Evaluating Municipal Solid Waste-Derived Vermicompost for Soil Improvement, Plant Performance, and Associated Health...

The management of municipal solid waste (MSW) is a global challenge, and composting provides a sustainable solution for converting organic fractions into compost. This study investigated the effects of municipal solid waste vermicompost (MSW_VC) on soil properties, morphological, biochemical and HM accumulation in spinach, along with associated human health risks. Pot experiments were conducted with six treatments: 20% (T1), 40% (T2), 60% (T3), 80% (T4) MSW_VC doses, inorganic fertilizer (IF), and control (T0). Soil analyses revealed significant (p < 0.05) improvements in soil pH, TOC, TKN, and available phosphorus under MSW_VC amendments. Biochemical parameters, including chlorophyll, carotenoids, protein, ascorbic, phenolics, and proline, were enhanced at moderate doses (20-40%) (p < 0.05) at 45 days after sowing (DAS). However, higher doses (> 60%) elevated lipid peroxidation and stress responses to HM. BCF indicated that Pb and Cu accumulation decreased with increasing MSW_VC (p > 0.05), whereas Zn and Ni exhibited higher root and shoot uptake (p < 0.05). The TF showed a declining trend for Pb and Cr, whereas Ni and Zn increased at higher doses. The human health risk assessment revealed non-carcinogenic risks within safe limits (THQ < 1). However, the additive impact of HM (HI) suggested a potential risk at higher doses of MSW_VC T4 (HI= 0.99 and HI= 1.38) in both children and adults. Overall, while MSW_VC enhances soil properties, application must be carefully controlled to balance agricultural benefits against toxicity and food safety risks.