Significance of different mixing conditions on performance and microbial communities in anaerobic digester amended with granular and powdered activated carbon

• Published in: Bioresource technology Vol. 341; p. 125768
• Main Authors: Shekhar Bose, Raj, Chowdhury, Bappi, Zakaria, Basem S., Kumar Tiwari, Manoj, Ranjan Dhar, Bipro
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2021
• Subjects: Anaerobic digestion; Biomethane; Blackwater; Conductive materials; Mixing conditions; Blackwater; Biomethane; Conductive materials; Mixing conditions; Anaerobic digestion
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2021.125768

[Display omitted] •Impact of various mixing conditions was studied for GAC and PAC amended digesters.•GAC amended digester attained the highest methane production without any mixing.•Intermittent mixing in GAC and control resulted in comparable methane production.•Continuous mixing in GAC amended digester provided the lowest methane production.•Mixing affected the enrichment/retention of bacterial and archaeal populations. Conductive materials amendment in anaerobic digestion (AD) is a promising strategy for boosting the methanogenesis process. Despite mixing is a critical parameter, the behavior of digesters amended with conductive additives upon different mixing conditions has rarely been investigated. This study investigated continuous mixing, intermittent mixing (10 min in every 12 h), and non-mixing conditions for digesters amended with granular activated carbon (GAC) and powdered activated carbon (PAC). The non-mixed GAC digester provided the highest methane yield (318 ± 28 mL/g COD) from synthetic blackwater, while intermittently mixed GAC and control exhibited similar methane yields (290–294 mL/g COD). For non-mixed systems, microbial richness and diversity increased with GAC and PAC amendment. In contrast, continuous and intermittent mixing increased microbial diversity and richness in control reactors while reduced the same in GAC and PAC amended reactors. Overall, various mixing conditions distinctly changed the degree of enrichment/retention of microbes and consequently influenced methane recovery.