Electro-coagulation of Bio-treated Pharmaceutical Wastewater for RO Pretreatment

Abstract

Background: The advanced wastewater and water treatment by Reverse Osmosis (RO) system have almost become a common treatment option in industries. However, achieving a consistent RO feed water quality and the rigor of RO pre-treatment pose a big challenge for water treatment specialists. Due to the RO critical limiting feed parameters (Silica, Turbidity, BOD, and Total hardness) and the inadequate consideration of the limiting feed parameters in the recycling plant design, the Reverse Plant likely fails due to scaling of membrane and poor productivity. This calls for judicious consideration of an appropriate pre-treatment technology in line with the feed water quality.
 Objective: The objective of the work was to study the electro-coagulation treatment of pharmaceutical wastewater with reference to critical RO feed parameters.
 Materials and Methods: In this paper, the Electro-coagulation (EC) treatment of Bio-treated pharmaceutical wastewater was explored as a Pre-treatment for the RO system. In the EC reactor of 1m3 working volume, bipolar sacrificial Iron electrodes were used, and RO Critical parameters were examined post electro-coagulation treatment.
 Results: Among the 14 RO critical parameters that was investigated, five parameters namely Aluminium as Al, Iron as Fe, Turbidity, Zinc as Zn, and Silica as SiO2 have registered a reduction range of 80 to 96 %, in the RO feed water after electro-coagulation. Four other parameters like Manganese as Mn, BOD, Phosphate as P, and Magnesium as Mg have shown a reduction range of 50 to 80%.
 This enables the plant to be operated at higher efficiency with increased RO recovery. The test parameters before and after the study were subjected to regression analysis and were found to have a statistical significance of one and P<0.01.
 Conclusion: EC pre-treatment is applicable for all types of RO (Disc & plate, conventional wound) membranes and enhances the life of the membrane by reducing membrane fouling, maintenance, chemical cleaning, and overall treatment cost.