Biofouling problems in membrane processes for water desalination and reuse in Saudi Arabia

Saudi Arabia is a fast growing country with limited drinking water supplies. Its water consumption is expected to reach 20 billion m3 annually by the year 2000. Most of this water is required for agricultural, industrial and domestic purposes. In order to meet these large water demands, about one-third of the world capacity of water desalination is produced in Saudi Arabia. Two main technologies are currently used in the Kingdom for water desalination, these are the Multistage Flash method (MSF) and the Reverse Osmosis membrane (RO) process. It is worth mentioning that MSF plants are suffering mainly from scale and corrosion problems, whereas the RO membrane processes are actually suffering from fouling, biofouling and biocorrosion. Hence, attention in the present work is given to this harmful degradation phenomenon of membrane processes known as biofouling, especially for the water desalination and waste water treatment because of their significant importance to the water sector in Saudi Arabia. The biofouling tendency of various water streams (specially Gulf water) is discussed in order to account for its dependence on water quality and membrane module applied. The various mechanisms of biofouling and corrosion induced by biofouling are given in view of the microbiology of the water processes and the membranes used. Some selected case studies from Saudi Arabia, in which the biofouling problems played the main role in reducing the actual performance of the membrane process, are also described and discussed.