The effect of temperature on slaughterhouse wastewater treatment in anaerobic sequencing batch reactors.
High strength slaughterhouse wastewater was treated in four 42 l anaerobic sequencing batch reactors (ASBRs) operated at 30 degrees C, 25 degrees C and 20 degrees C. The wastewater contained between 30% and 53% of its chemical oxygen demand (COD) as suspended solids (SS). The ASBRs could easily support volumetric organic loading rates (OLRs) of 4.93, 2.94 and 2.75 kg/m3/d (biomass OLRs of 0.44, 0.42 and 0.14 g/g volatile SS (VSS)/d) at 30 degrees C, 25 degrees C, and 20 degrees C, respectively. At all operating temperatures, the total COD (TCOD) and soluble COD (SCOD) were reduced by over 92%, while average SS removal varied between 80% and 96%. Over the experimental period, 90.8%, 88.7% and 84.2% of the COD removed was transformed into methane at 30 degrees C, 25 degrees C and 20 degrees C, respectively. The decrease in the conversion of the COD removed into methane as operating temperature was lowered, may be partly explained by a lower degradation of influent SS as temperature was reduced. The reactors showed a high average methanogenic activity of 0.37, 0.34 and 0.12 g CH4-COD/gVSS/d (22.4, 12.7 and 11.8 l/d) at 30 degrees C, 25 degrees C and 20 degrees C, respectively. The average methane content in the biogas increased from 74.7% to 78.2% as temperature was lowered from 30 degrees C to 20 degrees C.
Massé
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Dairy and Swine Research and Dev Ctr, Agriculture and Agri-food Canada, 2000 Route 108 East, P.O. Box 90, Lennoxville, QC, Canada J1M 1Z3. massed@em.agr.ca
Masse
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D000003:Abattoirs; D000693:Anaerobiosis; D000818:Animals; D001673:Biodegradation, Environmental; D019149:Bioreactors; D001709:Biotechnology; D004867:Equipment Design; D019605:Euryarchaeota / Q000378:metabolism; D005740:Gases; D012722:Sewage; D013552:Swine; D013696:Temperature; D014865:Waste Disposal, Fluid
D005740:Gases; D012722:Sewage