Environmental assessment of municipal solid waste composting: Comparing landfilling and incineration scenarios towards a sustainable approach.

Few studies have examined differing interpretations of life cycle impact assessment (LCIA) results between midpoints and endpoints for the same systems. This paper focuses on the LCIA of municipal solid waste (MSW) systems by taking both the midpoint and endpoint approaches and uses LIME (Life Cycle Impact Assessment Method based on Endpoint Modeling, version 2006). With respect to global and site-dependent factors, environmental impact categories were divided into global, regional, and local scales. Results are shown as net emissions consisting of system emissions and avoided emissions. This study is divided into five segments. The first segment develops the LCIA framework and four MSW scenarios based on the current MSW composition and systems of Seoul, considering adaptable results from the hierarchy MSW systems. In addition, two systems are considered: main MSW systems and optional systems. Several “what if” scenarios are discussed, including various compositions and classifications of MSW. In the second segment, life cycle inventory (LCI) analysis is applied to define various inputs and outputs to and from MSW systems, including air (23 categories), water (28 categories) and land (waste) emissions, resource consumption, land use, recovered material, compost, landfill gas, biogas, and heat energy. The third segment, taking the midpoint approach, investigates the nine environmental impacts of the system and avoided emissions. In the fourth segment, this study, taking the endpoint approach, evaluates the damages, dividing the four safeguard subjects affected by 11 environmental impact categories of the system and avoided emissions. In these third and fourth segments, LCIA is applied to analyze various end-of-life scenarios for same MSW materials. The final segment defines the differences from the results in accordance with the two previous life cycle assessment methodologies (the LCIA and interpretations with respect to midpoints and endpoints). With the respect to midpoints, Scenario 1 (S1) using 100% landfills (L) is the worst performer in terms of global (global warming and resource consumption), regional (acidification, human toxicity, and ecotoxicity), and local (waste: landfill volume) impacts. In terms of all impacts except global warming and waste, Scenario 2 (S2) using 64.2% L and 35.8% material recycling (MR) was found to be the most effective system. With respect to global-scale endpoints, S1 was the worst performer in terms of human health and social assets, whereas the other scenarios with MR were poor and bad performers in terms of biodiversity and primary production. With respect to regional- and local-scale endpoints, S1 was the worst performer in terms of human health, biodiversity, and primary production, whereas Scenario 4 (S4) using 4.2% L (only incombustibles), 35.8% MR, 28.5% biological treatment (BT), and 31.5% incineration (I) was the worst performer in terms of social assets. S4 was the best performer in terms of global-scale endpoints, whereas S2 and Scenario 3 (S3, using 35.7% L, 35.8% MR, and 28.5% BT) were the best on regional- and local-scale endpoints, respectively. With respect to the monetization analysis, which considered net emissions and integrated all endpoints, S3 was found to be “the most effective system,” indicating US $31.6 savings per ton-waste. The results of this study illustrate the differences in the LCIA outcomes and interpretations with respect to the midpoint and endpoint approaches. In addition, it would be possible to interpret the effect of each indicator on safeguard subjects by integrating separate midpoints. The LCIA results of each endpoint for the scenarios were generally consistent with those of each midpoint. However, the results changed dramatically when the main contributor was a new category not included in midpoint categories. The key advantage with respect to grouping impact categories in the midpoint and endpoint approaches can be described as “the simplification of midpoints and the segmentation of endpoints.” This research raises many questions that warrant further research. This method does not provide an uncertainty evaluation of input data at the inventory level; it addresses only the main contributor for each impact category to four endpoints. In addition, it would be beneficial to investigate the suitability of midpoints and endpoints for different stakeholders with a low or high level of environmental expertise by comparing previous studies.

The effects of municipal solid waste (MSW) materials on growth, yield, and mineral element concentrations in tomato (Lycopersicon esculentum Mill.) (1991 and 1992) and squash (Cucurbita maxima Duch. Ex Lam.) (1992 and 1993) were evaluated. Agrisoil compost (composted trash), Eweson compost (co-composted trash and sewage sludge), or Daorganite sludge (chemically and heat-treated sewage sludge) were incorporated into calcareous limestone soil of southern Florida. The control had no MSW material added to the soil. The effect of MSW on crop growth, yield, and mineral element concentrations varied considerably between years for tomato and squash. In 1991, tomato plants grown in soil amended with Eweson or Daorganite had a greater canopy volume than plants in the control treatment. Tomato plants grown in Daorganite had greater total fruit weight (1991) than plants in Agrisoil and more marketable fruit (1992) than control plants. In both years, tomato plants in Agrisoil had higher root Zn concentrations than plants in the other treatments. In 1992, tomato plants in Eweson had lower root Mn concentrations than plants in the other treatments, whereas Mg concentrations in the roots were higher in the Daorganite treatment than in Eweson. Tomato plants in Agrisoil had higher Pb concentrations in the roots than plants in all other treatments. In 1991, leaves of tomato plants in Agrisoil had lower Ca concentrations than leaves of plants in the control treatment. In 1992, leaf Zn concentrations were greater for tomato and squash in Agrisoil than in the control or Daorganite. In 1992, canopy volume and yield of squash were greater for plants in Daorganite than for plants in the control and other MSW treatments. Although canopy volume and total squash fruit weight did not differ among treatments in 1993, plant height was greater for squash plants in the MSW treatments than for those in the control. In 1993, leaf Mg concentrations were greater for squash grown in Daorganite than for plants in the control or Agrisoil. In 1993, fruit Cd concentration was higher for plants with Eweson than for plants in the control or Agrisoil. However, the fruit Cd concentration in squash grown in Eweson compost (1.0 mg/kg dry weight) was far below a hazardous level for human consumption. Our results indicate that amending calcareous soils with MSW materials can increase growth and yield of tomato and squash with negligible increases in heavy metal concentrations in fruit.

If municipal solid waste (MSW) is not properly managed, harmful environmental consequences are imminent. In many developed countries, MSW materials are hardly discarded but rather retained in the economic cycle through circular economy models. In many developing countries, MSW materials are discarded with little to no effort of repairing or recycling. Moving towards a circular economy substantially reduce waste volumes that are currently being disposed. The study provides an overview of how the current municipal solid waste management strategies being implemented by the Swakopmund Municipality could be shifted towards sustainability to derive environmental and socio-economic benefits from waste. Source reduction, separation at source and recycling, are some of the most effective strategies in the circular economy models that will help achieving the United Nations’ (UN) Sustainable Development Goals (SDGs). Swakopmund Municipality should invest in infrastructure, techniques and programmes that are within circular economy model as an emerging system for sustainability.

A considerable amount of settlement occurs due to the decomposition of municipal solid waste (MSW) in landfills over a period of years. Therefore, the effect of biological decomposition governs the long-term settlement characteristics of municipal solid waste landfills. In this study, we investigated the long-term settlement characteristics by applying a number of prediction methods to fresh MSW sites and predicting the settlement curves. Most proposed methods, excluding the power creep law, successfully predicted long-term settlement only if accelerated logarithmic compression due to decomposition of biodegradable MSW was included in the settlement prediction.

Municipal solid waste decomposition under oversaturated condition in comparison with leachate recirculation

Standard methods for assessing the environmental impact of waste management systems are needed to underpin the development and implementation of sustainable waste management practice. Life cycle assessment (LCA) is a tool for comprehensively ensuring such assessment and covers all impacts associated with waste management. LCA is often called “from cradle to grave” analysis. This paper integrates information on the greenhouse gas (GHG) implications of various management options for some of the most common materials in municipal solid waste (MSW). Different waste treatment options for MSW were studied in a system analysis. Different combinations of recycling (cardboard, plastics, glass, metals), biological treatment (composting), and incineration as well as land-filling were studied. The index of environmental burden in the global warming impact category was calculated. The calculations are based on LCA methodology. All emissions taking place in the whole life cycle system were taken into account. The analysis included “own emissions,” or emissions from the system at all stages of the life cycle, and “linked emissions,” or emissions from other sources linked with the system in an indirect way. Avoided emissions caused by recycling and energy recovery were included in the analysis. Displaced emissions of GHGs originate from the substitution of energy or materials derived from waste for alternative sources. The complex analysis of the environmental impact of municipal waste management systems before and after application of changes in MSW systems according to European Union regulations is presented in this paper. The evaluation is made for MSW systems in Poland.

Abiotic decomposition of municipal solid waste under elevated temperature landfill conditions

Advancing towards circular economy: Environmental benefits of an innovative biorefinery for municipal solid waste management

Viral community in landfill leachate: Occurrence, bacterial hosts, mediation antibiotic resistance gene dissemination, and function in municipal solid waste decomposition

If municipal solid waste (MSW) is not properly managed, harmful environmental consequences are imminent. MSW materials are rarely wasted in many affluent countries, but rather are kept in the economic cycle through circular economy models. While in many developing countries, MSW materials are discarded with little to no effort of repairing or recycling. Moving to a circular economy will drastically reduce the amount of waste currently disposed of. This study examines how the Swakopmund Municipality in Namibia’s present municipal solid waste management techniques could be adjusted toward sustainability to reap environmental and socioeconomic benefits from the trash. Source reduction, separation at source, and recycling are some of the most effective strategies in the circular economy models that will help achieve the United Nations (UN) Sustainable Development Goals (SDGs). Swakopmund Municipality should invest in infrastructure, techniques, and programs that are within the circular economy model as an emerging system for sustainability.

Separating recyclables from municipal solid waste (MSW) before collection reduces not only the quantity of MSW that needs to be treated but also the depletion of resources. However, the participation of residents is essential for a successful recycling program, and the level of participation usually depends on the degree of convenience associated with accessing recycling collection points. The residential accessing convenience (RAC) of a collection plan is determined by the proximity of its collection points to all residents and its temporal flexibility in response to resident requirements. The degree of proximity to all residents is determined by using a coverage radius that represents the maximum distance residents need to travel to access a recycling point. The temporal flexibility is assessed by the availability of proximal recycling points at times suitable to the lifestyles of all residents concerned. In Taiwan, the MSW collection is implemented at fixed locations and at fixed times. Residents must deposit their garbage directly into the collection vehicle. To facilitate the assignment of collection vehicles and to encourage residents to thoroughly separate their recyclables, in Taiwan MSW and recyclable materials are usually collected at the same time by different vehicles. A heuristic procedure including an integer programming (IP) model and ant colony optimization (ACO) is explored in this study to determine an efficient two-shift collection plan that takes into account RAC factors. The IP model has been developed to determine convenient collection points in each shift on the basis of proximity, and then the ACO algorithm is applied to determine the most effective routing plan of each shift. With the use of a case study involving a city in Taiwan, this study has demonstrated that collection plans generated using the above procedure are superior to current collection plans on the basis of proximity and total collection distance. IMPLICATIONS RAC is essential to the achievement of a successful tandem MSW and recyclable material collection plan. This study has proposed an optimization model and a metaheuristic tool to determine the routing plan. Through a real case study, a two-shift routing/scheduling plan is obtained by using the proposed procedure, which is to be superior to the existing collection plan. In short, local authorities that propose to determine a two-shift MSW and recyclable material collection plan should consider the proposed model as a basis of their operations.

Due to the rapid growth of population, urbanization and economic development, the generation of municipal solid waste (MSW) is increasing. Among all the waste materials in MSW, raw vegetable waste materials (RVW) are biodegradable in nature, and waste plastics (WPs) are non-biodegradable and impermeable in physical character. Previously, investigations are focused on the degradation of biodegradable materials without any physical presence of WP. But some of the present literatures reveal that WP need not to be separated from MSW as done in conventional technique before dumping in the landfill, rather mixing them uniformly with the other biodegradable waste materials and investigating the net effect on the biodegradation process of biodegradable materials may it be physical. The presence of waste plastics in the MSW beds changes the physical structure of the bed with more void pockets to hold a higher amount of leachate in the bed with higher retention time. Under these circumstances, the higher rate of degradation is inevitable since the degrading materials are constantly in contact with higher moisture leading to increasing in degradations. The present work, therefore, focuses on the studies of change of physical and structural characteristics of the MSW bed both in absence and presence of WP in different proportions within the specified optimum limit and at the same time improving the biogas generation. To measure the leachate hold-up and the compressibility of MSW bed, five small MSW beds were prepared with a certain amount of RVW and WP with an increasing amount such as 0, 5, 10, 15 and 20%, respectively. It was observed that the voidage and compressibility will be increasing with the increasing amount of WP. At the same time, percentage retention of leachate inside the waste bed was increased and may be attained the maximum with the range of 10–15%, which leads to the maximum production of biogas.

Biochemical decomposition of municipal solid waste (MSW) in landfills leads to the generation of leachate, gases and humus substances. In this context, a methodology to assess D ecomposition of MSW, designated as DecoMSW, has been developed; based on a series of tests conducted on samples of the fresh MSW and those retrieved from the active bioreactor landfill (BLF) cells of age from 13 to 48 months. Furthermore, spatial and temporal variation in the (i) physical (composition) and (ii) chemical (pH, volatile solids, total organic carbon, elemental analysis, ammonium and nitrate-nitrogen, biomethanation potential, lignocellulosic content) characteristics of the MSW samples exhumed from the landfill have been established. Finally, these characteristics were correlated vis-à-vis the respective values of the fresh MSW. From this exercise, it has been observed that except for nitrate-nitrogen, all other chemical parameters of MSW decrease exponentially with time until 20 months, and beyond that, they remain constant, which is an indication of stabilization of MSW. In short, it has been demonstrated that DecoMSW is instrumental in assessing the state of decomposition of MSW with respect to time in the BLF and facilitates initiation of the landfill mining activities.

A componential approach for evaluating the sources of trace metals in municipal solid waste

Mechanical-biological treatment of municipal solid waste: Case study of 100 TPD Goa plant, India