Impact of Sugarcane Bagasse Ash Amendment on Soil Attenuation aand Leachate Dynamics: Insights from Multivariate Analysis

Abstract

Landfill leachate composition is strongly governed by soil–leachate interactions that control contaminant mobility, attenuation, and long-term environmental impact. The study demonstrates the influence of Sugarcane Bagasse Ash (SCBA) amended soil on leachate quality through controlled lysimeter experiments and comparative validation with field leachate characteristics from a municipal solid waste (MSW) landfill site and with a developed prototype model. Two cover soil configurations were examined: (i) loam soil and (ii) clay loam amended with SCBA. Simulated rainfall was applied by adding 5 L of water weekly over a 17-week monitoring period and collected leachate was analysed for physicochemical parameters including pH, electrical conductivity (EC), total dissolved solids (TDS), hardness, chloride, biochemical oxygen demand (BOD), and chemical oxygen demand (COD). Results indicate that the SCBA-amended clay loam significantly improved contaminant attenuation compared to un-amended loam soil, producing lower EC, TDS, hardness, chloride, BOD, and COD values. The observed reduction is attributed to enhanced adsorption, cation exchange capacity, filtration effects, secondary mineral formation, and accelerated organic degradation mechanisms induced by SCBA incorporation. Experimental findings were further validated against the actual physicochemical characteristics of leachate collected from an operational MSW landfill site under similar ground conditions. A Multivariate statistical analyses were employed to interpret the governing processes. Pearson correlation analysis revealed strong relationships among key parameters, notably EC, Total Hardness–Mg, and COD–BOD at p < 0.01, highlighting coupled mineralisation and organic degradation pathways. A constitutive model developed in the laboratory to simulate soil–leachate interaction behaviour showed good agreement with both experimental and field observations, confirming the reliability of the proposed attenuation mechanism.