SU1746878A3 - Method of two-stage biological neutralization of sewage - Google Patents

Abstract

Use: pulp and paper, food processing, microbiological industries. SUMMARY OF THE INVENTION 1 In the first stage, wastewater treatment is carried out in the presence of the microorganisms of the yeast Candida and p. Trichosporon with an additional supply of purified water at this stage in the amount of 10-30% of the total volume of the flow, then fed to the second stage, where the source wastewater is additionally introduced in the amount of 10-20% of the total volume of the flow. The use of the invention allows to increase the degree of purification by 10-15%, to increase the yield of feed bioamess by 5-10%, to increase the protein content in the feed product by 3-4%. 3 tabl,

Description

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The invention relates to methods for biological treatment of wastewater containing high concentrations of organic substances such as carbohydrates, proteins, organic acids and others, and can be used in the pulp and paper, food and microbiological industries.

There is a known method of biological wastewater treatment, in which sulphite lye or hydrolyzate is used at the first stage, and a post-yeast brew is used at the second stage. At the first stage of purification, mainly sugars are contained in the substrate, and at the second stage organic acids and metabolites (amino acids, organic acids, proteins, etc.) are removed.

The disadvantage of this method is that the metabolites, which stimulate the growth of microorganisms, pass to the second stage and, as they accumulate, are removed from the environment, in connection with

than can not be used by microorganisms in the cleaning process in the first stage.

There is a known method of biological treatment of wastewater in aeroshells using activated sludge, where, to accelerate the treatment process, an extract of hydrolyzed excess activated sludge is introduced into the wastewater as a biostimulator.

The disadvantage of this method is the need for additional costs for hydrolysis of activated sludge. In addition, since activated sludge microorganisms have the ability to concentrate various toxic substances contained in wastewater, the return of sludge can lead to an increase in the maximum allowable doses of these substances in treated effluents.

The closest in technical essence to the proposed method is a two-step biological treatment method.

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wastewaters containing high concentrations of organic matter by oxidizing them in the first stage with yeast p. Candida mixed with yeast r. Trlchosporon or mycelial fungi, and at the second stage - by microorganisms after the first stage of purification.

The advantage of this method is the possibility of carrying out the purification process in the first and second stages with microflora adapted to this substrate, which allows to intensify the process and at the same time obtain a marketable product in the form of fodder yeast. ,

The disadvantage of this method is that the intensification of the cleaning process is carried out only through the use of specific microflora.

As studies conducted showed, during their growth at the first stage of purification, the microorganisms used are released into the medium as metabolites in the form of organic acids, amino acids, proteins and other products that can stimulate the growth of microorganisms secreting them.

However, in flow cultivation, which includes biological purification, these metabolites are removed from the first stage together with the purified substrate to the second stage and are not used to intensify the cleaning process in the first stage.

At the same time, in the second stage, the content of metabolites is too high due to their entry from the first stage and the formation of additional metabolites in the second stage. Excess metabolites in the second stage, as studies have shown, reduce the physiological activity of microflora, which performs purification in the second stage.

The purpose of the invention is to increase the degree of purification and increase the yield of feed biomass.

For the implementation of the method, the first stage of biological treatment additionally supplies wastewater that is purified in the first stage and contains metabolites in an amount of 10-30% of the total flow volume, which plays the role of a bio-stimulator, and initial wastewater in an amount of 10-20% is added to the second stage total runoff.

The method is carried out as follows.

Wastewater with a hydrocarbon content of from 0.05 to 2.5% and BPKB - 2500-25000 mg / l with the addition of the required amount of nutrient salts of nitrogen and phosphorus is fed to the first purification stage in an aerated fermenter with a volume of 320, 600 and 1260 m in an amount of 20 -25% of the working volume of the fermenter.

An association is introduced into the fermenter.

yeast containing yeast microorganisms p. Candida and p. Trichosporon, carrying out the process of purification and biomass synthesis, in the amount of 0.5-1.0 g / l (dry matter basis).

0 Wastewater is aerated in contact with biomass until the concentration of microorganisms reaches 2.5-4.0 g / l, after which the liquid volume in the apparatus is maximized, and the cleaning process begins with continuous flow and biomass collection. The cleaning process in the first stage is carried out at a temperature of 36-39 ° C and an initial pH of 4.1-5.0. In the future, the pH of the medium is not regulated.

0 Biomass is separated from the purified effluent by any method and sent for drying. The wastewater after the first stage is sent to a collection, from where a part of the purified effluent (10-30%) is directed as

5 source of metabolites, to the first stage, and the rest of the drain is fed to the second stage, where 10-20% of the initial runoff are simultaneously introduced in order to dilute and eliminate the inhibitory effect of metabolites

0 at the second stage of cleaning.

At the second stage, the biomass after the first stage of purification is used as the working microflora, which is introduced once, and then its amount is maintained at the expense of its own growth. Excessive biomass is continuously removed from the fermenter, separated from the purified effluent by any method, and served for drying together with the first-stage biomass. Common

0, the duration of cleaning in the first and second stages is 1.5-2.0 hours, and the growth time of the biomass is 3-4 hours.

Example 1. Sulfite liquor with BOD5 - 20000 mg / l (48.0 tons / day) is fed to the first

5 steps of purification in a 600 mu mutation in the amount of 100 m3 / h and 10 m3 / h (10%) of purified effluent from BODe - 8050 mg / l (19.32 t / day) are added. Total tonnage of organic substances entering the first The stump is 49.93 tons / day.

A one-time association of the yeast used for refining is introduced into the fermenter. The initial concentration is 1 g / l (dry basis). Purification is carried out at 365 39 ° C and an initial pH of 4.3-4.5.

The biomass obtained at the first stage of purification is separated from the purified effluent and is fed for drying.

Purified stock with the original BODC - 8050 mg / l is fed to the second cleaning stage.

in the amount of 100 m3 / h and add 10 m3 / h (10%) of the initial flow entering the first stage with BPKb - 20,000 mg / l. The total tonnage of organic matter entering the second stage is 23.77 tons / day. Cleaning at the second stage is carried out at 36-39 ° C. Purified wastewater is separated from biomass, which is processed together with first-stage biomass.

The total cleaning effect after two steps is at least 80%.

In tab. Figures 1 and 2 present data on the effectiveness of the cleaning process in the first and second stages, depending on the process parameters in comparison with the known method.

Introduction of less than 10% and more than 30% of the purified runoff to the first stage of purification, as well as less than 10% and more than 20% of the source flow to the second stage of purification leads to a decrease in the degree of purification and biomass growth.

In tab. 3 presents comparative data on the effectiveness of cleaning processes and the yield of feed biomass by known and proposed methods.

Using the proposed method allows increasing the degree of purification of wastewater containing high concentrations of organic substances by 10–15%, increasing the yield of feed biomass by 5–10%, increasing the protein content in the feed product by 3–4%.

Claims (1)

Invention Formula The method of two-stage biological wastewater treatment, including treatment at the first stage in the presence of yeast microorganisms p. Candida and r. Trlchosporon, feed to the second stage, followed by separation of purified water and feed biomass, characterized in that, p. In order to increase the degree of purification and increase the yield of forage biomass, the first stage additionally supplies purified water at this stage in the amount of 10-30% of the total flow volume, and the initial stage additionally introduces initial wastewater in the amount of 10-20% of the total flow volume. Table I table 2 Table 3