Municipal Solid Waste Treatment System Research Articles

Environmental impact analysis of nitrogen cross-media metabolism: A case study of municipal solid waste treatment system in China

Municipal Solid Waste Treatment System (MSWTS) contributes a lot to urban metabolism optimization and pollution control of nitrogen. An analysis framework for cross-media metabolism of nitrogen was developed for MSWTS to study the systematic effects of nitrogen metabolism in MSWTS on ecosystem quality. Then cross-media distribution of pollutants was calculated in landfill, composting, incineration and anaerobic digestion, respectively. Sixty three percent to 82% of the original inputs ended up in the natural environment using the former three technologies (landfill, composting and incineration), which was attributed to cross-media migration. Anaerobic digestion should be highlighted due to its overall desirable removal efficiency. Critical processes related to nitrogen cross-media migration were identified to analyze the overall environmental impacts sensitivities. Positive effects emerged in liquid-solid interface migration of nitrogen through sewage collection and treatment technology processes, while the incineration flue gas treatment witnessed negative effects in gas-liquid interface migration. Overall, the environmental impact sensitivity levels of nitrogen cross-media migration under critical processes were as follows: incineration>landfill>composting>anaerobic digestion. Therefore, the environment is most sensitively affected by incineration and its processes. The present study is of great significance to optimize environmental management by shifting the management mode from single environmental medium quality control to systematic ecosystem quality improvement.

Managing competitive municipal solid waste treatment systems: An agent-based approach

Private sector participation in municipal solid waste (MSW) management is increasingly being applied in many countries recently. However, it remains a largely unexplored issue whether different self-interested treatment operators can co-exist in an economically feasible and sustainable manner. To help the policy-maker s understand and manage competitive MSW treatment systems, this paper proposes an agent-based waste treatment model (AWTM) that consists of four types of agents, namely the refuse collector, specialized treatment unit (STU), the general treatment unit (GTU), and the regulator. An estimation-and-optimization approach is developed for profit-maximizing agents to set optimal gate fee and vie for specific waste in low-information competition. Based on the Singapore case, the experimental results imply that if the regulator deliberately promotes the STUs by intervening in waste allocation, the GTU could give up competing for the waste and greatly increase its gate fees as retaliation. Besides, driven by the increasing gate fee of the GTU, the STUs conservatively raise their gate fee; while the GTU will be the major beneficiary in the AWTM. Finally, to identify the optimal mixed policy under predefined constraints, the AWTM is integrated into a simulation-based optimization problem, which is solved by a genetic algorithm.

How sustainable is organic packaging? A design method for recyclability assessment via a social perspective: A case study of Porto Alegre city (Brazil)

Current Brazilian municipal solid waste treatment system depends on public policy in maintaining Sorting Units, sites where low-income workers survive by selling sorted urban dry residues. Municipal waste departments often transport unsold post-sorted residues directly to landfills despite the possibility of recovery and recycling, thus lowering the income of the workers and consequently increasing the environmental impact. This study focused on industrialized organic food, which is cultivated in small, family-managed farms and is mostly sold on supermarket chains through regular packaging. Packaging recyclability is related to the feasibility of selling the sorted residues, including market value and buyers' interest, and may reveal important design guidelines for better packaging solutions. However, few studies have explored it as a method to assist in the design process. This study approaches organics' polymeric packaging recyclability through the social viewpoint of Sorting Units' workers of Porto Alegre City, Brazil. Porto Alegre's urban waste management system is described and followed by an overview of the Sorting Units' scenario. We analyzed more than 50 industrialized organic food packaging via Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. Common packaging features were listed and weighed, resulting in the generation of 15 subindexes. We developed a novel and simplified method for estimating the recyclability of organics polymeric packaging according to the current Sorting Units' criteria. Results showed that specific packaging features can significantly reduce or fully prevent the sell and consequent recycle of the dry waste. However, most of those characteristics could be replaced by simpler alternatives, thus increasing the selling possibilities in the Sorting Units. Finally, the simplified, binary equation of the design method can be applied by packaging designers and manufacturers to easily estimate the recyclability rate of a polymer packaging at a projection level.

一般廃棄物処理システム指針を活用した住民への情報提供の効果と課題

「市町村における循環型社会づくりに向けた一般廃棄物処理システムの指針 (環境省) ｣ のもつコミュニケーション・ツールとしての側面に着目し，情報提供が住民評価に与える影響を検討した。対象4市のごみ発生・処理状況を説明する図 (状況図) を指針に基づいて作成し，状況図を提示する回答群と提示しない回答群の2群に分けて，アンケート調査を行った。状況図による情報提供は，廃棄物施策に対する評価を厳しくする，または評価の判断材料にならない場合があることが示唆された。情報提供の際はデータの客観性を担保しつつ，解釈や関連情報を適切に付記する重要性を指摘した。また，住民は廃棄物行政に対する認識や信頼，支持の度合いが高ければ，ネガティブな情報に対しても過度に反応しないことが推察された。指針に基づく情報提供を，行政と住民の共通のコミュニケーション・ツールとして活用しつつ，信頼関係を築くことの重要性を指摘した。

Energy implications of mechanical and mechanical–biological treatment compared to direct waste-to-energy

Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical–biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation).The systems achieved net primary energy savings in a range between 34 and 140MJprimary/100MJinput waste, in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3–9.5%, 1–18% and 1–8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat recovery, the biodrying MBS-based system achieved the highest savings, on the condition of SRF co-combustion. As a sensitivity scenario, alternative utilisation of SRF in cement kilns was modelled. It supported similar or higher net savings for all pre-treatment systems compared to mass combustion WtE, except when WtE CHP was possible in the first two background energy scenarios. Recovery of plastics for recycling before energy recovery increased net energy savings in most scenario variations, over those of full stream combustion. Sensitivity to assumptions regarding virgin plastic substitution was tested and was found to mostly favour plastic recovery.

A Genetic-Algorithms-Based Approach for Programming Linear and Quadratic Optimization Problems with Uncertainty

This paper proposes a genetic-algorithms-based approach as an all-purpose problem-solving method for operation programming problems under uncertainty. The proposed method was applied for management of a municipal solid waste treatment system. Compared to the traditional interactive binary analysis, this approach has fewer limitations and is able to reduce the complexity in solving the inexact linear programming problems and inexact quadratic programming problems. The implementation of this approach was performed using the Genetic Algorithm Solver of MATLAB (trademark of MathWorks). The paper explains the genetic-algorithms-based method and presents details on the computation procedures for each type of inexact operation programming problems. A comparison of the results generated by the proposed method based on genetic algorithms with those produced by the traditional interactive binary analysis method is also presented.

一般廃棄物処理システムの設計における評価と意思決定の支援を志向したLCA手法の適用

Background, Aim and Scope. Municipal Solid Waste (MSW) management system has an important role to reduce final disposal of MSW. Recently prevention of global warming in MSW transportation and treatment processes is also coming into important. Decision makers in local region should design the MSW management system that solves above issues, and is desirable for the region in cost constraint. But there are few studies taking into account regional MSW discharge and waste treatment properties and their perspective. In this study, we proposed a methodology to design environmentally and economically desirable MSW management systems in local region by applying Life Cycle Assessment (LCA) and cost analysis.Materials and Methods. The central region of Iwate Prefecture was chosen as a case study. Firstly, we surveyed material and energy inputs/outputs in MSW transportation and treatment processes in the case study area. Then, Life Cycle Inventory (LCI) data of each process was calculated. Secondarily, scenarios involving several MSW management systems considering patterns of MSW treatment technologies and/or MSW segregation were designed. Results and Discussion. As a scenario analysis, Greenhouse Gas (GHG) emissions, SOx/NOx emissions, final disposal and the cost was calculated when each scenario would be for the period from FY2005 to FY2030. From the results, we found that the MSW treatment system in which municipalities form communal MSW treatment mostly has an advantage than the municipality-based MSW treatment system in which municipalities treat MSW by themselves. We also found the trade-off relationship in the results; a system giving priority to gasification and melting facilities decreases the amount of final disposal and cost and increases GHG emissions, while another system giving priority to stoker type grate facility decreases GHG emissions and cost and increases the amount of final disposal. However this trade-off relationship is solved by enhancing waste segregation and/or bio-methanation of kitchen garbage. Additionally, we calculated the indicator value of environmental impact by the Distance-to-target method, and we evaluated a relationship between the indicator value and the cost. As the result, scenario involving the region-based MSW treatment system with bio-methanation is selected as a desirable MSW management system if reduction of final disposal is prioritize as the MSW treatment policy. Conclusions. In the actual fields, it is required not only quantatative evaluation environmental impact and cost but also qualitative investigation such as site selection of waste treatment facilities considering NIMBY phenomenon. Nonetheless, the methodology proposed in this paper is effective for local municipalities’ decision support.

Model for evaluating the ecological health of municipal solid waste treatment system

Ecological municipal solid waste (MSW) treatment systems are complex systems engineering concerning with multiple objectives and hierarchical levels. By combining an extension method with fuzzy logic theory, this paper investigated key technologies required by the comprehensive evaluation of ecological health. The method includes the construction of an evaluation system, quantification of evaluation indices, development of a matter-element model, development of an extension evaluation method, and assignment of a blended weight that combines subjectively and objectively estimated weights. This approach was used to develop a comprehensive model for evaluating the ecological health of an ecological treatment system for MSW. The model was then applied to a case study, and the results demonstrated that the model is a reasonable and effective.

Summary of research on waste minimization studies by Japan waste research foundation (JWRF)

Japan is trying to provide a qualitatively better environment and the treatment of incinerator gas emissions is an indispensable part of pollution prevention programs. Therefore, a large part of incinerator wastes will be disposed of in landfills for municipal solid waste, and volume reduction and stabilization are major items on the technology agenda. For these reasons, the purpose of this research is waste minimization, namely reducing the volume of wastes that must be disposed of in landfills. This is being done by studying ways to use heat treatment to reduce the volume of incinerator ash, to develop technology for the effective use of treated material and to render fly ash and fused salts harmless. In addition, the author seeks to establish more advanced municipal solid waste treatment systems that reduce (slim) waste by using space efficiently and recovering metals in incinerator residue and fly ash for recycling.