Integrating electrocoagulation process with up-flow anaerobic sludge blanket for in-situ biomethanation and performance improvement

• Published in: Bioresource technology 2022-09, Vol.360, p.127536-127536, Article 127536
• Main Authors: Derakhshesh, Saeed, Abdollahzadeh Sharghi, Elham, Bonakdarpour, Babak, Khoshnevisan, Benyamin
• Format: Article
• Language: English
• Subjects: Acinetobacter; Anaerobic digestion; biogas; carbon dioxide; Carbon dioxide content; chemical oxygen demand; Electrocoagulation; Hydrogen; hydrogen production; methane; Methane production; Methanobacterium; Microbial community structure; phosphates; sludge; sulfates; turbidity; upflow anaerobic sludge blanket reactor
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2022.127536

[Display omitted] •An innovative anaerobic hybrid bioreactor was considered for in situ biomethanation.•Low CO2 content was achieved (below 2%) in EC-UASB within a short time.•Improvement in removal of pollutants and turbidity was achieved in EC-UASB.•No accumulation of volatile fatty acids was observed in EC-UASB.•Hydrogen and higher concentration of iron positively altered microbial community. In this study, the integration of the electrocoagulation (EC) process with anaerobic digestion as a novel in-situ biomethanation approach was considered for the first time. As a result of this integration (iron electrodes, current density of 1.5 mA/cm2 and an exposure mode of 10-min-ON/ 30-min-OFF), the carbon dioxide content of biogas reached below 2%. Also, the methane production rate improved by 18.0 ± 0.4%, whereas the removal efficiencies of chemical oxygen demand, turbidity, phosphate, and sulfate increased by 12.0 ± 1.5%, 30.7 ± 1.7%, > 99%, and 75.7%, respectively. Anaerobic granular sludge characteristics were also improved. Moreover, the EC process stimulated growth and quantity of functional microorganisms, especially Acinetobacter in bacterial and Methanobacterium in archaeal community. Methane concentration, however decreased due to possible excess hydrogen production. The application of the biogas as bio-hythane, and the optimization of the hybrid bioreactor to decrease hydrogen production, are possible avenues for further research.