【正文】 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。 Ostendorf et al., 1984。 Todd and Propper, 1985。 Lockman, 1979。 Shen, 1981。 (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。事實(shí)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?yàn)樗鼈儺a(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(jìn)行 填埋。在氧氣耗盡就標(biāo)志著填埋場厭氧分解來的階段的開始。醋酸分解形成甲烷和二氧化碳。滲濾水的來源主要是降水，灌溉，地表徑流，地下水入侵，還有很少一部分垃圾分解而形成的水分。 4． 1 火災(zāi)和爆炸危險(xiǎn) 雖然垃圾填埋氣甲烷回收是能源恢復(fù)的一個機(jī)會，它往往被 認(rèn)為是不利的，由于其易燃性，它能與空氣形成爆炸性混合物，其有水平和垂直遷移的傾向而擴(kuò)散 到 堆填區(qū)邊界以外。在這個過程中，氧散失，植物根系接觸到垃圾填埋氣體主要成分 是 高濃度甲烷和二氧化碳，由于缺氧會導(dǎo)致植物窒息死亡。這取決于材料的性質(zhì)，滲濾液收集系統(tǒng)的有無，過去 40 年的廣泛調(diào)查的結(jié)果發(fā)現(xiàn) ， 滲濾液與堆填區(qū)底部的含水層接觸 ，會 導(dǎo)致含水層的污染。這些測量可能偏低，由于靠近表面的甲烷氧化菌氧化甲烷產(chǎn)生氧。全球每年的天然氣發(fā)電潛力估計(jì) 是 很大的， 30至 4300 千萬 立方米 ， 但 在與有回收系統(tǒng)的實(shí)際填埋場的甲烷產(chǎn)量數(shù)據(jù)進(jìn)行了對比后上限是有質(zhì)疑的。調(diào)查發(fā)現(xiàn)醫(yī)院垃圾和飛灰，控制甲烷形成和穩(wěn)定，抑制產(chǎn)甲烷堆填區(qū)填埋氣體。填埋氣體的遷移和滲濾污水向堆填區(qū)邊界的外移和以及對周圍環(huán)境釋放是目前新的嚴(yán)重環(huán)境問題，包括潛在的健康危害，火災(zāi)，爆炸，破壞植被，臭氣，垃圾填埋場沉降設(shè)施，地下水污染，空氣污染和全球變暖。 6．結(jié)論 氣體和滲濾污水的產(chǎn)生是廢物處理方法不可避免的后果。 （ 2）被動式排氣 在填埋場邊界設(shè)置一個盲溝，在背部用粗料如礫石（回填）創(chuàng)建一個將被氣體優(yōu)先使用的高滲透率區(qū)域。據(jù)估計(jì)，每年僅在美國天然氣發(fā)電潛力超過六十億立方米。在一個半干旱填埋場 干燥的土壤條件，使用通量箱測量， Bogner 指出，甲烷和二氧化碳通量可高達(dá)630 和 950 公斤高 / m2/yr。 滲濾液是迄今為止對地下水威脅最嚴(yán)重 因素 。損害發(fā)生主要是由于填埋氣 體對植物根部氧氣的直接替換而導(dǎo)致的缺氧。雖然堆填法消除了一些舊的影響，但新的問題隨之出現(xiàn)了， 主要是 填埋 氣體和滲濾液的形成。 3．滲濾液形成機(jī)制 滲濾液形成 是 可溶性物質(zhì)在垃圾中以水的形式不均勻和間歇滲透的結(jié)果。氨基酸和糖轉(zhuǎn)換成副產(chǎn)品如丙酸，丁酸 等揮發(fā)性酸（丙酸，丁酸等揮發(fā)性酸）或直接發(fā)酵形成醋酸。 2． 填埋氣體的形成機(jī)理 在填埋廢物分解的過程中，產(chǎn)生氧氣，導(dǎo)致可降解有機(jī)物迅速與氧氣發(fā)生反應(yīng)，形成形成二氧化碳，水和其他的產(chǎn)物。 關(guān)鍵詞 ： 垃圾填埋場； 固體廢物處理； 生物降解； 氣體和滲濾液的產(chǎn)生； 對環(huán)境的影響； 控制方法 1．引言 在絕大多數(shù)情況下，垃圾填埋仍是最經(jīng)濟(jì)的固體廢物處置方式。 Shen et al., 1990). In addition to gas recovery and active gas pumping, control measures include: (1) the installation of impermeable barriers before site operations to secure the perimeter of the land?ll (cement walls, clay trenches, impervious liner materials such as plastics, rubber, asphalt, polyvinyl chloride, high density polyethylene, etc.)。 Stone, 1978a,b。 Dessanti and Peter, 1984。 Gianti et al., 1984。 Cheremissino? et al., 1984。 Gilman, 1980。 Pohland et al., 1983。 Zehnder, 1978。 Rushbrook, 1983。 Zehnder et al.,1982。 Parker and Williams, 1981。 Young and Heasman, 1985). The extent to which odors spread away from the land?ll boundaries depends primarily on weather conditions (wind, temperature, pressure, humidity). Leachate occurrence is by far the most signi?c