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

question 11

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

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