REDUCING METHOD OF SLUDGE DISCHARGED FROM NEUTRALIZATION OF PHOSPHORIC ACID WASTEWATER

摘要

PURPOSE: A reducing method of sludge discharged from neutralization treatment of phosphoric acid wastewater is provided, which can reutilize the waste from steel work and reduce consumption of hydrated lime and discharge amount of sludge. CONSTITUTION: The method comprises as follows: (i) dip waste containing line and magnesium in water and agitate for at least 5 min.; (ii) extract the supernatant which contains lime and magnesium and the pH of which is more than 10; and (iii) neutralize the SO4-2, F- and PO4-3 containing wastewater that is discharged from phosphoric acid manufacturing plant with the extracted solution to form calcium phosphate, calcium fluoride and calcium sulfate precipitates that are discharged as sludge.