Flow-electrode capacitive deionization (FCDI) with microfiltration membranes for water reclamation from highly saline and dye-polluted wastewater

Abstract

Textile wastewater, in addition to being highly polluted by organics like dyes, contains large amounts of salts, e.g., ≈10gL−1, that need to be removed before discharged to the environment or reused. This work introduces a new FCDI process that uses microfiltration membranes to desalinate and decolor synthetic textile wastewater. Synthetic wastewater simulates the characteristics of real Indian textile wastewater, containing a mixture of different salts (NaCl, Na2SO4, NaHCO3), with a total concentration of 6.9gL−1, and tartrazine (MW =534.3gmol−1) as the large organic pollutant model, with a concentration of 2.1gL−1. FCDI modules with different membrane configurations, including microfiltration membranes (MF), are investigated, giving insights into the desalination and dye removal efficiencies under steady-state operation. At wastewater flow rates below 0.08mLmin−1, the conductivity of treated water reaches 0.2mScm−1, with a tartrazine concentration below 50mgL−1, fulfilling the requirement for water reuse in textile industries. This work reveals the potential of the FCDI process for both desalination and organics removal that can be applied to a wide range of wastewater streams.