Study on oxygen-gas penetration mechanism and consumption reaction in sanitary landfills

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The following conclusions were obtained.1. On air flow in a pipeline network in a sanitary landfill(1) A considerable amount of air can flow into the pipelines when every end of pipeline network is open to the atmosphere. (2) The driving forces of air flow are temperature difference between the atmosphere and landfill layer, and suctim pressure by a wind velocity potential on the surface of a landfill site. (3) Therefore, gas composition in pipelines is nearly the same as the atmosphere. (4) Air flow rate in pipelines is influenced by some factors, such as temperature of pipe wall, wind velocity on landfill surface, depth of landfill layer, and clogging in pipelines.2. On oxygen penetration through landfill layer from pipelines(5) Main mechanism of oxygen penetration through layer is ordinary molecular diffusion with oxygen concentration difference. (6) The flux and depth of oxygen penetration are influenced by some factors , such as pore structure, reaction rate of oxygen consumption … More in the layer and oxygen concentration in pipelines. (7) In order to increase amount of oxygen penetrating, some design or management technique are required, such as appropirate design of pipe line network, prevention of very fine particle such as silt, clay and sludge from landfilling.3. On experimental study about removal ability of soluble BOD in aerobic landfill layer(8) In aerobic refuse or crushed stone layer, active biodegradation occurs and the rate of oxygen consumption is equal to that of TOC removal reaction, which is described by the Monotype equation, using oxygen gas concentration in the layer. (9) Oxidation rate of ammonuium-nitrogen is very low, compared with one of organic carbon.4. On estimation of BOD removal potential in the neighborhood of actual bottom leachate discharge pipe(10) Depth of aerobic zone round leachate discharge pipe in incineration residue, incombustible refuse and mixed refuse landfills is 0.5, 2 and 0.2m respectively. Therefore BOD removal ability in sixed refuse layer is estimated to be very low, but ones in incombustible refuse and crushed stone layer are estimated to be high, that is, several thousands mg/L of BOD can be removed. (11) A stabilization mechanism of leachate BOD in semi-aerobic landfills is considered to be biodegradation in aerobic zone round bottom leachate discharge pipes. Less