Assessing dairy manure pathogen indicator inactivation under anaerobic and aerobic digestions in mesophilic temperature

Abstract

Fate and transport of pathogens of animal waste from farm land to ambient water is a serious issue. Controlling pathogens in ambient water requires mitigating pathogen transport from crop land, receiving animal waste as fertilizers, to surface and ground water. Treating manure prior to land application utilizing efficient pathogen treatment processes is an option. Here we have assessed the efficacies of animal waste treatment processes (anaerobic and aerobic digestions) on inactivation of dairy waste K coli, a pathogen indicator, level. Anaerobic and aerobic digestions of animal waste were carried out in mesophilic temperature (37° C) under batch mode, and K coli inactivation in digestate was assessed. Results show that about 40 days of incubation was required in anaerobic condition for K coli reduction from seven orders of magnitude to two orders of magnitude, while in aerobic condition, K coli levels were reduced from seven to one order of magnitude in 12 days of incubation. In addition, we have assessed total solid (TS) and volatile solid (VS) reductions in anaerobic and aerobic conditions. In 41 days of incubation, TS in anaerobic condition was reduced to 86% of the initial TS, while in aerobic condition it was reduced to 79% of the initial TS. After 41 days of incubation, the VS in anaerobic and aerobic conditions were 79 and 66% of the initial VS. In aerobic condition, pH was increased by 32% at the end incubation, while in anaerobic condition pH was reduced by 12% We anticipate that the study presented here will be useful while assessing the anaerobic and aerobic reactor efficiencies on the inactivation of pathogen indicators in dairy manure.