The Water Blog - by Nice Water UAE

              pic: damaged membranes due to silica fouling Silicon is the element which is the second most abundant in the crust of the earth by mass. Therefore, natural water sources usually contain a certain level of silica, from 1 to 40 mg/L. In some geographic areas, its concentration can reach up nearly to 100 mg/L. As RO operation proceeds, the silica level in the concentrate stream increases and often reaches saturation, which can cause deposits of silica, or precipitation of metal silicates on the membrane surface (Scaling). Silica fouling is very difficult to remove from RO membrane, and eventually leads to performance deterioration such as permeability loss and premature system shutdown. Occurrence The potential of silica scaling occurs when the dissolved silica level in an RO system concentrate (i.e., reject stream) exceeds the solubility limit (≈ 120 to 150 mg/L at ambient temperature) for amorphous silica. Exceeding this saturation level in cold water (< 10°C) is not as