The pretreatment with enhanced coagulation and a UF membrane for seawater desalination with reverse osmosis

The application of reverse osmosis (RO) for desalination process has increased rapidly with the construction of large RO plants. Although there have been considerable improvements in membrane materials and operation experience, the fouling of membranes is a significant problem up to the present. There have been many instances of fouling of RO membranes caused by the presence of iron and silica. Biomineralization is usually believed to be caused by microorganisms metabolizing at iron and silica present. Its formation process was studied and described first in the present work, then the enhanced coagulation with Fe(VI) and UF membrane treatment process for pretreatment of reverse osmosis for desalination has been investigated in a laboratory for 3–4 months. The main aim is to reduce the feed water pollution, such as turbidity, iron, silica and aglae, microbial contamination in order to control biofouling and mineralization on the membrane surface. The results showed that the biomineralization formation process is the adsorption of organism and the biosorption of inorganics onto the organic matrix. The pretreatment results show that turbidity is less than 0.5 NTU, iron concentration never exceeds 0.2 mg/l, silicon concentration must not exceed 0.1 mg/l; and the removal rate of aglae and microbial is more than 98%.