Microplastics (MPs) have been identified as an emerging soil pollutant and a global environmental concern. Scientists have recently paid attention to the contamination of soil by MPs as their detrimental impacts on soil systems are largely unknown. MPs are considered to be vectors for other soil contaminants, such as potentially toxic elements (PTEs) and organic contaminants. PTEs are persistent contaminants and are often released into soils in large quantities. MPs adsorb PTEs, mainly via electrostatic attraction and surface complexation, and increase their mobility in soils. These complexes can be easily absorbed by plants; hence, the accumulation of PTEs in plants can be enhanced in both microplastic and PTE contaminated soils. Furthermore, there is a high risk of food chains contamination by PTEs due to crops grown in both microplastic and PTE-contaminated soils. Consequently, countermeasures including policy- and governance-based approaches that target circular economy as well as reduce, reuse, recycle (3R) applications are being discussed around the world to minimize the environmental contamination of MPs.

Due to its ability to recover both material and energy from organic waste, biogas technology is considered the best technology for treating organic waste. While in many emerging Asian countries more than 50% of municipal waste is organic waste, the amount of organic waste treated with biogas technology remains very limited. This study identified key challenges faced by practitioners in sustaining biogas plants from literature and interviewed a number of sustainably operating biogas plant managers and, based on the findings, developed an implementation framework to help decision makers and practitioners in planning a sustainable municipal organic waste biogas plant facility.

No abstract

Source separation plays a pivotal role in sustainable and integrated Municipal Solid Waste Management (MSWM) and in achieving a circular economy in Asia. However, it is still not an official practice, and many cities continue to utilise open dumping, involving receiving mixed waste without pre-treatment. This paper, therefore, examines the advantages of source separation of MSW and explores the main factors for success in the planning and implementation of official source separation programmes in cities in Asia. Analysis of the results for two case studies in India and Japan could be used to strengthen capacities of policymakers in designing and implementing official source separation systems to facilitate material recovery and achieve sustainable development in Asia.

The solid waste sector is a significant contributor to methane (CH 4 ) emissions with a global warming potential (GWP) of 21 times more than that of CO 2 bringing the need for preventive actions from this sector. In the recent years, composting projects both centralized and decentralized have proved to be addressing this issue. However, much of the decentralized composting projects failed due to their financial and other operational constraints that arise during the course of the implementation. On this regard, the current article reviews the potential of carbon finance as an opportunity for funding decentralized composting projects through demonstrating the application through emission calculation of four cities in Asia. On assessing the emissions, it also identifies the benefits associated with the emissions reduction from the composting projects which might not be available in the absence of the projects. The article also discusses the various carbon financing strategies available in the present market to identify the potential market for inclusion of decentralized composting projects. In the process, the article identifies the issues in the implementation of decentralized composting projects under Clean Development Mechanism (CDM) and other carbon markets in general.