Treatment of mixed waste-gas containing H2S, dichloromethane and tetrahydrofuran by a multi-layer biotrickling filter

Biotrickling filter could be used for the abatement of volatile inorganic compounds (VICs) and volatile organic compounds (VOCs) simultaneously, a multi-layer biotrickling filter (MLBTF) system was constructed to lift the contradiction of pH between VICs degrader and VOCs degrader. The pH levels of the bottom, middle, and top layers of the MLBTF were controlled at 4.5, 6.0, and 7.5, respectively. Biological removal of ternary mixed hydrogen sulfide (H2S), tetrahydrofuran (THF), and dichloromethane (DCM) was conducted for 120 days. The result indicated that H2S was mainly removed in the bottom layer, the THF and DCM were mainly removed in the middle layer. The removal efficiency of 200 mg/L H2S, 100 mg/L THF, and 100 mg/L DCM were all exceeded 95% with an empty bed residence time of 35 s. The maximum elimination capabilities of H2S, THF, and DCM were 52.5, 26.7, and 17.2 g/(m3·h) respectively. Results from polymerase chain reaction denaturing gradient gel electrophoresis revealed that the dominant microorganisms in the bottom layer of MLBTF were Methylosinus sp. and Acidithiobacillus sp. The Pseudomonas sp., Achromobacter sp., and Methylobacterium sp. remained dominant throughout the operation in the middle and top layers. These findings demonstrated that the proposed method can effectively enhance the performance of VICs and VOCs removal by controlling pH and microbial community in each layer of the MLBTF. It is believed that this work provides a new insight into the biological removal of VOCs by the MLBTF.