Bioaerosol emissions of pilot-scale low-pH and neutral-pH biofilters treating odors from landfill leachate: Characteristics and impact factors

Large amounts of bioaerosols are generated during the treatment of landfill leachate, which poses potential threat to public health safety. In this study, the concentrations, particle size distribution, and microbial community of bioaerosols emitted from the low-pH biofilter (LPB) and neutral-pH biofilter (NPB) used to treat the odors from landfill leachate, as well as the effect of the inlet flow rate (IFR) and water-containing rate (WCR) were investigated. The results showed that the removal efficiency of the LPB for heterotrophic bacteria and the NPB for fungi were higher when the IFR was higher. The outlet concentrations (OCs) of heterotrophic bacteria, neutral sulfur bacteria, ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, NO2, and NO3 were negatively correlated with the IFR in the LPB, whereas those of fungi and acidophilic sulfur bacteria were positively correlated with the IFR. Inverse correlation between the OCs and IFR was exhibited in the NPB. The proportions of dominant microorganisms with large particle size (> 3.3 mu m) reduced significantly after both the LPB and NPB, which was aggravated under higher WCR. The analysis of microbial community illustrated that the dominant heterotrophic bacteria were different, while the dominant fungi were similar in the bioaerosols between the LPB and NPB, respectively. Due to the different emission characteristics, bioaerosols in the LPB and NPB outlet should be distinguished and taken seriously. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study found that LPB and NPB showed better removal efficiency for different bacteria and fungi when the IFR was higher. The proportion of dominant microorganisms with large particle size in the bioaerosols significantly reduced after LPB and NPB, especially under higher WCR.