The role played by environmental factors in the integration of a transfer station in a municipal solid waste management system

Transfer stations are an integral part of present-day municipal solid waste management systems. The main criteria used to decide on the location of a transfer station has traditionally been the minimization of transport costs, since it is cheaper to transport great amounts of waste over long distances in large loads than in small ones. In this study, we are going to consider the environmental factor in order to compare the feasibility of using a transfer station integrated within a waste management system. Applying the Life Cycle Assessment technique will enable us to obtain an objective parameter that quantifies the environmental impact of transportation and of operating a transfer station. Taking the current rates of solid wastes generation in the Plana region of Castellón (Spain) as our starting point, in this study we compare the environmental costs involved in the process of taking municipal wastes directly to the nearest waste treatment facility, with those involved in a waste management system integrating a transfer station. Comparing these two cases, an average reduction of 16.8% in the environmental impact can be obtained when a transfer station is incorporated in the waste management system.     

An inexact multi-objective dynamic model and its application in China for the management of municipal solid waste

With the development of science and technology, solid waste management has become a serious environmental problem for most communities all over the world. This paper presents a multi-objective optimization model for the management of municipal solid waste (MSW) via an uncertainty approach. In this model, the system cost of solid waste management and the environmental impact are considered as the main objectives, and some necessary constraints based on the characteristics of China are included; additionally, Pollution loss theory is applied to evaluate the environmental impact.This model is applied to the City of Fo Shan, China. Compared with the primary project of Fo Shan, which is provided by the government, the results of the optimization procedure show that the overall system cost could be reduced by $1–2.4/ton, i.e., $3.7 million/yr. The model presented in this paper was proven to be an effective response to the multi-objective solid waste management problem, and provides a new technique to optimize MSW management and operation. Why is the optimization result better? By analyzing the modelling with respect to function, constraints, and results, we conclude that the profit would be augmented due to the amount of the waste that would be treated by recycling technology, which would increase rapidly during the planning time; thus, the total system cost could be reduced accordingly.     

Optimal planning for the sustainable utilization of municipal solid waste

The increasing generation of municipal solid waste (MSW) is a major problem particularly for large urban areas with insufficient landfill capacities and inefficient waste management systems. Several options associated to the supply chain for implementing a MSW management system are available, however to determine the optimal solution several technical, economic, environmental and social aspects must be considered. Therefore, this paper proposes a mathematical programming model for the optimal planning of the supply chain associated to the MSW management system to maximize the economic benefit while accounting for technical and environmental issues. The optimization model simultaneously selects the processing technologies and their location, the distribution of wastes from cities as well as the distribution of products to markets. The problem was formulated as a multi-objective mixed-integer linear programing problem to maximize the profit of the supply chain and the amount of recycled wastes, where the results are showed through Pareto curves that tradeoff economic and environmental aspects. The proposed approach is applied to a case study for the west-central part of Mexico to consider the integration of MSW from several cities to yield useful products. The results show that an integrated utilization of MSW can provide economic, environmental and social benefits.     

Multi-objective optimization of solid waste flows: environmentally sustainable strategies for municipalities

An approach to sustainable municipal solid waste (MSW) management is presented, with the aim of supporting the decision on the optimal flows of solid waste sent to landfill, recycling and different types of treatment plants, whose sizes are also decision variables. This problem is modeled with a non-linear, multi-objective formulation. Specifically, four objectives to be minimized have been taken into account, which are related to economic costs, unrecycled waste, sanitary landfill disposal and environmental impact (incinerator emissions). An interactive reference point procedure has been developed to support decision making; these methods are considered appropriate for multi-objective decision problems in environmental applications. In addition, interactive methods are generally preferred by decision makers as they can be directly involved in the various steps of the decision process. Some results deriving from the application of the proposed procedure are presented. The application of the procedure is exemplified by considering the interaction with two different decision makers who are assumed to be in charge of planning the MSW system in the municipality of Genova (Italy).     

A multi-objective programming model for assessment the GHG emissions in MSW management

In this study a multi-objective mathematical programming model is developed for taking into account GHG emissions for Municipal Solid Waste (MSW) management. Mathematical programming models are often used for structure, design and operational optimization of various systems (energy, supply chain, processes, etc.). The last twenty years they are used all the more often in Municipal Solid Waste (MSW) management in order to provide optimal solutions with the cost objective being the usual driver of the optimization. In our work we consider the GHG emissions as an additional criterion, aiming at a multi-objective approach. The Pareto front (Cost vs. GHG emissions) of the system is generated using an appropriate multi-objective method. This information is essential to the decision maker because he can explore the trade-offs in the Pareto curve and select his most preferred among the Pareto optimal solutions. In the present work a detailed multi-objective, multi-period mathematical programming model is developed in order to describe the waste management problem. Apart from the bi-objective approach, the major innovations of the model are (1) the detailed modeling considering 34 materials and 42 technologies, (2) the detailed calculation of the energy content of the various streams based on the detailed material balances, and (3) the incorporation of the IPCC guidelines for the CH₄ generated in the landfills (first order decay model). The equations of the model are described in full detail. Finally, the whole approach is illustrated with a case study referring to the application of the model in a Greek region.     

Conceptual modeling to optimize the haul and transfer of municipal solid waste

Two conceptual mixed integer linear optimization models were developed to optimize the haul and transfer of municipal solid waste (MSW) prior to landfilling. One model is based on minimizing time (h/d), whilst the second model is based on minimizing total cost (euro/d). Both models aim to calculate the optimum pathway to haul MSW from source nodes (waste production nodes, such as urban centers or municipalities) to sink nodes (landfills) via intermediate nodes (waste transfer stations). The models are applicable provided that the locations of the source, intermediate and sink nodes are fixed. The basic input data are distances among nodes, average vehicle speeds, haul cost coefficients (in euro/ton km), equipment and facilities' operating and investment cost, labor cost and tipping fees. The time based optimization model is easier to develop, since it is based on readily available data (distances among nodes). It can be used in cases in which no transfer stations are included in the system. The cost optimization model is more reliable compared to the time model provided that accurate cost data are available. The cost optimization model can be a useful tool to optimally allocate waste transfer stations in a region and can aid a community to investigate the threshold distance to a landfill above which the construction of a transfer station becomes financially beneficial. A sensitivity analysis reveals that queue times at the landfill or at the waste transfer station are key input variables. In addition, the waste transfer station ownership and the initial cost data affect the optimum path. A case study at the Municipality of Athens is used to illustrate the presented models.     

A multi-echelon supply chain model for municipal solid waste management system

In this paper, a multi-echelon multi-period solid waste management system (MSWM) was developed by inoculating with multi-echelon supply chain. Waste managers, suppliers, industries and distributors could be engaged in joint strategic planning and operational execution. The principal of MSWM system is interactive planning of transportation and inventory for each organization in waste collection, delivery and disposal. An efficient inventory management plan for MSWM would lead to optimized productivity levels under available capacities (e.g., transportation and operational capacities). The applicability of the proposed system was illustrated by a case with three cities, one distribution and two waste disposal facilities. Solutions of the decision variable values under different significant levels indicate a consistent trend. With an increased significant level, the total generated waste would be decreased, and the total transported waste through distribution center to waste to energy and landfill would be decreased as well.     

Optimization of municipal solid waste management in Port Said - Egypt

Optimization of solid waste management systems using operational research methodologies has not yet been applied in any Egyptian governorate. In this paper, a proposed model for a municipal solid waste management system in Port Said, Egypt is presented. It includes the use of the concept of collection stations, which have not yet been used in Egypt. Mixed integer programming is used to model the proposed system and its solution is performed using MPL software V4.2. The results show that the best model would include 27 collection stations of 15-ton daily capacity and 2 collection stations of 10 ton daily capacity. Any transfer of waste between the collection station and the landfill should not occur. Moreover, the flow of the district waste should not be confined to the district collection stations. The cost of the objective function for this solution is 10,122 LE/day (equivalent to 1716 US dollars). After further calculations, the profit generated by the proposed model is 49,655.8 LE/day (equivalent to 8418.23 US dollars).     

A dynamic optimization model for solid waste recycling

Recycling is an important part of waste management (that includes different kinds of issues: environmental, technological, economic, legislative, social, etc.). Differently from many works in literature, this paper is focused on recycling management and on the dynamic optimization of materials collection. The developed dynamic decision model is characterized by state variables, corresponding to the quantity of waste in each bin per each day, and control variables determining the quantity of material that is collected in the area each day and the routes for collecting vehicles. The objective function minimizes the sum of costs minus benefits. The developed decision model is integrated in a GIS-based Decision Support System (DSS). A case study related to the Cogoleto municipality is presented to show the effectiveness of the proposed model. From optimal results, it has been found that the net benefits of the optimized collection are about 2.5 times greater than the estimated current policy.     

An environmentally sustainable decision model for urban solid waste management

The aim of this work is to present the structure and the application of a decision support system (DSS) designed to help decision makers of a municipality in the development of incineration, disposal, treatment and recycling integrated programs. Specifically, within a MSW management system, several treatment plants and facilities can generally be found: separators, plants for production of refuse derived fuel (RDF), incinerators with energy recovery, plants for treatment of organic material, and sanitary landfills. The main goal of the DSS is to plan the MSW management, defining the refuse flows that have to be sent to recycling or to different treatment or disposal plants, and suggesting the optimal number, the kinds, and the localization of the plants that have to be active. The DSS is based on a decision model that requires the solution of a constrained non-linear optimization problem, where some decision variables are binary and other ones are continuous. The objective function takes into account all possible economic costs, whereas constraints arise from technical, normative, and environmental issues. Specifically, pollution and impacts, induced by the overall solid waste management system, are considered through the formalization of constraints on incineration emissions and on negative effects produced by disposal or other particular treatments.     

Environmental impact assessment of solid waste management in Beijing City, China

The environmental impacts of municipal solid waste management in Beijing City were evaluated using a life-cycle-based model, EASEWASTE, to take into account waste generation, collection, transportation, treatment/disposal technologies, and savings obtained by energy and material recovery. The current system, mainly involving the use of landfills, has manifested significant adverse environmental impacts caused by methane emissions from landfills and many other emissions from transfer stations. A short-term future scenario, where some of the landfills (which soon will reach their capacity because of rising amount of waste in Beijing City) are substituted by incinerators with energy recovery, would not result in significant environmental improvement. This is primarily because of the low calorific value of mixed waste, and it is likely that the incinerators would require significant amounts of auxiliary fuels to support combustion of wet waste. As for the long-term future scenario, efficient source separation of food waste could result in significant environmental improvements, primarily because of increase in calorific value of remaining waste incinerated with energy recovery. Sensitivity analysis emphasized the importance of efficient source separation of food waste, as well as the electricity recovery in incinerators, in order to obtain an environmentally friendly waste management system in Beijing City.     

A model to minimize joint total costs for industrial waste producers and waste management companies.

The model LINKopt is a mixed-integer, linear programming model for mid- and long-term planning of waste management options on an inter-company level. There has been a large increase in the transportation of waste material in Germany, which has been attributed to the implementation of the European Directive 75/442/EEC on waste. Similar situations are expected to emerge in other European countries. The model LINKopt has been developed to determine a waste management system with minimal decision-relevant costs considering transportation, handling, storage and treatment of waste materials. The model can serve as a tool to evaluate various waste management strategies and to obtain the optimal combination of investment options. In addition to costs, ecological aspects are considered by determining the total mileage associated with the waste management system. The model has been applied to a German case study evaluating different investment options for a co-operation between Daimler-Chrysler AG at Rastatt, its suppliers, and the waste management company SITA P+R GmbH. The results show that the installation of waste management facilities at the premises of the waste producer would lead to significant reductions in costs and transportation.     

Minimax regret optimization analysis for a regional solid waste management system

Solid waste management (SWM) facilities are crucial for environmental management and public health in urban regions. Due to the waste management hierarchy, one of the greatest challenges that organizations face today is to figure out how to diversify the treatment options, increase the reliability of infrastructure systems, and leverage the redistribution of waste streams among incineration, compost, recycling, and other facilities to their competitive advantage region wide. Systems analysis plays an important role for regionalization assessment of integrated SWM systems, leading to provide decision makers with break-through insights and risk-informed strategies. This paper aims to apply a minimax regret optimization analysis for improving SWM strategies in the Lower Rio Grande Valley (LRGV), an economically fast growing region in the US. Based on different environmental, economic, legal, and social conditions, event-based simulation in the first stage links estimated waste streams in major cities in LRGV with possible solid waste management alternatives. The optimization analysis in the second stage emphasizes the trade-offs and associated regret evaluation with respect to predetermined scenarios. Such optimization analyses with multiple criteria have featured notable successes, either by public or private efforts, in diverting recyclables, green waste, yard waste, and biosolids from the municipal solid waste streams to upcoming waste-to-energy, composting, and recycling facilities. Model outputs may link prescribed regret scenarios in decision making with various scales of regionalization policies. The insights drawn from the system-oriented, forward-looking, and preventative study can eventually help decision-makers and stakeholders gain a scientific understanding of the consequences of short-term and long-term decisions relating to sustainable SWM in the fast-growing US-Mexico borderland.     

Experience with the use of LCA-modelling (EASEWASTE) in waste management.

Life-cycle assessment (LCA) models are becoming the principal decision support tools of waste management systems. This paper describes our experience with the use of EASEWASTE (Environmental Assessment of Solid Waste Systems and Technologies), a new computerized LCA-based model for integrated waste management. Our findings provide a quantitative understanding of waste management systems and may reveal consistent approaches to improve their environmental performances. EASEWASTE provides a versatile system modelling facility combined with a complete life-cycle impact assessment and in addition to the traditional impact categories addresses toxicity-related categories. New categories dealing with stored ecotoxicity and spoiled groundwater resources have been introduced. EASEWASTE has been applied in several studies, including full-scale assessments of waste management in Danish municipalities. These studies led to numerous modelling issues: the need of combining process-specific and input-specific emissions, the choice of a meaningful time horizon, the way of accounting for biological carbon emissions, the problem of stored ecotoxicity and aspects of crediting the waste management system with the savings inherent in avoided production of energy and materials. Interpretation of results showed that waste management systems can be designed in an environmentally sustainable manner where energy recovery processes lead to substantial avoidance of emissions and savings of resources.     

Application of the WAMED model to landfilling

A cost methodology is proposed for evaluating the ecological-economic efficiency of a municipal solid waste management scheme based on the recommendations of cost-benefit analysis and the full-cost accounting methodology for municipal solid waste management. The methodology employs the previously introduced waste managements’ efficient decision (WAMED) model and the company statistical business tool for environmental recovery (COSTBUSTER) indicator. A case study presents the practical application of the proposed cost-benefit analysis-based theory to the landfilling concept currently applied in Kalmar, Sweden. It is concluded that the presented provisions for evaluation of the ecological-economic efficiency of a municipal solid waste management scheme reflect a novel integrated approach to solving the problem of simultaneously decreasing the negative impacts of municipal solid waste on the environment and the health of the population while providing an information support tool for decision making in municipal solid waste management at regional and municipal levels to improve small-and medium-sized company competitiveness in particular.     

A hybrid procedure for MSW generation forecasting at multiple time scales in Xiamen City,China

Accurate forecasting of municipal solid waste (MSW) generation is crucial and fundamental for the planning, operation and optimization of any MSW management system. Comprehensive information on waste generation for month-scale, medium-term and long-term time scales is especially needed, considering the necessity of MSW management upgrade facing many developing countries. Several existing models are available but of little use in forecasting MSW generation at multiple time scales. The goal of this study is to propose a hybrid model that combines the seasonal autoregressive integrated moving average (SARIMA) model and grey system theory to forecast MSW generation at multiple time scales without needing to consider other variables such as demographics and socioeconomic factors. To demonstrate its applicability, a case study of Xiamen City, China was performed. Results show that the model is robust enough to fit and forecast seasonal and annual dynamics of MSW generation at month-scale, medium- and long-term time scales with the desired accuracy. In the month-scale, MSW generation in Xiamen City will peak at 132.2 thousand tonnes in July 2015 – 1.5 times the volume in July 2010. In the medium term, annual MSW generation will increase to 1518.1 thousand tonnes by 2015 at an average growth rate of 10%. In the long term, a large volume of MSW will be output annually and will increase to 2486.3 thousand tonnes by 2020 – 2.5 times the value for 2010. The hybrid model proposed in this paper can enable decision makers to develop integrated policies and measures for waste management over the long term.     

A multiobjective modeling approach to locate multi-compartment containers for urban-sorted waste

The location of multi-compartment sorted waste containers for recycling purposes in cities is an important problem in the context of urban waste management. The costs associated with those facilities and the impacts placed on populations are important concerns. This paper introduces a mixed-integer, multiobjective programming approach to identify the locations and capacities of such facilities. The approach incorporates an optimization model in a Geographical Information System (GIS)-based interactive decision support system that includes four objectives. The first objective minimizes the total investment cost; the second one minimizes the average distance from dwellings to the respective multi-compartment container; the last two objectives address the “pull” and “push” characteristics of the decision problem, one by minimizing the number of individuals too close to any container, and the other by minimizing the number of dwellings too far from the respective multi-compartment container. The model determines the number of facilities to be opened, the respective container capacities, their locations, their respective shares of the total waste of each type to be collected, and the dwellings assigned to each facility. The approach proposed was tested with a case study for the historical center of Coimbra city, Portugal, where a large urban renovation project, addressing about 800 buildings, is being undertaken. This paper demonstrates that the models and techniques incorporated in the interactive decision support system (IDSS) can be used to assist a decision maker (DM) in analyzing this complex problem in a realistically sized urban application. Ten solutions consisting of different combinations of underground containers for the disposal of four types of sorted waste in 12 candidate sites, were generated. These solutions and tradeoffs among the objectives are presented to the DM via tables, graphs, color-coded maps and other graphics. The DM can then use this information to “guide” the IDSS in identifying additional solutions of potential interest. Nevertheless, this research showed that a particular solution with a better objective balance can be identified. The actual sequence of additional solutions generated will depend upon the objectives and preferences of the DM in a specific application.     

A methodology for optimal MSW management,with an application in the waste transportation of Attica Region,Greece

The paper describes a software system capable of formulating alternative optimal Municipal Solid Wastes (MSWs) management plans, each of which meets a set of constraints that may reflect selected objections and/or wishes of local communities. The objective function to be minimized in each plan is the sum of the annualized capital investment and annual operating cost of all transportation, treatment and final disposal operations involved, taking into consideration the possible income from the sale of products and any other financial incentives or disincentives that may exist. For each plan formulated, the system generates several reports that define the plan, analyze its cost elements and yield an indicative profile of selected types of installations, as well as data files that facilitate the geographic representation of the optimal solution in maps through the use of GIS. A number of these reports compare the technical and economic data from all scenarios considered at the study area, municipality and installation level constituting in effect sensitivity analysis. The generation of alternative plans offers local authorities the opportunity of choice and the results of the sensitivity analysis allow them to choose wisely and with consensus.The paper presents also an application of this software system in the capital Region of Attica in Greece, for the purpose of developing an optimal waste transportation system in line with its approved waste management plan. The formulated plan was able to: (a) serve 113 Municipalities and Communities that generate nearly 2 million t/y of comingled MSW with distinctly different waste collection patterns, (b) take into consideration several existing waste transfer stations (WTS) and optimize their use within the overall plan, (c) select the most appropriate sites among the potentially suitable (new and in use) ones, (d) generate the optimal profile of each WTS proposed, and (e) perform sensitivity analysis so as to define the impact of selected sets of constraints (limitations in the availability of sites and in the capacity of their installations) on the design and cost of the ensuing optimal waste transfer system. The results show that optimal planning offers significant economic savings to municipalities, while reducing at the same time the present levels of traffic, fuel consumptions and air emissions in the congested Athens basin.     

化工过程废物最小化方法的研究进展

系统化的废物最小化方法对于环境友好且具有竞争力的化工过程的研发、综合、设计和改造具有非常重要的指导作用。简介了废物最小化的一般原则;综述了目前国内外各类系统的废物最小化方法,包括定性类方法如分层决策法、环境优化技术法、结构化法及3Es法等,定量类方法如各种数学优化法、夹点分析法、废物削减算法以及人工智能法及组合式方法;展望了该领域的研究发展趋势。     

Medical waste management in Trachea region of Turkey: suggested remedial action.

The main objective of this paper was to analyse the present status of medical waste management in the Trachea region of Turkey and subsequently to draw up a policy regarded with generation, collection, on-site handling, storage, processing, recycling, transportation and safe disposal of medical wastes. This paper also presents the results of study about awareness on how to handle expired drugs. Initially all health-care establishments in Tekirda?, Edirne and Kyrklareli provinces in Trachea region were identified and the amounts of hospital wastes generated by each of them were determined. Current medical waste-management practices, including storage, collection, transportation and disposal, in surveyed establishments were identified. Finally, according to results, remedial measurements for medical waste management in these establishments were suggested. Unfortunately, medical wastes are not given proper attention and these wastes are disposed of together with municipal and industrial solid wastes. The current disposal method is both a public health and environmental hazard. When landfill sites are visited, many scavengers can be seen sorting for recyclable materials, a practice which is dangerous for the scavengers. In addition, it was found that some staff in health-care establishments are unaware of the hazard of medical wastes. It is concluded that a new management system, which consists of segregation, material substitution, minimization, sanitary landfilling and alternative medical waste treatment methods should be carried out. For the best appropriate medical waste management system, health-care establishment employers, managers and especially the members of house- keeping divisions should be involved in medical waste management practice.