The Evaluation of the Performance of Polymeric Coagulants and Flocculants on the Characteristics of Paper Mill Effluent

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Alireza Seify, Majid Peyravi, Mehri Esfahanian, Hassan Ahmadi


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

Materials and Methods: After collecting the samples of paper mill effluent in Babol city, the high levels of COD [Chemical Oxygen Demand] and TSS [Total Suspended Solids] 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.

Results: Ferrous sulfate, ferric chloride, aluminum polychloride, and alum at their optimum pH removed 12%, 13.5%, 15%, and 23% of the 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. Moreover, the effects of anionic and cationic polymeric coagulants were studied. Considering the results, using an anionic coagulant at a concentration of 0.004 g/l in combination with the optimal amount of alum resulted in eliminating 48.6% COD and 69.6% TSS.

Conclusion: Based on the results, coagulation and sedimentation methods can be utilized to treat the effluent of paper mills. Furthermore, using an alum coagulant and an anionic coagulant simultaneously improves the efficiency of the coagulation and flocculation processes to remove the pollutants from paper mill effluent.

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