RU2024079C1 - Method of bilogical treatment of liquids from radionuclides and heavy metals and strain of fungus aspergillus niger bkmf-33 used for biomass preparing extracting radionuclides and heavy metals from liquids - Google Patents

Abstract

FIELD: applied microbiology. SUBSTANCE: method of liquids treatment from radionuclides and heavy metals involves treatment of these liquids with sorbent in the form of fungal biomass. Biomass of fungi of species Aspergillus niger, mainly biomass of strain of fungi Aspergillus niger, BKMF-33, is used as sorbent. EFFECT: improved method of treatment. 3 cl, 4 tbl

Description

 The invention relates to applied microbiology and can be used for biological treatment of radionuclides and heavy metals from wastewater, liquid radioactive materials after preparing solutions containing radionuclides and heavy metals from them.

 A known method of purifying liquids from uranium and thorium, including the use of the biomass of the fungus Rhizopus arrhizus as a sorbent [1].

 The disadvantage of this method is that it does not provide for the cleaning of solutions from other radionuclides and from heavy metals.

 A known bacterial strain Pseudomonas aeruginosa, the biomass of which is used as a sorbent for cleaning liquids from radionuclides (uranium and thorium) [2].

 A disadvantage of the known strain is the lack of information about the possibility of using its biomass to extract other radionuclides from liquids, as well as heavy metals.

 The purpose of the invention is to increase efficiency by expanding the spectrum of radionuclides and heavy metals removed from liquids and reducing their residual content in the treated liquid.

 The aim of the invention is also to expand the range of fungal strains whose biomass effectively removes a wide range of radionuclides and heavy metals from liquids.

 The goal is achieved in that according to the method of purifying liquids from radionuclides and heavy metals, including treating liquids with a sorbent in the form of mushroom biomass, the biomass of Aspergillus niger species, mainly the biomass of the Aspergillus niger VKMF-33 mushroom strain, is used as the sorbent. This strain of fungi is deposited in the All-Union collection of microorganisms as a typical one (Catalog of microorganism cultures supported in USSR institutions. M: Nauka, 1981, p. 110).

 The following are examples of the implementation of the new method, illustrating the effectiveness of the application of the known strain of the fungus for a new purpose.

PRI me R 1. The studied strains of the fungus Aspergillus niger were stored on jambs of agarized wort at a temperature of +4 ± 1 ^о С with replanting on fresh jambs after 2-4 months. The accumulation of biomass of fungi used as a sorbent to remove radionuclides and heavy metals from liquids was carried out in several stages.

The culture was stored on the doorposts, replated on agar Czapek-Dox medium and incubated 48 h at 28 ° ^C. For the material ionokulyatsionnogo 48-hour culture were reseeded on Czapek-Dox medium of the following composition, g / l: glucose 30 NaNO _{3 January 2} K HPO ₄ 1 KCl 0.5 MgSO ₄ ^. 7H ₂ O 0.5 FeSO ₄ 0.01 Yeast extract 0.1
To prepare the medium, distilled water up to 1 liter was added to the listed components. Before sterilization with a 10% solution of H ₂ SO _{4, the} pH of the medium was adjusted to 5.5. The medium was sterilized at 121 ^{° C} for 30 min. The strain was incubated in Erlenmeyer flasks on a rotary shaker at 230 rev / min and a temperature of 28 ^{° C} for 48-60 hours. For inoculating material derived biomass was inoculated into the same medium in an amount of 5-6 volume and incubated for 48- 60 hours in Biotec fermentation apparatus under the following conditions: pH 5.5; aeration: two volumes air to one volume of the medium, with stirring at 500 rev / min at a temperature of 28 ^C. After completion of the fermentation cycle, the biomass was separated by centrifugation, washed with distilled water and used as a sorbent for the removal of radionuclides and heavy metals from liquids.

 PRI me R 2. The fungus was grown as in example 1 and then compared the effectiveness of the use of biomass of different strains of the species Aspergillus niger to remove radionuclides contained in the presence of heavy metals from solutions of their salts.

The sorbing properties of the biomass of three strains of Aspergillus niger were studied by the example of purification of specially prepared individual solutions of ⁹⁰ Sr, ¹³⁷ Cs, ²³⁹ Pu and solutions of their mixture with the addition of heavy metal ions (Fe, Ni, Cr, etc.). A known amount of radionuclides and heavy metals was added to the biomass suspension and then shaken on a rocking chair at a frequency of about 250 times per minute for 2 hours, then the biomass was separated by centrifugation.

 The content of radionucdides and heavy metals in the solutions purified from them was determined before and after treatment of the solutions with a sorbent - biomass of fungi of the species Aspergillus niger.

, где А_нач и А_кон - полная активность данного радионуклида в водной фазе до и после биосорбции соответственно, Бк;
W - масса сухого вещества в данном образце биосуспензии, г.For convenience of comparison, in all experimental variants, model solutions of ⁹⁰ Sr, ¹³⁷ Cs, ²³⁹ Pu chlorides with a specific activity of each element of about 107 Bq / l were subjected to purification from radionuclides and heavy metals. The results are shown in tables 1 and 2, in which the following notation:
With _con - the concentration of the corresponding radionuclide in the solution after biosorption, Bq / l;
K is the distribution constant of the radionuclide between the aqueous phase and biomass, l / g. Dry weight. The value of the distribution constant was determined from the expression
K =

where A _beg and A _con are the total activity of a given radionuclide in the aqueous phase before and after biosorption, respectively, Bq;
W is the dry matter mass in this biosuspension sample, g.

· 100% .To characterize the completeness of extraction of radionuclides from the aqueous phase, their degree of extraction was calculated
ϒ =

· 100% .

The data presented in Tables 1 and 2 show that the biomass of all tested strains of the Aspergillus niger species is an effective sorbent for removing individual radionuclides and their mixtures from solutions, including in the presence of heavy metals. The most effective is the biomass of the strain Aspergillus niger VKMF-33. It should be noted that sorption occurred from ultra-diluted solutions of radionuclides (the equilibrium concentration for ⁹⁰ Sr was of the order of 10 ^-8 g / l or less, for ¹³⁷ Cs - ≅ ^10-6 g / l, for ²³⁹ Pu - ≅ 10 ^-4 g / l ), which indicates an extremely high chemical affinity of biological structures of the studied species of microorganisms to ⁹⁰ Sr, ¹³⁷ Cs and ²³⁹ Pu.

 PRI me R 3. A comparison of the effectiveness of the use of biomass of the fungus Aspergillus niger species for the purification of liquids from radionuclides and heavy metals and biomass of other studied types of microorganisms. The results are presented in table 3 and indicate the highest biomass efficiency of the fungus Aspergillus niger.

PRI me R 4. As an object of purification was used an aqueous solution of chlorides ⁹⁰ Sr, ²³⁷ Cs and ²³⁹ Pu with an initial concentration of 9.96 ^. 10 ⁵ Bq / l, 5.93 ^. 10 ⁶ Bq / l and 4.21 ^. 10 ⁴ Bq / l, respectively. In addition to the indicated radionuclides, FeCl _{3 was} contained in the liquid being cleaned, thus, in addition to plutonium, the system contained ions of another heavy metal — Fe ³⁺ with a concentration of 7.5 mg / L. Purification of the initial solution was carried out by the biomass of the strain Aspergillus niger VKMF-33. The cleaning procedure was as follows. Crude biomass of Aspergillus niger VKMF-33 strain was added to the liquid to be purified at the rate of about 10 cm ^{3 of} biomass per 100 ml of liquid. The resulting biosuspension was stirred on a circular shaker for 30 minutes with a frequency of about 240-250 vibrations per minute. Upon completion of this operation, the biosuspension was filtered. After sampling for analysis, the liquid to be purified was subjected to repeated purification by a similar method. It should be noted that already after the first purification cycle, iron in the aqueous phase was present in trace amounts (less than 1 mg / l). The final phase (third cycle) of purification was the passage of the solution obtained after two cycles of sorption through a layer of crude biomass of the strain Aspergillus niger VKMF-33 (layer thickness 25-30 mm). The biomass was in a column at the bottom of which a bacterial filter was installed. Liquid was passed through the filter at a rate of about 1 ml / h.

 The experimental results are shown in table 4.

 As can be seen from the data presented, despite the presence of ferric iron ions in the initial solution, it was possible to clear radionuclides by 96.1% or more.

Claims (2)

 1. The method of biological purification of liquids from radionuclides and heavy metals, including the treatment of liquids with a sorbent in the form of mushroom biomass, characterized in that Aspergillus niger mushroom biomass is used as a sorbent.  2. The strain of the fungus Aspergillus niger BKMF-33, used to obtain biomass that extracts radionuclides and heavy metals from liquids.

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