ABSTRACT
All of the raw water in the world has micro-organisms such as bacteria, algae, funguses, and so on. These micro-organisms can be considered as colloidal materials and separated and removed by pre-treatment.Of course, the removal of all micro-organisms by the pre-treatment operation is very difficult, and some of them may escape from the pre-treatment process to reproduce and formed biofilm films.Microfiltration membranes (MF) and Reverse Osmosis Membranes (RO) can prevent many micro-organisms. However, some micro-organisms escape through the pores of the membrane and reach the reverse osmosis membrane, which can cause biological fouling in the membrane. The signs of reverse osmosis membrane fouling include the increase in differential pressure and the melt fluxIt should be noted that the potential of biological fouling in surface waters is much higher than that of wells water; the concentration of bacteria in water is also directly related to the potential for biological fouling. In this study, the causes of fouling of MF and RO membranes have been investigated and ways of preventing it have been presented
