Phosphorus, total and phosphates. Phosphates - where are you from and why? About the most common chemical compounds
Download document
FEDERAL SERVICE FOR ENVIRONMENTAL,
TECHNOLOGICAL AND NUCLEAR SUPERVISION
QUANTITATIVE CHEMICAL ANALYSIS OF WATER
MEASUREMENT TECHNIQUE
MASS CONCENTRATIONS OF ORTHOPHOSPATES,
polyphosphates and total phosphorus in
DRINKING, NATURAL AND WASTE WATER
PHOTOMETRIC METHOD
APPLICATION AREA
Real normative document establishes a method for the photometric determination of polyphosphates, total phosphorus and dissolved orthophosphates (phosphate ions) (in terms of RO 4) in samples of drinking, natural and waste water at mass concentrations:
Table 1
If the mass concentration of the determined indicator exceeds the upper point of the calibration curve, the analyzed sample is diluted.
If the mass concentration of the determined indicator in the analyzed sample exceeds the upper limit of the range of measured concentrations, then the sample can be diluted with distilled water so that the concentration of the determined indicator corresponds to the regulated range.
Determination interfere with hydrogen sulfide and sulfides in concentrations exceeding 3 mg/DM 3 . The interfering effect is eliminated by adding potassium permanganate to 100 cm 3 of the analyzed water in such an amount that, when shaken for 1–2 minutes, a slightly pink color remains. Then the reagents are added in the reverse order than indicated in the procedure: first, a solution of ascorbic acid is added, mixed, and a solution of a mixed molybdic acid reagent is added. Reagents are added in the same order in the presence of chromates at a concentration of more than 2 mg/dm 3 .
The interfering effect of nitrites is eliminated by adding sulfamic acid, which is part of the mixed molybdic acid reagent.
Arsenic, mercury, silicon interfere with the determination at concentrations of more than 5 mg/dm 3 , vanadium and copper at concentrations of more than 10 mg/dm 3 . The interfering effect of silicon is eliminated during the analysis due to the high acidity of the reagent used, as well as by diluting the sample before analysis. The influence of arsenic and metals can be neglected, since they are usually found in water at concentrations well below 10 mg/dm 3 .
1. ASSIGNED CHARACTERISTICS OF THE MEASUREMENT ERROR AND ITS COMPONENTS
1.1. This technique provides analysis results with an error not exceeding the values given in Table 2.
table 2
The values of the characteristics of the error and its components at a confidence level P = 0.95
Defined indicator |
Measuring range, mg/dm 3 RO 4 |
Repeatability index(standard deviation of repeatability), s r (d), % |
Reproducibility index(standard deviation of reproducibility), s R (d), % |
Accuracy rate(boundaries within which the error of the method is located), d, % |
Drinking and natural waters |
||||
orthophosphates |
||||
polyphosphates |
||||
phosphorus total. |
||||
Wastewater |
||||
orthophosphates |
||||
polyphosphates |
||||
phosphorus total. |
||||
1.2. The value of the accuracy indicator of the methodology is used for:
Registration of measurement results issued by the laboratory;
Evaluation of the activities of laboratories for the quality of testing;
Evaluation of the possibility of using the results of measurements in the implementation of the methodology in a particular laboratory.
2. MEASUREMENT METHOD
The method is based on the interaction of orthophosphates with ammonium molybdate in an acidic medium with the formation of molybdophosphoric acid, its reduction with ascorbic acid in the presence of antimony chloride, followed by photometric measurement of the blue-colored reduced form of molybdophosphoric acid (molybdenum blue) at a wavelength of 880 - 890 nm.
The determination of polyphosphates and total phosphorus is carried out after their preliminary hydrolysis and / or mineralization to orthophosphates. A flowchart for the analysis of dissolved orthophosphates, polyphosphates and total phosphorus is given in Appendix 1.
3.1.4. Protective screen for the mineralization reactor, made of polycarbonate, 4.5 mm thick and 37.5 cm high;
3.1.5. Volumetric flasks with a capacity of 50, 100, 1000 cm 3 according to GOST 1770, 2nd class of accuracy.
3.1.6. Pipettes with a capacity of 1, 2, 5 and 10 cm 3 according to GOST 29227, 2nd class of accuracy.
3.1.7. Pipettes with one mark with a capacity of 1, 2, 5 and 10 cm 3 according to GOST 29169, 2nd accuracy class.
3.1.8. Reactor for carrying out mineralization with cells for round cuvettes, providing a temperature of 120 ± 2 °C.
3.1.9. A spectrophotometer that provides measurements at a wavelength of 880 - 890 nm, equipped with an adapter for round cuvettes 16 × 100 mm.
3.1.10. Dark glass bottles with a capacity of 250, 500, 1000 cm 3 (for storing reagents).
3.1.11. Refrigerator household of any type, providing storage of samples at a temperature of 2 - 6 °C.
3.1.12. Measuring cylinder with a capacity of 100, 250 cm 3 according to GOST 1770, 2nd class of accuracy.
It is allowed to use other measuring instruments with metrological characteristics not worse than those of the above, and auxiliary devices with technical specifications no worse than the above.
Note : For washing crockery not allowed usage synthetic detergents funds.
3.2. Reagents And materials
3.2.1. Ammonium molybdate (ammonium molybdate), chemically pure according to GOST 3765 or according to TU 6-09-5086.
3.2.2. Ammonium persulphate (ammonium persulfate), analytical grade according to GOST 20478;
3.2.3. Ascorbic acid, analytical grade GF X FS 42-2668.
3.2.4. Distilled water according to GOST 6709 or demineralized according to ISO 3696 (2nd degree of purity).
3.2.5. Tartaric acid, analytical grade according to GOST 5817.
3.2.6. Sulfuric acid, chemically pure according to GOST 4204.
3.2.7. Sodium hydroxide (hydroxide), analytical grade according to GOST 4328.
3.2.8. Sulfamic acid, analytical grade according to TU 6-09-2437.
3.2.9. Antimony trichloride (antimony chloride), chemically pure according to TU 6-09-17-252.
3.2.10. Chloroform, chemically pure according to TU 6-09-4263.
3.2.11. Test tubes (cuvettes) 16×100 mm, round, with plastic screw caps.
3.2.12. Cotton napkins or paper napkins.
3.2.13. Glasses with a capacity of 150, 250, 1000 cm 3 according to GOST 25336.
3.2.14. Membrane filters with a pore diameter of 0.45 µm according to GOST 25336.
3.2.15. Ashless filters "blue tape" according to TU 6-09-1678-95. It is allowed to use reagents of a higher qualification, materials with technical characteristics no worse than those of the above or imported analogues.
4. CONDITIONS FOR SAFE WORK
4.1. When performing analyzes, it is necessary to comply with safety requirements when working with chemical reagents in accordance with GOST 12.1.007.
4.2. When working with the equipment, it is necessary to follow the electrical safety rules in accordance with GOST 12.1.019.
4.3. Training of workers in labor safety should be organized in accordance with GOST 12.0.004.
4.4. The laboratory room must comply with fire safety requirements in accordance with GOST 12.1.004 and have fire extinguishing equipment in accordance with GOST 12.4.009.
5. OPERATOR QUALIFICATION REQUIREMENTS
Measurements can be performed by an analytical chemist who is proficient in the technique of photometric analysis and has studied the operating rules of the equipment used.
6. MEASUREMENT CONDITIONS
When performing measurements in the laboratory, the following conditions must be met:
air temperature 20 - 28 °C
relative air humidity no more than 80% at 25 °С
AC frequency (50 ± 1) Hz
mains voltage (220 ± 22) V.
7. WATER SAMPLING AND STORAGE
7.1. Sampling is carried out in accordance with GOST R 51592-2000 “Water. General requirements for sampling” and GOST R 51953-2000 “Drinking water. Sample selection." Water sampling is carried out in glass or polyethylene bottles. The volume of the sample taken is not less than 250 cm 3 .
7.2. The shelf life of samples is not more than 24 hours after sampling at a temperature of 2 - 6 °C. If the determination is carried out on the day of sampling, then the sample is not preserved. If the sample is not analyzed on the same day, then it is preserved with chloroform at the rate of 2 - 3 cm 3 per 1 dm 3 of the sample. The canned sample is stored for up to five days at a temperature of 2 - 6 °C.
7.3. When sampling, an accompanying document is drawn up in the approved form, which indicates:
Purpose of analysis, suspected contaminants;
Place, time of selection;
Sample code;
Position, name of the person taking the sample, date.
8. PREPARATION FOR MEASUREMENTS
8.1. Training instrument
Preparation for operation of the spectrophotometer or photocolorimeter is carried out in accordance with the operating instructions for the operation of the device.
8.2. Cooking solutions
8 .2 .1 . Cooking solution ascorbic acids, 20 g/dm 3
In a volumetric flask with a capacity of 100 cm 3, dissolve 2.0 g of ascorbic acid in a small amount of distilled water and bring the volume of the solution to the mark with distilled water. The solution is stored at a temperature of 2 - 6 ° C for no more than 10 days.
8 .2 .2 . Cooking reagents, incoming in composition mixed molybdenum-sour reagent
8 .2 .2 .1 . Solution molybdate ammonium
Dissolve 12.5 g of ammonium molybdate in approximately 200 cm 3 of distilled water in a beaker.
8 .2 .2 .2 . Solution chloride antimony from wine acid
Dissolve 0.235 g of antimony chloride and 0.6 g of tartaric acid in approximately 100 cm 3 of distilled water in a beaker.
8 .2 .2 .3 . Solution sulfamic acids
Dissolve 10 g of sulfamic acid in approximately 100 cm 3 of distilled water in a beaker.
8 .2 .3 . Cooking mixed molybdenum-acid reagent
In a volumetric flask with a capacity of 1000 cm 3 pour 300 cm 3 of distilled water, pour 144 cm 3 of concentrated sulfuric acid with stirring. After cooling the resulting solution to room temperature, all the solutions prepared according to p.p. are completely poured into the same volumetric flask with stirring. 8.2.2.1 - 8.2.2.3. The volume of the solution in the flask was adjusted to the mark with distilled water.
The solution is stored in a dark glass bottle at room temperature for no more than two months.
8 .2 .4 . Cooking 0 ,5 mol / dm 3 solution sulfuric acids (0 ,5 M)
28 cm 3 of concentrated sulfuric acid (r = 1.84 g/cm 3 ) are carefully mixed with about 500 cm 3 of distilled water. After cooling, the volume of the solution is adjusted to 1000 cm 3 . Shelf life 6 months at room temperature.
8 .2 .5 . Cooking solution hydroxides sodium concentration 1 mol / dm 3 (1M)
In a heat-resistant beaker with a capacity of 1000 cm 3 carefully dissolve 40 g of sodium hydroxide in 500 - 600 cm 3 of distilled water with stirring. After complete cooling, the resulting solution is transferred into a volumetric flask with a capacity of 1000 cm 3, the volume of the solution is adjusted to the mark with distilled water. Shelf life of the solution is 6 months in a polyethylene bottle at room temperature.
Weighing and dissolution of sodium hydroxide is carried out in goggles, gloves, under traction!
8 .2 .6 . Cooking main solution phosphate-ions from concentration 100 mg/dm 3
The main calibration solution with a concentration of phosphate ions of 100 mg/dm 3 is prepared from a GSO ampoule in accordance with the instructions for its use. The shelf life of the solution is 6 months at a temperature of 2 - 6 °C.
8 .2 .7 . Cooking working solution (I ) from concentration phosphate-ions 10 mg/dm 3
In a volumetric flask with a capacity of 100 cm 3 pipette is placed 10.0 cm 3 of the stock solution of phosphate ions (100 mg/DM 3). The volume of the solution was made up to the mark with distilled water. The shelf life of the solution is 3 months at a temperature of 2 - 6 °C.
8 .2 .8 . Cooking working solution (II ) from concentration phosphate-ions 1 mg/dm 3
In a volumetric flask with a capacity of 50 cm 3 pipette placed 5.00 cm 3 of the working solution (I) of phosphate ions. The volume of the solution was made up to the mark with distilled water. The solution is used freshly prepared.
8.3. Establishment calibration characteristics
0.4, 1.0, 2.5, 5.0 cm 3 of the working solution (II) with a phosphate concentration of 1 mg / dm 3 and 1.0, 1.5, 2.0 cm 3 are sequentially poured into test tubes with screw caps 3 working solution (I) with a phosphate concentration of 10 mg/dm 3 . Distilled water is added to each test tube to a volume of 9.00 cm 3 - i.e. 8.6, 8.0, 6.5, 4.0 and 8.0, 7.5, 7.0 cm 3 respectively. Next, 0.5 cm 3 of a mixed molybdic acid reagent is added to the test tubes. Not earlier than after 2 minutes, add 0.5 cm 3 of ascorbic acid solution, close the tube with a screw cap and mix.
After 15 - 20 minutes, the optical density of the calibration solutions is measured relative to a blank sample at a wavelength of 880 - 890 nm:
Distilled water with the addition of all reagents is used as a blank sample.
The concentrations of orthophosphates in solutions when establishing the calibration characteristics are equal, respectively: 0.04 - 0.10 - 0.25 - 0.50 - 1.00 - 1.50 - 2.00 mg / dm 3.
Based on the measurement results, a calibration graph is built for the dependence of the optical density value (units abs.) on the concentration of orthophosphate ions (mg / dm 3) or, if the capabilities of the spectrophotometer allow, the data on the calibration characteristic is stored in the instrument's memory.
The control of the stability of the calibration characteristics is carried out by one calibration solution before each series of analyzes. The calibration characteristic is considered stable if the obtained value of the concentration of the calibration solution differs from the certified value by no more than 10%. If the stability condition for the calibration characteristic is not met for one calibration solution, it is necessary to perform a repeated measurement for this calibration solution in order to exclude the measurement result containing a gross error. If the calibration dependence is unstable, find out and eliminate the causes of instability and repeat the control using at least 2 other calibration solutions provided by the method. When a deviation of the result is detected again, a new calibration characteristic is built.
The calibration characteristic is re-established when changing the batch of any of the reagents, after repairing the spectrophotometer (photocolorimeter), but at least once every three months.
9. MEASUREMENTS
9.1. Determination of orthophosphates
If necessary, the samples to be analyzed are filtered through a blue ribbon filter or a membrane filter.
9.0 cm 3 of the filtered sample (or, if the content of orthophosphates is more than 2.0 mg / dm 3 RO 4, its smaller volume diluted to 9.0 cm 3) is poured into a test tube with a screw cap, 0.5 cm 3 of mixed molybdenum -acid reagent and leave for at least 2 minutes. Next, 0.5 cm 3 of ascorbic acid solution is added, the test tube is closed with a screw cap and mixed.
After 15 - 20 minutes, the optical density (concentration, mg/dm 3 ) of the analyzed sample is measured relative to a blank sample at a wavelength of 880 - 890 nm.
As a blank sample, distilled water is used, drawn through the entire course of the analysis.
9.2. Determination of polyphosphates
5.0 cm 3 of the filtered sample or, if the content of polyphosphates is over 2.0 mg/dm 3 RO 4 , its smaller volume, diluted to 5.0 cm 3 , is poured into a test tube with a screw cap. Add 2.0 cm3 of 0.5 M sulfuric acid to the test tube, close it with a screw cap, place it in a mineralizer preheated to 120 ± 2 °C and keep it at this temperature for 30 minutes.
After cooling, 2.0 cm 3 1 M sodium hydroxide are added to the test tube, the solution is stirred. Then add 0.5 cm 3 of the mixed molybdic acid reagent and leave for at least 2 minutes. Add 0.5 cm 3 of ascorbic acid solution, close the tube and mix again.
9.3. Determination of total phosphorus
5.0 cm 3 of a thoroughly mixed analyzed sample (unfiltered!) or its smaller volume, brought to 5.0 cm 3, is poured into a test tube with a screw cap. Add 2.0 cm3 of 0.5 M sulfuric acid and 0.1 g of ammonium persulfate, close the test tube with a stopper, place it in a mineralizer preheated to 120 ± 2 °C and hold at this temperature for 30 minutes.
After cooling, 2.0 cm 3 1 M sodium hydroxide are added to the test tube, the solution is stirred. Then add 0.3 cm 3 of the mixed molybdic acid reagent and leave for at least 2 minutes. Add 0.3 cm 3 of ascorbic acid solution, close the tube and mix again.
Measurement of optical density is carried out in the same way as described in paragraph 9.1.
10. CALCULATION OF MEASUREMENT RESULTS
10.1. The mass concentration of orthophosphates (mg / dm 3 RO 4) in the analyzed sample is found according to the calibration curve, taking into account the preliminary dilution of the sample according to the formula:
X RO 4 - mass concentration of orthophosphates in the analyzed sample, mg/DM 3 RO 4;
From gr. - mass concentration of phosphates found according to the calibration curve, mg/dm 3 ;
V sampleRO 4 - the volume of the analyzed water sample taken for analysis, cm 3;
10.2. The mass concentration of the sum of polyphosphates (mg / dm 3 RO 4) in the analyzed sample is found by the formula:
X (RO 3) n - mass concentration of polyphosphates in the analyzed sample, mg/dm 3 RO 4;
V samples (RO 3) n - the volume of the analyzed water sample taken for mineralization with sulfuric acid according to clause 9.2, cm 3;
10 - the total volume of the solution in the test tube, cm3.
10.3. The mass concentration of total phosphorus (mg / dm 3 RO 4) in the analyzed sample is found according to the calibration curve, taking into account the preliminary dilution of the sample according to the formula:
Mass concentration of total phosphorus in the analyzed sample, mg/DM 3 RO 4 ;
From gr. - mass concentration of phosphates found according to the calibration curve, mg/dm 3 RO 4 ;
V samples Rtot. - the volume of the analyzed water sample taken for mineralization with ammonium persulfate according to paragraph 9.3 of the analysis, cm 3;
10 - the total volume of the solution in the test tube, cm3.
Notes : 1 . If sample previously dilute in dimensional flask, then this dilution also take into account at calculation concentration.
2 . At need representation result analysis in recalculation on the mass concentration R (mg / dm 3), her count on formula:
X P \u003d 0.326? X PO4.
11. PRESENTATION OF THE RESULTS OF MEASUREMENTS
The results of quantitative analysis in the analysis protocols are presented as:
X±D; mg / dm 3 (P = 0.95),
where D \u003d d? 0.01? C is the value of the accuracy indicator (see Table 2).
Measurement results are rounded up to:
12. ASSESSMENT OF ACCEPTABILITY OF THE RESULTS OF MEASUREMENTS
12.1. If necessary, the verification of the acceptability of the measurement results obtained under repeatability (convergence) conditions is carried out in accordance with the requirements of Section 5.2. GOST R ISO 5725-6-2002. The discrepancy between the measurement results should not exceed the repeatability limit (r). The r values are given in Table 3.
12.2. If necessary, verification of the acceptability of measurement results obtained under reproducibility conditions is carried out taking into account the requirements of section 5.3 of GOST R ISO 5725-6-2002. The discrepancy between the measurement results obtained by the two laboratories should not exceed the reproducibility limit (R). R values are given in Table 3.
Table 3
Defined indicator |
Measurement range, mg/dm 3 RO 4 |
Repeatability limit (for two measurement results), r, % |
Reproducibility limit (for two measurement results), R, % |
Drinking and natural waters |
|||
orthophosphates |
|||
polyphosphates |
|||
total phosphorus |
|||
Wastewater |
|||
orthophosphates |
|||
polyphosphates |
|||
phosphorus total. |
|||
13. QUALITY CONTROL OF THE RESULTS OF MEASUREMENTS DURING THE IMPLEMENTATION OF THE METHOD IN THE LABORATORY
13.1 Quality control of measurement results when implementing the methodology in the laboratory provides for:
Monitoring the stability of measurement results (based on monitoring the stability of the standard deviation of repeatability, intermediate precision and error);
Control by the executor of the procedure for performing measurements (based on the assessment of the error in the implementation of a single control procedure).
The frequency of control by the executor of the procedure for performing measurements and the algorithms of control procedures (using the method of additions, using samples for control, etc.), as well as the ongoing procedures for monitoring the stability of measurement results, are regulated in the internal documents of the laboratory.
13.2. Control of the procedure for performing measurements using the addition method
Samples for control are real water samples taken at traditional points for monitoring the composition of water. The volume of the sample taken for control should correspond to twice the volume required for the analysis according to the method. The selected volume is divided into two equal parts, the first of which is analyzed in accordance with the procedure and the result of the analysis of the initial working sample X 1 is obtained, and the additive of the analyzed component (C) is added to the second part and analyzed in accordance with the procedure, obtaining the result of the analysis of the working sample with addition X 2 . The results of the analysis of the original working sample X 1 and the working sample with the addition of X 2 are obtained, if possible, under the same conditions, i.e. they are received by one analyst using one set measuring utensils, the same reagents, etc.
The result of the control procedure K k is calculated by the formula:
K k \u003d | X 2 - X 1 - C |,
X 1 - the result of the analysis of the working sample;
X 2 the result of the analysis of the working sample with the addition of the analyzed component;
C - the amount of addition of the analyzed component;
The decision on a satisfactory error is made when the following condition is met:
K - error control standard, calculated by the formula.
,
D LH1 - the value of the characteristic of the error in measuring the concentration of the determined indicator in the working sample (mg / dm 3);
D LH2 - the value of the characteristic of the error in measuring the concentration of the determined indicator in the working sample with the additive (mg / dm 3).
The values of D LH1 and D LH2 in mg/dm 3 are set by the laboratory during the implementation of the methodology and are provided by monitoring the stability of the measurement results.
Note : It is permissible to calculate the error characteristic for the measurement results (X 1 and X 2) when implementing the methodology in the laboratory according to the formula: D L \u003d 0.84? D, where
D \u003d 0.01? d? X i;
d is an indicator of accuracy (see table 2).
With the accumulation of information in the process of monitoring the stability of the measurement results, the error characteristic is refined.
If the error control standard is exceeded, the experiment is repeated. When the specified standard K is repeatedly exceeded, the reasons leading to unsatisfactory control results are found out and eliminated.
ATTACHMENT 1
BLOCK SCHEME FOR THE DETERMINATION OF ORTHOPHOSPATES, POLYPHOSPHATES AND PHOSPHORUS BY THE GENERAL PHOTOMETRIC METHOD
Application area. one 1. Assigned characteristics of the measurement error and its components. 2 2. Measurement method. 2 3. Measuring instruments, auxiliary equipment, reagents and materials.. 3 4. Conditions safe conduct works. 4 5. Requirements for the qualification of the operator. 4 6. Conditions for performing measurements. 4 7. Collection and storage of water samples.. 4 8. Preparing to perform measurements. 4 9. Taking measurements. 6 10. Calculation of measurement results. 7 11. Registration of measurement results. 8 12. Assessment of the acceptability of measurement results. 8 13. Quality control of measurement results in the implementation of the methodology in the laboratory. nine Appendix 1. Block diagram of the determination of orthophosphates, polyphosphates and total phosphorus by photometric method.. 10 |
The issue of efficient treatment of polluted water from wastewater is one of the most pressing issues in the field of ecology and protection environment. It is no secret that pollution with substances of anthropogenic origin is perhaps the main reason for the deterioration of the quality of waste moisture.
Due to oil products, biogenic and organic elements, as well as surfactants, liquid masses in wastewater become simply - simply unsuitable for further discharge into water bodies and soil.
A thorough treatment of surface water is needed, during which all types of existing pollution will be effectively destroyed. Modern methods sewage moisture treatment should, in particular, eliminate ammonium nitrogen in wastewater, as well as other types of pollution.
Where do the chemicals in wastewater come from?
If we take for analysis the sewer liquid on the territory of a modern private house, we can find a huge number of the most heterogeneous elements, among which a large percentage of the elements will belong to a chemical nature.
When analyzing wastewater, you can detect total nitrogen in wastewater, hexavalent chromium in wastewater, total phosphorus in wastewater, copper in wastewater. Where do all these substances appear in the moisture, which is human waste?
The fact is that the industry has developed at a frantic pace over the past 10-20 years. In particular, dozens of various detergents were produced for general household use. There is also a sharp increase in demand for automatic washing machines.
Such factors were able to change the composition of household sewage water. The developed industry, which humanity is so proud of, has called into question the normal, good ecological situation on the planet.
What can we talk about if, when performing analyzes, ammonium nitrogen can be found in wastewater? In liquids, the volume of such contaminants can sometimes reach extremely high, dangerous levels. Particularly dangerous are nitrogen and phosphorus, the compounds of which trigger the process of eutrophication of water bodies, that is, they increase the biological vegetation of water bodies.
If the balance of nutrients exceeds the permissible norm, then the reservoir becomes a breeding ground for various undesirable biological vegetation - algae, undesirable varieties of plankton. Among other things, due to nitrogen and phosphorus, the life process of fish is disrupted.
About the most common chemical compounds
In wastewater, a wide range of different chemical compounds can be detected during the study. Some of them are extremely dangerous, others are moderately dangerous. However, all of them should not be present in the moisture that gets from the sewers of a private house into the soil and water bodies.
Zinc. One of the most commonly found items in stocks. Zinc is a trace element that is part of some enzymes. Zinc is also found in the human body, mainly in bones and hair. The maximum allowable concentration of this element in water bodies is 1 milligram per liter.
Numerous residents of private country houses are interested in forums on the Internet where zinc comes from in wastewater. The answer to this question is simple and prosaic: all chemical elements enter the drains from those substances that a person uses in everyday life. The substances are washing powders, detergents, shampoos, etc.
Nitrogen. This element is present in wastewater in two forms - as organic and inorganic compounds. Organic nitrogen in wastewater is formed as a result of the ingress of substances of a protein nature into the sewer - feces and food waste.
Almost all ammonium nitrogen is formed in wastewater during the hydrolysis of urine, the end product of nitrogen metabolism in humans. In addition, ammonium compounds are formed as a result of the ammonification of protein compounds.
The main parameter important for obtaining information about the volume of nitrogen-containing substances in sewage moisture is the indicator of total nitrogen. The environmental hazard of nitrogen compounds varies depending on the types of nitrogen-containing substances: nitrites are the most toxic group, nitrates are the safest, and ammonium occupies a middle position between them.
Phosphorus. This element may be present in stocks in various types- for example, in a dissolved state: it is phosphoric acid and its anions. Also, phosphorus is present in wastewater in the form of poly-, meta- and pyrophosphates.
The last three substances are actively used in the household: they can be found in almost any modern detergent. In addition, substances are used to prevent the formation of scale on the dishes. Other organophosphorus compounds may also be present in wastewater: nucleoproteins, phospholipids, as well as nucleic acids.
Iron. Substances containing iron are most often found in drains. It is, in general, one of the most common elements in nature. This is not to say that iron should not be present at all in sewer moisture.
Iron is an essential trace element, which in small quantities is simply necessary for plants and living organisms. However, iron is common in wastewater, as a rule, is present in quantities exceeding the allowable level.
In such cases, purification of water masses is necessary. The determination of sulfates in wastewater will also be considered mandatory. It is equally important to find organic sulfur compounds in wastewater, and bring the MPC to normal levels.
The total content of phosphorus present in the water of open natural reservoirs in the form of dissolved minerals, as well as in the composition of organic compounds, is called total. The primary factor determining the concentration of this element, like nitrogen, is the ion exchange that occurs between its mineral-organic forms and organisms inhabiting a particular water body.
Forms of phosphorus in natural waters
Table 1. Forms of phosphorus-containing compounds in water
Saturation indicators of total dissolved phosphorus for unpolluted natural water bodies are limited to 5-200 µg/dm 3 .
This element performs the function of a powerful biogenic agent. In natural water bodies, it is often the total content mineral-organic phosphorus becomes a factor constraining further growth in productivity. Ingestion of excess volumes of phosphorus-containing compounds into natural sources triggers the mechanisms of uncontrolled growth of plant biomass. Low-flowing and non-flowing objects are more susceptible to changes in the trophic status, which are accompanied by a complete restructuring of the entire structure of the reservoir: the concentration of bacteria and salts increases, putrefactive processes begin to predominate, as a result of which the water becomes cloudy.
Phosphorus in the reservoir comes from a number of sources, among which there are wastes from some industries, but most of its compounds enter the reservoirs as a result of agricultural and domestic human activities. This element is used in the composition of mineral fertilizers. Surface runoff from one irrigated hectare washes off about half a kilogram of phosphorus. Every day, up to 0.01-0.05 kg of phosphorus-containing substances per animal penetrates into water bodies from farms. Untreated and untreated domestic wastewater carries 0.003-0.006 kg per inhabitant daily.
One of the processes that influence eutrophication under such conditions is the flourishing of cyanobacteria. Many types of blue-green algae are toxic. They produce organic substances that are part of the group of nerve poisons. Secretions of cyanobacteria can cause dermatoses and cause disorders of the digestive tract. The ingestion of large masses of blue-green algae is dangerous for the development of paralysis.
Based on the GEMS / GEMS - global environmental monitoring system - the level of phosphorus is the most important criterion in determining the trophic state of open water bodies natural origin. Determination of saturation with total phosphorus (dissolved and suspended forms, organics and mineral compounds are taken into account) has become an obligatory item in the program for monitoring the composition of water bodies.
Phosphorus organic
Organophosphorus compounds synthesized by industrial methods are not considered in this category - this includes only substances that come as a result of the vital activity and decomposition of organisms inhabiting the reservoir, and as a result of metabolic processes occurring with sediments at its bottom. Organic phosphorus compounds are present in natural open water bodies in truly dissolved and colloidal states, as well as in suspension.
Phosphorus mineral
Mineral-phosphorus conglomerations enter water bodies due to chemical. weathering and dissolution of orthophosphate-containing rocks - apatites and phosphorites. They are also formed as a result of the decomposition of the remains of representatives of flora and fauna. In large quantities, phosphorus of mineral origin is introduced with wastewater containing fertilizers, synthetic hygiene products, chemical additives for boilers that prevent the formation of scale.
There are various ionic forms in which phosphorus penetrates from the surface of the watershed. These are both orthophosphate ions and polyphosphates. Pyrophosphates and metaphosphate ions make up a considerable part. Above pH 6.5, the dominant inorganic form (about ninety percent of the ions) is HPO 4 2- . In reservoirs with an acidic environment, the main compound is H 2 PO 4 - .
The content of phosphorus in open natural sources is negligible. In a liter, its value is usually limited to a few hundredths of a milligram, however, polluted water bodies can show a content of several milligrams. Underground sources are characterized by a concentration not exceeding 100 μg / dm 3 (with the exception of reservoirs located in places where predominantly phosphorus-containing rocks occur).
Change of seasons affects the level of phosphorus-containing compounds. Moreover, the fluctuations are quite significant. Saturation spikes are affected by natural changes in the rate of biochemical oxidation and photosynthesis. The spring-summer period is characterized by minimum levels of content, but in the autumn-winter months, the maximum content of phosphorus is observed. In the seas, there is a spring and autumn decrease in the level of phosphorus, and the highest rates are recorded in winter and summer.
Salts of phosphoric acid show their toxicity only at high concentrations. Often, the chemical activity of phosphates is due to the presence of fluorine impurities in the reservoir.
The State Committee for Ecology of the Russian Federation, when drawing up a methodology for assessing the environmental situation, recommended an indicator of 50 μg / dm 3 as a standard - this is the content of phosphates that is considered acceptable.
Suspensions and solutions of inorganic phosphates are determined without preliminary manipulations - colorimetric samples.
Polyphosphates
The toxicity of these phosphorus derivatives is negligible. Polyphosphates are the product of the formation of compounds between polyphosphates and calcium, as well as other ions that play a biologically important role.
Me n (PO 3) n , Me n+2 PnO 3n+1 , Me n H 2 PnO 3n+1
These substances are used in food production as catalysts and in boiler water treatment as corrosion inhibitors. With their help, fibers are degreased and water softens. Polyphosphates are essential components of soaps and laundry detergents.
Residual volume of polyphosphates allowed for drinking water bodies - 3.5 mg/dm 3 (organoleptic indicator of harmfulness limit).
Dear Sirs, if you have a need to correct the concentration of phosphorus-containing compounds in order to bring the water quality up to certain standards, make a request to the company's specialists Waterman. We will develop for you the optimal technological scheme of water purification.
Wastewater is a complex heterogeneous system containing pollution of various nature. Substances are presented in soluble and insoluble, organic and inorganic form. The concentration of compounds varies, in particular, organic pollution in domestic wastewater is presented in the form of proteins, carbohydrates, fats and biological products. In addition, the effluents contain rather large impurities - waste of vegetable origin, such as paper, rags, hair and synthetic substances. Inorganic compounds are represented by phosphate ions, the composition may include nitrogen, calcium, magnesium, potassium, sulfur and other compounds.
The composition of household waste always includes biological substances in the form of mold fungi, worm eggs, bacteria, viruses. It is because of the presence of pollutants that wastewater is considered dangerous for humans, plants and animals in epidemiological terms.
To determine the composition and amount of suspended particles in the discharge water, it is necessary to conduct many analyzes of the chemical and sanitary-bacteriological type. The results will show the level of concentration of contaminants in the water, which means the most optimal treatment option. But a complete analysis is not always possible, so it is easier to use a simplified version that gives an incomplete characterization of water, but provides information about transparency, the presence of suspended particles, the concentration of dissolved oxygen and the need for it.
The analysis is carried out according to the following indicators:
- Temperature . The indicator indicates the rate of sediment formation from suspensions and the intensity of the biological species processes that affect the efficiency and quality of cleaning.
- Colour, coloration. Domestic wastewater rarely has a pronounced color, but if there is such a factor, the quality of the wastewater is very poor and needs to be strengthened treatment facilities or a complete replacement of the cleaning method.
- Smells. As a rule, a high concentration of organic decomposition products, the presence of phosphates in the wastewater and nitrogen, potassium, and sulfur included in the composition give the streams a sharp unpleasant odor.
- Transparency. This is an indicator of the level of contaminants contained, determined by the font method. For domestic water, the standard is 1-5 cm, for flows that have undergone purification methods with biological compounds - from 15 cm.
- The pH level is used to measure the reaction of the environment. Permissible indicators 6.5 - 8.5.
- Sediment. It is the dense sediment, determined by the sample filtrate, that is measured. According to SNiP standards, no more than 10g/l is allowed.
- suspended solids make up no more than 100-500 cg / l in urban waters with an ash content of up to 35%.
Phosphorus and nitrogen, as well as all their forms, are studied separately. 4 forms of nitrogen are taken: total, ammonium, nitrite and nitrate. In wastewater, the general and ammonium types are more common, nitrite and nitrate only if treatment methods were used by means of aerotanks and biofiltrates. Establishing the concentration of nitrogen and its forms is an important component of the analysis, since nitrogen is necessary for the nutrition of bacteria, like phosphorus.
As a rule, nitrogen in domestic wastewater is contained in full, but there is not enough phosphate, therefore, if there is a shortage, phosphates are often replaced by lime (ammonium chloride).
- sulfates and chlorides are not subject to changes during treatment, the removal of suspended solids is possible only with the complete processing of wastewater, however, the content of substances in low concentrations does not affect biochemical processes, therefore, the permissible parameters remain within 100 mg/l.
- Toxic elements- these are also suspended substances, however, even a small concentration of compounds has negative influence on the life and activities of organisms. That is why suspended solids of a toxic type are classified as especially polluting and are separated into a separate group. These include: sulfides, mercury, cadmium, lead and many other compounds.
- Synthetic surfactant suspended solids is one of the most serious threats. The content of elements in wastewater negatively affects the state of water bodies, and also reduces the functionality of treatment facilities.
Only 4 groups of surfactants differ:
- Anionic - compounds account for ¾ of the world production of synthetic surfactants;
- Non-onogenic - occupy the second place in terms of concentration in urban wastewater;
- Cationic- slow down the cleaning processes occurring in the sedimentation tanks;
- Amphoteric - rare, but significantly reduce the efficiency of removing waste from the water.
Dissolved oxygen is contained in drain waters no more than 1 mg / l, which is extremely small for the normal operation of microorganisms that are responsible for removing suspended particles from wastewater. Maintaining the vital activity of bacteria requires from 2 mg / l, therefore, it is important to control the content of dissolved oxygen in domestic waste water, especially those that are discharged into artificial or natural reservoirs - failure to comply with acceptable standards for the content of dissolved oxygen will lead to the appearance of polluting particles in lakes and disruption of natural natural balance. And this already means the extinction of natural resources.
As for the biological compounds that make up the drain waters, the purification process copes with them by 90% or more. This is especially true of helminth eggs, which are found in streams in a wide variety. The concentration of eggs reaches up to 92% of the total composition of pollutants, so the removal of elements is one of the most important tasks.
Treatment options for domestic and industrial waste water
The most practical and popular is the method in which removal is carried out biologically. Functionally, the process is the processing by active biological components of polluting particles that have fallen into domestic wastewater. There are two options for removal:
- Anaerobic - the process of destruction of substances without access to air / oxygen;
- Aerobic - the destruction and removal of suspended particles by beneficial microorganisms with the supply of oxygen.
In addition, artificial conditions are created for better processing of organics, but sometimes bacterial colonies are enough for the treatment of domestic waste streams to take place in natural conditions, and it is only important to monitor the flow of a sufficient amount of organics.
Artificially created conditions are called filter fields. These are special areas with sandy or loamy soil, prepared for natural biological purification of contaminants in drain waters by filtering through the soil layers. In this way, the permissible levels of the content of substances are achieved. The process proceeds with the help of aerobic and anaerobic bacteria contained in the soil, so the removal of polluting particles is considered more complete. However, the method cannot always eliminate phosphates and nitrogen in the treated waters, and is also considered inconvenient due to large areas, seasonal use and bad smell.
The use of septic tanks and aeration biological treatment plants can also cope with wastewater treatment. The advantages of artificial sewage treatment plants are in the possibility of intensifying cleaning processes, retrofitting equipment such as biofilters, as well as the ability to use structures throughout the year. Of great importance is the ability to clean without an unpleasant odor. While maintaining a favorable climate and receiving a sufficient amount of organic matter, the cleaning process takes place continuously, and the most serious polluting compounds, the concentration of which is exceeded, are removed. But it is important to remember that the total composition of incoming effluents should not contain many elements, such as:
- Chemical acids;
- Gasolines and solvents;
- Biologically active substances;
- antibiotics;
- Compounds of washing powders, detergents;
- Abrasives.
With all the possibilities of removal, cleaning in domestic septic tanks cannot cope with the compounds of phosphates, nitrates, and nitrogen also does not neutralize, however, a significantly reduced concentration allows the accumulation of purified streams in reservoirs, from where to take water for irrigation or technical needs.
Suspended substances that are part of the drain streams are removed by a biological treatment method, that is, by cultivating microorganisms in the waters that destroy the compounds of polluting particles. Organics can be of both plant and animal origin, with carbon being the main component of plant debris, and nitrogen being the main component of animal debris. That is why the total composition of beneficial bacteria for wastewater treatment must contain all types of microorganisms in order to successfully cope with the removal of contaminants.
In order to remove aggressive chemical compounds, phosphates, toxic substances that are part of industrial effluents in wastewater, centralized treatment systems are used, which show the use of strong reagents and chemicals. And in order to cope with pollution in domestic waters, where water is taken from for irrigation, car washing and other household needs, high-quality septic tanks are enough.
Phosphorus total
The sum of mineral and organic phosphorus. Just as for nitrogen, the exchange of phosphorus between its mineral and organic forms, on the one hand, and living organisms, on the other, is the main factor determining its concentration. The concentration of total dissolved phosphorus (mineral and organic) in unpolluted natural waters varies from 5 to 200 µg/dm 3 .
Forms of phosphorus in natural waters
Chemical forms of phosphorus | General | Filterable (dissolved) | Particles |
General | total dissolved phosphorus | Total phosphorus in particles | |
Orthophosphates | Total dissolved and suspended phosphorus | Dissolved orthophosphates | Orthophosphates in particles |
Acid hydrolysable phosphates | Total Dissolved and Suspended Acid-Hydrolysable Phosphates | Dissolved acid hydrolysable phosphates | Acid hydrolysable phosphates in particles |
Organic phosphorus | Total dissolved and suspended organic phosphorus | Dissolved organic phosphorus | Organic phosphorus in particles |
Phosphorus is the most important biogenic element, most often limiting the development of the productivity of water bodies. Therefore, the supply of excess phosphorus compounds from the watershed (in the form of mineral fertilizers with surface runoff from fields (0.4-0.6 kg of phosphorus is taken out per hectare of irrigated land), with runoff from farms (0.01-0.05 kg/day. per animal), with undertreated or untreated household sewage(0.003-0.006 kg / day per inhabitant), as well as with some industrial waste, leads to a sharp uncontrolled increase in the plant biomass of a water body (this is especially typical for stagnant and slow-flowing water bodies). There is a so-called change in the trophic status of the reservoir, accompanied by a restructuring of the entire aquatic community and leading to the predominance of putrefactive processes (and, accordingly, an increase in turbidity, salinity, and bacterial concentration). One likely aspect of the eutrophication process is the growth of blue-green algae (cyanobacteria), many of which are toxic. The substances secreted by these organisms belong to the group of phosphorus- and sulfur-containing organic compounds (nerve poisons). The action of blue-green algae toxins can manifest itself in the occurrence of dermatoses, gastrointestinal diseases; in especially severe cases - when a large mass of algae enters the body, paralysis may develop. As required global system monitoring of the state of the environment (GEMS/GEMS) in the programs of obligatory observations of the composition of natural waters, the determination of the content of total phosphorus (dissolved and suspended, in the form of organic and mineral compounds) is included. Phosphorus is the most important indicator of the trophic status of natural water bodies.
Phosphorus organic
This section does not cover commercially synthesized organophosphorus compounds. Natural compounds of organic phosphorus enter natural waters as a result of vital processes and post-mortem decay of aquatic organisms, exchange with bottom sediments. Organic phosphorus compounds are present in surface waters in dissolved, suspended and colloidal states.
Phosphorus mineral
Mineral phosphorus compounds enter natural waters as a result of weathering and dissolution of rocks containing orthophosphates (apatites and phosphorites) and from the surface of the catchment area in the form of ortho-, meta-, pyro- and polyphosphate ions (fertilizers, synthetic detergents, additives that prevent scaling in boilers, etc.), and are also formed during the biological processing of the remains of animal and plant organisms. The excess content of phosphates in water, especially in groundwater, may be a reflection of the presence of fertilizer impurities, household wastewater components, and decomposing biomass in the water body. The main form of inorganic phosphorus at pH values of the reservoir above 6.5 is the HPO 4 2- ion (about 90%). In acidic waters, inorganic phosphorus is present mainly in the form of H 2 PO 4 - . The concentration of phosphates in natural waters is usually very small - hundredths, rarely tenths of milligrams of phosphorus per liter, in polluted waters it can reach several milligrams per 1 dm3. Groundwater usually contains no more than 100 µg/dm 3 phosphates; the exception is waters in areas where phosphorus-bearing rocks occur. The content of phosphorus compounds is subject to significant seasonal fluctuations, since it depends on the ratio of the intensity of the processes of photosynthesis and biochemical oxidation organic matter. The minimum concentrations of phosphates in surface waters are usually observed in spring and summer, the maximum - in autumn and winter, in sea waters - in spring and autumn, summer and winter, respectively. The general toxic effect of salts of phosphoric acid is possible only at very high doses and is most often due to impurities of fluorine. In the methodology for assessing the environmental situation, adopted by the State Committee for Ecology of the Russian Federation, the recommended standard for the content of soluble phosphates in water is 50 μg / dm 3. Without prior sample preparation, inorganic dissolved and suspended phosphates are determined colorimetrically.
Polyphosphates
Me n (PO 3) n , Me n+2 P n O 3n+1 , Me n H 2 P n O 3n+1
They are used for water softening, fiber degreasing, as a component of washing powders and soaps, corrosion inhibitor, catalyst, in Food Industry. Low toxicity. The toxicity is attributed to the ability of polyphosphates to form complexes with biologically important ions, especially calcium. The established permissible residual amount of polyphosphates in drinking water is 3.5 mg / dm 3 (the limiting indicator of harmfulness is organoleptic).
Sulfur compounds
Hydrogen sulfide and sulfides.
Usually, hydrogen sulfide is not contained in the waters or is present in small quantities in the bottom layers, mainly in winter, when aeration and wind mixing of water masses is difficult. Sometimes hydrogen sulfide appears in noticeable amounts in the bottom layers of water bodies and in summer during periods of intense biochemical oxidation of organic substances. The presence of hydrogen sulfide in the waters is an indicator of severe pollution of the reservoir with organic substances. Hydrogen sulfide in natural waters is in the form of undissociated H 2 S molecules, hydrosulfide ions HS - and very rarely - sulfide ions S 2-. The ratio between the concentrations of these forms is determined by the pH values of water: at pH< 10 содержанием ионов сульфида можно пренебречь, при рН=7 содержание H 2 S и HS - примерно одинаково, при рН=4 сероводород почти полностью (99,8%) находится в виде H 2 S. Главным источником сероводорода и сульфидов в поверхностных водах являются восстановительные процессы, протекающие при бактериальном разложении и биохимическом окислении органических веществ естественного происхождения и веществ, поступающих в водоем со сточными водами (хозяйственно-бытовыми, предприятий пищевой, металлургической, химической промышленности, производства сульфатной целлюлозы (0,01-0,014 мг/дм 3) и др.). Особенно интенсивно процессы восстановления происходят в подземных водах и придонных слоях водоемов в условиях слабого перемешивания и дефицита кислорода. Значительные количества сероводорода и сульфидов могут поступать со сточными водами нефтеперерабатывающих заводов, с городскими сточными водами, водами производств минеральных удобрений. Концентрация сероводорода в водах быстро уменьшается за счет окисления кислородом, растворенным в воде, и микробактериологических процессов (тионовыми, бесцветными и окрашенными серными бактериями). В процессе окисления сероводорода образуются сера и сульфаты. Интенсивность процессов окисления сероводорода может достигать 0,5 грамм сероводорода на литр в сутки. Причиной ограничения концентраций в воде является высокая токсичность сероводорода, а также неприятный запах, который резко ухудшает органолептические свойства воды, делая ее непригодной для питьевого водоснабжения и других технических и хозяйственных целей. Появление сероводорода в придонных слоях служит признаком острого дефицита кислорода и развития заморных явлений , . Для водоемов санитарно-бытового и рыбохозяйственного пользования наличие сероводорода и сульфидов недопустимо (ПДК - полное отсутствие) .
sulfates
They are present in almost all surface waters and are one of the most important anions. The main source of sulfates in surface waters are the processes of chemical weathering and dissolution of sulfur-containing minerals, mainly gypsum, as well as the oxidation of sulfides and sulfur:
2FeS 2 + 7O 2 + 2H 2 O \u003d 2FeSO 4 + 2H 2 SO 4;
2S + 3O 2 + 2H 2 O \u003d 2H 2 SO 4.
Significant amounts of sulfates enter water bodies in the process of dying off organisms and the oxidation of terrestrial and aquatic substances of plant and animal origin and with underground runoff. Large amounts of sulfates are found in mine waters and in industrial effluents from industries that use sulfuric acid, such as the oxidation of pyrite. Sulfates are also carried out with wastewater from public utilities and agricultural production. The ionic form SO 4 2- is typical only for low-mineralized waters. With an increase in mineralization, sulfate ions tend to form stable associated neutral pairs such as CaSO 4 , MgSO 4 . The content of sulfate ions in solution is limited by the relatively low solubility of calcium sulfate (solubility product of calcium sulfate L=6.1·10 -5). At low calcium concentrations, as well as in the presence of foreign salts, the concentration of sulfates can increase significantly. Sulfates are actively involved in the complex cycle of sulfur. In the absence of oxygen, under the action of sulfate-reducing bacteria, they are reduced to hydrogen sulfide and sulfides, which, when they appear in natural water oxygen is oxidized again to sulfates. Plants and other autotrophic organisms extract sulfates dissolved in water to build proteins. After the death of living cells, heterotrophic bacteria release protein sulfur in the form of hydrogen sulfide, which is easily oxidized to sulfates in the presence of oxygen. The concentration of sulfates in natural water lies within a wide range. In river waters and in the waters of fresh lakes, the content of sulfates often ranges from 5-10 to 60 mg / dm 3, in rainwater - from 1 to 10 mg / dm 3. In groundwater, the content of sulfates often reaches significantly higher values. Sulphate concentrations in surface waters are subject to marked seasonal fluctuations and usually correlate with changes in the total salinity of the water. The most important factor, which determines the regime of sulfates, are the changing ratios between surface and underground runoff. A significant influence is exerted by redox processes, the biological situation in the water body and economic activity person. Elevated sulfate levels worsen the organoleptic properties of water and have a physiological effect on the human body. Since sulfate has laxative properties, its maximum allowable concentration is strictly regulated by regulations. Very stringent requirements for the content of sulfates are imposed on water supplying steam power plants, since in the presence of calcium sulfates form a strong scale. The taste threshold of magnesium sulfate lies in the range from 400 to 600 mg/dm 3 , for calcium sulfate - from 250 to 800 mg/dm 3 . The presence of sulfate in industrial and drinking water can be both beneficial and harmful. MPC in sulfates is 500 mg/dm 3 , MPC in BP is 100 mg/dm 3 . Sulfate in drinking water has not been observed to affect corrosion processes, but if lead pipes are used, sulfate concentrations above 200 mg/dm 3 can lead to lead leaching into the water.
carbon disulfide
Transparent volatile liquid with a pungent odor. It can enter large quantities into open water bodies with wastewater from viscose silk factories, artificial leather factories and a number of other industries. When the content of carbon disulfide in the amount of 30-40 mg/dm 3 there is a depressing effect on the development of saprophytic microflora. The maximum concentration that does not have a toxic effect on fish is 100 mg / dm 3. Carbon disulfide is a polytropic poison that causes acute and chronic intoxication. Affects central and peripheral nervous system, causes disruption of cardio-vascular system. It has a damaging effect on the organs of the gastrointestinal tract. Violates the exchange of vitamin B6 and nicotinic acid. MPC v - 1.0 mg / dm 3 (limiting indicator of harmfulness - organoleptic), MPC vr - 1.0 mg / dm 3 (limiting indicator of harmfulness - toxicological), .
- The Curonian Bay of the Baltic Sea: description, water temperature and the underwater world
- Ecological groups of birds by type of food Ecological birds examples
- A fairy tale in reality - the animal world of the Red Sea: a sketch about underwater inhabitants Dangerous fish of the Red Sea hurghada
- Parnassius (Parnassius)