SU1452797A1 - Method of treating water - Google Patents

Abstract

The invention relates to a technique for the treatment of water by the ion-exchange method and can be used in water-supply systems. The purpose of the invention is to increase the degree of water purification, reduce the amount of mineralized effluent, simplify and reduce the cost of the method. The method involves treating water in the clarifier with lime solution, subsequent H-cationization and regeneration of the cation exchanger with a solution of sulfuric acid, and before regeneration, a solution or suspension of the calcined carbonate precipitate of the clarifier is passed through the H-cation filter. The resulting solution is used to process the source water in the clarifier, and the H-filter regeneration is carried out in a closed loop until the acid is completely used. The solution or suspension of the calcined carbonate precipitate is passed through an H-cation resin filter until the complete removal of magnesium ions. It is advisable to pass the solution or suspension of the calcined carbonate sediment through a part of the layer of depleted cation exchanger in the Mg, Na form in the scheme of chemical desalting. 2 hp f-ly. h s cl

Description

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The invention relates to a technique for processing a node and can be used in the power engineering, chemical, electronic, and petroleum refining industries with water treatment facilities.

The aim of the invention is to increase the degree of water purification, reduce the amount of mineralized effluent, simplify and reduce the cost of the process.

The method involves treating water in a clarifier, H-cationizing water, regenerating the H-cation exchanger, while passing through the H-cationic filter, before regenerating, passes a solution or suspension of the calcined carbonate sediment of the clarifier, and the resulting solution is used to treat the source water in the clarifier, and regeneration H-filters are led in a closed loop until the acid is completely used.

The solution or suspension of the calcined carbonate precipitate is passed through the H cation-exchange filter until almost complete displacement of Mg.

In the chemical desalting scheme, a solution or suspension of the calcined carbonate precipitate is passed through a portion of the depleted cationite layer in the Mg, Na form.

Passing a solution or suspension of calcined carbanate sediment through an H-cation filter before regeneration allows you to simultaneously increase the degree of water purification in the clarifier for calcium, and on the H-cation filter for sodium to ensure best-quality regeneration of the H-filter with 100% use acid. An increase in the degree of purification of water in calcium is associated with the supply to the clarifier of a mixture of alkaline compounds of Mg and Na, obtained as a result of passing a solution or suspension of calcined carbonate sediment through the exhausted H-cation filament. The Na ions retained during the H-cationization return to the clarifier in the composition of alkaline compounds of magnesium and sodium and in a certain mixture with Ca hydroxide to contribute to a deeper calcium deposition than in the known method. At the same time, the anionic composition of water in the clarifier is not impaired,

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The total salinity of the treated water does not increase.

In contrast to the known method, the anionic component of the solution supplied to the clarifier is reactive and is maximally realized in the process: e sedimentation. At the same time, the lime consumption introduced into the clarifier is significantly lower than by a known method. In the known method, the liming is carried out in the hydrate mode, and the dose of lime exceeds the required one by the amount of magnesium returned to the clarifier. In the proposed method, the lime consumption is lower than that required for hydrate precipitation. The resulting precipitate has a more uniform carbonate composition, which, after calcination and dissolution, is used to dehydrate the N-cation exchanger. The described cyclic process causes the reagent-free softening of water by Ca in the clarifier, the effectiveness of which exceeds the reagent softening of water by commercial reagents - Ca (OH) and. So, the residual calcium hardness of the treated water in the proposed method is 0.28-0.3 mg-eq / l versus 0.6 mg-eq / l in the known method. This is achieved by co-treating the raw water with a mixture of calcined carbonate sediment and alkaline compounds of hydroxides of Ca, Mg, Na, obtained by passing a solution or suspension of calcined carbonate sediment through an H-cation filter. The content of Na in the clarified water is also lower; 1.4 mg eq / l versus 3.66 mg eq / l as known by eliminating the consumption of soda for precipitation.

The degree of water purification achieved in the proposed method allows it to be used directly after the clarifier without additional drainage to feed heating systems, circulating cooling systems and other systems that use softened water, which significantly expands the technological capabilities of the method, as it allows a chemical desalting scheme for softened water without additional reagent costs, while maintaining the best-available technology.

The proposed method provides a simplified and cheaper process for

by eliminating the consumption of soda and reducing the consumption of lime for treating water in the clarifier, as well as by implementing the H-cationization stage in one step with deep removal of both hardness and sodium cations at the same time. In a known method, an H-filter loaded with KB-4 provides deep removal of stiffness, and additional H-cationation on the filter loaded with KU-2 is changed to remove sodium. Fragile-free regeneration of the H-filter with full utilization of the acid solution is also achieved by passing a solution or suspension of calcined carbonate sludge through a depleted H-cation exchanger (in mixed Ca, Mg, Na-form), resulting in almost complete cation exchanger before regeneration with acid. homogeneous calcium form. It is washed with a part of the wash water of the H-filter and passed upwards. When it is regenerated by a solution of sulfuric acid in a closed circuit: H-filter - settling tank (reactor), calcium sulfate is precipitated. The recovered solution is supplemented with H, 504 and repeatedly used. it is consumed, at this expense, for the addition of stoichiometric calcium displaced from the load. According to a known method, repeated reuse of the acid in a closed loop would be impossible, since it would lead to the accumulation of Mg2 in solution and would worsen the degree of regeneration of the cation exchanger.

Since an excess of acid is not removed from the cycle, but is fully realized in the process of multiple circulation through a cation filter, the proposed method achieves the maximum possible degree of regeneration of the cation resin with the reconstituted solution. The reinforcement of the recovered solution, fresh, taken in an amount stoichiometrically pressed into the Ca2 H filter, is not performed by direct dosing, but by additional passage through the already regenerated cation exchanger. This makes it possible to almost completely displace residual calcium from the lower layers of the cation exchanger due to the use of fresh concentrated regenerant at the final stage.

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(MO-20%), not containing Ca ions. With such a regeneration of cation exchanger KU-2 with stoichiometric consumption, the residual rigidity of the filtrate is 1 µg-eq / l, i.e. 5 times lower than in the known method (5 µg-sqv / l), and the sodium content is less than 0.1 mg-eq / l, i.e. 26.6 times lower than in the known method. Thus, in the proposed method, a higher degree of water purification is achieved, both after the clarifier and after the H-cation filter in 5 chemical desalting scheme. ;

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Passing a solution or suspension of calcined carbonate sediment through an H-cation filter to almost completely displace Mg, and therefore single-charged Na ions, maximally increases the efficiency of using calcined carbonate sediment in the clarifier, and also provides the possibility of repeated repeated use of stoichiometric acid, so how solid waste is removed from the cycle in the form of SAZod.

According to a known method, the extrusion of magnesium and sodium from the cation exchanger and their supply to the clarifier in the form of magnesium and sodium sulfate lead to the contamination of water with sulfates and the need to increase the consumption of lime for the precipitation of Mg.

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In the chemical desalting scheme, a solution or suspension of the calcined carbonate precipitate is passed through a portion of the layer depleted of the cation exchanger in the Mg, Na form. This allows you to save all the reactive H ions remaining in the bottom of the load when the H-filter is cut off by the flow rate of Na in the chemical desalting scheme and to avoid partial neutralization of the passed-through solution. The solution or suspension of the calcined carbonate precipitate is introduced into the filter through an intermediate drainage system located above the zone of the remaining H-ions, and the output of the cationized solution is produced through the upper distributor.

An example. The H-filter with an intermediate drainage system is loaded with 200 ml cation exchanger KU-2. The source water is processed to the following "composition,

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mg-eq / l: .Z; Mg 2.0; Na 0,

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1.5; Cl- 1.1; HCO 3.9.

The content of components in the initial water, filtrate, solution of calcined carbonate sediment and regeneration iJacTBOpe acid is determined by the following methods:

Na - by flame photometry;

I Ca, Mg2 - by the titrimetric method with the use of trylon B;

H - by the method of titration using dosage of 0.01 n. and 0.1 and solutions of caustic soda;

C1 - mercumetric method using the definilicarbosone; I 50 - by the bulk chromatic method I OH, HCOj - by the titrimetric method I by the method of dosing 0.01 n. and 0.1N, HC1 and the use of phenolphthalene and methyl orange.

Preliminary experiments for this composition of water determine the height of the lower layer of the cation exchanger, which contains reactive H ions at the time of sodium leakage. At this height, an intermediate drainage system is established. The H-cation filter is disconnected along the passage of Na - 0.1 - 0.15 mEq / l.

After the H-filter is depleted, a solution of calcined carbonate sediment (Ca concentration - 40 mg eq / l) is fed to the intermediate drainage system until Mg is completely displaced, and the cationized solution of the cherns filter is removed from the upper filter distribution unit. The composition of the obtained jpacTBopa, mEq / l: Ca 27.7; Mgj8.48; Na 3.82.

The resulting solution, together with the calcined carbonate precipitate, is treated with the source water in the clarifier. The residual calcium hardness of the treated water after the clarifier is 0.28 mEq / L, and the residual sodium content is 1.4 mg eq / L. 50% gchennoy's mind the water clarifier water is used to feed the cooling system and ipOTHoro cooling and 50% to the H- | filter of the chemical desalting unit. A 2% solution of sulfuric acid is passed through the H-filter from bottom to top along a closed circuit. The H-filter is a settling tank (reactor) until equilibrium of the cation exchanger with the solution is reached. In the sump (reactor) there is a precipitation of the solid phase SABOTS.

the exact concentration of Ca in the acid solution is 30 mEq / L. Then through the H-filter, an additional 10% solution of sulfuric acid is passed in an amount equal to the previously displaced calcium, followed by feeding a strong solution after the filter to the sump (reactor). As a result, the regeneration solution is strengthened, which is used in the next regeneration cycle. The residual stiffness of the filtrate obtained is less than 1 µg-eq / L, and

residual sodium; 60-100 μg-eq / l. In contrast to the known in the proposed method, a higher quality of water after the clarifier and H-filter was obtained, the costs of scarce soda for the treatment of the source water in the clarifier were eliminated and the NaOH expenses for the regeneration of anion-exchange filters were reduced, the softened water was additionally obtained, the salt content was reduced.

clarified water.

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Claims (3)

1. A method of treating water, which includes water clarification with a lime solution, subsequent H-cationization and regeneration of the cation exchanger with a solution of sulfuric acid, so that, in order to increase the degree of water purification, reduce the amount of mineralized draining, simplifying and reducing the cost of the process, before regeneration, a solution or suspension of the calcined carbonate sediment of the clarifier is passed through the regeneration, the resulting solution is used to treat the source water in the clarifier, and the regeneration of H-fIlt and are in a closed circuit to fully utilize the acid. 2. A method according to claim 1, characterized in that the solution or suspension of the calcined carbonate precipitate is passed through an H-cation resin filter until almost complete displacement of Mg. 3. The method according to claim 1, characterized in that in the chemical desalting scheme, the solution or suspension of the calcined carbonate precipitate is passed through a portion of the depleted cationite layer in the Mg, Ka-form.