Optimising low-pressure membrane pre-treatment for desalination

Low-pressure porous membranes are increasingly considered for pre-treatment of sea and brackish waters. However, membrane fouling remains a major drawback, as it results in higher operating, maintenance and cleaning costs. Through the development and validation of techniques for advanced characterisation of the organic compounds present in feedwaters, this project aims to better understand and to optimise the strategies currently used for fouling control. The relative efficiencies of both physical (relaxation, backwashing) and chemical cleanings will be assessed on lab and pilot scales. The organic and inorganic nature of the irreversible fouling formed during long-term filtrations (and repeated cleanings) will be characterised in detail, allowing recommendations for sustainable operation and performance.

Moreover, the impact of the presence of algae in seawater on pre-treatment membranes will also be investigated. Not only the algae itself is expected to significantly affect the performance of the low-pressure membranes, but physical and chemical stresses on algae could also be responsible for the release of organic compounds with high fouling potential. In addition, some of those released extra-polymeric substances are expected to permeate through the pre-treatment and have a significant impact on the RO system. It is therefore crucial to understand and characterise the link between algae, physical and chemical stress and performance of the dual membrane systems used for desalination.