Abstract
H2S emissions from landfill sites resulting from sulfate reduction has become a serious human health and ecological safety issue. This study investigated H2S emission behavior and sulfate metabolism occurring in simulated landfills under different operating conditions. Under aerobic conditions, great attenuation of the original sulfate content (from around 6000 mg kg−1 dropped to below 800 mg kg−1) with corresponding accumulation of sulfides and elemental sulfur were observed, indicating that sulfate reduction processes were intense under such conditions. Analysis of the bacterial community in these landfills showed great abundance (1.10%) and diversity of sulfur reducing types, confirming their active involvement in this process. In particular, the total abundance of sulfate-reducing bacteria increased nearly 30 times under aerobic conditions, leading to the transformation of sulfate to sulfide and other reduced sulfur species. Although exposure to air promoted the accumulation of sulfide, it did not lead to an increase in H2S release in these landfills.
Highlights
Air was investigated in laboratory batch test experiments[13]
The results showed that large amounts of H2S can be released from aged refuse, when it is re-excavated and exposed to air, especially within the first few hours
Two experiments involved anaerobic landfills being switched to semi-aerobic mode after day 175, using direct discharge (ASL) and leachate recirculation (RASL); while the other two experiments were run as semi-aerobic landfill (SL) and semi-aerobic landfill with leachate recirculation (RSL)
Summary
Air was investigated in laboratory batch test experiments[13]. The results showed that large amounts of H2S can be released from aged refuse, when it is re-excavated and exposed to air, especially within the first few hours. It was hypothesized that this involved aerobic sulfate reduction. The experimental scale was enlarged from a laboratory microcosm to simulated landfill reactor to determine the processes involved in this conversion of sulfur compounds. It aimed to identify aerobic sulfate reduction processes occurring in such landfills
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