Hygienization of sludge through anaerobic digestion at 35, 55 and 60 °C.

Legislation in Sweden and the European Union concerning the use of sewage sludge in agriculture is under revision and future concentration limits for pathogens in treated sludge are likely to be expected. The aim of this study was to evaluate the hygienization of Salmonella, Escherichia coli, Enterococcus and Clostridium perfringens through continuous anaerobic digestion at 35, 55 or 60 °C, as well as to investigate process stability and methane production at 60 °C. The results indicated that digestion at 55 or 60 °C with a minimum exposure time of 2 h resulted in good reduction of Salmonella, E. coli and Enterococcus and that anaerobic digestion could thus be used to reach the concentration limits suggested for the EU, as well as Sweden. Furthermore, stable continuous anaerobic digestion of sludge was achieved at 60 °C, albeit with 10% less methane production compared to digestion at 35 and 55 °C.

[1]  M. Danielsson-Tham,et al.  Bacterial pathogen incidences in sludge from Swedish sewage treatment plants. , 2004, Water research.

[2]  Jaai Kim,et al.  Group-specific primer and probe sets to detect methanogenic communities using quantitative real-time polymerase chain reaction. , 2005, Biotechnology and bioengineering.

[3]  P. Scherer,et al.  Continuous biogas production from fodder beet silage as sole substrate. , 2003, Water science and technology : a journal of the International Association on Water Pollution Research.

[4]  Willy Verstraete,et al.  Repeated pulse feeding induces functional stability in anaerobic digestion , 2013, Microbial biotechnology.

[5]  B. Inanc,et al.  Community Changes During Start-up in Methanogenic Bioreactors Exposed to Increasing Levels of Ammonia , 2005, Environmental technology.

[6]  E. Bagge,et al.  The effect of hygienic treatment on the microbial flora of biowaste at biogas plants. , 2005, Water research.

[7]  M. Ozaki,et al.  Inactivation of pathogenic bacteria under mesophilic and thermophilic conditions , 1997 .

[8]  B. Ahring,et al.  Effect of temperature increase from 55 to 65 degrees C on performance and microbial population dynamics of an anaerobic reactor treating cattle manure. , 2001, Water research.

[9]  Leena Sahlström,et al.  A review of survival of pathogenic bacteria in organic waste used in biogas plants. , 2003, Bioresource technology.

[10]  A. Nozhevnikova,et al.  Anaerobic manure treatment under extreme temperature conditions , 1999 .

[11]  Willy Verstraete,et al.  Methanosarcina: the rediscovered methanogen for heavy duty biomethanation. , 2012, Bioresource technology.

[12]  C Gruvberger,et al.  Digestion of sludge and organic waste in the sustainability concept for Malmö, Sweden. , 2004, Water science and technology : a journal of the International Association on Water Pollution Research.

[13]  M. Danielsson-Tham,et al.  A laboratory study of survival of selected microorganisms after heat treatment of biowaste used in biogas plants. , 2008, Bioresource technology.

[14]  John Elmerdahl Olsen,et al.  Bacterial decimation times in anaerobic digestions of animal slurries , 1987 .