Cross-parameter influences of pH and heat for biosolids stabilization

Abstract

Biosolids stabilized by lime addition have high material costs and high transportation costs, and excessive ammonia volatilization. Decreasing the amount of lime added while still achieving stabilization would allow for more sustainable reuse of biosolids. This study examined the combined influence of pH and heat on fecal coliform destruction and ammonia loss in biosolids. Fecal coliform concentrations of less than 1000 MPN/g were achieved with pH as low as 10 combined with 1-hour incubation at 60 °C. Increased incubation temperatures were associated with decreased specific oxygen uptake rates, suggesting decreased readily-available carbon for microbial activity. Decreased lime additions resulted in reduced ammonia loss in the biosolids, suggesting an improved potential fertilizer benefit. The study demonstrated that optimizing combined lime and heat stabilization has the potential for increasing beneficial reuse and enhance environmental sustainability.