Compost Quality and Markets Are Pivotal for Sustainability in Circular Food-Nutrient Systems: A Case Study of Sri Lanka

Abstract

Sustainable management of municipal solid waste (MSW) is a critical issue around the world, especially in South Asia where waste generation is expected to double by 2050. Closing the food-nutrient cycle through composting biodegradable MSW has the potential to meet human needs, including sanitation and food security, while protecting the environment. We use an interdisciplinary case study approach including systems thinking to assess Sri Lanka's national MSW composting system, which primarily receives residential and commercial food waste. We embed quantitative compost quality analysis and interviews at 20 composting facilities within a broader qualitative assessment informed by ~60 stakeholders in total. This approach yields insights on how institutional, economic, social, and biophysical aspects of the system are interrelated, and how challenges and solutions can create undesirable and desirable cascading effects, respectively. Such dynamics can create risks of composting facility failure and unintended consequences, diminishing the chances of achieving a sustainable circular food–nutrient system. Compost quality, which was variable, plays a pivotal role within the system—a function of program design and implementation, as well as a determinant of value capture in a circular economy. We make several recommendations to inform future efforts to sustainably manage biodegradable MSW using composting, drawing on our case study of Sri Lanka and prior case studies from other nations. Key among these is the need for increased emphasis on compost product quality and markets in policy and program design and implementation. Targeted measures are needed to improve waste separation, boost compost quality, effectively use compost standards, encourage compost market development, ringfence the revenues generated at municipal compost plants, and identify efficient modes of compost distribution. Such measures require adequate space and infrastructure for composting, resource investment, local expertise to guide effective system management, strong links with the agriculture sector, and continued political support.

Microplastics in composts, digestates, and food wastes: A review

“…To date, there are no standardized methods for measuring microplastics in composts, digestates, and food waste. Methods for measuring microplastics in solid organic matrices such as these typically involve a sequence of steps aimed at isolating, identifying, and characterizing the microplastics in each sample (Ruggero et al, 2020). Isolation methods include flotation, elutriation, centrifugation, digestion (with e.g., H 2 O 2 , Fenton's reagent), and sieving (Junhao et al, 2021;Ruggero et al, 2020).…”

“…In addition to the potential risks posed to human and ecosystem health, there is early evidence to suggest that some microplastics have an inhibitory effect on the composting and anaerobic digestion processes (J. Zhang et al., 2020a; Y. Zhou et al., 2022), thereby possibly reducing the intended benefits of food waste diversion initiatives. Furthermore, plastic contamination can impede circular economy efforts by making composts and digestates less attractive to farmers and consumers (Friege & Eger, 2021; Roy et al., 2021). “Biodegradable” and “compostable” plastics have been touted as a more environmentally friendly alternative to conventional petroleum‐based plastics (European Commission, 2018; Folino et al., 2020; Shaikh et al., 2021), but are problematic for multiple reasons and do not yet represent a clear solution (Calabrò & Grosso, 2018; Haider et al., 2019; Markowicz & Szymańska‐Pulikowska, 2019; Serrano‐Ruiz et al., 2021).…”

“…Zhou et al, 2022), thereby possibly reducing the intended benefits of food waste diversion initiatives. Furthermore, plastic contamination can impede circular economy efforts by making composts and digestates less attractive to farmers and consumers (Friege & Eger, 2021;Roy et al, 2021). "Biodegradable" and "compostable" plastics have been touted as a more environmentally friendly alternative to conventional petroleum-based plastics (European Commission, 2018;Folino et al, 2020;Shaikh et al, 2021), but are problematic for multiple reasons and do…”

From By-Products to Fertilizer: Chemical Characterization Using UPLC-QToF-MS via Suspect and Non-Target Screening Strategies

“…Thus, the recycling of fertilizer components through composting, as well as the diminished environmental impact due to lowering transportation needs, render this approach as an appealing alternative paving the way towards cyclic economy [ 7 , 8 ]. Last but not least, such approaches offer cost-effective alternatives for poor countries [ 9 ].…”

Quality Assessment of Composts from different Organic sources

“…In our study, both these parameters were analyzed for the quality assessment of compost. Compost quality is also related to the macronutrient content present in compost which is Nitrogen, Phosphorus, and Potassium [6]. The benefit of using compost in agriculture is based on the availability of these nutrients forplant.…”