Solid Waste Components Research Articles

Characterization of selected municipal solid waste components to estimate their biodegradability

Biological treatments of Residual Municipal Solid Waste (RMSW) allow to divert biodegradable materials from landfilling and recover valuable alternative resources. The biodegradability of the waste components needs however to be assessed in order to design the bioprocesses properly. The present study investigated complementary approaches to aerobic and anaerobic biotests for a more rapid evaluation. A representative sample of residual MSW was collected from a Mechanical Biological Treatment (MBT) plant and sorted out into 13 fractions according to the French standard procedure MODECOM™. The different fractions were analyzed for organic matter content, leaching behavior, contents in biochemical constituents (determined by Van Soest's acid detergent fiber method), Biochemical Oxygen Demand (BOD) and Bio-Methane Potential (BMP). Experimental data were statistically treated by Principal Components Analysis (PCA). Cumulative oxygen consumption from BOD tests and cumulative methane production from BMP tests were found to be positively correlated in all waste fractions. No correlation was observed between the results from BOD or BMP bioassays and the contents in cellulose-like, hemicelluloses-like or labile organic compounds. No correlation was observed either with the results from leaching tests (Soluble COD). The contents in lignin-like compounds, evaluated as the non-extracted RES fraction in Van Soest's method, was found however to impact negatively the biodegradability assessed by BOD or BMP tests. Since cellulose, hemicelluloses and lignin are the polymers responsible for the structuration of lignocellulosic complexes, it was concluded that the structural organization of the organic matter in the different waste fractions was more determinant on biodegradability than the respective contents in individual biopolymers.

THERMODYNAMIC MODELING OF SOLID FUEL COMBUSTIBLE WEIGHT GASIFICATION PROCESSES

As a model of unconventional fuels combustible mass composition and properties, averages of municipal solid waste (MSW), components of their morphological structure and their derivatives RDF, SRF Ukrainian origin and different world regions are selected. The reference data array: adiabatic equilibrium products state indicators of oxygen and steam-oxygen gasification of municipal solid waste components morphological composition, averages combustible mass of solid waste MSW, RDF, SRF for a given equilibrium parameters: T = 298.15 K, p = 0.1 MPa, depending on the ratio of «combustible mass : oxidant mass» is calculated. Coefficient a value for different by Qнр solid waste groups and other low grade fuels optimally gasification mode is determined. Bibl. 22, Fig. 3, Tab. 9.

Key parameters for behaviour related to source separation of household organic waste: A case study in Hanoi, Vietnam.

Proper management of food waste, a major component of municipal solid waste (MSW), is needed, especially in developing Asian countries where most MSW is disposed of in landfill sites without any pretreatment. Source separation can contribute to solving problems derived from the disposal of food waste. An organic waste source separation and collection programme has been operated in model areas in Hanoi, Vietnam, since 2007. This study proposed three key parameters (participation rate, proper separation rate and proper discharge rate) for behaviour related to source separation of household organic waste, and monitored the progress of the programme based on the physical composition of household waste sampled from 558 households in model programme areas of Hanoi. The results showed that 13.8% of 558 households separated organic waste, and 33.0% discharged mixed (unseparated) waste improperly. About 41.5% (by weight) of the waste collected as organic waste was contaminated by inorganic waste, and one-third of the waste disposed of as organic waste by separators was inorganic waste. We proposed six hypothetical future household behaviour scenarios to help local officials identify a final or midterm goal for the programme. We also suggested that the city government take further actions to increase the number of people participating in separating organic waste, improve the accuracy of separation and prevent non-separators from discharging mixed waste improperly.

The Application of Fungi for Bioleaching of Municipal Solid Wastes for the Production of Environmental Acceptable Compost Production

Analysis of the chemical components of Municipal solid waste (MSW) indicated that the presence of high concentrations of toxic heavy metals. The aim of this study was to select the best leaching condition, in order to generate a compost product, which adheres to the environmental standards for safe use. To determine the role of organic acids produced in the bioleaching process, chemical leaching experiments were compared using inorganic (H2SO4) or organic acids (oxalic, and gluconic acids). These results revealed that addition of H2SO4 correlated with a lower retained yield when comparing with addition of the other acids. Bioleaching was then studied by culturing fungi on the MSW. Addition of Aspergillus niger correlated with an efficient removal of heavy metal elements. The effect of pH was also determined and assays at pH 5.5 using a clay medium (32.4%) or at pH 2.5 using a sorghum medium (28%) were characterised by a lower retained yield. In the above conditions, we looked at elemental ions which have been deemed beneficial to the environment (P and K) and those which are toxic (Cd, Cu,Cr, Ni, Pb and Zn), these elements were measured in the solid fractions.

Classification of hazardous compound of municipal solid waste as a basis of its treatment system formation in regions of Ukraine

Ensuring the sanitary and biological well-being of the country is one of the most important aspects of national security in terms of public health. Hygienic problems caused by pollution of the territory of settlements by waste from production and consumption remain among the priority ones. Purpose. The development of hazardous compound of municipal solid waste classification, which is the precondition of its treatment system in regions of Ukraine. Methods. Critical analysis of the existing provisions on the principles of hazardous compound of municipal solid waste classification and the approaches to treatment of their flows. Results. Classifications of individual components of the hazardous compound in municipal solid waste (medical waste and waste of electrical and electronic equipment) have been proposed. Ensuring ecological well-being in the regions of Ukraine largely depends on the efficiency of the functioning of the system of dealing with hazardous components of Solid Waste in general and with medical waste in particular. The first step in creating a system for handling medical waste is their classification. We have developed a classification of medical waste, in which all of them are divided into three main categories: waste of veterinary clinics (polyclinic); Wastes of humanitarian treatment and prophylaxis establishments, waste of the communal sectorctor For the first time in the classification of medical waste, waste from veterinary clinics was taken into account. Conclusions. The developed classifications of the components of the hazardous compound flow of municipal solid waste, as well as the principles of their use in the sphere of solid waste management, help to prevent the negative impact of these wastes on the environment and transfer a significant part of them to the state of secondary material resources.

Solid Waste Management Challenges in Urban Areas of Ghana: A Case Study of Bawku Municipality

This study was conducted in the Bawku Municipality of the Upper East, Ghana, with the view to assessing the factors that impede the management of solid waste. Questionnaires were submitted to 150 randomly selected households, while face-to-face semi-structured interviews were conducted with the municipal Waste Management Department and a private waste management company, Zoomlion Ghana Ltd. Data collected included components of solid waste generated, waste collection, transportation and final disposal methods, the challenges confronting waste management institutions, and respondents' knowledge and perceptions of the waste management system and their attitudes towards it. Components of wastes generated were organic waste, paper waste and plastics. Factors that adversely affected waste collection and transportation systems were the inadequate supply of waste collection containers, the existence of a weak waste transportation system and a low patronage of the door-to-door collection method. The study showed that the municipal landfill did not meet the required standard. The results also revealed the lack of public awareness on issues regarding waste and lack of a participatory approach that makes the people an active stakeholder in the waste management system. This situation accounted for indiscriminate disposals of waste by most respondents who viewed the issue of waste management as the exclusive responsibility of the local government. The study further showed that the waste management institutions were faced with financial difficulties, understaffing and poor logistics and nature of roads, and social constraints. The study therefore suggests the development of a strategic plan for efficient waste management which revolves around these findings.

Environmental Sanitation Practices: A Case Study of Solid Waste Management in Semi-Urban Communities in Orlu, Imo State Nigeria

Background: Environmental sanitation is a fundamental process that is a key public health intervention which is essential for social, economic and overall health development of communities. Objective: To determine Knowledge, Attitude and Practices of Environmental Sanitation in Semi-Urban Communities in Orlu, Imo State, Nigeria. Methods: A cross sectional descriptive design using a multistage random sampling technique to select 426 participants from households and business premises in semi-urban communities in Orlu Local Government Area of Imo State. Data was collected using a pretested, semi structured, interviewer administered questionnaire. Descriptive analyses were done with frequencies and summary statistics to assess the respondents’ knowledge, attitude and practices of environmental sanitation. Results: The results revealed that the mean age of the respondents’ was 37.0 ± 2.2 with a male to female ratio of 1:1.2. Despite high awareness about environmental sanitation (95.0%) reported among the respondents, proportion of them with good knowledge about environmental sanitation (22.9%), attitude (38.6%) and practice (20.8%) towards environmental sanitation was low. The mean quantity of waste generated per week per household or business premise was 14.1 ± 0.94 kg with a majority of the respondents (80.0%), not separating their waste before disposal. The commonest solid waste component generated was organic/perishable materials (74.8%) and the commonest disposal practice reported was open dumping (49.8%). Conclusion: A lot of attention is still required in the development of basic sanitation infrastructure and also, in the promotion of strategies or interventions that influence behavioural change towards environmental sanitation especially in developing countries like Nigeria.

Continuous, self-sustaining smouldering destruction of simulated faeces

A new approach for the rapid destruction of human waste using smouldering combustion is presented. Recently, self-sustaining smouldering combustion was shown to destroy the organic component of simulated human solid waste and dog faeces resulting in the sanitization of all pathogens using a batch process (Yermán et al., 2015). Here, a continuous smouldering process is demonstrated for the first time, allowing for a much smaller reactor size and much less energy input per mass of waste treated. The self-sustained smouldering of simulated human faeces mixed with sand is evaluated over long periods (more than 16h) based on a single ignition. The key process of intermittent self-sustained smouldering, in which the reaction is terminated and restarted by only turning the air off and on, is demonstrated. Experiments examine the influence of two key operator controls: airflow rate and set elevation of the quasi-steady-state smouldering front in a 37cm high reactor. Quasi-steady-state fuel destruction rates from 93g/h to 12g/h were achieved by varying the superficial flow velocity from 7.4cm/s to 0.11cm/s, the latter with a velocity approximately an order of magnitude lower than possible for a self-sustaining reaction in an equivalent batch system. Excess energy of up to 140J/g of sand was recovered from the clean sand produced in each cycle, which could be used to further increase the energy efficiency of this novel waste treatment system.

Municipal Solid Waste Characterization According to Different Income Levels: A Case Study

Solid waste generation and characterization are some of the most important parameters which affect environmental sustainability. Municipal solid waste (MSW) characterization depends on social structure and income levels. This study aims to determine the variations in waste components within MSW mass by income levels and seasonal conditions following the analysis conducted on the characterization of solid wastes produced in the Kartal district of the province of Istanbul, which is the research area of this study. To this end, 1.9 tons of solid waste samples were collected to represent four different lifestyles (high, medium, and low income levels, and downtown) in the winter and summer periods, and characterization was made on these samples. In order to support waste characterization, humidity content and calorific value analyses were also conducted and various suggestions were brought towards waste management in line with the obtained findings. According to the results obtained in the study, organic waste had the highest rate of waste mass by 57.69%. Additionally, significant differences were found in municipal solid waste components (MSWC) based on income level. Average moisture content (MC) of solid waste samples was 71.1% in moisture analyses. The average of calorific (heating) value (HHV) was calculated as 2518.5 kcal·kg−1.

Evaluation of the adsorption potential of eco-friendly activated carbon prepared from cherry kernels for the removal of Pb2+, Cd2+ and Ni2+ from aqueous wastes

Development, characterization and evaluation of the efficiency of cost-effective medium for the removal of Pb2+, Cd2+ and Ni2+ from aqueous systems, as a novel, eco-friendly solution for wastewater remediation were done. The precursors for low-cost adsorbent were lignocellulosic raw materials (sweet/sour cherry kernels), as industrial byproducts and components of organic solid waste. Activated carbon synthesis was carried out by thermochemical conversion (H3PO4, 500 °C) in the complete absence of inert atmosphere. Characterization of the activated carbon was performed by elemental analysis, FTIR, SEM, EDX and BET. BET surface area corresponds to 657.1 m2 g−1. The evaluation also included the influence of pH, contact time, solute concentration and adsorbent dose on the separation efficiency in the batch operational mode. The equilibrium and kinetic studies of adsorption were done. The maximum adsorption capacity of the activated carbon for Cd2+ ions was calculated from the Langmuir isotherm and found to be 198.7 mg g−1. Adsorption of Pb2+ and Ni2+ were better suitable to Freundlich model with the maximum adsorption capacity of 180.3 mg g−1 and 76.27 mg g−1, respectively. The results indicate that the pseudo-second-order model best describes adsorption kinetic data. Based on desorption study results, activated carbon was successfully regenerated with HNO3 for 3 cycles. In order to provide the results for basic cost-effective analysis, competing ion-effects in a real sample have been evaluated.

The CO2 gasification reactivity of chars produced from Australian municipal solid waste

Technical risk and unfavourable project economics are often touted as barriers to successful waste-to-energy systems. Understanding feedstock behaviour, and how this impacts technology selection and operation, is a key aspect to addressing the technical risk component. In gasification systems, feedstock reactivity to CO2 is one of the factors that are known to contribute significantly to feedstock behaviour. In this work, the reactivities of char samples from components of municipal solid waste (MSW) to CO2 were characterised as part of a wider study into gasification behaviour of waste streams. As expected, gasification rates of wood waste and garden waste chars are comparable to those from other biomass fuels. The least reactive chars were found to be those produced from textiles and printing papers. There were two orders of magnitude differences in the rates of the least reactive and most reactive components, which has significance for our understanding of how the composition of the material in a waste gasifier changes with time. Furthermore, we demonstrated a good closure between calculated rates (based on properties of individual components) and rates measured for the entire MSW sample. This shows that this study has a broader applicability, and could be extended to estimate the gasification behaviour of MSW streams of different compositions in a range of gasification technologies.

Resource and Greenhouse Gas Assessments of the Thermochemical Conversion of Municipal Solid Waste in Mexico

The use of components in municipal solid waste (MSW) as feedstock for liquid transportation biofuels and chemicals can be a sustainable solution for energy needs while minimizing impacts of landfills on the environment. This study conducts a resource assessment for available MSW in Mexico and concludes that when the organic and polyolefin plastic components are converted to liquid hydrocarbon transportation biofuels through a pyrolysis-based pathway, up to 7% of Mexico’s transportation-fuel consumption needs could be met. A preliminary carbon footprint analysis (CFA) using stage-specific emission factors from the literature shows that liquid transportation biofuels from the organic portion of MSW (paper, packaging, wood, yard trimmings) sequesters 9.5 g CO2 eq per MJ biofuel, with significant pathway credits due to avoiding landfill CH4 emissions. The greenhouse gas (GHG) emissions from the conversion of the polyolefin plastic in the MSW are positive (88 g CO2 eq per MJ), though still lower than current f...

Pyrolysis and combustion of municipal solid wastes: Evaluation of synergistic effects using TGA-MS

A thermogravimetric methodology was developed to investigate and semi-quantify the extent of synergistic effects during pyrolysis and combustion of municipal solid waste (MSW). Results from TGA-MS were used to compare the pyrolysis and combustion characteristics of single municipal solid waste components (polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), branches (BR), leaves (LV), grass (GR), packaging paper (PK), hygienic paper (HP) and cardboard (CB)) and a mixture (MX) of PP, BR and CB. Samples were heated under dynamic conditions at 20°C/min from 25°C to 1000°C with the continuous record of their main evolved fragments. Synergistic effects were evaluated by comparing experimental and calculated weight losses and relative areas of MS peaks. Pyrolysis of the mixture happened in two stages, with the release of H2, CH4, H2O, CO and CO2 between 200 and 415°C and the release of CH4, CxHy, CO and CO2 between 415 and 525°C. Negative synergistic effect in the 1st stage was attributed to the presence of PP where the release of hydrocarbons and CO2 from BR and CB was inhibited, whereas positive synergistic effects were observed during the 2nd degradation stage. In a second part of the study, synergistic effects were related to the dependency of the effective activation energy (Eα) versus the conversion (α). Higher Eαs were obtained for MX during its 1st stage of pyrolysis and lower Eαs for the 2nd stage when compared to the individual components. On the other hand, mostly positive synergistic effects were observed during the combustion of the same mixture, for which lower Eαs were recorded.

Thermogravimetric and calorimetric characteristics during co-pyrolysis of municipal solid waste components

The thermogravimetric and calorimetric characteristics during pyrolysis of wood, paper, textile and polyethylene terephthalate (PET) plastic in municipal solid wastes (MSW), and co-pyrolysis of biomass-derived and plastic components with and without torrefaction were investigated. The active pyrolysis of the PET plastic occurred at a much higher temperature range between 360°C and 480°C than 220–380°C for the biomass derived components. The plastic pyrolyzed at a heating rate of 10°C/min had the highest maximum weight loss rate of 18.5wt%/min occurred at 420°C, followed by 10.8wt%/min at 340°C for both paper and textile, and 9.9wt%/min at 360°C for wood. At the end of the active pyrolysis stage, the final mass of paper, wood, textile and PET was 28.77%, 26.78%, 21.62% and 18.31%, respectively. During pyrolysis of individual MSW components at 500°C, the wood required the least amount of heat at 665.2J/g, compared to 2483.2J/g for textile, 2059.4J/g for paper and 2256.1J/g for PET plastic. The PET plastic had much higher activation energy of 181.86kJ/mol, compared to 41.47kJ/mol for wood, 50.01kJ/mol for paper and 36.65kJ/mol for textile during pyrolysis at a heating rate of 10°C/min. H2O and H2 peaks were observed on the MS curves for the pyrolysis of three biomass-derived materials but there was no obvious H2O and H2 peaks on the MS curves of PET plastic. There was a significant interaction between biomass and PET plastic during co-pyrolysis if the biomass fraction was dominant. The amount of heat required for the co-pyrolysis of the biomass and plastic mixture increased with the increase of plastic mass fraction in the mixture. Torrefaction at a proper temperature and time could improve the grindability of PET plastic. The increase of torrefaction temperature and time did not affect the temperature where the maximum pyrolytic rates occurred for both biomass and plastic but decreased the maximum pyrolysis rate of biomass and increased the maximum pyrolysis rate of PET plastic. The amount of heat for the pyrolysis of biomass and PET mixture co-torrefied at 280°C for 30min was 4365J/g at 500°C, compared to 1138J/g for the pyrolysis of raw 50% wood and 50% PET mixture at the same condition.

Targeted modification of organic components of municipal solid waste by short-term pre-aeration and its enhancement on anaerobic degradation in simulated landfill bioreactors

Pre-aeration is effective on regulating subsequent anaerobic degradation of municipal solid waste (MSW) with high organic fractions during landfilling. The strength of pre-aeration should be optimized to intentionally remove some easily biodegradable fractions while conserve bio-methane potential as much as possible. This study investigates the evolution of organic components in MSW during 2–14days pre-aeration process and its impacts on subsequent anaerobic degradation in simulated landfill bioreactors. Results showed that a 6-day pre-aeration enabled to develop a thermophilic stage, which significantly accelerated biodegradation of organics except lignocelluloses, with removal rates of 42.8%, 76.7% and 25.1% for proteins, carbohydrates and lipids, respectively. Particularly, ammonia from accelerated ammonification in the thermophilic stage neutralized VFAs generated from anaerobic landfilling. As a result, the MSW with 6-day pre-aeration obtained the highest methane yield 123.4NL/kg dry matter. Therefore, it is recommended to interrupt pre-aeration before its cooling stage to switch to anaerobic landfilling.

Supercritical water gasification of RDF and its components over RuO2/γ-Al2O3 catalyst: New insights into RuO2 catalytic reaction mechanisms

Five samples including a composite refuse derived fuel (RDF) and four combustible components of municipal solid wastes (MSW) have been reacted under supercritical water conditions in a batch reactor. The reactions have been carried out at 450°C for 60min reaction time, with or without 20wt% RuO2/gamma-alumina catalyst. The reactivities of the samples depended on their compositions; with the plastic-rich samples, RDF and mixed waste plastics (MWP), giving similar product yields and compositions, while the biogenic samples including mixed waste wood (MWW) and textile waste (TXT) also gave similar reaction products. The use of the heterogeneous ruthenium-based catalyst gave carbon gasification efficiencies (CGE) of up to 99wt%, which was up by at least 83% compared to the non-catalytic tests. In the presence of RuO2 catalyst, methane, hydrogen and carbon dioxide became the dominant gas products for all five samples. The higher heating values (HHV) of the gas products increased at least two-fold in the presence of the catalyst compared to non-catalytic tests. Results show that the ruthenium-based catalyst was active in feedstock steam reforming, methanation and possible direct hydrogenolysis of C–C bonds. This work provides new insights into the catalytic mechanisms of RuO2 during SCWG of carbonaceous materials, along with the possibility of producing high yields of methane from MSW fractions.

A rapid method for analysis of radioactive waste for the presence of fuel matrix components

The presence of large amounts of 137Cs and 90Sr radionuclides in radioactive waste severely complicates its analysis for the presence of fuel matrix components. Labor-consuming procedures for determining uranium and plutonium radionuclides in soils and water are hardly applicable in this case. A rapid method based on these procedures was developed for determining fuel matrix components in both liquid and solid radioactive waste. The procedure was tested in the course of works on dismantling the MR reactor of the National Research Centre Kurchatov Institute. Samples of water, bottom slime, and deposits on the walls of ponds in the central room of the MR reactor and of deposits from the dismantled active drain system were analyzed.

The application of prepared porous carbon materials: Effect of different components on the heavy metal adsorption.

In this study, five typical municipal solid waste (MSW) components (tyres, cardboard, polyvinyl chloride (PVC), acrylic textile, toilet paper) were used as raw materials to prepare four kinds of MSW-based carbon materials (paperboard-based carbon materials (AC1); the tyres and paperboard-based carbon materials (AC2); the tyres, paperboard and PVC-based carbon materials (AC3); the tyres, paperboard, toilet paper, PVC and acrylic textile-based carbon materials (AC4)) by the KOH activation method. The characteristic results illustrate that the prepared carbon adsorbents exhibited a large pore volume, high surface area and sufficient oxygen functional groups. Furthermore, the application of AC1, AC2, AC3, AC4 on different heavy metal (Cu(2+), Zn(2+), Pb(2+), Cr(3+)) removals was explored to investigate their adsorption properties. The effects of reaction time, pH, temperature and adsorbent dosage on the adsorption capability of heavy metals were investigated. Comparisons of heavy metal adsorption on carbon of different components were carried out. Among the four samples, AC1 exhibits the highest adsorption capacity for Cu(2+); the highest adsorption capacities of Pb(2+) and Zn(2+) are obtained for AC2; that of Cr(3+) are obtained for AC4. In addition, the carbon materials exhibit better adsorption capability of Cu(2+) and Pb(2+) than the other two kind of metal ions (Zn(2+) and Cr(3+)).

دراسة واقع ادارة المخلفات الصلبة لمدينة بعقوبة

يهدف البحث الى د ا رسة واقع ادارة المخلفات الصلبة المنزلية في مدينة بعقوبة ووضع حلول لمشكلة النفايات في المدينة وقد ركزت هذه الد ا رسة على الم ا رحل الاولى في الادارة الا وهي حساب وتقدير كمية النفايات الصلبة المنزلية المتولدة ومعرفة النسب المئوية لمكونات المخلفات الصلبة. ولاجل تحقيق هذا الهدف تم إج ا رء المسح الميداني لتحديد تركيب ومعدل انتاج النفايات الصلبة المنزلية لمجموعة من الاسر التي تم انتخابها من احياء مدينة بعقوبة. أظهرت النتائج ان معدل انتاج الفضلات الصلبة المنزلية ) 516 , 1 كغم/فرد( لمدينة بعقوبة. كما بينت الد ا رسة ان اعلى معدل انتاج للفضلات المنزلية كان في فصل الصيف ) 12 , 1كغم/فرد( وبلغ اقل معدل انتاج للفضلات المنزلية في فصل الشتاء 1566( , 1 كغم/فرد(. وينتج من النفايات المنزلية لمدينة بعقوبة فقط حوالي 16 , 2 طن يومي من الورق ومن البلاستك 5 , % 12 طن وغيرها من المواد الاخرى بلاضافة للمواد العضوية التي ممكن الاستفادة منها كمواد محسنة للتربة، اي 63 من النفايات يمكن الاستفادة منها والمتبقي 26 % يدفن في المطمر. The research aims to study the solid waste management in Baquba, and develop solutions for the problem of waste in the city. This study focuses on the early stages of the solid waste management that includes assessment of the solid waste components and the percentages of the components. A questionnaire survey was used to collect data from different groups of families from Baquba. The results showed that the rate of production of household solid waste was (0.615 kg/person/day). The study also demonstrated that the highest rate of production of household waste was in the summer (1.12 kg/person/day), where the rate of production of household waste in the winter was (0.1675 kg/person/day). Produces of household waste to the city of Baquba, only about 17.2 tons of paper daily and 12.6 tons of plastic and other materials Other .Organic matter which constituted) 50%) can be using to produce soil conditioners. Recycled and reused matters comprised( 23%) could also be advantageously used. The remaining small percentages which amounted ( 27%) could be sent to landfill.

Greenhouse gas emissions from solid waste in Beijing: The rising trend and the mitigation effects by management improvements.

Disposal of solid waste poses great challenges to city managements. Changes in solid waste composition and disposal methods, along with urbanisation, can certainly affect greenhouse gas emissions from municipal solid waste. In this study, we analysed the changes in the generation, composition and management of municipal solid waste in Beijing. The changes of greenhouse gas emissions from municipal solid waste management were thereafter calculated. The impacts of municipal solid waste management improvements on greenhouse gas emissions and the mitigation effects of treatment techniques of greenhouse gas were also analysed. Municipal solid waste generation in Beijing has increased, and food waste has constituted the most substantial component of municipal solid waste over the past decade. Since the first half of 1950s, greenhouse gas emission has increased from 6 CO2-eq Gg y(-1)to approximately 200 CO2-eq Gg y(-1)in the early 1990s and 2145 CO2-eq Gg y(-1)in 2013. Landfill gas flaring, landfill gas utilisation and energy recovery in incineration are three techniques of the after-emission treatments in municipal solid waste management. The scenario analysis showed that three techniques might reduce greenhouse gas emissions by 22.7%, 4.5% and 9.8%, respectively. In the future, if waste disposal can achieve a ratio of 4:3:3 by landfill, composting and incineration with the proposed after-emission treatments, as stipulated by the Beijing Municipal Waste Management Act, greenhouse gas emissions from municipal solid waste will decrease by 41%.