METHOD OF ALKALINE SEWAGE TREATMENT, INORGANIC COAGULANT FOR ALKALINE SEWAGE TREATMENT AND METHOD OF ITS PREPARING Russian patent published in 1997 - IPC

FIELD: technology of sewage treatment. SUBSTANCE: hematite from clay production is treated with 3-5% hydrochloric acid and obtained solid residue is treated with 50-55% sulfuric acid. Obtained pulp is filtered and concentrated sulfuric acid is added to the obtained solution up to its total concentration 25-50% in solution. Prepared solution is kept for 10-20 h and the formed precipitate is separated. Precipitate is inorganic coagulant containing the following components, wt.-%: mixture Al₂(SO₄)₃•nH₂O where n = 6, 12, 14 and Al₂(SO₄)₃•H₂SO₄•12H₂O as measured for Al₂O₃ 2-10; FeSO₄•H₂O as measured for Fe₂O₃ 2-10; total H₂SO₄ 40-60 (including free H₂SO₄ 20-40) and H₂O of crystallization up to 100%. Alkaline sewage were treated with the obtained coagulant. EFFECT: improved method of treatment, enhanced quality of coagulant. 3 cl, 2 tbl