APPLICATION OF FERROUS-HYDROGEN PEROXIDE FOR THE TREATMENT OF H-ACID MANUFACTURING PROCESS WASTE-WATER

1-Amino-8-naphthol-3,6-disulfonic acid (H-acid) is widely used in chem ical industries for synthesis of direct, acid, reactive and azoic dye. The wastewater from H-acid manufacturing process is rich in various s ubstituted derivatives of naphthalene and is one of the most hardly-tr eated wastewaters. A pretreatment method, ferrous ion-peroxide oxidati on combined with coagulation, has been studied. The results have shown that the optimum pH value is below 4 and the suitable ferrous ion dos age is 200 mg/l. The COD removal of H-acid wastewater is about 50% and the residue have proved biodegradable when hydrogen peroxide dosage i s 30 g/l. Ferrous ion-peroxide oxidation process can also improve effi ciency of coagulation treatment. The overall COD removal can reach 90% or more when the concentration of ferrous ion is 200 mg/l, the dosage of hydrogen peroxide is 3 g/l and the ferric chloride dosage of two s tage coagulation treatment is 15 g/l and 5 g/l, respectively. The grou ps on naphthalene ring, such as - + NO2, SO3- etc., are substituted by hydroxyl free radical, and then the ring is broken down during oxidat ion process of H-acid. Copyright (C) 1996 Elsevier Science Ltd