Landfill CH₄ oxidation by mineralized refuse: Effects of NH₄ ⁺N incubation, water content and temperature
2012
Zhang, Yi | Zhang, Houhu | Jia, Bo | Wang, Wei | Zhu, Wei | Huang, Tianyin | Kong, Xiangji
Mineralized refuse, excavated from a municipal solid waste (MSW) landfill that had been closed for more than 10years, was incubated in livestock wastewater for 150d to accumulate ammonia-oxidizing bacteria and also co-oxidize methane (CH₄). The extent of CH₄ oxidation and carbon dioxide (CO₂) emissions from the incubated mineralized refuse (IMR) were investigated to assess its applicability as a bio-cover material at landfill sites for minimizing total greenhouse gas emission equivalents. From the initial 200mg nitrogen (N) kg⁻¹ incubated for 120h, the nitrate-N content produced in the IMR was twice (P<0.05) that of the untreated original mineralized refuse (OMR) and 3.81 (P<0.05) times that of soil. For an initial CH₄ concentration of approximately 10% by volume in the headspace, CH₄ consumption and net emission of CO₂ from the soil, IMR and OMR all agreed well with first-order and zero-order kinetics models for a 120-h incubation (R²=0.667 and R²=0.995, respectively). Similar to N turnover, the rate of consumption of CH₄ by the mineralized refuse was some 50.0% higher than for soil (P<0.05). Based on the net rate of CO₂ generation, the CH₄ oxidation rate by IMR was 14.2% (P>0.05) greater than for OMR and 56.1% (P>0.05) higher than for soil. Variation of water content and temperature produced substantially higher CH₄ consumption rates by IMR than by either OMR or soil. After treatment by livestock wastewater, the CH₄ oxidation capacity of mineralized refuse was moderately improved, due to the enhancement of CH₄ adsorption by retained suspended solids and the subsequent co-oxidation by the accumulated ammonia-oxidizing bacteria. By correlation analysis for the three experimental materials, CH₄ oxidation rate was significantly correlated with specific surface area and organic matter content (P<0.05), and was positively correlated with CO₂ generation, NH₄ ⁺N nitrification and NO₃ –N generation rate (P>0.05).
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