基于层次分析法的坦塘垃圾填埋场适宜性评价

垃圾填埋场场址的适宜性评价是生活垃圾填埋场建设和运营的前提和基础。以湖南省永州市坦塘垃圾填埋场为例,在分析研究区的地质与水文地质条件的基础上,确定了填埋场适宜性的影响因素为填埋场规模、运输条件、环境条件、建场条件和地质条件,具体包括填埋场面积及容量、综合路况条件、对地表水体污染的可能性、地形平坦程度以及场地是否处在岩溶区等条件,明确了局部地区岩溶发育是制约其适宜性的主要因素。结合垃圾填埋场的建设情况和相关规范、标准,采用层次分析法对坦塘垃圾填埋场进行适宜性评价。评价结果表明,坦塘垃圾填埋场是一个适宜场地,评价结果与实际情况相符。     

渗滤液污染包气带中铁的形态变化

从渗滤液场龄和包气带岩性两方面出发,研究了新、老渗滤液对亚粘土和细砂包气带环境中Fe的含量及存在形态的影响。结果表明：新、老渗滤液分别能使细砂包气带介质中除残渣态以外Fe的含量增加16.68%或降低13.82%。亚粘土比细砂作为包气带介质更能缓冲渗滤液对介质中Fe的影响程度,其受影响范围在包气带0～20 cm深度处。当亚粘土为介质的包气带被新渗滤液污染后,其表层介质中碳酸盐结合态Fe的含量会增加15倍之多,为缓冲渗滤液Fe的污染做出了巨大贡献,但这部分Fe的存在也是潜在的二次污染源,在环境pH急剧变化的情况下,它可能会引起地下水高铁污染。     

Real-time measurements of landfill atmospheric ammonia using mobile white cell differential optical absorption spectroscopy system and engineering applications

ABSTRACT

The real-time measurement of atmospheric ammonia at municipal solid waste (MSW) landfills and adjacent areas is necessary for landfill management and the health of nearby residence. Continuous, fast, and real-time monitoring of landfill odor gases is a challenge, especially for ammonia. To our knowledge, this was the first study for the characteristics and seasonal variabilities of atmospheric ammonia at a whole landfill using a Mobile White cell Differential Optical Absorption Spectroscopy (MW-DOAS) system, which also simultaneously offers high sensitivity and fast response. Results show that atmospheric ammonia levels at various landfill areas were significantly dependent on the characteristics of areas, such as municipal solid waste-related areas, leachate-related areas, sludge-related areas, and fly ash-related area, the atmospheric ammonia peak or average level at the active leachate pool of the active MSW site was the highest among all areas of the whole landfill, and the ammonia concentrations at the closed MSW landfill sites were low and dependent on the ages. Moreover, it was found that the seasonal variabilities of ammonia concentrations at most of those areas were significantly dependent on the ambient temperature, and ambient temperature variation caused the atmospheric ammonia level at the active leachate pool and active MSW landfill site in the summer survey to raise 3.5 times and 5.58 times than in the winter survey, respectively.

Implications: Continuous, fast, and real-time monitoring ambient ammonia at or nearby a landfill is critical for landfill operators and local EPAs. This study demonstrates that the mobile White cell Differential Optical Absorption Spectroscopy (MW-DOAS) system is an effective tool for real-time monitoring ambient ammonia of a whole landfill. The results in this article provided a guideline to the characteristics and seasonal changes of ambient ammonia at various types of areas of a whole landfill as well as the impact of age to ambient ammonia at the closed landfill areas.     

Air Pollution Directional Risk Assessment for Siting a Landfill

Abstract

Air pollution directional risk (APDR) is an essential factor to be assessed when selecting an appropriate landfill site. Because air pollutants generated from a landfill are diffused and transported by wind in different directions and speeds, areas surrounding the landfill will be subject to different associated risks, depending on their relative position from the landfill. This study assesses potential APDRs imposed from a candidate landfill site on its adjacent areas on the basis of the pollutant distribution simulated by a dispersion model, wind directions and speeds from meteorological monitoring data, and population density. A pollutant distribution map layer was created using a geographic information system and layered onto a population density map to obtain an APDR map layer. The risk map layer was then used in this study to evaluate the suitability of a candidate site for placing a landfill. The efficacy of the proposed procedure was demonstrated for a siting problem in central Taiwan, Republic of China.     

Pilot monitoring study of ibuprofen in surface waters of north of Portugal

Ibuprofen is amongst the most worldwide consumed pharmaceuticals. The present work presents the first data in the occurrence of ibuprofen in Portuguese surface waters, focusing in the north area of the country, which is one of the most densely populated areas of Portugal. Analysis of ibuprofen is based on pre-concentration of the analyte with solid phase extraction and subsequent determination with liquid chromatography coupled to fluorescence detection. A total of 42 water samples, including surface waters, landfill leachates, Wastewater Treatment Plant (WWTP), and hospital effluents, were analyzed in order to evaluate the occurrence of ibuprofen in the north of Portugal. In general, the highest concentrations were found in the river mouths and in the estuarine zone. The maximum concentrations found were 48,720 ng?L^?1 in the landfill leachate, 3,868 ng?L^?1 in hospital effluent, 616 ng?L^?1 in WWTP effluent, and 723 ng?L^?1 in surface waters (Lima river). Environmental risk assessment was evaluated and at the measured concentrations only landfill leachates reveal potential ecotoxicological risk for aquatic organisms. Owing to a high consumption rate of ibuprofen among Portuguese population, as prescribed and non-prescribed medicine, the importance of hospitals, WWTPs, and landfills as sources of entrance of pharmaceuticals in the environment was pointed out. Landfill leachates showed the highest contribution for ibuprofen mass loading into surface waters. On the basis of our findings, more studies are needed as an attempt to assess more vulnerable areas.     

A study on the carrying capacity of the available habitat for the Rhinopithecus bieti population at Mt. Laojun in Yunnan, China

Background, aim, and scope  The Yunnan snub-nosed monkey is one of the most endangered primates in the world. It is experiencing a range of ongoing threats and the persisting effects of past disturbances. The prospects for this species are not very optimistic because habitat corridors are severely damaged by logging, grazing, and mining. Each group of the monkeys in different areas is facing a unique variety of threats. Based on genetic analysis, Rhinopithecus bieti should be separated into three management units for conservation, of which the Mt. Laojun management unit involves the most endangered primates. Despite the fact that the vegetation on Mt. Laojun is in a relatively pristine state, only two groups of monkeys, of a total of fewer than 300, survive in the area. With this paper, we aimed to address the capacity of the monkeys’ habitat at the study site and the possible reasons for the small populations. Materials and methods  Rapid ecological assessment based on a SPOT 5 image and field survey was used to simulate the vegetation of the whole area based on reference ecological factors of the GIS system. The vegetation map of the site was thus derived from this simulation. Based on the previous studies, the three vegetation types were identified as the suitable habitat of the monkeys. The confusion matrix-based field GPS points were applied to analyze the precision of the habitat map. Based on the map of suitable habitat of the monkeys, the utilization of the habitat and the carrying capacity were analyzed in the GIS. Results  The confusion matrix-based field GPS points were applied to the habitat analysis process, and it was found that the habitat map was 81.3% precise. Then, with the current habitat map, we found that the mixed forest currently used by the monkeys is only a very small fraction (2.65%) of the overall potential habitat of the population, while the dark conifer forest is 4.09%. Discussion  Poaching is the greatest short-term threat to this species, particularly in the southern range where local residents have a strong tradition of hunting. Quite a few individual monkeys are still trapped accidentally due to the high density of traps. These problems are hard to mitigate because it is difficult to enforce laws due to the extremely rugged terrain. Conclusions  The results show that there is a great ecological capacity of the area for the monkey’s survival and a great potential for an expansion of the monkey population at the site. Based on the current population and its geographical range, it can be estimated that the suitable habitat area defined by this study can support more monkeys, about many times the current population. Thus, at least in the Mt. Laojun Area, poaching pressure is the main factor to be responsible for the low density of Yunnan snub-nosed monkeys instead of habitat alteration. Recommendations and perspectives  Based on these results, some suggestions relating to conservation can be made: Focus conservation efforts on the current distribution area of the monkeys and create a 20 km buffer zone; design a long-term plan for the suitable habitat outside the buffer zone to set up a wildlife corridor in the long run; establish an association for the local hunters exploiting, their knowledge on the animals to promote monkey conservation and stop poaching. Also, the map derived from the study helps managers to allocate conservation resources more efficiently and enhances the overall outcomes of conservation measures.     

A comprehensive study on landfill site selection for Kolkata City,India

Kolkata is one of the four major metropolitan cities in India and the capital city of the state of West Bengal. With an area of 187.33 km² and a population of about 10 million (including a floating population of about 6 million), the city generates about 3500 Metric Ton (MT) of solid waste per day. Currently, Kolkata Municipal Corporation (KMC) disposes its waste at Dhapa (21.47 ha), where the disposal rate exceeds 3000 MT/day, and at Garden Reach (3.52 ha), where the disposal rate is 100 MT/day. Considering the exhaustion of Dhapa land space, city planners are urgently searching for an alternate disposal ground. National Environmental Engineering Research Institute (NEERI), under the sponsorship of Central Pollution Control Board (CPCB), has brought out literature developing the site selection criteria for municipal solid waste disposal ground to suit Indian conditions. The developed criteria encompass environmental conditions, accessibility, geological and hydrogeological conditions, and ecological and societal effects. This paper attempts to locate the most suitable site for disposal of KMC area solid waste using the multicriterion decision analysis as stipulated in CPCB 2003 guidelines and the overlay analysis of geographic information system (GIS).

Implications:The paper is based on landfill site selection for dumping of solid waste generated within Kolkata Municipal Corporation (KMC) area. The methodology uses GIS/remote sensing, Site Sensitivity Index (an offshoot of pairwise comparison technique developed in CPCB 2003 guidelines, Government of India), and the Delphi technique. Dhapa landfill site, where solid waste of KMC area is currently being disposed, is exhausted; the authors of this article thus found it relevant to carry out a research on the selection of an alternative landfill site. The study undertaken was comprehensive, yet presented in a lucid way so that policymakers will find easy to comprehend.     

Simulation of the Environmental Impact of an Airport on the Surrounding Air Quality

It is the purpose of this study to demonstrate the procedure involved in simulating those average and maximum pollutant concentrations at or around an airport which fall under the control of the Clean Air Act. The information is useful, when planning new or expanding existing airports, when estimating the impact of airports on the surrounding air quality, and when assessing the effectiveness of control procedures. Simulation of airport air quality requires the accurate assessment of the temporal and spatial emission patterns. This involves the tabulation of air traffic density by type and engine, make and model of aircraft, and engine mode number; the use of fuel by different aircraft; the pollutant emission rates by engine model and operational mode; the allocation of emission rates to the respective runways, turn-off points, taxi-ways, and parking areas, and the time each aircraft spent in the different operational modes. The resulting emission pattern for the Honolulu International Airport reflects scheduled and unscheduled commercial and military jet and piston aircraft and nonaircraft operations. Using this and the appropriate meteorological information average and maximum surface concentrations were calculated and compared with local ambient air quality standards. The calculation of concentrations is based on a newly developed diffusion model incorporating harmonic mean wind speeds for every degree of wind direction as determined by a Parzen maximum likelihood interpolation technique, and the assumption of log-normal concentration distributions. It is shown that for some pollutants the air quality standards are substantially exceeded, and it is concluded that airports may have a considerable adverse impact on their surrounding air quality.     

城市生活垃圾卫生填埋场恶臭的防治技术进展

恶臭污染已成为垃圾处理和处置过程中的严重公害。在分析中,介绍了填埋场各区域恶臭的控制措施,综述了卫生填埋场恶臭的常规防治技术,重点讨论了生物技术在填埋场脱臭中的应用,这些防治技术对各类环境卫生设施,如垃圾收集站、中转站、焚烧场、堆肥厂及粪便处理厂的臭气治理均有借鉴意义。     

Odorous emission reduction from a waste landfill with an optimal protection system based on fuzzy logic

Effective landfill management and operation require an accurate evaluation of the occurrence and extent of odour emission events, which are among the main causes of resident complaints and concerns, in particular in densely urbanised areas. This paper proposes a fuzzy optimal protection system (FOPS) based on fuzzy logic to manage odour production from a municipal solid waste (MSW) landfill. The case study is a MSW landfill in an old quarry site located 6 km north-west of Naples city centre (Italy). The aim is to reduce the odour nuisance in the area surrounding the landfill where there are several sensitive receptors. FOPS is based on logical relationships between local atmospheric dynamics, number and intensity of odour pollution events detected by certain fixed receptors and odour emission rate via an optimal fuzzy approach. Such system allows to start, in real time, established mitigation actions required to further reduce the odorous emissions from the landfill itself (e.g. spraying of perfumed substances and activation of extraction wells), especially when weather conditions might not be favourable and cause by causing a higher odour perception. The fuzzy system was coupled with the air pollutant transport software CALPUFF to simulate the odour dispersion in the considered area taking into account both different odour emission rates and local weather conditions. FOPS results show that this approach can be very useful as, by measuring the odour concentrations, a significant reduction of the odour exceedances over the thresholds fixed, to minimise the olfactory harassment, was observed in the whole area studied.

     

Soybean production and conversion of tropical forest in the Brazilian Amazon: the case of Vilhena, Rondônia

The recent rise in Brazilian soybean production has generated concern among the environmental community and some authors that natural tropical environments of the Amazon Basin are being converted to soybean fields. Proponents of soybean production counter that soybeans represent a viable agricultural commodity for the region; environmental concern is unwarranted, because new soybean fields are replacing already deforested or otherwise transformed lands. Both arguments have been made without comprehensive study and measure of land-use/land-cover (LULC) in areas undergoing expansion of soybean production. This case study, conducted in the municipality of Vilhena, Rond?nia, Brazil, in the southwestern Amazon Basin, uses remote sensing to evaluate the LULC accompanying this municipality's large growth in soybean production from 1996 to 2001. Forests are being converted for soybean production, but most of the production increase appears attributable to slight expansion of already existing fields, conversion of already deforested land, and higher yields.     

Demarcating coastal vegetation buffers with multicriteria evaluation and GIS at Saldanha Bay, South Africa

The Saldanha-Langebaan coastal zone forms an integral part of the South African coastal resource base. As elsewhere in the world, an acute need exists to balance development and economic growth and conservation in the coastal zone as an exploitable resource frontier area. Vegetated buffers and greenways are conservation concepts that have been used with great success in such conservation efforts. They are applied in the study area through the use of a Geographic Information System (GIS) as spatial decision-support system to legitimize the demarcation of a vegetated buffer zone. The method of multicriteria evaluation, as applied here, incorporates public decision-making in constructing an objective model for buffer zone demarcation. Representatives from interested and affected parties participated in model construction and calibration, resulting in the spatial delimitation of a multifunctional vegetated buffer. It conforms to a range of functional criteria and can serve as an environmental element in coastal conservation planning frameworks.     

Application of back-trajectory techniques to the delimitation of urban clean air zones

Following a request by environmental authorities in New Zealand, atmospheric modelling has been applied to delimitation of clean air zones for urban areas. This approach involved the integration of a kinematic trajectory model with an atmospheric mesoscale model to identify the spatial extent of the catchment of air affecting air pollution concentrations in Christchurch on nights of high air pollution. The Regional Atmospheric Modelling System (RAMS) was configured for the region and idealised simulations performed to obtain predicted wind fields for synoptic situations typical of winter smog events. The predicted surface wind fields on two grids, with horizontal resolutions of 1.5 and 0.5 km, respectively, were then used to derive back-trajectories from the late evening peak of pollution over the central city (around 2200 NZST) to the time at which people tend to first light their domestic fires (around 1800 NZST). The results indicate that although winds are often light, the air tends to travel from a significant distance outside the city boundary over this time period. In particular, cold air typically travels up to 20 km from the Canterbury Plains to the west into the city during these air pollution events, as well as from small valleys in the Port Hills to the south of the city. This research illustrates the significance of upstream sources of air for providing relatively clean air to the city, and acting as buffer zones. It is, therefore, possible to identify the area around the city to which urban air quality is particularly sensitive. This area could either be designated as a buffer zone, or included within the clean air zone of the city. This technique also provides a useful tool for identifying the role of different components of the local wind field responsible for air pollution dispersion and transport in different parts of the area.     

络合铁法脱除垃圾填埋气中的H2S

建立了以EDTA和柠檬酸为铁盐络合剂的循环脱硫体系,采用络合铁法对垃圾填埋气中的H₂S进行脱硫中试实验,结果表明实验所建立的络合铁脱硫体系运行稳定,脱硫效率高,适合应用于垃圾填埋气中硫化氢脱除。     

A steady state redox zone approach for modeling the transport and degradation of xenobiotic organic compounds from a landfill site

A redox zonation approach is used as a framework for obtaining biodegradation rate constants of xenobiotic compounds in a landfill plume (Grindsted, Denmark). The aquifer is physically heterogeneous in terms of a complex zonation of different geological units close to the landfill and biogeochemically heterogeneous in terms of a specified redox zonation. First-order degradation rates of six organic compounds (benzene, toluene, ethylbenzene, o-xylene, m/p-xylene, and naphthalene) were calculated in the methanogenic/sulfate- and Fe-reducing zones. The numerical simulations show that all compounds are anaerobically biodegraded, but at very different rates. High rates of biodegradation of most of the compounds (except benzene) were found in the Fe-reducing zone. These rates generally agree with previously published rates. Only o-xylene and toluene were significantly biodegraded in the methanogenic/sulfate-reducing environment. All rates in this redox zone are generally much lower than previously published rates.     

Characteristics and management of domestic waste in a rural area of the Tibetan Plateau

In the rural area of the Tibetan Plateau (RATP), the characteristics of domestic waste, people’s environmental awareness, people’s willingness to pay and their influence factors were firstly studied by questionnaires, field samplings and laboratory tests. The results showed that, in the RATP, the generation of domestic waste was 85 g?d-1 per capita and it was mainly composed of plastics, inert waste, kitchen waste, glass and paper. The waste bulk density, moisture content, ash, combustible and low calorific value were 65 kg?m-3, 19.25%, 44.90%, 35.85% and 10,520 kJ?kg-1 respectively. These characteristics are influenced by income sources and geographical position to some extent. Classified collection should be promoted widely on the household and the village basis. Compost, fermentation, landfill, bioreactor landfill and semi-aerobic landfill have been approved as effective techniques to treat domestic waste, except incineration. The distance of 50–800 m between each collection facility and the disposal fee of around $0.8 per month per household are suggested. For suburbs or large population villages, it’s better to treat domestic waste by the centralized way. But for the remote rural areas, a decentralized way is proposed. Significantly, the educational and economic influence should be considered into an effective domestic waste management program.

Implications:?The current situatio n of the environment in the rural areas of the Tibetan Plateau (RATP) was surveyed. There, the generation of organics and moisture of domestic waste were low but ash, recyclables, and combustibles were high. People’s knowledge of domestic waste was absent but their participation in management was strong. Based on the current situation, compost, fermentation, and landfill were effective but incineration was inappropriate. Also, a localized mini landfill for a cluster of villages and or settlements was the best method there.     

Dynamics and mitigation of six pesticides in a “Wet” forest buffer zone

Pesticide pollution is one of the main current threats on water quality. This paper presents the potential and functioning principles of a “Wet” forest buffer zone for reducing concentrations and loads of glyphosate, isoproturon, metazachlor, azoxystrobin, epoxiconazole, and cyproconazole. A tracer injection experiment was conducted in the field in a forest buffer zone at Bray (France). A fine time-scale sampling enabled to illustrate that interactions between pesticides and forest buffer substrates (soil and organic-rich litter layer), had a retarding effect on molecule transfer. Low concentrations were observed for all pesticides at the forest buffer outlet thus demonstrating the efficiency of “Wet” forest buffer zone for pesticide dissipation. Pesticide masses injected in the forest buffer inlet directly determined concentration peaks observed at the outlet. Rapid and partially reversible adsorption was likely the major process affecting pesticide transfer for short retention times (a few hours to a few days). Remobilization of metazachlor, isoproturon, desmethylisoproturon, and AMPA was observed when non-contaminated water flows passed through the forest buffer. Our data suggest that pesticide sorption properties alone could not explain the complex reaction mechanisms that affected pesticide transfer in the forest buffer. Nevertheless, the thick layer of organic matter litter on the top of the forest soil was a key parameter, which enhanced partially reversible sorption of pesticide, thus retarded their transfer, decreased concentration peaks, and likely increased degradation of the pesticides. Consequently, to limit pesticide pollution transported by surface water, the use of already existing forest areas as buffer zones should be equally considered as the most commonly implemented grass buffer strips.     

Non-controlled biogenic emissions to the atmosphere from Lazareto landfill, Tenerife, Canary Islands

GOAL, SCOPE AND BACKGROUND: [corrected] Historically, landfills have been the simplest form of eliminating urban solid waste with the minimum cost. They have been the most usual method for discarding solid waste. However, landfills are considered authentic biochemical reactors that introduce large amounts of contaminants into the environment in the form of gas and leachates. The dynamics of generation and the movement of gas in landfills depend on the input and output parameters, as well as on the structure of the landfill and the kind of waste. The input parameters include water introduced through natural or artificial processes, the characteristics of the urban solid waste, and the input of atmospheric air. The main output parameters for these biochemical reactors include the gases and the leachates that are potentially pollutants for the environment. Control systems are designed and installed to minimize the impact on the environment. However, these systems are not perfect and a significant amount of landfill gas could be released to the atmosphere through the surface in a diffuse form, also known as Non-controlled emission. In this paper, the results of the Non-controlled biogenic gas emissions from the Lazareto landfill in Tenerife, Canary Islands, are presented. The purpose of this study was to evaluate the concentration of CH4 and CO2 in the soil gas of the landfill cover, the CH4 and CO2 efflux from the surface of the landfill and, finally, to compare these parameters with other similar landfills. In this way, a better understanding of the process that controls biogenic gas emissions in landfills is expected. METHODS: A Non-controlled biogenic gas emission survey of 281 sampling sites was carried out during February and March, 2002. The sampling sites were selected in order to obtain a well-distributed sampling grid. Surface landfill CO2 efflux measurements were carried out at each sampling site on the surface landfill together with soil gas collection and ground temperatures at a depth of 30-40 cm.The CH4 efflux was computed from CO2 efflux and from the ratio CH4/CO2 in the soil gas. Soil gas samples were collected at a depth of 30-40 cm using a metallic probe and 20 cc hypodermic syringes, and later stored in evacuated 10 cc vacutainers for laboratory analysis of bulk composition. The gas sample was introduced in a vacutainer filled with deionized water and displacing the water until the vacutainer was filled with the gas sample in order to avoid air contamination from entering. The surface landfill temperature of the landfill was measured at a depth of 40 cm using a digital thermometer type OMEGA 871A. Landfill gases, CO2 and CH4, were analyzed within 24 hours using a double channel VARIAN micro-GC QUAD CP-2002P, with a 10 meter PORAPLOT-Q column, a TCD detector, and He as a carrier gas. The analysis temperature was 40 degrees C and the injection time was 10 msec. Surface landfill CO2 efflux measurements were performed using a portable NDIR spectrophotometer Licor-800 according to the accumulation chamber method (Chiodini et al. 1996). The data treatment, aimed at drawing the flux map and computing the total gas output, was based on the application of stochastic simulation algorithms provided by the GSLIB program (Deutsch and Journel 1998). RESULTS: Diffuse CH4 and CO2 efflux values range from negligible values up to 7,148 and 30,573 g m(-2) d(-1), respectively. The spatial distribution of the concentration and efflux of CO2, CH4 and soil temperature, show three areas of maximum activity in the landfill, suggesting a non-uniform pattern of diffuse degassing. This correlation between high emissions and concentration of CO2, CH4 and soil temperatures suggests that the areas of higher microbial activity and exothermic reactions are releasing CO2 and CH4 to the atmosphere from the landfill. Taking into consideration the spatial distribution of the CO2 and CH4 efflux values as well as the extension of the landfill, the Non-controlled emission of CO2 and CH4 to the atmosphere by the Lazareto's landfill are of 167 +/- 13.3 and 16 +/- 2.5 t d(-1), respectively. DISCUSSION: The patterns of gas flow within the landfill seem to be affected by boundary materials at the sides. The basalt layers have a low permeability and the gas flow in these areas is extensive. In this area, where a basalt layer does not exist, the flow gas diffuses toward the sea and the flux emissions at the landfill surface are lower. This behavior reflects the possible dissolution of gases into water and the deflection of gases towards the surface at the basalt boundary. The proximity to the sea, the installation of a palm tree garden and, as a result, the contribution of water coming from the watering of this garden has reactivated the system. The introduction of sea water into the landfill and the type of boundary could be defining the superficial gas discharges. CONCLUSIONS: Results from this study indicate that the spatial distribution of Non-controlled emission of CO2 and CH4 at the Lazareto's landfill shows a non-uniform pattern of diffuse degassing. The northeast, central and northwest areas of the Lazareto's landfill are the three areas of high emissions and concentration of CO2 and CH4, and high temperatures. The correlation between high emissions and the concentration of CO2, CH4, and the high temperatures suggest that the areas of higher microbial activity and exothermic reactions are releasing more CO2 and CH4 to the atmosphere from the landfill. A high concentration of CO2 is probably due to the presence of methanotrophic bacteria in the soil atmosphere of the landfill. Patterns of gas flow within the landfill seem to be affected by boundary materials (basalt layers) of low permeability, and side boundaries of the flux emissions at the surface are higher. At the sides of seawater and sediment boundaries, flux emissions at the landfill surface are lower. This behavior reflects a possible dissolution of gases into the water and the deflection of gases towards the surface at the basalt boundary. With this study, we can compare the data obtained in this landfill with other landfills and observe the different levels of emission. The proximity to the sea and the installation of the palm tree garden palms and, as a result, the contribution of water coming from the watering of this garden has reactivated the system. Many landfills worldwide located in similar settings could experience similar gas production processes. RECOMMENDATIONS AND PERSPECTIVES: The need for investigating and monitoring sea water and sediment quality in these landfills is advisable. Concentrations and fluxes of contaminants and their impact in the area should be assessed. With this study we can compare the data obtained in these landfills with other landfills and observe the different levels of emission.     

垃圾填埋场加速稳定化表征指标的相关性分析

加速稳定化表征指标是生物反应器填埋技术评价的重要内容。通过垃圾填埋室内模拟实验,研究不同运行工况下垃圾挥发性固体(VS)、生物可降解物(BDM)、纤维素(C)和纤维素/木质素(C/L)等组分指标的动态变化规律及其对加速稳定化进程的指示作用,进而探寻各指标之间的相关性,进一步筛选确定垃圾填埋场加速稳定化进程的核心表征指标。结果表明,垃圾组分VS、BDM、C和C/L的衰减符合一级反应动力学,其动态变化能够较为灵敏地指示渗滤液回灌和通风供氧对垃圾稳定化的显著加速作用,可作为垃圾填埋场加速稳定化进程的表征指标。VS、BDM、C和C/L相互之间具有良好的正线性相关性。BDM和C/L适宜作为垃圾填埋场加速稳定化进程的核心表征指标。     

83rd Annual Meeting & Exhibition

Abstract

The estimation of odor production and dispersion from landfill sites is a very complicated task because of the different chemical species that exist in biogas. To site a new landfill, it is necessary to know the distance that odors can travel around the landfill under atmospheric conditions that increase the concentration of pollutants. Although CH₄ is an odorless gas, it can be used as an index to determine the dispersion of low-reactivity odorous species around a landfill site. Methane production rates, estimated by biogas production models, were used by an air dispersion model to determine the spatial distribution of CH₄ around landfill sites. By utilizing dispersion models under extreme atmospheric conditions, a maximum CH₄ concentration around the landfills was determined. Based on the ratio between CH₄ and odorous chemical species, the spatial distribution of the concentration of an odorous species was determined for those species with low reactivity in the atmosphere. For odorous species with high reactivity in the atmosphere, a dispersion-reaction model must be used. In this way, the acceptable distance between new landfills and residential areas can be determined. The proposed methodology could be used as a design tool for those who are interested in landfill siting.