| The increase of wastewater is now a crucial problem involving with the petroleum industry. As the development of tertiary oil recovery technique, the previous techniques for water flooding of oily wastewater can not satisfy the requirement of more complicated oilfield wastewater treatment any more. It is indicated from the study that the membrane treatment technique can make the oil field produced water conform to the most rigorous water standard and it had been widely acknowledged as one of the best technique, i.e., developing the very material which maintains large membrane flux, perfect membrane quality and pollution resistance is one of the most potential treating ways. Therefore, new ion-exchange membranes based on organic material modified by the addition of inorganic nano-sized particles had been adopted in this paper, and a small self-invented electro dialysis instrument had been adopted to experiment the desalination of water produced from Daqin polymer flooding oilfield. Moreover, performance of modified membrane's desalination as well as the mechanics of membrane fouling and the technique of cleaning also had been investigated.Using a small self-invented electro dialysis instrument, the advanced treatment had been carried out for the oilfield wastewater, and meanwhile testing the performance of the modified PVDF ion-exchange membrane, which is used to decrease the oilfield wastewater salinity, and specifically discussing factors that influence the separation performance of ion-exchange membrane, including operation pressure, feed concentration, feed temperature as well as working time. Besides, the pollution analysis of modified ion-exchange membrane polluted by crude oil suspended matter and polymer also had been investigated. The conclusions are as follows. The desalination performance of modified ion-exchange membrane is much better than that of non-modified one. The limiting current density and the desalination rate for modified ion-exchange membrane are higher than that of the no-modified, and its dissipation energy is much lower. The optimal operating parameter for this modified PVDF ion-exchange membrane lists as follows:the working voltage is 8V and the concentrated and fresh water flow both equal 25L/h.It is shown from the experiment that this electro instrument can effectively eliminate the cationic and anion. The elimination efficiencies of the salt containing aqueous varies from ingredients, the average values are respectively as 94.9%,92.5% and 93.7 for the cationic, anion and the whole salt containing aqueous. The modified PVDF cationic-exchange membrane is less suffered from pollutants and the modified PVDF anion-exchange membrane is seriously polluted. The adsorption fouling plays a major part in the pollution and the modified membrane absorbs fewer pollutants than that of the non-modified. Based on the analysis of pollution mechanics for the membrane subjected to various pollutants, methods of polluted membrane cleaning had been proposed. The better cleaning methods of modified membranes fouling which is suffered from the suspended matter and crude oil are respectively as hydrochloric acid cleaning and alkaline-surfactant cleaning. By adopting the above mentioned cleaning methods, a chemical cleaning procedure had been carried out for the membrane fouling involving with the suspended matter, the crude oil and polymer, and it can effectively enhance the desalination rate of the PVDF ion-exchange membrane.
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