【作者】 李俊；

【导师】 吴军；

【作者基本信息】 南京大学 ， 环境工程， 2017， 硕士

【摘要】 生活垃圾填埋处理技术作为经济适用环境友好的最终处理技术,由于作业过程大气污染控制困难和占用大量土地资源两大问题,正面临前所未有的发展瓶颈。针对上述问题,笔者提出强化覆盖技术控制大气污染、生物反应器填埋场微元化加速稳定、结合"城市矿山"开采及资源化的循环可持续填埋解决方案。本论文围绕微元生物反应器填埋加速稳定的效果,根据"时空转换"的理念,研究腐殖土批次覆盖、渗滤液预处理后回灌和厌氧+好氧联合运行模式共同作用时生活垃圾的稳定化进程。基于微元生物反应器填埋(Microcell bioreactor landfill,ML)与传统生物反应器填埋(Conventional bioreactor landfill,CL)实验室模拟装置气固液三相稳定化演变规律的对比分析,进行稳定化速率常数分类推演,最终构建微元化技术的时空转换率综合评价方法。此外,为了更直观地确定填埋场的稳定化程度,选取固体垃圾中可降解有机物含量这个角度,研究一种操作便捷和耗时较短的新型好氧测定方法——运用BOD分析仪测定呼吸指数(RI)的可行性与合理性,并尝试建立一套规范的测定操作流程。研究结果表明:通过对四种典型餐厨垃圾组分(米饭、蔬菜、瘦肉和肥肉)的测定结果,发现使用BOD分析仪测定呼吸指数(RI)具有一定的可行性。在测定过程中,样品所处环境中氧气的总量是固定不变的,因此样品质量成为了制约测定结果准确性的主要因素。定义富余系数为所取固体样品彻底矿化时的需氧量跟仪器耗氧量量程的比值,该系数宜在0.2～0.8之间。根据四种典型组分的好氧发酵特性,发现前四天与前十天累积耗氧量的比值(AT4/AT10)基本为0.7～0.8,脂肪类有机物略低(0.6～0.7),因此测试周期设置为4天兼顾了提高效率和保证准确性两方面的要求。RImax受有机底物水解速率的影响容易出现极大值,不能反映好氧降解过程中实际整体情况;RI24h跟AT4的相关性较高,均能有效反映有机物的生物稳定性程度。ML集合了腐殖土批次覆盖、渗滤液预处理后回灌和厌氧+好氧的联合运行模式,跟CL相比,在填埋气组分、垃圾生物稳定性和渗滤液水质等方面具有明显的优势。CL和ML的迟滞期分别为0.35年和0.32年,ML更早进入产甲烷阶段。CL在厌氧阶段的稳定化速率常数为3.40/年;ML在厌氧阶段的稳定化速率常数为4.36/年,在好氧阶段的稳定化速率常数为20.84/年。微元生物反应器填埋的时空转换率为1.28,表明它对填埋场空间的利用效率更高,在单位时间里能够处理更多垃圾。好氧生物反应器填埋(Aerobic bioreactor landfill,AL)在去除渗滤液COD和氨氮方面表现突出,但不能回收生活垃圾的生物质能且能耗较大,建议在填埋场稳定化末期使用。CL、ML和AL填埋模拟装置的渗滤液COD、总氮和氨氮在达到最大值后,均呈现出快速下降再逐渐降低的趋势,符合指数衰减规律。CL、ML和AL的COD降解速率常数分别为0.017 5 d-1,0.024 6 d-1和0.057 1d-1,渗滤液COD在好氧环境中降解速率更大,ML采用腐殖土覆盖并回灌预处理后的渗滤液,有利于加速渗滤液COD的降解。CL和ML的总氮降解速率常数分别为0.0053 d-1和0.0269 d-1 ML的渗滤液经过了厌氧预处理,且腐殖土中大量已驯化的菌群通过硝化和反硝化反应等途径,可以有效降解含氮有机物。由于腐殖土和破碎混凝土砾石的存在,回灌渗滤液能够更加均匀地分布于ML填埋模拟装置各个断面。更高的回灌强度可以加速小分子物质的溶出。腐殖土中大量菌群和渗滤液厌氧预处理措施可以从反应器内部和外部两个方面高效降解渗滤液中的污染物。因此ML中垃圾的生物稳定性比CL高,ML垃圾样品在第154天的厌氧产气率GB21接近德国法规中的限值(20 L·kg-1 DW)。由于好氧稳定过程能够极大地促进有机质的生物降解,AL垃圾的生物稳定性比ML高,AL垃圾样品在第280天的耗氧量AT4接近德国法规中的限值(5 mg O2·g-1 DW)。以上研究结果表明,微元生物反应器填埋技术能够充分地利用填埋时间和空间,促进生活垃圾的快速稳定化,为"干墓式"最终处置场转变成"摇篮式""城市矿山"开采利用场的循环可持续填埋及资源化体系的构建打下了坚实的基础。更多还原

【Abstract】 Landfilling process has been considered as one of the most important final disposal alternatives with respect to its economical and environmently-friendly features for MSW treatment,however it is facing unprecedented development bottlenecks arising from two primary problems including its poor atmosphere pollution control in the process of operation and its nature of occupying much land.In order to solve the above problems,the author puts forward a novel recycling and sustainable landfilling system comprised of three features:enhancing coverage technique to restirict odor gases emission,dividing bioreactor landfill sites into micro cells to speed up stabilization rate,exploiting "urban mine" to reuse resources.The aim of this research is to highlight the effects of accelerated stability of microcell bioreactor landfill.According to the concept of "transformation of time and space",the author plans to study MSW stabilization process when humus daily cover,pretreated leachate recirculation and anaerobic + aerobic joint operation mode are adopted.Based on the lab-scale contrast experiments of microcell bioreactor landfill(ML)and conventional bioreactor landfill(CL)simulators,the evolution of gas generation,solid waste stabilization and leachate degradation were analyzed to deduce the stabilization rate constants respectively,and finally comprehensive assessment method determined as "space-time conversion rate" for ML was established.In addition,in order to gain insight into the landfill stabilization more intuitively,it was studied that a convenient and fast aerobic characterization method of biodegradable organic matter content in the solid waste.The feasibility and rationality of determining respiratory index(RI)with BOD analyzer were assessed and the standardized measurement procedure was attempted to be established.The results indicated that:Based on the determination results of four typical food waste components,such as rice,vegetables,lean and fat,it was found that it is feasible a certain extent to determine the respiratory index(RI)with BOD analyzer.In the process of determination,the total amount of oxygen supply for the sample in the environment is fixed,so sample weight becomes the main factor restricting the accuracy of determination results.Surplus coefficient is defined as the ratio of oxygen demand of the solid sample if completely mineralized to oxygen consumption range of the instrument,and it should be 0.2-0.8.According to the aerobic fermentation characteristics of four typical components,it was found that the ratio of the cumulative oxygen consumption in the previous four days to ten days(AT4/AT10)was 0.7-0.8 and the fat organics was slightly lower(0.6-0.7).Therefore the test time is set to be four days,which takes into account both the need for improving efficiency and ensuring accuracy.RImax was highly affected by the hydrolysis rate of organic substrates,which could not reflect the actual situation in the process of aerobic degradation.RI24h was closely correlated with AT4,both of which could effectively reflect the biological stability of organic matter.ML featured as humus daily cover,pretreated leachate recirculation and anaerobic + aerobic joint operation mode,compared with CL,exhibited better performance in terms of landfill gas composition,MSW biological stability and leachate characteristics.The lag phase of CL and ML were 0.35 yr and 0.32 yr respectively,which meant ML switched into the methanation stage earlier.The stabilization rate constant of CL in the anaerobic stage was 3.40 yr-1,while that of ML in the anaerobic stage was 4.36 yr-1 and that of ML in the aerobic stage was 20.84 yr-1.The space-time conversion rate of microcell bioreactor landfill was 1.28,which indicated that it could make full use of landfill space more efficiently and dispose more MSW in a certain period of time.Aerobic bioreactor landfill(AL)was prominent in the removal of leachate COD and ammonia nitrogen.It is suggested that AL should be adopted in the late stage of landfill operation because it is impossible to utilize the biomass energy and the energy consumption is high.The leachate COD,total nitrogen and ammonia nitrogen of CL,ML and AL landfill simulators showed a rapid decrease and then decreased gradually after reaching the maximum value,which accorded with the exponential decay law.The COD degradation rate constants of CL,ML and AL were 0.017 5 d-1,1.024 6 d-1 and 0.057 1 d-1,respectively.The degradation rate of COD in aerobic environment was higher.ML adopted humus cover and pretreated leachate recirculation,which were beneficial to accelerate the degradation of leachate COD.The total nitrogen degradation rate constants of CL and ML,were 0.0053 d-1 and 0.0269 d-1,respectively.The leachate of ML was pretreated with an anaerobic device,and a large number of acclimated bacteria in humus could effectively degrade nitrogenous organic matter through nitrification and denitrification.Due to the presence of humus and crushed concrete gravel,leachate could be distributed more evenly across the various sections of ML simulator.Higher intensity of leachate recirculation could accelerate the dissolution of small molecules.Contaminants in the leachate could be efficiently degraded from both inside and outside of the reactor because of the large amount of bacteria in the humus and leachate anaerobic pretreatment.Therefore,the biological stability of MSW in ML was higher than CL.GB21 of solid sample in ML on day 154 was close to the limit value in German ordinance(20 L·kg-1 D/W).Since aerobic stabilization process could greatly promote the biodegradation of organic matter,the biological stability of MSW in AL was higher than ML.AT4 of solid sample in AL on day 280 was close to the limit value in German ordinance(5 mg O2·g-1 DW).The above results showed that microcell bioreactor landfill technology could make full use of time and space to promote the rapid stabilization of MSW,which laida solid foundation for construction of recycling and sustainable landfilling system characterized by the transformation from the final "dry tomb" to "cradle" reused as"urban mining".更多还原