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Acetoclastic methanogenic activity measurement by a titration bioassay
Author(s) -
Rozzi Alberto,
Castellazzi Luca,
Speece Richard E.
Publication year - 2001
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.10088
Subject(s) - titration , chemistry , methanogenesis , bioassay , anaerobic exercise , chloroform , acetic acid , chromatography , biomass (ecology) , bioreactor , substrate (aquarium) , environmental chemistry , methane , inorganic chemistry , organic chemistry , biology , ecology , physiology
A titration bioassay, designed to accurately determine the activity of acetoclastic methanogens, is described that also allows evaluation of inhibition due to potential toxicants on the active biomass. The instrument is made of a pH‐stat connected to an anaerobic batch reactor. Acetate is blended and mixed with anaerobic sludge in the reactor where a 1:1 N 2 and CO 2 mixture is sparged at the beginning of each test. As the acetoclastic methanogens consume acetate, the pH increase, and the titration unit adds acetic acid and keeps the pH constant. The rate of titrant addition is directly proportional to the methanogenic activity. A very useful feature of the system is its potential to operate for long periods (days) at constant pH and substrate (acetate) concentration. The theoretical background and principle of operation are described as well as some of the practical problems encountered with the use of the instrument. Estimation of kinetic constants for an anaerobic culture according to the Michaelis–Menten model is presented. Examples of inhibition by inorganics (NaCl) and chlorinated solvents (chloroform) are also given. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 20–26, 2002.