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Mesophilic Anaerobic Digestion with High‐Temperature Microwave Pretreatment and Importance of Inoculum Acclimation
Author(s) -
Toreci Isil,
Droste Ronald L.,
Kennedy Kevin J.
Publication year - 2011
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 - 10.2175/106143010x12780288628651
Subject(s) - mesophile , anaerobic digestion , acclimatization , digestion (alchemy) , chemistry , anaerobic exercise , food science , pulp and paper industry , microbiology and biotechnology , biology , bacteria , methane , botany , ecology , chromatography , engineering , genetics , physiology
Thickened waste activated sludge (TWAS) was pretreated with microwave irradiation to temperatures higher than the boiling point (between 110 and 175°C) using different microwave intensities. Biochemical methane potential (BMP) assays demonstrated that, although mesophilic anaerobic digestion (MAD) inoculum used was acclimated for 4 months with microwave pretreated TWAS (to 175°C), acute methanogenic inhibition was observed. Additionally, the microwave conditions applied increased the soluble chemical oxygen demand (sCOD)‐to‐total COD (tCOD) ratio; however, no significant enhancement in the rate or extent of TWAS stabilization was observed for the microwave‐pretreated samples. Microwave pretreatment to between 110 and 175°C at lower microwave intensity with a better acclimated MAD inoculum (acclimatized for an additional 3 months) resulted in minimal methanogenic inhibition (improved acclimation) and improved the rate and extent of TWAS biodegradation, as determined by volatile solids removal and biogas production (microwave applied at lower microwave intensity). The TWAS pretreated to 175°C produced 31 ± 6% more biogas than the control (raw TWAS) by the 18th day of the BMP test, whereas the highest improvement observed from the first set of BMP experiments was 13 ± 1%.