Hybrid forward osmosis-reverse osmosis for wastewater reuse and seawater desalination: Understanding the optimal feed solution to minimise fouling

Abstract

To enhance the seawater desalination energy efficiency forward osmosis-reverse osmosis (FO-RO) hybrid system has recently been developed. In this process, the FO "pre-treatment" step is designed to dilute the seawater (SW) with reclaimed wastewater (WW) before the desalination step, thereby reducing the energy demand for the SWRO process. However, membrane fouling is a major issue that needs to be addressed. Proper selection of suitable WWs is necessary before proceeding with largescale FO-RO desalination plants. In this study, long-term experiments were carried out, using state-ofthe-art FO membrane with real WW solutions. A combination of water flux modelling and membrane characterisation were used to fouling to process performance. Initial water fluxes as high as 22.5 L.m-2 .h-1 were observed when using biologically treated secondary effluent. It was also found that secondary effluents cause negligible flux decline. On the other hand, biologically treated wastewater and raw wastewater caused mild and severe flux decline respectively (25% and 50% of flux decline after 80 hrs, compared to no-fouling conditions). Ammonia leakage to the diluted seawater was also measured, concluding that, if biologically treated wastewater is used as feed, the final NH 4 + concentration in the draw is likely to be negligible.

A Bibliometric and Visualized Overview for the Evolution of Process Safety and Environmental Protection

“…In addition, a few new research topics emerge in this period, such as catalytic degradation of organics (especially utilizing a microbial community) [ 171 , 172 ], application of ionic liquids [ 173 ], degradation and toxicity analysis [ 174 , 175 ], the application of microwave for waste treatment [ 176 , 177 ], safety of drinking water and its treatment [ 178 ], mineralization technology for pollutant emission control [ 179 ], Industry 4.0 [ 180 , 181 , 182 ], mine fires and CSC prevention [ 183 , 184 ], air leakage measurement and sealing techniques [ 185 , 186 ], risk analysis and prevention considering synergistic effects and domino effects [ 187 , 188 ], etc. It is obvious that scholars pay more attention to advanced techniques, as well as traditional methods, to conduct real-world industrial problems, for instance, catalytic ozonation [ 189 ], forward osmosis [ 190 ], photocatalytic [ 191 ], electro-oxidation [ 191 ], biochar adsorption [ 192 ], artificial neural networks [ 193 ], genetic algorithm [ 194 ], (global) sensitivity analyses [ 195 , 196 ], process optimization method (e.g., RSM, CCD) [ 197 , 198 ], bowtie analysis [ 199 ], fuzzy AHP [ 200 , 201 ], dynamic BN [ 187 , 202 ], etc., for environment protection and process safety and risk analysis.…”

Breakthroughs in the fabrication of electrospun-nanofiber-supported thin film composite/nanocomposite membranes for the forward osmosis process: A review

“…It is worth mentioning that, the thickness of CA is half of the TFC membrane (100 μm vs 50 μm) (Ren & McCutcheon, 2014). Also, a commercial TFC-FO with S value of 266 µm was produced by Oasys Water Inc. (Boston, MA) (McGinnis, Hancock, Nowosielski-Slepowron, & McGurgan, 2013), while Toray Industries, Korea, successfully fabricated a commercial TFC-FO flat-sheet membrane with S value of 409 µm (Volpin et al, 2018), and spiral wound TFC-FO membranes labeled as 8′′SW and 8040 SW with very high A values of 8.9 and 5.54 LMH/bar, respectively, but no information was provided about the S values (Kim, Phuntsho, et al, 2018;Kim et al, 2017). Also, Porifera (Porifera, Hayward, CA, USA) and Aquaporin A/S (Aquaporin A/S, Copenhagen, Denamark) provided the commercial TFC-FO membranes with S values of 269 and 301 µm, respectively, Xie et al, 2018).…”

Critical flux-based membrane fouling control of forward osmosis: Behavior, sustainability, and reversibility

“…Forward Osmosis (FO) is an osmotically driven membrane process in which water is transported from low osmotic pressure (feed solution) to high osmotic pressure (draw solution) across the semipermeable membrane through the action of a chemical potential gradient [1]. Hybrid FO processes have recently emerged as possible systems for the simultaneous treatment of impaired/reclaimed water and seawater for reuse [2] [3] [4] [5] since standalone FO process cannot economically achieve either water treatment or desalination of seawater. These hybrid processes can bring many advantages regarding the energy consumption and the water quality: i) decrease of desalinated energy cost because seawater is diluted before entering RO desalination, ii) reduction of the fouling propensity of the RO stage through pretreatment of impaired water; (iii) a multibarrier protection is established to improve contaminant removal; thereby giving opportunity for safe and high-quality reuse of impaired water [5] [6] [7].…”

“…Hybrid FO processes have recently emerged as possible systems for the simultaneous treatment of impaired/reclaimed water and seawater for reuse [2] [3] [4] [5] since standalone FO process cannot economically achieve either water treatment or desalination of seawater. These hybrid processes can bring many advantages regarding the energy consumption and the water quality: i) decrease of desalinated energy cost because seawater is diluted before entering RO desalination, ii) reduction of the fouling propensity of the RO stage through pretreatment of impaired water; (iii) a multibarrier protection is established to improve contaminant removal; thereby giving opportunity for safe and high-quality reuse of impaired water [5] [6] [7]. In detail, complex wastewater (i.e., raw sewage, primary effluent, secondary effluent, biologically treated wastewater effluent) can be directly pre-treated by FO process (i.e., pre-treated wastewater or pre-concentrated wastewater) and subsequently potable water can be produced by combining with a draw solute recovery process (i.e., reverse osmosis or membrane distillation) [8] [9].…”