Method and system for recycling regenerated waste liquid of sodium bed

Abstract

The invention relates to a method and a system for recycling the regenerated waste liquid of a sodium bed. The method comprises the following steps: adding polymerization ferric chloride or polymeric ferric sulfate or a polymeric aluminum solution into waste liquid by virtue of waste liquid detection according to needed addition amount, then sequentially adding NaOH or lime, and then adding Na2CO3, so that divalent ions Ca<2+> and Mg<2+> in the waste liquid form an aggregate, and the aggregate is subjected to pressure filtration by virtue of a pressure filter and then is subjected to solid-liquid separation; and regulating the pH value of a separated pressure filter clear liquid, supplementing NaCl for the pressure filter clear liquid, and sequentially performing fine filtration by virtue of an immersion type ultra-filter to obtain the recyclable regenerated waste liquid of the sodium bed, wherein the total calcium-magnesium amount is smaller than 40mg / L, the SS is smaller than or equal to 0.1mg / L, and the turbidity is smaller than or equal to 0.1NTU. According to the method and the system, the divalent ions in the regenerated waste liquid of the sodium bed can be effectively removed, the continuity of the treatment process of waste salt water is realized, each treatment period is about 8 hours, the zero-emission and the continuous regeneration of the regenerated waste liquid of the sodium bed are realized, and the system is simple in structure, stable to operate and suitable for industrial application.

Description

technical field [0001] The invention belongs to the technical field of waste water treatment research, in particular to a method and system for recycling sodium bed regeneration waste liquid capable of removing calcium and magnesium ions in sodium bed regeneration waste liquid and realizing zero discharge and continuous regeneration of sodium bed regeneration waste liquid . Background technique [0002] General industrial water supply and wastewater reuse are softened by sodium ion exchangers. After a period of use, the exchange capacity of sodium ion exchange resins decreases. Sodium chloride needs to be used to regenerate the sodium ion exchange resins to restore their exchange capacity. . [0003] At present, resin regeneration is mostly soaked in brine (4-6% NaCl solution) to make the resin layer take effect again, and the dosage is about 1.5 times of theoretical calculation. The main mechanism is that the calcium (Ca 2+ ), magnesium (Mg 2+ ) ions are replaced to gen...

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Problems solved by technology

The technology CO 2 The gas supply device is more complicated, and the CO 2 The reactivity of the Mg(OH) 2 The sedimentation speed of the formed flocs is slow, and there are deficiencies such as incomplete solid-liquid separation.

[0007] The above methods are affected by two factors: incomplete removal of high brine hardness or incomplete solid-liquid separation. If it is used to regenerate the sodium bed, it is easy to cause incomplete regeneration or fouling of the resin layer, resulting in a decrease in resin exchange capacity and an increase in annual loss rate; On the other hand, the density of waste brine is generally about 1.33g / mL, while the particle size of magnesium hydroxide produced by the softening reaction is only a few to tens of microns, and it is flocculent, difficult to settle by gravity, and solid-liquid separation is difficult. Generally, the product water is treated and the turbidity is greater than 40NTU, and the filtration equipment (such as centrifuge, vacuum filtration equipment, etc.) used in the existing system is easily destroyed by Mg(OH) 2 Blockage, short replacement cycle, affecting the efficiency of the sodium bed and the continuity of the treatment process

[0008] In summary, the current sodium bed regeneration waste brine has the characteristics of difficult solid-liquid separation, long regeneration cycle and poor continuity to varying degrees when it is recycled.

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