CS257060B1 - A method for removing volatiles from water and aqueous solutions - Google Patents

Abstract

The method of removing volatile substances from water and aqueous solutions by distillation consists in the fact that the distillation takes place at total reflux while simultaneously blowing in a gaseous inert carrier medium, for example air or carbon dioxide, while the carrier medium with volatile substances moves through the dephlegmator at a speed of from 0.01 ms"l to 10 ms"l, preferably 0.5 ms"l.

Description

The invention relates to a process for the removal of volatiles from water and aqueous solutions.

Volatile materials such as ammonia, hydrogen sulfide, hydrogen sulfide, various types of hydrocarbons, etc. are most often removed from the water by distillation or stripping with steam, air, inert gas, and the like. A number of factors influence the choice of a suitable method for removing volatile substances from water. The most important are the quantity and chemical composition of water, requirements for purified water, pressure, temperature and more.

During distillation, the liquid mixture is heated to boiling and the resulting vapors are removed and condensed after cooling. The result of distillation is water, depleted of volatile substances and condensate containing these substances in concentrated form. Depending on the type and proportion of volatile substances in the condensate, their distribution or isolation of some substances for further industrial use or their disposal, for example by thermal treatment, may follow. The volume of the condensate formed largely depends on the volatility of the substance to be separated and its water solubility. In such cases, where a considerable amount of water condensate is produced, distillation is disadvantageous.

Typically, the design of a distillation plant is based on the knowledge of the equilibrium values of the binary mixture: volatile substance - water and the verification of whether this equilibrium applies 1 to a particular type of waste water or other water.

An example of a calculation to ensure the number of theoretical plates of a distillation column used to remove ammonia from coke and gas waters is given in Hladký V., Hromada V., Burian V., (water management 5B, 1981, p. 129). The authors present a summary of technical-economic data relating to both the treatment of gas waters with an inlet ammonia concentration of 7 g.l and an outlet of 0.1 g.l at zero reflux ratio, i.e. the deamonification of this type of water with varying ammonia concentration using different reflux ratio. This work is immediately followed by Cs. Ao (Hladký V.) 191 755, C01C 1/10.

The distillation of ammonia from waste water is the subject of a number of patents, differing mainly in the construction of the distillation columns used. 429, C01 Cl / 10, Marrovic I .: DE 2 362 887, C01 Cl / 10.

In another work / Hubena J., Vejvoda J., Stepanek 1., Novak E .: Sewage sludge treatment from methane fermetation of wastes from pig feed. The results of experiments with distillation of ammonia from sludge water after methanization of manure from pig fattening are included. The research was initiated by patent / Krištoufck J .: Pr. Dem. FR 2 474 901 B 09 B 3/00

An example of a solution where, in addition to ammonia, other volatile substances are obtained by distillation is the removal of ammonia and chloroform from waste water from the production of herbicides / Manczak M., Kozakowsk P.: Gaz. Woda i Tech. Sanit. 57, 5, 1983, pp. 145].

A solution enabling the gradual distillation of ammonia and hydrogen sulphide from waste water is contained in the patent / Anonymous: Jpn Kokai Tokkyo Koho J / 60,114,389, C 02 F 1/04.

The distillation is also used to remove ammonia and methanol from the effluents / Callahan JL, Hardman HF, Grasseli RK: Ger. Offen 2 331 139 or phenol next to ammonia / Psakhis Β. I., Popov A.V., Leontjevskij V.G., Bogdanov A. I., Vinogradov J.V., Malchov V.M.: Su 960 128, C 02 F 1/20.

The recovery of fluorides in addition to ammonia by the distillation of wastewater is made possible by the patent [Kosumoto T., Negishi H., Honma T .: Jap. Kokai 7,785,095 Cl C 02 5/02.

One of the main drawbacks of distillation used to remove volatiles from water and aqueous solutions - the large amount of water condensate is eliminated by the method of the present invention, which involves the continuous stripping of volatile vapors with a gaseous inert medium supplied above the surface. heated water or aqueous solution, wherein the carrier medium with the volatiles is moved at a rate of 0.01 ms to 10 ms, preferably 0.5 ms, and the distillation is carried out at total reflux. The volatile substances removed from the still by the gaseous medium are collected in the absorption solution or on the adsorbent.

An advantage of the proposed method of removing volatiles from water and aqueous solutions is that large volumes of condensate are not formed at the same time. Another advantage is that the volatile components are obtained in a concentrated form, facilitating their use. Compared to stripping, the required amount of carrier medium is considerably lower.

The method of the invention is further described by way of example.

Example 1

The proposed solution was used in the removal of ammonia from wastewater from the rendering plant.

Air supplied in an amount providing a vapor flow rate of 0.5 ms ¹ was used as the carrier medium for the removal of ammonia vapors from the effluent whose pH was adjusted to 11.5 by alkalization to 11.5. Ammonia gas was collected in a sulfuric acid solution. The course of ammonia removal was analyzed analytically and the results are summarized in the following table:

T a b at 1 k a

Dpba distillation NH3 content pH ^{/ minJ /} mg.ΐΛ

0 2 100 11.5 10 1 700 - 20 May 780 - 30 412 - 40 250 - 50 174 - 60 100 ALIGN! 9.45

Example 2

A standard ammonium chloride solution having a concentration of NH 4 1035 mg.l and a pH of 11.5 was subjected to distillation in September equipped with a def Legmator and a supply of compressed air resulting above the level of the heated solution. Upon reaching the boiling point of the solution, air vapor removal was performed. The vapor flow rate in the demegulator was 0.1 m.s. The stripped ammonia was collected in sulfuric acid. The results of the continuous study are shown in Table II.

Claims (2)

1. A process for the removal of volatile substances from water and aqueous solutions by distillation, characterized in that the distillation is carried out at total reflux while injecting a gaseous inert carrier medium such as air or carbon dioxide, wherein the carrier medium with volatile substances moves at ¹ to 10 ms ^-1 , preferably 0.5 ms ^-1 . 2. A method according to claim 1, characterized in that the carrier medium is supplied above the surface of the heated water or aqueous solution. Severography, n. P., MOST