Use of powdered activated carbon to enhance methane production in sludge digestion

Conference · Sun Jan 01 04:00:00 EST 1978 · Biotechnol. Bioeng. Symp.; (United States)

OSTI ID:5747286

McConville, T; Maier, W J

Addition of small concentrations of powdered activated carbon to sewage sludges has been shown to have beneficial effects in anaerobic digestion. Gas production (65 to 60% methane) is increased by 10 to 15% at high detention time; large increases were observed at low detention times. Increased gas production is mirrored by increased conversion of volatile suspended solids. PAC addition also improves the dewatering characteristics of the digested sludges and reduces potential order problems. The latter benefits are particularly important in terms of facilitating the ultimate disposal of sludge solids. Dewatering characteristics improve with increasing PAC dosages whereas gas production is optimized at 150 mg/liter dosage rate. The benefits for PAC addition are magnified at lower detention times. Stable operations with 40% reduction in volatile suspended solids were obtained with 150 mg/liter PAC dosage at a 4-day detention time. The control digester without PAC addition was on the verge of washout as evidenced by lower gas production, lower pH, and poor dewaterability. Thus PAC addition could be used to increase the capacity of existing digesters or save capital on new designs. Analysis of the test data in terms of mathematical models indicates that the benefits associated with PAC addition may be the result of localized changes in bacterial-substrate-enzyme concentration. It is postulated that PAC addition leads to the formation of biochemically active sites that enhance the coupling of the sequential conversion of polymeric substances into soluble substrates, fatty acids, and finally into gas. The surface properties of the activated carbon should therefore be tailored to providing optimal conditions for the formation of biochemically active sites. 8 figures, 2 tables.

• Research Organization: Univ. of Minnesota, Minneapolis
• OSTI ID: 5747286
• Conference Information: Journal Name: Biotechnol. Bioeng. Symp.; (United States) Journal Volume: 8
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090122* -- Hydrocarbon Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
140504 -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320604 -- Energy Conservation
Consumption
& Utilization-- Municipalities & Community Systems-- Municipal Waste Management-- (1980-)
ACTIVATED CARBON
ADSORBENTS
ALKANES
ANAEROBIC DIGESTION
BIOCHEMISTRY
BIOCONVERSION
BIOSYNTHESIS
CARBON
CHEMISTRY
CRYOGENIC FLUIDS
DIGESTION
ELEMENTS
FLUIDS
HYDROCARBONS
MANAGEMENT
METHANE
NONMETALS
ORGANIC COMPOUNDS
PH VALUE
POWDERS
PROCESSING
REMOVAL
SEWAGE
SEWAGE SLUDGE
SYNTHESIS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
WATER REMOVAL