Biofouling control in reverse osmosis membranes for water treatment

Identifier:  TDX:2722

Handle: https://hdl.handle.net/20.500.11797/TDX2722

Authors:  Massons Gassol, Gerard

Abstract:
Reverses osmosis (RO) filtration is one of the most competitive water purification technologies. RO systems have evolved significantly in the last years to provide real and sustainable solutions to water-related problems. One of the main hurdles that hinders RO expansion in water reuse, is the loss of performance that RO elements suffer when dealing with contaminated waters. This phenomenon known as fouling, remains to be one of the biggest challenges for RO elements used in industrial or wastewater treatment plants. Due to the complexity to study these problems in large scale systems, protocols need to be developed in order to mimic full-scale plants operation on a bench scale. Fouling problems are usually occurring after several month of operations. However, for a realistic time-scale research, the process needs to be accelerated in a controlled way and as similar as possible to what would be occurring naturally. The effect of different operating variables on biofouling development was studied. The role of RO module construction was also evaluated, testing different membranes and feed spacers side-by-side, to guide the improvements on the design of fouling resistant elements. The results from the trials performed clearly showed that different membrane chemistries can provide significant reduction in the levels of biofouling detected after operation. However, it was found that the main contributor to biofilm development was feed spacer. Large differences in the amount of biofouling generated could be associated with feed spacer presence. Feed spacer design was then studied in detail to achieve a balanced performance in spiral wound RO modules treating waters prone to biofouling. Feed spacers with various thickness, spacing and angle were tested and some designs showed advantages in pressure drops, as well as on biologic and organic fouling accumulation.