SU1189810A1 - Method of softening water - Google Patents

Abstract

A WATER TREATMENT METHOD, including passing it through a cation filter, regenerating the latter with metal chloride solution and processing the spent regeneration solution with a chemical reagent for precipitating hardness ions, characterized in that in order to create an effluent-free technology by enabling the resulting effluent to be used as mineral fertilizers , regeneration is carried out with a solution of potassium chloride, and alkaline potassium is used as a chemical reagent for precipitating ions — hardness. effluent purging steam boilers fed K-cationized water, pre-saturated with carbon dioxide. 00 from 00

Description

1 The invention relates to a method of water softening and can be used in water treatment for powering energy and other plants having ion exchange filters for water cationization. There is a known method of water softening by hydrogen-cationation, based on the substitution of Ca hardness cations and an equivalent amount of H cations. The reduction of the isotat cation exchanger is made by a working regeneration solution of sulfuric acid Cl. The disadvantage of this method is the presence in the wastewater of regeneration of excess sulfuric acid and gypsum, which requires high costs for cleaning them, in order to protect the environment and protect water treatment equipment from corrosion of sulfuric acid. The closest to the proposed technical essence and the achieved result is a method of water softening, including passing the water through a cation filter, regenerating the latter with sodium chloride solutions and treating the spent regeneration solution with lime to precipitate hardness ions in the form of CaCO ,, MgCOj and MgCOH) 2 A disadvantage of the known method is the formation of wastewater containing an excess of NaCi, salinizing the soil and water bodies, which adversely affects the environment. In view of the good solubility of compounds on ri in water, the latter are difficult to remove components, which requires evaporation of saline effluent followed by their disposal. The purpose of the invention is to create a drainless technology by providing the possibility of using the resulting effluent as a mineral fertilizer. The goal is achieved by the fact that according to the water abatement method, it is passed through a cationic filter, the latter is regenerated with a solution of potassium chloride and the recycled regeneration solution is treated with a chemical reagent, which uses alkaline potassium wastewater; boilers fed with K-cationized water, preliminarily fixed with carbon dioxide. 02 The drawing shows the scheme of the method. The scheme contains a cation-exchange filter 1, supply water supply line 2 or regeneration solution, averaging tank 3 for drainage, mixer-settling tank 4, carbonizer 5, potassium alkaline potassium discharge line 6, steam boilers 7, carbon dioxide supply line 7 and line 9 removal of potassium chloride solution. Example. Through the cation filter 1, the source hard water is passed from top to bottom. The process of cleansing water proceeds according to the formula 2R - K + Ca (HCOj) Ca. + 2KNSO. . After saturation of the cation exchanger with hardness ions, a solution of potassium chloride is fed through line 2 at 20–30 s and pressure of 3–3.5 kgf / cm for 20–40 min. For regeneration of the standard production filter - 1500 mm, 230-250 kg of technical KCI is needed in the form of a 6-10% solution. The regeneration process proceeds according to the formula Ca-n 2KC1-2R - K + CACT 2. Regeneration drains containing CaCI, MgCbj. and an excess of KC1, is sent to an averaging tank 3 and then to a mixer-settler 4, to which purge water saturated with carbon dioxide is supplied. from carbonation tank 5. Pre-purge water of steam boilers fed with water after potassium cationization, containing KOH in the amount of 3-5 g / l, through line 6 enters carbonizer 5, where carbon dioxide is injected through line 7. The source of carbon dioxide is the exhaust flue gases of industrial processes. The interaction of the blowdown effluent and carbon dioxide occurs according to the formula 2KOH + C02 - KjCO +. The reaction takes place at 80-100 ° C, generated by the heat of the purging effluents and flue gases, while the excess heat is removed through the heat exchanger. The interaction of the purge waters filled with carbon dioxide and the effluent of the regeneration of K-cation-exchange filters takes place according to the formula

СаСБ2 + KjCO, CaCOg + 2KCl;

MgCtj + 2KOH Mg (OH) j + KCf. With a different composition of the source water, the optimal controlled carbonization process and the interaction of the wastewater reagents to ensure maximum depth of purification and conversion to

4-t

, - precipitation of compounds Ca - and Mg is possible at a ratio in mixed effluents

  but

-

20H

As a result of the above t5 reaction in the mixing chamber, carbonate of CaCO and magnesium hydroxide Mg (QH) 2 precipitate out in the form of sludge removed via sludge line 8 for mechanical cleaning. A recovered solution of potassium chloride is removed from the upper 20 zone of the mixing chamber through line 9 for mechanical purification and further use as a mineral bath 25 or a recycling reagent during regeneration. Excess carbon dioxide is vented to the chimney.

Comparative data on the effectiveness of the proposed and known methods are presented in the table.

Thus, the proposed method, compared with the known ones, allows the use of treated effluents as mineral fertilizers and, thus, 100% exclude contamination of the environment with the drainage of ion-exchange filters and steam boilers; reduce capital investment in wastewater treatment plants of industrial sewage systems, in particular, in settling tanks and saline waste collectors, due to the recycling of potassium chloride in the production cycle of boiler plants, as well as reduce the costs of wastewater treatment by recycling potash chloride as fertilizer, with almost no loss.

Technical and economic effect from the implementation of the proposed method on the installation capacity of 100 when the salt content of the source water 400 mg / l is approximately 6-7 thousand rubles in year. . ..

Claims (1)

METHOD FOR WATER SOFTENING, including passing it through a cation exchange filter, regenerating the latter with a metal chloride solution and treating the spent regeneration solution with a chemical reagent for precipitation of hardness ions, characterized in that, in order to create a drainless technology by making it possible to use the resulting effluents as mineral fertilizers , regeneration is carried out with a solution of potassium chloride, and as a chemical reagent for ion deposition - stiffnesses use alkaline potassium wastewater blowdown steam boilers fed K-cationic water,