垃圾填埋场水力学特性的研究进展

本文对填埋场渗滤液产生和运移的水力学特性的研究成果进行了总结，建立在填埋垃圾均质各向同性假设基础上的渗滤液运移模型不能满足日后生物反应器填埋场渗滤液回灌系统的设计和操作运行需要，基于填埋垃圾非均质各向异性的填埋场水力学特性将是今后研究的重点。     

填埋期模拟准好氧填埋场的渗滤液水质特征

采用室内试验,模拟填埋期回灌型准好氧填埋场垃圾渗滤液水质变化特征。结果显示,新鲜垃圾的定期填入使渗滤波水质产生明显波动,其主要水质指标（COD、NH3-N等）不存在如非填埋期渗滤液水质指标持续下降的变化规律,表明即使对于回灌型准好氧填埋场,当其已填埋垃圾规模较小时,其处理渗滤液的能力和抵御新填入垃圾干扰的能力均是十分有限的。本研究有助于填埋期垃圾渗滤液的合理回灌。     

应用反渗透技术处理垃圾填埋场渗滤液

垃圾填埋场渗滤液属于高浓度氨氮废水,其水量、水质特性变化大,成分复杂,因此较难处理。反渗透分离技术能有效截留垃圾渗滤液中溶解态的有机和无机污染物。采用三级反渗透处理垃圾渗滤液工艺处理后的出水水质,能够满足《生活垃圾填埋污染控制标准》（DB16889-2008）要求,并把渗滤液浓缩液回灌于填埋场。     

北京市垃圾填埋场地下水中砷、汞含量分析

生活垃圾的处置一直以填埋为主,垃圾填埋承载着巨大的环境压力,尤其是垃圾填埋产生的渗滤液会对地下水造成砷、汞污染。为了解北京市生活垃圾填埋场地下水砷、汞污染水平,在北京市5座生活垃圾填埋场布设采样点,采集36个地下水样品,采用氢化物发生-原子荧光法,分析了地下水砷、汞含量特征。结果表明,36个地下水样品砷浓度范围0.41~4.82μg/L,汞浓度范围0.024~0.121μg/L,北京市典型垃圾填埋场地下水样品不存在砷、汞污染问题。     

垃圾填埋场渗滤液对地下水污染的修复技术

在查阅国内外相关文献资料的基础上，综述了垃圾填埋场渗滤液的产生以及对地下水的污染，介绍了垃圾渗滤液污染控制措施，包括顶部覆盖层、垃圾分层填埋、地表入渗水导流等；然后主要介绍了地下水的原位修复技术，包括加药法、地下曝气法、生物修复，等。     

垃圾填埋场渗滤液回灌技术研究

垃圾填埋场会产生大量的垃圾渗滤波,垃圾渗滤液回灌可以利用填埋场内微生物加速分解其中的有机物,同时可以利用回灌控制填埋场的含水量,促进填埋场的稳定.本文概括了渗滤液回灌处理的理论基础、工艺流程,分析了回灌技术的影响因素,并对表面回灌和地下回灌方式进行了比较,指出了推广应用垃圾渗滤液回灌处理技术需要解决的几点问题.     

垃圾处理厂不应成为新的污染源

垃圾填埋场在填埋垃圾以后,会产生高浓度的有机废水,即渗滤液。渗滤液的特点是成分复杂、有机物含量高,垃圾填埋以后渗滤液会连续多年持续产生。因此,为防止对环境的污染,垃圾填埋场必须对渗滤液进行处理,达标后方可排放。     

生活垃圾填埋场渗滤液全量处理模式探索——以四川某填埋场环境整治为例

为解决生活垃圾填埋场渗滤液系统的设计处理能力与实际需求不匹配，以及处理过程产生的膜浓缩液回灌等将引发一系列环境风险和隐患。以四川省某生活垃圾填埋场渗滤液处理改造项目为例，采用“两级A/O+两级Fenton+BAF”处理工艺，实现了渗滤液的“全量化”处理，有效避免了膜浓缩液的产生。运行结果表明，全量处理模式能有效提高渗滤液处理系统的处理效果和能力，保证渗滤液能及时有效排出，避免了渗滤液处理系统的膜液产生和回灌问题，从而缓解和改善填埋场存在的环境风险和隐患。     

城市垃圾填埋场渗滤液处理工艺综述

城市垃圾对环境的影响越来越严重，垃圾填埋导致垃圾渗滤液的大量产生，渗滤液中含有大量的有机物、大量的病菌、病毒、寄生虫等以及一些有毒有害的物质，若渗滤液不加以妥善处理、肆意排放，必将对地下水、地表水构成严重威胁，因此垃圾渗滤液的有效处理就成为一个亟待解决的问题。本文对城市垃圾填埋场渗滤液的处理工艺进行了分析和探讨，介绍了国内外垃圾渗滤液处理的主要技术，包括土地处理法、生物法和物化法，并对电解法处理垃圾渗滤液进行了详细的介绍。     

生物反应器填埋场渗滤液及其处理对策

根据垃圾的降解和稳定机理分析了生物反应器填埋场渗滤液的动态变化规律，并对其处理对策进行了探讨。生物反应器填埋场前期产生的渗滤液可全部回灌，后期再根据实际情况排放处理部分过量的渗滤液。在对渗滤液水量和水质全面直观认识后，再对生物反应器填埋场渗滤液处理工艺进行针对性的选择和设计，并宜采用物化法处理方式。     

GC-MS法测定垃圾填埋场渗滤液中的有机污染物

采用GC-MS联用技术对深圳市两个垃圾填埋场（A和B）渗滤液中的有机污染物进行分析。垃圾场A是简易生活垃圾填埋场，垃圾场B是生活垃圾焚烧底渣填埋场。垃圾场A渗滤液中COD、TOC、NH3-N、NO3^--N等污染指标的浓度比垃圾场B渗滤液高一个数量级。两个垃圾填埋场渗滤液中分别检测出主要有机物72种和57种，其中含有大量难降解有机物，如酚类、胺类、杂环类物质。两个垃圾填埋场渗滤液中有机物组分的相对含量不同，渗滤液A中酚类物质含量最高，渗滤液B中有机物多为长链烷烃。     

The effects of leachate recirculation with supplemental water addition on methane production and waste decomposition in a simulated tropical landfill

In order to increase methane production efficiency, leachate recirculation is applied in landfills to increase moisture content and circulate organic matter back into the landfill cell. In the case of tropical landfills, where high temperature and evaporation occurs, leachate recirculation may not be enough to maintain the moisture content, therefore supplemental water addition into the cell is an option that could help stabilize moisture levels as well as stimulate biological activity. The objectives of this study were to determine the effects of leachate recirculation and supplemental water addition on municipal solid waste decomposition and methane production in three anaerobic digestion reactors. Anaerobic digestion with leachate recirculation and supplemental water addition showed the highest performance in terms of cumulative methane production and the stabilization period time required. It produced an accumulated methane production of 54.87 l/kg dry weight of MSW at an average rate of 0.58 l/kg dry weight/d and reached the stabilization phase on day 180. The leachate recirculation reactor provided 17.04 l/kg dry weight at a rate of 0.14l/kg dry weight/d and reached the stabilization phase on day 290. The control reactor provided 9.02 l/kg dry weight at a rate of 0.10 l/kg dry weight/d, and reached the stabilization phase on day 270. Increasing the organic loading rate (OLR) after the waste had reached the stabilization phase made it possible to increase the methane content of the gas, the methane production rate, and the COD removal. Comparison of the reactors' efficiencies at maximum OLR (5 kgCOD/m(3)/d) in terms of the methane production rate showed that the reactor using leachate recirculation with supplemental water addition still gave the highest performance (1.56 l/kg dry weight/d), whereas the leachate recirculation reactor and the control reactor provided 0.69 l/kg dry weight/d and 0.43 l/kg dry weight/d, respectively. However, when considering methane composition (average 63.09%) and COD removal (average 90.60%), slight differences were found among these three reactors.     

Quality and Quantity of Leachate in Aerobic Pilot-Scale Landfills

In this study, two pilot-scale aerobic landfill reactors with (A1) and without (A2) leachate recirculation are used to obtain detailed information on the quantity and quality of leachate in aerobic landfills. The observed parameters of leachate quality are pH, chloride (Cl⁻), chemical oxygen demand (COD), biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH₃-N), and nitrate (NO₃^–-N). pH values of the leachate increased to 7 after 50 days in reactor A1 and after 70 days in reactor A2. Cl⁻ concentrations increased rapidly to 6100 (A1) and 6900 (A2) mg/L after 80 days, from initial values of 3000 and 2800 mg/L, respectively. COD and BOD values decreased rapidly in the A1 landfill reactor, indicating the rapid oxidation of organic matter. The BOD/COD ratio indicates that leachate recirculation slightly increases the degradation of solid waste in aerobic landfills. NH₃-N concentrations decreased as a result of the nitrification process. Denitrification occurred in parts of the reactors as a result of intermittent aeration; this process causes a decrease in NO₃⁻ concentrations. There is a marked difference between the A1 and A2 reactors in terms of leachate quantity. Recirculated leachate made up 53.3% of the leachate generated from the A1 reactor during the experiment, while leachate quantity decreased by 47.3% with recirculation when compared with the aerobic dry landfill reactor.     

A new system for groundwater contamination hazard rating of landfills

In developing countries, several unregulated landfills exist adjacent to large cities, releasing harmful contaminants to the underlying aquifer. Normally, landfills are constructed to hold three types of waste, namely hazardous waste, municipal solid waste, and construction and demolition waste. Hazardous waste and municipal solid waste landfills are of greater importance as these pose greater hazard to groundwater, in comparison with landfills holding waste from construction and demolition. The polluting landfills need to be prioritized to undertake necessary control and remedial measures. This paper assesses existing site hazard rating systems and presents a new groundwater contamination hazard rating system for landfills, which can be used for site prioritization. The proposed system is based on source-pathway-receptor relationships and evaluates different sites relative to one another. The system parameters have been selected based on literature. The Delphi technique is used to derive the relative importance weights of the system parameters. The proposed system is compared with nine existing systems. The comparison shows that the site hazard scores produced by the existing systems for hazardous waste, municipal solid waste, and construction and demolition waste landfills are of the same order of magnitude and tend to overlap each other but the scores produced by the proposed system for the three types of landfills vary almost by an order of magnitude, which shows that the proposed system is more sensitive to the type of waste. The comparison further shows that the proposed system exhibits greater sensitivity also to varied site conditions. The application of different systems to six old municipal solid waste landfills shows that whereas the existing systems produce clustered scores, the proposed system produces significantly differing scores for all the six landfills, which improves decision making in site ranking. This demonstrates that the proposed system makes a better tool for prioritization of landfills for adopting control measures and remediation.     

Techno-economic analysis and environmental impact assessment of energy recovery from Municipal Solid Waste (MSW) in Brazil

Due to the lack of appropriate policies in the last decades, 60% of Brazilian cities still dump their waste in non-regulated landfills (the remaining ones dump their trash in regulated landfills), which represent a serious environmental and social problem. The key objective of this study is to compare, from a techno-economic and environmental point of view, different alternatives to the energy recovery from the Municipal Solid Waste (MSW) generated in Brazilian cities. The environmental analysis was carried out using current data collected in Betim, a 450,000 inhabitants city that currently produces 200 tonnes of MSW/day. Four scenarios were designed, whose environmental behaviour were studied applying the Life Cycle Assessment (LCA) methodology, in accordance with the ISO 14040 and ISO 14044 standards. The results show the landfill systems as the worst waste management option and that a significant environmental savings is achieved when a wasted energy recovery is done. The best option, which presented the best performance based on considered indicators, is the direct combustion of waste as fuel for electricity generation. The study also includes a techno-economical evaluation of the options, using a developed computer simulation tool. The economic indicators of an MSW energy recovery project were calculated. The selected methodology allows to calculate the energy content of the MSW and the CH₄ generated by the landfill, the costs and incomes associated with the energy recovery, the sales of electricity and carbon credits from the Clean Development Mechanism (CDM). The studies were based on urban centres of 100,000, 500,000 and 1,000,000 inhabitants, using the MSW characteristics of the metropolitan region of Belo Horizonte. Two alternatives to recovering waste energy were analyzed: a landfill that used landfill biogas to generate electricity through generator modules and a Waste-to-Energy (WtE) facility also with electricity generation. The results show that power generation projects using landfill biogas in Brazil strongly depend on the existence of a market for emissions reduction credits. The WtE plant projects, due to its high installation, Operation and Maintenance (O&M) costs, are highly dependent on MSW treatment fees. And they still rely on an increase of three times the city taxes to become attractive.     

Potential for enhanced phytoremediation of landfills using biosolids – a review

Despite the use of recyclable materials increasing worldwide, waste disposal to landfill remains the most common method of waste management because it is simple and relatively inexpensive. Although landfill disposal is an effective waste management system, if not managed correctly, a number of potential detrimental environmental impacts have been identified including soil and ground water contamination, leachate generation, and gas emissions. In particular, improper post-closure treatment of landfills or deterioration of the conventional clay landfill capping were shown to result in land degradation which required remediation to secure contaminants within the landfill site.Phytoremediation is an attractive technology for landfill remediation, as it can stabilize soil and simultaneously remediate landfill leachate. In addition, landfill phytoremediation systems can potentially be combined with landfill covers (Phytocapping) for hydrological control of infiltrated rainfall. However, for the successful application of any phytoremediation system, the effective establishment of appropriate, desired vegetation is critical. This is because the typically harsh and sterile nature of landfill capping soil limits the sustainable establishment of vegetation. Therefore, the physicochemical properties of landfill capping soils often need to be improved by incorporating soil amendments. Biosolids are a common soil amendment and will often meet these demanding conditions because they contain a variety of plant nutrients such as nitrogen, phosphate, potassium, as well as a large proportion of organic matter. Such amendment will also ameliorate the physical properties of the capping soils by increasing porosity, moisture content, and soil aggregation. Contaminants which potentially originate from biosolids will also be remediated by activities congruent with the establishment of plants and bacteria.     

Evaluation of leachate recirculation on nitrous oxide production in the Likang Landfill,China

Landfill leachate recirculation is efficient in reducing the leachate quantity handled by a leachate treatment plant. However, after land application of leachate, nitrification and denitrification of the ammoniacal N becomes possible and the greenhouse gas nitrous oxide (N2O) is produced. Lack of information on the effects of leachate recirculation on N2O production led to a field study being conducted in the Likang Landfill (Guangzhou, China) where leachate recirculation had been practiced for 8 yr. Monthly productions and fluxes of N2O from leachate and soil were studied from June to November 2000. Environmental and chemical factors regulating N2O production were also accessed. An impermeable top liner was not used at this site; municipal solid waste was simply covered by inert soil and compacted by bulldozers. A high N2O emission rate (113 mg m-2 h-1) was detected from a leachate pond purposely formed on topsoil within the landfill boundary after leachate irrigation. A high N2O level (1.09 micrograms L-1) was detected in a gas sample emitted from topsoil 1 m from the leachate pond. Nitrous oxide production from denitrification in leachate-contaminated soil was at least 20 times higher than that from nitrification based on laboratory incubation studies. The N2O levels emitted from leachate ponds were compared with figures reported for different ecosystems and showed that the results of the present study were 68.7 to 88.6 times higher. Leachate recirculation can be a cost-effective operation in reducing the volume of leachate to be treated in landfill. However, to reduce N2O flux, leachate should be applied to underground soil rather than being irrigated and allowed to flow on topsoil.     

垃圾填埋场渗滤液回流技术研究进展

垃圾填埋场渗滤液回流能有效降低渗滤液中污染物的浓度，提高填埋场稳定化程度，具有广泛的应用前景。本文综述了国内外学者对该技术的研究情况，包括技术特点及相关机理、渗滤液特性研究及回流效果的影响因素，指出了该技术现存的不足之处和尚待解决的理论和技术问题。     

Comparison of energy produced from waste by removing its different components: A case study of the waste landfill in Tehran

In developing and populated cities such as Tehran, a massive amount of municipal solid waste (MSW), both wet and dry, is transferred to landfills daily. Combustion is one of the most common methods of using mixed waste energy from the past to the present. The Dulong formula is widely used to calculate the energy released from MSW combustion. According to the constituent components of Tehran MSW, removing food waste leads to an increase in energy potential, which will be a suitable condition for energy production. In this work, the energy derived from the combustion of mixed and separated dry MSW generated in Tehran was calculated using the experimental Dulong formula and tables in Integrated Solid Waste Management (Tchobanoglous et al. 1993, McGraw‐Hill). The Dulong formula indicates that the use of Tehran mixed MSW (without separating materials for recycling) as a fuel source yields 8,966.40 KJ/kg while the use of Tchobanoglous et al. (1993) tables can generate 8,236 kJ/kg. By removing food waste and recyclable materials, the potential of energy production changes to 22,047 kJ/kg using the Dulong formula and 16,207 kJ/kg and the Tchobanoglous et al. (1993) tables. It indicates increase by 1.46 times and 46%, respectively. Regarding the 200‐ton capacity of the Tehran waste incinerator, the Dulong formula indicated generation of 4,409 MJ/day energy, and the Tchobanoglous et al. table presents 3,241 MJ/day. Therefore, considering that Tehran generates more than 4,000 tons of reject waste daily, it can easily be converted to energy rather than landfilled. This can alleviate the problem of buying land and construction of landfills and leachate generation.