【作者】 王丹；

【导师】 尹平河； 赵玲；

【作者基本信息】 暨南大学 ， 分析化学， 2012， 硕士

【摘要】 城市垃圾填埋场作为第三大甲烷排放源不断加剧着全球温室效应。目前中国生活垃圾量高达10亿吨/年，80%以上的垃圾采用卫生填埋方式处理。垃圾在填埋过程中会产生大量以CH₄和CO₂为主的填埋气，填埋气通过垃圾体表面大量逸散到空气中，如何经济有效地控制垃圾体表面甲烷排放，对减缓全球温室效应具有重大意义。本论文以广州市兴丰垃圾填埋场为调研对象，调查了该填埋场气体产生、收集和扩散情况，监测填埋场表面甲烷释放速率，以了解通过垃圾体表面扩散的甲烷量。在此基础上进行了实验室模拟覆盖层的甲烷氧化实验，筛选出既满足工程作业要求又具有高效甲烷氧化能力的生物覆盖材料，优化材料的影响因子和考察材料的甲烷氧化机制，旨在为垃圾填埋场生物覆盖材料甲烷减排的工程应用提供理论。主要结论如下：（1）兴丰垃圾填埋场采用水平收集管道收集填埋气体以用于发电。对该填埋场填埋气体调研分析得出：全场分为4区作业，每区设置3层收集管，三、四区目前为产气活跃期，填埋气收集量分别占总收集效率的37.8%、43.9%。由于收集管管道堵塞问题及收集管布局的不合理导致填埋气收集效率下降，大量气体通过填埋场表层释放到空气中。填埋场采用HDPE膜作为临时覆盖材料，静态箱式法监测到新填作业面和陈垃圾覆膜面的甲烷释放速率分别为0.28mol·m^-2·h^-1和4.17mol·m^-2·h^-1，一年排入大气的CH4量为0.175×107m3，因此控制填埋作业面的甲烷排放是减少填埋场甲烷排放的关键。（2）通过模拟柱实验筛选消化污泥、矿化垃圾和黏土作为潜在的垃圾填埋场覆盖材料，考察其甲烷氧化能力以实现填埋场甲烷减排的目的。实验表明消化污泥和矿化垃圾甲烷氧化能力显著，其对甲烷的日氧化率平均值、总氧化率和氧化速率V（CH4）分别为10.27%、75.82%、1.76mmol/（kg·d）和11.05%、75.61%、2.04mmol/（kg·d），均高于黏土的9.05%、68.15%、1.33mmol/（kg·d）。实验进一步采用粉煤灰、建筑垃圾和黏土作为改性剂，掺入消化污泥中以改善消化污泥的理化性质和甲烷氧化能力。粉煤灰改性后的消化污泥甲烷氧化能力最高，其甲烷日氧化率平均值、总氧化率和V（CH4）分别为17.27%、92.37%、2.35mmol/（kg·d）。粉煤灰不仅发挥了其肥效作用，又起到了疏松剂和膨胀剂的作用，既改善材料理化性质，又显著提高了材料的甲烷氧化能力。因此生物覆盖材料粉煤灰改性污泥的甲烷氧化能力比传统覆盖层强，可以作为潜在的填埋场甲烷减排技术加以应用。（3）通过测定粉煤灰改性污泥的土工性质，实验得出粉煤灰与消化污泥混合比在1:1～1.5:1范围内，渗透系数＜10-4cm/s，抗压强度≥50kPa，可以满足填埋场作业要求且粉煤灰明显降低了消化污泥的臭度和粘度。L9（34）正交实验优化材料各影响因子得出材料最佳条件为粉煤灰与消化污泥以1:1的混合比，添加0.05mL/g的NMS营养液调节其含水率为40%，200mm覆盖厚度作为日覆盖厚度，400mm作为区覆盖或终场覆盖厚度。在最优条件下，材料的甲烷总氧化率可达到88.6%。（4）生物覆盖材料受下层填埋气中CH4浓度和上层空气扩散到材料中的O₂的影响，材料的甲烷氧化效率随着初始CH4、O2浓度的升高而增加。覆盖材料的甲烷氧化反应以CH4和O2为主要反应物。在室温条件下，通过测量CH4与O₂的反应速率以建立CH₄氧化动力学方程。实验得出材料的甲烷氧化速率方程为：-dV（CH₄）/dt=kV（CH₄）V（O₂），属2级动力学方程。甲烷浓度越高甲烷氧化速率越大，当土壤中的甲烷浓度饱和时甲烷氧化速率趋于平稳。通过动力学Michaelis-Menten模型，利用Origin version7.5软件拟合得出最大反应速率V max为2.54μmolCH4g^-1h^-1，半速常数K m为0.49μmol。更多还原

【Abstract】 Waste landfills were the third anthropogenic methane emission source on earth which effecton the global climate. At present1billion tons of municipal solid wastes are produced a year inchina,80%of refuse was treated by a sanitary landfill according to the conditions of our country.Landfill gas（LFG） which mainly consisting from methane and carbon dioxide was produced inlandfills and a great amount of LFG was emitted into the air. How to control LFG emission has agreat significance in help reduce global warming. The object of this research is Xingfeng wastelandfill in Guangzhou, LFG collection and emission system was realized and methane emissionsource of landfill was found out by monitoring the methane emission rate. On this basis, thelandfill bio-cover which meets the engineering demand and methane oxidation were selectedthrough simulation columns experiment, optimize material compositions and exam dynamicmechanism can provide theoretical basis and technical support for engineering application. Themain conclusions are as follows:（1） Xingfeng waste landfill is providing electricity to the local power grid through thecollection and recovery of landfill gas for power generation. The landfill divided into fourdistricts, each district set three layers pipeline for collection LFG. The third and fourth districtsare in gas generation phase, the LFG collection rate reached37.8%and43.9%. Because thepipeline get clogged and unreasonable layout, the LFG collection rate decreases which cause agreat amount of LFG was emitted into the air.The emission rates of methane in fresh andmatured refuses were0.29mol·m-2·h^-1and4.17mol·m-2·h^-1, respectively. The emission rate ofmethane was0.175×10⁷m³·a^-1. The methane emission from operating area should be controlledin order to promote methane reduction.（2） The methane oxidation of3bio-covers （sewage, aged refuse and soil） was studiedthrough simulation experiment. The results showed that average daily methane oxidation rate,methane conversion and reaction rate V（CH₄） of sewage, aged refuse and soil were10.27%,75.82%,1.76mmol/（kg·d）;11.05%,75.61%,2.04mmol/（kg·d） and9.05%,68.15%,1.33mmol/（kg·d） respectively. The methane oxidation capacity of sludge and aged refuse were betterthan soil. Methane oxidation and physicochemical property of sludge which were modified by3solid modifiers （coal ash, construction wastes and soil） were also studied. Sludge modified by coal ash presented best ability for methane oxidation among the3modifier, which average dailyoxidation rate, methane conversion and V（CH₄） were17.27%,92.37%,2.35mmol/（kg·d）. Notonly coal ash plays fertilizer effect, and makes the sludge loose and expands. The sludgemodified by coal ash ameliorated physical and chemical properties and improved methaneoxidation ability. Taking the bio-cover as landfill cover can oxidize methane more effectivelythan traditional soil cover layer, and maybe a latent technology for landfill methane emissionreduction.（3）The engineering requirements of osmotic coefficient and compressive strength for covermaterial of landfill site were satisfied when the maxed ratio of coal ash and sludge are1:1^-1.5:1.Full factorial34experimental design using simulation columns was conducted to investigatestatistically the effects of mixed ratio, moisture content, nutrient addition and cover thickness onthe CH₄oxidation efficiency through a landfill bio-cover sewage sludge modified by coal ash.The results from all experiment sets showed that the optimal conditions was1:1mixed ratio ofcoal ash and sewage sludge, added0.05mL/g NMS nutrients to400mm thickness in landfillbio-cover which made moisture content of material reached40%. The maximum CH₄oxidationefficiency was88.6%under the optimal conditions.（4） The methane oxidation efficiency of landfill bio-cover was influenced by methanecontent in LFG and oxygen content in air, the more of methane and oxygen, the higher ofmethane oxidation efficiency. Kinetic equation and parameter were also determined, resultsshowed that the kinetics of methane oxidation was conformed to the second-order reaction,which equation was-dV（CH₄）/dt=kV（CH₄）V（O₂）. The kinetic parameter were done byMichaelis-Menten equation, V（CH₄） initially with methane concentrations increases, until thebio-cover of methane concentrations saturated. The largest methane oxidation rate（V max）was2.54μmol CH₄g^-1h^-1,the apparent half saturation constant（K m） was0.49μmol.更多还原