Microbial activity measurements for anaerobic sludge digestion
The use of particulate substrate in the anaerobic sludge digestion process makes it difficult to measure the biomass in these reactors. Adenosine triphosphate (ATP) and dehydrogenase activity (DHA) were investigated as indicators of the sludge activity for the anaerobic sludge digestion process. ATP measures the energy pools in the biomass and is therefore a measure of the total sludge activity. DHA measurement relies on the addition of specific substrates to stimulate the metabolic activity of the bacteria. Glucose, starch, propionic acid, butyric acid, acetic acid, and digester feed as added substrates were used to stimulate the metabolic activity for DHA measurements. Laboratory experiments were performed to monitor the microbial activity of anaerobic sludge digesters operated both under steady state and in batch mode. The ATP content responded rapidly to changes in the digester operation, which may be the result of increased non-growth associated biochemical activity, not that of increased numbers of the bacteria. DHA was more sensitive than ATP at both low and high sludge ages and seemed to be correlated with the cell's growth phase. At low sludge ages (less than 10 days) glucose as added substrate showed the highest DHA responses, while the digester food and no added substrated showed the highest response when the sludge age exceeded 20 days. A kinetic model based on the solids balances was developed to determine the microbial mass and activity. Both ATP and DHA on a VSS basis (viability) appeared nearly constant over a wide range of sludge ages for the kinetic model data, indicating that ATP and DHA may be used as a rapid and convenient indicator of microbial mass and activity for anaerobic sludge digestion.
- Research Organization:
- California Univ., Los Angeles (USA)
- OSTI ID:
- 6073776
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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