SU710965A1 - Method of processing spent regeneration solution of sodium cation exchange filter containing calcium sulfate - Google Patents

Description

one

The invention relates to a method for treating spent regeneration solutions of ion exchangers filters and can be used in water treatment for softening and decarbonizing water.

There is a known method of water softening, according to which the regeneration of Nd-cationite and C1-anionite filters is performed with a fresh solution of common salt, and the regeneration of Na-cationite filters with a regenerated solution of salt C1-anionite filter fl.

The disadvantage of this method is the presence of significant amounts of waste regenerative water treatment water, a relatively high consumption of salt for regeneration. In addition, the method is applicable only with increased salinity of the source water with a relatively small proportion of bicarbonate ions; in other cases, fresh sodium chloride solution is used to regenerate the Nc-carbonation and C1 anion-exchange filters.

The closest to the proposed method to the technical essence and the achieved result is the method of processing the spent regeneration solutions of NOI-cationite filters,

containing calcium sulphate, putt of crystallization of calcium sulphate on the seed.

However, the solutions obtained by a known method after treatment contain a significant amount of calcium, so using them to regenerate MSL-CH - onite filters cannot inevitably cause deposits of calcium sulfate and calcium carbonate in the loading layer of ion exchange filters.

The purpose of the invention is to provide the possibility of using purified solutions for the regeneration of Na-CE ion-exchange filters and to prevent the discharge of regeneration wastewater into water bodies.

The goal is to mix the “spent regeneration solution of the Nd-cationite filter after crystallization from it to the line with the spent regenerating solution of the C 1 -ionite filter with the succession by aerating the resulting mixture and treating it with a chemical reagent to a residual concentration of hardness salts 1-1 O mg-equant. Mixing of spent regenerative solutions of Nc -cate-6nite and C1 - aionite filters is carried out at 3-38 ° С. According to the proposed method, the repeated reuse of the spent salt solution j in the latter will result in the accumulation of β-sulfates, which must be precipitated by contact with a seed of gypsum from the used regeneration salt solution | 1 cationic filter in the form of Kalysh sulphate V Residual concentration of calcium sulphate (up to 80 mg-eq / l) corresponds to its limit of solubility. When mixing the spent regeneration solutions of the No-catconitic and C1 anionic filters, a salt solution is formed that contains Ca P1 ions. D. MattHCO3, C1, s, 0. Bicard &) calcium nat decomposes with the release of carbon dioxide: Ca (HCO) ,, .CaCOo, + CO + H, 0. When the temperature rises and the salt solution is aerated, the dissolved carbon dioxide is removed, which leads to an equilibrium shift to the right with decomposition of an additional amount of bicarbonates. ,,., - v2Ca (-.MgtOVO.-i-2Са with -V 2Н gO. If the salinity of the water being treated on Hcc – C6-ion-exchange filters, mainly due to ions NQ, Cot M, jVtCCh, wastewater treatment can be performed with applying relatively sky Larger amounts of lime are needed mainly for precipitation of magnesium from Mg (HCO3 |) 2 With a significant content of C1 ions in the source water, anions there are insufficient HCO in the effluent will not be enough to precipitate all hardness ions and in this case it is necessary to use soda: residual hardness and alkalinity of the working salt solution of 1-10 mg eq Soda can be replaced with sodium sulfate, which should be metered into the developed goli solution before the calcium sulfate crystallizes in the seed of the gypsum. Instead of lime and soda, caustic soda is also possible. In rare cases with an excess of HCO to 50d ions, calcium chloride with lime may be required. Increasing the concentration of the treated salt solution is carried out by adding table salt. Since the crystallization process of calcium sulfate is intensified with an increase in temperature, salt solution with a temperature not exceeding 4 ° C is used to regenerate the NOI-cation-exchange filter (the risk of gyration of the cation exchanger decreases). With the same purpose, the regeneration of the No-cation filter is carried out at a rate of 10 m / h with a salt solution with a concentration of sodium sulphate up to 1-3%. Thus, mutual purification of the spent regeneration solutions of the salt of the Na-cation-exchange and C-anion-ion filters is carried out, due to the ions of the NSO that are removed from the source water. PRI me R 1. MonS1-ion-exchange filters are supplied with water containing 7.3 mg eq / l, 2 mg-eq / l, HCO3 4.4 mg-eq / l,, 9 mg-eq / l, C1 0, 02 mg eq / l. The spent regeneration solution of the salt of the Nol-hathionite filter is contacted for 1 hour with the precipitate of calcium sulfate at 4O C. After settling, the spent regeneration solution of the salt of the N a-cation-exchange filter containing 70 meq / l of calcium sulfate is mixed with the spent regeneration salt solution C1-anion-exchange filter and aerate for 0.5 h at 4O C. With aeration, alkalinity decreases from 78 to 18 mg-eq / l and calcium hardness from 75 to 15 mg-eq / l (M 34) mg- eq / l Then, NaCC mg-eq / l and alkaline reagents (KS12.CO ,, 31 mg-eq / l and Ca (OH) 249 49 mg-eq / l) are metered. After settling, the clarified salt solution has the following characteristics: Mo | 8OO mEq / L, mEq / L, eg 850 mEq / L, and is used for post-regeneration No-cation-BibiX and CE-anion-ion-exchange filters. PRI mme R 2. Na-Cl ion exchanger filters supply water with the characteristics / specified in Example 1. The spent regeneration solution of the salt No of the cation filter is contacted in the process lO min. with salting kn, .c) at 8 ° C. After settling, the spent regeneration solution of the salt of the NO-cation-exchanger filter containing 60 mEq / l of calcium sulfate is mixed with the spent regeneration solution of the C1-anion exchanger filter and aerated for 1 O min. Alkalinity decreases from 78 to 5 mEq / L and calcium hardness from 75 to 2 mEq / L (Mg-34 MG-EKB / L). Then, dosing of NaSb (15O mEq / l) and alkaline reagents are performed. (31 mg-eq / l and C (OH) about 39 mg-eq / l). After settling, the clarified salt solution is cooled down and sent for regeneration of the Na-cation-exchange filter. To regenerate the C1-anion exchanger filter, a salt solution is used without cooling at 6 ° C. Thus, the proposed method prevents the discharge of regeneration wastewater from water treatment by treating and reusing spent regeneration salt solutions and reducing reagent costs of 30% by decreasing the NaCt solution Formula 1: Method for treating spent regenerative solutions of Na-cationite filters calcium sulfate, including the crystallization of calcium sulfate on gypsum seeds, characterized in that, in order to be able to use purified solutions for the regeneration of Na-C6 ion filters and preventing the discharge of regeneration wastewater into the reservoirs; after crystallization, the spent regeneration solution of the Ma-cation-ion filter is shifted with the spent regeneration solution of the C1-ashunite filter; 1 mg eq / l. 2, the method according to claim 1, wherein the mixing of the used regeneration solutions of the Na-cation-exchange and C 1 -anion-exchange filters is carried out at 30 ° -80 ° C. Sources of information taken into account in the examination 1.Lifshchits O.V. Handbook of water treatment boilers. Energy, M, 1976, p. 26-28, 70-80. 2. USSR author's certificate No. 482176, cl. In OlD 15 / O6 10/18/76 (prototype).

Claims (2)

Claim 1. The method of processing spent re- ' ^{, l} * generation solutions of Να-cation exchange resin 6 filters containing calcium sulfate, including crystallization of calcium sulfate on gypsum seeds, characterized in that, in order to enable the use of purified solutions for the regeneration of Na-C £ ionite filters and to prevent the discharge of regeneration wastewater into water bodies, the spent Na regeneration solution after crystallization -cationite filter is mixed with the spent regeneration solution of the C1-anionite filter, the resulting mixture is aerated and treated with a chemical reagent to a residual concentration walkie-talkies of salts of hardness 1-10 mg-equiv / l. 2, The method of π. 1, with the fact that the waste regeneration solutions of the α-cationite and C1 – anionite filters are mixed at 30–80 ° С.