Urban dimension of microplastics in municipal solid waste compost within an emerging eastern Indian city

Abstract

Composting processes are widely used to treat organic portion of Municipal Solid Waste (MSW) in urban areas. In the present work, mapping of Microplastics (MPs) in the organic portion of municipal solid waste of a progressive smart city in eastern India was undertaken based on its socio-economic functionality. Samples were collected from five different composting stations during two broad stages of composting operation. The suspected MPs were identified using a combination of Stereomicroscope, ATR-FTIR and Raman spectroscopy. Mean abundance of MPs varied from 1111 +/- 83 items/kg at Predominantly Slum (P-S) to 2111 +/- 164 items/kg at Predominantly Residential (P-R) area. Polyethylene (PE) was the dominant type of polymer detected in compost samples. Most of isolated MPs were within the size range of < 1 mm (33%). Films were the predominant form of MPs found at Predominantly Academic/Educational (P-A/E), Predominantly Residential (P-R), Predominantly Industrial (P-I), Predominantly Commercial (P-C) area, while the fragments were dominant at Predominantly Slum (P-S). A total of five different colours of MPs were identified with the majority being transparent in nature. The Polymer Hazard Index (PHI) of P-A/E and P-C were > 1000 (hazard category V); and Potential Ecological Risk Index (PERI) were > 1200 for all the sampled sites reflecting potential risk associated with MP pollution. The findings of present study shall be crucial for stakeholders to device effective strategies towards managing MPs in compostable fraction of MSW.