Effects Of Leachate Incubation On Landfill CH₄Oxidation By Ammonia-oxidizing Bacteria In Mineralized Refuse

It is discussed in this paper that reduction of green house gas emission from refuselandfill site can be achieved by way of enrichment of ammonia oxidizing bacteria in themineralized refuse using NH4+-N from the The waste leachate and its oxidation on CH4.Via field survey and experimental simulation, the basic property and microstructure of thewaste leachate and mineralized refuse were studied and empHasis was placed on how toutilize leachate to domesticate mineralized refuse and the factors influencing the process inwhich mineralized refuse oxidizes CH₄. The main results are as follows.1. Mineralized refuse, with high infiltration rate, high hydraulic loading and thecapacity for water holding and transporting resembling soil, becomes a kind ofmicroorganism and multipHase porous.compound living organism with diversifiedmicroorganisms after long-term landfill. Particles of mineralized refuse vary inmicromorpHology, the majority of which are irregular polyhedral globe. The surface of theparticles is uneven layer structure, providing a larege specific surface area. In addition, thespace between particles are relatively large, which is good for existence of naturalventilation reoxygenation and aerobic micropolis. Heavy metal can be significantlyremoved from leachate by the combining use of resin and mineralized refuse, both ofwhich have large specific surface area. Most of the heavey metal are absorbed by resin, andthen the remaining can be removed by mineralized refuse.2. Mineralized refuse has a considerable capacity for nitrating NH₄⁺-N in the leachate,with a removal rate higher than60%after120days. In the experiment with200mg kg-1NH4+-N added, NO3--N content produced from the120-d incubated mineralized refuse was2.0-time and3.8-time more than those of the original mineralized refuse and clay soil.3. The optimum temperature of mineralized refuse to oxidize CH4lies between20and35C. Lower or higher temperature, especially the latter, are both to the disadvantage of oxidation.4. The optimum moisture content of mineralized refuse for the oxidation processis located in the interval between20%and30%.·5. Over-acidified or over alkalified （pH<4or pH>9） environment is bad for theoxidization, and the optimum lies between5.5and7.5. According to the data of the study,slightly acid soil environment, comparing with slightly alkaline one, works better for theammonia oxidizing bacteria in the mineralized refuse and thus works better for the CH4oxidation.6. Excessively small particle diameter leads to excessively low porosity, blocking the access CH4of and oxygen, and in turn leads to disadvantage of the oxidation. With aparticle diameter larger than2mm, CH₄can be significantly removed byammonia-oxidizing bacteria.7. The initial CH₄concentration is positively related to the CH4oxidation byammonia-oxidizing bacteria. The higher the initial CH₄concentration, the greater theoxidizing capacity of ammonia-oxidizing bacteria.8. The contaminant in the waste leachate exerts significant toxic effect on ammoniaoxidizing bacteria.