Anaerobic co-digestion of food waste and dairy manure: Effects of food waste particle size and organic loading rate

• Published in: Journal of environmental management 2014-01, Vol.133, p.268-274
• Main Authors: Agyeman, Fred O., Tao, Wendong
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Anaerobiosis; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Conservation, protection and management of environment and wildlife; Dairy manure; Dairying; Dewaterability; Effects; Food; Food waste; Fundamental and applied biological sciences. Psychology; General aspects; Manure; Manures; Mechanical pretreatment; Methane; Organic loading rate; Particle Size; Waste Management; Waste materials
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2013.12.016

This study was to comprehensively evaluate the effects of food waste particle size on co-digestion of food waste and dairy manure at organic loading rates increased stepwise from 0.67 to 3g/L/d of volatile solids (VS). Three anaerobic digesters were fed semi-continuously with equal VS amounts of food waste and dairy manure. Food waste was ground to 2.5mm (fine), 4mm (medium), and 8mm (coarse) for the three digesters, respectively. Methane production rate and specific methane yield were significantly higher in the digester with fine food waste. Digestate dewaterability was improved significantly by reducing food waste particle size. Specific methane yield was highest at the organic loading rate of 2g VS/L/d, being 0.63, 0.56, and 0.47LCH4/g VS with fine, medium, and coarse food waste, respectively. Methane production rate was highest (1.40–1.53LCH4/L/d) at the organic loading rate of 3gVS/L/d. The energy used to grind food waste was minor compared with the heating value of the methane produced. •Reducing food waste particle size from 8 to 2.5mm enhanced CH4 production.•Reducing food waste particle size significantly improved digestate dewaterability.•Energy used to grind food waste is minor compared to heating value of CH4 produced.•Specific methane yield was highest (0.47–0.63L/gVS) at 2gVS/L/d of loading.•Methane production was highest (1.40–1.53L/L/d) at loading rate of 3gVS/L/d.