Characterization of solid organic waste and leachate from Piyungan Integrated Waste Management Site

Abstract

This study characterized solid organic waste and leachate at the Piyungan Integrated Solid Waste Management (ISWM) facility to evaluate their potential use as organic fertilizer and soil conditioners. Solid waste samples were collected from three age categories (0-6 months, 7-18 months, and 2-3 years), and leachate was collected from the inlets and outlets of both the old and transition Leachate Treatment Installations (LTIs). The analyzed parameters included pH, organic C, C/N ratio, macro- and micro-nutrients, and heavy metals. The 7-18-month waste category showed the most promising quality, with neutral pH (7.17), 19.26% organic C, and 2.46% total nutrients, although its C/N ratio (46.62) and Pb concentration (99.83 ppm) exceeded standard limits. Waste aged 2-3 years exhibited greater stability (C/N 20.36; pH 7.09) but contained very low organic C (3.21%), while the 0-6-month material had an excessively high C/N ratio (301.90). Leachate samples showed slightly alkaline pH (7.68-8.34) and organic C levels of 9.98-29.93%, with Pb and Cd remaining below safety thresholds, although micronutrient concentrations were substantially below the standard range for liquid soil conditioners. Overall, solid waste aged ≥7 months demonstrates potential for use as fertilizer or soil conditioner following Pb reduction and C/N adjustment, whereas leachate exhibits limited applicability as an alternative soil conditioner. Further process optimization is required to ensure safe and compliant utilization.