Bidirectionally-flowing nanofiltration membrane water treatment system and method

Abstract

The invention provides a bidirectionally-flowing nanofiltration membrane water treatment system and method. The system comprises a water tank, a membrane component and a valve component, wherein the water tank is connected with the membrane component through the valve component; the membrane component comprises a component main body and a convergence pipeline, the component main body is formed by arranging multiple membrane elements in parallel, a water inlet pipeline and a water concentrating pipeline are arranged at the two ends of the membrane elements respectively; the valve component is communicated with the convergence pipeline. According to the bidirectionally-flowing nanofiltration membrane water treatment system, a bidirectionally-flowing mode is adopted for conducting nanofiltration membrane water treatment in an alternate mode, and the pollution resistance of the nanofiltration membrane elements is improved.

Description

technical field [0001] The invention relates to nanofiltration membrane treatment technology, in particular to a bidirectional flow nanofiltration membrane water treatment system and method. Background technique [0002] The principle of reverse osmosis (RO) technology is that the raw water passes through the reverse osmosis membrane under the action of high pressure, and the solvent in the water diffuses from high concentration to low concentration to achieve the purpose of separation, purification and concentration. Nanofiltration technology is a membrane separation technology separated from reverse osmosis technology, which belongs to the continuation and development branch of low-pressure reverse osmosis technology. [0003] Nanofiltration membrane has the following three salient features: [0004] 1) The molecular weight cut-off is 150-2000 (between reverse osmosis membrane and ultrafiltration membrane); [0005] 2) It has a certain rejection rate for inorganic salts ...

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Problems solved by technology

[0008] However, nanofiltration membrane treatment technology generally has disadvantages such as high operating costs (the main operating cost is the power consumption of the high-pressure pump), and the nanofiltration membrane is easy to pollute; and the traditional nanofiltration process basically adopts a multi-stage series connection method. Obviously, the higher the recovery rate, the higher the recovery rate. The more membrane elements need to be connected in series, and when multi-stage nanofiltration membrane elements are arranged, the concentrated water of the previous stage is used as the feed water of the next stage, because part of the feed water of each stage nanofiltration membrane element becomes product water , so the influent flow of each section from the front to the back will decrease in turn, and the salt content will gradually increase, so in order to ensure the normal influent flow, the number of membrane elements in the next section should be less than the number of membrane elements in the previous section

[0009] In addition, there is a certain pressure loss when the raw water passes through each membrane element. In order to overcome the corresponding pressure loss generated by each membrane element, the traditional nanofiltration process requires a relatively large inlet pressure, which increases the operating time accordingly. power consumption; and because the concentration of water entering the next membrane element will gradually increase, under the premise of the same membrane treatment level, the water production of the membrane element will decrease in turn; and because the concentration of water entering each membrane element and Different water inlet pressures will increase the degree of contamination of the membrane element as a whole

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