Effect of solids retention time on the bioavailability of organic carbon in anaerobically digested swine waste

• Published in: Bioresource technology 2014-06, Vol.162, p.14-20
• Main Authors: Kinyua, Maureen N., Cunningham, Jeffrey, Ergas, Sarina J.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Anaerobic digestion; Anaerobiosis; Animal productions; Applied sciences; Bioavailability; Biodegradation, Environmental; Biological and medical sciences; Biological Availability; Biological Oxygen Demand Analysis; Biological treatment of sewage sludges and wastes; Bioreactors; Biotechnology; Carbon; Carbon - analysis; Centrate; Chemical Fractionation; Denitrification; Digesters; Effluents; Environment and pollution; Exact sciences and technology; Fatty Acids, Volatile - analysis; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Hydrolysis; Industrial applications and implications. Economical aspects; Methane; Methane production; Organic Chemicals - analysis; Pollution; Readily biodegradable COD; Refuse Disposal - methods; Respirometry; Swine; Time Factors; Use of agricultural and forest wastes. Biomass use, bioconversion; Waste Disposal, Fluid; Waste Products - analysis; Wastes
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2014.03.111

•Swine waste was treated in anaerobic digesters with varying SRT.•Digester centrate was used as an organic carbon source for denitrification.•Excellent volatile solids removal, CH4 yield and CH4 production rates were observed.•Digester centrate supported denitrification, with highest rates at a 21day SRT. Anaerobic digestion (AD) can be used to stabilize and produce energy from livestock waste; however, digester effluents may require further treatment to remove nitrogen. This paper quantifies the effects of varying solids retention time (SRT) methane yield, volatile solids (VS) reduction and organic carbon bioavailability for denitrification during swine waste AD. Four bench-scale anaerobic digesters, with SRTs of 14, 21, 28 and 42days, operated with swine waste feed. Effluent organic carbon bioavailability was measured using anoxic microcosms and respirometry. Excellent performance was observed for all four digesters, with >60% VS removal and CH4 yields between 0.1 and 0.3(m3CH4)/(kgVS added). Organic carbon in the centrate as an internal organic carbon source for denitrification supported maximum specific denitrification rates between 47 and 56(mgNO3−-N)/(gVSSh). The digester with the 21-day SRT had the highest CH4 yield and maximum specific denitrification rates.