Piloting Study on Biofouling Control of Reverse Osmosis System in Steel Mill Wastewater Reuse

Abstract

Abstract:The biofouling of RO (Reverse Osmosis) system is one of the most common problems in highly contaminated demineralization and wastewater reuse system. The biological fouling occurs due to the bacteria growth and proliferation under nutritive environment, resulting in a dramatic increase of dP (differential pressure) in the RO system, which requires frequent system shutdown for cleaning. This paper discusses the effectiveness of low-dP RO element and periodic flushing on the biofouling scheme of industrial steel mill wastewater reuse system. The low-dP RO element is able to provide low RO system dP, which is expressed to be lower biofouling starting point during the industrial system operation. However, the periodic flushing utilizes fresh water to remove the biofilm deposit along with feed channel. The long term operation performance demonstrated strong caustic is effective in removing the biofilm and recovering RO system performance. It is experimentally validated that, in the case of a high biofouling environment, low-dP RO element and periodic flushing is able to extend the cleaning cycles by 36.6% and 11.4%, respectively. Meanwhile, a joint application of both methods is proven to improve the biofouling control and extend the cleaning cycle by 62.5%, as compared to standard RO technology.