Preparation of Fe/C-MgCO3 micro-electrolysis fillers and mechanism of phosphorus removal.

Abstract

Iron-carbon micro-electrolysis is effective for the removal of phosphorus in wastewater; however, meeting the stringent emission standards required for treatment is difficult. To meet these treatment standards, modified micro-electrolytic fillers were prepared from iron dust, powdered activated carbon, clay, and additives using an elevated temperature roasting process under an inert atmosphere. The results show that among several additives, the modified micro-electrolytic (Fe/C-MgCO3) fillers using MgCO3 were the most effective at phosphorus removal. The preparation conditions for the Fe/C-MgCO3 fillers and their effects on phosphorus removal performance were investigated. Under the optimal preparation conditions (calcination temperature: 800°C, Fe/C = 4:1, clay content 20%, and 5% MgCO3), the filler yielded a high compressive strength of 3.5MPa, 1h water absorption rate of 25.7%, and specific surface area and apparent density of 154.2 m2/g and 2689.2kg/m3, respectively. The iron-carbon micro-electrolysis process removed 97% of phosphorus in the wastewater by using the Fe/C-MgCO3 fillers, which was 14% more than the Fe/C filler. Electrostatic adsorption and surface precipitation were identified as the main phosphorus removal mechanisms, and the surface of the Fe/C-MgCO3 filler was continuously updated. These results demonstrated that Fe/C-MgCO3 is a promising filler for phosphorus removal in water treatment.