Performance Investigation of Pilot Study for Wastewater Reclamation Using Ferric Chloride as Coagulant

Abstract

A pilot study was conducted to evaluate the efficiency of ferric chloride as coagulant agent on the long term performance to reverse osmosis membrane technology. The pilot unit comprised of 50m³/day pore controllable fiber (PCF) technology as a pre-treatment prior to RO for water reclamation from an effluent treatment plant based in Malaysia. The additions of ferric chloride ahead of PCF unit give high rejection of permeate quality after RO such as TSS, COD, alkalinity, and nitrite. However, there is deterioration of RO membrane performance after the pilot unit has been run continuously for 24 hours over 3 months. Average percentage reduction for parameters such as BOD₅, COD, TDS, conductivity, and TSS for PCF-RO over 3 months operation is 51.12%, 70.01%, 68.36%, 68.39% and 69.17% respectively. Fouled RO membranes for both lines were analyzed using Fourier transform infrared (FTIR) spectroscopy and EDS coupled with scanning electron microscopy (SEM). EDS-SEM results showed that the foulants deposit on RO membrane for PCF-RO about 4.29-6.23µm and Fe element at 14.81% by the mean of weight. These imply that ferric chloride residual contribute to RO membrane fouling and thus affect the system stability and efficiency.