(376ac) Effect of Pressure and Spacer Configuration on Assisted Reverse Osmosis Performance

Water supply crisis is a reality in many places and it became a problem also in Brazil, typically known as a water-abundant country. Lack of suitable public policies and harsh droughts led to agricultural and industrial water shortage in the past few years. In this scenario, liquid effluents are a potential water source mainly in Northeast and Southeast regions. Particularly, oil produced water is abundant in these regions, although it can contains high levels of contaminants and salt content. Aiming to apply an economical and suitable technology for desalinate high salinity streams, assisted reverse osmosis (ARO) has been proposed as a potential low-energy technology, mainly for effluents out of conventional reverse osmosis (RO) range. This process is very similar to RO, but it uses a sweep or draw solution to diminish osmotic pressure difference across the membrane. With this feature, the same hydraulic pressure for RO can lead to a greater flux in ARO, although it is usually necessary to recover the sweep solution with a conventional RO process. As it is a novel technology, there is a lack of studies on its real performance, mainly for sweep solution flow and spacer configuration. In this paper, the effect of feed hydraulic pressure and sweep solution spacer configuration were studied in an adapted plate-and-frame ARO module. Three commercial spacers were tested over feed pressures until 60 bar with a commercial seawater reverse osmosis membrane. Head loss was also measured for draw solution module path as a function of feed pressure and number of spacers. It was verified that spacer design has a strong influence on membrane deformation and consequently its salt rejection. These results are similar to those obtained in literature for pressure retarded osmosis (PRO) technology. Besides, the feed pressure increases the compaction of spacers, also increasing the head loss significantly. This could be a major issue for plate and frame ARO modules design and flow optimization.