A review of energy recovery from waste in China

Tracking the carbon flows in municipal waste management in China

Municipal solid waste (MSW), a carbon-intensive waste stream, may create both instant and indirect impacts onto environmental and climate management. Despite multiple studies made for greenhouse gases (GHGs) emissions of municipal waste, this research aims to achieve a comprehensive assessment for the carbon cycle by exploring evolution of waste composition and temporal-spatial disparities in waste management. Carbon flows embodied in MSW have been estimated across 31 provinces in Mainland China in the period 2000-2018. This improved estimation could be 15-40% smaller than the conventional estimation employing a constant waste composition. Aggregately some 578 ± 117 megatonnes carbon (MtC) were contained in MSW, including 239 ± 60 Mt of fossil carbon and 339 ± 58 Mt of degradable organic carbon. After treatment, 299 ± 66 MtC were possibly deposited in landfills and dumps. 279 ± 51 MtC were released to the atmosphere, creating net GHGs emissions equivalent to1870 ± 334 megatonnes of CO2 (MtCO2e). MSW generation in China nearly doubled during the period, net GHGs emissions increased by 1.8×, whereas fossil carbon grew by a factor of 3.5, mainly propelled by an increasing content of waste plastic in MSW. More rapid growth was witnessed in provinces in southern China than in northern. Distinct spatial-temporal evolution of waste and carbon metabolism was driven by increment, composition, and management effects. In the long run, the increment and composition effects may drop off. Enhanced practices of waste management integrating the circular economy are needed to fully recycle carbon flows, minimize emissions, and manage carbon deposits in aging landfills and dumps.

Learning from the past to plan for the future: An historical review of the evolution of waste and resource management 1970-2020 and reflections on priorities 2020-2030 - The perspective of an involved witness

Improving waste and resource management (WaRM) around the world can halve the weight of plastics entering the oceans, significantly mitigate global heating and contribute directly to 12 of 17 sustainable development goals (SDGs). Achieving such results demands understanding and learning from historical evolution of WaRM. The baseline is 1970, prior to environmental legislation. Early steps in the Global North focused on the 'technical fix' within strictly enforced legal frameworks, first bringing hazardous wastes and municipal solid wastes (MSW) under control, then gradually ramping up environmental standards. Using modern technologies to the Global South often failed due to institutional and financial constraints. From 1990, focus switched to integrating technical and governance aspects: local institutional coherence, financial sustainability, provider inclusivity, user inclusivity, national legislative and policy framework. The Global North rediscovered recycling, using policy measures to promote segregation at source; this relied on new markets in emerging economies, which had largely disappeared by 2020. The Global South is making progress on bringing wastes under control, but around 2.7 billion people lack access to waste collection, while ~40% of collected MSW is open dumped or burned - a continuing global waste emergency. So, much remains to be done to move further towards a circular economy. Three policy priorities are critical for all countries: access to sustainable financing, rethinking sustainable recycling and worldwide extended producer responsibility with teeth. Extending services to unserved communities (SDG11.6.1) requires a people-centred approach, working with communities to provide both quality services and decent livelihoods for collection and recycling workers.

Pyrolysis: An effective technique for degradation of COVID-19 medical wastes

COVID-19 has led to the enormous rise of medical wastes throughout the world, and these have mainly been generated from hospitals, clinics, and other healthcare establishments. This creates an additional challenge in medical waste management, particularly in developing countries. Improper managing of medical waste may have serious public health issues and a significant impact on the environment. There are currently three disinfection technologies, namely incineration, chemical and physical processes, that are available to treat COVID-19 medical waste (CMW). This study focuses on thermochemical process, particularly pyrolysis process to treat the medical waste. Pyrolysis is a process that utilizes the thermal instability of organic components in medical waste to convert them into valuable products. Besides, the technique is environmentally friendly, more efficient and cost-effective, requires less landfill capacity, and causes lower pollution. The current pandemic situation generates a large amount of plastic medical wastes, which mainly consists of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and nylon. These plastic wastes can be converted into valuable energy products like oil, gas and char through pyrolysis process. This review provides detailed information about CMW handling, treatment, valuable product generation, and proper discharge into the open environment.

Suggested guidelines for emergency treatment of medical waste during COVID-19: Chinese experience

During the period of COVID-19, the medical waste disposal capacity is seriously inadequate. The main technical process of the municipal solid waste incineration system is the same as that of the medical waste incineration system. Under the conditions of optimizing the technological process, improving the supporting facilities, and controlling the co-processing ratio, the municipal solid waste incinerator (grate furnace) co-processing medical waste is feasible. Some suggested guidelines for emergency treatment of medical waste from COVID-19 have been provided by China.

Technical potential of electricity production from municipal solid waste disposed in the biggest cities in Brazil: landfill gas, biogas and thermal treatment

This article presents an analysis of possibilities for electrical energy production by using municipal solid waste disposed in the biggest Brazilian cities. Currently, the municipal solid waste in Brazil is collected and disposed of at landfills, but there are also other technologies, which in addition to dealing with the garbage can also provide benefits in terms of energy provision. The following scenarios were studied in this work: electricity production from landfill gas (reference scenario); incineration of all municipal solid waste; anaerobic digestion of organic waste and incineration of refuse-derived fuel fractions after being separated in separation plants. According to this study, the biggest cities in Brazil generate about 18.9 million tonnes of municipal solid waste per year (2011), of which 51.5% is biogenic matter. The overall domestic consumption of electricity is 480,120 GWh y(-1) in Brazil and the municipal solid waste incineration in the 16 largest cities in the country could replace 1.8% of it using incinerators. The city of São Paulo could produce 637 GWh y(-1) with landfill gas, 2368 GWh y(-1) with incineration of municipal solid waste and 1177 GWh y(-1) with incineration of refuse-derived fuel. The latter two scenarios could replace 27% and 13.5% of the residential electrical energy consumption in the city. This shows that thermal treatment might be a viable option of waste-to-energy in Brazil.

Optimization for municipal solid waste treatment based on energy consumption and contaminant emission

This paper analyzes the characterization of energy consumption and contaminant emissions from a municipal solid waste (MSW) treatment system that comprises transfer station, landfill site, combustion plant, composting plant, dejecta treatment station, and an integrated MSW treatment plant. The consumed energy and energy medium materials were integrated under comprehensive energy consumption (CEC) for comparison. Among typical MSW disposal methods such as combustion, composting, and landfilling, landfilling has the minimum CEC value. Installing an integrated treatment plant is the recommended MSW management method because of its lower CEC. Furthermore, this method is used to ensure process centralization. In landfill sites, a positive linear correlation was observed between the CEC and contaminant removal ratios when emitted pollutants have a certain weight coefficient. The process should utilize the minimum CEC value of 5.3702 kgce/t MSW and consider energy consumption, energy recovery, MSW components, and the equivalent of carbon dioxide emissions.

Design and quality assurance for solid recovered fuel

This contribution describes the processing and the quality assurance of solid recovered fuel (SRF) that is increasingly used in a wide range of co-incineration plants. As an example, the preparation of municipal, commercial and industrial wastes for recovering of two different specifications of waste fuels (i.e. primary burner fuel and hot disc fuel used in cement industry) is reported and the multiple stage processing scheme used in SRF production is presented as well as the quality of SRF obtained. It will be shown, that removing of metals and sorting out of unwanted inert materials like stones, glass and concrete only after disintegration of the waste matrix during several crushing and separation steps can be carried out efficiently. In the following chapters, the quality assurance of SRF is demonstrated and described by using two different scenarios (i.e. different sizes of waste streams with different particle sizes, delivered to a cement plant by walking floor trucks). Based on CEN/TS-guidelines for SRF as well as national norms (ÖNORM), two sampling procedures and sample preparation schemes are elaborated for the scenarios and own practical experiences in quality assessment of heterogeneous waste fuels are reported. Finally, references are given on new, innovative laboratory equipment like cutting mills with attached cyclones and a mobile, hand-sized XRF-instrument for fast identification of extraneous materials removed from the laboratory sample prior to chemical analysis.