Characterization of H2S removal and microbial community in landfill cover soils
2015
Xia, Fang-Fang | Zhang, Hong-Tao | Wei, Xiao-Meng | Su, Yao | He, Ruo
H₂S is a source of odors at landfills and poses a threat to the surrounding environment and public health. In this work, compared with a usual landfill cover soil (LCS), H₂S removal and biotransformation were characterized in waste biocover soil (WBS), an alternative landfill cover material. With the input of landfill gas (LFG), the gas concentrations of CH₄, CO₂, O₂, and H₂S, microbial community and activity in landfill covers changed with time. Compared with LCS, lower CH₄ and H₂S concentrations were detected in the WBS. The potential sulfur-oxidizing rate and sulfate-reducing rate as well as the contents of acid-volatile sulfide, SO₄ ²⁻, and total sulfur in the WBS and LCS were all increased with the input of LFG. After exposure to LFG for 35 days, the sulfur-oxidizing rate of the bottom layer of the WBS reached 82.5 μmol g dry weight (d.w.)⁻¹ day⁻¹, which was 4.3-5.4 times of that of LCS. H₂S-S was mainly deposited in the soil covers, while it escaped from landfills to the atmosphere. The adsorption, absorption, and biotransformation of H₂S could lead to the decrease in the pH values of landfill covers; especially, in the LCS with low pH buffer capacity, the pH value of the bottom layer dropped to below 4. Pyrosequencing of 16S ribosomal RNA (rRNA) gene showed that the known sulfur-metabolizing bacteria Ochrobactrum, Paracoccus, Comamonas, Pseudomonas, and Acinetobacter dominated in the WBS and LCS. Among them, Comamonas and Acinetobacter might play an important role in the metabolism of H₂S in the WBS. These findings are helpful to understand sulfur bioconversion process in landfill covers and to develop techniques for controlling odor pollution at landfills.
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