Study On Aerobic Sulfate Reduction Behavior And Mechanism In Landfill

Landfill is the main municipal solid waste disposal method in China.However,the H2S odor problem arisen from landfill has become the main obstacle of sustainable construction of landfills and merits sustained attention.Based on the landfill aerobic sulfate reduction phenomenon previously discovered,this study explored the landfill aerobic sulfate reduction behavior and mechanism by focusing on the landfill gas-liquid-solid interaction interface,namely the active microbial metabolism zone.Firstly,the characterization of real large-scale landfills showed that landfilled refuse with different deposit ages from different landfills could provide excellent metabolic environment for sulfate-reducing bacteria(SRB),the functional microorganism of H2S yield.The powerful sulfate reduction trace could be observed in each landfilled refuse.Functional genes such as aprB and dsrA significantly mediated the distribution of sulfur-containing substrates and the corresponding metabolism products.Secondly,the typical gas-liquid-solid interaction interface was constructed.It was found that the interaction interface with moderate humidity and O2 concentration was the active zone for H2S production and emission of the landfill.The aerobic sulfate reduction process at the interactive interface still used SO42-as the main electron acceptor.However,trace O2 concentration indirectly participated in the sulfate reduction process at the interactive interface by promoting the conversion of intermediate-valent sulfur compounds to SO42-and acting as the electron acceptor.Finally,the interactive interface with periodic oxygen exposure was simulated.It was further found that the aerobic sulfate reduction process was sustainable and showed an increasing trend under the scenarios with limited electron donor or acceptor.The observed highest H2S concentration was 659.47 mg·m-3.Micro-aerobic condition promoted the sulfur cycle at the interactive interface and correspondingly maintained the sulfate reduction process.The high abundance of functional gene(dsrA and dsrB)expression and the microbial diversity characteristics indicated that the aerobic sulfate reduction was not a traditional SRB-dominated metabolic model,This study can provide important support for precise control of the H2S odor pollution in landfill from source.