RU1832118C - Method of biological sewage treatment - Google Patents

Abstract

The inventive wastewater containing inorganic nitrogen compounds and organic nitriles before treatment with nitrifying microorganisms under aerobic conditions, a source of sulfide ion, a salt of hydrogen sulfide, is introduced.

Description

The invention relates to methods for purifying nitrogen-containing wastewater, including a nitrification step, and can be used in chemical plants.

An object of the invention is to increase the oxidation rate in the treatment of wastewater containing inorganic nitrogen compounds and organic nitriles.

The goal is achieved in that a source of sulfide ions in the form of salts of hydrosulfuric acid is introduced into the waste water containing ammonium nitrogen and acrylonitrile and subjected to biological oxidation by nitrifying microorganisms under aerobic conditions. The amount of sulfide ions introduced is determined by a production experiment with each specific biocenosis of activated sludge from the minimum time for blocking the nitrification process, since it is impossible to determine the percentage of removal of the cyano group in the form of HCN by analytical means.

In this technical solution, the amount of input sulfide ions is

predominantly 1 mol per 1 mol of acrylonitrile.

A comparative analysis of the claimed solution with the prototype shows that the claimed method differs from the known one in that the process is carried out in one step, and sulfide ion in the form of salts of hydrogen sulfide is introduced to detoxify acrylonitrile, while the oxidation rate of the nitrification process is significantly increases.

Example 1. Activated sludge containing nitrifying microorganisms, the total concentration of which on a dry matter was 3.5 g / l, a source of ammonium nitrogen, was introduced into a cell aerated at 25 ° C and equipped with an ion-selective electrode 3M-NH4-01. in the form (at a concentration of N-NH43 100 mg / l, and the kinetic curve of the biological nitrification of ammonium ions is taken (see drawing, curve 1). The obtained curve is a control curve. Under such experimental conditions, the oxidation rate of ammonium nitrogen is 51.4 mg / Nr h

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Example 2. The conditions of the experiment of Example 2 are similar to the experimental conditions of Example 1, but an additional 50 mg / L of acrylonitrile is added and the kinetic oxidation curve of ammonium ions is taken (see curve 2). From the course of the N-MSC oxidation curve, it follows that acrylonitrile is an inhibitor of the nitrification process, since the rate of ammonia nitrogen oxidation in the straight portion of the curve is reduced to 9.14 mg N g h compared to the control.

Example 3. The experimental conditions of Example 3 are similar to the experimental conditions of Example 1 with an additional addition of 20 mg / L sodium sulfide. From the presented kinetic curve of the oxidation rate of N-NH4 (see drawing, curve 3), it is seen that the effect of sodium sulfide is characterized by reverse blocking of the enzyme systems. Blocking continues until the sulfide ion is oxidized to forms of less than $ 20g, 5Oz2, SaOe2 or SO42 for microorganisms. At the same time, the oxidation rate of ammonium nitrogen first reaches 31.7 mg N g h, then it coincides with a control rate of 51.4 mg N g h.

Consequently, under these experimental conditions, 20 mg / L sodium sulfide blocks the enzymes of nitrifying microorganisms for 14.8 minutes, then becomes toxic.

Example 4. The experimental conditions of Example 4 are similar to those of Example 3, only the concentration of sodium sulfide introduced is increased to 50 mg / L.

From the course of the kinetic oxidation curve of N-NH4 + it follows that the blocking time of the nitrification enzyme systems increases to 44.2 minutes. after which the rate of nitrification from the beginning of the process increases from 30.4 m N g h to 51 mg N g g

Example Example 5 is similar to examples 3, 4, but the concentration of sodium sulfide is increased to 75 mg / l;

From the presented kinetic curve of the oxidation rate of N-NH (see the drawing, curve 5} it is seen that the blocking of enzyme systems of nitrification lasts 66.5

min, after - the inhibitory effect decreases, because the nitrification rate initially increases to 21.4 mg N g h, then coincides with the control, equal to 51.4 mg

NT -h

Example 6. The experimental conditions of example 6 are similar to the experimental conditions of example 1, only additionally simultaneously add 50 mg / l of acrylonitrile and 75 mg / l of sodium sulfide, i.e. in a ratio of 1 mol C3H3M: 1 mol Naz.S and the kinetic oxidation curve of ammonium ions is also taken. From the course of the N-NH oxidation curve (see Fig. Curve 6), it is seen that in the presence of sulfide ions, the toxicity of acrylonitrile for nitrifiers is significantly reduced. At the same time, detoxification of the sulfide itself occurs, due to the mechanism described in the description.

Moreover, the blocking of nitrification enzymes lasts only 12 minutes, in contrast to 66.5 minutes under the influence of 75 mg / L sodium sulfide alone. The rate of oxidation of ammonia nitrogen is reduced by only 62% and

19.5 mg // g / h. in contrast to the simultaneous action of acrylonitrile, which reduces the oxidation rate of ammonium ions by 82%.

The proposed method of wastewater treatment

waters containing acrylonitrile, compared with the prototype will allow:

-increase the oxidation rate of the nitrification process by 4 times;

- detoxify two poisonous components. - acrylonitrile and sulfide ion;

Claims (1)

- carry out the process in one stage. SUMMARY OF THE INVENTION Method for biological wastewater treatment water containing inorganic nitrogen compounds, including treatment under aerobic conditions with nitrifying microorganisms, characterized in that, in order to increase the rate of oxidation during the treatment of wastewater containing organic nitriles, a source of sulfide ion is introduced into the wastewater before treatment with nitrifying microorganisms - hydrochloric acid, CV-A / NjjMr / A with " ID eo 80 40 to " tO 20 30 50 € 0 TO 90 .KB. "D TO" 0 130 -t.MM