Advances in remediation techniques for polluted soils and groundwater

Abstract

The removal of chemical oxygen demand (COD) from fish pond wastewater using waste alum sludge from the water treatment plant was studied in a continuous flow system. Characterization of the sludge revealed the Braunuer Emmet Teller (BET) results with a surface area of 139 cm2/g, pore volume of 0.126, and mesoporous pore radius of 5.228 nm. The Fourier Transform Infrared spectroscopy (FT-IR) analysis indicates ─OH bonding to inorganic matter and for the loaded sludge around 2361 cm-1 attributed to vibration of sulfur-hydrogen interaction (S─H) in the sludge matrix. The effect of varied bed height and influent flow rate on the shape and characteristics of breakthrough curves were determined. At a constant influent concentration of 72 mg/L, results confirmed that early bed saturation and breakthrough time occurred at higher flow rates and smaller bed depths. The optimum COD removal of 70.25% was obtained at a flow rate of 3 mL/min and 50 mm bed depth and the maximum adsorption capacity of 53.98 mg/g was obtained at a 7 mL/min flow rate and 50 mm bed depth. The adsorption data were fitted into Thomas, Yoon Nelson, Adams Bohart, Bed Depth Service Time, and Clark’s model. Based on regression and SS error analysis, Clark's model best described the adsorption of COD by alum sludge at all conditions. It can be deduced from the results obtained that waste alum sludge is a suitable adsorbent for the treatment of fish pond wastewater.