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The Anaerobic Biodegradability of Municipal Sludge and Fat, Oil, and Grease at Mesophilic Conditions
Author(s) -
Kabouris John C.,
Tezel Ulas,
Pavlostathis Spyros G.,
Engelmann Michael,
Todd Allen C.,
Gillette Robert A.
Publication year - 2008
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143007x220699
Subject(s) - mesophile , grease , volatile suspended solids , biodegradation , chemical oxygen demand , chemistry , anaerobic digestion , pulp and paper industry , methane , waste management , total dissolved solids , acetic acid , population , food science , environmental engineering , environmental science , sewage treatment , bacteria , organic chemistry , biology , genetics , demography , sociology , engineering
The anaerobic biodegradability of municipal primary and secondary sludge with increasing levels of partially dewatered fat, oil, and grease (FOG) was assessed using a mixed methanogenic culture at 35 °C. Under batch conditions with an acclimated and enriched microbial population, the sludge loading was 3 kg volatile solids/m 3 and the highest FOG loading tested was 1.5 kg volatile solids/m 3 , resulting in a methane yield of 245 mL methane/g sludge volatile solids added at 35 °C and 1010 mL methane/g FOG volatile solids added at 35 °C. Under semicontinuous feeding conditions, the sludge and sludge plus FOG loading tested were 3 and 3.75 kg volatile solids/m 3 ‐d, respectively. Within 23 days of operation, the volatile fatty acid concentrations were reduced below 200 mg chemical oxygen demand/L (187 mg/L as acetic acid). Enhancement of sludge digestion was observed in those reactors where codigestion of sludge and FOG took place, which was attributed to a higher level of microbial activity maintained in these reactors as a result of FOG degradation. The results of this study demonstrate that beneficial use of FOG through codigestion with municipal sludge is feasible.