Abstract
— This study examines the use of calcium hydroxide [Ca(OH)₂] as an alkaline treatment agent for the simultaneous removal of phosphate and metal ions from municipal wastewater. A series of batch experiments was conducted to optimize Ca(OH)₂ dosage, mixing speed, and contact time, with pH monitored to understand system behavior and precipitation dynamics. Increasing Ca(OH)₂ dosage elevated pH substantially, promoting phosphate removal through the formation of calcium phosphate. Metal ion removal similarly improved at higher pH levels, where hydroxide precipitation becomes thermodynamically favorable. The results demonstrate that controlled alkalization can support efficient multi-contaminant removal while minimizing chemical consumption and sludge formation. Overall, the study provides a practical framework for developing low-cost, sustainable wastewater treatment strategies that are particularly suitable for municipalities operating under resource constraints.