Co-digestion of source segregated domestic food waste to improve process stability

• Published in: Bioresource technology 2012-06, Vol.114, p.168-178
• Main Authors: Zhang, Yue, Banks, Charles J., Heaven, Sonia
• Format: Article
• Language: English
• Subjects: Ammonia; Animals; Biodegradation, Environmental; Bioreactors - microbiology; Card packaging; Cattle; Cattle slurry; Food Microbiology; Food waste; Industrial Waste - prevention & control; Refuse Disposal - methods; Sewage - microbiology; Specific methane production
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2012.03.040

► Cattle slurry and card packaging both improved food waste digestion stability. ► Food waste co-digestion with cattle slurry offers major environmental benefits. ► Higher loadings and energy yields achievable by co-digestion. ► Agricultural value of digestate was enhanced. ► Both co-substrates could recover a failing inoculum. Cattle slurry and card packaging were used to improve the operational stability of food waste digestion, with the aim of reducing digestate total ammoniacal nitrogen concentrations compared to food waste only. Use of cattle slurry could have major environmental benefits through reducing greenhouse gas emissions associated with current management practices; whilst card packaging is closely linked to food waste and could be co-collected as a source segregated material. Both options increase the renewable energy potential whilst retaining organic matter and nutrients for soil replenishment. Co-digestion allowed higher organic loadings and gave a more stable process. A high ammonia inoculum acclimated more readily to cattle slurry than card packaging, probably through supplementation by trace elements and micro-organisms. Long-term operation at a 75-litre scale showed a characteristic pattern of volatile fatty acid accumulation in mono-digestion of food waste, and allowed performance parameters to be determined for the co-digestion substrates.