Fixed-bed studies of landfill leachate treatment using chitosan-coated carbon composite

Abstract

The feasibility of a chitosan-coated coconut-shell (CS) carbon composite for landfill leachate treatment in a fixed-bed study was investigated in terms of COD and NH3-N removal. The surface of the composite was characterized using SEM, FT-IR, and XRD to assess any changes before and after column operations. To enhance its cost-effectiveness, the saturated composite was regenerated using NaOH. The results showed that the composite had significantly better removal of both COD and NH3-N, as compared to CS and/or chitosan (p ≤ 0.05; ANOVA test), respectively. The breakthrough curve obtained from the fixed-bed studies exhibited an ideal “S” shape. The breakthrough points for the adsorbents followed the order of CS at BV 76 < chitosan at 200 BV < composite at BV 305. It was also found that a low flow rate and deeper bed depth of the packed adsorbent were necessary for achieving optimal column operations. The composite achieved 96% regeneration in the first cycle. However, even with the enhanced adsorption of target pollutants by the composite through chitosan coating, the treated effluents still could not meet the required COD and NH3-N effluent limits of less than 200 and 5 mg/L, respectively, as mandated by legislation. Nonetheless, the findings suggest that low-cost composites derived from unused resources can be employed as effective adsorbents for wastewater treatment.