Sequential treatment of paper mill effluent with modified Fenton oxidation and bioflocculation

Abstract

Pollutants emerging from the effluents of paper mills eventually destroy the environment of our ecosystem. To find a proper solution of it, a cost-effective and environmentally benign technique is proposed here to remediate contaminants present in the effluent of paper mill in a sequential steps using advanced oxidation processes including Fenton reaction (FO) (Fe(II)/H2O2), modified Fenton oxidation (MFO) (Fe(II)/Zn(II)/H2O2) and biological flocculation process. A comparison and compilation among these techniques were carried out on the basis of the percentage removal of chemical oxygen demand (COD) as well as the observed degradation pattern in gas chromatography–mass spectrometry. Results revealed that MFO could remove ≥ 90% of COD at ~ 90 min, whereas FO could eliminate ≥ 80% COD at ~ 120 min. Further, the bioflocculation technique was found to reduce the heavy metal contents such as Fe, Mn, Zn, Co, Cd and Pb by ≥ 60%. In the sequential treatment process, lignin, phenolic and colour contents were also found to be reduced by ~ 84% ~ 97% and ~ 96%, respectively. Again, the bioassay tests were performed to verify the toxicity reduction in the industrial effluent after the application of the sequential treatment process. This study demonstrates that the sequential treatment technique could be an effective alternative for the treatment of paper mill effluent.