Waste to Energy in Developing Countries—A Rapid Review: Opportunities, Challenges, and Policies in Selected Countries of Sub-Saharan Africa and South Asia towards Sustainability

Abstract

Daily per capita waste generation will increase by 40% and 19%, for developing and developed countries by 2050, respectively. The World Bank estimates that total waste generation is going to triple in Sub-Saharan Africa (SSA) and double in South Asia (SA) by 2050. This article conducts a rapid review and aims to demonstrate the current waste management scenario and the potential of waste to energy generation in the developing world, focusing on SSA and SA. Although many review articles related to waste to energy (WtE) in developing countries are available in the literature, a rapid review particularly focusing on countries in SSA and SA is rarely seen. An analysis of different WtE generation technologies, and current waste management practices in developing countries in SSA and SA are also presented. The analysis shows that about three-fourths of waste is openly dumped in developing countries of SSA and SA. In terms of waste composition, on average, about 48.70% and 51.16% of waste generated in developing economies of SSA and SA are organic. Opportunities to convert this waste into energy for developing countries are highlighted, with a case study of Bangladesh, a country in SA. Major challenges regarding the waste to energy (WtE) projects in the developing world are found to be the composition of waste, absence of waste separation scheme at source, ineffective waste collection method, lack of suitable WtE generation technology in place, lack of financial support and policies related to a WtE project, and absence of coordination between different governmental institutions.

1. Introduction

The global waste crisis is an effect of untreated, unsafe disposal and inefficient waste collection. Population growth and urbanization are the two most crucial factors behind waste generation. Global average waste generation varies between 0.11 and 4.54 kg/person/d [1]. Waste management operation is both complex and costly. On average, waste management requires about 19, 11, and 4% of total annual municipal budgets for low-, middle-, and high-income countries [1].

Waste generation and management are directly related to the UN’s sustainable development goals (https://sdgs.un.org/goals (accessed on 10 March 2021)), notably, goals 12 and 13. For instance, waste is responsible for air pollution and has severe health impacts, if it is not treated through proper technology. In the developing world, most of it is either dumped in an open place or burned. Consequently, both of these methods of waste treatment pollute the air and raise health issues. In addition, methane and CO₂ emissions from open dumpsites are responsible for adverse climate change.

One of the sub-goals of SDG-12 is, by 2030, substantially reduce waste generation through prevention, reduction, recycling, and reuse. This could be connected to SDG-7: Ensure access to affordable, reliable, sustainable, and modern energy for all. That is, by 2030, increase substantially the share of renewable energy in the global energy mix. Waste could be one of the potential renewable sources of energy if appropriately treated. Nowadays, waste to energy (WtE) is one of the promising technologies that has been well employed in the developed world. However, a very limited application can be seen in developing countries.

Waste can be treated in many different ways, such as controlled landfills and mass burning. Waste to energy conversion is one of the latest forms of waste treatment, offering a number of benefits [2]. It can generate electricity using different technologies, such as incineration, anaerobic digestion [3]. WtE generation helps to reduce greenhouse gas emissions [4]. New WtE plants create new employment opportunities [5]. It offers a more efficient waste management system [6] and contributes to sustainable development [7]. However, these options are mostly utilized in the developed world, such as in Italy, Germany, Finland, France, and Japan [8,9]. The most polluted cities in the world are mainly in developing countries, where waste is mostly untreated and results in air pollution [10,11]. How and what portions of wastes are treated in these developing countries and how it could be treated in the future towards sustainable development are rarely addressed in the literature, and this study attempts to close this gap.

Greenhouse gas (GHG) emissions from different sectors, including electricity generation, is a vital factor that hampers sustainable development. Even renewable energy, such as hydroelectricity, is not free from emissions [12]. It is well known that the electricity generation from fossil fuels is a major contributor to global GHG emissions and are higher than emissions from renewable sources. For example, the carbon intensities of gas- and oil-fired power plants in Bangladesh with efficiencies of about 22% and 16% were found to be 930 and 1752 gCO₂-e/kWh [13]. Only about 180 gCO₂-e/kWh carbon intensity was found for the electricity generation system of New Zealand [14], as its electricity system is dominated by renewable generation, including hydro (57%), geothermal (17%), and wind (6%) [15]. Due to continuous urbanization, waste has become a challenge not only for developed countries [16], but for the developing economies that need to transform waste into opportunities, which in turn will help achieve future sustainable development. Untreated wastes are the major sources of GHG emissions. WtE could be a potential technology to reduce these GHG emissions [17]. A study in Korea found that ‘in 2012, GHG reduction by waste-to-energy was 16,061 tCO_2eq /yr; it is predicted to be 33,477 tCO_2eq /yr in 2021′ [4]. WtE technologies are not free from emissions [18]. Emission ranges vary from one technology to another: anaerobic digestion was found to be more environmentally friendly than incineration, gasification, and pyrolysis [19].

There are three different types of WtE conversion processes: thermochemical, biochemical, and chemical. All these WtE generation processes are summarized in

Table 1. Different WtE generation technologies (Data Source: [9,20,21]).

Conversion Process	Technologies	Process	Feedstock	Residues	Outputs
Thermo-chemical	Incineration	Mass burn at temperature > 1000 °C	Mixed waste, refuse-derived fuels (RDF)	Bottom ash, fly ash, metals, air pollutants	Heat and electricity (energy)
	Gasification	Conventional temperature 750 °C; for plasma arc 4000–12,000 °C	Mixed waste, RDF	Bottom ash, air pollutants	Hydrogen, methane, syngas → electricity (energy)
	Pyrolysis	At temperature between 300–800 °C with high pressure and in the absence of oxygen	Sorted waste (e.g., plastics), organic waste	Air pollutants	Char, pyrolysis oil, gases, aerosols, syngas → electricity (energy)
Bio-chemical	Fermentation	In the absence of oxygen: Dark fermentation- treated with bacteria in the absence of light; photo fermentation- treated with bacteria in the presence of light	Organic waste with high sugar content	Liquid residues, wastewater, digestate	Ethanol, hydrogen, biodiesel → energy
	Anaerobic Digestion	Treated by micro-organisms in the absence of oxygen	Organic waste, green waste	Wastewater, liquid residues, digestate, non-compostable materials (e.g., metal, plastics)	Methane → electricity (energy)
	Landfill with gas capture	Natural decomposition of waste	Organic waste, green waste	Compost	Methane → electricity (energy)
	Microbial fuel cell	The catalytic reaction of micro-organisms with bacteria	Organic waste	CO2, water	Electricity (energy)
Chemical	Esterification	A chemical reaction between an acid and alcohol in the presence of an acid catalyst to create ester	Waste oil (e.g., waste coconut oil)	Water	Ethanol, biodiesel → energy

Note: (→) indicates the final output.

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The objective of this study is to conduct a rapid review and identify opportunities and challenges related to WtE generation in developing countries, particularly focusing on selected countries in Sub-Saharan Africa (SSA) and South Asia (SA) by investigating the type of waste generated, its contents, and treatment procedures. A case study of Bangladesh is presented to obtain a detailed insight into a WtE generation project in a developing country in SA. Generalized policy implications are indicated for these developing countries.

The rest of the article is organized as follows: Section 2 describes the method and materials used for this study. Section 3 reviews the literature related to WtE in developing economies. Section 4 presents the analysis and results. Section 5 discusses the opportunities and challenges associated with WtE generation for developing countries. This section explains the steps that need to be followed in developing WtE policymaking for developing economies. This section also indicates related policy implications. The final section concludes the article.

2. Materials and Methods

A rapid review method was employed for this study along with a quantitative data analysis. “In rapid reviews, a wide variety of methods can be used to speed up the process of literature search and evaluation, while at the same time maintaining the principles of methodological quality and transparent reporting” [22]. In an earlier study, Grant and Booth (2009) defined it as an “assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research” [23]. Therefore, the form of evidence synthesis method by which a decision can be made within a short time frame compared to standard systematic reviews is known as a rapid review method. Due to its useful characteristics, many recent studies in various research fields used this review method in the literature, see for example, [24,25,26]. This review is best-suited for-

• An emerging research topic
• An update of previously conducted reviews
• An analysis of critical topics within a short time frame
• An assessment of ‘what is already known’ regarding a policy or practice through some systematic review methods

The characteristics of the rapid review method are illustrated in Figure 1. Although the rapid review method was beneficial for this study, it also has some limitations: reducing the review time may introduce biases, the search is not comprehensive, and interpretation of the findings might be limited. For instance, Grant and Booth (2009) reported that “limiting the time taken to search may result in publication bias, limiting appraisal or quality assessment may place a disproportionate emphasis on poorer quality research, while a lack of attention to synthesis may overlook inconsistencies or contradictions” [23]. One of the ways to eliminate these biases is to document the methodology properly and explicitly declare its limitations.

Secondary data were used for this analysis. Secondary data could be collected from an authentic source, the advantage being that these data have already been tested, filtered, and are ready to use. For this analysis, the World Bank’s ‘What a Waste Global Database’ was used [33]. This database, which was released in September 2018 and is publicly accessible, covers more than 330 cities’ waste generation, collection, disposal, and composition statistics.

Secondary data were used for this analysis for the following reasons. It is a reliable source of data covering the world’s waste statistics. It is easier and faster to access than primary data, and this type of secondary research provides information to countries about the effectiveness of further primary research in this area. In evaluating the selected dataset, the standard criteria/questions were followed/addressed [34]. The purpose of the primary study (i.e., data collection) was to aggregate data on solid waste management under the global project ‘What a Waste’. The data reported are predominantly between 2011 and 2017. For details about the dataset used, see ‘a note on data’ in [35].

According to World Bank, estimates of 2015 gross national income (GNI) per capita, 27 lower-income countries (GNI = USD 1025 or less) were selected in SSA. Twelve of these countries’ waste composition data were not available and thus excluded, leaving 15 countries selected. The eight developing countries were selected from the SA region. The main reason for selecting these countries for this analysis is that total waste generation by 2050 is going to increase about three and two times compared to the figures for 2016 in SSA and SA, due to economic growth [35]. A comparative short- and long-term projection is illustrated in Figure 2, showing that the projected waste generation will be dominated by these two regions in both the short- and long-term. The short-term growth would be 54.60% and 39.52% for the SSA and SA regions, whereas the long-term growth would be 196% and 98% for SSA and SA. For detailed insight, a waste to energy generation project in Jashore, Bangladesh was considered as a case study. For this initial pilot project, the data were collected predominantly from a recent waste to energy feasibility study [36], a newspaper report [37], and a TV report available on YouTube (https://www.youtube.com/watch?v=zxtn3gy3-1U (accessed on 25 June 2020)).

Following the rapid review method, only the sciencedirect.com database was used for the literature search, and the timeframe was selected to be from January 2016 to the end of February 2022. Although the articles published between 2016 and February 2022 were considered for the literature survey, a few other earlier publications were also considered, as they are very closely related to the discussed topic. Published research and review articles were only considered for this study. Initially, the keyword ‘waste to energy’ was used to search the related literature. It resulted in thousands of articles. Thus, more specific keywords were used for the search such as, ‘energy recovery in developing countries’, ‘waste to bioenergy in developing countries’, ‘waste to energy in developing countries’ and ‘waste to energy in developing economies’. The words ‘developing countries/economies’ were kept in all searches. Primary screening resulted in 171 articles from many different journals. Further screening considering the developing nations only resulted in 67 articles. The search process is illustrated in Figure 3.

3. Literature Review

The average waste generation rates for different small island developing states in the Caribbean, Pacific, Atlantic, Indian Ocean, Mediterranean, and South China were about 1.29 kg/capita/d, whereas, for the OECD countries, the rate was found to be 1.35 kg/capita/d [38]. Waste compositions were dominated by organics (44%) and recyclables (43%) for the developing states and OECD countries, respectively [38]. A recent study found that mass-burn incineration is the best option, followed by ‘hybrid mechanical-biological treated anaerobic digestion and refuse-derived fuel incineration’ in the Pacific small island developing states (PSIDS) [39]. Although their finding indicates that incineration is the most suitable option in these countries, the waste composition was dominated by organic components, which are more suitable for anaerobic digestion [40]. This contrasts with the situation in India, where biodegradable waste is about 50% of the total generated waste, and AD was found to be most suitable compared to incineration, gasification, and landfill with gas recovery [41].

An investigation involving a system approach was conducted for developing countries [42]. This review revealed that complexity exists in the solid waste management systems in the developing world due to ‘urbanization, inequality, and economic growth; cultural and socio-economic aspects; policy, governance, and institutional issues; and international influences’ [42]. For example, there is a good bioenergy potential from inedible agri-food loss and waste in Nigeria (which is about 1,816.8 ± 117.3 PJ, sufficient to meet 2030′s bioenergy national targets) [43], but Nigerians show poor attitudes and unfavorable traditions towards waste management [44]. Similarly, in Indonesia, about 49,810 MW renewable energy could be derived from plants and waste (i.e., biomass) [45].

There is limited use of WtE plants, in particular, thermal plants in some developing countries, such as China [17], India [46], and Thailand [47], who do not follow the waste management hierarchy of reduction, reuse, and recycling. It was also found that a combination of conventional and unconventional technologies is suitable for WtE generation in China to achieve a circular economy [48]. The WtE uptake is found to be unsuccessful in developing countries, for example, in India and Nigeria for a number of reasons, such as ‘poor source segregation’ [43,46]. Many other challenges, such as proper policymaking, need to be faced for successful WtE plants in developing countries [49]. Some well-identified challenges are lack of (i) regulation and technical standard, (ii) a suitable business model, (iii) technical localization and development, (iv) fly ash treatment and management, and (v) skilled labor [50]. In a recent review, Goli et al. (2021) found that “the higher capital investments and operation costs, lack of viable flue gas treatment techniques for furans/dioxins, availability of a conventional source of energy at cheaper costs, and demand for constituents of combustible fractions from infrastructure development for manufacturing of construction materials make these technologies unsuitable for reaching sustainable development goals in developing countries” [51]. ‘Lack of knowledge and experience under specific local conditions’ is another crucial barrier in implementing WtE plants in developing economies [52]. However, a recent study found that WtE has great potential in the Greater Bay Area in China using two waste treatment methods, namely landfills with the gas collection and incineration [53]. The authors estimated that about 31,346 and 77,748 GWh of electricity could be produced from the waste by 2030 and 2060, respectively.

Although organic components dominate developing countries’ wastes, the selection of WtE technology varies from one city to another. For instance, out of the total waste, the organic components were found to be 38.6%, 70.8%, and 67% in Delhi (India), Jakarta (Indonesia), and Karachi (Pakistan), respectively [54]. The authors found that new hybrid technology, favorable feed-in tariffs, and waste collection fees could underpin WtE plants in Delhi and Karachi. However, due to higher operational costs, this is challenging in Jakarta. A techno-economic analysis revealed that a hybrid system containing anaerobic digestion and gasification technologies are suitable for WtE generation in South Africa [55]. In Brazil, a low-cost product-service-system solution was proposed for the treatment of the organic waste and found that it is “potentially viable to be implemented in the Brazilian municipalities with lower population density, larger territorial area and per capita (GDP) equal to or higher than that of Porto Amazonas” [56]. In terms of economic assessment, Agaton et al. (2020) found that incineration is one of the most profitable WtE plants in the Philippines, followed by gasification and pyrolysis [57]. Another recent study in Brazil employed the ‘process flow diagram’ and ‘waste aware benchmark indicators’ and found that clear laws, regular public campaigns, and fee methodology would be helpful for urban household solid waste management [58].

About 20% to 50% of municipalities’ budgets in developing countries is spent managing and disposing of wastes. Waste management in most of these countries is still at a premature stage [59]. A new hybrid approach combining the binomial tree analysis and decoupled net present value (DNPV) was proposed in [60]. The proposed method was applied to Iran and the authors claimed that the approach is one of the robust methods that is able to assess the WtE project risks through sound practices for developing countries. Many other studies in the literature considered WtE production in developing countries, such as lignocellulosic biomass to second-generation ethanol [61], and a list of these studies is shown in

Table 2. Waste to energy production in different developing countries.

Developing Countries	Waste Source	Product (Technology Used)	References
Brazil	Defective coffee beans; Rice husk, Orange pear peel, Ponkan mandarin peel, Tahiti lemon peel; Coffee waste and pinewood	Hydrochar (Hydrothermal carbonization); Briquettes (Briquetting);	[62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91]
Colombia	Rice husk, Sugar cane bagasse, Coffee husk; Primary sludge Coal boiler ashes Wood waste of pulp/paper mill	Pellets (Pelletizing)
Turkey	Rose-oil processing waste, Pine bark, Coal powder	Pellets (Pelletizing)
Iran	Bagasse	Pellets (Pelletizing)
Egypt	Olive mill waste	Methane (Anaerobic digestion)
Ghana	Sewage sludge (SS), Faecal sludge (FS)	Biochar (Pyrolysis)
Uganda	Coffee husks, Rice husks	Briquettes (Pyrolysis and Compression),
Burkina Faso	Cashew press cakes	Briquettes (Slow pyrolysis and Briquetting)
Zimbabwe	Municipal solid waste	Electrical energy (Thermochemical)
Thailand	“Madan” wood + coconut shell	Briquettes (Charcoal kiln and Briquetting)
India	Pre-treated yard waste; Macrophyte; Yard waste, Food waste, Landfill leachate	Hydrochar (Microwave pre-treatment, Anaerobic digestion, Hydrothermal carbonization); Pelletized hydrochar (Hydrothermal carbonization, Hydraulic hand pellets press)
Bangladesh	Banana stalk, Wild date palm	Hydrochar (Hydrothermal carbonization); Bioethanol (Batch fermentation)
Malaysia	Oil palm trunk, Oil palm solid waste, Spent coffee ground, Palm kernel shell	Bio-coal (Pyrolysis), Torrefied solid (Torrefaction), Biochar (Slow pyrolysis), Biochar (Microwave vacuum pyrolysis)
Indonesia	Cashew nutshell waste	Briquettes (Pyrolysis, Briquetting)
China	Sewage sludge and phenolic wastewater, Cornstalk, Food waste, Sweet potato waste	Hydrochar (Hydrothermal, Microwave-assisted hydrothermal carbonization, Hydrothermal carbonization)

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It is evident from the literature that most of the previous studies focused on the waste to energy generation option as a potential waste management scheme in the developing world other than the countries in Sub-Saharan Africa and South Asia. Although many review articles related to WtE in developing countries are available in the literature, such as [92], a review particularly focusing on countries in Sub-Saharan Africa and South Asia is rarely seen. Closer to the present study, Abdallah et al. (2019) investigated the WtE potential in selected developing countries in the Middle East and North Africa (MENA) region, in which the authors found that about 103,000 GWh energy could be produced from waste per annum and this generation would be able to reduce about 6.5% of the carbon footprint annually in the region [52]. In another study, an overview of solid waste management in the MENA region was presented [93]. In contrast, our study focused on selected countries in Sub-Saharan Africa and South Asia, and thus justifies the novelty of the work. In addition, waste generation is going to triple (174 to 516 Mt/yr) and double (334 to 661 Mt/yr) in 2050 compared to waste generated in 2016, respectively in these selected countries in the regions [1]. This study also provides detailed insight into a successful WtE plant in a developing country, Bangladesh, and highlights the opportunities, challenges, and future policy requirements for WtE plants in developing country context.

4. Analysis and Results

Figure 4 shows that waste composition in the SSA developing countries (lower-income countries) is dominated by organic components, implying proper selection of waste management schemes in these countries. The proportion of recyclable components of waste, such as glass and metal, is very low in these countries. Although the majority of waste in the developing world is organic, its treatment procedures vary between countries. Exploring the reasons for different treatment procedures in different developing countries is beyond the scope of this work.

Figure 5 depicts that average values for organic waste content for developed and developing countries are about 32% and 50%. There exists a positive relation between waste generation and the income level of a country. Daily per capita waste generation will increase by 40% and 19% for developing and developed countries by 2050. Among these developing regions, SSA and SA are fast-growing. The projection shows that 516 and 661 Mt of waste per year will be generated in SSA and SA in 2050.

If Figure 4 is compared with Figure 5B, the waste is dominated by organic components. In developing countries, on average, 30% of waste content is in the ‘other’ category, that is, mixed wood, garden, leather, and rubber. For developed countries, the average value is 22%.

Most developed countries have this ‘other’ type of waste content of about 30% (see 75th percentile of ‘other’ in Figure 5A), whereas the majority of developing countries have this content of about 51% (see 75th percentile of ‘other’ in Figure 5B). The main reason for this waste content variation is that in the developed world, wastes are separated at source (e.g., at residences), which is not the case for developing countries.

For the developed countries the average proportions of paper and plastic are 21% and 12%, respectively; in developing countries, the figure for paper content is more than two times less than that for developed countries (9%), and it is 8% for plastic. The percentages of the remaining two waste components glass and metal are below 10% for both developed and developing countries.

Globally, the open dumping waste treatment practice represents about 31% of waste and is dominated by developing countries [1]. Of which, about 93% of waste is openly dumped in the developing world, whereas only 2% of waste is dumped in developed countries [1]. For the selected developing countries, the existing waste treatment practices are depicted in

Table 3. Waste treatment practice in selected developing countries in Sub-Saharan Africa and South Asia. (Data Source: [33]).

Country	Anaerobic Digestion (%)	Incineration (%)	Recycling (%)	Compost (%)	Controlled Landfill (%)	Landfill Unspecified (%)	Sanitary Landfill-Gas System (%)	Open Dump (%)	Other (%)	Unaccounted (%)
Ethiopia	0	0	0	0	0	0	0	43	0	57
Uganda	0	0	6	0	0	0	7	87	0	0
Mozambique	0	0	1	0	0	0	0	99	0	0
Guinea	0	0	5	0	0	0	0	0	0	95
Benin	0	0	25	0	0	0	0	0	0	75
Niger	0	0	4	0	0	0	0	64	12	20
Togo	0	0	2	1.8	0	0	0	96.2	0	0
Zimbabwe	0	0	16	0	0	0	0	0	0	84
Burkina Faso	0	0	12	0	0	17	0	59	0	12
Senegal	0	0	0	0	5.1	0	0	43.8	4.7	46.4
Bangladesh	0	0	0	5.25	0	0	0	0	0	94.75
Bhutan	0	0	0.86	1.39	97.75	0	0	0	0	0
India	0	0	5	18	0	0	0	77	0	0
Maldives	0	6	0	7	0	0	0	63 *	24	0
Sri Lanka	0	0	12	5	0	0	0	83	0	0
Nepal	0	0	0	2.87	0	37	0	0	0	60.13
Pakistan	0	0	8	2	0	40	0	50	0	0

Note: Data were not available for Burundi, Chad, Comoros, The Gambia, Mali, and Afghanistan. * Waste treatment/dump in water ways/marine.

. Most developing countries practice open dumping for waste management except Bhutan, which uses controlled landfills as its main waste treatment strategy. For many developing countries, the waste treatment method is not well known. For instance, 94.75% and 84% of wastes were found unaccounted for in Bangladesh and Zimbabwe. Most of these countries do not use commercially available technologies, such as anaerobic digestion or incineration, to treat their wastes. In terms of ‘landfill unspecified’ waste treatment, Pakistan (40%), Nepal (37%), and Burkina Faso (17%) practice this method. The majority of the developing countries listed in Table 3 also recycle to some extent. Only Benin was found to recycle about 25% of its waste. Despite the open dumping method used by Uganda, the country also practices a ‘sanitary landfill-gas system’ for 7% of total waste.

If Table 3 is compared with Figure 4 and Figure 5B, it can be seen that due to the mixed type of waste, most developing countries practice open dumping for waste management, because source separation of waste in developing countries is rare.

The WtE generation process involves many different costs for different types of plants. Among four different processes—incineration, co-processing, anaerobic digestion, and landfill gas—all costs are higher for incineration than others. For comparison purposes, costs for different WtE generation technologies are presented in

Table 4. Cost comparison between WtE generation technologies (Data source: [94]).

Technology	Initial Investment Cost (Million EUR)	Capital Cost Per Ton (EUR)	O&M Cost Per Ton (EUR)	Total Cost Per Ton (EUR)	Cost Per Ton Waste Input (EUR)	Capacity (t/yr)
Incineration	30–75	22–55	20–35	42–90	40–80	150,000
Co-processing	5–25	10–25	10–20	20–45	19–40	50,000
Biogas (Anaerobic Digestion)	12–20	12–19	10–15	22–34	14–18	50,000–150,000
Landfill Gas	5.3–6	0.8–1.4	0.3–0.8	6–7	0.8–1.7	390,000–850,000
Alternative Technologies	680–120	35–45	30–40	65–85	63–80	200,000

Note: Each technology was considered with 20 years of operation and a 6% annual interest rate except landfill gas, for which the years of operation was 21 and the annual interest rate was 12%.

. Please note that the cost for different technologies presented in the Table 4 might vary based on the resource’s availability, waste processing, and other taxes imposed by local governments in every country.

Table 4 shows that the total cost per ton of waste processing is lower for the landfill gas method than other available technology, but this technique is not environmentally friendly. The next lowest cost is for biogas production through AD. Although AD is a suitable technology for wastes dominated by organic components in developing countries [19], the first waste to energy plant that was installed in Ethiopia in 2018 was an incinerator [95]. In contrast, Bangladesh began the first waste to energy plant in Jashore based on AD technology [37]. Although this was a good start in WtE generation for the country, there are several challenges that need to be overcome through proper policymaking. To provide a detailed insight into the WtE project in Bangladesh, this project is presented as a case study.

5. Discussion and Policy Implications

Food and green waste in developing countries varies between 53% and 57%. There is an inverse relationship between the increase of organic waste and the country’s economic development. In the developing world, only 20% of waste generated could be recycled. In contrast, about 51% of waste could be recycled in the developed world. Waste generation and collection for treatment vary significantly in developed versus developing countries. Waste collection rates of upper middle income to high-income countries vary between 82% and 96%. In developing countries, this rate varies between 39% to 51% [1]. Waste collection and the disposal or recycling process also depend on the per capita GDP of the country. It was found that a proportional relationship exists between per capita GDP and waste collection and disposal standards. For instance, if per capita GDP is less than EUR 2,000, the waste collection is very limited, and the disposal method is open dumping. In contrast, when per capita GDP is greater than EUR 10,000, the waste collection rate is very good, and the wastes are separated at the sources and latest WtE generation technologies, such as incineration, pyrolysis, AD is used. These are illustrated in Figure 6.

In South Asia (SA), about three-fourths of waste is openly dumped; of which, about 44% is collected through a door-to-door system and about 57% of waste is characterized as organic waste containing food and other green waste [1]. Similarly, in Sub-Saharan Africa (SSA), about 69% of waste is openly dumped. About 40% of the generated waste is organic and the overall waste collection rate is about 44% [1].

In terms of waste composition for the selected countries in the SSA, it contains 35 to 87.50% organic waste in their total waste except for Burkina Faso, Mali, and Senegal. On average the organic component is about 48.70%. On the other hand, the organic component of the total waste in the countries in SA varies between 24% and 80.58%, and the average is about 51.16%. Only Maldives has an organic waste component of 24%.

In Ethiopia, the first waste to energy power plant, an incinerator, was established in 2018, the first in SSA [95]. However, it was also reported that the incinerator, as WtE generation technology, is not suitable for Ethiopia, as well as Africa because it is an expensive and inefficient technology; as it burns waste it emits NO_X, mercury, dioxins, and other pollutants, it undermines the sustainable zero waste practice, it threatens jobs and harms environmental justice [96]. It was also recommended that current waste streams must be investigated to identify a suitable waste management scheme.

The present analysis suggests that the domination of organic waste in the total waste of developing countries in SSA and SA is suitable for the anaerobic digestion (AD), and it could be an effective solution towards WtE generation as reported in [19]. However, proper guidelines must be followed for the WtE plant establishment [98].

Based on the analysis conducted, considering geographical location, waste composition, collection methods, and recycling, WtE generation offers several opportunities along with some challenges in the developing world. These are illustrated through a case study in the following section.

5.1. Waste to Energy Generation: The Case of Jashore, Bangladesh

Jashore is the main city of Jashore district in the Khulna division and is located in the south-western part of Bangladesh. The area of Jashore district is about 2607 sq. km., of which, the territory of Jashore city and Paurashava are 28.56 and 14.71 sq. km, respectively [99]. The annual average temperature of Jashore varies between 11 °C and 37 °C with an average annual rainfall of about 1,537 mm. Average humidity is about 78% [36].

According to a recent feasibility study on waste to energy conversion in six municipalities in Bangladesh including Jashore, it was reported that the average waste generation rate in Jashore in 2020 would be 0.27 kg per capita. Average daily and annual waste production in the same year would be 60 t/d and 22,078 t/yr, respectively. If a collection rate of 75% is considered, daily and average annual waste treatment should be 45 t/d and 16,558 t/yr [36]. The same study also investigated waste composition in five other cities, and the average was considered to be Bangladesh’s waste composition for this study. For both Jashore and Bangladesh (the average of six cities), the waste composition is illustrated in Figure 7. It can be seen that the organic component of waste not only dominates the waste in Jashore city but across the country.

Similar to other developing countries, the dominant portion of waste generated in Bangladesh is organic waste, with a range between 68% and 81% [100]. Wastes in Bangladesh contain about 60%, 26%, and 18% of water, combustible components, and ash, respectively [19]. Waste could be used for direct combustion without any auxiliary fuel if it contains at least less than 50% water, 25% or more combustible components, and less than 60% ash [101]. Thus, wastes in Bangladesh are not suitable for combustion as they contain more than 50% water due to the dominance of organic waste. A solution to this problem is anaerobic digestion to treat wastes with high water content, and this was found to be sustainable for developing economies [19].

Considering the waste characteristics of Jashore, a pilot project titled Integrated Landfill and Resource Recovery Center (IL&RRC) was designed by the waste concern consultants in 2016. It was financed by the Asian Development Bank (ADB), German Development Bank, and Swedish Development Co-operation Agency. The IL&RRC started operating in November 2019. The IL&RRC is able to recycle waste into biogas, electricity, and fertilizer, and is the first of its kind in Bangladesh.

In IL&RRC, organic waste materials, such as fruit and vegetable peels, are recycled into fertilizer, and this process takes 28 days. This organic waste material sorting is completed with a mechanized sorting unit with the capacity of a half-ton per hour. A box system with forced aeration and a mechanical dryer are used for the composting process, with a capacity of 20 t/d [102]. The remaining waste portion is used for anaerobic digestion and biogas is produced. The four biogas plants have the capacity of about 18 t/d. This biogas is then used to produce electricity. The waste components, which are not decomposable, and leachate go to controlled landfill areas. The production capacity of the plant is listed in

Table 5. Integrated Landfill and Resource Recovery Center’s (Jashore) maximum and present production capacity (Data source: [37] & TV report (https://www.youtube.com/watch?v=zxtn3gy3-1U (accessed on 22 April 2020))).

Product Type (Unit)	Maximum Production Capacity	Present Production Capacity
Fertilizer (t/d)	4	1–1.5 *
Biogas (m3)	720	450
Electricity (KW)	550–600	200

* Present waste input is about 20 t/d.

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At present, the 200 KW electricity generated is being used to run the IL&RRC. If more waste could be ensured, the electricity generation would be increased to its maximum rated capacity and this additional electricity could be supplied to the national grid. Although the IL&RRC is operating well, there is a lack of national and local policies related to waste to energy generation. The major policies and laws that are related to waste management in Bangladesh are listed in

Table 6. Waste management-related policies and acts in Bangladesh (adapted from [103]).

Year	Policies/Acts	Comments
1995	Bangladesh Environmental Conservation Act	Recommends standards for disposal of different types of waste.
1998	Urban Management Policy Statement	Recommends the municipalities for privatization of services as well as giving priority to facilities for slum dwellers, including provisions of water supply, sanitation, and solid waste disposal.
1998	National Policy for Water Supply and Sanitation	According to this policy, the government shall take measures for recycling waste as much as possible and use organic waste materials for compost and biogas production.
1999	National Agriculture Policy	According to this policy, the government will promote the use of compost/organic fertilizer amongst the farmers to improve soil productivity and food security.
2005	National Industrial Policy	This policy is recommended the use of environmental management systems and cleaner production practices amongst industries.
2006	Fertilizer Act	Under this act, compost has been promoted and a standard of compost has been set by the government.
2006	National Urban Policy	Clean development mechanism (CDM) and recycling have been emphasized in this policy.
2008	National Renewable Energy Policy	This policy is promoting the production of biogas and other green energy from waste and providing incentives, such as CDM, to promote green energy projects.

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Table 6 shows that there is no specific policy for waste to energy generation in the country. This finding is in line with a recent study, where the authors investigated all the available waste management-related policies, acts, and regulations of Bangladesh and found that the present waste management policy does not have any WtE recovery targets [100].

The challenges that are facing the implementation of the national 3R (reduce, reuse, recycle) strategy for waste management in Bangladesh are also applicable for WtE generation projects [104,105]:

• New policies need to be issued to attract private investors in the waste to energy sector.
• It is essential to ensure inter-ministerial coordination to facilitate WtE initiatives and public-private partnerships.
• Lack of local, technically skilled manpower to establish WtE generation projects.
• Lack of financial resources with respect to WtE generation projects.
• Awareness of people and the capacity of government and the private sector needs to be improved for WtE projects.
• Enhancement of research, development and capacity building are essential.
• Source segregation of waste is very low or unsatisfactory in Bangladesh. Thus, this needs to be implemented.
• Inefficient waste collection method.

5.2. WtE Generation and Sustainability

In terms of sustainable development, the WtE generation option provides several positive and negative impacts, listed in

Table 7. Impacts of WtE generation on sustainability in the developing world compared to open dumping and landfill without gas recovery (authors’ analysis).

Sustainability Dimensions	Positive Impacts	Negative Impacts	Dominant Impact Type
Social	Public health improvement Odor reduction Reduction of waste Local renewable energy generation Benefits to the local community	Increased noise and dust due to waste transportation vehicles	Positive
Economic	Local economy development New job creation Avoidance of disposal cost	Local land value might be increased	Positive
Environmental	Reduced air pollution Reduced odor pollution Less use of fossil fuels Renewable energy generation Use of by-products as fertilizer	Emissions from WtE plants	Positive

. Although there are some negative impacts of WtE generation plants, positive impacts dominate towards sustainable development.

WtE generation offers many social, economic, and environmental advantages. However, to ensure all of these benefits proper technology selection is a precondition. Thus, any WtE plant planning at a particular location needs a pre-assessment study.

5.3. WtE Generation Challenges

From the analysis, literature survey, and the case study considered, it is evident that to implement a WtE generation plant in any city of the developing world, some challenges need to be faced.

• The first challenge is the composition of waste, which is dominated by organic components [106]. The waste generated in developing countries, such as in India, are very distinct compared to those in the developed world due to their compositional characteristics (high moisture content and low calorific value) and has an immediate impact on the efficiency of power generation [107,108].
• Generated waste separation at source is a major challenge for developing countries [46]. The same finding was also reported for Bangladesh [104,105], and India [108]. This is due to the absence of a well-organized waste management system. For example, a 6 MW capacity WtE plant in Lucknow, India based on biomethanation failed due to the absence of waste separation at the source [109].
• Effective waste collection method is another challenge for WtE generation, as no such method exists in most cities in the developing world [105], such as in Nigeria [44]. Most cities use the conventional waste management system: ‘we dump—they collect’ is the general practice in residences, due to lack of a proper strategy and policy [103]. Insufficient collection of waste was also found to be a major challenge in India [108].
• Negative experiences from previously implemented waste management projects [49].
• Lack of suitable WtE generation technology and skilled manpower to establish and operate a WtE generation plant [50]. One of the major challenges is that a technology that is found to be efficient and effective for the developed world might not be suitable for developing countries [110]. “Cleaner and efficient technologies are found to be comparatively more expensive than dirty and cheap technologies” [103], thus, difficult for the developing economies to be adopted.
• Insufficient financial support to implement and operate WtE generation projects. Most city corporations or municipalities in developing countries have fewer financial and human resources to deal with waste management, such as in India [108] and Bangladesh [103]. In India, 5 WtE plants faced operational problems due to insufficient financial as well as logistic support planning [109].
• Lack of coordination between different sectors of the government, that is, the absence of institutional capacity building. Research shows that institutionalized failure, along with ineffective urban policies and regulations, are the main factors for waste mismanagement in developing countries, such as South Africa [111] and India [108].
• Lack of private sector participation in WtE generation projects. Insufficient or no incentives for private sector involvement [105]. It was found that coordination between different ministries and the private sector could be beneficial [100].
• Absence of local as well as national energy policy, and rules and regulations concerning WtE generation. For instance, to address the potential negative environmental impacts that might arise from building and operating WtE generation plants, no regulatory framework exists in Nigeria [44]. It was found that the lack of political will and proper knowledge are hampering the adoption of positive changes towards effective waste management and related policy development [111].

5.4. WtE Policy Development Steps

For sustainable waste management and energy generation, policy development needs to focus on different levels of the waste management system. Considering its negative environmental and public health impacts, the disposal of waste must be controlled. This is important as ‘environmental protection is still relatively low on the public and political agenda in many developing countries’ [112]. One such solution is recycling and energy recovery from waste, but this requires appropriate technological solutions.

Effective waste management should include reuse and waste minimization, for which integrated policy is essential. This must ensure two features: sustainable waste management and renewable energy generation from the waste. Such policy should also include the prevention of waste, such as polyethylene grocery bags, as it is a direct threat to the environment and is difficult to manage. To implement this policy, the authority should set targets with proper time frames. If all these steps can be implemented, a sustainable waste management system can be assured with maximum energy recovery. All these steps are illustrated in Figure 8.

Steps (2) and (3) in Figure 8 are crucial for waste to energy generation in developing countries. Therefore, actions related to these steps should be the highest priority for the country’s government to consider first, when planning for a WtE plant.

Considering all the aspects discussed, a successful WtE generation project must follow a step-by-step procedure for effective implementation. These steps are illustrated in Figure 9.

Assessment of the composition of generated wastes is the first step. Organic materials, such as kitchen wastes, predominate in developing countries. In contrast, inorganic components, such as plastics and paper, form the major proportion of wastes in the developed world.

How wastes will be collected for the WtE generation plant needs to be answered for its smooth operation. In developing economies, organic and inorganic wastes are not separated at source, and this needs to be ensured for any WtE plant’s use of raw materials. It is also necessary to confirm systematic waste collection for the smooth operation of the WtE plant and arrange waste or residue transportation.

The next step is to select the appropriate technology for the WtE generation plant, including the calorific value of the generated wastes (for thermal plant), the quantity of wastes required daily, and the efficiency of operation of the plant.

Financial resources, such as investment costs and operation and maintenance costs, must be arranged in advance for proper implementation and smooth running of the plant. Additionally, training for the staff must be arranged to develop their skills for the establishment, operation, and maintenance of the plant.

For successful implementation of a WtE generation plant, this option must be included in the local as well as the national energy policy. Furthermore, the government should promote WtE generation options by providing incentives to the organization or institutions who are interested in establishing the plants.

5.5. Policy Implications

This analysis found that most SA countries (except Pakistan) have their own laws governing solid waste management (SWM). They also have public-private partnership (PPP) rules and regulations related to solid waste management (SWM). Each of these countries has its own national agency to enforce SWM laws and regulations. Although these countries have law enforcement agencies and regulations, the waste treatment processes are not environmentally friendly, as most practice open dumping (see Table 3).

On the other hand, out of 15 countries in the SSA region, 11 have national SWM laws. Only four countries have law enforcement agencies for SWM. Six countries have PPP rules in relation to SWM. None of these countries considered waste as a source of energy until 2018.

In contrast to the Ethiopian incineration WtE plant [95], Bangladesh developed its first AD-based waste to energy plant in Jashore, which began operating in 2019. Before the establishment of the plant, a feasibility study was conducted to check local waste types, suitable technologies, and other necessary parameters. The plant still faces several challenges, such as waste separation, fees for waste collection, and local and national policy development for its smooth operation. A recent study thoroughly investigated all the available waste management related acts, policies, rules, and regulations of Bangladesh and found that ‘none of these acts, regulation, or policy do not address any specific target of achieving waste disposal, composting, energy recovery, Clean Development Projects (CDM) projects’ [100].

Considering the analysis presented in this study, several policy implications could be drawn for any WtE generation plant for developing countries in SSA and SA.

• Although there is the potential of WtE generation in Bangladesh, the power system master plan [113] of Bangladesh did not consider this option extensively [7]. Other developing countries, such as Thailand, included waste as a potential source of energy in its national energy policy and development plan, which is estimated to be 4,390 MW in capacity [114]. Of this capacity, 160 MW would be generated from different wastes and the rest would be from biomass (3,630 MW) and biogas (600 MW). A national energy policy should include a WtE generation option in the renewable generation category to emphasize its maximum practice [115]. Thus, related rules, regulations, and technical standards with respect to the country’s economic conditions must be established [50]. A detailed legislative framework might be helpful for this.
• Municipalities must include waste management targets in their city plan, and these should consider WtE generation strategies and action plans. As a part of the action plans, municipalities should ensure local financing options for the smooth operation of the WtE plants and possible future expansion. This will ensure a decentralized operation of the WtE plants and underpin to avoid complete dependency on the national government’s budget [57].
• The use of WtE technologies has positive impacts on society, economy, and environment. Despite these positive impacts, it would be impossible for most developing countries in SSA and SA to adopt the WtE technologies within a short period because of the capital cost needed for the establishment of the project [116]. A long-term plan should be initiated for this purpose and the local authority, as well as the government, should ensure funding for the WtE plant for its complete establishment and smooth operation. Technical skills of local government need to be strengthened to implement more similar projects in the future.
• The private investors in most of the SSA and SA countries might be hesitant to invest in any new type of project, such as WtE, due to the non-market financial risk and other related uncertainties. The government should take the initiative in involving private investors in WtE generation projects [117]. Diversification of financing mechanisms could be an option for the success of a WtE plant establishment. Different well-established business models might be used for this purpose, such as build-operate-transfer or public-private partnership [50]. However, the business model adopted must follow transparent and corruption-free operation. It was found that lack of transparency and corruption were the two crucial reasons for the failure of a WtE incinerator PPP project in China [49]. The government did not disclose the complete financial and environmental reports and pollutant emission data on a regular basis to the public, and this created a transparency problem of the project. In terms of corruption, a strict tendering process was not followed for the WtE plant; thus, the project was implemented by non-professionals. This might be possible through bribery or illegal forms of solicitation and a common scenario in the developing world, including China [49].
• A feasibility study for the WtE generation plant must be conducted to identify the most suitable technology for waste type, local needs, the environment, and sustainability. For example, a study in Nigeria evaluated WtE generation potential in 12 cities and found that a combination of anaerobic digestion and incineration has the highest potential to generate electricity from waste [44]. Considering waste type and sustainability of WtE generation technologies, another study found that anaerobic digestion is most suitable in developing economies, such as Bangladesh [19]. These two examples clarify how WtE generation technology might vary from one country/region to another. For a country, city, or region-specific area, a feasibility study should be conducted before the WtE project implementation.
• Before the implementation of any new WtE plant, it is vital to assess the continuous flow of feedstock for uninterrupted operation. This is because, for a small city with a population of about 300,000, it is difficult to gain economic benefits from a WtE plant. For instance, it was reported that a WtE plant in China with a capacity of less than 300 t/d is unable to receive reasonable economic benefits [50]. ‘The amount of wastes available for energy recovery is an important factor directly affecting the energy and environmental benefits of waste utilization’ [118]. For any developing country in SSA or SA, it is recommended to assess the regular waste generation rate and economic feasibility of the proposed WtE plant.
• In the local context, a holistic cost-benefit analysis needs to be conducted for any proposed WtE plant [119].
• WtE generation planning must take into account future changes in waste composition, as the plant’s future operation will be dependent on waste feedstock, as waste composition and distribution vary from one location to another due to demographic, economic, and industrial factors [120]. Lu et al., (2017) found that due to the ‘particular elemental compositions of Chinese MSW, the WtE plants in China are substandard with respect to emissions [121]. A new waste recycling policy development might have an impact on the waste feedstock of the plant.
• Several failures of WtE projects in developing countries were found due to the lack of proper infrastructure, pollution control, regular maintenance, and logistical planning [109,122]. The local municipality should develop proper monitoring, maintenance, and regulatory plans for the plant.
• In light of international emission standards [49,98] for WtE plants, national emission standards need to be set before implementation [50]. One study showed that ‘an inadequate dioxin-control strategy due to less stringent standards, along with poor monitoring practices’ was a crucial reason for the unsuccessful WtE incinerator project in Huizhou, China [49]. How these emissions may change in the future also need to be considered. An emissions monitoring authority along with proper rules and regulations must be established.
• An environmental and social impact assessment must be conducted for any new WtE plants, as this type of plant might impose more threats to the local environment than a typical power plant. A study in China found that most of the incinerators are substandard regarding emissions and one of the reasons for this was found to be insufficient funds for compliance with the national and international emission standards [121]. The emission standard can be assured if a proper environmental impact assessment is conducted before the plant is implemented, considering all possible impacts. Lack of guidelines to conduct an environmental impact assessment with respect to WtE projects is another common scenario in the developing world [98]. A social impact assessment of any project does not receive sufficient attention compared to economic impacts in developing countries [123]. In India, the expansion of a WtE plant (16 MW to 40 MW) in Delhi faced public protest as the residents were concerned about health hazards, such as respiratory diseases due to the toxic emission [124]. Improper social impact assessment before the implementation of the project might be responsible for this. Governments of the countries in SSA and SA should take necessary steps to conduct proper social as well as environmental impact assessments of any proposed WtE plant.
• Country-specific enablers and barriers related to WtE plant establishment need to be identified as South Africa did for their WtE industry [125]. This will underpin firm policymaking towards sustainable WtE generation projects.

6. Conclusions

A rapid review along with an analysis was conducted, focusing on waste quality and composition in the developing world, and opportunities and challenges were identified. It was found that waste in developing countries is dominated by organic components. A majority of developing countries in SSA and SA use the open dumping method for waste management.

For most developing countries including all regions, the organic portion of waste varies between 35% and 67% with an average of 50%. Whereas, on average, about 48.70% and 51.16% of waste generated in developing economies of SSA and SA are organic. For developed countries, this range was found to be 23–43% with an average of 32%. This waste composition also underpins the decision to select a proper WtE generation technology. The domination of organic components in the total waste of SSA and SA countries indicates that anaerobic digestion could be a potential solution for WtE generation towards a sustainable waste management system. The next dominating component in the waste composition was the ‘other’ category, including wood, green waste, leather, and rubber. In developing countries, the ‘other’ range varies between 10% and 51% with an average of 29%, whereas this figure was 12–30% with an average of 22% for the developed world, where waste is separated at source.

Lack of proper policy and regulations are hindering the progress of WtE technology adoption in SSA and SA countries. Lack of financial support and insufficient technically skilled personnel were found to be the two crucial challenges for WtE technology development in the developing world. If these issues can be solved for these countries the waste would become a resource rather than a risk. The findings from this study could be helpful for the policymakers, researchers, and technical personnel in the field of electricity generation and sustainable development to get an insight into waste management practices and WtE generation opportunities in developing countries.

Although this rapid review along with the analysis sheds light on WtE generation opportunities and challenges in the developing countries, the analysis did not cover all developing countries predominantly due to data limitations, and further research is indicated.