Osmotic cleaning of typical inorganic and organic foulants on reverse osmosis membrane for textile printing and dyeing wastewater treatment

Abstract

Reverse osmosis (RO) is one of the most fundamental membrane technology because it has higher salt rejections, which suffers from the issue of membrane fouling, as the membrane is inevitably exposed to foulants during the filtration process. For different fouling mechanisms of RO membrane, physical and chemical cleaning are widely used in the control of RO membrane fouling. The present study investigated the performance and water flux recovery using osmotic cleaning to clean the typical inorganic and organic foulants on RO membrane for textile printing and dyeing wastewater treatment. The effects of operation conditions (i.e., the concentration of cleaning solution, the filtrating time and cleaning time, and the flow rate of cleaning solution) on relative water flux recovery were examined. The results show that a highly water flux recovery (98.3% for cleaning of inorganic fouling and 99.6% for cleaning of organic fouling) was achieved under optimal operation of the concentration and flow rate of cleaning solution and the filtrating and cleaning time. Moreover, the experiment of repeated "filtrating-cleaning" cycles indicated that the osmotic cleaning has highly performance of recoverability of water flux (over 95.0%) can be extended in a relatively long time. The experimental results and changes on SEM and AFM images of RO membrane confirmed the successful development and application of osmotic cleaning for inorganic and organic fouling of RO membrane.

Keywords: Membrane fouling; Membrane separation; Osmotic cleaning; Reverse osmosis; Water flux recovery.