Anaerobic co-digestion of kitchen waste and pig manure with different mixing ratios

• Published in: Journal of bioscience and bioengineering Vol. 120; no. 1; pp. 51 - 57
• Main Authors: Tian, Hailin, Duan, Na, Lin, Cong, Li, Xue, Zhong, Mingzhu
• Format: Journal Article
• Language: English
• Published: Japan Elsevier B.V 01-07-2015
• Subjects: Anaerobic digestion; Anaerobiosis; Animals; Biodegradation, Environmental; Butyric Acid - metabolism; Co-digestion; Cooking; Different ratios; Fatty Acids, Volatile - chemistry; Fatty Acids, Volatile - metabolism; Kitchen waste; Manure; Methane - metabolism; Pig manure; Propionates - metabolism; Sus scrofa; Time Factors; Waste Products; Kitchen waste; Pig manure; Different ratios; Anaerobic digestion; Co-digestion
• ISSN: 1389-1723; 1347-4421
• DOI: 10.1016/j.jbiosc.2014.11.017

Anaerobic co-digestion of kitchen waste (KW) and pig manure (PM) with seven different PM to KW total solids (TS) ratios of 1:0, 5:1, 3:1, 1:1, 1:3, 1:5 and 0:1 was conducted at mesophilic temperature (35 ± 1°C) to investigate the feasibility and process performance. The co-digestion of PM and KW was found to be an available way to enhance methane production compared with solo-digestion of PM or KW. The ratio of PM to KW of 1:1 got the highest biodegradability (BDA) of 85.03% and a methane yield of 409.5 mL/gVS. For the co-digestion of KW and PM, there was no obvious inhibition of ammonia nitrogen because it was in an acceptable range from 1380 mg/L to 2020 mg/L in the whole process. However, severe methane inhibition and long lag phase due to the accumulation of volatile fatty acids (VFAs) was observed while the KW content was over 50%, and in the lag phase, propionic acid and butyric acid made up the major constituents of the total VFAs. The technical digestion time (T80: the time it takes to produce 80% of the digester's maximum gas production) of the above 7 ratios was 15, 21, 22, 27, 49, 62 and 61 days, respectively. In this study, a mixing ratio of 1:1 for PM and KW was found to maximize BDA and methane yield, provided a short digestion time and stable digestion performance and was therefore recommended for further study and engineering application.