Processing of biscuit industrial effluent using thin film composite nanofiltration membranes

Abstract

Nanofiltration (NF) is a membrane-based separation process having significant potential for the treatment of industrial effluents to enable water reuse. It has the ability to remove low molecular weight trace contaminants from water, which cannot be separated by conventional treatment methods. In the present investigation, a thin film composite polyamide membrane was synthesized by interfacial polymerization technique and evaluated for the treatment of biscuit industrial effluent. The synthesized membrane was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy to elucidate structure and intermolecular interactions, crystallinity, thermal stability and cross-sectional morphology, respectively. The influence of operating parameters such as feed pressure 0-21 kg/cm2 and total dissolved solids (TDS) of 3160 ppm on water flux and impurity rejection was determined. An average flux of 11.63 L/m2 h was obtained at a constant pressure of 21 kg/cm2. The TDS, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) rejections were found to be 53.62, 80, and 74%, respectively, at a water recovery of 65%. A statistical mechanical model was used to validate the experimental data. Based on this study, a detailed economic estimation for processing biscuit effluent of 1 m3/h feed capacity using commercial NF system is presented. The study revealed that the synthesized NF membrane could be an effective alternative for the treatment of various industrial effluents as well as to reduce the load on reverse osmosis process for desalination of seawater and effluent treatment through high degree of COD and BOD separation.