TREATMENT OF AQUEOUS EFFLUENT FROM CHLORINE OR CHLORINE COMPOUND PULP BLEACHING PROCESS AND RECOVERY OF BLEACHING CHEMICALS THEREFROM

摘要

A closed-circuit process for the treatment of aqueous effluent from a chlorine or chlorine compound pulp bleaching process to recover bleaching chemicals therefrom comprises raising the pH of the effluent in acidic form with a neutralizing base capable of reacting with chlorine compounds contained in the acidic effluent to form a neutralized effluent containing a salt capable of being thermally decomposed to form hydrogen chloride and a residual base, concentrating the neutralized effluent to form a concentrated brine, heating the concentrated brine to decompose the salt thereby releasing gaseous hydrogen chloride and forming the residual base, and recovering the released hydrogen chloride and the residual base separately from one another.