METHOD OF REMOVING CHROMIUM COMPOUNDS FROM WASTE WATER AFTER LEACHING WASTE OF CHROME TANNED HIDE AND RECOVERING CHROME TANNING COMPLEXES IN FORM OF CHROME SALTS

摘要

The invention can be characterised in that chromates present in the wastewater are reduced in acid medium by pyrosulphite to obtain chrome salts which are then precipitated in a moderate alk. medium such as low-soluble chromic hydroxide separable by means of filtration. Chromic hydroxide is, prior to addition of activated carbon, extracted by diluted sulphuric acid. The chrome salts thereby obtained are usable for the preparation of chrome tan-liquor.