Characteristics Of The Methane Oxidation Coupled To Denitrification In The Aged Refuse And The Landfill Cover Soil

Landfill gas and leachate are the main secondary pollution from landfill. Especially, themethane from landfill gas and nitrogen from leachate are extremely concerned. At present,biotechnology is the most economical and effective engineering measures for the control ofCH₄emissions. The work investigated the characteristics of methane oxidation coupled todenitrification （AME-D） in the aged refuse and landfill cover soil. Firstly, the batch assays wereperformed to investigate the effects of different factors such as CH₄, O₂and NO₃^--N withdifferent concentrations on AME-D and thus the optimal reaction condition was obtained bydetermining the gas contents in the samples. Afterwars, the effects of moisture content, particlesize and Cu²⁺concentration on AME-D were observed in the optimal condition, also the thereaction kinetics was done. Finally, the mechanisms AME-D happened in aged refuse andlandfill cover soil were preliminarily explored by means of isotope tracer and biolog test. Themain results are as follows:（1） The concentrations of CH₄, O₂and NO₃^--N have significant influences on the oxidation ofCH₄（P <0.01） both in the aged refuse and landfill cover soil, and follow the orders ofCH₄>O₂>NO₃^--N. In the aged refuse, when the concentrations of CH₄and O₂arerespectively10%and20%, the oxidation efficiency of CH₄reach to97.77%, the production ofN₂is more than11.5%and N₂O is less than0.2%. While in the landfill cover soil, when theconcentrationgs of CH₄and O₂both are20%, those of CH₄, N₂and N₂O are repectively78.5%,more than11.3%and below detection.（2） The most appropriate moisture content for AME-D in the aged refuse and landfill coversoil are respectively33.3%and15.3%, the optimal particle size are both below0.9mm. In theaged refuse,when Cu²⁺concentrations range from50to100mg.kg^-1or400to600mg.kg^-1,though the production of N₂decreased with the increase of Cu²⁺, the removal of CH₄is higher.In contrast, the higher Cu²⁺concentration (400⁶00mg.kg^-1) was more favorable to AME-D inthe landfill cover soil.（3） Both in the aged refuse and landfill cover soil, the efficiency of methane oxidation isclosely related to microbial activity, the higher microbial activity leads to higher methane oxidation efficiency. The organisms in the aged refuse and landfill cover soil both utilized wellamino acid. The data from isotope tracer suggested that nitrate could stimulate themethane-oxidizing bacteria oxiding much CH₄and producing much intermediates，and a certainconcentration of nitrate could promote much NO₃^--N redoxed into other forms of N instead ofN₂in the aged refuse and landfill cover soil.