Life Cycle Assessment of Municipal Solid Waste Management within Open Dumping and Landfilling Contexts: A Strategic Analysis and Planning Responses Applicable to Algeria

Abstract

This paper examines Municipal Solid Waste (MSW) Management with a high organic matter content employing the Waste and Resource Assessment Tool for the Environment (WRATE) and the Ecoinvent database, by conducting a Life Cycle Impact Assessment (LCIA). Four scenarios, aligned with Algeria’s National Waste Management Strategy, are analyzed as case studies. LCA results identify the baseline scenario (current state) as the worst case. Significant improvements (84% reduction in climate change impact) are observed for scenario 2 to 4, which incorporate methane capture and energy recovery. Likewise, acidification potential was reduced, while eutrophication balanced positively for scenario 1 to 3 and negatively for scenario 4, promoting sustainable practices. This study proposes an optimal solution where the MSW service covers the charges and starts generating profit by shifting from a flat rate of 2000 Algerian Dinars (DZD) per household per year to 1% of household income. This change aims for at least 41% cost recovery from citizens at the national level, with minimum recovery targets for composting (50%), recycling (25%), and efficient landfilling (15%), alongside 20% energy recovery. To align with the Waste Hierarchy priorities, the Algerian government should gradually restrict organic waste landfilling (54% of MSW) and promote composting. Additionally, Algeria should establish regulations to encourage recycling programs, such as implementing Extended Producer Responsibility (EPR) regulations and setting recycling targets for various waste streams.

1. Introduction

Due to fast population growth and urban sprawl, the generation of household solid waste (HSW) has increased considerably in the last few decades [1,2]. Landfilling remains the preferred solution for substantial waste elimination due to economic factors and a lack of technical expertise in other alternatives [3]. As a result, inadequate solid waste management is the head of problems that affect human and animal health [4]. It has substantial consequences, resulting in economic and biological losses [5]. In 2016, the MSW management sector produced approximately 1.6 × 10⁹ metric tons of greenhouse gases (GHG), measured in CO₂ equivalent (CO₂-eq), accounting for 5% of the world’s total CO₂ emissions [6]. Furthermore, in 2014, inadequate landfill disposal practices contributed to 15% of greenhouse gas emissions in developing economies [7].

Assessing waste management policies is a complex process that implies environmental, technical, economic, and social factors. Approximately 50 tools have been developed since 1974 to support waste management decision-making [8]. Among several tools, such as cost-benefit analysis (CBA), multi-criteria decision-making (MCDM), or optimization frameworks), life cycle assessment (LCA) has been widely used in developed [9,10,11,12] and developing countries [3,13,14] to estimate the life cycle impact of waste management and to compare and optimize solutions. The composition of waste has a significant impact on the LCA of waste management [15,16]. Hence, obtaining precise and relevant data plays a crucial role in reducing uncertainties and improving the accuracy of results. A notable example of this challenge can be observed in the European Union (EU), where an erroneous estimation of future waste generation trends was a common mistake in waste management planning. Consequently, waste processing facilities such as incineration or composting plants were often overestimated in terms of their capacity requirements [17].

Unlike the affluent Gulf Cooperation Council (GCC) countries, the majority of middle-income Middle East and North Africa (MENA) nations have a high percentage of organic fractions share [18] and exhibit almost identical demographic and socio-economic characteristics [19]. These densely populated countries face significant challenges due to the improper disposal of MSW, which is predominantly managed through open dumping and inadequate landfilling practices [20]. Additionally, with the exception of Lebanon and Iran [3,21], there is a noticeable scarcity of Life Cycle Assessment (LCA) research providing in-depth analysis in the middle-income MENA region.

Algeria is the biggest country in Africa with a total area of 2,381,741 km²; it has a strategic location in the North of Africa facing Europe, bordered to the North by the Mediterranean Sea, by the east by Tunisia and Libya, to the southeast by Niger, and to the southwest by Mali. In 1994, Algeria’s population was 28 million; it increased to 33 million in 2004 and 45 million in 2022, according to the National Office of Statistics.

The change in the Algerian MSW composition in the last two decades has been remarkable. For instance, in Mostaganem, a city in the north west part of the country, between 1983 and 2004, organic matter decreased by about 17%, passing from 78% to 64.6%, while paper-cardboard and plastic increased to 26% and 29%, respectively [22]. Similarly, from 2000 to 2018, the national waste composition has changed permanently, as reported in the Supplementary Figure S1a, and organic matter has decreased by about 20%, passing from 74% to 54%. Paper-cardboard increased from 7% to 10%, and plastic proportion passed from 3% to 17% [23]. This change in the nature and type of MSW (increases in paper and plastic at the extent of organic matter) is the consequence of the excessive rural exodus, the international free trade, and the introduction of a new consumer habit among Algerian citizens’ tending to the lifestyle of industrialized countries [22,24,25]. In such a case, the uncertainty in waste management LCA arising from change in the waste composition may influence the environmental assessment of waste-management solutions. Slagstad et al. [16] Showed that a ±15% change in the large fractions (paper, plastic, and food waste) results in a more than 10% change in global warming, nutrient enrichment, and human toxicity via water impact categories. Nevertheless, this is possible only with dedicated waste LCA tools like EASETECH [26,27], WRATE [28], and SWOLF [29] which, unlike products LCA software (e.g., SimaPro, Open LCA, and GaBi), account for the individual material fractions.

Indeed, the rural exodus and the rapid urbanization resulted in a constant shortage of housing and the appearance of gigantic slums around the main towns [4,30,31]. During the black decade (1992–2002), the rural population decreased from 50.3% of the total population in 1987 to 40% in 1998, as shown in Figure S1b. In 2015, the Algerian rural community represented only 29.27% of the overall population [32]. This massive urbanization has changed the Algerian population’s consumption habits to make it more and more accessible to more manufactured products. Rapid population growth and forced urbanization have been accompanied by an immediate increase in MSW generation and a change in its fractions. The amount of MSW doubled from 10 million tons in 2004 to 22 million tons in 2014, as indicated in Figure S1b. In terms of MSW management, in 2019, 56% of MSW was openly dumped and burned in the open air in public dumps, 36% was landfilled, 7% recovered, and only 1% composted [23]. Consequently, the GHG emissions of the waste sector in Algeria represent 10.29% of the overall national GHG emission. Of this GHG, 66% is related to inadequate waste deposition and landfilling. Thus, according to the National Action Plan for Environment and Sustainable Development (NAPE-SD), the cost of environmental degradation is estimated to be 0.32% of the Gross Domestic Product (GDP), making the enhancement of Solid Waste Management a national priority. The Algerian government has chosen to eliminate progressively MSW by landfill technique. One of the MSW Management National Program’s (PROGDEM) objectives was to abandon the traditional model of eliminating waste in open dumps and promote recycling activities. In 2014, 272 landfills were completed, increasing the landfilling capacity to 36%; the open dumping has decreased to 46%, and the recovery capacity has risen to 10%, as reported in Figure S1c. In 2018, more than 300 landfills were completed, and 85% of the uncontrolled landfills in the country have been eradicated.

Financially speaking, the current MSW management system allows coverage of only 2% of the total waste management budget, estimated to be 36.3 billion Algerian Dinars in 2017 [33]. The main causes of this deficiency are the low amount of recycling, the neglectable quantity of composting, and the poor waste collection charge recovery. Thus, One can achieve financial equilibrium only when the waste collection charge is majored to 1% of the household revenue with at least 41% recovery at the national level, 50% of MSW is composted, 25% is recycled, and 25% is properly landfilled with good energy recovery [33].

Four scenarios taken from Algeria’s National Solid Waste Management Strategy have been used as a case study [33]. The study’s scope is applicable to nations with similar municipal waste characteristics and strategic municipal waste management orientations.

The purpose of this article is to evaluate Algeria’s waste management strategy from a neutral standpoint, along with potential alternatives. This is accomplished, in particular, by critically analyzing the Algerian visions (horizon 2035).

The subject of managing MSW is addressed in this article from three angles: ecological, technical, and economic. It analyzes MSW management situations through a life cycle assessment study. The associated footprint is evaluated in line with the UN’s declared sustainable development objectives, specifically SDG 11.6 and 12.

This paper also evaluates the sensitivity of LCA results to temporal changes in waste composition and the implications they have on projected waste management solutions. Finally, this paper suggests a critical reading of the Algerian National Waste Management Strategy 2035, by assessing the technical, social, economic, and environmental aspects and exploring potential GHG emission mitigation approaches in alignment with the ongoing reform of the waste management system in Algeria.

2. Materials and Methods

The objective of this study is to analyze the current and orient the projected waste management solutions outlined in Algeria. To achieve this, we first establish a representative waste management system for an average Algerian city based on reliable waste composition data. Subsequently, we model the environmental impact of the present and projected waste management systems using the four scenarios described in the 2035 National Waste Management Strategy [33].

The life cycle assessment (LCA) of waste management for a typical Algerian city follows the guidelines provided in ISO 14040 and ISO 14044 [34,35]. The LCA was conducted using the Waste and Resource Assessment Tool for Environment (WRATE) software academic version 3.0.1.7 [36] and the Ecoinvent database (version 2) for background data (Figure 1). The electricity mix assumed in the study aligns with the Algerian situation, where fossil fuels and natural gas are the primary energy sources. Results from the Life Cycle Impact Assessment (LCIA) have been normalized to the unit of “European person equivalent” [37], defined as the number of “average” people that would cause the same impact over the course of a year [38]. Aggregated results have been obtained by the summation of the normalized results of all impact categories. Aggregated results do not present a physical sense, but enable a comparison among several scenarios allowing their classification in terms of global environmental effect [39,40]. Despite the fact that “European person equivalent” is not a conventional unit, this parameter is useful for a better comparison among the scenarios, and its suitability is recognized in the literature.

The foreground system, depicted in grey in the supplementary information Figure S2, includes emissions from various waste treatment facilities studied, such as open dumping, landfill (with and without energy recovery), composting, and materials recycling facility (MRF). The background system encompasses the supply of electricity, diesel, and other materials like single-use polyethylene plastic bags and plastic bins to the foreground system, contributing to indirect emissions.

One methodological choice we faced was the selection of waste composition for this study. Comparing results across national-level waste characterization studies is challenging due to the scarcity of such studies and the use of different characterization methodologies [28,41]. To address this issue, we utilized waste composition data provided by the National Waste Agency for the years 2000, 2007, 2010, 2014, and 2018, which were characterized using the widely accepted French Method for Characterization of Domestic Waste “MODECOM^TM” (MODE de Caractérisation des Ordures Ménagères) [42], as shown in Figure 1. This standardized and reliable dataset ensures accurate and consistent analysis of waste management practices in Algeria, enabling the formulation of effective policies and strategies for sustainable waste management. The functional unit for the LCA was defined as 1 million tons of MSW, representing the waste managed by the Waste Disposal Authority in an average Algerian city responsible for implementing the local waste management strategy.

2.1. Senarios’ Definition

Four gradual scenarios (Figure 1) were defined in order to achieve the financial equilibrium where the MSW management system covers the collection fee and starts generating profits. In fact, it is worth mentioning that those scenarios also assume that there are no major disruptions to waste collection or disposal due to unforeseen events, such as natural disasters [43,44] or pandemics [45]. In reality, such events can have a significant impact on waste management systems and could potentially affect the accuracy of the scenario’s projections [46].

Given these assumptions and restrictions, it is important to keep in mind that these scenarios remain eventual projections of the future of waste management in Algeria. It should not be taken as a definitive or static representation of what will happen, but rather as a starting point for discussion and analysis of potential policy and infrastructure changes that could lead to improvements in waste management practices and outcomes in Algeria. The four scenarios are shown below.

2.1.1. Scenario 1

This scenario (Figure 2), represents the baseline, reflecting the current state of waste management in 2022, where 51% of waste is sent to landfill without energy recovery, 41% is openly dumped, 1% is composted, and 7% is recycled. To ensure the scenario’s representativeness to the study area, we considered the collection type, with 50% of waste collected through bins and the rest through polyethylene single-use plastic sacks. The energy recovery from CH₄ emissions for this scenario is 0%. In 2020, landfill methane accounted for 60% of GHG emissions, with an additional 30% attributed to waste open burning [3,47].

2.1.2. Scenario 2

Overall, this scenario (Figure 3) aims to gradually improve the MSW system by reducing the amount of waste sent to open dumping to 28% and maintaining sanitary landfills to 43% with 20% energy recovery. It also aims to increase recovery rates by composting 15% and recycling 15% of the waste. To achieve this, source segregation at home is essential to ensure good-quality compost and efficient materials recovery.

2.1.3. Scenario 3

The third scenario (Figure 4) reflects the state’s objective to eradicate open dumping (20%), which is a major environmental and health hazard and a key goal of the PROGDEM program. The scenario proposes to reinforce the composting and recycling capacity in the country. This means that a greater proportion of the waste, specifically 25%, will be diverted away from landfills toward composting, while 25% will go to recycling facilities. The scenario also proposes to decrease the amount of waste that is landfilled (30%) with integrating 20% energy recovery. This means that waste that cannot be composted or recycled will be sent to landfills that have the capacity to recover energy from the waste. By doing so, the scenario aims to minimize the environmental impact of waste disposal while also generating energy.

2.1.4. Scenario 4

The fourth scenario (Figure 5) is the one where the financial equilibrium is met. According to this scenario, 50% of the MSW is composted, 15% is landfilled with 20% energy recovery, 25% is recycled, and only 10% is open dumped.

3. Results and Discussions

3.1. Global Environmental Impact Assessment

In terms of the global impact of the waste management system, Figure 6 shows that scenario 1, modelling the current waste management system, scores the worst for all impact categories. This confirms the higher impacts of the current waste management system based on low recycling and composting levels and high landfilling of valuable materials without any energy recovery and the release of landfilling methane to the atmosphere.

From scenario 2 to 4, we assist to a significant reduction of all the impact categories compared to scenario 1. For instance, transitioning from scenario 1 to scenario 2 results in an 84% reduction in climate change impact, primarily due to methane capture from landfills with 20% energy recovery. The US EPA [48] highlights that food waste in landfills decays quickly, contributing significantly to methane emissions, which constitute a large portion of overall landfill emissions. Consequently, capturing methane from landfills has been identified as a key strategy to reduce greenhouse gas emissions. Ngnikam et al. [49] also evaluated this potential, suggesting that introducing centralized composting or biogas plants before landfilling can further reduce greenhouse gas emissions from MSW.

Both scenarios 1 and 2 score positively in terms of climate change, whilst scenarios 3 and 4 are characterized by close negative balances of −2582 and −3018 Euro. Pers-Eq. In terms of acidification, all the scenarios present negative balances; however, scenario 2 shows a balance that is 10-folds lower than that of scenario 1, and scenarios 3 and 4 perform slightly better than scenario 2 and are quite equal with a value of −35,000 Euro. Pers-Eq. The impact in terms of eutrophication reveals that scenarios 1, 2, and 3 are particularly characterized with a positive balance; the trend is reversed only with scenario 4. Besides, the fresh water and human toxicities due to the four scenarios, as well as the depletion of the abiotic resources, are affected of a negative sign, yet scenario 3 shows the most performant configuration with regard to these three aspects, as indicated in Figure 6.

The differences in terms of energy recovery, recycling rate, and composting become more evident. In scenario 3, environmental neutrality is achieved through a well-balanced approach. Firstly, composting 25% of MSW significantly reduces the amount of waste sent to landfills and helps mitigate greenhouse gas emissions by diverting organic waste from anaerobic decomposition, which produces methane. Various studies support this approach; Yoshida et al. [50] conducted a greenhouse gas emission analysis for organic waste management in Madison, Wisconsin, using a Life Cycle Assessment approach; Zhu-Barker et al. [51] monitored greenhouse gas emissions from green waste compost windrows in California, estimating statewide total emissions; Pace et al. [52] developed a model to assess the impact of anaerobic digestion followed by composting on energy production, global warming potential, and water use. In addition, Nordhal et al. [53] reviewed the effects of waste characteristics, pretreatment processes, and composting conditions on greenhouse gas and air pollutant emissions, highlighting the potential for reduced emissions when waste is anaerobically digested before composting. Recycling 25% of MSW significantly reduces environmental impact by transforming materials such as paper, plastic, glass, and metal into new products. This process conserves natural resources, saves energy, and reduces pollution by decreasing the demand for virgin raw materials and diverting waste from landfills. For instance, the European Union has set targets for the reuse and recycling of waste materials, aiming for a minimum of 50% by weight for materials such as paper, metal, plastic, and glass from households by 2020 [54]. Lee and Tongarlak [55] investigated how converting retail food waste into by-products can mitigate waste in a retail setting. They compared mechanisms like waste disposal fees and tax credits for food donation and derived optimal order policies for retailers. The environmental implications of reuse and recycling of packaging have also been highlighted, emphasizing the challenges facing environmentally conscious manufacturing [56]. The remaining 50% MSW can be managed efficiently through landfilling with methane recovery. This method involves controlled waste disposal to capture methane gas produced during organic waste decomposition. Converting methane into energy prevents its release as a potent greenhouse gas. Effective landfill management, including methane capture and flaring, minimizes environmental impact. Studies show deploying methane capture lowers CO₂-equivalent emissions from waste sites [57,58]. Early gas recovery and reducing biodegradable waste in landfills are effective global measures for methane mitigation [59]. Landfill gas-to-energy projects not only offset emissions but also use methane beneficially. Further emission reductions may be challenging due to high costs in avoiding fugitive emissions. Nonetheless, methane capture is crucial for sustainable waste management, promoting responsible disposal practices and reducing environmental impacts [58].

Moreover, by combining composting, recycling, and appropriate landfill practices with methane recovery, scenario 3 achieves environmental neutrality. Early recovery of gas, and recycling and reducing biodegradable organic waste in landfills, are globally recognized as highly effective measures for mitigating methane emissions [59]. We suggest in the following section to analyse the implication of each stage in the waste management system in the simulated impact.

3.2. Contribution of Single Stages of Waste Management in Algeria

Figure 7a–e reports the results of simulations in terms of the LCIA of the single stages involved in the waste management process in Algeria, namely collection (a), transportation (b), treatment and recovery (c), landfilling (d), and recycling (e). It should be noted that a negative value means an environmental benefit/credit, whereas a positive value indicates an environmental burden.

Regarding the collection of MSW, scenario 1 (current practice) exhibits a significantly higher environmental impact compared to the other scenarios across all presented impact categories. This is due to the use of single-use plastic bags made of polyethylene to collect 50% of the MSW in scenario 1, as indicated in Figure 1, leading to a considerable impact on resource depletion and global warming potential. Despite the known negative environmental impact, employing single-use plastic bags for household waste is a widespread practice in many regions [60], including Algeria, where it is the most common way of packaging household items. However, it is worth noting that although a law was introduced in 2019 to prohibit the production and importation of black plastic bags [24], it has not been fully enforced yet. Consequently, the use of these bags for MSW collection and other purposes remains prevalent, thereby limiting the effectiveness of the law in reducing the environmental impact of single-use plastic bags.

The current practice of transporting MSW, corresponding to scenario 1, is found to have a lower environmental impact compared to other analyzed scenarios, across all the impact categories studied. For instance, scenario 1 scored 59% to 77% of the values recorded with scenario 2. This is primarily because scenario 1 requires fewer collection trucks for transporting MSW to the disposal site. In contrast, the other scenarios, which involve the separate collection of different waste fractions from cities to recycling facilities, require additional trucks, resulting in higher emissions and energy consumption, with an order of magnitude of at least 66.8 Euros. Pers-Eq in terms of climate change, 0.34 Euros. Pers-Eq. in terms of acidification potential, 2.9 and 19.6 Euros. Pers-Eq. for both freshwater and human toxicities, respectively, and finally, 0.6 Euros. Pers-Eq. for the depletion of abiotic resources, as shown in Figure 7b. All scenarios resulted in similar scores for eutrophication potential. Notably, the analysis did not include waste collection path optimization, which could further decrease greenhouse gas emissions. Researchers have explored route optimization using ant colony algorithms and Monte Carlo simulations, achieving up to 58% reductions in CO₂ emissions [61]. Waste compaction facilities can also cut GHG emissions by up to 40% by reducing the number of transport trucks required [62]. Life cycle assessment (LCA) approaches have evaluated MSW transportation’s environmental impacts, considering factors beyond global warming potential [61,63].

The stage of treatment and recovery is associated with an environmental impact shown in Figure 7c. In this stage of waste management, all the scenarios are affected of positive values, denoting a harmful effect on the environment. It is observed that scenario 1 has a lower environmental impact compared to the other studied scenarios, across all the analyzed impact categories, with a percentage ranging from 80% to 99%, increasing from scenario 2 to scenario 4, as compared to scenario 1. This is primarily because scenario 1 requires fewer facilities for waste recycling and composting, resulting in lower energy consumption and emissions. In contrast, the other scenarios involve the use of more recycling facilities and a larger composting factory, which increases energy consumption and the impacts associated with resource depletion and global warming potential.

Figure 7d reports the simulated values related to the environmental impact of the landfilling stage in the WM system. The most harmful impact is recorded with scenario 1 within all the impact categories, except the depletion of abiotic resources. It is particularly significant in terms of climate change and the eutrophication potential, with relative contribution to the global impact of 80%. The landfilling is the main contributor to CH₄ emissions in the waste sector [47,64]. Poorly managed landfill sites in which gas extraction systems are not utilized or where waste is simply dumped into an excavated hole are omnipresent in developing countries [8]. In this study, a 15% increase of the landfilling capacity without gas recovery or flaring for the PROGDEM scenario has caused an apparent rise of methane production. The installation of a flaring system reduces the methane emission by about 46%. The recovery of the biogas is a desirable solution with an excellent benefit for GHG reduction; statistics have shown that Europe takes the lead in biogas production, accounting for more than 50% of the industry’s share, followed by Asia with 32% and the Americas with 14% [65]. However, due to the low cost of fossil gas production in Algeria at the moment, this solution seems to face challenges. Nonetheless, biogas can still be directly combusted for on-site heat and energy provision using a decentralized approach, which involves utilizing combustion in Combined Heat and power Plants (CHP) [66]. It is noteworthy that at the end of the year 2020, the National Waste Agency (AND) identified a total of 220 landfilling and controlled discharges. Among the operational installations, there were 101 Class 2 landfilling sites. Class 2 landfilling sites are facilities designed for waste disposal, but they have certain control and monitoring features to reduce their impact on the environment. Furthermore, out of the 101 Class 2 landfilling sites, 22 were equipped with sorting equipment. Among these 22 landfilling sites with sorting equipment, 11 were operational.

From a life cycle assessment (LCA) perspective, recycling stage, whose simulated values of environmental impact are reported in Figure 7e, can help avoid the consumption of raw materials in the production process by reducing their extraction, reducing energy use and related wastes, and extending product life cycle. Thus, scenario 1 scores the worst among the four studied scenarios and presents the less promising benefit toward the environment in this axis. The emissions of greenhouse gases (GHGs) resulting from the primary production of metals derived from extracted raw material feedstocks have been extensively examined and are now thoroughly understood [67,68]. These emissions are widely recognized as substantial contributors to global GHG emissions.

3.3. Quantitative Contribution of MSW Composition Change in LCA Results

The influence of assumptions regarding household waste composition in waste management Life Cycle Assessments (LCAs) is primarily discussed in the studies conducted by Bisinella et al. [15] and Slagstadet al. [16]. This influence becomes particularly relevant in our study, where the waste composition is undergoing a notable transition characterized by a decrease in organic matter, an increase in plastic content, and a higher proportion of paper-cardboard.

In terms of global warming potential, Figure 8a shows that from 2000 to 2018, the GWP values decreased over time. Specifically, the GWP in 2000 was estimated at 6.98 $\times$ 10⁸ kg CO₂-Eq, and it decreased to 5.90 $\times$ 10⁸ kg CO₂-Eq by 2018. This suggests that over time, even with no change in waste management system, the waste composition is responsible for emitting fewer greenhouse gases. Overall, the amount of decrease in global warming potential from 2000 to 2018 is approximately 15.46%.

The analysis of the results related to the eutrophication potential Figure 8b indicates that from 2000 to 2018, the eutrophication potential values decreased slightly over time. Specifically, the eutrophication potential in 2000 was estimated at 5.20 × 10⁵ kg PO4-Eq, and it decreased to 3.76 × 10⁵ kg PO4-Eq by 2018. This indicates that MSW management systems have been releasing fewer nutrients, such as phosphorus, into aquatic ecosystems that can lead to excessive plant and algae growth, which can harm aquatic life.

Figure 8c also reveals that in terms of human toxicity, the estimation of HTP infinite from 2000 to 2018 exhibits a slightly decreasing trend over time. The human toxicity was estimated in 2000 at 15.3 × 10⁵ kg 1,4-DCB-Eq, and it decreased to 12 × 10⁵ kg 1,4-DCB-Eq in 2018.

This findings align with those of Slagstad and Brattebø [16], indicating that a shift of approximately 10% in major waste fractions (organic matter, paper, and plastic) in Algerian waste composition leads to over a 10% change in global warming potential, eutrophication potential, and human toxicity impacts. This trend is significant as it suggests a decrease in compostable waste and an increase in recyclable materials, potentially challenging national strategy objectives. Additionally, discrepancies in results can arise from the choice of LCA model and software, despite using identical initial data and assumptions [54]. Despite these challenges, LCA remains crucial for pinpointing environmental concerns and proposing context-specific enhancements [69]. To bolster the reliability of waste management LCAs, researchers should aim to standardize non-geographical assumptions, validate models, and transparently disclose methodological assumptions [28,69].

3.4. Strategic Implications and Critical Analysis of Algeria’s National Waste Management Strategy 2035

In the present section, the footprint related to the National Waste Management Strategy 2035 is assessed, and the technical feasibility is critically analyzed in order to objectively evaluate the orientations of Algeria in terms of waste management and the alternatives for a viable strategy, in accordance with the sustainable development goals stated by the United Nations [70], particularly SDG 11.6 and 12.

Scenario 2 serves as the launching point as it introduces significant changes and improvements to the MSW system. It aims to reduce open dumping, increase energy recovery in sanitary landfills, and promote composting and recycling. This scenario emphasizes the importance of source segregation, education, incentives, and infrastructure investment to achieve sustainable waste management practices. By implementing these measures, it can bring about transformative changes in waste management and contribute to the overall well-being of the country and its citizens. To successfully implement Scenario 2 and achieve its objectives, strategic planning and actions must be taken in several key areas.

According to the National Strategy 2035, the primary objectives are to eliminate open dumping, enhance landfilling with energy recovery, promote composting of compostable waste, and strengthen recycling efforts. Figure 9 reports the evolution of the quantities of landfilled, composted, recycled, and openly dumped waste as well as the energy recovery corresponding to the four scenarios. There is a noticeable decrease in the quantity of waste being sent to landfills as we progress from scenario 1 to 4. This reduction in landfilling is attributed to a significant increase in the quantities of materials being composted and recycled. This trend is clearly illustrated by showcasing the corresponding rise in both composted and recycled materials alongside the decrease in landfilled waste. In order to achieve the target, it is crucial to invest in the necessary infrastructure for waste collection, sorting, composting, recycling, and energy recovery facilities. This requires establishing composting plants, transfer stations, and recycling centers, as well as upgrading existing sanitary landfills to incorporate energy recovery technologies.

The drive for energy independence serves as a primary motivator for advancing and accepting alternative energy sources. Currently, Algeria heavily relies on its fossil fuel reserves as part of its energy strategy, while its untapped renewable energy potential leads to a relatively modest contribution of renewables to power generation capacity and electricity consumption. The existing infrastructure and expertise are predominantly oriented toward fossil fuel extraction. However, recognizing the need for diversification, Algeria has enacted a Renewable Energy and Energy Efficiency Development Plan for 2030, emphasizing the installation of solar and wind systems [71]. With a strong commitment to achieving their recently established renewable energy targets, the Algerian government is making significant investments in solar power. Given its close proximity to Europe and the aim of reaching 40% renewable energy generation by 2030, around 60 renewable energy projects are scheduled to be executed during this period [72]. While biogas production offers environmental benefits, it is currently more expensive than fossil fuel-based methane production due to additional infrastructure and processes. However, with future considerations, the country may re-evaluate its approach to align with sustainability goals and advancements in technology. In 2012, an experimental simulation performed in Algeria demonstrated successful biogas production results, enabling the recovery of approximately 250 MWh/year of electricity and around 354 MWh/year of thermal energy [73]. Additionally, the National Institute of Agronomic Research of Algeria (INRAA) and the Renewable Energy Development Center (CDER) implemented two successful experimental plants in Bechar and Ben Aknoun to study biogas production from cow dung, as reported by Boukelia and Mecibah [74]. At the national level, the government has undertaken significant efforts since in the PROGDEM program for biogas recovery and flaring. Notable examples include the implementation of a biogas recovery and flaring system with a capacity of 5000 Nm³/h at The OuedSmar landfill in the capital Algiers, 3000 Nm³/h at the Ouled Fayet landfill also in Algiers, and 500 Nm³/h at the Berka Zarga landfill in Annaba, Zef Zef landfill in Skikda, and Boulimat landfill in Béjaia. Flaring methane (CH₄) is considered less impactful than its direct release into the air; however, inadequate landfill management in some cases may still result in the release of CH₄ into the atmosphere.

Transforming landfill gas LFG into energy is a crucial part of this study to achieve GHG neutrality in scenario 3 and 4. However, it is imperative to note that the national strategy does not currently account for Waste-to-Energy (WtE) technologies. It is noteworthy to mention that leachate generation, collection, and treatment, as well as the recovery of LFGs from landfill sites, are still not experienced at most Algerian cities. Harnessing LFGs can assist in moving the waste management pyramid, producing renewable energy, and lowering emissions of GHGs. Due to poor landfill management, landfills become the third largest contributor to anthropogenic CH₄. As a result, specific actions are required to limit landfill CH₄ emissions. In addition, considering the significant population growth and stark population density disparity between the north and south of the country, the current reliance on landfilling appears to be increasingly detrimental to essential agricultural lands. The approach prevailing in landfilling is consuming fertile lands that are crucial for agriculture. Moreover, socially speaking, we assist to a resistance from the rural population as a manifestation of the so-called “Not In My Backyard” phenomenon (NIMBY) [75,76] toward the installation of new landfilling sites.

The strategic-driven change requires an adequate Policy and Regulatory Framework as well, by developing and enforcing waste management policies and regulations that promote waste reduction, source segregation, composting, recycling, and energy recovery. This includes setting targets, establishing standards, and ensuring compliance. By investing in energy recovery, for example, landfills can not only secure their energy bills and contribute to long-term environmental sustainability but can also actively participate in the energy transition. However, this can only be possible if the necessary regulatory framework enables the injection of heat or electricity into the electricity grid or a heat network.

The “Ladder of Lansink” principle, introduced by Dutch politician Ad Lansink in 1979 [77], has evolved to form the foundation for the internationally recognized Waste Hierarchy or Hierarchy of Waste Management schematized in the supplementary information Figure S3a, which became a crucial component of waste legislation at the European Union (EU) and global levels [78]. It outlines a structured approach to waste management and resource conservation, emphasizing the importance of reducing waste generation and prioritizing more sustainable alternatives to landfilling.

As a simple schematic illustration, the Ladder of Lansink clarified an order of preference for waste management and resource conservation options, with “reduce/reuse” at the top and “landfill” at the bottom. Waste policies and targets at the EU level include minimum requirements for managing certain waste types to meet the Waste Hierarchy requirements. For municipal waste, key targets include the Landfill Directive [79,80,81], the Packaging and Packaging Waste Directive’s [82], recycling targets, and the Waste Framework Directive’s [83] and targets on recycling and preparing for reuse [84]. This last directive represents a significant milestone in modern waste management within the EU. It introduces restrictions on landfilling from 2030 for all waste that is suitable for recycling or other material or energy recovery. Additionally, it establishes a general requirement for Extended Producer Responsibility (EPR), stating in article 8 that “Member States may implement legislative or non-legislative measures to ensure that any natural or legal person involved in the development, manufacture, processing, treatment, sale, or importation of products (producers) assumes extended producer responsibility to strengthen waste re-use, prevention, recycling, and other recovery efforts” [84].

To comply with the Waste Hierarchy priorities, the Algerian government should gradually restrict organic waste landfilling (54% of MSW) and promote composting (Figure S3b). Additionally, Algeria should establish regulations to encourage recycling programs, such as implementing Extended Producer Responsibility regulations and setting recycling targets for various waste streams.

Economically speaking, the cost of MSW management is significantly affected by the chosen waste treatment method. In low-income countries, the collection represents 80–90% of the total MSW budget, because most of the waste is sent to open dumps. On opposed direction, collection represents 10% of the total MSW budget in high-income countries due to the higher costs associated with more sophisticated MSW management techniques, which include sanitary landfill and incineration.

In Algeria, the current MSW management system allows to cover only 2% of the total waste management budget, estimated to be 36.3 billion Algerian Dinars in 2017. The main causes of this deficiency are the low amount of recycling, the neglectable quantity of composting, and the poor waste collection charge recovery. Thus, according to the National Strategy 2035 [32], financial equilibrium in waste management can be achieved by changing the service fees from a flat rate of 2000 Algerian Dinars (DZD) per household per year to 1% of household income, with at least 41% cost recovery from citizens at the national level. Additionally, achieving this equilibrium requires that 50% of MSW be composted, 25% be recycled, and the remaining 25% be properly landfilled with effective energy recovery.

The success of these strategies appears to rely on population participation and positive behaviours in source segregation, which are unlikely to occur without additional incentive measures and policies. Currently, the legal framework for Extended Producer Responsibility, which is crucial for organizing recycling activities by waste fractions, does not exist in Algeria.The success of the National Waste Management Strategy relies on effective source segregation of waste. Improving recycling rates presents a significant challenge, particularly when it comes to addressing the psychological attitudes of the public [85]. However, by fostering a positive shift in residents’ behavior toward waste recycling, we can unlock greater value within the recycling practice. To achieve this, it is essential to launch public awareness campaigns that educate the population about the importance of waste management, source segregation, and the numerous benefits of composting and recycling. These campaigns should aim at promoting behavioral changes and provide guidance on proper waste disposal practices. These initiatives should emphasize the benefits of composting organic waste and recycling materials, highlighting the reduction of waste sent to landfills, conservation of natural resources, and prevention of pollution. To ensure the effectiveness of these campaigns, a diverse range of communication channels should be utilized, such as television, radio, social media, and community engagement. In this context, it is worth mentioning the important role played by the local branches of the National Conservatory of Environmental Training (CNFE) known as “Houses of the Environment.” As public institutions, these houses offer specialized programs tailored to the needs of various environmental stakeholders, including public administration officials, environmental management professionals, business leaders, and civil society actors. Moreover, these houses not only serve as training centers and information resources but also play an active role in organizing a wide array of activities such as events, conferences, exhibitions, and awareness campaigns. In addition, in order to maximize revenues and encourage positive recycling behavior, certain residents may be motivated to make changes, resulting in a more proactive approach to recycling household waste compared to their previous habits [85]. To promote effective waste management, it is essential to provide incentives and support to households and businesses actively participating in waste reduction, composting [86], and recycling efforts. This support can take various forms, including financial incentives, tax breaks, subsidies, and recognition programs. Finally, training waste management personnel, including collection workers, sorting facility staff, composting experts, and recycling operators, and providing technical assistance and knowledge transfer, can ensure efficient and effective operations and strengthen local expertise. Fostering collaboration among government agencies, private sector entities, non-governmental organizations, and communities would also leverage resources, share best practices, and promote innovation in waste management.

Therefore, and from environmental, technical, economic, and social perspectives, it is crucial to establish a flexible long-term strategy that considers future actions allowing the country to reassess its approach in alignment with sustainability goals and advancements in technology.

In terms of monitoring and evaluation, it is also necessary to establish a robust system to track progress, measure performance against set targets, and identify areas for improvement related to the Waste Management Strategy. This should include regularly reviewing and updating strategies based on feedback and obtained results.

To adequately address the trends identified in this study, it is finally essential for the strategy to incorporate a projected waste composition based on Prospective Life Cycle Assessment. By considering the study’s findings, the national strategy can better anticipate and adapt to the changing waste composition, enabling the implementation of effective waste management practices over time.

3.5. Limitations, Outlook and Recommendations

In this study, we encountered several limitations concerning Sensitivity Analysis, Time Series Forecasting, Data Quality and Availability, and Economic Analysis. Addressing these limitations in future research will significantly enhance the robustness and applicability of the findings. Future studies can provide more reliable and actionable insights for sustainable waste management in Algeria.

4. Conclusions

This article provides precise and relevant data on the environmental impact of waste management in Algeria and nations with similar municipal waste characteristics and municipal waste management orientations, through Life Cycle Impact Assessment (LCIA) using the WRATE tool and Ecoinvent database version 2.

The study offers several key contributions:

(i)

It conducts a comprehensive analysis of the environmental impacts associated with various waste management scenarios in Algeria, highlighting the benefits of transitioning from current practices to more sustainable options. The research underscores the significant environmental gains achievable through strategic policy interventions.

(ii)

A scenario-based impact assessment reveals that the baseline scenario (scenario 1) describes the highest negative environmental impact.

(iii)

Scenario 2, incorporating methane capture from landfills with 20% energy recovery, demonstrates an 84% reduction in climate change impact, illustrating the potential of advanced waste management technologies to mitigate environmental harm.

(iv)

Stage-specific insights emphasize landfilling of MSW as the predominant contributor to adverse environmental impacts across all scenarios, particularly pronounced in scenario 1. In contrast, due to the limited number of trucks, current transportation practices show comparatively lower environmental impacts. However, future scenarios are anticipated to involve increased truck traffic, necessitating optimization algorithms for routing. This proactive approach is essential to maximize efficiency and minimize environmental impacts achieving up to 58% reductions in CO₂ emissions.

(v)

The study proposes financial equilibrium achieved by changing the service fees from a flat rate of 2000 Algerian Dinars (DZD) per household per year to 1% of household income, with at least 41% cost recovery from citizens at the national level, with minimum recovery targets for composting (50%), recycling (25%), and efficient landfilling (15%) with 20% energy recovery.

(vi)

Critical findings underscore the urgency of transitioning from conventional waste management practices toward Scenario 2 and beyond, where methane capture and increased recycling significantly improve environmental outcomes.

(vii)

The shift in waste composition toward reduced organic content and increased recyclables presents both challenges and strategic opportunities for future policy development in Algeria and nations with similar municipal waste characteristics and strategic municipal waste management orientations.

(viii)

Policy implications include the need for strengthened infrastructure and review of the legislative frameworks to manage methane emissions efficiency. Promoting composting and recycling initiatives, along with implementing strict regulatory measures such as extended producer responsibility, emerge as key strategies. Addressing financial sustainability in waste management requires innovative tax reforms and increased recovery rates to achieve fiscal equilibrium while advancing environmental objectives.