Atomic layer deposition of an ultrathin alumina coating boosts RO membrane ozone tolerance by 5x, enabling ozone cleaning without chemical degradation. Read the 2026 breakthrough from Environmental Science & Technology.
Biofouling is one of the biggest operational headaches in reverse osmosis (RO) desalination. It clogs membranes, raises energy demand by 20–50%, and forces frequent chemical cleanings that generate secondary pollution. Ozone disinfection – a highly effective, chlorine‑free biocide – would be an ideal solution to control biofilm growth. There is one problem: ozone is highly oxidative. Even at very low doses, ozone rapidly degrades the polyamide (PA) active layer of standard thin‑film composite RO membranes, causing irreversible loss of salt rejection.
Now, a research team from the Weizmann Institute of Science and Ben‑Gurion University has solved this “ozone‑disinfection vs. membrane‑oxidation” dilemma using atomic layer deposition (ALD). By depositing an ultrathin, just 3 nm thick alumina nanocoating on a commercial ESPA‑PA RO membrane surface, the researchers created a protective layer that provides both active and passive defense against oxidative damage.
The results, published in Environmental Science & Technology in January 2026, are striking. The alumina‑coated membrane demonstrated 5‑fold higher tolerance to ozone exposure than uncoated membranes. Under an ozone dose of 5.5 mg·h/L, the coated membrane maintained 96% salt rejection and stable water flux, while the uncoated membrane‘s rejection plummeted to just 60%. In a 48‑hour continuous ozone exposure test, the ALD‑coated membrane completely suppressed biofilm formation – the uncoated membrane lost 45% of its flux due to biofouling.
This breakthrough means that for the first time, RO plant operators can use ozone as a routine cleaning agent without sacrificing membrane life. The alumina nanocoating also prevented biofilm formation effectively and maintained stable performance after prolonged filtration-2. The technology is industrially scalable, as ALD can be performed at low temperatures (<50 °C), preserving the delicate PA structure beneath.
For the water industry, this is a game‑changer. Ozone cleaning reduces chemical consumption, eliminates chlorine‑related disinfection byproducts, and lowers overall operational costs. With ALD‑alumina RO membranes, durable, sustainable desalination is finally within reach.
