Reverse Osmosis (RO) is the dominant membrane technology used for seawater desalination. However, seawater contains varying concentrations of constituents commonly known as foulants such as fine colloidal particles and organics that may clog/foul the membranes. Climate change effects have also led to more frequent and intense algal bloom events. These collectively would promote fouling tendency on the RO membranes. Consequently, the process would require higher energy and more frequent membrane cleaning to maintain its operation.

Pre-treatment plays a critical role in minimising foulants and to provide consistent feed water quality to the RO process even under occasions of high fluctuating seawater quality intake for the desalination process.

NERI has embarked on projects to develop low-chemical-energy pre-treatment processes in seawater desalination. Innovations of the projects involved the development of a robust, integrated and cost-effective electrocoagulation (EC) pre-treatment platform, and process optimisation of new ceramic ultrafiltration membrane for seawater desalination.

Electrocoagulation (EC), which involves the passage of electricity through sacrificial aluminium/iron electrodes immersed in the liquid to be treated. The dissolving metal combines with hydroxide ions generated to form a similar coagulant floc, and gas bubbles aid in coagulant separation from the treated water. Preliminary cost analyses showed that EC has the potential to reduce the operating cost by half compared with the typical pre-treatment process (comprised the chemical coagulation with dissolved air flotation with ultrafiltration (UF) membrane process) applied in seawater desalination.

UF process in the pre-treatment removes fine particulate matters prior to the RO process. Ceramic UF membranes have shown to be more robust and resistant to fouling compared with the polymeric counterparts. Thus, ceramic membrane could be operated with lower membrane cleaning frequency. This offers the potential of lower chemical and energy costs in its operation.

The R&D is conducted in collaboration with industrial partners which would bring the technology and process for commercial application following successful test-bedding and validation at pilot scale. The outcome of the studies would innovate the approach in seawater desalination providing more sustainable and cost-effective treatment, while enhancing resilience of the desalination process toward climate change effects.