CZ304788B6 - Method of determining biodegradation of inorganic building material by chemoorganotrophic microorganisms - Google Patents

Abstract

In the present invention, there is disclosed a method of determining biodegradation of inorganic building material by chemoorganotrophic microorganisms characterized in that samples of inorganic building material are put into a control medium, which contains a carbon-free mineral solution and in a medium infected by chemoorganotrophic bacteria containing the carbon-free mineral solution with addition of a soil extract prepared from compost soil or soil in the vicinity of which a structure of inorganic building material to be analyzed is situated wherein said inorganic building material must contain at least 10e6 microorganisms per 1 ml of the extract, whereby in the course of at least 5 and at the most 7 days concentration of Cae2e+ is measured each day with respect to the check samples added with the medium pH value and resisExciter for tance of the inorganic building material samples is thus determined from the obtained values. The inorganic building material is represented by concrete, sandstone, limestone and sandy marl.

Description

Technical field

The invention relates to a method for the rapid determination of the biodegradability of an inorganic building material, in particular concretes and possibly other building materials (marl, sandstone, limestone) of chemoorganotrophic microorganisms.

BACKGROUND OF THE INVENTION

The methods used so far mainly deal with sulfate corrosion, which has been studied very intensively in terms of damage to concrete structures due to natural and industrial wastewater. In this respect, a number of test methods have been developed, eg ASTM C1013 (1989) accelerated test with sodium or magnesium sulfate, as well as an accelerated test with sulfuric acid. These methods are able to describe the degree of concrete degradation in individual aggressive environments.

The resistance of various types of concrete was also monitored with regard to the influence of microorganisms. Even in this respect, simé bacteria were studied in particular and a number of different fermenters were developed in which the course of biocorrosion was monitored on various types of concrete rings of sewer collectors, mostly in dependence on time. Recently, however, it appears that the corrosion activity of simé bacteria has been overestimated in concrete structures (not in sewage collectors). Corrosion changes are probably influenced mainly by the direct transformation of sulfur dioxide to H2SO4 and not exclusively by the corrosive activity of simulated bacteria. Thion bacteria, however, continue to be found on concrete structures, but in the community of a number of other microbes (desulfurizing, denitrifying, nitrifying, ammonizing bacteria), in which they mostly do not play a dominant role.

However, the study of biodegradation in fermenters loses its meaning if concrete resistance in soil or atmospheric conditions is to be determined. Chemoorganotrophic microorganisms, which develop on the surface unevenness of damp concrete, develop on the earth, dirt and dust particles. The methodology, which in a simple way and without demanding analytical operations affected the corrosive effect of these organisms, has not been elaborated yet, although the synergistic effect of chemoorganotropic bacteria on sulfate corrosion is known and repeatedly mentioned in the relevant publications.

SUMMARY OF THE INVENTION

The above drawbacks are eliminated by a method for determining the biodegradation of inorganic building material by chemoorganotrophic microorganisms according to the invention, which consists in placing samples of the inorganic building material in a control medium containing a carbonate-free mineral solution and in a medium infected with chemoorganotrophic bacteria mineral solution with the addition of a soil extract prepared from compost ground or from soil in the vicinity of which the analyzed construction of inorganic building material is located. The medium infected with chemoorganotrophic bacteria must contain a minimum of 10 ⁶ microorganisms per ml of extract, measured over a minimum of 5 days and a maximum of 7 days against Ca ²⁺ controls supplemented with the pH of the environment, and the resistance of inorganic building material samples measured.

The inorganic building material (concrete) samples are preferably placed in a control medium containing a carbonate-free mineral solution protected by the addition of Ajatin, and in a medium infected with chemoorganotrophic bacteria, which contains a carbonate-free mineral solution with a single addition of 0.005 wt. peptone, based on 100 ml of mineral solution and with the addition of soil extract prepared from compost ground or from soil in the vicinity of the concrete structure to be analyzed, which must contain at least 10 ⁶ microorganisms per ml of extract, per ml of extract, per each 100 ml of mineral solution, and with daily additions of 0.02 wt. glucose based on 100 ml of mineral solution and, for a minimum of 5 days and a maximum of 7 days, the Ca ²⁺ concentration supplemented with the pH of the environment infected with chemoorganotrophic bacteria is measured from the measured values and the resistance of the inorganic building material the Ca ²⁺ concentration exceeds 10% in the infected environment, compared to the control environment by 10% and the pH of the infected environment decreases by more than two degrees, the given inorganic building material is resistant to biological corrosion caused by chemoorganotrophic bacteria.

The carbon-free mineral solution contains KH ₂ PO ₄ 0.1 g, K ₂ HPO ₄ 0.1 g, MgSO ₄ 0.3 g, (NH ₄ ) ₂ SO ₄ 0.5 g FeSO ₄ feet, in 1000 ml distilled water, is adjusted to pH 7.5 with 0.1N KOH.

The invention is based on the finding that chemoorganotrophic bacteria cause acid corrosion, which is known both in chemical plants and in agriculture. In damp constructions of inorganic building material, bacteria form acetic, formic, propionic, citric, gluconic, oxalic and many other tricarbonic acids. Since acids react primarily with Ca (OH) ₂ and later with Ca hydrosilicates and hydroaluminates to form lime salts, it is clear that the corrosion rate of inorganic building material, especially concrete, will depend mainly on the solubility of these Ca salts and the layer behavior of the resulting corrosion products. . The corrosion progresses faster the more soluble the reaction products formed and the faster they are washed out of the inorganic building material mass during the condensation of water vapor. Inorganic building materials are mainly concrete, sandstone, limestone and marlwood.

The embodiment is shown in the following example.

Exemplary embodiment

The size of the concrete samples depends on the size of the test vessels. Dimensions 50x50x50 mm to 100x100x100 mm are recommended, but other (larger) test specimen sizes may be used. It is essential that both control and test specimens must be the same as well as the test vessels and the volume of the control and test, infected environment in which the specimens must be completely immersed. The ratio of test volume to volume should be 1:10.

Aging of fresh concrete samples (lowering the pH of the concrete leach to 8) is done by boiling with 2N HCl or multiple exposure of the concrete in an autoclave at 120 ° C for at least 2 hours. If samples that have already been exposed to the site under soil or atmosphere conditions are tested, an additional aging is usually not necessary. However, it is recommended that the pH of the aqueous leachate of the concrete should not be higher than 8 before testing.

The soil extract for the inoculation of the test medium infected with chemoorganotrophic bacteria shall be prepared either from compost ground if the test is carried out on newly developed concretes or from soil in the vicinity of the structure to be analyzed. For the preparation of the soil extract, sieve treated with a grain size of 2 mm is used. Weigh 1 g of treated earth into 100 ml of distilled water. After mixing, the suspension is allowed to settle and filtered through a sintered glass crucible, size 2 to 3. In poor and sandy soils, the amount of bacteria in 1 ml of extract is estimated under a fluorescent microscope. Acridine orange solution (1:10 000 dilution) is used to distinguish living and dead bacteria, and living microbes fluoresce green. For composting ground, omice and grass soils, this preparation is not required.

The following carbon-free mineral solution is used as the control medium:

-2GB 304788 B6

KH ₂ PO ₄ 0.1 g, K ₂ HPO ₄ 0.1 g, MgSO ₄ 0.3 g, (NH ₄ ) ₂ SO ₄ 0.5 g, FeSO ₄ traces, distilled water 1000 ml, to pH 7, 5, the soil was treated with 0.1N KOH. Its sterility is maintained by the addition of Ajatin.

Inoculation of the entire test kit (containers, samples, environment) infected with chemoorganotrophic bacteria is performed depending on the volume of the medium. Use 1 ml of soil extract per 100 ml medium. 0.02 wt. glucose and 0.005 wt.% peptone as a growth starter. Control medium is not inoculated, peptone and glucose are not added, and sterility is maintained by addition of Ajatin. The addition of glucose to the test kit imitates an easily accessible carbon source.

Both control and test assemblies are placed in a thermostat. Culture temperature 27 ± 2 ° C, test time 5 to 7 days. During the test, 0.02 wt. glucose. No further inoculation is performed.

Throughout the exposure period, either ion-selective electrodes or colorimetric Ca ²⁺ concentrations in both environments are measured daily. At the same time, the pH of the medium is determined potentiometrically. If the Ca ²⁺ concentration in infected subjects exceeds 10% compared to the control samples and the pH of the medium drops by more than two degrees, the concrete is resistant to biological corrosion caused by chemoorganotrophic bacteria.

Industrial applicability

The method of determining the biodegradation of inorganic building material by chemoorganotrophic microorganisms is useful for determining the biodegradation of sandstone, limestone and marlwood concrete. It is particularly useful in the construction industry.

Claims (4)

PATENT CLAIMS Method for determining biodegradation of inorganic building material by chemoorganotrophic bacteria, characterized in that samples of inorganic building material are introduced into a control medium containing a carbon-free mineral solution and into a medium infected with chemoorganotropic bacteria which contains a carbon-free mineral solution with the addition of a soil extract compost earth or the ground, in which is close to the analyzed structure of the inorganic building material, which must contain at least 10 ⁶ microorganisms per 1 ml of the extract, during which a minimum of 5 and maximum of 7 days was measured each day over the control concentration of Ca ²⁺ supplemented o The pH of the environment and the measured values determine the resistance of inorganic building material samples. Method according to claim 1, characterized in that the inorganic building material samples are placed in a control medium containing a carbonate-free mineral solution protected by the addition of Ajatin and into a medium infected with chemoorganotrophic bacteria which contains a carbonate-free mineral solution with 0.02% daily additions wt. % glucose and a single addition of 0.005 wt. peptone, based on 100 ml of mineral solution and with the addition of 1 ml of soil extract per 100 ml of mineral solution prepared from compost ground or soil, in the vicinity of which is the analyzed construction of inorganic building material containing at least 10 ⁶ microorganisms per ml of extract, whereas during a minimum of 5 days and a maximum of 7 days, the Ca ²⁺ concentration supplemented with the pH of the environment is measured every day against control sterile samples, and the measured values determine the resistance of inorganic building material samples so that if the Ca ²⁺ concentration exceeds the infected samples of 10% and the pH of the medium decreases by more than two degrees, the given inorganic building material is resistant to biological corrosion caused by chemoorganotrophic bacteria. -3 CZ 304788 B6 Method according to claims 1 and 2, characterized in that the carbon-free mineral solution contains KH ₂ PO ₄ 0.1 g, K ₂ HPO ₄ 0.1 g, MgSO ₄ 0.3 g, (NH ₄ ) ₂ SO ₄ , 5 g, FeSO ₄ feet, in 1000 ml of distilled water, and adjusted to pH 7.5 with 0.1N KOH. The method according to claims 1 to 3, characterized in that the inorganic building material is concrete, sandstone, limestone and marl.