Chemical characterization of emissions from a municipal solid waste treatment plant

Gaseous emissions are an important problem in municipal solid waste (MSW) treatment plants. The sources points of emissions considered in the present work are: fresh compost, mature compost, landfill leaks and leachate ponds. Hydrogen sulphide, ammonia and volatile organic compounds (VOCs) were analysed in the emissions from these sources. Hydrogen sulphide and ammonia were important contributors to the total emission volume. Landfill leaks are significant source points of emissions of H₂S; the average concentration of H₂S in biogas from the landfill leaks is around 1700 ppmv. The fresh composting site was also an important contributor of H₂S to the total emission volume; its concentration varied between 3.2 and 1.7 ppmv and a decrease with time was observed. The mature composting site showed a reduction of H₂S concentration (<0.1 ppmv). Leachate pond showed a low concentration of H₂S (in order of ppbv). Regarding NH₃, composting sites and landfill leaks are notable source points of emissions (composting sites varied around 30–600 ppmv; biogas from landfill leaks varied from 160 to 640 ppmv).Regarding VOCs, the main compounds were: limonene, p-cymene, pinene, cyclohexane, reaching concentrations around 0.2–4.3 ppmv.H₂S/NH₃, limonene/p-cymene, limonene/cyclohexane ratios can be useful for analysing and identifying the emission sources.     

Migration of inorganic ions from the leachate of the Rio das Ostras landfill: A comparison of three different configurations of protective barriers

Batch tests and diffusion tests were performed to analyze the efficiency of a protective barrier in a landfill consisting of compacted soil with 10% bentonite compared to the results obtained for only compacted soil and for compacted soil covered with a 1-mm-thick HDPE geomembrane; the soil and leachate were collected from the Rio das Ostras Landfill in Rio de Janeiro, Brazil. The diffusion tests were performed for periods of 3, 10 and 60 days. After the test period, the soil pore water was analyzed and the profiles for chloride, potassium and ammonium were determined along a 6-cm soil depth. The results of the batch tests performed to define sorption parameters were used to adjust the profiles obtained in the diffusion cell experiment by applying an ion transfer model between the interstitial solution and the soil particles. The MPHMTP model (Multi Phase Heat and Mass Transfer Program), which is based upon the solution of the transport equations of the ionic contaminants, was used to solve the inverse problem of simultaneously determining the effective diffusion coefficients. The results of the experimental tests and of the model simulation confirmed that the compacted soil with 10% bentonite was moderately efficient in the retention of chloride, potassium and ammonium ions compared to the configurations of compacted soil with a geomembrane and compacted soil alone, representing a solution that is technically feasible and requires potentially lower costs for implementation in landfills.     

Longitudinal data analysis in support of functional stability concepts for leachate management at closed municipal landfills

Landfill functional stability provides a target that supports no environmental threat at the relevant point of exposure in the absence of active control systems. With respect to leachate management, this study investigates “gateway” indicators for functional stability in terms of the predictability of leachate characteristics, and thus potential threat to water quality posed by leachate emissions. Historical studies conducted on changes in municipal solid waste (MSW) leachate concentrations over time (longitudinal analysis) have concentrated on indicator compounds, primarily chemical oxygen demand (COD) and biochemical oxygen demand (BOD). However, validation of these studies using an expanded database and larger constituent sets has not been performed. This study evaluated leachate data using a mixed-effects regression model to determine the extent to which leachate constituent degradation can be predicted based on waste age or operational practices. The final dataset analyzed consisted of a total of 1402 samples from 101 MSW landfills. Results from the study indicated that all leachate constituents exhibit a decreasing trend with time in the post-closure period, with 16 of the 25 target analytes and aggregate classes exhibiting a statistically significant trend consistent with well-studied indicators such as BOD. Decreasing trends in BOD concentration after landfill closure can thus be considered representative of trends for many leachate constituents of concern.     

Field investigation of the quality of fresh and aged leachates from selected landfills receiving e-waste in an arid climate

The management of electronic waste (e-waste) is a serious problem worldwide and much of it is landfilled. A survey of four selected landfills in an arid region of South Australia was conducted to determine the proportion of e-waste in municipal waste and the properties of each landfill site. Leachate and groundwater samples were collected upgradient and downgradient of the landfills for analysis of polybrominated diphenyl ethers (PBDEs) and 14 metals and metalloids, including Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, V and Zn. Our data demonstrate that the selected landfills in South Australia continue to receive municipal waste containing in excess of 6%, or 25,000 tonnes per year, of e-waste. The leachates and groundwater collected from the landfills contained significantly elevated concentrations of Pb with the highest concentration in groundwater of 38 μg/l, almost four times higher than the Australian drinking water guideline of 10 μg/l. The presence of PBDEs was detected in both leachate and groundwater samples. Total PBDEs values of 2.13–59.75 ng/l in leachate samples were 10 times higher than in groundwater samples, which recorded a range of 0.41–6.53 ng/l at all sites. Moreover, the concentrations of metals and metalloids in sampled groundwater contained elevated levels of Al, As, Fe, Ni and Pb that exceeded Australian drinking water guideline values. For these reasons potential leaching of these contaminants is of concern and while difficult to attribute elevated contaminant levels to e-waste, we do not recommend continued disposal of e-waste in old landfills that were not originally designed to contain leachates. The survey also revealed temporal variation in the electrical conductivity and concentrations of As, Cd and Pb present in leachates of landfills in arid Mediterranean climates. These results are consistent with the marked variations in rainfall patterns observed for such climates. The solute concentration (EC and other ions including As, Cd and Pb) declines in the leachates during wet winter months (June to September), in contrast to tropical countries where such changes are observed during wet summer months.     

Using liquid waste streams as the moisture source during the hydrothermal carbonization of municipal solid wastes

Hydrothermal carbonization (HTC) is a thermal conversion process that can be an environmentally beneficial approach for the conversion of municipal solid wastes to value-added products. The influence of using activated sludge and landfill leachate as initial moisture sources during the carbonization of paper, food waste and yard waste over time at 250 °C was evaluated. Results from batch experiments indicate that the use of activated sludge and landfill leachate are acceptable alternative supplemental liquid sources, ultimately imparting minimal impact on carbonization product characteristics and yields. Regression results indicate that the initial carbon content of the feedstock is more influential than any of the characteristics of the initial liquid source and is statistically significant when describing the relationship associated with all evaluated carbonization products. Initial liquid-phase characteristics are only statistically significant when describing the solids energy content and the mass of carbon in the gas-phase. The use of these alternative liquid sources has the potential to greatly increase the sustainability of the carbonization process. A life cycle assessment is required to quantify the benefits associated with using these alternative liquid sources.     

灰场包气带环境影响预测方法研究——以新疆某电厂灰场为例

灰场在防渗不当或事故工况下,淋滤液的渗漏可能会对灰场包气带产生影响。以新疆某火电厂灰场的淋滤液渗漏情景为例,介绍了淋滤液渗漏对包气带影响的3种预测方法并进行对比分析。结果表明,两类解析法计算误差较大且存在各自适用条件,应优先采用数值法进行定量化预测。     

关于垃圾填埋场渗滤液处理工艺的探讨

渗滤液的处理一直是生活垃圾填埋场存在的一大问题,尤其是新标准执行以来,对渗滤液的排放提出了更加严格的要求,因此处理工艺的选择成为达标排放的关键问题,本文中的“厌氧＋生化＋超滤＋纳滤＋反渗透”组合型渗滤液处理工艺能够确保污染物达标排放,并同时能满足处理后废水综合利用的要求。     

垃圾渗滤液的深度处理实践

垃圾渗滤液的无害化处理是污水处理的难点,国内目前垃圾焚烧厂渗滤液较多采用三级排放标准,而后进入城市污水处理站进一步深化处理。随国家环保排放要求的日趋严格,研究在原有设施基础上进行深度处理改造,是势在必行的。本文通过介绍太仓垃圾焚烧发电项目渗滤液的深度处理改造实践,对行业内其他垃圾焚烧厂提高排放标准具有借鉴意义。     

卫生填埋场水平防渗系统各结构单元设计深度探讨

结合《生活垃圾卫生填埋场防渗系统工程技术规范》（CJJ113－2007）和《生活垃圾填埋场污染控制标准》（GB16889－2008）,在此基础上进一步探讨卫生填埋场水平防渗系统各结构单元的组成详细设计。     

The presence and partitioning behavior of flame retardants in waste, leachate, and air particles from Norwegian waste-handling facilities

Flame retardants in commercial products eventually make their way into the waste stream.Herein the presence of flame retardants in Norwegian landfills, incineration facilities and recycling sorting/defragmenting facilities is investigated. These facilities handled waste electrical and electronic equipment(WEEE), vehicles, digestate, glass, combustibles, bottom ash and fly ash. The flame retardants considered included polybrominated diphenyl ethers(∑BDE-10) as well as dechlorane plus, polybrominated biphenyls, hexabromobenzene,pentabromotoluene and pentabromoethylbenzene(collectively referred to as ∑FR-7). Plastic,WEEE and vehicles contained the largest amount of flame retardants(∑BDE-10: 45,000–210,000 μg/kg; ∑FR-7: 300–13,000 μg/kg). It was hypothesized leachate and air concentrations from facilities that sort/defragment WEEE and vehicles would be the highest. This was supported for total air phase concentrations(∑BDE-10: 9000–195,000 pg/m~3 WEEE/vehicle facilities, 80–900 pg/m~3 in incineration/sorting and landfill sites), but not for water leachate concentrations(e.g., ∑BDE-10: 15–3500 ng/L in WEEE/Vehicle facilities and 1–250 ng/L in landfill sites). Landfill leachate exhibited similar concentrations as WEEE/vehicle sorting and defragmenting facility leachate. To better account for concentrations in leachates at the different facilities, waste-water partitioning coefficients, Kwastewere measured(for the first time to our knowledge for flame retardants). WEEE and plastic waste had elevated Kwastecompared to other wastes, likely because flame retardants are directly added to these materials. The results of this study have implications for the development of strategies to reduce exposure and environmental emissions of flame retardants in waste and recycled products through improved waste management practices.