垃圾填埋场区域氨氮污染地下水的修复方案比选

早期建设的简易生活垃圾填埋场的防渗措施不足,易发生渗漏,造成填埋场周围地下水的氨氮浓度升高。文章针对华中地区某垃圾填埋场区域氨氮污染地下水,提出抽取处理加异位生物修复、空气注入加原位生物修复两种修复方案,并采用AHP-TOPSIS(层次分析法-逼近理想排序)方法进行方案的比选。在建立合适的比选指标体系基础上,采用AHP-TOPSIS方法进行综合比选研究。结果表明,空气注入+原位生物修复技术更适合于该区域地下水的修复。TOPSIS方法由于缺乏确定评价指标权重的过程,在层次多元分析中的应用受到限制,而AHP是多层次多因素权重确定的有效工具,将二者结合起来,先由AHP确定指标权重,再运用TOPSIS对备选地下水修复方案进行排序,从而弥补了二者各自的不足。AHP-TOPSIS方法可作为环境工作者进行场地修复方案比选的有效工具。     

Landfill diversion in a decentralized setting: A dynamic assessment of landfill taxes

We analyze the process of landfill diversion and its main determinants, by embedding the dynamics in a frame where economic, geographical and policy variables come into play. In addition to structural and economic drivers, we primarily investigate whether the Italian tax has been effective in supporting landfill diversion. Although the Italian landfill tax dates back to 1996, the oldest in the EU, its effectiveness in terms of landfill diversion has not been assessed yet. The complexity primarily derives from the decentralized regional implementation and the absence of a full coherent dataset covering all regions. We merge this new and original data on taxes to an integrated dataset which includes economic, waste and policy variables at regional level over the period 1999–2008. Panel regressions show that the effect of tax is significant, even when taking into account for its possible endogeneity. Regions that have increased such taxes have improved waste disposal performances over time. Landfill taxes are surely not the only instrument policy makers might introduce, but they seem to play a relevant role in the evolution of Italian waste disposal performances.     

Factors affecting the concentration of bisphenol A in leachates from solid waste disposal sites and its fate in treatment processes

 The concentrations of bisphenol A (BPA) contained in landfill leachates from solid waste disposal sites were measured. The concentrations of BPA contained in leachates from industrial waste sites were in the range below the detection limit to 2800 μg/l, while those from municipal sites were in the range 26–8400 μg/l. The leachates from ash-rich sites contained relatively lower concentrations of BPA compared with organic-rich leachates. It is suggested that BPA concentration increases with time after the completion of reclamation in the case of ash-rich sites, whereas the concentration of BPA decreases with time in the case of organic-rich sites. A 7-year survey on a site in Japan showed neither a decrease nor an increase in the concentration of BPA during on-going reclamation. A leachate from a site in the Philippines contained high concentrations of BPA. A slight positive correlation was found between BPA concentrations and total organic carbon (TOC). A major portion of the BPA in leachates was found in dissolved and organic unassociated fractions, which cannot be precipitated by coagulation. More than 99.9% of the BPA contained in raw leachates was removed by a conventional series of treatment processes consisting of biological treatment, coagulation, sedimentation, sand filtration, and activated carbon adsorption. Received: May 29, 2002 / Accepted: October 17, 2002     

关于城市生活垃圾填埋场填埋气体的产气影响因素探讨

在总结城市生活垃圾产气的特点的基础上．通过对杭州市天子岭垃圾填埋场内不同条件下的多处生活垃圾堆体所产生的填埋气体进行测量,找寻填埋气体的产气影响因素,从而找到了合适的管理与应用方法。     

垃圾填埋场渗滤液处理技术及示范工程研究

对我国垃圾填埋场渗滤液的处理现状进行阐述和分析：以膜生物反应器（MBR）＋纳滤（NF）处理技术为例,选取常州夹山垃圾填埋场渗滤液处理工程作为示范点．重点介绍该处理技术的实际工程远行情况,示范工程渗滤液出水水质达到GB 16889—1997《生活垃圾填埋污染控制标准》的一级标准,运行费用（含折旧）为19．55元／m^3,具有良好的技术经济优势和推广价值。     

微波法与电热板消解法前处理对垃圾渗滤液重金属含量测定效果的应用比较

为准确有效地测定南充市垃圾渗滤液中多种重金属的含量,选取最适合垃圾渗滤液重金属测定的消解方法,分别采用电热板和微波消解两种方法对垃圾渗滤液进行了前处理,并测定了其中部分重金属的含量。测定结果表明,采用电热板和微波消解两种前处理方法,均能较为准确地测定垃圾渗滤液中的铜、锌等7种重金属元素,但从样品损失率以及准确度来看,微波消解时样品始终处于密闭体系,损失率低,样品的测定值准确性更高,可信度更强,因此在垃圾渗滤液重金属测定时,采用微波消解作为南充市城市生活垃圾渗滤液的前处理方法更具优势。     

Algal purification of pretreated landfill Leachate

The efficiency of microalgae in removing various pollutants in landfill leachate after pretreatment by free stripping or air stripping was tested by a laboratory batch system. The results showed that Chlorella pyrenoidosa and Scenedesmus sp. had similar removal efficiencies with regard to ammoniacal‐nitrogen, oxidized‐nitrogen, orthophosphate and chemical oxygen demand (COD). The COD removal by algal treatment was better in Junk Bay (JB) leachate than in Gin Drinkers’ Bay (GDB) leachate (14–21% and 0.4–7% respectively). No significant difference (P > 0.05) was found in removing other nutrients including ammoniacal‐nitrogen, oxidized‐nitrogen and orthophosphate between leachate from the two landfills, regardless of the pretreatment used. The removal efficiencies of ammoniacal‐nitrogen and phosphorus were found to be higher in air‐stripped leachate than in free‐stripped one. Removal of ammoniacal‐nitrogen and phosphorus in air‐stripped leachate was 30% and 87% respectively. Poor removal of ammoniacal‐nitrogen was probably due to a deficiency in phosphorus (high N : P ratio) for algal growth in leachate. The two‐stage leachate treatment (ammonia stripping followed by algal purification) resulted in overall reduction of COD (38–51%), ammoniacal‐nitrogen (72–96%) and orthophosphate (79–96%).     

Modeling of perched leachate zone formation in municipal solid waste landfills

The paper presents a 1D mathematical model for the simulation of the percolation fluxes throughout a landfill for municipal solid waste (MSW). Specifically, the model was based on mass balance equations, that enable simulation of the formation of perched leachate zones in a landfill for MSW. The model considers the landfill divided in several layers evaluating the inflow to and outflow from each layer as well as the continuous moisture distribution. The infiltration flow was evaluated by means of the Darcy’s law for an unsaturated porous medium, while the moisture distribution evaluation has been carried out on the basis of the theory of the vertically distributed unsaturated flow. The solution of the model has been obtained by means of the finite difference method. The model has been applied to a semi-idealized landfill located in Palermo landfill (Bellolampo). Specifically, field measurements were conducted to determine the relationship between waste density and applied vertical strain. This relationship was then used to relate vertical strain to waste porosity. The inflow rate to the system was simulated via a synthetic hyetograph whose characteristics have been identified in a previous hydrologic study.Three simulations, each with a different initial moisture content, were conducted. The model results showed a different response of the landfill in terms both of flow rates throughout the landfill and moisture profile. Indeed, the initial moisture content drastically influenced not only the formation of perched leachate zones but also their extension. The model can be a useful tool in predicting potential for the formation of perched leachate zones.     

Fluorescence excitation-emission matrix combined with regional integration analysis to characterize the composition and transformation of humic and fulvic acids from landfill at different stabilization stages

Fluorescence excitation-emission matrix spectroscopy (EEMs) combined with fluorescence regional integration (FRI) analysis was used to investigate the composition and transformation of humic acid (HA) and fulvic acid (FA) from landfill. The EEMs of HAs at different landfill ages were characterized by two typical fluorescence chromophores with Ex/Em pairs at Ex = 420-470 nm/Em = 490-530 nm and Ex = 345-375 nm/Em = 450-465 nm. EEMs of FA were featured by other two distinctly different fluorophores with Ex/Em pairs at Ex = 315-335 nm/Em = 420-440 nm and Ex = 255-275 nm/Em = 425-455 nm. The results show that HA extracted from the refuse disposed in the year of 1989 was formed by connecting small-condensed aromatic structures with protein-like chains. Compared with HA extracted from the refuse disposed in the year of 1992, HA extracted from the refuse of 1996 had a higher fluorescence intensity and lower r_(B,A) (the ratio of the fluorescence intensities of peak B and peak A) value. It contained low molar mass components, low aromatic condensation degree, and more easily oxidized substituents. This indicates that the landfill time strongly affects the EEMs characteristics of HA, and that the humification degree of HA increases with the landfill time. A red shift to a longer wavelength region and an increase of fluorescence intensity were observed when the concentration of HA was increased, suggesting that concentration had a great influence on the fluorescence characteristics of HAs. pH (2-12) also had significant effects on the fluorescence intensity, although it exerted no effect on the peak position of fluorescence of HA and FA. The results of FRI show that increasing concentration lead to more interactions among various structure components and that small molecular weight units tend to aggregate or be masked into more complicated and larger structures. The pH influence on the fluorescence intensity of HA seems mainly through molecular configuration, while the fluorescence intensity change with pH may be due to various substituents of FA.     

Determination of first-order landfill gas modeling parameters and uncertainties

Using first-order kinetic empirical models to estimate landfill gas (LFG) generation and collection rates is well recognized in the literature. The uncertainty in the estimated LFG generation rates is a major challenge in evaluating performance of LFG collection and LFG to energy facilities. In this investigation, four methods for quantifying first-order LFG generation model parameters, methane generation potential, L₀, and methane generation rate constant, k, were evaluated. It was found that the model is insensitive to the approach taken in quantifying the parameters. However, considering the recognition of using the model in the literature, the optimum method to estimate L₀ and k is to determine L₀ using disposed municipal solid waste composition and laboratory component specific methane potential values. The k value can be selected by model fitting and regression using the first-order model if LFG collection data are available. When such data are not available, k can be selected from technical literature, based on site conditions. For five Florida case-study landfills L₀ varied from 56 to 77 m³ Mg⁻¹, and k varied from 0.04 to 0.13 yr⁻¹ for the traditional landfills and was 0.10 yr⁻¹ for the wet cell. Model predictions of LFG collection rates were on average lower than actual collection. The uncertainty (coefficient of variation) in modeled LFG generation rates varied from ±11% to ±17% while landfills were open, ±9% to ±18% at the end of waste placement, and ±16% to ±203% 50 years after waste placement ended.