Assessment of environmental sustainability of solid waste management system of Dhaka city through life cycle analysis – Nature

Report on Sustainable Solid Waste Management Strategies for Dhaka City

Executive Summary

This report presents a life cycle analysis (LCA) of municipal solid waste management (MSWM) in Dhaka, Bangladesh, evaluating current practices against feasible alternatives to identify a strategy aligned with the Sustainable Development Goals (SDGs). Dhaka’s reliance on landfilling poses significant threats to public health and the environment, undermining progress towards SDG 3 (Good Health and Well-being), SDG 11 (Sustainable Cities and Communities), and SDG 12 (Responsible Consumption and Production). The analysis compared the baseline landfilling scenario (B0) with four alternative strategies (A1-A4) incorporating composting and incineration. The findings indicate that Scenario A2, which combines approximately 75% composting with 8.8% incineration, is the most environmentally sustainable option. This strategy demonstrates the greatest potential for reducing negative impacts on water and ecosystems, directly supporting SDG 6 (Clean Water and Sanitation), SDG 14 (Life Below Water), and SDG 15 (Life on Land). Composting emerged as the most viable long-term solution for land use, a critical factor for achieving SDG 11.6 (reduce the environmental impact of cities). Conversely, strategies heavily reliant on incineration show limited contribution to SDG 7 (Affordable and Clean Energy) and present trade-offs concerning SDG 13 (Climate Action) and human health. This report recommends adopting an integrated approach centered on composting to advance Dhaka’s sustainable development agenda.

1.0 Introduction: Aligning Waste Management with Sustainable Development Goals

Dhaka, the capital of Bangladesh, generates approximately 6,465 tons of waste daily. The current management system, which disposes of roughly 4,700 tons per day in exhausted landfills, presents a significant challenge to sustainable urban development. This practice directly conflicts with several SDGs:

• SDG 11 (Sustainable Cities and Communities): Uncontrolled dumping degrades urban environments, and the scarcity of land makes landfill expansion an unsustainable solution.
• SDG 3 (Good Health and Well-being): Leachate contamination and emissions from landfills pose severe risks to public health, including respiratory diseases and cancer among waste workers and nearby populations.
• SDG 6 (Clean Water and Sanitation): Leachate from unlined landfills contaminates surrounding water bodies, threatening the city’s water security.
• SDG 12 (Responsible Consumption and Production): The current linear model of waste disposal fails to capture the value of waste as a resource, hindering the transition to a circular economy.

Recognizing these challenges, this study utilizes a Life Cycle Analysis (LCA) to evaluate alternative MSWM strategies, providing a scientific basis for decision-making that aligns with Dhaka’s commitment to the 2030 Agenda for Sustainable Development.

2.0 Methodology for Sustainable Assessment

2.1 Goal and Scope

The objective was to assess the environmental sustainability of different MSWM strategies for Dhaka city, focusing on their potential to contribute to the SDGs. The LCA covered a “gate-to-grave” system boundary, from waste collection at Secondary Transfer Stations (STSs) to final disposal or treatment. The functional unit for the analysis was 1,904,249 tons of annually collected municipal solid waste.

2.2 Scenarios Evaluated

Five scenarios were modeled to compare environmental impacts:

1. B0 (Baseline): Current practice of landfilling.
2. A1 (Landfilling + Composting): A strategy prioritizing composting for organic waste.
3. A2 (Landfilling + Composting + Incineration): A mixed strategy with a high emphasis on composting (75%) and supplementary incineration (8.8%).
4. A3 (Landfilling + Composting + Incineration): A mixed strategy with a more balanced share between composting and incineration.
5. A4 (Landfill + Incineration): A strategy focused primarily on incineration.

2.3 Life Cycle Impact Assessment (LCIA)

The analysis was conducted using openLCA software with the ecoinvent 3.8 database. The ReCiPe2016 method was employed to assess impacts across multiple midpoint and endpoint categories, which were then mapped to relevant SDGs.

• Midpoint Categories: Included global warming (SDG 13), land use (SDG 11, SDG 15), water consumption (SDG 6), freshwater and marine eutrophication (SDG 6, SDG 14), and human toxicity (SDG 3).
• Endpoint Categories: Assessed the ultimate damage to human health (DALYs) and ecosystems (species.yr), providing a holistic view of impacts on SDG 3, SDG 14, and SDG 15.

3.0 Results and Discussion: SDG Impact Analysis

3.1 Midpoint Impact Analysis

The LCIA revealed that no single strategy was optimal across all categories, but clear trends emerged in relation to key SDGs.

• Scenario A2 (High Composting, Low Incineration) was identified as the most environmentally favorable strategy. It offered the best performance in categories directly impacting ecosystem health, including:
  • Fine particulate matter formation (relevant to SDG 3 and SDG 11)
  • Freshwater and marine eutrophication (SDG 6 and SDG 14)
  • Marine ecotoxicity (SDG 14)
• Scenario A1 (Composting and Landfilling) was the second-best option, showing the most significant reduction in freshwater ecotoxicity, human carcinogenic toxicity, and terrestrial ecotoxicity. This highlights the strong contribution of composting to SDG 3, SDG 6, and SDG 15.
• Incineration-heavy Scenarios (A3, A4) performed best in reducing global warming potential by avoiding methane emissions from landfills, a positive contribution to SDG 13 (Climate Action). However, they were the worst performers for ozone formation, human carcinogenic toxicity, and stratospheric ozone depletion, presenting a direct conflict with SDG 3.
• Baseline Scenario (B0) was the most detrimental in nearly all toxicity and eutrophication categories, confirming its unsustainability and negative impact on multiple SDGs.

3.2 Land Use and Sustainable Cities (SDG 11 & SDG 15)

Land use is a critical constraint for Dhaka. While both composting and incineration reduce the land required compared to landfilling, their long-term sustainability differs.

• Composting: Requires approximately 78% less land than landfilling. The land can be reused continuously, making it a highly sustainable long-term solution that supports compact urban development (SDG 11.3) and reduces pressure on terrestrial ecosystems (SDG 15.1).
• Incineration: While reducing waste volume by 90%, it generates bottom ash that requires landfilling. Over a 10-year period, the cumulative land required for ash disposal would surpass that needed for a composting facility, making it a less sustainable option from a land-use perspective.

3.3 Energy Generation and Clean Energy (SDG 7)

The potential for waste-to-energy (WtE) to contribute to SDG 7 (Affordable and Clean Energy) was found to be minimal. Due to the high moisture content and low calorific value of Dhaka’s waste, even the most aggressive incineration scenario (A4) would generate only 3-5% of the city’s electricity demand. This suggests that WtE should not be the primary driver for adopting incineration technology in Dhaka.

3.4 Endpoint Analysis: Human Well-being (SDG 3) and Ecosystems (SDG 14, SDG 15)

The endpoint analysis confirmed the superiority of composting-focused strategies. Scenarios A1 and A2 resulted in a net reduction in disability-adjusted life years (DALYs) and a net saving of species per year, indicating positive impacts on human health and biodiversity. In contrast, the baseline (B0) and incineration-heavy (A4) scenarios resulted in increased DALYs and species loss, demonstrating their negative long-term consequences for achieving SDGs.

4.0 Conclusion and Recommendations for Sustainable Urban Development

The life cycle analysis provides clear evidence that an integrated waste management strategy centered on composting is the most effective path for Dhaka to align its MSWM system with the Sustainable Development Goals.

4.1 Key Findings

1. The A2 scenario (75% composting, 8.8% incineration) is the most preferable option, offering significant environmental savings and contributing positively to SDGs 3, 6, 11, 12, 14, and 15.
2. Composting is a cornerstone of sustainable waste management in Dhaka. It is the most feasible long-term solution for land use, creates a valuable product (compost) that supports sustainable agriculture (SDG 2), and significantly reduces pollution.
3. Incineration presents significant trade-offs. While beneficial for mitigating climate change (SDG 13), its negative impacts on human health (SDG 3), long-term land use, and minimal contribution to clean energy (SDG 7) make it a less desirable primary strategy.
4. The current landfill-based system (B0) is fundamentally unsustainable and actively undermines progress towards a healthy, resilient, and sustainable city.

4.2 Recommendations

To advance its sustainable development agenda, the city of Dhaka should:

• Prioritize the development of large-scale composting facilities to manage the city’s significant organic waste fraction, thereby advancing a circular economy in line with SDG 12.
• Adopt an integrated strategy resembling Scenario A2, using composting as the primary treatment method, supplemented by limited incineration for non-compostable, high-calorific-value waste.
• Invest in data collection and monitoring systems to improve the accuracy of future environmental assessments and track progress towards SDG targets related to waste management.
• Conduct a full life cycle cost analysis and environmental impact assessment (EIA) for any proposed waste management project to ensure economic feasibility and alignment with the environmental priorities identified in this report.

SDG Analysis of Dhaka’s Solid Waste Management

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The article on solid waste management in Dhaka city addresses several Sustainable Development Goals (SDGs) due to the interconnected nature of waste management with public health, environmental quality, and urban sustainability. The following SDGs are relevant:

• SDG 3: Good Health and Well-being: The article directly links improper waste management to public health risks. It states that waste poses a “serious threat to public health” and that waste workers’ “vulnerability to pathogen attack” is increased. It also mentions that “long-term continuous exposure to pollutants can cause cancer and chronic obstructive pulmonary diseases (COPD).”
• SDG 6: Clean Water and Sanitation: The study highlights the impact of waste on water bodies. It mentions that Dhaka is surrounded by rivers and discusses the “leachate produced from waste” at landfill sites. The life cycle analysis (LCA) assesses impacts like “freshwater eutrophication” and “marine eutrophication,” which are direct consequences of water pollution from waste.
• SDG 7: Affordable and Clean Energy: The article explores Waste-to-Energy (WtE) as a potential waste management strategy. It evaluates incineration scenarios for their potential to generate electricity, noting that the electricity generated could only meet “3–5% of the concurrent requirement,” thus connecting waste management to energy production.
• SDG 11: Sustainable Cities and Communities: This is a central theme of the article. The entire study is focused on finding a “sustainable waste management approach for Dhaka city,” a highly populated urban area. It deals with municipal solid waste management (MSWM), the capacity of landfills, and the overall environmental impact of the city’s waste.
• SDG 12: Responsible Consumption and Production: The article’s core is about the sustainable management of post-consumption waste. It analyzes various strategies, including landfilling, composting, incineration, and recycling, to promote a more resource-efficient society and reduce the environmental burden of waste.
• SDG 13: Climate Action: The analysis explicitly includes “global warming” as a key environmental impact category. It discusses how different waste treatment methods contribute to greenhouse gas emissions, noting that incineration “eliminates methane emissions from organic waste due to landfilling or composting processes,” thereby impacting climate change.
• SDG 14: Life Below Water: The impact on marine ecosystems is assessed through the “marine eutrophication” and “marine ecotoxicity” categories in the LCA. This connects land-based waste management practices in Dhaka to the health of downstream marine environments.
• SDG 15: Life on Land: The article addresses the impact of waste management on terrestrial ecosystems. It analyzes “land use” as a critical factor, comparing the land required for landfills, composting, and incineration. It also measures “terrestrial ecotoxicity” to evaluate the harm caused to land ecosystems.

2. What specific targets under those SDGs can be identified based on the article’s content?

Based on the issues discussed, the following specific SDG targets are identifiable:

1. Target 3.9: By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contamination.
   • Explanation: The article connects improper waste disposal with severe health risks, including “cancer and chronic obstructive pulmonary diseases (COPD)” and “pathogen attack” for waste workers. The analysis of “fine particulate matter formation” and “human carcinogenic toxicity” directly relates to measuring pollution that causes illness and death.
2. Target 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials.
   • Explanation: The study addresses water pollution from landfills through “leachate produced from waste.” The assessment of “freshwater eutrophication” and “marine eutrophication” quantifies the impact of nutrient pollution on water bodies, directly aligning with the goal of reducing water pollution.
3. Target 7.2: By 2030, increase substantially the share of renewable energy in the global energy mix.
   • Explanation: The article evaluates incineration as a Waste-to-Energy (WtE) technology. It quantifies the “total electricity produced in MWh/year” from different incineration scenarios, treating waste as a potential source for clean energy and thus contributing to the energy mix.
4. Target 11.6: By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management.
   • Explanation: This target is the primary focus of the article. The entire study is a life cycle analysis (LCA) aimed at finding “an answer for a sustainable waste management approach for Dhaka city” by comparing the environmental impacts of different Municipal Solid Waste Management (MSWM) strategies.
5. Target 12.5: By 2030, substantially reduce waste generation through prevention, reduction, recycling and reuse.
   • Explanation: The article evaluates alternatives to simple dumping, such as composting (which recycles organic nutrients) and recycling of materials like paper and plastic. It notes that “informally, waste pickers and scavengers… perform recycling,” and these processes are included in the LCA to assess their environmental benefits.
6. Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities.
   • Explanation: The LCA in the article measures “marine eutrophication” and “marine ecotoxicity,” directly assessing how Dhaka’s land-based waste management practices contribute to the pollution of marine ecosystems.
7. Target 15.1: By 2020, ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services.
   • Explanation: The article emphasizes the problem of “land use” for landfills in a land-scarce city like Dhaka. It quantifies the land area required for different waste management scenarios and assesses “terrestrial ecotoxicity,” linking waste management directly to the health and sustainable use of terrestrial ecosystems.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article mentions and implies several quantitative and qualitative indicators that can be used to measure progress:

• Waste Generation and Collection Rates (Indicator for Target 11.6): The article provides specific data points, such as the city producing “6,465 tons of waste daily” and a collection efficiency of “75–80%.” These figures directly correspond to indicator 11.6.1 (Proportion of municipal solid waste collected and managed in controlled facilities).
• Life Cycle Impact Assessment (LCIA) Categories (Indicators for multiple targets): The LCIA provides a suite of quantitative indicators to measure environmental impact. These include:
  • Global Warming Potential (kg CO2 eq.): An indicator for climate action (SDG 13).
  • Freshwater and Marine Eutrophication (kg N eq.): Indicators for water quality (SDG 6) and life below water (SDG 14).
  • Land Use (m²a crop eq.): An indicator for sustainable land use (SDG 15).
  • Fine Particulate Matter Formation and Human Carcinogenic/Non-carcinogenic Toxicity: Indicators for public health impacts (SDG 3).
  • Terrestrial Ecotoxicity: An indicator for impacts on life on land (SDG 15).
• Electricity Generation from Waste (Indicator for Target 7.2): The article quantifies the potential energy contribution, stating that incineration could generate “360,630; 466,908; and 573,330 MWh/year” under different scenarios. This represents “3.02%, 3.91%, and 4.79%” of Dhaka’s electricity consumption, serving as a direct measure for indicator 7.2.1 (Renewable energy share).
• Waste Composition and Recycling Potential (Indicator for Target 12.5): The article details the composition of Municipal Solid Waste (MSW), noting that organic waste is the major fraction (“86.29% and 84.94%”). It also identifies recyclable materials like paper, plastic, glass, and metal. This data is crucial for calculating recycling and composting rates, which are key metrics for target 12.5.
• Endpoint Health Indicators (Indicator for Target 3.9): The endpoint analysis uses “disability-adjusted life years (DALY)” to measure the overall impact on human health. The finding that some scenarios “reduced disability and increased life span” provides a high-level indicator of health outcomes from improved waste management.

4. Table of SDGs, Targets, and Indicators

Source: nature.com