Solid Waste Management: Comparison
Please note this is a comparison between Version 2 by Ahsen Maqsoom and Version 4 by Jason Zhu.

Disposal of municipal solid waste (MSW) is one of the significant global issues that is more evident in developing nations. One of the key methods for disposing of the MSW is locating, assessing, and planning for landfill sites.  Due to rapidly expanding global urbanization, associated lack of resources, and inadequate urban waste management, MSW issues and management concerns are on the rise. Over a third of total municipal waste out of two billion tons generated remains uncollected worldwide. MSW is collected and disposed of at certain locations or burnt down in most developing nations. Landfill sites for solid waste must be inspected in terms of all requirements to reduce economic and environmental expenses.

  • landfilling
  • Solid waste
  • municipal solid waste
  • remote sensing
  • geographical information systems

1. Introduction and Background

With the growth in global populations (particularly in cities), concerns regarding urban health are rising [1][2][1,2]. Various waste reduction techniques such as lean, total quality management, and six sigma have been presented to reduce and minimize waste [3][4][3,4]. The solid waste in the form of trash, garbage, and refuse daily dumped by urban and rural populations is known as municipal solid waste (MSW). Every year, around 1.3 billion tons of MSW are generated worldwide, which is expected to increase to 2.2 billion tons by 2025, with over a third of this MSW left uncollected [5]. The United States, Canada, Australia, Germany, South Africa, France, and the United Kingdom are among the highest per capita MSW-generating countries [5]. Expanding global urbanization, inadequate urban waste management, and a lack of resources around the globe contribute to the rise in MSW [6][7][6,7]. Every day, 0.74 kg of rubbish is generated per person in the municipality of Phnom Penh, Cambodia alone [8]. The World Bank claims that by 2050 the MSW generation will reach 3.4 billion tons [9]. Around 70% of MSW is dumped in landfills, while 19% of the waste is recycled, and 11% is used for energy generation. Among the world’s current population, i.e., 7.6 billion people [10], around 3.5 billion have no access to basic garbage collection services [11].

2. Solid Waste Management

Solid waste management aims at disposing of the garbage in the most environment-friendly manner possible. This is achieved through the assistance of the local people directly impacted by a region’s solid waste program [12]. Solid waste is collected from houses, workplaces, small companies, and commercial enterprises. In the EU, this is considered a special waste stream. Such waste combined with the waste created during construction, renovation, and demolition is referred to as the MSW. Kitchen rubbish, paper and cardboard, yard waste, metal, plastic and rubber, electronic waste, glass, bricks, concrete, inert materials, and miscellaneous garbage are all examples of MSW. MSW is classified in various ways by global municipalities. It contains organic and inorganic components and biodegradable and non-biodegradable components. To minimize the generation of solid waste, various strategies are employed globally. Preventing, reusing, recovering, recycling, and disposing of waste are the most popular approaches to reducing solid waste [13]. The regular storage of solid waste is another strategy utilized to avert potential environmental hazards [14][15][14,15].
MSW management techniques differ by municipality, city, state, and nation based on the waste composition. Poor MSW management increases greenhouse gas emissions and has serious consequences for human health and environmental safety [16][17][18][16,17,18]. Different treatment and recycling processes are used globally for managing MSW. Classified recycling, incineration, landfilling, composting, and anaerobic digestion are some examples of MSW treatment and recycling procedures [19][20][21][19,20,21]. Most developing nations burn the MSW or gather and dump it at specific locations in the form of landfill sites [22]. For example, in Iran, the bulk of MSW is buried in open pits. Such open dumping poses long-term environmental and human health risks [6][23][6,23].
Landfill sites are commonly used for burying non-recyclable garbage across the world. These landfills must be inspected and compliance assured before being utilized as a solid waste dumping site. In addition, these landfills must meet regulatory, geographical, hydrological, and topographical requirements to manage and reduce environmental, economic, hygienic, and social concerns [1][24][25][1,24,25]. Nonetheless, rubbish is dumped into pits in several underdeveloped countries rather than buried in the ground. Despite the rapid development of alternate disposal techniques, the landfill in the forms of open dumping and sanitary landfill remains the most preferred disposal option in such countries. This is due to the lesser costs and technical requirements for such dumping in developing economies.
According to the United Nations Environment Programme (UNEP), open dumping and sanitary landfills account for 51% and 31% of waste disposal in Asia. Incineration and recycling account for just 5% and 8% of total waste. In Africa, open dumping and sanitary landfills account for 47% and 29% of total waste [26]. In North America, sanitary landfills account for 91% of garbage disposal [27]. It illustrates that most nations utilize landfills to dispose of their MSW, since it is less expensive than alternative options [28]. Landfills are used as approved locations for MSW dumping, with garbage processing and recyclable material sorting regulated before dumping. Landfilling is a frequently utilized procedure in municipalities worldwide for safe processing and disposing of solid waste [29][30][29,30]. Landfilling has long been a popular waste disposal practice in many developing countries [31]. This is because in such weaker economies, cost is the key factor and there is generally a lack of environmental considerations in developing countries. However, this must change in the era of striving for global sustainability and environmental protection. Accordingly, incentives must be provided to relevant stakeholders to conduct resource recovery operations and reduce the environmental burdens of such landfills.
On the other hand, incineration requires significant infrastructure investments and can create extremely high temperatures and adversely affect the climate and environment. Similarly, resource recovery processes such as pyrolysis, liquefaction, gasification, anaerobic digestion, and composting have extensive staffing, equipment, and cost requirements. Therefore, landfilling is preferred due to the cost-effectiveness and labor-intensive procedures in developing countries. Furthermore, the combined landfill may create profits by generating electricity from landfill gas and leachate. Landfilling is a common practice in developing countries; however, as previously discussed, this practice should not be encouraged, and more environment-friendly and sustainable approaches should be adopted. These include using greener materials, encouraging and incentivizing recycling, and other green initiatives aligned with the United Nations’ sustainable development goals. Climate change cannot be tackled in the absence of such holistic measures and considerations for the environment. This also goes against the circular economy concept, which is at the forefront of global greening initiatives.

3. Landfilling 

Overall, landfilling is still a prevalent MSW technique but cannot be termed as the best option unless actions are taken to transform the dump into something useful. For example, these landfills can be transformed from “garbage dumps” to “energy powerhouses” by installing integrated technology to generate recycled materials and renewable energy. According to Nabavi-Pelesaraei et al. [32], landfills and treatment facilities for domestic rubbish, hazardous chemicals, radioactive wastes, construction, demolition, and renovation wastes are all located in distinct areas that can serve as energy generation points. In addition, landfill mining reclaims valuable recyclables and combustible landfill gases from landfill sites to help free up landfill areas and promote sustainability [33][34][33,34].
Landfills can be divided into different classes based on the usage. Class 1 landfills are used for soil disposal. Class 2 landfills are used for mineral disposal and construction and demolition waste. Class 3 landfills are used for the disposal of MSW. Class 4 landfills are used for the disposal of commercial and industrial trash. Class 5 landfills are used for disposing of hazardous waste. Finally, Class 6 landfills are used for dangerous underground waste disposal [35]. In terms of types of landfills, the most common ones include secure landfills, monocle landfills, reusable landfills, and bioreactor landfills [36]. To stall harmful environmental consequences, the wastes are enclosed in secure landfills. The waste that cannot be treated by incineration or composting is dumped into monocle landfills. Reusable landfills enable rubbish to settle for longer periods before digging for recovery of metals, plastics, and fertilizers.
In terms of control, there are three types of landfills: semi-controlled, open, and sanitary landfills [37]. MSW dumped in an open environment is called an open dump landfill. Most developing countries have open dumps, where MSW is randomly discharged into low-lying open regions. In such poorly managed landfills, scavengers, other birds, mosquitoes, bugs, rodents, and deadly germs find a home, promoting health concerns.
Researchers have investigated various methods for choosing dumping or landfill locations globally. Scholars have used mathematical models to choose dump locations [38]. Based on the analytical hierarchy process (AHP), Lokhande et al. [38] used GIS to locate a trash disposal site. The same has been used by other studies [39][40][41][42][43][39,40,41,42,43]. For example, Spigolon et al. [40] determined landfill siting based on optimization, multiple decision analysis, and GIS. Şener et al. [41] selected solid waste disposal sites with GIS and AHP methodology using a case study in Senirkent–Uluborlu (Isparta) Basin, Turkey. Similarly, Sumathi et al. [42] used a GIS-based approach for optimized siting of municipal solid waste landfills.
A researchtudy was conducted in Iran using the GIS and multi-criteria decision-making methods (MCDM) [44]. GIS-based multi-criteria decision analysis (MCDA) and evaluation were used for landfill site selection in Ethiopia [45]. The researcheuthors used AHP and weighted linear combination models. In the city of Rudbar in Iran, with a harsh morphological and sensitive environment, fuzzy logic spatial modeling has been used for landfill site selection [46]. Wang et al. [47] selected waste disposal sites and highlighted the associated environmental risks. In Javanrud, Iran, trash was disposed of in a landfill using GIS and MCDA [23]. In Syria, GIS-based normalized difference vegetation index (NDVI) and normalized difference snow index (NDSI) techniques have been used to dispose of war trash [48]. GIS and RS have also been used for managing rising environmental problems of waste disposal [49]. In Pakistan, different combinations of satellite based bio-thermal indicators were used to monitor open dumps [50]. However, a study for identifying landfill sites for MSW has not been reported to date for Pakistan. This presents a gap targeted in the curresearchnt study. For this purpose, integrated RS and GIS have been used in this study.
According to the literature, most researchers relied on judgments regarding numerous factors involved in their search for the best MSW disposal locations. These opinions were combined with GIS data to locate the landfill sites [1]. The GIS and RS data were used to create a rating system for identifying landfills that ranged from the least to the most acceptable. Similarly, rather than building new facilities, the researcheuthors suggested researching growing nations using a ranking system based on Thiessen polygons to locate appropriate locations meant for landfill development. CThe current studiesy builds upon these works and aims to offer a forum for decision-makers to analyze feasible landfill expansion regions in Pakistan. This is evident in developed countries like Canada, where GIS and RS data are commonly utilized for making informed landfill decisions [51]. Accordingly, the site of a landfill expansion is selected using factors such as proximity to garbage sources to reap financial advantages from lower waste transportation costs and less severe environmental and health impacts [47].
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