【正文】 區(qū)分解階段有很大的關(guān)系 。醋酸分解形成甲烷和二氧化碳。 研究人員在有機材料轉(zhuǎn)換為甲烷和二氧化碳 的過程中 已經(jīng)發(fā)現(xiàn)了很多重大步驟來描述厭氧的階段，這些步驟是高度相互依存的，包括水解，酸化，酸形成期和甲烷形成期。在氧氣耗盡就標志著填埋場厭氧分解來的階段的開始。 多數(shù)有機材料可生物降解，能在好氧和厭氧微生物的作用下降解為簡單化合物，這就產(chǎn)生氣體和滲濾液的形成 。事實上，根據(jù)相關(guān)資料，當(dāng)今世界上有 95％的固體廢物產(chǎn)生是通過填埋 ， 這種方法處置的垃圾填埋被稱為是減量化工藝，因為它們產(chǎn)生的廢物組分（比如燃燒過程產(chǎn)生的飛灰能產(chǎn)生二次污染），其最終必須 進行 填埋。除了包括一些潛在的健康危害外，這些問題還可能引發(fā)包括：火災(zāi)，爆炸，破壞植被，臭氣，垃圾填埋場 不均勻 沉降，地下水污染，空氣污染和全球變暖等問題。 (3) a hybrid system consisting of any bination of impermeable barriers and an active or passive system (Alzaydi, 1980). Injection of lime slurry and ?y ash has also been reported to control methane formation and stabilize land?lls by inhibiting methanogenesis and stopping land?ll gas generation (Kinman et al., 1988). Leachate position can be controlled to a limited extent by close monitoring and sorting of land?ll waste. However, deposition byproducts dissolved in in?ltrating water will result in a leachate with elevated concentrations of numerous hazardous chemicals. Leachate treatment is often necessary to reduce these concentrations to levels that meet regulatory requirements. Most biological, physical and chemical processes used for the treatment of industrial wastewater have been tested for treatment of land?ll leachates (Pohland and Harper, 1986). The selection of a particular treatment process will depend on the quality and strength of the leachate. 6. Summary and conclusions Gas and leachate generation are inevitable consequences of the practice of waste disposal in deposition, climatic conditions, refuse characteristics and land?lling operations are amongst the many factors contributing the gas and leachate generation at land?ll sites. The migration of gas and leachate away from the land?ll boundaries and their release into the surrounding environment present serious environmental concerns at both existing and new facilities including potential health hazards, ?res and explosions, damage to vegetation, unpleasant odors, land?ll settlement,ground water pollution, air pollution and global warming. An overview of gas and leachate formation mechanisms in land?lls and their associated adverse environmental impacts was presented and a description of control methods to eliminate or minimize these impacts was provided. In most cases the installation of a gas recovery, collection and treatment system will assist in preventing gas migration away from the land?ll boundaries or gas emissions through the land?ll surface. Hydraulic barriers (. extraction and relief wells, gradient control wells and trenches) and collection systems are monly used to control leachate problems. 7． References Abriola, L. and Pinder, G. F. (1985). A multiphase approach to the modeling of porous media contamination by organic pounds, 1. equation development。 Ghassemi et al., 1986。 Shen, 1981。 Wiqwist, 1986。 Lockman, 1979。Marchant,1981). The energy represented by this gas could meet 1% of the total energy needs or5% of the natural gas utilization in the . (Lytwynyshyn et al., 1982). Reported estimates of worldwide annual gas generation potential vary widely, 30 to 430 billion m3 (Bingemer and Crutzen, 1987。 Todd and Propper, 1985。 Young and Parker, 1983。 Ostendorf et al., 1984。 Kelly, 1976。 Arthur et al.,1985). The damage occurs primarily due to oxygen de?ciency in the root zone resulting from a direct displacement of oxygen by land?ll gas. In the absence of a gas control measure, land?ll gas can migrate upward due to concentration and pressure gradients, and escape into the atmosphere by venting through the land?ll cover. During this process, oxygen is displaced and plant roots are exposed to high concentrations of methane and carbon dioxide, the two major constituents of land?ll gas. The lack of oxygen causes the death of plants of asphyxia. . Unpleasants Odors are mainly the result of the presence of small concentrations of odorous constituents (esters, hydrogen sul?de, organosulphurs, alkylbenzenes, limonene and other hydrocarbons) in land?ll gas emitted into the atmosphere (Young and Parker,1983, 1984). The odorous nature of land?ll gas may vary widely from relatively sweet to bitter and acrid depending on the concentration of the odorous constituents within the gas. These concentrations will vary with waste position and age, deposition stage and the rate of gas generation, and the nature of microbial populations within the waste, amongst other factors. Although many odorous trace pounds may be toxic, they have historically been perceived more as an environmental nuisance than as a direct health hazard (Young and Parker, 1984。 Leone et al., 1977。 ground water intrusion, and to a lesser extent, the initial refusemoisture deposition due to microbial activity may also contribute to leachate formation but in smaller amounts. The quantity of leachate generated is sitespeci?c and a function of water availability and weather condit