Characterisation and control of the biosolids storage environment: Implications for E. coli dynamics

• Published in: The Science of the total environment 2021-01, Vol.752, p.141705-141705, Article 141705
• Main Authors: Fane, S., Nocker, A., Vale, P., Casado, M. Rivas, Cartmell, E., Harris, J., Fernández, Y. Bajón, Tyrrel, S.
• Format: Article
• Language: English
• Subjects: Biosolids; E. coli; Log reduction; Pathogens; Sewage sludge; Temperature
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.141705

E. coli survival in biosolids storage may present a risk of non-compliance with guidelines designed to ensure a quality product safe for agricultural use. The storage environment may affect E. coli survival but presently, storage characteristics are not well profiled. Typically biosolids storage environments are not actively controlled or monitored to support increased product quality or improved microbial compliance. This two-phased study aimed to identify the environmental factors that control bacterial concentrations through a long term, controlled monitoring study (phase 1) and a field-scale demonstration trial modifying precursors to bacterial growth (phase 2). Digested and dewatered biosolids were stored in operational-scale stockpiles to elucidate factors controlling E. coli dynamics. E. coli concentrations, stockpile dry solids, temperature, redox and ambient weather data were monitored. Results from ANCOVA analysis showed statistically significant (p 25 °C for a 28 day period and achieved a 3.7 Log E. coli reduction. In winter months E. coli suppression was limited with concentrations >6 Log10 CFU g−1 DS maintained. The ANCOVA analysis has identified the significant role that physical environmental factors, such as stockpile temperature, has on E. coli dynamics and the opportunities for control. [Display omitted] •This study successfully profiled the biosolids storage environment.•Temperature is a significant factor affecting E. coli die-off in biosolids.•Storage modifications demonstrated control of temperature to suppress E. coli.•>25 °C achieved in covered trial showed an E. coli decline of 3.7 Log over 28 days.•Storage environment modifications can ensure microbial compliance is achieved.