Shift of microbial community in gas-phase biofilters with different inocula, inlet loads and nitrogen sources

Abstract Biofilter research has traditionally concentrated on process optimization, especially in gaseous VOCs biofilters. However, microbial communities that develop upon inocula changes is not well understood. In this study, three lab-scale biofilters treating gaseous toluene were operated for 66 days with different inocula under changes in inlet loads and nitrogen sources. Biofilters which were each inoculated with activated sludge, river sediment or microbial consortium, led to a vastly different inoculum initially but gradually deviated toward similar structures with the same dominant microorganisms, i.e. Proteobacteria, Actinobacteria (phylum level) and Rhodococcus (genus level). However, differences still existed with much higher abundance (4.32%) of Achromobacter in the microbial consortium system. Of three inoculum systems that were tested, the microbial consortium system showed less significant changes in both community structure (with fewer newly detected genera, but with similar metabolic rates) and performance upon condition shifts with 73% - 77% removal efficiency except for stage 2. Higher microbial diversity, better performance and metabolic activity were obtained in two other inoculum systems (activated sludge and river sediment system). Some special organisms were observed i.e. the intestinal microorganism. This study describes the microbial community changes under different operation conditions in biofilter. It offers a further understand of biofiltration.