Microbial Analysis and Efficiency of Biofiltration Packing Systems for Hydrogen Sulfide Removal from Wastewater Off Gas

Abstract

Hydrogen sulfide (H2S) is commonly detected among waste gases from wastewater treatment plants causing atmospheric pollution, which affects human and environmental health. The aim of this study is to characterize the microbial diversity present within two different H2S biofiltration systems packed with either pozzolan or marble and to assess their efficiency for H2S removal. Few examples were reported about the relationship between the characteristics of the packing material and biofilter performance. Physicochemical parameters such as sulfate concentrations and pH are measured along this study. Sulfate concentrations produced by H2S oxidation were higher using marble biofilter and a higher efficiency of H2S removal was observed. Microbial diversity was characterized using a culture-independent 16S rRNA gene approach. Our results show that the biofilter packed with marble is very acidic (pH <3) and exhibits a higher bacterial diversity with three dominant bacterial families: Xanthomonadaceae, Hydrogenophilaceae, and Spirillaceae. However the biofilter packed with pozzolan is less acidic (pH 5.7–6.8) and shows completely different phylotypes where the plastid 16S rRNA gene of the red algae Cyanidium caldarium and Acidithiobacillus bacterium were retrieved. Such results show that the selection of an appropriate packing material is essential to the odor removal performance of a biofilter system and should allow for the design of better reactor with optimal operating conditions.