Recovery phosphate and ammonium from aqueous solution by the process of electrochemically decomposing dolomite
2021
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.
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