Chemical Treatment of Municipal Water Supplies Commonly Entails Use of CaO,Al₂(SO₄)₃,and

Multiple Choice

Chemical treatment of municipal water supplies commonly entails use of CaO,Al₂(SO₄) ₃,and Cl₂.The purpose of adding CaO is to ________.

A) remove all HCO₃^- as solid CaCO₃
B) remove all SO₄^2- as solid CaSO₄
C) remove all Cl^- as solid CaCl₂
D) selectively kill anaerobic (but not aerobic) bacteria
E) make the water slightly basic so that addition of Al₂(SO₄) ₃ will afford a gelatinous precipitate of Al(OH) ₃