Airlift two-phase partitioning bioreactor for dichloromethane removal: Silicone rubber stimulated biodegradation and its auto-circulation

• Published in: Journal of environmental management 2022-10, Vol.319, p.115610-115610, Article 115610
• Main Authors: Liu, Hao-Yang, Yu, Yang, Yu, Ning-Ning, Ding, Yun-Feng, Chen, Jian-Meng, Chen, Dong-Zhi
• Format: Article
• Language: English
• Subjects: Airlift bioreactor; Cell surface hydrophobicity; Dichloromethane; Microbial community stability; Silicone rubber
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.115610

Solid non-aqueous phases (NAPs), such as silicone rubber, have been used extensively to improve the removal of volatile organic compounds (VOCs). However, the removal of VOCs is difficult to be further improved because the poor understanding of the mass transfer and reaction processes. Further, the conventional reactors were either complicated or uneconomical. In view of this, herein, an airlift bioreactor with silicone rubber was designed and investigated for dichloromethane (DCM) treatment. The removal efficiency of Reactor 1 (with silicone rubber) was significantly higher than that of Reactor 2 (without silicone rubber), with corresponding higher chloride ion and CO2 production. It was found that Reactor 1 achieved a much better DCM shock tolerance capability and biomass stability than Reactor 2. Silicone rubber not only enhanced the mass transfer in terms of both gas/liquid and gas/microbial phases, but also decreased the toxicity of DCM to microorganisms. Noteworthily, despite the identical inoculum used, the relative abundance of potential DCM-degrading bacteria in Reactor 1 (91.2%) was much higher than that in Reactor 2 (24.3%) at 216 h. Additionally, the silicone rubber could be automatically circulated in the airlift bioreactor due to the driven effect of the airflow, resulting in a significant reduction of energy consumption. [Display omitted] •Dichloromethane (DCM) shock tolerance capability was enhanced by silicone rubber.•Microbial activity was improved in presence of silicone rubber.•Gas/biological phases mass transfer of DCM was strengthened by silicone rubber.•Airlift bioreactor achieved automatically circulation and low energy consumption.•The stability of biomass and community structure both enhanced system reliability.