Seasonal characterisation of municipal solid waste from Astana city, Kazakhstan: Composition and thermal properties of combustible fraction

Global perspective of municipal solid waste and landfill leachate: generation, composition, eco-toxicity, and sustainable management strategies

Globally, more than 2 billion tonnes of municipal solid waste (MSW) are generated each year, with that amount anticipated to reach around 3.5 billion tonnes by 2050. On a worldwide scale, food and green waste contribute the major proportion of MSW, which accounts for 44% of global waste, followed by recycling waste (38%), which includes plastic, glass, cardboard, and paper, and 18% of other materials. Population growth, urbanization, and industrial expansion are the principal drivers of the ever-increasing production of MSW across the world. Among the different practices employed for the management of waste, landfill disposal has been the most popular and easiest method across the world. Waste management practices differ significantly depending on the income level. In high-income nations, only 2% of waste is dumped, whereas in low-income nations, approximately 93% of waste is burned or dumped. However, the unscientific disposal of waste in landfills causes the generation of gases, heat, and leachate and results in a variety of ecotoxicological problems, including global warming, water pollution, fire hazards, and health effects that are hazardous to both the environment and public health. Therefore, sustainable management of MSW and landfill leachate is critical, necessitating the use of more advanced techniques to lessen waste production and maximize recycling to assure environmental sustainability. The present review provides an updated overview of the global perspective of municipal waste generation, composition, landfill heat and leachate formation, and ecotoxicological effects, and also discusses integrated-waste management approaches for the sustainable management of municipal waste and landfill leachate.

Implementation of anaerobic digestion for valorizing the organic fraction of municipal solid waste in developing countries: Technical insights from a systematic review

Anaerobic digestion (AD) as a waste management strategy for the organic fraction of municipal waste (OFMSW) has received attention in developed countries for several decades, leading to the development of large-scale plants. In contrast, AD of OFMSW has only recently drawn attention in developing countries. This systematic review was carried out to investigate the implementation of AD to treat the OFMSW in developing countries, focusing on assessing pilot and full-scale AD plants reported in the last ten years. Studies that met the selection criteria were analyzed and data regarding operating parameters, feedstock characteristics, and biogas, digestate, and energy production were extracted. As outlined in this systematic review, AD plants located in developing countries are mostly one-stage mesophilic systems that treat OFMSW via mono-digestion, almost exclusively with the aim of producing electrical energy. Based on the analysis done throughout this systematic review, it was noted that there is a large difference in the maturity level of AD systems between developing and developed countries, mainly due to the economic capacity of developed countries to invest in sustainable waste management systems. However, the number of AD plants reported in scientific papers is significantly lower than the number of installed AD systems. Research articles regarding large-scale implementation of AD to treat OFMSW in developed countries were analyzed and compared with developing countries. This comparison identified practices used in plants in developed countries that could be utilized in the large-scale implementation and success of AD in developing countries. These practices include exploiting potential products with high market-values, forming partnerships with local industries to use industrial wastes as co-substrates, and exploring different biological and physical pretreatment technologies. Additionally, the analysis of capital and operational costs of AD plants showed that costs tend to be higher for developing countries due to their need to import of materials and equipment from developed countries. Technical, economical, and political challenges for the implementation of AD at a large-scale in developing countries are highlighted.

Exploration and prediction of wet season municipal solid waste for power generation in Ilorin metropolis, Nigeria

The wet season municipal solid waste (MSW) was characterized on Lasoju/Eyenkorin dumpsite for May to August 2020. The aggregate of waste generated was estimated to be 135,882 tons, while the aggregate characterized was estimated to be 80,700 tons. There are thirty-two samples of 240 L (bin of MSW) per sample considered in this investigation. There are twenty-one waste components categorized altogether, with packaging box having the highest proportion of 10.04%, followed by food residue of 9.64%, nylon 9.51%, and leather with the least fraction (0.75%) of the weight basis. Experimental investigations were performed on fourteen combustible fractions of the waste to determine the moisture content, elemental contents, and high heating value. The laboratory analysis reveals that the average carbon content available is 55%, 7% hydrogen, 1.35% nitrogen, 0.44% sulphur, and 30% oxygen; the low heating value of the waste was determined to be 23 MJ/kg. About 672 tons of MSW were investigated for energy production to give an energy and power potentials of 4.2 GWh and 53 MW discretely. The estimated electrical power potential for the wet season MSW is capable of meeting about 59% of the power demand for the Ilorin metropolis.

Source separation, transportation, pretreatment, and valorization of municipal solid waste: a critical review

Waste sorting is an effective means of enhancing resource or energy recovery from municipal solid waste (MSW). Waste sorting management system is not limited to source separation, but also involves at least three stages, i.e., collection and transportation (C&T), pretreatment, and resource utilization. This review focuses on the whole process of MSW management strategy based on the waste sorting perspective. Firstly, as the sources of MSW play an essential role in the means of subsequent valorization, the factors affecting the generation of MSW and its prediction methods are introduced. Secondly, a detailed comparison of approaches to source separation across countries is presented. Constructing a top-down management system and incentivizing or constraining residents' sorting behavior from the bottom up is believed to be a practical approach to promote source separation. Then, the current state of C&T techniques and its network optimization are reviewed, facilitated by artificial intelligence (AI) and the Internet of Things technologies. Furthermore, the advances in pretreatment strategies for enhanced sorting and resource recovery are introduced briefly. Finally, appropriate methods to valorize different MSW are proposed. It is worth noting that new technologies, such as AI, show high application potential in waste management. The sharing of (intermediate) products or energy of varying processing units will inject vitality into the waste management network and achieve sustainable development.

Seasonal characterization of municipal solid waste for selecting feasible waste treatment technology for Guwahati city, India

As quantities and composition of municipal solid waste (MSW) vary significantly with seasons, a seasonal characterization study is critical for developing an efficient MSW management system. MSW was characterized in three different seasons for selecting an appropriate waste treatment and management strategy for Guwahati city. Results of the study shows that the major components of the MSW were organics (42.2%) and plastic wastes (25.2%), which show high variations on a seasonal basis (22-49%). The chemical characterization of MSW revealed that on seasonal basis moisture content varies between 43.4% and 58.3%, pH between 5.5 and 6.5, volatile solid content from 32.9 to 58.9%, and the calorific value between 1203 and 3015 kcal/kg. Waste collected in the present study was a mixture of organics, recyclables, and inert material which is difficult and uneconomical for treatment in its present form. However, with proper waste segregation, bio-methanation, and composting could be sustainable waste treatment solutions due to the high moisture and volatile content of the MSW. Due to inadequate quantity, low calorific values, requirement of skilled supervision, and high capital investment, the thermochemical conversion of MSW may not be economically feasible for the present case.Implications: Present study is a novel attempt to analyze in-depth variation in the municipal solid waste (MSW) composition and properties in different seasons and how does it influence the selection and feasibility of the available waste treatment technologies. Search on Google scholar shows that only seven articles have been published till now which evaluated seasonal impact of MSW. Out to these published studies only one study have calculated energy potential of MSW on seasonal basis which is mainly restricted to incineration only. In-depth analysis of seasonal variation on anaerobic digestion, composting, refuse derived fuel (RDF), pyrolysis, and gasification is yet to determine. Furthermore, to best of our knowledge so far in India there was no such in-depth study has been published related to seasonal variation in MSW on large scale (city level). Present study provides in-depth valuable information regarding degree of variation in MSW composition and how does it affect resource recovery out of waste, which was not studied before in-depth before. Outcomes of the present study will definitely assist engineers and policymaker involved MSW management and planning for large urban areas to fulfil their sustainability goals.

Market waste composition analysis and resource recovery potential in Kumasi, Ghana

Municipal solid waste constitutes significant quantities of waste generated in markets. Markets produce substantial quantities of fruit and vegetable waste, a source of nuisance in landfills. In Ghana, market waste (MW) appears to be unexplored and has limited data available. The need for MW valorization in the face of a circular economy requires reliable knowledge of MW properties. The study determined the waste compositions of selected major markets from two different classes of settlement in Kumasi and the seasonal effect on the compositions. The chemical properties of organics were determined via proximate and ultimate analyses and the theoretical biomethane potential, with the Buswell equation. From the results, MW composition in the wet season is 59.6% organic, 11.4% plastics, 8.3% paper, 5.3% textiles, 4.7% inert, 4.1% miscellaneous, 2.1% metal, 1.8% glass and 2.8% leather. The dry season values are 45.8% organic, 14.6% plastics, 12.7% paper, 7.3% textiles, 6.4% inert, 4.3% miscellaneous, 2.3% metal, 2.6% glass and 3.9% leather. An ANOVA indicates significant differences between the two seasons and some waste components; organics, plastics, paper and cardboard, leather, and inert. The high calorific values recorded ranged from 14.8 MJ kg^-1 to 16.6 MJ kg^-1. The biogas potential and biomethane content ranged from 775.3 l/kgVS to 828.9 L/kgVS and 50% to 57% respectively.Implications: Market waste (MW) in Ghana appears to be an unchartered area and there is limited data on market generation and composition. The need for MW valorization requires reliable knowledge on MW properties. This study explores MW characteristics of six major market from two different classes of settlements in a developing country. Study findings suggest that the quantities of market organics are higher than household waste. Again, MW composition can be influenced by season and geographical location. Furthermore, the study establishes the potential of MW in considerable quantities of biogas and methane generation, in comparison with household waste.

Designing the biomethane production chain from urban wastes at the regional level: An application to the Rome Metropolitan Area

This paper proposes a methodology to design the biomethane production chain from MSW at the regional level and to assess the environmental and economic performance of the chain. In the design phase, the following parameters are considered: number and production capacity of biomethane plants, localization of plants, waste flows among municipalities and plants. The model is adopted to design the biomethane chain in the Rome Metropolitan Area (Italy). Several structures of production chain are designed and their performances are assessed. The economic factors mostly able to affect the performance of the chain are waste disposal tariff, biomethane selling price, and the economic incentive provided to biomethane producers. Their impacts are discussed through sensitivity analyses. Results show that the structure maximizing the economic performance has the worst environmental performance and vice versa. Hence, a new structure of the economic incentive is proposed, aimed at re-aligning economic and environmental performance.

Characterization and projection of dry season municipal solid waste for energy production in Ilorin metropolis, Nigeria

This research investigates the quantity of municipal solid waste produced during the dry season, and its characterization at Eyenkorin dumpsite of Ilorin metropolis, along the Lagos-Ilorin express way. The physicochemical and thermal compositions of the combustible fractions of municipal solid waste were analysed, to ascertain the available calorific value. In this research, the quantity (tonnes) of waste generated, the rate of generation (kg per capita per day), its sustainability and the likely energy and power potentials in the dry season, were essentially predicted. The population responsible for municipal solid waste generation during this study was 1,120,834 people. During the characterization study from November 2018 to February 2019, it was established that 203,831 tonnes of municipal solid waste was produced during the four months of the dry season, at the rate of 1.12 kg per capita per day. It was found that 280 tonnes/day of municipal solid waste with low heating value of 19 MJ kg^-1, would generate 1478 MWh of heat energy and 18 MW of electrical energy potentials discretely, and grid of 13 kW.

Application of artificial neural networks for predicting the physical composition of municipal solid waste: An assessment of the impact of seasonal variation

Sustainable planning of waste management is contingent on reliable data on waste characteristics and their variation across the seasons owing to the consequential environmental impact of such variation. Traditional waste characterization techniques in most developing countries are time-consuming and expensive; hence the need to address the issue from a modelling approach arises. In modelling the complexity within the system, a paradigm shift from the classical models to the intelligent models has been observed. The application of artificial intelligence models in waste management is gaining traction; however its application in predicting the physical composition of waste is still lacking. This study aims at investigating the optimal combinations of network architecture, training algorithm and activation functions that accurately predict the fraction of physical waste streams from meteorological parameters using artificial neural networks. The city of Johannesburg was used as a case study. Maximum temperature, minimum temperature, wind speed and humidity were used as input variables to predict the percentage composition of organic, paper, plastics and textile waste streams. Several sub-models were stimulated with combination of nine training algorithms and four activation functions in each single hidden layer topology with a range of 1-15 neurons. Performance metrics used to evaluate the accuracy of the system are, root mean square error, mean absolute deviation, mean absolute percentage error and correlation coefficient (R). Optimal architectures in the order of input layer-number of neurons in the hidden layer-output layer for predicting organic, paper, plastics and textile waste were 4-10-1, 4-14-1, 4-5-1 and 4-8-1 with R-values of 0.916, 0.862, 0.834 and 0.826, respectively at the testing phase. The result of the study verifies that waste composition prediction can be done in a single hidden-layer satisfactorily.

Detailed municipal solid waste composition analysis for Nur-Sultan City, Kazakhstan with implications for sustainable waste management in Central Asia

A detailed characterization of municipal solid waste (MSW) beyond a standard compositional analysis may offer insights useful for improving waste management systems. The present paper contributes to the scarce literature in the field by presenting new data from a rapidly developing Central Asian city, the capital of Kazakhstan, Nur-Sultan. Three sampling campaigns (each 1 week long) have been conducted at the city landfill over a 1-year period (2018-2019), and a detailed characterization for selected waste components and sub-components has been performed. The major fractions of MSW were organics (46.3%), plastics (15.2%), paper (12.8%), and diapers (5.9%). The detailed composition analysis showed high LDPE (low-density polyethylene) content (5.5%) mostly comprised of plastic bags (4.5%), transparent glass (3.2%), pharmaceuticals (0.4%), and fine (i.e., < 12 mm) organic fraction content (29%). The MSW generation rate of Nur-Sultan was estimated as 1.47 kg capita^-1 day^-1 based on the field collection as well as literature data. Among sustainable waste management recommendations addressed for Nur-Sultan and applicable to other cities in Central Asia, composting is recommended due to high organics fraction in MSW and its great potential to reduce the landfilled waste volume and to help valorizing the waste.

Thermogravimetric Study of Refuse Derived Fuel Produced from Municipal Solid Waste of Kazakhstan

Efficient waste management, including proper utilization of municipal solid waste (MSW), is imperative for a sustainable future. Among several management options, pyrolysis and combustion of MSW has regained interest because of improved combustion techniques. This work aims to investigate the thermal conversion and combustion characteristics of refuse derived solid fuel (RDF) samples and its individual compounds collected from Nur-Sultan’s MSW landfills. The waste-derived solid RDF samples originally consist of textile, mixed paper, and mixed plastic. In particular, the samples, including RDF and its three constituent components, were analyzed in the temperature range of 25 to 900 °C, at three different heating rates, by thermogravimetric method. The gross calorific value for RDF derived from Nur-Sultan’s MSW was determined to be 23.4 MJ/kg. The weight loss rates of the samples, differential thermogravimetry (DTG), and kinetic analysis were compared between individual RDF components and for the mixed RDF. Combustion kinetics models were calculated using Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman methods. The results revealed that first decomposition of RDF samples was observed at the range of 180–370 °C. Moreover, the activation energy for conversion of RDF was observed to be the highest among the constituent components and gradually decreased from 370 to 140 kJ/kmol.

Survey on Household Solid Waste Sorting at Source in Developing Economies: A Case Study of Nur-Sultan City in Kazakhstan

The exponential population growth in urban areas makes existing solid waste management policies and strategies challenging. The situation becomes more strenuous in fast-growing cities where increasing waste production can hardly be met by the capacity of existing facilities. Practices like waste prevention, recycling, reuse, and recovery are fundamental elements needed for the reduction of solid waste disposed in landfills, especially in fast-growing cities where more sustainable management practices need to be adopted. This study investigated the behavioral attitudes of citizens of the capital of Kazakhstan, Nur-Sultan (former Astana), towards household solid waste disposal and separation at the source. The survey was conducted through stratified random sampling during April and July of 2018 with the participation of 3281 respondents. It is the first attempt, to our knowledge, of assessing recycling trends in Kazakhstan from the household perspective. The results showed that 24% of respondents were already sorting household solid waste despite the absence of a separation system at the source. The study further demonstrated that separation at source could be effective if the local authorities were to introduce sound public awareness campaigns and install recycling bins in close proximity to residential buildings.