H₂S Biotransformation Behavior During Liquid And Gas Manipulation In Landfill

Odor emission from landfill site arisen by H2S has seriously endangered human health and ecology safety. However, the current end control technologies for H2S from landfill are always passive due to the insufficient knowledge of H2S transformation process. This research studied the generation and emission behavior of H2S and the corresponding biotransformation process by sulfur-metabolizing microorganism using simulated landfills with different liquid and gas manipulation. It aims to provide some reference value for the active control of H2S from landfill.Firstly, the dynamic tracing research of simulated landfill showed that the behaviors of redox, migration and transformation of H2S precursors like sulfur-containing organic substrates and/or inorganic substrates significantly differed with landfills with different liquid and gas manipulation, which ultimately affected the H2S emission behaviors from the cover layer. By contrast, semi-aerobic mode improved the emission behavior of H2S more obviously than leachate recirculation. The introduction of oxygen and leachate recirculation theoretically promoted 100% of sulfate reduction, resulting in the significant accumulation of sulfide but without improvement of H2S emission potential.Secondly, the study of microbial diversity in landfill with key time point indicated that environmental factors had obvious effects on sulfur-metabolizing bacterial composition, and the effect of nitrate on the transformation of sulfur should not be ignored. The oxygen exposure obviously promoted the relatively abundance of the sulfate-reducing bacteria (SRB) like Desulfobulbus nearly 30 times but attenuated that of the nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) like Pseudomonas to one-tenth comparied with the anaerobic condition. The enhancement of sulfate reducing behavior and the corresponding attenuation of its metabolite controlled the final H2S emission.Finally, the batch investigation on typical sulfur-metabolizing microorganism suggested that NR-SOB like Thauera sp. and Paracoccus sp. in the mineralized refuse could completely oxidize sulfide to sulfate in the presence of nitrate, and simultaneously reduce nitrate to N2. It can lower the risk of the biotransformation from the accumulated sulfide into H2S inside of the landfill. However, the engineering potential of that NR-SOB needs further research.