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

In this study, high concentration of HS (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 HS increased from 101.7 to 422.0 g/m/h, the removal efficiency of HS decreased from 100.0% to 91.4%, and the maximum elimination capacity (EC) was 386.0 ± 10.5 gHS/m/h when empty bed retention time (EBRT) was 1.0 min. The slightly alkaline condition could increase the mass transfer of HS from gas to liquid phase and avoid the toxic effect of high concentration of HS, resulting in high removal performance of HS in the system. With the increase of HS inlet loading, the ratio of SO in bio-desulfurization products gradually decreased, while that of S increased. At 101.7-210.7 gHS/m/h of inlet loading, SO was the dominant product with the ratio of above 50.00%, while S became the dominant product with 62.96% at 422.0 gHS/m/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 gHS/m/h of inlet loading, respectively. The SOB Sulfurimonas might play an important role for bio-desulfurization of high concentration of HS in a slightly alkaline BTF under high inlet loading of HS.