Evaluation of Different Forward Osmosis Membrane Cleaning Strategies for Produced Water Streams Treatment

Talal Alamoudi
2021
Forward osmosis (FO) as a novel membrane separation technology has recently been investigated in various water treatment applications. The natural mass transfer process between two solutions driven by the osmotic pressure difference leads to many operational advantages in the FO process, such as low energy consumption and minimal fouling problems. It makes FO a feasible technology for the treatment of produced water (PW). Although previously, the treatment of PW using FO has been investigated,
more » ... smotic backwashing (OB) is not systematically examined for water flux recovery of the PW fouled FO membranes. Moreover, the cleaning of FO membranes used for the simultaneous treatment of different PW streams was never previously attempted. In this study, OB was thoroughly investigated for the cleaning of PW-fouled FO membranes. Also, FO membrane chemical cleaning using SDS and NaOH solutions was examined too. To investigate OB, the cleaning efficiency of a 60 min OB cleaning protocol was examined under different FO operating modes in (5 x 20 h) experiments using synthetic desalter effluent as FO feed solution (FS) and 1.2 M NaCl solution or water-oil separator outlet (WO) as draw solutions (DS). The AL-FS (active layer facing FS) mode outcompeted the AL-DS (active layer facing DS) mode, achieving a flux of 12.9 LMH and 80.1% water reclamation when using WO as a DS. Therefore, this FO configuration 5 was selected when evaluating the cleaning protocols. Moreover, after evaluating different OB methods, the 30 min OB protocol achieved the highest system efficiency rate of 95% and was studied for the treatment of real PW streams. The SDS and NaOH chemical cleaning methods achieved flux recovery rates of 99% and 98% by the end of the third treatment cycle, respectively, outperforming the 89% flux recovery rate of the optimized OB protocol. Although the investigated cleaning methods were able to restore the system performance, a substantial increase in RSF was observed due to mainly irreversible colloidal fouling. This study dem [...]
doi:10.25781/kaust-3z972 fatcat:lssxdth7gbdkjfjqe6blrm2ugm