The performance and microbial community in a slightly alkaline biotrickling filter for the removal of high concentration H2S from biogas.

In this study, high concentration of H2S (i.e., 5000 ppmv) in biogas was effectively removed by a slightly alkaline biotricking filter (BTF) with Polypropylene rings as packing material and oxygen from air as the electron acceptor. The results showed that when the inlet loading of H2S increased from 101.7 to 422.0 g/m3/h, the removal efficiency of H2S decreased from 100.0% to 91.4%, and the maximum elimination capacity (EC) was 386.0 ± 10.5 gH2S/m3/h when empty bed retention time (EBRT) was 1.0 min. The slightly alkaline condition could increase the mass transfer of H2S from gas to liquid phase and avoid the toxic effect of high concentration of H2S, resulting in high removal performance of H2S in the system. With the increase of H2S inlet loading, the ratio of SO42- in bio-desulfurization products gradually decreased, while that of S0 increased. At 101.7-210.7 gH2S/m3/h of inlet loading, SO42- was the dominant product with the ratio of above 50.00%, while S0 became the dominant product with 62.96% at 422.0 gH2S/m3/h of inlet loading. The 16S rDNA sequencing results showed that the dominant genus in the BTF was sulfide-oxidizing bacteria (SOB), with the abundance of SOB decreased with the increase of inlet loading. The dominant genus were Pseudomonas, Halothiobacillus and Sulfurimonas in the BTF at 101.7, 139.8 and 210.7 gH2S/m3/h of inlet loading, respectively. The SOB Sulfurimonas might play an important role for bio-desulfurization of high concentration of H2S in a slightly alkaline BTF under high inlet loading of H2S.