Adsorption filtration technology using reclaimed iron sludge coated sand filter media for municipal wastewater reuse

This paper aims at exploring the feasibility of adsorption filtration technology using reclaimed iron sludge coated sand (RISCS) as filter media for municipal wastewater reuse. The iron sludge as surplus waste solution derived from ferric-carbon micro-electrolysis process. Scanning electron microscope (SEM), Infrared spectroscopy (IR) and X-ray diffraction (XRD) analysis were used to investigate the surface morphology of quartz sand (QS) and RISCS. Batch experiments were performed using QS and RISCS to examine the adsorption isotherms of phosphate and the effect of their dosages on UV₂₅₄ removal The results show that RISCS had significantly rougher surfaces, more micropores than QS, and there exist iron oxides (hematite and goethite) on the surface of RISCS. The pH_ZPC of RISCS was about 7.1, favoring the adsorption of negatively charged particulate onto the RISCS surface. At 20 °C, the applicability of the isotherm models for the experimental data follows the order: Freundlichs≈Langmuir > Temkin. The Langmuir adsorption capacity for RISCS and QS was 0.0187mg/g and 0.0039mg/g, respectively. RISCS has a much higher affinity for PO₄^3- than QS. The results of filtration experiments show that, the removal of COD, PO₄ ^3- and UV₂₅₄ by RISCS filtration was higher 7.8%, 25.1% and 5.8% than QS filtration, respectively. Effluent quality by RISCS filtration can meet the requirements of <Municipal wastewater reusemiscellaneous water quality> (GB/T 18920-2002) in China.