生物反应器填埋场系统中有机垃圾降解特性研究

针对渗滤液回灌型生物反应器填埋场中存在着有机酸积累的问题，试验将产甲烷反应器作为渗滤液回灌前的预处理设施引入生物反应器填埋场，研究了其系统中有机垃圾的降解和产气规律。结果表明，在本模拟试验条件下，有机垃圾在填埋场、产甲烷反应器和生物反应器填埋场系统的总产气量分别为62.1、456和518.1 L，其中产甲烷反应器产气量占生物反应器填埋场系统产气量的88％以上。在产甲烷反应器中产气速率与有机物去除率成正比，回归系数为0.4614 L/g COD。基于生物反应器填埋场系统中有机物降解的特征，建立了其产气动力学模型。该模型可用来初步估算相关生物反应器填埋场系统中填埋垃圾稳定化所需时间及产气量，为系统填埋气的能源化利用提供理论依据。     

Optimization of Culture Conditions for the Biodegradation of Lindane by the Polypore Fungus Ganoderma australe

The performance of a lab-scale model biofilter system was investigated to treat CH₄ gas emitted from modern sanitary landfills using landfill cover soil as the filter bed medium. From the batch experiment to measure the influence of moisture content and temperature of the filter medium on CH₄ removal capacity of a biofilter system, the optimum moisture content and temperature were found to be 10–15% by weight and 25–35°C, respectively. From the model biofilter experiment to measure the influence of inlet CH₄ concentration and landfill gas inflow rate on CH₄ removal capacity of a biofilter system, it was found that the removal percentage of CH₄ increased as the inlet CH₄ concentration decreased. Up to a landfill gas inflow rate of 1,000 mL min^?1 (empty bed retention time?=?7.7 min), the CH₄ removal efficiency of the biofilter was able to reach 100%. Up to CH₄ loading rate of 278.5 g CH₄ m^?3 h^?1, the ratio of elimination capacity to CH₄ loading rate was 1 while they were 0.68 and 0.34 at CH₄ loading rate of 417.8 and 557.1 g CH₄ m^?3 h^?1, respectively. The CH₄ removal by biofilter was also confirmed by measuring the change of temperature and moisture content of the filter medium in the model biofilter. The results demonstrated that the installation of a properly managed biofilter system should be effective to reduce atmospheric CH₄ emissions from modern sanitary landfills at the low CH₄ generation stage.     

Influence assessment of landfill gas pumping

Changes in CH₄ gas concentrations arising in a landfill as a consequence of a number of gas extraction pumping rates, are characterized. The field-monitored results indicate a fairly free flow of gas through the refuse. High pumping rates impact large expanses of the landfill site and may deplete the CH₄ levels in the surface regions of the refuse.     

填埋场陈垃圾对黑麦草种子发芽的影响

非正规垃圾填埋场的治理和陈垃圾的资源化利用是环保领域一项重要而迫切的任务。选择黑麦草作为试验对象,采用种子发芽的陆生生态毒理方法,研究陈垃圾对植物发芽的影响,以期为陈垃圾利用和非正规垃圾填埋场治理提供一种新的思路。培养基质中陈垃圾的比例分别为20%、80%和100%,使用蒸馏水和土壤作为对照。试验结果表明：陈垃圾的使用能够显著提高黑麦草种子的发芽势和发芽率,但黑麦草种子的发芽势和发芽率随着陈垃圾用量的增加呈现先增大后减小的特征,陈垃圾在培养基质中的最佳比例为80%,与空白和使用土壤作为培养基质相比,发芽率分别提高了34.3%和20.9%,发芽势分别提高了52.0%和24.0%。培养基质中添加陈垃圾有利于黑麦草种子根、芽的发育和生长,在培养基质中陈垃圾的比例为80%的条件下,黑麦草种子的根长、芽长和芽的鲜质量分别比使用土壤时增加了50.0%、46.9%和74.0%。因此,将稳定后的陈垃圾用于草坪种植是可行的,这为陈垃圾的资源化利用提供了一条新的途径。     

Methane dynamics of landfill cover soils and aspects of their classification

The methane dynamics of soils covering a landfill in Oldenburg, Lower Saxony, was investigated in 1996. The methane concentration was often < 20 nmol (dry g)^?1 within the cover layer and up to 9950 nmol (dry g)^?1 within the refuse body. The methane production rates correlated positively with the methane concentrations and were mostly < 10 nmol (dry g)^?1 d^?1 within the cover layer and up to 1090 nmol (dry g)^_1 d^_1 within the refuse body. The methane oxidation rates varied between 38.0–2310 nmol (dry g)^?1 d^?1. The methane emission rates showed values of up to 574 mol m^?2 h^?1, but in two cases no emission of methane was found. The data indicate that the methano-genesis of the deep refuse layers did not substantially affect the methane behaviour of the upper soil sections. It is likely that the emission of methane from landfills can be reduced by thick well aerated cover layers. The term “Reduktosol” for landfill soils is critically discussed.     

填埋场中硫化氢恶臭污染防治技术研究进展

硫化氢是垃圾填埋场恶臭污染的主要贡献者之一,填埋场中的硫化氢恶臭污染不仅危害现场工人的身体健康,而且影响周围居民的正常生活。该文概述了垃圾填埋场中硫化氢恶臭的污染状况和特征,从硫化氢的源头控制和末端治理两方面阐述了垃圾填埋场硫化氢恶臭防治技术的研究进展。目前,有关填埋场硫化氢恶臭的控制技术主要集中在末端处理,如对填埋气中的硫化氢进行净化或者采用高效的覆盖层材料来减少硫化氢释放,而对于填埋场内的源头控制手段还非常有限。该文着重提出了利用填埋场堆体内部含量丰富的铁资源的微生物氧化还原以及反硝化脱硫菌的特征代谢作用进行硫化氢的内源削减两大方法,并探讨了其他相关技术的发展趋势,对完善填埋场的硫化氢恶臭污染控制理论与实践具有参考价值。     

Characteristics of landfill leachates and alternatives for their treatment: A review

Sanitary landfilling is the most common way to eliminate solid urban wastes. An important problem associated to landfills is the production of leachates. The factors determining the characteristics of leachates from solid urban waste landfills are reviewed together with the reported compositions of leachates from various countries and origins. New data obtained from two landfills of different age in the same area are reported. The advantages and disadvantages of the various existing alternatives for solving the leachates problem are discussed under the items: (1) Leachate Channeling (Combined Treatment with domestic sewage, Recycling and Lagooning with recycling). (2) Biological Processing (Aerobic and Anaerobic). (3) Chemical/Physical Treatment (Chemical Precipitation, Chemical Oxidation, Adsorption onto activated carbon, Reverse osmosis, and Stripping of NH₃). The performance at several operational conditions of the most important methods is reviewed and summarized in several tables. From all this information a table designed to aid the choice of solutions for each particular case is presented.     

垃圾填埋场恶臭污染对感官影响的评价研究

目前中国大气环境影响评价导则中缺少恶臭感官评价因子,实际工作中,多规避或以常规大气环境影响评价方法进行评价。针对这一问题,该文调查总结不同国家和地区恶臭标准、导则及文献,以某垃圾填埋场为例,通过模型模拟、敏感点现场嗅探监测及厂界监测等多种工具得到臭气浓度、臭气强度、恶臭发生频率等评价因子,研究中国恶臭污染的感官环境影响评价方法。结果表明,恶臭源调查结果显示,该垃圾填埋场恶臭管控措施较好,但当扩散条件较差时,厂界恶臭强度可达到4级(强烈的臭味);模型模拟结果显示,厂界臭气浓度可达到1 000以上且恶臭发生频次较高;现场嗅探监测结果显示,距厂界1km范围内2#(西方向)、6#(东北方向)监测点受该垃圾填埋场的恶臭影响较为严重;该垃圾填埋场周边不同方位上距恶臭源0.3～2.8km范围内的敏感点受垃圾干扰相对较高,不同方位上距恶臭源1.8～4.0 km范围外的敏感点受垃圾干扰相对较低;针对厂界东侧3～4 km范围内某一居民区来说,其居住的居民可感知恶臭,但由于恶臭发生频率较低且强度相对不高,整体来说居民区受到该垃圾填埋场的恶臭干扰程度相对较低。     

The impact of gas extraction on landfill-generated methane gas levels

The changes measured in landfill-generated CH₄ gas levels in response to continuous pumping from an augered borehole in the refuse are described. The results of statistical analyses of concentration and pressure levels at a series of probes located radially outward from the gas extraction well are used to characterize the temporal and spatial variations. A drawdown curve arising from the continuous pumping is apparent and is quantified as a series of cones of varying impacts on percentages of CH₄. The results are indicative of a fairly free flow of gas through the landfill.     

城市垃圾填埋场植被恢复研究进展

城市垃圾填埋场占用了大量的城市用地,并使得许多可利用资源如适量的碳、氢、钾、钙、镁、磷和微量的铁、锰、铜等元素被浪费,而且污染并破坏了周围的生态环境,有时候还引起爆炸。如何对封场后的城市垃圾填埋场进行合理高效的开发利用,成为国内外学者研究的热点。通过回顾国内外城市垃圾填埋场土地利用方式、绿化潜力、树种选择研究进展,对垃圾填埋场存在的诸如填埋气体、渗漏问题、植物的养护、土壤贫瘠等对垃圾填埋场绿化产生限制的因子进行探讨,提出找到垃圾填埋场绿化的综合配套技术如绿化美化规划方法、适宜的草种和树种、配套的绿化方法等将成为今后研究的重点与热点。     

Greenhouse gas accounting for landfill diversion of food scraps and yard waste

Diverting organics from landfills to compost piles is generally recognized as a means to reduce greenhouse gas emissions. This article provides a detailed review of the Climate Action Reserve (CAR) and the U.S. EPA Waste Reduction Model (WARM) protocols on landfill diversion and composting for food scraps and yard waste. The primary benefits associated with diversion are methane avoidance. The equations used to quantify methane avoidance include first-order decay rate constants for different feedstocks to predict how quickly organics will decay. The total methane generation potential of the different feedstocks is also included. The equations include estimates of gas collection efficiencies in landfills. The decay rate constants have been determined from laboratory incubations and may not be representative of decomposition within a landfill. Estimates of gas capture efficiency have been improved and more closely reflect actual landfill conditions. Gas capture efficiency will vary based on landfill cover material, portion of the landfill where measurements take place, and whether the gas collection system is operational. Emissions during composting are included in these calculations. Only the WARM model includes a consideration of benefits for compost use. Nevertheless, significant benefits are recognized for landfill diversion of food scraps. The WARM model suggests that landfilling yard waste is superior to composting.     

Effect of municipal landfill leachate on mercury movement through soils

The effect of solution composition on the movement of Hg ions through soils was studied. Three solutions spiked with HgC1₂ were passed through four different soils. The solutions were 0.25 mM Na₂ EDTA, simulated sanitary landfill effluent, and deionized water. The Hg ions were found to be more mobile in the effluent from the simulated landfill than in the other solutions. The formation of mercurous ions and the presence of organic matter seem to be the major contributing factors for Hg; movement through soils in simulated landfill effluent.     

Assessment of the State of Soils and Vegetation in Areas of Landfills and Municipal Solid Waste Sites (a Review)

An overview of modern ideas on the ecological and geochemical state of soils and vegetation in the sites of landfills and municipal solid waste storage is presented. The technogenic impact on the environment and soil is determined by the (1) withdrawal of land for landfills, (2) production of filtration water with toxic components upon decomposition of solid wastes, and (3) biogas generation. The heavy metal pollution of surface soil horizons is characteristic for the sites of solid waste storage and their impact zones irrespectively of climatic conditions, ways of waste management, and stages of the life cycle. At the same time, heavy metals accumulate in ruderal herbaceous plants. Changes in the geochemical and microbiological characteristics of soils and disturbances in the plant cover are not restricted to the area of the designated sanitary protection zone. Buried landfills, where the decomposition of organic matter under anaerobic conditions results in the production of carbon dioxide and methane with their concentration in the soil and ground air also become dangerous for the environment. In the sites of landfills and municipal solid waste storage, weakly developed surface and chemically transformed soils, technosols and technogenic surface formations are being formed.     

The Use of Biofilters to Reduce Atmospheric Methane Emissions from Landfills: Part I. Biofilter Design

Previous laboratory research has shown that biofilters have the potential to reduce CH₄ emissions from landfills by as much as 83%. However, to achieve this level of CH₄ reduction biofilters must be properly designed. The present study was conducted to develop a method for properly designing biofilters based on landfill size and location. A quadratic equation was developed to describe the dependence of CH₄ oxidation rate in a sandy loam textured soil as a function of soil temperature, soil moisture and ammonium nitrogen concentration. Using this equation and the average monthly soil temperature and moisture contents for the largest cities of each of the 48 contiguous states, the monthly CH₄ oxidation rate at each location was calculated. Then, assuming a standard landfill depth of 27.6 m, and a standard area of 121,500 m², the required biofilter size was calculated. Finally, the ratio of biofilter size to landfill size was calculated. Design calculations for biofilters located in the states of Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Texas where the CH₄ oxidation rates are relatively high throughout the year indicate that the necessary biofilter sizes are small. In addition, biofilters in these states may be expected to be effective throughout the year. In contrast, the calculations indicated biofilter systems in the states of Idaho, Minnesota and North Dakota will have much lower efficiencies during much of the year due to unfavorable soil moisture and temperature ranges. Given proper design, installation and management, a biofilter should be capable of achieving a significant reduction in atmospheric CH₄ emission as compared to emissions from the same landfill without a biofilter.     

Acute and genetic toxicity of municipal landfill leachate

The large number of municipal solid waste (MSW) landfills and the many hazardous materials which they contain pose a serious environmental threat to our groundwater reserves. The present study was conducted to assess the environmental hazards that four MSW landfill leachates pose to the groundwater. Genetic toxicities of the landfill leachate and groundwater samples were assessed using the Salmonella/microsome (Ames test) mutagenicity bioassay, the Bacillus subtilis DNA repair bioassay, and the diploid Aspergillus nidulans chromosome damage bioassay. Acute toxicities of the leachate samples were assessed using the Microtox test. The leachate and groundwater samples were also analyzed for organic constituents using gas chromatography and gas chromatography/mass spectrometry. The chemical data were used to calculate the estimated cumulative cancer risk for each sample. All leachate samples were acutely toxic, and three of the four leachate samples were genetically toxic. Two of the four leachate samples and the groundwater sample contained concentrations of USEPA priority pollutants in excess of promulgated standards for potable water. Two of the leachates had mean estimated cumulative cancer risks on the same order of magnitude (10^?4) as leachates from co-disposal and hazardous waste landfills. The use of a battery of acute and genetic toxicity bioassays, chemical analysis, and an estimated cancer risk calculation resulted in evidence that MSW landfill leachates are as acutely and chronically toxic as co-disposal and hazardous waste landfill leachates.     

垃圾填埋场空气微生物浓度的时空分布特征

为了了解垃圾填埋场空气微生物浓度的时空分布及变动规律,在北京市某垃圾卫生填埋场填埋区、渗滤液处理区、生活区分别选定监测点,利用安德森六级微生物采样器,对填埋场空气微生物进行了系统的定点取样和分析。结果表明,垃圾填埋场空气微生物浓度分布填埋区〉渗滤液处理区〉生活区。填埋区空气微生物浓度达到6 000 CFU·m^-3以上,生活区约为3 500 CFU·m^-3,填埋区空气微生物浓度显著高于生活区（P〈0.05）。填埋区不同时段空气微生物浓度不相同,呈4—7月份9：00—11：00浓度低于15：00—16：00,而8、9月份以后9：00—11：00浓度高于15：00—16：00的趋势,但没有统计学差异（P〉0.05）。2006年4月—2007年1月空气微生物总浓度变化曲线呈双峰型,两个高峰分别出现在5月和9—11月。填埋场环境温度对空气微生物浓度的影响大于湿度。     

矿化垃圾中植物大量营养元素含量的剖面分布特征

对经长期填埋后已稳定化的垃圾进行开采和资源化利用,能增加现有填埋场库容,对解决城市生活垃圾填埋场紧张的现状具有重要意义。以一个已运行10a以上的垃圾填埋场为研究对象,对已填埋6、8、10a的矿化垃圾中一些植物大量营养元素的剖面分布进行了测定。结果表明：（1）矿化垃圾中氮、磷、钾养分的浓度总和已达到国家有机肥养分含量标准,有机质含量也明显高于土壤的有机质含量,从植物养分供应的角度看,矿化垃圾可具有资源化利用的价值;（2）矿化垃圾中养分主要以氮素为主,磷、钾营养元素的总量较低,但速效态含量相对较高;（3）不同填埋深度的矿化垃圾中,主要营养元素的含量大部分在填埋8~10a后达到相对稳定的状态,但受矿化垃圾组成成分复杂性的影响,部分形态营养元素的变化规律不明显。     

Reductosols: Natural soils and Technosols under reducing conditions without an aquic moisture regime

According to the German soil classification, Reductosols (German: “Reduktosole”) are soils with a redoximorphic color pattern, but without water saturation for lengthy periods. They are formed by reducing conditions due to oxygen deficiency caused by the accumulation of reduct gases such as CH₄, CO₂, NH₃, or H₂S in the soil atmosphere. Soil oxygen may have been displaced by the ascent of CO₂ from post‐volcanic mofettes or by CH₄ from sanitary landfills. Furthermore, a lack of oxygen causing redoximorphism can occur in unsaturated soils if they contain or receive large quantities of easily decomposable organic matter (i.e., organic urban waste or sludge). Under such circumstances, a gleyic color pattern (e.g., an oxidized Bg horizon above a Cr horizon with strongly reducing conditions) forms without the influence of an aquic moisture regime. Waste‐water and petrol infiltration in soil can form a stagnic color pattern without the stagnation of surface water. Such more or less well‐drained but strongly redoximorphic horizons should be named as Yg instead of Bg. In some cases, such soils only exist for a short time due to the loss of reduct gases or termination of infiltration of organic liquids. Reductosols are ecotops with oxygen deficiency. Natural Reductosols dominate in recent and former volcanic areas, whereas Reductic Technosols are formed in urban‐industrial agglomerations. Their morphology, chemistry, dynamics, genesis, and ecology is summarized and discussed in this paper. Natural gas and CO₂ gas are deposited in deeper zones of the earth crust since some time. Leakages of these depots let form reductosols as well.     

Tropical macrophyte degradation dynamics in freshwater sediments: relationship to greenhouse gas production

Purpose

We investigate the potential of increasing temperature on CH₄ and CO₂ (C gas) production in order to predict the C gas production in tropical freshwater ecosystems. We explored seasonal variation of C gas production by simulations of the anaerobic decomposition of Utricularia breviscapa within the sediment of a tropical aquatic system, using a bioassay response, within the context of carbon cycling.

Materials and methods

We incubated U. breviscapa detritus in lake water from Óleo Lagoon, Brazil, and measured rates of CO₂ and CH₄ production over 138 days at four distinct temperatures simulating seasonal conditions of the lagoon from which the plant was collected. Periodically, subsamples of gases contained in the headspace of the decomposition chambers were collected, and the concentrations of CO₂ and CH₄ were quantified by gas chromatography.

Results and discussion

Methane production was limited at temperatures below 20 °C. Higher temperatures favored formation of CO₂, while CH₄ was a secondary product. The CO₂ from the anaerobic metabolism of the sediment was the dominant final product.

Conclusions

Based on the responses from the bioassays simulating the anaerobic decomposition of the prevalent U. breviscapa, we conclude that in the cooler (<20 °C) season (June and July), CH₄ production is limited, and that year-round dominant mineralization product is CO₂. Our warmer incubations (i.e., >20 °C temperatures) indicate that CO₂ and CH₄ productions are both favored during warmer seasons, but CH₄ appears with a delayed response. Within the range of temperatures of this tropical environment, biogenic C gas emissions from anaerobic degradation processes in sediments contribute strongly to the accumulation of C gas through carbon dynamics.     

Impact of sanitary landfill on air quality in Baghdad

Hydrogen sulfide, NH₃ and CH₄ are pollutant gases known to be generated from the fermentation of organic matter in solid waste. This work was conducted in a completed sanitary landfill in Baghdad to investigate the possible effect of gases generated and emitted from this landfill on the ambient air quality of the area. Pollutant gases were monitored twice a week for a 14 mo period using continuous monitoring type instruments. Results indicate that concentrations of H₂S, NH₃, and CH₄ occasionally reach relatively high levels. The air quality of the area is not substantially deteriorated.