Sequencing mesophilic and thermophilic anaerobic digesters. Final report
This project employed two laboratory bench scale, complete-mix anaerobic sludge digesters arranged in a series configuration. The first digester was operated at 35/sup 0/C (mesophilic) and the second at 50/sup 0/C (thermophilic). A portion of the thermophilic sludge was recycled through an aeration basin. As a comparison to the mesophilic-thermophilic sequencing, a mesophilic-mesophilic digester sequence, without sludge recycle to the aeration basin, was operated in parallel to the test units and loaded at an equivalent rate. Conclusions of this study are as follows: in establishing a thermophilic anaerobic digester, a slow-start procedure, in which the temperature is increased at a rate of 0.6/sup 0/C per day with loading, appears to produce a more stable thermophilic digester in a shorter period of time than a quick-start procedure, in which the temperature is increased rapidly with no loading. Even after a year, the slow-start thermophilic digester proved to be unstable once sequencing began. A greater volatile solids, COD, BOD, and grease reduction with a higher gas production was achieved using a mesophilic-mesophilic sequence, probably, in part, due to the instability (volatile acids in the effluent) of the thermophilic digester in the mesophilic-thermophilic sequence. A greater total kjeldahl N (TKN) and total coliform destruction was achieved in the thermophilic digester, however, poor dewatering characteristics, as indicated by the capillary suction time (CST), and an obnoxious odor were also evident. Other than an increase in effluent suspended solids, the recycle of thermophilic sludge to an aeration basin produced no discernable effect. 9 figs., 3 tabs.
- Research Organization:
- Atlanta Bureau of Pollution Control, GA (USA)
- DOE Contract Number:
- FG44-81R410433
- OSTI ID:
- 5722221
- Report Number(s):
- DOE/R4/10433-T1; ON: DE85012203
- Country of Publication:
- United States
- Language:
- English
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ALKANES
ANAEROBIC DIGESTION
BENCH-SCALE EXPERIMENTS
BIOCONVERSION
BIOREACTORS
DATA
DESIGN
DIGESTION
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
LIQUID WASTES
MANAGEMENT
MEDIUM TEMPERATURE
METHANE
NUMERICAL DATA
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PROCESSING
PRODUCTION
SLUDGES
TEMPERATURE EFFECTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTE WATER
WASTES
WATER
WATER TREATMENT