Preparation of inorganic compound coagulant and its application in the treatment of dyeing effluent

A new type of inorganic polymer coagulant polysilicate aluminium ferric(PSAF) was prepared from coal gangue and pyrite slag and used as coagulant in the treatment of dyeing effluent,aiming at improving the treatment effect of dyeing effluent with coagulant.The experimental results showed that PSAF had a good coagulation effect in the treatment of dyeing effluent under the pH value ranging from 6 to 9.The removal rate of SS,colority and COD_(cr) was 94.1%,88.6% and 81.2% respectively under such conditions as room temperature,pH value=7.2 and dosage of the coagulant(75 mg/L.) In comparison with the conventional coagulants,such as PAC(polyaluminium chloride) and PFS(polyferric sulfate),the coagulation performance of PSAF is characterized by higher settlement rate,smaller sludge volume,lower remains of pollutants in the treated dyeing effluent and lower cost of treatment.