Processing anaerobic sludge for extended storage as anaerobic digester inoculum
2014
Li, Jiajia | Zicari, Steven M. | Cui, Zongjun | Zhang, Ruihong
Thermophilic anaerobic sludge was processed to reduce the volume and moisture content in order to reduce costs for storing and transporting the sludge as microbial inoculum for anaerobic digester startup. The moisture content of the sludge was reduced from 98.7% to 82.0% via centrifugation and further to 71.5% via vacuum evaporation. The processed sludge was stored for 2 and 4months and compared with the fresh sludge for the biogas and methane production using food waste and non-fat dry milk as substrates. It was found that fresh unprocessed sludge had the highest methane yield and the yields of both unprocessed and processed sludges decreased during storage by 1–34%, however processed sludges seemed to regain some activity after 4months of storage as compared to samples stored for only 2months. Maximum methane production rates obtained from modified Gompertz model application also increased between the 2-month and 4-month processed samples.
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