LCA as a tool in SEA of municipal solid waste management in Vietnam

Life cycle assessment (LCA) is considered as an effective tool in strategic environmental assessment (SEA), which used to manage of municipal solid waste in Vietnam. The process integrated decision-support tools for scenario planning, public participation and environmental assessment. This research describes the use of LCA for environmental assessment in solid waste management, with focus on methodology and practical experiences in Vietnam. The results were indicated that based on the characteristics of solid wastes, and availability of disposal options, LCA supports the identification of opportunities for pollution prevention and reductions in resource consumption while taking the entire municipal solid waste life cycle. The primary elements of solid waste management are generation, collection, transportation, treatment, and disposal. Different scenarios were developed and reported as alternatives to the current waste management systems. The most significant environmental savings in Vietnam is material recovery facility (MRF) and energy recovery.

Keywords: life cycle assessment (LCA), municipal solid waste, Vietnam

The generation of solid waste is an inherent outcome of human existence. These wastes encompass materials discarded from human and animal activities, typically in solid form, considered useless or unwanted. Managing solid waste is a multifaceted environmental challenge that demands consideration from technical, economic, environmental, and social perspectives, with a focus on sustainability. To maintain a healthy environment, both municipal and industrial wastes should adhere to the solid waste management hierarchy, which includes prevention, minimization, recovery, incineration, and landfilling [1]. Various techniques can be employed to achieve this objective. One such technique is Environmental Life Cycle Assessment (LCA), a comprehensive analytical tool introduced in the 1960s to assess the raw material and energy limitations in the USA [2]. Initially concentrating on energy and resource requirements of waste, LCA examines environmental aspects and potential impacts throughout a product's life cycle, from raw material acquisition to production, use, and disposal, encompassing the period from when an item becomes valueless and is discarded to when its value is restored by transforming it into usable material or energy. Up until this point, much like other developing nations, Vietnam has faced a shortage of databases and calculation methodologies for evaluating the environmental effects of different waste treatment approaches. This research specifically concentrated on gauging the effects of alternative waste treatment options, encompassing factors such as greenhouse gas (GHG) potential, mitigation measures, energy content, landfill volume reduction, and diverse benefits. The aim was to propose suitable choices through scenario analyses tailored to representative cities in Vietnam [3].

This is especially true for plans that have the potential to impact activities extending well beyond the immediate technical and geographical confines of the plan itself. This situation is notably applicable to municipal waste plans. The comprehensive systems perspective inherent in life cycle assessment (LCA) (ISO, 2006a,b), which spans from the production stage to disposal, considering both direct and indirect effects, proves valuable in the environmental assessment of Strategic Environmental Assessment (SEA). This helps prevent sub-optimization. Another illustration is provided by Salhofer et al. (2007), who detail the application of LCA in the SEA of a regional waste management plan in Austria [4]. This article presents the application of LCA in SEA of municipal solid waste planning. This process incorporates various planning tools, such as LCA, scenario planning, and participative tools. The primary objective of this approach is to enhance the legitimacy and effectiveness of municipal solid waste, particularly in steering local municipal solid waste systems toward reduced environmental impact. One key aspect involves integrating LCA to provide a broader systems perspective for environmental assessment.

Methology

To assess the viability of relevant municipal solid waste treatment options in Vietnam, a scenario analysis employing LCA method was conducted. The LCA models encompass all processes, materials, energy usage, and emissions within their defined system boundaries. To evaluate the impact of alternative waste treatment practices on greenhouse gas (GHG) emissions reduction, energy consumption and generation, landfill volume reduction, and other benefits guiding appropriate selection, a scenario analysis based on these alternative practices was executed. The scenarios were classified based on applicable waste treatment alternatives for Vietnamese cities. This study concentrated on seven scenarios: the baseline scenario, open dumping scenario (S0), sanitary landfill without landfill gas (LFG) recovery scenario (S1), sanitary landfill with LFG recovery scenario (S2), composting scenario (S3), incineration with energy recovery scenario (S4), and a scenario combining composting and incineration with energy recovery (S5).

Results and discussion

Greenhouse Gas Emission and Mitigation

Table 1 illustrates the greenhouse gas (GHG) emissions, measured in concentration of CO ₂ equivalent, for each alternative scenario. The assessment focused on GHG emission mitigation through energy generation. The findings indicated that scenario S4 represented the most effective practice in terms of GHG emission reduction, followed by scenarios S2, S3, S5, S0, and S1. Some scenarios displayed negative GHG emission values, indicating their contribution to GHG mitigation. A significant portion of the total GHG emissions from treatment alternatives was attributed to direct GHG emissions from waste. Nonetheless, the GHG emissions from energy and other facilities also constituted a substantial percentage of the overall GHG emissions, particularly evident in scenarios S4, S5, and S2.

Table 1

Landfill Volume Reduction and products from waste treatment alternatives Analysis

They are summarized in Table 1. The findings reveal that scenarios S3, S4, and S5 successfully reduced the volume of residual waste deposited in final disposal sites. Both the composting scenario and incineration scenarios exhibited minimal discharge of residual waste to landfills. Incineration, in particular, demonstrated an exceptional volume reduction, exceeding 85 %, while the composting scenario achieved a reduction within the range of 52–79 %. Table 1 also outlines the productions resulting from waste treatment alternatives. Composting products, derived from organic waste recycling, were observed in scenarios S3 and S5. Power generation, stemming from the energy recovery option, was generated in scenarios S2, S4, and S5. Scenario S4 emerged as the most efficient power generation practice, followed by scenarios S2 and S5.

The positive impacts and benefits of compost products applied in soil have been assessed by various authors. Hargreaves et al. (2008) highlighted the potential of organic waste composting as a beneficial recycling tool for waste management, reducing landfill-bound waste volume and providing safe fertilizer for agricultural fields. Energy generation, measured in kilowatt-hours, includes both excess energy exported to the national grid and energy recovered according to demand. This has implications for energy consumption (natural resources) and greenhouse gas (GHG) emissions (pollution) from energy consumption and fuel manufacturing processes.

Conclusion

LCA proves effective in this setting and enhances best practices by offering a comprehensive systems perspective and a systematic framework. However, it is acknowledged that while LCA surpasses the explicit requirements for environmental assessment in SEA, it falls short in addressing all necessary aspects. Therefore, a complementary use of other tools is essential. Despite encountering methodological challenges when integrating LCA with participative tools and scenario planning, this approach proved innovative in shaping the scope of environmental assessment and in defining and evaluating alternatives.

References:

1. A. M. Ferrari, L.Volpi, D. Settembre-Blundo, F. E. García-Muina Dynamic life cycle assessment (LCA) integrating life cycle inventory (LCI) and Enterprise resource planning (ERP) in an industry 4.0 environment. — Journal of Cleaner Production, 2021.

2. Tukker A. Life cycle assessment as a tool in environmental impact assessment. — Environ Impact Assess, 2000.

3. Thanh, N g uyen & MATSUI, Yasuhiro. Scenario Analyses on Municipal Solid Waste Treatment Alternatives in Vietnam by using Life-cycle Approach . — Conference: 7th Asian Pacific Landfill Symposium (APLAS): Sustainable Solid Waste Management for a Better Life,2012

4. Salhofer, S., Wassermann, G., & Binner, E. Strategic environmental assessment as an approach to assess waste management systems. Experiences from an Austrian case study. — Environmental Modelling Software,2007.