DD262595A5 - METHOD FOR THE REGENERATION OF ION EXCHANGERS AND THE LAND USE OF THE REGENERATES - Google Patents

Abstract

The invention relates to an environmentally friendly process for the regeneration of ion exchangers and the agricultural use of the regenerate. According to the invention, aqueous solutions of salts containing vegetable main nutrient elements, preferably commercial art formers, and / or acids and / or alkalis likewise containing vegetable nutrient elements are used as regeneration liquid. The resulting regenerated material is neutralized if necessary and either applied directly as a liquid Kunstduenger or used as an additive to Duengerkompositionen. In this way, an economically important product like Kunstduenger is used twice in a row without any special precautions being taken. The main advantage is that there are no solutions with a high content of NaCl, whose destruction, processing or final storage causes difficulties.

Description

Field of application of the invention

The invention relates to a process for the regeneration of ion exchange resins and agricultural use of the regenerate. The process can be used to regenerate both cation and anion exchange resins

 The main field of application of the invention is the preparation of boiler feed water and make-up water for heating plants, cogeneration plants, thermal power plants and district heating systems and the energy-producing industry, but it can be applied everywhere where there is a need to completely or partially free water by ion exchangers from the ions contained in it.

Characteristic of the known state of the art

The ion exchangers used for partial or complete water softening must, when completely mixed with ions

loaded, i. are exhausted, regenerated. Not so long ago, the most important criterion when selecting regenerants was the price. Therefore, sodium chloride, sodium hydroxide, sodium carbonate, hydrochloric acid, sulfuric acid or mixtures of the listed substances have generally been used. The resulting regenerates were at most

neutralized and then discharged into the sewers or the open waters. The water purification plants of 15-20 year old power plants and heating plants are for the most part still dimensioned and built for this technology. The 5-10%

Sodium chloride and sodium sulfate solutions were then treated with other wastewater (for example, cooling water, bath water).

further diluted.

However, with the ever-increasing development of environmental protection, strict regulations have also been issued to protect water quality. Saline industrial wastewater discharged into sewers shall not contain more than 0,15% salt and must be approximately neutral.

Already in medium-sized remote heating plants, thousands of cubic meters of approximately 10% saline solution are produced annually

Disposal difficulties.

Theoretically, there is the possibility of the regeneration solution, possibly after an intermediate storage, with wastewater and

Dilute tap water (drinking water) until the prescribed concentration limit is reached. This can not be done for reasons of water saving. As calculations show, this would be about 77-97% of the

Refill water of the entire primary transmission network required, i. the water consumption of the heating plant would almost double.

Methods are also known for purifying the chemicals used and their reuse. According to the

Hungarian patent no. 177 506, precipitated calcium and magnesium with sodium carbonate in the form of CaCCb or _MgCO3. The soda excess is then neutralized with hydrochloric acid. As in the laboratory conducted model experiments, is the

Chemicals require the process high, the required filter, storage and CC ^ -absaugvorrichtungen are expensive, and the final storage of the resulting carbonate precipitate is difficult.

The treatment with filter membranes is not suitable for the purposes of energy and district heating plants for cost reasons.

In addition, the resulting concentrate must then also be disposed of.

Finally, it is still possible to use the salt solutions for de-icing the roads in winter. Because of the seasonal nature of this use, the attempt has not been made seriously, because the amounts accumulating in the summer would then have to be stored temporarily. It is not possible to dump the solutions in agricultural areas; Dumping on sandy and pebbly soils would increase the salinity of the groundwater.

Explanation of the essence of the invention

Object of the invention was to find regenerants for regenerating ion exchangers, which give an environmentally friendly, recyclable reclaimed and besides cheap and easily accessible.

The invention is based on the finding that salts containing main vegetable nutrient salts, preferably commercial artificial fertilizers, as well as main vegetable nutrient-containing acids and bases in the form of aqueous solutions for the regeneration of ion exchangers are excellently suitable because they give a regenerate which can be used agriculturally.

The invention accordingly provides a process for the regeneration of ion exchangers and the agricultural use of the regenerate. It is characteristic of the process according to the invention that the aqueous solution of salts containing plant main nutrients, preferably artificial fertilizers, and / or acids and / or alkalis also containing vegetable nutrients are used for regeneration and the resulting regenerate is applied either directly as liquid fertilizer after neutralization if necessary or used as an additive to fertilizer compositions.

Potassium fertilizers which are used as main vegetable nutrient elements are, in particular, suitable as a solution having a 5-15% KCl content on the exhausted ion exchanger filling after it has been slightly loosened up by countercurrently passed water. It is convenient to prepare the KCl solution with heating because, on the one hand, the negative heat of solution of KCl is considerable and, on the other hand, its solubility increases exponentially with increasing temperature.

As additional salts potassium nitrate and sodium nitrate fertilizers can be cited.

As plant nutrients containing acids and alkalis are, for example, nitric acid, phosphoric acid or potassium hydroxide and ammonium hydroxide in question.

Ion exchangers in neutral form (Na ⁺ form or after the regeneration according to the invention in K ⁺ form), when exhausted, are regenerated with aqueous solutions of fertilizer salts. The regenerate contains firstly the excess of the fertilizer salt used, secondly the calcium and magnesium content of the previously purified on the ion exchanger water and thirdly trace elements, the micronutrients and trace elements such as iron, manganese, copper, zinc, cobalt, molybdenum in prepurified river water, groundwater always available; During the softening of the water, they accumulate in the ion exchanger and reach regeneration during regeneration. Regenerate is therefore more valuable than normal fertilizer solutions that do not contain these elements.

Depending on the composition of the raw water and the target to be achieved (partial desalination, demineralization, absence of carbonate, carbonate reduction), it may also be necessary to use ion exchangers in the H ⁺ form or the OH ~ form. The former are regenerated with one of the acids mentioned, the latter with one of the said alkalis. It is clear that the resulting regenerates must be neutralized before they are used in agriculture. If one uses to neutralize also main vegetable nutrient-containing chemicals used (ie, for example, a nitric acid regenerate neutralized with ammonia, or an ammoniacal with phosphoric acid), we obtain a valuable all-fertilizer solution.

The use of optionally neutralized regenerates in agriculture can be done by direct application as a liquid fertilizer. However, the regenerates may also be used in fertilizer compositions such as fortified peat, fecal or animal manure, clay mineral based fertilizers and soil improvers. This use in compositions is important because the regenerates occur all year round, but the liquid fertilization is seasonal. The enriched with the solution peat compositions are particularly popular in the hobby gardening.

The invention has the following main advantages.

An economically important product such as artificial fertilizer is used twice in a row without the need for special precautions. The artificial fertilizer is dissolved, used to regenerate exhausted ion exchangers and then fed to its proper destination. As a result, the chemical consumption of the regeneration is zero. It should be emphasized that with the method according to the invention the formation of the strongly NaCl-containing regenerates is avoided, that is, the method is environmentally friendly. Finally, it should be emphasized that all these benefits cost practically nothing, since all the technology of water treatment remains the same. Only a small storage capacity is to be expanded, and for the removal of the solutions to the place of use (for example, a large nursery) must be taken care of.

embodiments

The invention will be explained in more detail with reference to the following examples.

example 1 Water softening by cation exchange

In a cylindrical, 2000 mm high ion exchange device of 625 mm diameter 0.46m ^{3 of} the beaded cation exchanger VARION KS (matrix: PolyiStyrol / divinylbenzene), active group: -SO3H ⁺ ) filled. The water softening takes place at a temperature of 18 ° C and a flow rate of 45 m / h and a throughput

the softening 0.46 0.47 4.41 0.09 0,008 1.44 0,002 0.72 <0.3 <0.3 3.70 3.70 0.54 0.54 0.32 0.32 0.01 0.01

of 13,8m ³ / h. The ion content of the water before and after softening is as follows:

lon before after

Sodium (mol / m ³ ) potassium (mol / m ³ ) calcium (mol / m ³ ) magnesium (mol / m ³ ) iron + manganese (g / m ³ ) bicarbonate (mol / m ³ ) chloride (mol / m ³ ) Sulfate (mol / m ³ ) nitrate (mol / m ³ )

As you can see, the Ca ⁺⁺ and Mg ⁺⁺ ions are exchanged for K ⁺ ions (if you were to regenerate in the usual way with NaCl, then Na ⁺ ions would be in the water instead).

After producing 159.7 m ^{3 of} softened water, the charge of the ion exchanger is regenerated in the same flow direction. For this purpose, from 180 kg of potassium chloride artificial fertilizer (AK ₁ according to the Hungarian standard no. MSZ6275) with 1.8m ^{3 of} water at 30 ⁰ C prepared a 10% solution whose density is 1.0598. This solution flows through the ion exchanger at a rate of 2.5 m / h. The amount corresponds to a chemical excess of 250% (own experiments showed that the practical useful capacity of the resin VARION KS is 0.75 mol / l.)

The collected separately from the loosening and washing water regenerate has the following composition: potassium chloride 7.16%

Calcium chloride 1.41%

Magnesium chloride 0.61%

Sodium chloride 0.10%.

Potassium is a major vegetable nutrient, and calcium and magnesium are plant nutrients. The sodium content is insignificant.

With the Regenerat peat (locality: Nädasladäny, Hungary) is soaked. In each case one uses so much regenerate that the peat at 50% water content contains 2% by weight of artificial fertilizer (Hungarian standard MSZ 08 0015-78). The peat is excellent for horticultural purposes, for fertilizing ornamental plants, repotting of flowers.

Example 2 Water softening of cation exchangers to reduce the carbonate content (partial flow process)

Raw water containing 3.70 mol / m ^{3 of} bicarbonate is to be softened to a bicarbonate content of 0.2 mol / m ³ (exact composition see below). For this purpose, two ion exchange devices (2000 mm high, 0 625 mm) are filled with 0.46 m ³ each of VARION KS. Between both, an air blowing device is attached to remove the CO ₂ . One exchanger is filled with resin in H ⁺ form, the other with resin in K ⁺ form. It depends on the composition of the raw water and the desired freedom from carbonate to achieve the ratio in which the two exchangers must pass through each other. The ratio is calculated as follows:

H ⁺ partial flow mi - m ₂

K ⁺ partial current (-m) + m ₂

T ₁ is the m-basicity of the raw water, m ₂ the desired m-basicity to be achieved and (-m) the free acid content after passing through the H ⁺ resin. (The m-basicity (HCOJ and COJ ") is titrated against methylorganes, hence m-basicity The free acid content (-m) is the sum of CP, SOJ" and MO3 expressed in milliequivalents below quality results

m, m ₂ 3.70-0.20

  = 2.52.

(-m) + m ₂ 1.19 + 0.20

H ⁺ partial flow and K ⁺ partial flow behave accordingly as 2.52: 1, ie 71.6% of the water must pass through the H ⁺ exchanger.

The device with the H ⁺ resin must therefore be regenerated 2.52 times as often as the device with the K ⁺ resin.

However, if the composition of the raw water is constant, it is better to use a 2000 mm diameter device of 1000 mm diameter and fill it with 1.16 m ³ resin in the H ⁺ cycle.

Ion before

Sodium (mol / m ³ ) potassium (mol / m ³ ) calcium (mol / m ³ , magnesium (mol / m ³ ) Fe + Mn (g / m ³ ) hydrogencarbonate (mol / m ³ )

the softening 0.13 0.46 1.25 0.09 0.01 1.44 0,004 0.72 0.3 0.3 0.20 3.70

lon before after

the softening

Chloride (mol / m ³ ) 0.54 0.56

Sulfate (mol / m ³ ) 0.32 0.32

Nitrate (mol / m ³ ) 0.01 0.01

Both cation exchangers are regenerated with a chemical excess of 250%, namely the resin in K ⁺ form with the solution of 180 kg of potash fertilizer (AK ₁ of quality according to Hungarian standard MSZ 6275) in 1.8 m ^{3 of} water, and the column in H ⁺ Form with 6% nitric acid (prepared from 234.1 kg of 65% nitric acid by dilution with 2.3 m ^{3 of} water). The two regenerates are combined. The strongly acidic liquid is neutralized with 25% aqueous ammonia. This results in an additional content of ammonium nitrate, and the solution is suitable as a liquid fertilizer for agriculture.

Composition after neutralization (% dry substance)

Ammonium nitrate 53.54% CaCl ₂ 3.90%

Potassium nitrate 0% KCI 19.78%

Calcium nitrate 14.35% MgCl ₂ 1.67%

Magnesium nitrate 6.58%

Example 3 Water softening by cation and anion exchange

The water softening is carried out in three cylindrical ion exchangers of the dimensions given in Example 1. In one of the ion exchangers 0.46 m ³ KS cation VARION be filled in the other two per 0.46 m ³ anion exchange resin VARION AD (Matrix: poly (styrene / divinylbenzene), active group: alkanol N ^+). The two anion exchangers are connected in parallel, the cation exchanger in series with them. The water to be softened first flows through the cation exchanger at a rate of 45 m / h, then the two anion exchangers at a rate of 22.5 m / h. The power is 13,8m ³ / h, the water temperature 18 ° C.

Ion before

Sodium (mol / m ³ ) potassium (mol / m ³ ) calcium (mol / m ³ ) magnesium (mol / m ³ ) iron + manganese (g / m ³ ) bicarbonate chloride (mol / m ³ ) sulfate (mol / m ³ ) nitrate (mol / m ³ )

After 159.7 m ^{3 of} water have been softened, the system is regenerated. To regenerate the cation exchangers, a solution is prepared from 180 kg of potassium chloride artificial fertilizer (quality according to Hungarian standard MSZ 6275, ie high KCl content, small particle size) with 1.8 m ^{3 of} water while heating to 30 ^° C. All three ion exchangers are regenerated with this solution, the flow rate being 2.5 m / h and the flow direction being the same as when loading.

The regeneration is carried out in both cases with a chemical excess of 250%. (Our own investigations showed that VARION KS has a useful capacity of 0.75 mol / l and VARION AD has a useful capacity of 0.37 mol / l.)

The regenerated water collected separately from the loosening and washing water has the following composition: potassium chloride 7.10%

Calcium hydrogen carbonate 1.60%

Magnesium hydrogen carbonate 0.93%

Calcium sulphate 0.37%.

The potassium is a main vegetable nutrient, also calcium and magnesium salts are absorbed by the plants. The regenerate is particularly suitable for fertilizing acidic soils. However, it can also be used in the manner described in Example 1 for soaking peat.

Example 4 Complete desalting

Three lonenaustauschervorrichtungen (height 2000 mm, diameter 625 mm), each with two 0,46m ³ anion exchange resin VARION AD and the third with 0,46m ³ cation VARION KS be filled. The anion exchangers are connected in parallel, the cation exchanger is connected upstream in series. The cation exchangers are operated in the H ⁺ cycle, the anion exchangers in the OH ~ cycle. Between anion and cation exchanger is a Luftblasanlage for removing the resulting in the acidic medium from the bicarbonate

the softening 0.46 0.46 4.41 0.09 0,006 1.44 0,002 0.72 0.3 0.3 0.01 3.70 4.85 0.54 0.01 0.32 0,003 0.01

Provided carbon dioxide. The water to be softened passes through the cation exchanger at a rate of 45 m / h, the anion exchanger at a rate of 22.5 m / h. At a throughput of 13.8 m ³ / h, 159.7 m ^{3 of} water are desalted.

ion in front complete desalination to Sodium (mol / m ³ ) 0.48 0.00 Potassium (mol / m ³ ) 0.08 0.00 Calcium (mol / m ³ ) 1.44 0.00 Magnesium (mol / m ³ ) 0.72 0.00 Fe + Mn (g / m ³ ) <0.3 0.00 Bicarbonate (mol / m ³ ) 3.70 0.00 Chloride (mol / m ³ ) 0.54 0.00 Sulfate (mol / m ³ ) 0.32 0.00 Nitrate (mol / m ³ ) 0.01 0.00 specific electrical Conductivity pS / cm <1

The cation exchanger is regenerated with 8% nitric acid, the anion exchanger with 4.45% ammonia, the flow rate is 3 m / h and a 250% excess of chemicals is used.

The regenerate has the following composition (% solids content):

Ammonium nitrate 57,76%

Calcium nitrate 23.50%

Magnesium nitrate 10.62%

Ammonium sulfate 4.21%

Sodium nitrate 2.03%

Ammonium chloride 1.44%

Potassium nitrate 0.45%

Each component is nitrogenous; The ammonium nitrogen has a lasting effect, the nitrate nitrogen acts immediately. At this point it should be noted that the regeneration of the cation exchanger in H ⁺ form is made appropriately depending on the season. In autumn, potash and phosphorus fertilization is common, so phosphoric acid should be regenerated in autumn, while nitric acid is preferable in spring (potash nitrogen fertilization).

Example 5 Drinking water preparation

The quality of the drinking water is prescribed in standards. The requirements for total hardness and total salt content can be met by the technologies described in the previous examples. The Hungarian drinking water standard (MSZ 450/1) stipulates that the total hardness should be between 1.786 and 12.5 mol / m ³ . Assuming a water of total hardness 25.0 mol / m ³ with the aim of making it pleasant drinking water (5 mol / m ³ total hardness), it is sufficient to soften 80% of this water.

Claims (6)

1. Environmentally friendly process for the regeneration of ion exchangers and the
agricultural use of the regenerated, characterized in that as
regenerating liquid, the aqueous solution of plant main nutrient-containing salts, preferably commercially available fertilizers, and / or also herbal
Nutrient elements containing acids and / or alkalis used, the resulting regenerate
neutralized if necessary and either directly as a liquid fertilizer, or as
Addition to fertilizer compositions used. 2. The method according to claim 1, characterized in that one cation exchanger,
optionally together with anion exchangers, regenerated with the solution of potassium chloride fertilizer. 3. The method according to claim 2, characterized in that the regeneration solution is prepared with warm water and a concentration of about 5-15Ma .-% sets. 4. The method according to claim 1, characterized in that in the partial
Carbonate elimination exhausted cation exchangers in K ⁺ and H ⁺ form simultaneously regenerated, namely the H ⁺ form with aqueous nitric acid or phosphoric acid and the K ⁺ form with the
aqueous solution of a potassium-containing fertilizer salt, which combines regenerates, with ammonia
or potassium hydroxide neutralized and the obtained, rich in plant nutrients solution in the
Uses agriculture as artificial fertilizer. 5. The method according to claim 1, characterized in that in the process of complete desalination exhausted ion exchangers in H ⁺ - and ΟΙ-Γ-form regenerated simultaneously, namely the
Anionenaustauscher with ammonia or potassium hydroxide, the cation exchanger with nitric or phosphoric acid, and the resulting complex fertilizer solution in agriculture as
uses liquid artificial fertilizer. 6. The method according to claim 4 or 5, characterized in that regenerating the cation exchanger in H ⁺ form in the spring with nitric acid, in the autumn with phosphoric acid.