Pathogen and Indicator Organism Inactivation and Quantification for Low-Cost Low-Tech Biosolids Treatment

Biosolids are a by-product of municipal wastewater treatment which, when treated to reduce pathogens, can be land applied as a fertilizer. Class A biosolids must contain low pathogen levels and are unrestricted in their use. This thesis describes methods to identify pathogen and indicator organism (PIO) inactivation mechanisms and PIO inactivation rates for use in low-cost low-tech Class A processes. Procedures to control the levels of spiked bacteria and viruses, total solids, volatile fatty acids, pH, and temperature in biosolids are described for their use in laboratory experiments. Methods for coliphage in biosolids as a surrogate for total enteric viruses are also presented. The two-step enrichment method yields a most probable number estimate of coliphages and was found to have minimal interference from solids, limit background bacteria interference, and may be a useful process monitoring tool at wastewater treatment facilities