APPLICABILITY OF CRUSHED CLAY BRICK AND MUNICIPAL SOLID WASTE SLAG AS LOW-COST ADSORBENTS TO REFINE HIGH CONCENTRATE Cd (II) AND Pb (II) CONTAMINATED WASTEWATER

Along with population growth, rapid urbanization, and industrialization, the generation of waste and industrial by-products is increasing enormously and causing many environmental and social issues. In order to examine effective applications of waste and industrial by-products, this study aimed to investigate the effective use of crushed waste clay bricks (CCB) and municipal solid waste slag (MSWS) as low-cost adsorbents to treat high concentrated wastewater. A series of batch adsorption experiments were carried out to investigate the effects of contact time, initial concentration, pH, ionic strength, and competitive metals on Cd2+ and Pb2+ adsorption onto the tested adsorbents. The Langmuir model performed well by the fitting Cd2+ and Pb2+ adsorption isotherms. The maximum adsorption capacity of Pb2+ (3.4-5.5 mg/g) was higher than the Cd2+ (2.3-3.2 mg/g) for both adsorbents. CCB showed high removal of metals, but a higher dependency on the metal system (single, binary, or multi-metals). Interestingly, MSWS showed lower removal of metals but less dependency on the metal system for Cd2+ and Pb2+. Adsorption of tested adsorbents was mainly controlled by deprotonation or ion exchange at the natural pH, and at the higher pH (>9 for Cd2+ and >7 for Pb2+), surface precipitation was the predominant mechanism for Cd2+ and Pb2+ removal (>60%). Overall, tested adsorbents were showed comparatively good performance in treating high concentrated wastewater, but future studies under different conditions and with modification to apply CCB and MSWS fines as better low-cost adsorbents to treat wastewater are essential.