METHOD FOR RECOVERING COAGULANTS FROM CHEMICAL WASTEWATER FROM WATER AND WASTE WATER TREATMENT PLANTS

摘要

The present invention pertains to a method of recovering coagulants from sludge from chemical precipitation in water and waste water treatment plants wherein concentrated sulfuric acid is added to sai sludge, after conventional dewatering and drying of the sludge, in such an amount that the majority of the carbon bound in organic com pounds and substances is converted into elemental carbon, and that the aluminum and/or iron hydroxide in the sludge is converted into the corresponding sulfates, and that water formed during the reaction, and possible remaining water after the drying, is evaporated. In an especially advantageous embodiment water is added to the reaction products, where after remaining suspended substances in the solution are removed by filtration.