Utilisation of waste gas sludge for waste water treatment

Abstract

This hypothesis driven research investigated the removal of Cu, Fe, Zn and Mn from synthetic metal solutions and real Acid Mine Drainage (AMD) from Wheal Jane mine in West Cornwall UK, employing waste gas sludge (BOS sludge) which is an end waste reside generated from steel production. Batch experiments showed the efficiency and adsorption rates increased with reduction in BOS sludge particle size, lower in initial metal concentration, increase in BOS sludge dosage, an increase in initial pH and increase in agitation speed. Fitting of the Langmuir isotherm model to experimental data gave a good fit with correlation coefficients R$^2$≥0.99 and the selectivity series of BOS sludge was: Cu$^2$$^+$>Fe$^3$$^+$>Zn$^2$$^+$>Mn$^2$$^+$. For single and multiadsorbate systems, a Pseudo second order model was the most appropriate theory to satisfactorily describe experimental data and the rate limiting step for this process was chemisorption. Adsorption was spontaneous and high pH promoted adsorption possibly by precipitation and/or ion exchange processes which had taken place between the exchangeable cations present in BOS and solutions. Results from the treatment of real and synthetic AMD solutions revealed that BOS sludge worked well and hence BOS sludge as a novel low cost material could be used as a sustainable sorbent in AMD treatment technologies