Reuse Rate Improvement of Wastewater Through Effective Removal and Recovery of High Concentration Phosphorus in Reverse Osmosis Concentrate and Food Waste Leachates

Phosphorus can only be obtained from phosphate ore, and the price of phosphate ore is gradually increasing because of the limited phosphate ore reserves. The global population is continually increasing and is predicted to rise to approximately 9.1 billion people by 2040. Therefore, phosphorus is being increasingly consumed because it is an essential component of fertilizer. Numerous studies have researched methods to recover phosphorus. Among these methods, the crystallization technique has the most advantages compared to other methods (chemical, physical, and biological treatments). Struvite and calcium phosphate crystals are typically used for phosphorus recovery. Struvite was created by combining a 1:1:1 molar ratio of NH₄⁺, PO₄³⁻, and Mg²⁺. For struvite crystallization, we performed diverse experiments focusing on pH range, seed types, and the injection amount of various chemicals (CaO and MgO). We found that a pH of 9 and injecting 0.3 g of CaO and MgO into 240 mL of wastewater were ideal for struvite crystallization. We also performed experiments on calcium phosphate crystallization using calcium silicate hydrate (CSH) compared to other calcium compounds and found that CSH was the best compound to use for phosphate crystallization.