Evaluation of the performance of polymeric coagulants and flocculants on the characteristics of paper mill effluent

Due to the high pollutant load of paper mill effluent and in order to decrease contaminants, effluent should be treated before being discharged into the environment.

After collecting samples of paper mill effluent in Babol city, high levels of COD and TSS were found. Therefore, polymeric coagulants such as iron sulfate, ferric chloride, polyaluminum chloride, and alum were employed, as well as anionic and cationic polyacrylamide flocculants.

Ferrous sulfate, ferric chloride, aluminum polychloride and alum at their optimum pH removed 12%, 13.5%, 15%, and 23% of effluent COD, respectively, as well as 45.5%, 47%, 49% and 52% of TSS. Then, by examining the coagulants concentration effect, alum with an optimal concentration of 1 g/l removed 23.7% COD and 56.4% TSS. Additionally, the effects of anionic and cationic polymeric coagulants were studied. According to the results, using an anionic coagulant at a concentration of 0.004 g / l in combination with the optimal amount of alum resulted in the elimination of 48.6 % COD and 69.6 % TSS.

Based on the results, the coagulation and sedimentation methods can be utilized to treat the effluent of paper mills. Furthermore, using an alum coagulant and an anionic coagulant at the same time improves the efficiency of the coagulation and flocculation processes in removing pollutants from paper mill effluent.