Improving anaerobic digestion of easy-acidification substrates by promoting buffering capacity using biochar derived from vermicompost

• Published in: Bioresource technology 2017-03, Vol.227, p.286-296
• Main Authors: Wang, Dou, Ai, Jing, Shen, Fei, Yang, Gang, Zhang, Yanzong, Deng, Shihuai, Zhang, Jing, Zeng, Yongmei, Song, Chun
• Format: Article
• Language: English
• Subjects: Acid-buffering capacity; Anaerobic digestion; Anaerobiosis; Biochar; Biofuels; Buffers; Charcoal - chemistry; Chicken manure; Kitchen waste; Manure; Vermicompost
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2016.12.060

•KW & CM were anaerobically digested at high organic loading to form acidification.•VCBC and VC were employed as buffers to improve the anaerobic digestion of KW & CM.•VCBC exhibited better acid buffering capacity than VC.•CM can be well anaerobically digested with VC and VCBC addition.•KW digestion was not initialized with VC and VCBC, but it tended to be alleviated. Acid-buffering of VCBC and VC was evaluated using 4 VFAs, and their application on anaerobic digestion of CM and KW was investigated. Results indicated acid-buffering capacity of VCBC to acetic, propionic, butyric, and valeric acid was 2.5, 1.1, 1.9 and 1.6-fold higher comparing with VC. CM digestion was not initiated at higher organic loading of 50gTS/kg, while it worked well with 5.0% VCBC or VC. KW was not digested even though VC or VCBC was increased to 15% and 20%. However, KW digestion can be alleviated with increasing VCBC or VC proportion, in which the alleviation by VCBC was better than VC. Average VFAs concentration during CM digestion with VC was 4077.7mg/L comparing with 2835.8mg/L of VCBC, and biogas release was delayed for 10-days accompanying rapid pH decrease in CM digestion with VC, which reflected acid-buffering of biochar played a crucial role on improving anaerobic digestion.