Removal of heavy metals from wastewater using coagulation-flocculation: A case study of mining chemical analysis laboratory effluents

The removal of heavy metals from contaminated water is a critical environmental challenge. This study investigates the effectiveness of calcium oxide and cactus juice as treatment methods for the removal of magnesium (Mg), iron (Fe), aluminum (Al), and cadmium (Cd) chemical analysis laboratory wastewater. Experimental results demonstrate that increasing doses of calcium oxide significantly reduce the concentrations of Mg and Cd, with Fe being completely removed even at lower dosages. The pH of the treated solutions increased markedly with higher calcium oxide doses, indicating effective neutralization of acidity. In parallel, cactus juice was tested as a natural coagulant, showing substantial reductions in Mg, Fe, Al, and Cd concentrations while maintaining stable pH levels. Conductivity measurements revealed a steady decline with increasing doses of cactus juice, corresponding to a decrease in the ionic content of the solution. These findings highlight the potential of both calcium oxide and cactus juice as environmentally friendly and effective treatment options for heavy metal contaminated water. When combined, the addition of calcium oxide as a coagulant and cactus juice as a flocculant resulted in significant reductions in Mg and Cd concentrations across different pH levels. At pH levels ranging from 6.388 to 11.242, Fe and Al concentrations remained undetectable, indicating highly effective removal. Cd concentration decreased from 29.2 ppm at pH 6.388 to 0.00 ppm at higher pH levels. Conductivity remained consistent at 34 mS/cm, while BPL (Base Precipitation Lime) concentration showed a gradual decline with increasing pH.