Digestion of waste activated sludge by anaerobic rotating biological contactors
Two parallel, four-stage anaerobic rotating biological contactors (RBC) were continuously operated to evaluate the engineering feasibility of such an attached growth system for digesting sewage sludge. Waste activated sludge was used as the feed which contained 10,000 mg/l of suspended solids and an average total COD of 11,890 mg/l. The effects of three different hydraulic retention times (HRTs: 10, 5, 2.5 days) and three different operating temperatures (35, 30, 25 C) on the digester performance were evaluated. In addition, the maximum methanogenic capability of the RBC system in utilizing acetic, propionic and butyric acids was also assessed. Results indicated that the performance of the anaerobic RBS digester was strongly affected by both the HRT and the operating temperature. A decrease of either HRT or operating temperature would result in a lower stabilization efficiency. At 35 C the digester could stabilize 39.3% of the total sludge COD with a 5-day HRT, and this efficiency was very close to the minimum requirement of 40% in the general engineering practice. The accelerated digestion rate in an RBC system was mainly due to the high methanogenic capability existing in the attached-growths, which also avoid biological washout at a short hydraulic retention condition. Applications of the experimental data to an actual engineering design were also illustrated.
- Research Organization:
- Missouri Univ., Rolla, MO (United States)
- OSTI ID:
- 6089755
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
090900* -- Biomass Fuels-- Processing-- (1990-)
ACETIC ACID
ACTIVATED SLUDGE PROCESS
ALKANES
ANAEROBIC DIGESTION
BACTERIA
BIOCONVERSION
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BIOREACTORS
BUTYRIC ACID
CARBOXYLIC ACIDS
CHEMICAL OXYGEN DEMAND
CONTINUOUS CULTURE
DIGESTION
FEASIBILITY STUDIES
HYDROCARBONS
MANAGEMENT
MATERIALS
METHANE
METHANOGENIC BACTERIA
MICROORGANISMS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PERFORMANCE TESTING
PROCESSING
PROPIONIC ACID
SEWAGE
SEWAGE SLUDGE
SLUDGES
SYNTHESIS
TEMPERATURE DEPENDENCE
TESTING
TIME DEPENDENCE
WASTE MANAGEMENT
WASTE PROCESSING
WASTES