Adsorption Filtration Technology Using Reclaimed Iron Sludge Coated Sand Filter Media for Municipal Wastewater Reuse

Abstract

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 pHZPC of RISCS was about 7.1, favoring the adsorption of negatively charged particulate onto the RISCS surface. At 20℃, the applicability of the isotherm models for the experimental data follows the order: Freundlich≈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 PO43- than QS. The results of filtration experiments show that, the removal of COD, PO43- 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 (GB/T 18920-2002) in China.