Evaluation of municipal solid waste composting kinetics

Most modern municipal solid waste (MSW) composting operations have emphasized the enhancement of decomposition of the organic fraction of the waste to comply with strict environmental regulations. This can be achieved once the composting process kinetics are well understood. This study examined process kinetics through experimentation with bench-scale reactors under controlled composting conditions to show the interdependence between biological, chemical and physical factors during composting of MSW. The effects of temperature, moisture content, waste particle size and carbon to nitrogen (C/N) ratio on process kinetics were evaluated. The results obtained revealed that these factors should be carefully controlled in order to achieve optimum process performance. It has been found that the organic matter degradation during composting follows a first-order kinetic model.     

Environmental and economic assessment of combined biostabilization and landfill for municipal solid waste

Biostabilization can remove considerable amounts of moisture and degradable organic materials from municipal solid waste (MSW), and can therefore be an effective form of pretreatment prior to landfill. The environmental and economic impacts of two combined processes, active stage biostabilization + sanitary landfill (AL), and active and curing stage biostabilization + sanitary landfill (ACL), were compared with sanitary landfill (SL) for MSW with high moisture content. The results indicated that land requirement, leachate generation, and CH(4) emission in the ACL process decreased by 68.6%, 89.1%, and 87.6%, respectively, and the total cost was reduced by 24.1%, compared with SL. This implies that a combined biostabilization and landfill process can be an environmentally friendly and economically feasible alternative to landfill of raw MSW with high moisture content. Sensitivity analysis revealed that treatment capacity and construction costs of biostabilization and the oxidation factor of CH(4) significantly influenced the costs and benefits of the AL and ACL process at an extremely low land price. When the land price was greater than 100 USD m(-2), it became the dominating factor in determining the cost of treatment and disposal, and the total costs of ACL were reduced to less than 40% of those of SL.     

A multi-objective location-allocation optimization for sustainable management of municipal solid waste

The location problem of treatment and service facilities in municipal solid waste (MSW) management system is of significant importance due to the socioeconomic and environmental concerns. The consideration of waste treatment costs, environmental impact, greenhouse gas (GHG) emissions, social fairness as well as other relevant aspects should be simultaneously taken into account when a MSW management system is planned. Development of sophisticated decision support tools for planning MSW management system in an economic-efficient and environmental friendly manner is therefore important. In this paper, a general multi-objective location-allocation model for optimally managing the interactions among those conflicting factors in MSW management system is proposed. The model is comprised of a three-stage conceptual framework and a mixed integer mathematical programming. The inclusion of environmental impact and GHG emission objectives push the output of the model tightening toward more environmentally friendly and sustainable solutions in MSW management. The application of this model is demonstrated through an illustrative example, and the computational efficiency of the programming is also tested through a set of incremental parameters. Latter in this paper, a comparison with previous case studies of MSW system design is presented in order to show the applicability and adaptability of the generic model in practical decision-making process, and the perspectives of future study are also discussed.     

Evidential role of municipal solid waste and liquid effluent on environment and public health

Cities in Bangladesh produce large amounts of solid waste (SW) through various human activities which severely pollutes our native environment. As a result, SW pollutes the three basic environmental elements (air, water, and soil) by increasing pathogenic microbial load, which might be hazardous to public health directly or indirectly. In this study, we conducted 30 samples (i.e., soil, water, and air) collected from areas where municipal solid wastes are dumped (Tangail Sadar Upazila, Bangladesh). All the samples were analyzed to assess bacteriological quality for presumptive viable and coliform count using different agar media. We performed serial dilution 10⁻³–10⁻¹⁰ times for soil and water samples, and the diluted samples were spread on Mac-Conkey agar and nutrient agar plates. For the air sample, the sterile media containing petri-dish was placed adjacent to the dumpsite of the municipal waste and kept for an hour. Then all the samples were incubated at 37°C overnight for total viable count (TVC) and total coliform count (TCC). Biochemical tests and PCR were performed for the identification of these microorganisms. The antibiogram study was performed to reveal their (identified bacteria) susceptibility against clinically used antibiotics according to the standard disk diffusion technique. The highest bacterial loads were found in the air: TVC 3.273 × 10³ and TCC 1.059 × 10³ CFU/plate; tube-well water: TVC 8.609 × 10³, and TCC 8.317 × 10³ CFU/mL; in surface water: TVC 6.24 × 10¹³ CFU/mL and TCC 2.2 × 10¹² CFU/mL; in soil: TVC 2.88 × 10¹¹ and TCC 1.02 × 10¹¹ CFU/g, respectively. Microbes from SW can be transmitted through air, dust particles, or flies, and here we found an average of 1120 microbes spread over 63.61 cm² area per hour. Eight bacterial isolates (Pseudomonas spp., Klebsiella spp., E. coli, Proteus spp., V. cholera, Salmonella spp., Shigella spp., and Vibrio spp.) were identified by the biochemical test. Among them, E. coli and Shigella spp. were further ensured by PCR targeting bfpA and ipaH genes. Antibiotic susceptibility test results showed that E. coli isolates were highly resistant to erythromycin (80%); Shigella spp. were resistant to nalidixic acid (90%), whereas Salmonella spp. was found resistant to kanamycin (90%). Vibrio spp. were also resistant to azithromycin (80%) and erythromycin (80%), which should be a great concern for us. A semi-structured survey revealed that 63% of respondents suffered from different clinical conditions (intestinal diseases) due to SW pollution. So, steps should be taken to improve the proper management and disposal of solid waste and liquid effluent to save our environment and public health.     

可用作原料的固体废物进口可行性评价指标体系探索研究

合理利用境外的可用作原料的固体废物,可以弥补我国国内资源的相对不足,但固体废物固有的废物属性仍不可避免地会带来一定的环境负面影响。建立可用作原料的固体废物进口可行性评价体系,对于在合理利用境外废物资源的同时,保护和改善环境具有重要意义。本文论述了我国建立可用作原料的固体废物进口可行性评价体系的理论和原则,并根据影响可用作原料的固体废物进口可行性评价的因素分析,构建了可用作原料的固体废物进口可行性评价指标体系框架。     

Alternative treatments for the municipal solid waste and domestic sewage in Campinas,Brazil

The treatments of municipal solid waste (MSW) and the domestic sewage (DS) are critical issues of the current political and environment discussions. These concerns are due to the lack of dumping areas, the continuous increase of the population, and public health issues. The adequate treatment and management of MSW and DS can produce many benefits such as financial funds, heat and energy production, reduction of emissions and recuperation of water for reuse. Currently in Campinas MSW and DS are deposited in landfills or discharged into rivers and other sites. In the present study two scenarios are evaluated for the treatment of MSW and DS in Campinas: recycling with biological treatment and recycling with thermal treatment. The most suitable treatments for Campinas, based on the data from the present analysis and taking into consideration the local conditions, maximization of energy potential and environmental benefits, are incineration for the MSW and biological treatment for DS, both with energy recuperation. The main gains of this option are substantial environmental benefits, generated energy which can reach 18% of the total electrical energy consumed in Campinas while about 53% recuperation of the total amount of water treated for Campinas in 2010.     

Evaluation of water treatment sludge for ameliorating acid mine waste

This study investigated the liming effect of water treatment sludge on acid mine spoils. The study was conducted with sludge from a water purification plant along the Vaal River catchments in South Africa. The optimum application rate for liming acid spoils and the speed and depth with which the sludge reacted with the mine waste were investigated. Chemical analysis indicated that the sludge is suitable as a liming agent because of its alkaline pH (8.08), high bicarbonate concentration (183.03 mg L(-1)), and low salinity (electrical conductivity = 76 mS m(-1)). The high cation exchange capacity of 15.47 cmol(c) kg(-1) and elevated nitrate concentration (73.16 mg L(-1)) also increase its value as an ameliorative material. The soluble concentrations for manganese, aluminum, lead, and selenium were high at a pH of 5 although only selenium (0.83 mg L(-1)) warranted some concern. According to experimental results, the application of 10 Mg ha(-1) of sludge to acid gold tailings increased the leach water pH from 4.5 to more than 7.5 and also increased the medium pH from 2.4 to 7.5. The addition of sludge further reduced the solubility of iron, manganese, copper, and zinc in the ameliorated gold tailings, but increased the electrical conductivity. The liming tempo was highest in the coal discard profile that had a coarse particle size distribution and took the longest to move through the gold tailings that had a fine particle size distribution. Results from this study indicate that the water treatment sludge investigated is suitable as a liming agent for rehabilitation of acid mine waste.     

Economical assessment of the design,construction and operation of open-bed biofilters for waste gas treatment

A protocol was developed with the purpose of assessing the main costs implied in the set-up, operation and maintenance of a waste gas-treating conventional biofilter. The main operating parameters considered in the protocol were the empty bed residence time and the gas flow rate. A wide variety of investment and operating costs were considered. In order to check its reliability, the protocol was applied to a number of scenarios, with biofilter volumes ranging from 8.3 to 4000 m³. Results show that total annualized costs were between 20?000 and 220?000 €/year and directly dependent, among other factors, on the size of the system. Total investment and operating costs for average-size compost biofilters were around 60?000 € and 20?000 €/year, respectively, which are concordant with actual costs. Also, a sensitivity analysis was performed in order to assess the relative influence of a series of selected costs. Results prove that operating costs are those that influence the total annual costs to a higher extent. Also, packing material replacement costs contribute significantly to the total yearly costs in biofilters with a volume higher than 800 m³. Among operating costs, the electricity consumption is the main influencing factor in biofilters with a gas flow rate above 50?000 m³/h, while labor costs are critical at lower gas flow rates. In addition, the use of a variety of packing materials commonly employed in biofiltration was assessed. According to the results obtained, special attention should be paid to the packing material selected, as it is the main parameter influencing the medium replacement costs, and one of the main factors affecting investment costs.     

兰炭生产过程中固体废物的产生与利用现状分析

在对国内兰炭生产工艺流程应用及现状介绍的基础上,概括总结了旧式低温干馏阶段和现阶段兰炭生产过程中固体废物的产生节点、种类、性质和主要处置方式。结果表明,旧式低温干馏阶段,兰炭生产过程中产生的固体废物主要包括煤筛分破碎工序产生的末煤和煤矸石、筛焦工序产生的焦粉、焦油冷却收集系统产生的焦油渣等;现阶段,兰炭生产过程中产生的固体废物主要包括煤筛分破碎工序产生的末煤和煤矸石以及破碎过程中经除尘器收集的煤尘、筛焦工序产生的焦粉、废水处理污泥、焦油冷却收集系统产生的焦油渣、脱硫工序产生的脱硫残液等。其中末煤、煤矸石、煤尘、焦粉作为一般工业固废全部综合利用,废水污泥、焦油渣、脱硫残液主要掺入原料煤中自行消化处置。     

Multiple regression models for the lower heating value of municipal solid waste in Taiwan

A multiple regression analysis was used to develop two predictive models of lower heating value (LHV) for municipal solid waste (MSW), using 180 samples gathered from cities and counties in Taiwan during 2001-2002. These models are referred to as the original proposed model (OPM) and the simplified model (SM). The coefficients of multiple determinations for the OPM and SM were 0.983 and 0.975, respectively. To verify the feasibility of the models, a demonstration program based on sampling of MSW in Kaohsiung City was conducted. As a result, the OPM showed superior precision in terms of relative percentage deviation (RPD) and mean absolute percentage error (MAPE), when compared to the conventional models based on the proximate analysis, physical composition and ultimate analysis. The SM was derived by neglecting the three minor physical components used in the OPM. The resulting SM was less precise when compared to the OPM, but it was still acceptable, with a precision level better than the conventional models. It was concluded that the predictability of empirical models could be improved significantly through selection of the appropriate physical components and multiple regression analysis.     

Analysis of volatile and semivolatile hydrocarbons recovered from steam-classified municipal solid waste

Hazardous household wastes comprise a significant proportion of municipal solid waste (MSW), and therefore serve as the source of many toxic or carcinogenic organic chemicals that are released in the environment through landfill gases or leachates. In the present study, we demonstrate the utility of the steam classification process in removing hazardous semivolatile organic compounds (SVOCs) and volatile organic compounds (VOCs) from MSW. Steam classification is a patented technology that involves the treatment of MSW with steam under pressure to yield a cellulosic biomass product that can be used as a fuel or in building materials. The SVOCs and VOCs from the waste off-gases are collected in the steam condensate and in an effluent charcoal filter. The results of this study show that at least two SVOCs and at least 17 VOCs can be removed from the waste. The most commonly identified compounds were diethylphthalate, styrene, 1,4-dichlorobenzene, and toluene in the condensates, and styrene, 1,1,1-trichloroethane, and toluene in the charcoal filters. On a weight basis, aromatic hydrocarbons were primarily recovered in the condensates, while the chloroaliphatic hydrocarbons were recovered almost exclusively from the charcoal filters. 1,3-Dichlorobenzene, 1,4-dichlorobenzene, and chloroform together comprised nearly 50% of the 4470 micrograms kg(-1) average mass of SVOCs and VOCs recovered from about 454 kg of MSW in these experiments. Toxicity characteristic leaching procedure (TCLP) analyses showed that steam classification recovered at least 75 to 91% of tested analytes. Overall, these results suggest that steam classification represents an effective technology for a significant reduction or the removal of hazardous organics from the waste stream, and, consequently, in reducing the extent of environmental contamination associated with landfill leachates and gases.     

Overview of household solid waste recycling policy status and challenges in Malaysia

With the annual increase in waste generation and heavy reliance on landfilling as disposal, method in Malaysia, it is just a matter of time before significant problems of space limitations, health, and environmental issues hit the nation severely. This paper attempts to develop an overview on solid, waste recycling in Malaysia at the most basic level of a community or nation which is the household, unit. Households are the main primary source of municipal solid waste in Malaysia, consisting of, recyclable materials at most 70% to 80% of the total waste composition as found placed in the, landfills. Overview on the existing household solid waste recycling policy and program status in, Malaysia is relevant in enhancing solid waste management measure from recycling perspective. Despite the high potential and opportunities for solid waste recycling, wastes are still simply being, dumped in an open area of ground without any attempt for recovery and recycling. Comparing to, recycling rates of neighboring countries, Malaysia is falling back at merely 5% which proves how, uncommon recycling practice is. The government is committed to significantly improve the national's, solid waste management services especially in waste minimization. Fortunately the emphasis on, recycling as a sustainable waste management strategy has taken a shift in paradigm as wastes, separation and recycling are part of the major changes in the current policy implementation. With, issues and challenges in recycling practice that were highlighted in this context especially from the, aspects of information availability and other loopholes within solid waste management policies and, related recycling program within the community, the question on whether the goals in 2020 can be, met remains unsure of but there is a possibility for a successful implementation of sustainable solid, waste management particularly in recycling.     

城市固体废弃物管理系统温室气体排放核算研究综述

城市固体废弃物管理系统是产生温室气体的一个不可忽视的排放源。随着社会经济的快速发展和城市化水平的提高,城市固体废弃物排放量逐年增多,如何准确地核算城市固体废弃物管理系统温室气体排放已成为国内外关注的热点问题之一。本文概述了城市固体废弃物管理系统的演进与优化研究进展,重点对城市固体废弃物管理系统温室气体排放核算规范和标准及其影响因素的研究进行了综述,指出了研究中存在的问题。并进一步建议今后在城市不同类别的固体废弃物管理系统演进过程及其影响、温室气体排放的核算方法、温室气体排放的校正系数、城市固体废弃物管理系统的优化模式及温室气体减排机制等方面加强研究。     

Assessing instruments for mixed household solid waste collection services in the Flemish region of Belgium

Instruments to reduce waste can be divided into three groups: first, pecuniary incentives; second, service level; finally, measurements stimulating prevention and waste reduction. Also specific characteristics of the community determine the amount of waste generated. We evaluate whether findings in literature on effectiveness of policy measures are valid for Belgium, specifically for the Flemish region. The policy mix instituted by the Flemish authorities in the ‘implementation plan household waste 2003–2007’ and implemented by local authorities, is assessed. Multiple regression analysis identifies those measurements having the greatest impact on household solid waste.We found an income elasticity of 0.326. Also the provided service level has a significant impact. Pecuniary incentives are effective instruments in reducing waste, with a price elasticity of −0.139. Furthermore, a higher percentage of direct costs, directly attributable to waste services, borne by households, reduces waste. A consequent implementation of the ‘polluter pays’ principle proves to be effective.     

Utilization of municipal solid waste (MSW) ash in cement and mortar

Solid waste management is gaining significant importance with the ever-increasing quantities of waste materials generated these days. With increased environmental awareness and its potential hazardous effects, recycling/utilization of these materials have become an attractive alternative to disposal. Some of these waste and hazardous materials could possible be used in cement-based materials. One of such waste is municipal solid waste. Ash is obtained after incineration of MSW.This paper presents comprehensive details of the physical, chemical, and mineralogical composition, elemental analysis of ash obtained from MSW. It also covers the effect of MSW ash on the hydration characteristics, setting times, compressive strength, sulfate resistance and mass loss of cement and mortar. It also deals with the leachate analysis of MSW ash.     

工业园区固体废物生命周期管理边界模型的构建

工业园区内企业众多,副产品和固体废物排放量大,生产过程也复杂,采用生命周期对固体废物进行管理显得也复杂很多。该文从构建工业园区固体废物生命周期管理边界模型出发,并以电子信息产业园区为例,试着将固体废物与不同的企业或生产过程紧密耦合,构建可行的较稳定的生命周期管理边界模型。     

基于IHS和PCA的CBERS与TM数据融合研究

以安徽省淮北市主城区为主要研究区域,采用2000年9月14日TM图像和2007年4月8日中巴资源卫星(CBERS-02)CCD数据作为数据源,主城区TM图像大小为239×338,CBERS图像大小为367×519.对两期遥感图像进行图像配准和去噪处理,运用IHS变换法和PCA变换法对TM图像和CBERS全色波段图像进行融合,并对融合结果进行了评价.     

洗毛碳化废水循环处理试验介绍

洗毛碳化废水处理是一项难度较大的科研课题,目前国内外尚无突破性进展。本文介绍从改革洗毛碳化工艺入手,采用多系统综合处理废水的试验结果。实验证明,经除泥渣和提取油脂后的废水,可循环使用至三天,节约了软水、蒸汽、洗剂、助剂,减少了排放量,降低了废水中有机物含量,费用支出略有盈余。最终将废水纳入二级处理系统,力争使废水达到国家排放标准。