Reusability of iron oxyhydroxide agglomerates adsorbent for repetitive phosphate removal

Phosphate release to receiving water bodies promotes eutrophication. Therefore it is a common practice to remove phosphate from domestic wastewater. Yet, the conventional secondary treatment most often require a polishing step as to comply with rigorous regulations. Semi-batch adsorption experiments demonstrated the feasibility of phosphate removal, from synthetic secondary effluent, by adsorption onto iron oxyhydroxide agglomerates (IOAs) in a submerged membrane reactor. Sedimentation of the IOAs, their regeneration and reusability were investigated. Additionally, the reuse of the desorbing solution was examined. Techno-economic evaluation of the cost of chemicals required for synthesis and regeneration of the IOAs is presented. The potential application of the IOAs as a renewable adsorbent was demonstrated by the high adsorption capacity which was not significantly changed with the adsorption/regeneration cycle number (about 93% of initial adsorption capacity was obtained in the fifth adsorption cycle) as well as the lower chemical cost of IOAs regeneration as compared to their synthesis.