metallsulfate as flocculants for wastewater treatment and its manufacture

摘要

A clarificant of wastewater comprises an aqueous solution of a polynuclear complex salt comprising sulfates of a plurality of the metals K, Fe, Ca, Na, Mg and Al, e.g. containing per 1000 ml of water 0.78-5.63 g K+ ions, 6.00-72.60 g Fe++, 0.12-1.20 g Ca++, 0.10-1.00 g Na+, 6.56-19-70 g Mg++, 6.21-35.00 g Al+++ and 106.08-463.77 g SO4-- ions. It is prepared by heating, e.g. at 100 DEG - 190 DEG C and a pressure of 1 to 10.0 kgf/cm2, isochorically an aqueous solution containing the said mixture of sulfates, e.g. containing 0.02-0.08 M K+, 0.11-1.31 M Fe++, 0.003-0.30 M Ca++, 0.004-0.40 M Na+, 0.27-0.81 M Mg++ and 0.370-1.300 Al+++. The solution is added to and rapidly stirred with wastewater to adjust its pH to 4-5 and an alkali, e.g. Ca(OH)2, is added until the pH is 6-8.5, so as to flocculate nearly all the suspended contaminants and the floc is removed. The wastewater treated can be industrial or domestic effluent water or natural water, and there is thus obtained a reduction in biological and chemical oxygen demands and in suspended solids.