A comparison and evaluation of the effects of biochar on the anaerobic digestion of excess and anaerobic sludge

• Published in: The Science of the total environment 2020-09, Vol.736, p.139159-139159, Article 139159
• Main Authors: Yan, Puxiang, Zhao, Yubin, Zhang, Huan, Chen, Shanshuai, Zhu, Wanbin, Yuan, Xufeng, Cui, Zongjun
• Format: Article
• Language: English
• Subjects: Anaerobic sludge; Biochar; Excess sludge; Methanomicrobiales; Trichococcus
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.139159

The mechanisms and enhancing effects of different biochar loadings on the digesters receiving low and high excess (or anaerobic) sludge loadings were thoroughly examined in the present study. This was done to explore an efficient method for converting excess sludge to anaerobic sludge. Biochar had an obvious effect on the anaerobic digestion of excess sludge but not on the anaerobic sludge. When the amount of biochar added was equivalent to 100% of the sludge TS, the cumulative methane yields of anaerobic digestion inoculated with small and large amounts of excess sludge were respectively 30.2 and 1.7 times that of those without biochar. The number of methanogens in the digesters that received small and large inoculations of excess sludge with 100% biochar, were respectively 105.4% and 20.6% higher than those without biochar. The biochar enhanced the systems performance because it selectively enriched the Trichococcus and Methanomicrobiales tightly attach to it. This enhanced the synergy and overall activity of the system by promoting biofilm development. Ultimately, the integration of 100% biochar and excess sludge can be used as a substitute for anaerobic sludge as an inoculum by giving similar overall performance. Biochar enhanced excess sludge can be used as an attractive alternative to anaerobic sludge for anaerobic digestion. [Display omitted] •This study provided a novel method to cultivate excess sludge to anaerobic sludge.•100% biochar and excess sludge can substitute anaerobic sludge as inoculum.•Biochar selectively enriched Trichococcus and Methanomicrobiales in excess sludge.