................................................................................................260
risk of human pathogen contamination in ¤nished composts so they can be used safely as Class A materials for land use (Environmental Protection Agency [EPA] 1999). These standards have been incorporated into U.S. state and EPA regulations for the production and use of composts.
