Removal of AOX FRM bleach plant mill effluents by pH shift using the alkalinity/acidity sources available at the mill

Abstract

A process for removal of adsorbable organic chlorine (AOX) in which the acid-soluble AOX present in kraft chlorination (C.sub.D) effluents are destablized and converted to inorganic chloride by pH shift using the alkalinity and acidity sources available at the mill; C.sub.D effluent, typically having a pH of 1-2 and E.sub.1 effluent, typically having a pH of 9-12 can be mixed in various proportions to achieve a pH between 6.5-9.0 or the C.sub.D effluent is adjusted in pH to 6-11 with an alkaline composition so taht alkaline hydrolysis as well as precipitation of organic material occurs and the treated effluent contains less AOX than present in the original untreated effluents; the AOX removal is enhanced substantially by (i) the presence of a sulphide or (ii) by carrying out the alkaline treatment at elevated temperature and pressure.

Dependencies are inferred from the claim text.