Toray develops RO membrane that saves water and halves replacement   

Integrated chemical industry group Toray Industries has developed a durable reverse osmosis (RO) membrane, which offers long-term provision of high-quality water. It also maintains the removal performance of its existing membranes for reusing industrial wastewater and treating sewage.

The new membrane is said to double the resistance to cleaning chemicals of conventional counterparts. This reduces performance degradation from membrane wear and simplifies operational management, halving replacement frequencies and shrinking the product’s carbon footprint.

The company is preparing to mass produce this membrane and launch it in the expanding Chinese market in H1 2024. It looks to develop products with the new membrane for the global market including Japan.

The broad applications of RO membranes include desalinating seawater and river water, reusing wastewater, and producing drinking water as a technology to ensure sustainable water sources. Reusing wastewater entails treating water of diverse quality levels with RO membranes. The downside is that an increased reliance on cleaning chemicals to purge contaminants on the membrane surface to maintain their operational efficiency deforms their pores, diminishing removal performance. This has spurred demand for more resilient membranes.

The company combined a Toray Research Centre-developed scanning transmission electron microscopy technology and a digital data analysis technique to quantitatively analyse the pore of the separation layer of RO membranes, which is smaller than one nanometre in diameter. Toray drew on the analysis to identify a substructure that helps enhance pore structure stability when in contact with cleaning chemicals. It innovated a manufacturing process to design a new polymer structure, thus creating a RO membrane that delivers a stable pore structure.

Toray tested its new RO membrane at a wastewater reuse plant to simulate harsh chemical cleaning conditions. The membrane proved effective in reducing deterioration in the quality of obtained water. This membrane should deliver an extended lifespan in such applications in sewage treatment and wastewater reuse facilities of chemical, steel, and dyeing plants requiring frequent chemical cleaning and in attaining zero liquid discharge (ZLD). This could potentially slash CO2 emissions by half, associated with replacing and disposing of membranes. Toray will then establish a mass production system to supply products meeting customer needs.

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