The effect of separate collection of municipal solid waste on the lower calorific value of the residual waste

Greenhouse gas emission mitigation potential from municipal solid waste treatment: A combined SD-LMDI model

Fast urbanization and economic prosperity generate huge amount of municipal solid waste (MSW). It is therefore critical to identify the determinants of greenhouse gas (GHG) emissions from MSW treatment and prepare potential GHG mitigation measures. A combined System Dynamics - Logarithmic Mean Divisia Index model is developed to identify the driving forces of GHG emission generated from MSW treatment and explore the mitigation potentials. Shanghai, a typical megacity in China is selected as a case study. Results showed that economic development, population scale and emission intensity were driving forces to induce GHG emissions from MSW treatment, while generation intensity and treatment structure were the factors to mitigate GHG emissions from MSW during 2000-2017. Scenario analysis further revealed that landfill gas utilization and MSW separation improvement were the most effective measures in reducing GHG emissions from MSW treatment, leading to about 88.07% and 85.48% of reduction compared with the business-as-usual scenario in 2050. Scenarios of improving incineration rate, reducing per capita MSW generation and restricting population growth will reduce GHG emissions by 72.29%, 30.06% and 0.30%, respectively. Utilizing landfill gas, improving MSW separation and promoting green behaviors are suggested to mitigate GHG emissions from MSW treatment.

Life Cycle Assessment of Mixed Municipal Solid Waste: Multi-input versus multi-output perspective

This paper analyses four strategies for managing the Mixed Municipal Solid Waste (MMSW) in terms of their environmental impacts and potential advantages by means of Life Cycle Assessment (LCA) methodology. To this aim, both a multi-input and a multi-output approach are applied to evaluate the effect of these perspectives on selected impact categories. The analyzed management options include direct landfilling with energy recovery (S-1), Mechanical-Biological Treatment (MBT) followed by Waste-to-Energy (WtE) conversion (S-2), a combination of an innovative MBT/MARSS (Material Advanced Recovery Sustainable Systems) process and landfill disposal (S-3), and finally a combination of the MBT/MARSS process with WtE conversion (S-4). The MARSS technology, developed within an European LIFE PLUS framework and currently implemented at pilot plant scale, is an innovative MBT plant having the main goal to yield a Renewable Refined Biomass Fuel (RRBF) to be used for combined heat and power production (CHP) under the regulations enforced for biomass-based plants instead of Waste-to-Energy systems, for increased environmental performance. The four scenarios are characterized by different resource investment for plant and infrastructure construction and different quantities of matter, heat and electricity recovery and recycling. Results, calculated per unit mass of waste treated and per unit exergy delivered, under both multi-input and multi-output LCA perspectives, point out improved performance for scenarios characterized by increased matter and energy recovery. Although none of the investigated scenarios is capable to provide the best performance in all the analyzed impact categories, the scenario S-4 shows the best LCA results in the human toxicity and freshwater eutrophication categories, i.e. the ones with highest impacts in all waste management processes.

European trends in greenhouse gases emissions from integrated solid waste management

The European Union (EU) has 28 member states, each with very different characteristics (e.g. surface, population density, per capita gross domestic product, per capita municipal solid waste (MSW) production, MSW composition, MSW management options). In this paper several integrated waste management scenarios representative of the European situation have been generated and analysed in order to evaluate possible trends in the net emission of greenhouse gases and in the required landfill volume. The results demonstrate that an integrated system with a high level of separate collection, efficient energy recovery in waste-to-energy plants and very limited landfill disposal is the most effective according to the indices adopted. Moreover, it is evident that a fully integrated system can make MSW management a carbon sink with a potentiality of up to approximately 40 Mt CO2eq year(-1).

A review of technologies and performances of thermal treatment systems for energy recovery from waste

The aim of this work is to identify the current level of energy recovery through waste thermal treatment. The state of the art in energy recovery from waste was investigated, highlighting the differences for different types of thermal treatment, considering combustion/incineration, gasification and pyrolysis. Also different types of wastes - Municipal Solid Waste (MSW), Refuse Derived Fuel (RDF) or Solid Refuse Fuels (SRF) and some typologies of Industrial Waste (IW) (sludge, plastic scraps, etc.) - were included in the analysis. The investigation was carried out mainly reviewing papers, published in scientific journals and conferences, but also considering technical reports, to gather more information. In particular the goal of this review work was to synthesize studies in order to compare the values of energy conversion efficiencies measured or calculated for different types of thermal processes and different types of waste. It emerged that the dominant type of thermal treatment is incineration associated to energy recovery in a steam cycle. When waste gasification is applied, the produced syngas is generally combusted in a boiler to generate steam for energy recovery in a steam cycle. For both the possibilities--incineration or gasification--co-generation is the mean to improve energy recovery, especially for small scale plants. In the case of only electricity production, the achievable values are strongly dependent on the plant size: for large plant size, where advanced technical solutions can be applied and sustained from an economic point of view, net electric efficiency may reach values up to 30-31%. In small-medium plants, net electric efficiency is constrained by scale effect and remains at values around 20-24%. Other types of technical solutions--gasification with syngas use in internally fired devices, pyrolysis and plasma gasification--are less common or studied at pilot or demonstrative scale and, in any case, offer at present similar or lower levels of energy efficiency.

A comparative assessment of waste incinerators in the UK

The uptake in Europe of Energy from Waste (EfW) incinerator plants has increased rapidly in recent years. In the UK, 25 municipal waste incinerators with energy recovery are now in operation; however, their waste supply chains and business practices vary significantly. With over a hundred more plant developments being considered it is important to establish best business practices for ensuring efficient environmental and operational performance. By reviewing the 25 plants we identify four suitable case study plants to compare technologies (moving grate, fluidised bed and rotary kiln), plant economics and operations. Using data collected from annual reports and through interviews and site visits we provide recommendations for improving the supply chain for waste incinerators and highlight the current issues and challenges faced by the industry. We find that plants using moving grate have a high availability of 87-92%. However, compared to the fluidised bed and rotary kiln, quantities of bottom ash and emissions of hydrogen chloride and carbon monoxide are high. The uptake of integrated recycling practices, combined heat and power, and post incineration non-ferrous metal collections needs to be increased among EfW incinerators in the UK. We conclude that one of the major difficulties encountered by waste facilities is the appropriate selection of technology, capacity, site, waste suppliers and heat consumers. This study will be of particular value to EfW plant developers, government authorities and researchers working within the sector of waste management.

Effect of recycling activities on the heating value of solid waste: case study of the Greater Vancouver Regional District (Metro Vancouver)

Two main goals of the integrated solid waste management system (ISWMS) of Metro Vancouver (MV) include further recycling of waste and energy recovery via incineration of waste. These two very common goals, however, are not always compatible enough to fit in an ISWMS depending on waste characteristics and details of recycling programs. This study showed that recent recycling activities in MV have negatively affected the net heating value (NHV) of municipal solid waste (MSW) in this regional district. Results show that meeting MV's goal for additional recycling of MSW by 2015 will further reduce the NHV of waste, if additional recycling activities are solely focused on more extensive recycling of packaging materials (e.g. paper and plastic). It is concluded that 50% additional recycling of paper and plastic in MV will increase the overall recycling rate to 70% (as targeted by the MV for 2015) and result in more than 8% reduction in NHV of MSW. This reduction translates to up to 2.3 million Canadian dollar (CAD$) less revenue at a potential waste-to-energy (WTE) plant with 500 000 tonnes year(-1) capacity. Properly designed recycling programmes, however, can make this functional element of ISWMS compatible with green goals of energy recovery from waste. Herein an explanation of how communities can increase their recycling activities without affecting the feasibility of potential WTE projects is presented.