Two subjects in chemical phosphate removal were investigated in this study: rapid mixing and modeling. Evaluation of rapid-mixing parameters showed that chemical phosphate removal is affected by the mixing intensity, the mixing time, and aluminum solution strength. Phosphate removal efficiency improved as the mixing intensity increased from a mean velocity gradient (G) value of 150 to 600 sec[superscript]-1. Further increase in a G value was not accompanied by improvement of phosphate removal efficiency. This indicates that an optimum mixing intensity for chemical phosphate removal is a G value of 600 sec[superscript]-1. The effect of the mixing time was found insignificant when it was in the range of 10-60 seconds. After that, phosphate removal efficiency deteriorated over time when the mixing time was increased up to 180 seconds. The time trend was found to be linear and constant at G values of 500-1000 sec[superscript]-1. The higher the aluminum solution strength, the better was the phosphate removal efficiency;The modeling study found that phosphates were removed by forming aluminum hydroxyphosphate, Al[subscript]1.2H[subscript]2PO[subscript]4(OH)[subscript]2.6, rather than aluminum phosphate in chemical phosphate removal. It was also shown that calcium-phosphate precipitation could occur at an initial stage of chemical phosphate removal when calcium was present in the wastewater. The precipitates could be tricalcium phosphate. Aluminum chloride and alum were compared in their effects on chemical phosphate removal. There was no difference between use of these two chemicals. Evaluation of the Ferguson model for phosphate removal revealed that the Ferguson model predicted the residual phosphate values well. However, the model was found to be more like data fitting because it did not incorporate complexes and cannot account for use of different chemical effects. Regression models were developed for the residual alkalinity, pH, and phosphate. These regression models predicted the residual parameters well.