Isotherm and kinetic modelling for assessing the effectiveness of economical adsorbents in sewage water treatment

Abstract

In the face of growing environmental challenges and the urgent need for sustainable solutions, this research delves into an innovative approach to wastewater treatment by harnessing the power of agricultural waste materials as efficient adsorbents. The focuses on mitigating water pollution and bringing irrigation water quality in line with strict maximum permissible limits (MPLs). Initial assessments revealed elevated levels of contaminants, all exceeding MPLs. Among ten adsorbent materials tested, Rice Husk Ash (RHA), Sugarcane Bagasse (SB), and Ferric Oxide Sand (Fe-S), emerged as highly effective materials, achieving maximum reductions. Optimized conditions for adsorbent dosage, contact time, and wastewater load were identified which was 2.0 g of adsorbent, 250 mL of sewage water load at 15 min contact time. RHA demonstrated a remarkable 60-75% reduction in BOD, 52-67% in COD, and over 100% in RSC reduction. SB achieved reductions of 57-67% in BOD, 47-59% in COD, and 41-76% in RSC. Fe-S delivered significant reductions in COD (51-61%) and nearly 100% in RSC reduction. Kinetic studies confirmed pseudo-second-order kinetics as the dominant adsorption mechanism, with correlation coefficients (R²) exceeding 0.98, further supporting the effectiveness of these adsorbents. This research underscores the potential of agricultural waste-based adsorbents, especially RHA and SB, in treating sewage water pollutants and making it fit for irrigation.