准好氧和厌氧填埋陈腐垃圾的稳定化特性

比较了5 a填埋龄准好氧和厌氧填埋体陈腐垃圾的挥发性固体(VS)、有机碳(TOC)和腐殖质等降解及稳定化指标。结果表明,陈腐垃圾中VS和TOC含量较新鲜垃圾显著降低,准好氧填埋体陈腐垃圾的VS和TOC含量低于厌氧填埋体1%~2%,但差异不显著;准好氧填埋体的表面沉降量显著高于厌氧填埋体(P0.05),存在一定的负相关关系。渗滤液和清水回灌引起陈腐垃圾VS含量的差异不明显,但造成了填埋体表面明显的不均匀沉降。准好氧填埋体陈腐垃圾的BDM值与厌氧填埋体相近,且随距离导气管距离和填埋深度的增加逐渐升高,距离导气管距离越大,层间BDM值差异越大。此外,准好氧和厌氧填埋体陈腐垃圾的腐殖质提取率与HA/FA差异不明显。     

填埋方式对污泥填埋稳定性的影响

参考垃圾填埋场经验,采用模拟填埋场,对污泥分别进行准好氧填埋和厌氧填埋,并定期监测渗滤液水质,利用指数法对两种填埋场的稳定化进行评价.结果表明,与厌氧填埋相比,准好氧填埋方式下污泥容重、密度和孔隙度的增长速度更快;并且准好氧填埋方式更有利于填埋体中污染物的降解,渗滤液中的污染物浓度更低;准好氧填埋场的稳定化速率要大于厌氧填埋场:准好氧填埋场在封场10周后即可达到二级稳定、渗滤液水质达到二级排放标准,而厌氧填埋场在封场30周后才能达到此标准.     

锯末减量垃圾渗滤液的试验研究

为考察锯末对垃圾渗滤液的减量作用以及在垃圾中添加锯末对其降解速率以及渗滤液中COD和NH3-N浓度的影响,在实验室构建了三个圆柱形垃圾厌氧填埋反应器,用于模拟垃圾填埋场的运行情况,并对垃圾渗滤液的产生量、垃圾层沉降高度、渗滤液中COD和NH3-N的浓度进行了监测。结果表明:锯末具有很强的减少垃圾渗滤液产量和加速垃圾降解的作用,在垃圾层中混合添加锯末能使每升垃圾的渗滤液产生量在180d内减少1200～1300mL,垃圾层高度比不添加锯末时多沉降了5cm;添加锯末后垃圾渗滤液中的COD浓度有所降低;锯末对NH3-N有一定的吸附作用。     

水分运移对填埋垃圾降解过程的影响模拟研究

模拟填埋实验对比研究了渗滤液定期排放、降雨入渗及渗滤液全量回灌对垃圾生物质降解过程的影响,探讨了生物气资源化填埋水分运移的调控措施.结果表明:渗滤液定期排放难以形成产甲烷菌适宜的Eh、pH及湿度条件,垃圾生物质降解表现为持续的水解产酸过程.降雨入渗对环境因子的调控作用微弱,且在入渗水持续冲刷下,CODCr累计净溶出量增加了67.8％.15±2℃下的渗滤液回灌使微生物代谢受到抑制,渗滤液累计产生量与CODCr累计净溶出量分别下降了70.9％与88.5％;反应温度升高至35±2℃,产甲烷菌适宜的环境条件快速形成,但也造成了NH4+-N的快速积累.减少地表水入渗量,合理控制渗滤液回灌温度,并在回灌前进行脱氮处理,可显著提高垃圾填埋处理的无害化与资源化水平.     

垃圾填埋场渗滤液回灌效果的理论研究

基于前人提出的垃圾填埋场渗滤波渗流模型，通过试验初步提出了评价回灌效果的指标和回灌有效期的概念，并分别考察了回灌水质、渗流参数及填埋深度对渗滤液中污染物浓度、微生物浓度和垃圾土中有机质溶解及降解的影响。分析结果表明，回灌能促进渗滤液中COD浓度的降低并加快垃圾土中有机质的降解；提高垃圾土的溶解速度，有利于减少垃圾土的有机质含量，同时不影响COD浓度的稳定；在相同回灌水质下，填埋越深则回灌的效果越不明显。     

收集层结构对准好氧填埋渗滤液水质的影响

在准好氧填埋工艺中,渗滤液收集层可在填埋场底部形成一个好氧生物滤床。采用6组准好氧填埋柱研究了收集层结构对渗滤液降解效果的影响,其中1#～4#柱的渗滤液收集层分别为60、120、180、240 mm高的砾石,5#柱的为180 mm高的卵石,6#柱的为180 mm高的砾石/60mm高的陶粒。监测表明,垃圾填埋柱内的氧浓度表现为上层>中层>下层,具有明显的空间层次效应。经过35周后,对渗滤液中COD、氨氮的去除率分别达到(95.1%～97.7%)、(89.3%～96.8%)。增加渗滤液收集层高度能提高对COD和氨氮的去除率;卵石渗滤液收集层对COD和氨氮的去除效果较砾石的差;在砾石收集层表面增加陶粒可以提高后期对难降解COD的去除效果。     

准好氧填埋垃圾渗滤液全循环处理的影响因素研究

对准好氧垃圾填埋所产生的垃圾渗滤液进行全循环处理,考察了水力负荷和回灌次数对渗滤液除污效果的影响。正交试验结果表明,水力负荷是影响渗滤液中污染物去除效果的关键因素,回灌次数则为次要因素;较优的水力负荷和回灌次数分别为15.9 L/(m2.d)和3次/d,此时对渗滤液中COD、BOD5、NH4+-N的去除率分别为99.3%、99.7%和98.7%。     

厌氧垃圾填埋系统渗滤液的生物毒性研究

以嗜热四膜虫作为毒性试验生物，对厌氧生物反应器垃圾填埋系统渗滤液的生物毒性变化进行了研究。结果表明，通过将渗滤液回灌使其在厌氧生物反应器填埋系统中得到处理，可使渗滤液的生物毒性随填埋时间的延长而逐渐降低；渗滤液的半致死浓度（LC50）与COD呈负相关，其常规理化指标并不能完全反映渗滤液在环境中的生物毒性；较高浓度的渗滤液对四膜虫的呼吸量有抑制作用。     

大型准好氧填埋场渗滤液水质特性的研究

为进一步验证准好氧填埋技术的实用性,在成都市长安垃圾填埋场内进行了三个规模均为10 m×10 m×5 m的准好氧填埋单元试验研究,并分别对渗滤液的pH值、VFA、COD、BOD5和NH4+-N进行了分析.结果表明:对渗滤液中COD、BOD5的降解效果均较好,在分别经过742、704、697 d后,三个单元对COD的去除率分别达到了94.0%、98.0%和96.9%,对BOD5的去除率分别达到了99.4%、99.7%和99.6%;由于受到渗滤液收集管管径较小的限制,对NH4+-N的降解效果较差,因此需要根据准好氧填埋场的规模来调整渗滤液收集管的管径.     

垃圾填埋场渗滤液污染的控制技术

提出准好氧性填埋、渗滤液循环和渗滤液处理等控制垃圾填埋场渗滤液污染的对策,对各种渗滤液处理方案及技术进行了比较系统的分析。     

Biological nitrogen removal from municipal landfill leachate: low-cost nitrification in biofilters and laboratory scale in-situ denitrification

The slow leaching of nitrogen from solid waste in landfills, resulting in high concentrations of ammonia in the landfill leachate, may last for several decades. The removal of nitrogen from leachate is desirable as nitrogen can trigger eutrophication in lakes and rivers. In the present study, a low-cost nitrification-denitrification process was developed to reduce nitrogen load especially in leachates from small landfills. Nitrification was studied in laboratory and on-site pilot aerobic biofilters with waste materials as filter media (crushed brick in upflow filters and bulking agent of compost in a downflow filter) while denitrification was studied in a laboratory anoxic/anaerobic column filled with landfill waste. In the laboratory nitrification filters, start-up of nitrification took less than 3 weeks and over 90% nitrification of leachate (NH4-N between 60 and 170mg N l(-1), COD between 230 and 1,300 mg l(-1)) was obtained with loading rates between 100 and 130 mgNH4-N l(-1) d at 25 degrees C. In an on-site pilot study a level of nitrification of leachate (NH4-N between 160 and 270 mg N l(-1), COD between 1,300 and 1,600 mg l(-1)) above 90% was achieved in a crushed brick biofilter with a loading rate of 50mg NH4-N l(-1) d even at temperatures as low as 5-10 degrees C. Ammonium concentrations in all biofilter effluents were usually below the detection limit. In the denitrification column. denitrification started within 2 weeks and total oxidised nitrogen in nitrified leachate (TON between 50 and 150mg N l(-1)) usually declined below the detection limit at 25 degrees C, whereas some ammonium, probably originating from the landfill waste used in the column, was detected in the effluent. No adverse effect was observed on the methanation of waste in the denitrification column with a loading rate of 3.8 g TON-N/t-TS(waste) d. In conclusion, nitrification in a low-cost biofilter followed by denitrification in a landfill body appears applicable for the removal of nitrogen in landfill leachate in colder climates.     

准好氧填埋场垃圾渗滤液全循环回灌处理研究

将模拟准好氧填埋场垃圾渗滤液进行全循环回灌处理，考察了不同回灌条件对渗滤液稳定化进程的影响。结果表明，不同回灌条件下垃圾渗滤液具有基本相同的稳定化进程，COD和BOD5值均经历了快速下降、稳定下降和缓慢下降3个时期；而氨氮浓度则是先升高后降低。每日回灌总量和回灌频率是影响渗滤液稳定化进程的主要因素：在一定范围内，二者取值越大则渗滤液的稳定化程度越高。     

投加高效菌处理回灌型垃圾填埋场渗滤液的研究

从垃圾转运站被污染的土壤中筛选出1株高效菌，向垃圾渗滤液中投加该菌株进行厌氧摇瓶试验，结果表明该菌株具有较好的厌氧去除氨氮的性能。将该菌株投加于模拟填埋场生物反应器中，进行了为期282d的试验，结果表明，渗滤液中的氨氮与COD被同时去除，第282天时渗滤液中的COD为770mg／L、NH4^＋ -N为90．1mg／L，大大降低了渗滤液后续处理的难度。     

准好氧生物反应器处理渗滤液系统的驯化研究

将准好氧填埋技术与矿化垃圾技术相结合在实验室内构建了模拟准好氧生物反应器垃圾处理系统,以室内埋龄为3年的矿化垃圾填充准好氧生物反应器,以室内模拟垃圾填埋柱产生的新鲜渗滤液为处理对象,考察了混合培养法、容积负荷渐增法和水力负荷渐增法对反应器内微生物的驯化效果.结果表明,混合培养法较负荷渐增法的驯化效果好,在驯化结束时,采用混合培养法的反应器出水COD为305 mg/L,NH3-N为0.6 mg/L,TN为38.7 mg/L;驯化时间越长则驯化效果越好,同是容积负荷渐增法,经过30 d分阶段驯化和经过20 d分阶段驯化的反应器,其出水COD分别为381 mg/L和1 311 mg/L,NH3-N分别为0.8 mg/L和5.0 mg/L.在准好氧生物反应器处理渗滤液系统的工程应用中,对微生物的驯化可首选混合培养法,同时应保证一定的驯化时间.     

Landfill evolution and treatability assessment of high‐strength leachate from msw with high organic and moisture content

The generation of contaminated leachate remains an inevitable consequence of the practice of solid waste disposal in landfills. The collection and treatment of leachate have become common practice in order to prevent environmental pollution. Leachate treatment is highly dependent on the quality of leachate, which in turn is influenced by various factors including waste composition and operational procedures. This paper investigates the treatability of high‐strength leachate from pre‐sorted and baled municipal solid waste characterized by high organic and moisture content. For this purpose, waste disposal and leachate generation rates were monitored. Leachate samples were collected and analysed for selected indicators including BOD, COD, pH, and NH₄‐N and a pilot scale treatment plant with coagulation, precipitation and sequential batch biological reactors was constructed to evaluate the feasibility of leachate treatment. Concentration levels were related to biological activity within the landfill and the results indicated that (1) pre‐sorting and baling of the waste did not hinder waste stabilization; and (2) the high organic and moisture contents resulted in an extremely strong leachate, particularly at the onset of biodegradation processes, which can affect the leachate treatment facility. The effectiveness of the pilot plant in treating the leachate exceeded 90% using COD and NH₄‐N as indicators.     

Removal of non-biodegradable organic matter from landfill leachates by adsorption

Leachates produced at the La Zoreda landfill in Asturias, Spain, were recirculated through a simulated landfill pilot plant. Prior to recirculation, three loads of different amounts of Municipal Solid Waste (MSW) were added to the plant, forming in this way consecutive layers. When anaerobic digestion was almost completed, the leachates from the landfill were recirculated. After recirculation, a new load of MSW was added and two new recirculations were carried out. The organic load of the three landfill leachates recirculated through the anaerobic pilot plant decreased from initial values of 5108, 3782 and 2560 mg/l to values of between 1500 and 1600 mg/l. Despite achieving reductions in the organic load of the leachate, a residual organic load still remained that was composed of non-biodegradable organic constituents such as humic substances. Similar values of the chemical oxygen demand (COD) were obtained when the landfill leachate was treated by a pressurised anoxic-aerobic process followed by ultrafiltration. After recirculation through the pilot plant, physico-chemical treatment was carried out to reduce the COD of the leachate. The pH of the leachate was decreased to a value of 1.5 to precipitate the humic fraction, obtaining a reduction in COD of about 13.5%. The supernatant liquid was treated with activated carbon and different resins, XAD-8, XAD-4 and IR-120. Activated carbon presented the highest adsorption capacities, obtaining COD values for the treated leachate in the order of 200mg/l. Similar results were obtained when treating with activated carbon, the leachate from the biological treatment plant at the La Zoreda landfill; in this case without decreasing the pH.     

The effects of reduction of the deposited waste on short‐term landfill leachate composition of a landfill: a case study in Norway

Municipal solid waste landfill leachate was sampled over from a landfill receiving varying amounts of municipal solid waste. The investigation aimed to provide information on expected leachate changes in the short term, either after closure of an active landfill, or after a strong decline in the amount of waste deposited at smaller landfills. It was found that during a two year period following a sudden decline in the amount of waste deposited, the levels of various chemical and physical parameters all dropped sharply. The reasons for the decline in discharge levels are thought to be aerobic decomposition taking place in the municipal solid waste just after landfilling, and thus the decline in the impact of this process when there were less fresh waste masses available, and formation of preferential flow paths for the leachate as the municipal solid waste stabilized in the landfill.     

Removal of organics from leachates by anaerobic filter

A laboratory-scale study was conducted on two anaerobic filters at several loading rates and four hydraulic detention times. Feed substrates were landfill leachates taken from a recently opened landfill (Keele Valley) and from an older site (Brock North) which had been closed for about 8 years. The strong raw leachate from the new landfill had a COD of 14,000 mg l⁻¹, a BOD/COD ratio of 0.7 and a COD/P value of 17,900. The partially stabilized leachate from the older landfill had a COD of only 3750 mg l⁻¹, a BOD/COD ratio of 0.3 and a COD/P value of 30,640.Results from the treatment of the two leachates were compared with those from a previous study of a “mature” landfill (Beare Road). It was demonstrated that the anaerobic filter could reduce the COD of leachate from landfills of different ages by 90%, at loading rates of 1.26–1.45 kg COD m⁻³ d⁻¹. Total biogas production ranged between 400 and 500 l gas kg⁻¹ COD destroyed and methane content between 75 and 85%. No phosphorus addition was required over the loading range studied.