Recovery phosphate and ammonium from aqueous solution by the process of electrochemically decomposing dolomite

Abstract The cost-effective recovery of phosphate is of great significance to the mitigation of phosphorus resource depletion crisis. The electrochemical-decomposition of dolomite was developed to recover phosphate and ammonium from aqueous solution. The dolomite ore is mainly composed of CaMg(CO3)2 (53.73%), CaCO3 (28.93%) and SiO2 (16.59%). The continuous release of Mg2+ and Ca2+ were achieved by electrochemically decomposing dolomite ore, accompanied by the generation of base solution (9.0 ∼ 10.5). The main factors affecting the recovery performance of phosphate (PO4-P) and ammonium (NH4-N) are current, initial concentration of PO4-P and NH4-N, initial pH of feed solution and feed rate. For a 30-d operation, the recovery rate of PO4-P was maintained at 90 ∼ 97% and that of NH4-N at 50 ∼ 60% under optimized operating conditions. The recovered product had low water solubility but high citric-acid-soluble, and was proposed as a slow-release fertilizer for crops. The proposed process as a simple, effective and green route may serve as a new strategy for recovering PO4-P and NH4-N from wastewaters.