Thermochemical conversion of waste into energy: a review

Technological advancements, environmental regulations, and emphasis on resource conservation and recovery have greatly reduced the environmental impacts of municipal solid waste (MSW) management, including emissions of greenhouse gases (GHGs). This study was conducted using a life-cycle methodology to track changes in GHG emissions during the past 25 years from the management of MSW in the United States. For the baseline year of 1974, MSW management consisted of limited recycling, combustion without energy recovery, and landfilling without gas collection or control. This was compared with data for 1980, 1990, and 1997, accounting for changes in MSW quantity, composition, management practices, and technology. Over time, the United States has moved toward increased recycling, composting, combustion (with energy recovery) and landfilling with gas recovery, control, and utilization. These changes were accounted for with historical data on MSW composition, quantities, management practices, and technological changes. Included in the analysis were the benefits of materials recycling and energy recovery to the extent that these displace virgin raw materials and fossil fuel electricity production, respectively. Carbon sinks associated with MSW management also were addressed. The results indicate that the MSW management actions taken by U.S. communities have significantly reduced potential GHG emissions despite an almost 2-fold increase in waste generation. GHG emissions from MSW management were estimated to be 36 million metric tons carbon equivalents (MMTCE) in 1974 and 8 MMTCE in 1997. If MSW were being managed today as it was in 1974, GHG emissions would be ~60 MMTCE.

The feasibility analysis of cement kiln as an MSW treatment infrastructure: From a life cycle environmental impact perspective

The key findings of a solid waste characterisation study conducted at the Guadalajara Metropolitan Zone, Mexico, are reported. Objectives of the study were to estimate the daily generation rate of household (HSW) and municipal solid waste (MSW), characterise and compare their composition by type of material, determine the proportion that HSW contributes to MSW, explore changes in MSW composition through time after final disposal, and estimate the types and amount of MSW that are sorted out for recycling at final disposal sites. HSW generated during seven days by a sample of 300 households chosen through a two-stage stratified sampling design was collected, weighed and classified. MSW entering the four local disposal sites was recorded for 12 weeks, and materials' sorting was quantified. MSW samples taken by excavating trenches in two final disposal sites were also characterised. The average per capita daily HSW generation rate was 508 g. HSW mainly consisted of putrescible waste (53%), paper (10%) and plastic (9%). The average daily generation rate of MSW was 3119.2 metric tonnes. HSW represented 55.9% of MSW, and the main difference between HSW and MSW was a lower proportion of organic materials (53% vs. 16.5%, respectively). The major changes in MSW composition through time after final disposal, were the result of the quick decomposition of putrescible materials. Only 2.2% of total MSW generated in Guadalajara (mainly package waste) was sorted for recycling.

Development of municipal solid waste management guidelines in biological crisis based on international experiences and considering local techno-economic characteristics

It is postulated that the current "garbage crisis" is due to a shortage of disposal capacity, not to burgeoning amounts of municipal solid waste (MSW). In support of this, trends in the quantity and composition of MSW, methods of waste reduction, recycling and growth of waste-to-energy capacity are examined to gain insight as to the future course of MSW management in the U.S. over about the next 15 plus years. This is the likely time to install new disposal capacity if pending legislative proposals are passed, that would enable states that provide their own disposal to ban wastes from other states. A new term, the "intensity of waste generation", is proposed and illustrated, analogous to the intensity of mineral usage. The intensity is decreasing, implying that it is unlikely that waste generation will grow at rates projected by extrapolation or simple macroeconomic assumptions. Some other conclusions are: per capita MSW generation was nearly statistically constant from 1970 to 1984; the content of most forms of packaging in MSW are decreasing; packaging decreases the amount of food residues in MSW; and proposed national recycling targets of about 25% or more are not likely to be achieved, in part because of changes in the composition of MSW. Coupled with likely shortages of labor to process separated waste, it is forecast that there will be some future time when people will not think source separation is worth the bother and recycling will decrease. The future growth of waste-to-energy capacity is projected by assuming that a city will install capacity when others have done so, which leads to a simple quantitative model. The likely effects of impending landfill and incineration regulations are addressed.

The objective of this study was investigated the potential of municipal solid waste (MSW) to produce refuse-derived fuel from Bangkok municipality. The composition, heating value and proximately content were analyzed. The amount of MSW in Bangkok generated was approximately 4.86 million tons or 13,327 tons/day in 2017. About 79.5% was disposed by landfill and 20.5% was recycled. The compositions of MSW were biodegradable (49.58%), combustible (36.32%) and non-combustible (14.10%) wastes. Moisture content was 59.5±8.6% (as received), volatile matter, fixed carbon and ash were 72.4±3.2%, 8.2±0.5% and 19.4±0.5% (as dry basis), respectively. Heating value was 20.03±0.52 MJ/kg. These results indicated that MSW from Bangkok municipality is potential to produce the refuse-derived fuel. To reduce the environmental impacts as well as energy recovery, the MSW might be alternative sources of renewable energy in the future.

Increasing amount of Municipal solid waste (MSW) is gradually getting serious problem which human has to be faced. Tradition waste classification mechanisms and devices are too complicated and lack of accuracy. In this paper, we propose a preliminary study to apply microwave nondestructive testing technique on MSW classification. Experiment conducted in this study using microwave (300MHz) nondestructive testing technique demonstrated that vertical incidence of plane wave between air and different composition of MSW generates different reflection coefficients. The experiment also shows that metal has the highest reflection coefficient while wood and leaf have the least reflection in various compositions of MSW. The other compositions of MSW listed in this paper have tiny difference in reflection coefficient. The results of the experiment shown in this study provide a new thinking for MSW classification.

Use of municipal solid waste (MSW) as fuel for electricity generation reduces landfill disposal and can mitigate air quality degradation associated with combustion of conventional fossil fuels. Co-combustion is a waste-to-energy technology that can use MSW and coal as co-fuels, offering potential energy recovery and reduced air emissions. This research discerns how MSW composition influences the heating value and air pollution for the co-combustion of coal with MSW using five MSW composition scenarios, four of which were derived by a reduction of plastics, organics, paper, or a combination thereof, as compared to the national average MSW composition. Numerous combustion products could be evaluated; this study focused on five high impact air combustion products: SO2, CO, CO2, NO, and NO2. The moisture content was varied from ∼10% (considered dry) to 40% (average MSW moisture). AspenPlus software was used for the deterministic simulation modeling of incineration (MSW only) and parallel co-firing (co-combustion of coal and MSW) to determine theoretical heating values and pollutant effluent concentrations. The United States Environmental Protection Agency (U.S. EPA) models WAR and WARM were used to determine the potential environmental impacts (PEIs) and greenhouse gas emission equivalencies, respectively, for each MSW scenario. For the WAR model, values for each impact category parameter can vary, but each parameter is weighed equally. Of the MSW scenarios studied, the national average held the highest heating value with 8519 MBtu/lb and the lowest occurred for the MSW scenario with recycled paper and composted organics, with 8251 MBtu/lb. Results show that SO2, CO, CO2, NO, and NO2 flue gas concentrations (and therefore PEIs) depend upon the composition and moisture of the MSW, in addition to the MSW/coal ratio. Approximate ranges for the WAR results (PEI/h) are 7410–7663 for NO, 4–8 for NO2, 18–105 for CO, 30–46 for CO2, and 89–2152 for SO2. WARM results show lower net CO2 emission equivalents to landfill MSW with reduced paper and organics, while combustion is preferred for MSW with paper reduction, organics reduction, and plastics reduction. The results for the national average MSW were independent of the disposal processing method. Reduction in pollutant concentrations did not yield overall cost savings for the electricity producer, as profit was reduced by ∼20–30%. There are savings associated with emission costs using MSW in lieu of coal: up to ∼3.3% for NO, ∼20–47% for NO2, and ∼95% for SO2. A hypothetical carbon dioxide tax was also imposed to realize the potential cost savings by reducing CO2 emissions. In summary, the measurable impact MSW composition and moisture had on pollutant concentration, heating value, and economic parameters was important.

The future course of solid waste management in the U.S.

Modern management of waste around the world has moved from waste disposal to energy recovery through WtE. Technologies that can be utilized to recover energy from MSW via thermal conversion processes such as incineration, gasification, pyrolysis, biochemical conversion processes and chemical conversion. The aim of this research was to evaluate the heating (calorific) value of municipal wet solid waste from Kabagarame dumping site in Bushenyi District, Uganda. Wet solid waste samples were analyzed, the heating value of the wastes were evaluated. The results showed that other organics had the highest calorific value of 26.22 MJ/kg, followed by paper 16.60 MJ/kg, followed by food waste 16.51MJ/kg and then wood 16.14 MJ/kg on dry matter basis. The results on the heating value on wet basis showed that other organics had the highest calorific value of 12.82 MJ/kg, followed by paper 14.04 MJ/kg, followed by food waste 13.66 MJ/kg and then wood 9.89 MJ/kg. The heating value of plastics was not obtained since they are recovered from the dumping site and recycled. This energy can be harnessed by different production facilities particularly Tea factories in the region through incineration process so as to generate heat necessary for their production processes. In conclusion, results from this research also suggest that understanding the composition of municipal solid waste is essential for creating the best disposal strategy, so that recovering resources trapped in the wastes can be optimized. It is therefore necessary that energy derived from municipal solid wastes can be taken into account in the national energy budget. Keywords: Heating value, solid waste, Kabagarame and dumping site.

Analyzing the impact of age on waste properties at an open dumpsite in Khulna

Municipal solid waste (MSW) severely threatens human health and the ecological environment owing to its toxicity, mutagenic activity and carcinogenicity. The continuous increase in MSW together with stringent regulations makes sanitary disposal imperative. Waste sorting and recycling has been recognized as an efficient and economical treatment strategy. By analysing research data from 31 provinces between 2000 and 2017, the overarching goal of this work was to determine the characterizations and the compositions of MSW in China and then provide advices for sorting, transporting, storing and disposing of MSW. The results showed that the amount of MSW that was generated ranged from 0.08 to 2.34 kg d−1 ca−1 and averaged 0.73 kg d−1 ca−1 in China. The average bulk density, moisture content and the wet basis of the low calorific value of the MSW were 325 kg m−3, 50.3% and 4649 kcal kg−1. The MSW in China could be classified into four main categories, food waste, recycling waste, landfill waste and hazardous substances, and could be further classified into ten sub-categories. Overall, food waste was the most common and could be best managed via compost production. Bulk density was highly positively correlated with the ratio of the dust and bricks in all MSW and highly negatively correlated with the ratio of the food waste, metal, glass, plastic and rubber. The wet basis of the low calorific value was highly positively correlated with the ratio of the plastic and rubber, and the water content was highly positively correlated with the ratio of the food waste. Temporally, most of the components, especially waste paper and plastics, increased, while wood, dust and bricks decreased.Graphic abstract

The constant generation of Municipal Solid Waste (MSW) is a global concern in terms of quantity and its variety. The composition of MSW is influenced by the level of income; the season of the year; population; culture and lifestyle of people living in that community. Nigeria, in particular, is currently struggling with the menace of the upsurge in the quantity MSW in her major cities, but concern only with its collection, transportation, and disposal, however neglecting the prospect of material recovery from MSW for recycling. On this note, the study aimed to characterize MSW from identified dumpsites and at household level in Abuja Municipal Area Council (AMAC) and Bwari area council, Abuja, Nigeria towards a sustainable and efficient MSW management. The methodology used in this study was carried out in both wet and dry seasons, and each season entails; the use of American Standard Test Method [1] to determine the composition of unprocessed MSW at dumpsites 3 days in a week for 4 weeks and, the segregation of MSW into colored bags representing waste category at the household level was done for 2 weeks. The use of a stratified and random sampling method was employed to administer the questionnaires for data acquisition. The results show that the level of income played a significant role in the constituents of MSW generated at district level. In conclusion, food waste/organics and plastic waste are the predominant MSW categories in AMAC, and Bwari area council, Abuja, Nigeria. The characterization of MSW is essential for a long-term effect and sustainable solid waste management plans in order to design an appropriate and efficient waste management system for the society.

With the fast development of economy, enhancement of people's standard of living, increasing of urban population and speedup of urbanization, the generation of municipal solid waste (MSW) has heavily risen, the elements of MSW have changed. This not only brings a great harm on urban environment, but also hinders urban economic growth. My paper first time quotes source separation MSW collection system in Shenyang, controlling the quality of MSW from source, it is very crucial for the disposal and synthetic utilization to build MSW sorting collection system in order to reduce the quantity of MSW. In this paper, author researches source separation quality of BMW, investigating the quantity and composition of MSW, BMW and RMW by two collection techniques in Shenyang.

Recently, most cities in Vietnam are facing waste problems that are mainly caused by the rapid increase of municipal solid waste (MSW) amount and the limitations of the MSW management system. This study aims to characterise the waste generation, composition and characteristics of MSW in Da Nang city, which is one of the five biggest cities in Vietnam. The current problems and challenges of MSW system are also analysed. The sampling survey was conducted in the dry and wet seasons in August and November 2018. The MSW was taken directly from trucks at the landfill site with the sample size by 500 kg/waste sources. This study shows that the simultaneous development of production, trade and service activities in the last decade has led to the speedy growth of waste by 9 %/y, and reached 1,073 t/d in 2018. In which, waste generated from industry and the hospitals account inconsiderable proportions by 3.9 % and 1.4 %. This study also indicated that the MSW generation rate from the urban areas is more than that of the coastal and industrial areas. For the composition of MSW, biodegradable waste and recyclables are the main components with the proportion of 54 % and 27 % of the total waste. While the waste composition almost do not differ considerably by seasons, the difference in the characteristics of waste is a consideration for the processing. The current problems and solutions to improve the MSW system toward sustainability are also discussed and suggested.