城市生活垃圾填埋初期有机质演化规律研究

为阐明生活垃圾填埋初期有机质演化规律,于填埋场打井采集填埋1～3年3个不同时期垃圾样品,用水浸提制备水溶性有机物(DOM)。采用红外光谱、同步荧光光谱及紫外光谱,对浸提液中DOM的结构和演化特征进行了研究。结果显示,生活垃圾中含有脂肪类、蛋白类、糖类及木质素类物质,在填埋初期,有机质中的脂肪类、蛋白质类、糖类及木质素类物质均发生了降解,羧基、氨类及水溶性芳香结构物质减少,DOM分子量降低。研究结果表明,垃圾填埋初期有机质以降解为主。     

基于温差的规模化生活垃圾干式厌氧发酵工艺的产气特征

以北京某生活垃圾干式厌氧发酵工程为对象,通过对厌氧发酵运行温度与环境气温之间的温差调控,分析了不同季节下中温干式厌氧发酵工艺的产气特征。结果表明,干式厌氧发酵运行温度受环境气温影响较大,夏季平均运行温度最高,VS产气率以夏季和秋季较高,容积有机负荷波动大,不同季节平均容积产气率从高到低依次为：夏季>春季>冬季>秋季。统计分析结果表明,该干式厌氧发酵工程的产气能力与运行温度显著相关(p<0.01),春、夏、冬3季的温差与VS产气率显著相关(p<0.05),秋季温差与缓冲能力显著相关(p<0.05)。因此,在具备较大pH缓冲能力的条件下,加强春秋季变温期的温差调控,通过加温和增加回流比等方式提升春秋季变温期、冬季低温期的厌氧运行温度,并提高夏季容积有机负荷,有助于提高该干式厌氧发酵工程的产气效能和运行稳定性。本研究结果可为工程规模干式厌氧发酵工艺的稳定运行及高效产沼气提供参考。     

生活垃圾填埋场填埋气中挥发性有机物释放规律分析

于2007年2月在上海老港垃圾填埋场选取10个不同填满年限的填埋单元进行填埋气的采样分析,用色谱-质谱技术检测了填埋气中的挥发性有机物(VOCs).检测到脂肪烃、卤代脂肪烃、单环芳烃、醚和酮等5类22种化合物,其中11种为美国环境保护署优先控制污染物,甲苯、乙苯和间,对二甲苯的浓度较高.填满时间距采样时间较近(1～2年)的填埋单元检出的VOCs种类较多,脂肪烃和单环芳烃的浓度随填满时间的增加呈现较明显的衰减特征,而卤代脂肪烃、醚和酮的浓度与填满时间的相关性不显著.检出的5种化合物中,1,1,1三氯乙烷、甲苯和间,对-二甲苯的浓度均低于美国加利福尼亚州环保局推荐的健康阈值,氯乙烯和苯则超过该阈值.     

沈阳地区城市有机垃圾季节变化特性及其对产气影响

以沈阳市某小区城市有机垃圾(BMW)为研究对象,研究其季节特性及其在厌氧消化时产气方面的差异。结果表明,BMW总固体(TS)含量随季节变化明显,春、冬季高于夏、秋季,冬季最高,为17.55%(质量分数,下同),比夏季高3.31百分点,一年中的平均值为15.91%;挥发性固体(VS)含量随季节变化规律与TS相反,夏、秋季略高于春、冬季,夏季最高,为87.20%,春季最低,为85.08%,平均VS为86.10%,整体来看,VS随季节变化不明显。对分类后BMW进行厌氧消化,发现冬季BMW排放量少,但产气潜能却比夏季高8.5%。     

餐厨垃圾处理厂挥发性有机物释放特征

选择目前国内成功运营的餐厨垃圾处理厂为采样点,该厂以利用餐厨垃圾生产生物蛋白饲料和厌氧发酵为主要工艺,采用气相色谱/质谱联用(GC/MS)技术对挥发性有机物(VOCs)浓度较高的工段,如破碎室、湿热反应器、好氧发酵仓进行了定性和定量分析.结果表明,3个采样点共检测出65种物质,包括醇、醛、酮、酯、芳香烃、硫化物、卤代物、烯烃和烷烃9类.湿热反应器排放VOCs浓度最高且包含物质种类最多,其中酮、酯、芳香烃、硫化物、卤代物、烯烃及烷烃类物质浓度均高于其他检测点,需对该工段进行重点监测和控制.     

pH值对玉米秸秆厌氧消化产气的影响

采用批式实验,研究了(35±0.5)℃、搅拌速度65 r/min的厌氧消化体系中,pH值对玉米秸秆厌氧消化产甲烷的影响,分析了消化液相及固相特性的变化.结果表明,厌氧消化第7~9天时各系统VFA浓度均达到最大值,pH值为7和9时,挥发性脂肪酸(VFA)浓度显著高于其他系统,SCOD向VFA的转化效率较高.pH值为9时累积产气量增加速度最快,最大累计产气量达到134.33 mL/g VS.pH值为7时累计产气量最大,高达149.2 mL/g VS,是pH值为5和11系统的3.23和6.71倍.pH值为7和9时,沼气中甲烷的平均含量分别为64.1%和62.5%,比pH值为5和11的系统提高了约10%.pH值为7和9时VS去除率达到67.68%和58.87%,显著高于其他系统.控制厌氧消化pH值在7~9范围内可以有效提高木质纤维素生物质的产气效率.     

脂肪酶对餐厨垃圾厌氧产气的影响

在序批式厌氧反应器中探究了脂肪酶对餐厨垃圾厌氧消化的影响,结果表明脂肪酶能强化甲烷的积累量,且最佳的脂肪酶投加量为0.4 g·L-1,相应的甲烷积累量为356 mL·g-1 VSS,该数值是空白对照组的1.3倍。进一步机理研究表明脂肪酶能够促进溶解性COD的释放,提高生物脱氢酶的活性而减少长链挥发性脂肪酸的积累,进而提高甲烷的积累量。     

模拟成藏填埋垃圾有机质稳定化与产气的阶段性

通过人工构建模拟生物气藏的大型模拟生物反应器,研究模拟成藏填埋城市生活垃圾有机质厌氧降解及生物气化规律及其机理。结果表明,自然温度条件下,模拟填埋垃圾有机质降解和生物气化具有明显阶段性,与pH、ORP、温度等指标的阶段性变化存在相关性。产气阶段最佳条件包括:最适温度范围为31.0～36.0℃;最适pH范围为5.47～6.75,pH中性条件下产甲烷速率最高;ORP最适范围为-428～-541 mV,产甲烷高峰期ORP值为-519 mV,低于前人关于甲烷菌最适ORP的界定范围。每千克挥发性固体总生物气和甲烷产量分别为128.5 L和77.7 L,生物气和甲烷最大产气量分别为118.0 L/d和82.0 L/d,甲烷最大浓度为70.4%,产气高峰期与甲烷浓度高峰期同时出现。模拟成藏填埋垃圾有机质的稳定化过程具有明显的可诱导特征,关键因子的优化对有机质的降解及生物气化产生明显促进作用。     

矿化垃圾对污泥厌氧消化产甲烷的影响

在序批式厌氧反应器中探究了矿化垃圾对污泥厌氧消化产甲烷的影响。实验结果表明,矿化垃圾能够提高甲烷的产量并且提高甲烷的体积分数。当矿化垃圾投加量由0增加到5 g·L-1时,甲烷的产量也由168.9 mL·（g VSS）-1（挥发性悬浮固体）增加到218.6 mL·（g VSS）-1,体积分数由60%增加至70%。然而继续提高矿化垃圾的投加量至7 g·L-1对污泥厌氧消化造成一定的抑制作用。矿化垃圾的存在能够提高污泥中溶解性化学需氧量（SCOD）的溶出,挥发性脂肪酸的积累进而为产甲烷菌提供了充足的消化底物,从而提高了甲烷的产量。     

蔬菜类废弃物甲烷发酵的产气潜能及过程特征

蔬菜废弃物具有适合厌氧发酵的特性。采用Batch实验方法,对5种常见的蔬菜废弃物的产气潜能进行研究,并在此基础上进一步对厌氧发酵过程限制性步骤及物质转化特征进行分析。研究结果表明:5种蔬菜废弃物累积产甲烷量在发酵0～10 d内增加较快,土豆和白菜废弃物产甲烷潜能最大,分别达到102 mL·g-1(VS),和83 mL·g-1(VS),而黄瓜废弃物的甲烷化潜能较低,只有35 mL·g-1(VS)左右。动力学参数拟合表明:土豆和白菜废弃物厌氧发酵水解、酸化、乙酸化和甲烷化各过程转化速率都明显高于其他废弃物,并且各过程最大转化潜能也较其他类蔬菜高出2倍之多。厌氧发酵限制性步骤分析表明,快速水解生成的SCOD不能有效地转化为VFAs,限制了白菜废弃物厌氧消化的后续转化,而VFAs的累积则是胡萝卜、黄瓜和土豆废弃物厌氧发酵的限制性步骤, SCOD以及VFAs同时累积是茄子废弃物发酵过程的显著特征。对各物质发酵过程物质转化特征分析表明,各废弃物由于4 d以后甲烷菌对乙酸的利用减慢,导致丙酸向乙酸的转化减慢而发生累积现象,10 d以后由于产酸过程的减弱,累积的丙酸盐逐渐转化。     

季节性城市生活垃圾成分分析及厌氧消化特性研究

城市生活垃圾的成分及特性随着季节和人类在不同季节的生活习惯而变化,针对我国北方城市研究了一年中不同季节的城市生活垃圾成分特点,对影响厌氧发酵过程的相关成分如总有机碳（TOC）、总氮（TN）、蛋白质、脂肪和还原糖等进行了测定分析。通过厌氧消化实验,测得不同季节城市生活垃圾pH值、日产气量、沼气甲烷含量、甲烷累积量、挥发性脂肪酸（VFAs）和氧化还原电位（ORP）等参数的变化规律,分析相应变化的影响因素。结果表明,二、三季度的含水率分别为64．81％和67．50％,高于一、四季度,一季度发酵原料中蛋白质和脂肪含量分别为12．56％和8．86％,明显高于其他3个季度。一季度甲烷累积量最高,达到17616mL,单位发酵原料的产气量为204．8mL／g,也是4个季度中最高的,说明蛋白质、脂肪等有机成分含量对厌氧发酵过程及结果影响比较明显。为进一步的城市生活垃圾厌氧消化制取生物燃气的工艺条件提供依据。     

Comparison of aerobic and anaerobic biotreatment of municipal solid waste

To increase the operating lifetime of landfills and to lower leachate treatment costs, an increasing number of municipal solid waste (MSW) landfills are being managed as either aerobic or anaerobic bioreactors. Landfill gas composition, respiration rates, and subsidence were measured for 400 days in 200-L tanks filled with fresh waste materials to compare the relative effectiveness of the two treatments. Tanks were prepared to provide the following conditions: (1) air injection and leachate recirculation (aerobic), (2) leachate recirculation (anaerobic), and (3) no treatment (anaerobic). Respiration tests on the aerobic wet tank showed a steady decrease in oxygen consumption rates from 1.3 mol/day at 20 days to 0.1 mol/day at 400 days. Aerobic wet tanks produced, on average, 6 mol of carbon dioxide (CO2)/kg of MSW as compared with anaerobic wet tanks, which produced 2.2 mol methane/kg of MSW and 2.0 mol CO2/kg methane. Over the test period, the aerobic tanks settled on average 35%, anaerobic tanks settled 21.7%, and the no-treatment tank settled 7.5%, equivalent to overall mass loss in the corresponding reactors. Aerobic tanks reduced stabilization time and produced negligible odor compared with anaerobic tanks, possibly because of the 2 orders of magnitude lower leachate ammonia levels in the aerobic tank. Both treatment regimes provide the opportunity for disposal and remediation of liquid waste.     

Characteristic analysis for odor gas emitted from food waste anaerobic fermentation in the pretreatment workshop

Gas chromatography–mass spectrometry, olfactometry, and other related methods were applied for the qualitative and quantitative analysis of the characteristics of odorous gases in the pretreatment workshop. The composition of odorous gases emitted from municipal food waste was also investigated in this study. The results showed that the tested gases are mainly composed of aromatic gases, which account for 49% of the total volatile organic compounds (VOC) concentrations. The nitrogenous compounds comprise 15% of the total concentration and the other gases comprise the remaining 36%. The level of odor concentration ranged from 2523 odor units (OU) m^?3 to 3577 OU m^?3. The variation of the total chemical composition ranged from 19,725 µg m^?3 to 24,184 µg m^?3. Among the selected four sampling points, the discharge outlet was detected to have the highest concentration in terms of odor, total chemical, sulfur compounds, and aromatics. The correlation analysis showed that the odor concentrations were evidently related to the total chemical composition, sulfur compounds, and aromatics (P < 0.05, n = 5). The odor activity value analysis identified the top three compounds, hydrogen sulfide (91.8), ethyl sulfide (35.8), and trimethylamine (70.6), which contribute to air pollution complaint of waste materials.

Implications: Currently, the amount of food waste has rapidly increased, which leads to difficulty in waste management and more odorous gases released as air pollution. In processing of food wastes by anaerobic fermentation, odorous gases are generated, which significantly affect the workers and occupants in the plant. In the pretreatment workshop for anaerobic decomposition, the odorous gases are generated because of the stacking and decomposition of food wastes. The gases emitted mainly consist of organic gases because the food wastes are mainly organic materials. The other odors that comprise 1% of the gases are S-compounds, aromatics, esters, alkanes, and limonene, which result in unpleasant odors that are harmful to the health.     

Municipal solid waste characteristics and management in China

The purpose of this investigation is to evaluate the current status and identify the problems of municipal solid waste (MSW) management in China in order to determine appropriate remedial strategies. This is the first of two papers, discussing primarily the general characteristics of MSW and its management in China. The second paper focuses on specific remedial strategies. MSW generation in China has increased rapidly in the past 20 years from 31.3 million tons in 1980 to 113.0 million tons in 1998. The annual rate of increase is 3-10%. The average generation per capita is 1.0 kg/day (0.38 t/year). Nearly one-half of the waste generated is dumped in the suburbs, where the accumulated quantity has reached 6 billion tons, which has caused heavy environmental pollution. This paper provides information on MSW management in China, such as MSW generation and its physical, chemical, and biological properties. Low calorific value and high moisture content characterize China's municipal waste. Other issues related to MSW management in China are also discussed, including the factors that influence MSW generation quantity and     

城市生活垃圾降解率分析研究

针对城市生活垃圾降解率研究不足的现状,结合室内物理模拟实验,对垃圾温度和垃圾降解率的变化规律进行分析研究。研究结果表明,填埋初期垃圾填埋体温度升高较快,服从三次曲线变化规律;温度对垃圾降解率有重要的影响,单一温度下垃圾降解率随时间变化近似符合微生物生长曲线;不同温度下,温度高,垃圾降解率快,试验证明41.00、45.00℃垃圾降解率最快,垃圾降解率相差不大,可以认为温度高于41.00℃时垃圾降解率可以按照41.00℃时垃圾降解率计算。     

生活垃圾厌氧堆肥产甲烷特性研究

为了更好地利用厌氧处理产生的气体,在介绍模拟厌氧堆肥试验的基础上,对厌氧堆肥产甲烷的基本特性进行了研究。结果表明,在厌氧堆肥开始阶段20d左右,甲烷只有7．8％（质量分数,下同）左右,远远低于32．8％的二氧化碳;而随着反应的进行,二氧化碳呈下降趋势,甲烷先升高后降低,直到反应进行到第70天左右时,甲烷才逐渐高于二氧化碳,片于第90天左右时达到最高值42．0％;此后二氧化碳及甲烷都逐渐降低,但甲烷始终高于二氧化碳。     

混合生活垃圾恶臭特性及评估方法研究

总结了不同区域、不同时段生活垃圾的恶臭特性,发现恶臭特性受垃圾组分、处理处置工艺等因素影响较大,垃圾中转站的主要恶臭组分为乙酸乙酯、甲苯、乙苯等挥发性有机物(VOCs)及氨气,填埋场恶臭组分中含硫化合物和含氧化合物浓度高,堆肥场恶臭组分中苯系物和烃类浓度较高,焚烧厂恶臭组分主要为苯系物。基于复杂多变的生活垃圾恶臭特性,采用综合评分法评价恶臭的环境影响程度,对已报道的生活垃圾恶臭组分进行综合评价,发现生活垃圾降解过程释放的恶臭组分中,二甲二硫、硫化氢、甲硫醇、萘、1,3,5-三甲苯、甲硫醚、甲苯、乙苯、对二甲苯和α-蒎烯等是混合生活垃圾优先控制的恶臭污染物。     

垃圾降解过程中淀粉酶活性测定条件优化

垃圾填埋场中垃圾降解初期,淀粉酶活性对于垃圾填埋场中碳素的转化过程和垃圾填埋场生物学特性的研究有重要意义,而且也可作为垃圾填埋场稳定化机制研究的重要指标之一.以模拟垃圾填埋系统的垃圾为研究对象,通过正交实验(L25(56))对淀粉酶活性的测定条件进行了优化研究.结果表明:(1)正交实验结果表明,对淀粉酶活性测定的影响大...     

Gas chromatographic methods for monitoring of wastewater chlorophenol degradation in anaerobic reactors

Wastewater samples from an anaerobic reactor were extracted with hexane and derivatized with diazomethane (method 1) and with acetic anidride (method 2). Gas chromatography with electron-capture detection (ECD) was employed for separating the parent compound and intermediates trichlorophenols (TCP) and dichlorophenols (DCP) which originated from the penta chlorophenol (PCP) degradation process. The relations between concentrations of PCP, TCP and DCP areas were linear in the range of concentrations of 0.2 to 8 mg/L and 0.025 mg/L to 5 mg/L for methods 1 and 2, respectively. The repeatability of the extraction methods was satisfactory, with variation coefficients lower than 11%. For method 1, at the fortification level of 0.2 mg/L, recovery of PCP, TCP, and DCP was 112%, 74% and 45%, respectively. For method 2, the corresponding recovery values at the fortification level of 0.1 mg/L were 91%, 93% and 103%, respectively. Storage of the frozen samples did not alter their PCP determination properties. The chromatographic methods adapted for chlorophenol determination in wastewater were suitable with relatively simple manipulation techniques. The obtained results were reproducible and allowed identification of intermediates formed during the PCP degradation process.     

Gas chromatographic methods for monitoring of wastewater chlorophenol degradation in anaerobic reactors

Wastewater samples from an anaerobic reactor were extracted with hexane and derivatized with diazomethane (method 1) and with acetic anidride (method 2). Gas chromatography with electron-capture detection (ECD) was employed for separating the parent compound and intermediates trichlorophenols (TCP) and dichlorophenols (DCP) which originated from the penta chlorophenol (PCP) degradation process. The relations between concentrations of PCP, TCP and DCP areas were linear in the range of concentrations of 0.2 to 8 mg/L and 0.025 mg/L to 5 mg/L for methods 1 and 2, respectively. The repeatability of the extraction methods was satisfactory, with variation coefficients lower than 11%. For method 1, at the fortification level of 0.2 mg/L, recovery of PCP, TCP, and DCP was 112%, 74% and 45%, respectively. For method 2, the corresponding recovery values at the fortification level of 0.1 mg/L were 91%, 93% and 103%, respectively. Storage of the frozen samples did not alter their PCP determination properties. The chromatographic methods adapted for chlorophenol determination in wastewater were suitable with relatively simple manipulation techniques. The obtained results were reproducible and allowed identification of intermediates formed during the PCP degradation process.