Compost-hosted microplastics - municipal solid waste compost

Owing to their ubiquitous distribution in various ecosystems, microplastics (MPs) have recently gained enormous attention from the scientific community. However, most MP-related research focuses on the marine ecosystem. MP impacts on terrestrial ecosystems, animals, plants, and agriculture have not been studied adequately. In most countries, low-cost compost is produced on a large scale, using municipal solid waste (MSW) as the raw material. Due to lack of pre-sorting process, MSW compost contains MPs. The size and shape of MPs in MSW compost changes with the mechanical crushing, anaerobic and aerobic processes in composting. The most common method of composting in developing countries, windrow composting, results break down of plastics into ultra small MPs, and separating them from MSW compost is almost impossible. Therefore, MSW compost acts as a main source for MPs contamination in soil. Furthermore, high surface area of MPs facilitates the adsorption of chemical contaminants available in the surrounding environments. Therefore, MPs can act as vectors and transport toxic contaminants into different environmental matrices. These chemicals can cause adverse impacts on plants and animals by inhibiting their growth, reducing seed germination rate, accumulating and transferring through food chains. This chapter provides a general overview of the characteristics of MPs from MSW compost produced in different countries and their impact on soil physical, chemical, and biological properties. Finally, the chapter summarizes the negative effects of MP-bound pollutants on agriculture and provides suggestions to prevent MP contamination in the environment using remediation strategies to minimize their environmental impact.