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Anaerobic waste‐activated sludge digestion–a bioconversion mechanism and kinetic model
Author(s) -
Shimizu Tatsuo,
Kudo Kenzo,
Nasu Yoshikazu
Publication year - 1993
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260411111
Subject(s) - bioconversion , anaerobic digestion , activated sludge , lysis , chemistry , hydrolysis , raw material , methanogenesis , chromatography , waste management , wastewater , fermentation , biochemistry , methane , organic chemistry , engineering
The anaerobic bioconversion of raw and mechanically lysed waste‐activated sludge was kinetically investigated. The hydrolysis of the biopolymers, such as protein, which leaked out from the biological sludge with ultrasonic lysis, was a first‐order reaction in anaerobic digestion and the rate constant was much higher that the decay rate constant of the raw waste activated sludge. An anaerobic digestion model that is capable of evaluating the effect of the mechanical sludge lysis on digestive performance was developed. The present model includes four major biological processes–the release of intracellular matter with sludge lysis; hydrolysis of biopolymers to volatile acids; the degradation of various volatile acids to acetate; and the conversion of acetate and hydrogen to methane. Each process was assumed to follow first order kinetics. The model suggested that when the lysed waste‐activated sludge was fed, the overall digestive performance remarkably increased in the two‐phase system consisting of an acid forming process and a methanogenic process, which ensured the symbiotic growth of acetogenic and methanogenic bacteria. © 1993 Wiley & Sons, Inc.