The reverse osmosis element membrane is one of the commonly used filtering materials in water treatment, and it can also bring better practical effects of the ro membrane filter in the water treatment process. During the operation of the membrane system, some factors will harm the characteristics of the reverse osmosis element membrane at the same time.
1. The harm of total traffic
Under a certain pressure, when the water in and out decreases, the desalination rate and water production will decrease. It is hurt by two factors. On the one hand, when the pressure is constant, a decrease in the amount of water in and out will increase the concentration of the system, resulting in an increase in multiples. When the following water supply and drainage concentration values increase, the osmotic concentration will also increase relatively, thereby reducing the pushing pressure, resulting in a decrease in water production, and an increase in salt content will also reduce the salt rejection rate. On the other hand, reducing the amount of water in and out corresponds to the surface angular velocity of the film, and increasing the thickness and concentration of the surface layer on the surface of the film.
2. Recovery rate of reverse osmosis element membrane
Under a certain pressure, the recovery rate increases, the concentration polarization ratio of the membrane surface will gradually increase, the reasonable pressure decreases, and the salt rejection rate decreases. The limitation of the recovery rate of the membrane system will come from two levels. One is the hazard of osmotic concentration, and the other is also closely related to the same source of water. The recovery rate is increased. When the salt dissolved in the aqueous solution is saturated, the concentration of some salt and other substances will be deposited in the reaction. Permeating the surface of the stainless steel filter, the possibility of fouling will cause great damage to the characteristics of the membrane.
3. Temperature factors
When the temperature increases, the proportion of water will decrease and the diffusibility of water will increase. In the future, as the temperature rises, the amount of water produced will also increase. Under the same pressure, every time the temperature rises, the water production can increase by 3-4%. On the other hand, for different types of reverse osmosis element membrane, the adverse effect of temperature on the salt rejection rate will be very large. Generally speaking, the increase in temperature will reduce the salt rejection rate, which is due to the increase in temperature and the diffusion of salt.
4. Feed water concentration
Under a certain pressure, when the sewage concentration value increases, the water production will decrease, mainly because the osmotic concentration of the supplied water will increase, and the pressure will decrease when the pressure decreases. The desalination rate is directly affected by the concentration value. Generally, the concentration value increases, the amount of long water decreases, and the desalination rate decreases. But when the concentration is extremely low, the initial content increases, and the salt rejection rate also increases. Then, as the content continues to increase, the salt rejection rate will appear very low.
The increase in water production is positively correlated with pressure, because the salt passage speed is relatively less harmful to pressure. With the increase of water production, due to the use pressure, the salt rejection rate will also increase, which is roughly a certain value.