Process intensification of chemical phosphorus removal in a microreaction system

Serious problems including excessive ferric salt dose, high effluent phosphorus concentration and long handling time are encountered for chemical phosphorus removal by ferric salt in batch processes due to poor mixing performance. In this work, we develop a microreaction system to intensify phosphorus removal process using ferric chloride by achieving rapid mixing. Phosphorus residual is remarkably reduced by optimizing mixingrelated factors, including flow rate, contacting mode, device structures and flow rate ratio which is justified by CFD simulation. The results show that phosphorus removal performance is not sensitive to flow rate ratio. Phosphorus residual can be lower than 0.20 mg/L at [P]0 = 6 mg/L, pH = 6.0, Fe/P = 1.8 and residence time = 42.8 s. Compared with batch processes, the microreaction system has several advantages including much lower phosphorus residual, lower ferric salt dose, shorter processing time and larger handling capacity. Moreover, a machine learning model is established to predict the device performance with high accuracy.