Reverse osmosis strong brine concentration method and equipment

Abstract

The invention discloses a reverse osmosis strong brine concentration method and equipment. The concentration method comprises the following processes of (1) a positive osmosis concentration process: using reverse osmosis strong brine as raw material liquid, so that the water in the raw material liquid passes through a positive osmosis film to enter the liquid suction side through the effect of suction liquid, salt in the raw material liquid is intercepted at the raw material liquid side, and the raw material liquid can be concentrated; (2) a film distillation concentration process: conveying the raw material liquid concentrated in the step (1) to a hot side of a film distillation film; performing cooling by circulation water at the cold side of the film distillation film or vacuum suction,so that the water at the hot side passes through the film distillation film in a water vapor form to enter the cold side, the raw material liquid at the hot side loses water, and the raw material liquid is further concentrated. The concentration equipment comprises a positive osmosis device, a film distillation device and a strong brine tank. According to the concentration method and equipment, the positive osmosis is used as the film distillation pretreatment technology to perform deep concentration on the reverse osmosis strong brine, so that the whole energy consumption is reduced; the treatment of the reverse osmosis strong brine and the subsequent resource utilization are realized at low energy consumption and high concentration efficiency.

Description

technical field [0001] The invention belongs to the field of waste water treatment. Specifically, it relates to a method and equipment for concentrating reverse osmosis concentrated brine. Background technique [0002] Since the breakthrough of reverse osmosis technology in the 1960s, it has been widely used in the desalination industry, which has largely alleviated the shortage of fresh water resources. However, based on the concentration principle of the reverse osmosis process, it will produce a quarter of the by-products per unit volume of seawater it treats—reverse osmosis concentrated brine, with a salt content as high as 60,000mg / L-80,000mg / L. Including Cl - 、Na + , Ca 2+ , Mg 2+ 、K + and other inorganic ions. If the concentrated brine is directly discharged into the environment, it will pollute the water body and endanger the organisms in the water body. Moreover, salt is also a resource, and direct discharge also causes a waste of resources. Therefore, how ...

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Problems solved by technology

[0004] Considering the high salinity characteristics of reverse osmosis concentrated brine, the concentration technology used has the following technical problems: (1) For the evaporation pond technology, the evaporation concentration occupies a large area, has high requirements on light and climate conditions, and has a long concentration cycle, which greatly reduces It improves its concentration efficiency and economic benefits, and the concentration of reverse osmosis concentrated brine is low

(2) Due to the large number of heat exchanges, the multi-effect evaporation technology causes heat loss and increases the treatment cost; it is suitable for concentrated treatment of sewage and wastewater with medium salinity, and its equipment system is more complicated

(3) Evaporation and concentration technologies such as mechanical compression and re-evaporation, as an upgraded version of multi-effect evaporation, have indeed solved some of the problems of multi-effect evaporation, but there are still problems such as large power consumption, difficulty in starting for the first time, and corrosion.

However, in practical applications, the main key technical problems faced by forward osmosis and membrane distillation are: For forward osmosis, due to the dilution of the extraction agent in the process, the osmotic pressure is reduced, and the water flux is reduced, so a higher concentration cannot be achieved. The degree of concentration is generally 14%-15%. For membrane distillation, 90% of the energy consumption in the membrane distillation process comes from the heating of the raw material liquid, and there is a phase change on the interface on both sides of the membrane, which makes the heat loss higher, resulting in increased energy consumption

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