Recovery of Chromium and Two Solvents (Dichloromethane-DCM Tetrachloroethane-TCE) Using Nanofiltration and Reverse Osmosis Membranes from Leather Industry Wastewater

Abstract

In this study, for removal of the leather industry pollutants and to recovery of chromium (Cr), dichloromethane (DCM) and tetrachloroethane (TCE) two sequential nanofiltration (NF) (NF90 and NF270) and two reverse osmosis (RO) (BW30 and SW30) reactor membranes were used. The membrane surface properties were investigated by Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance (FTIR-ATR) and Scanning Electron Microscopy (SEM). The permeate of the SW30 reverse osmosis exhibited high removals varying between 98% and 99% for sodium ion (Na+ ), potassium ion (K+ ), magnesium ions (Mg2+), calcium ions (Ca2+), total chemical oxygen demand (CODtotal), dissolved chemical oxygen demand (CODdis), dissolved organic carbon (DOC) and inert chemical oxygen demand (inert COD), Chromium (Cr3+ ), Dichloromethane and Tetrachloroethane. In the NF90 nanofiltration process lower removals were detected (96%-97%) for all pollutants mentioned above. The effluent of reverse osmosis with a BW30 membrane match to the Turkish Water Pollution Control Regulation rules for treated water discharged to the receiving environment while SW30 reverse osmosis membrane was perfect for ultimate treatment of the pollutants present in the leather industry discharges. From the concentrate of the SW30 reverse osmosis, 945 mg/l chromium, 460 mg/l dichloromethane and 360 mg/l tetrachloroethane were reused. The performance and recoveries of Cr and two solvents (DCM and TCE) data in NF and RO membrane reactors were evaluated with Artificial Neural Network (ANN) process and Kruskal Wallis test statistic coupled with Mann-Whitney U statistic in this study.