Current Status and Future Trend of Dominant Commercial Reverse Osmosis Membranes

Since 2000, seawater reverse osmosis method has been a dominant desalination technology against the distillation method in the global market. The large project called “Mega-SWRO” (half mega-ton per day and larger) plant in the Middle East is quite popular making full use of the combination with solar energy. Today, the price of desalinated water is affordable at as low as $0.28/m3 to $0.53/m3. Likewise, dominant commercial reverse osmosis membrane is a cross-linked fully aromatic polyamide composite membrane-spiral wound element including FT-30 (DuPont Water Solution) and UTC-80 (Toray Industries., Inc., Otsu, Shiga, Japan). The said membranes are much superior in terms of performance compared to the cellulose triacetate membranes-hollow fiber for variety of applications including seawater desalinations, brackish water desalination, wastewater reuse, ultra-pure production for semiconductor, home-use water purifier, etc. SWCC of Saudi Arabia has announced that it intends to shift from cellulose triacetate hollow fiber to spiral wound RO membranes at all of its plants. Furthermore, the state-sponsored R&D on membrane and membrane process has been put into practice in major countries, including Japan and Korea, which contributed to the progress of membrane science and membrane process, suitable for spiral-wound polyamide membranes. SWCC has announced their plans for SWRO, mainly focusing on brine mining to obtain precious materials from the brine of SWRO. New and innovative brine-mining technology has been introduced for green desalination.

Advances and Applications of Hollow Fiber Nanofiltration Membranes: A Review

Hollow fiber nanofiltration (NF) membranes have gained increased attention in recent years, partly driven by the availability of alternatives to polyamide-based dense separation layers. Moreover, the global market for NF has been growing steadily in recent years and is expected to grow even faster. Compared to the traditional spiral-wound configuration, the hollow fiber geometry provides advantages such as low fouling tendencies and effective hydraulic cleaning possibilities. The alternatives to polyamide layers are typically chemically more stable and thus allow operation and cleaning at more extreme conditions. Therefore, these new NF membranes are of interest for use in a variety of applications. In this review, we provide an overview of the applications and emerging opportunities for these membranes. Next to municipal wastewater and drinking water processes, we have put special focus on industrial applications where hollow fiber NF membranes are employed under more strenuous conditions or used to recover specific resources or solutes.