Indicator of turbidity of water. Turbidity of water

4. The limitation of the validity period has been removed according to protocol N 4-93 of the Interstate Council for Standardization, Metrology and Certification (IUS 4-94)

5. EDITION (September 2003) with Amendment No. 1, approved in February 1985 (IUS 5-85)


This International Standard applies to drinking water and specifies organoleptic methods for the determination of odor, taste and taste and photometric methods for the determination of color and turbidity.

1. SAMPLING

1. SAMPLING

1.1. Sampling - in accordance with GOST 24481 *.

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* In the territory Russian Federation GOST R 51593-2000 is in force.

1.2. The volume of the water sample should not be less than 500 ml.

1.3. Water samples for the determination of odor, taste, taste and color are not preserved. The determination is carried out no later than 2 hours after sampling.

2. ORGANOLEPTIC METHODS FOR DETERMINING ODOR

2.1. Organoleptic methods determine the nature and intensity of the smell.

2.2. Equipment, materials

The following equipment is used for testing:

flat-bottomed flasks with ground-in stoppers in accordance with GOST 1770, with a capacity of 250-350 cm3;

watch glass;

water bath.

2.3. Testing

2.3.1. The nature of the smell of water is determined by the sensation of the perceived smell (earthy, chlorine, oil products, etc.).

2.3.2. Determination of odor at 20 ° C

In a flask with a ground stopper with a capacity of 250-350 ml, measure 100 ml of the test water at a temperature of 20 ° C. The flask is closed with a stopper, the contents of the flask are mixed several times rotational movements, after which the flask is opened and the nature and intensity of the odor is determined.

2.3.3. Determination of odor at 60 ° C

Measure 100 ml of the test water into the flask. The neck of the flask is closed with a watch glass and heated in a water bath to 50-60 ° C.

The contents of the flask are mixed several times with rotary movements.

By moving the glass to the side, they quickly determine the nature and intensity of the smell.

2.3.4. The intensity of the odor of water is determined at 20 and 60 ° C and is assessed by five-point system according to the requirements of Table 1.

Table 1

3. ORGANOLEPTIC METHOD FOR DETERMINING TASTE

3.1. The character and intensity of taste and aftertaste are determined by the organoleptic method.

There are four main types of taste: salty, sour, sweet, bitter.

All other types of taste sensations are called aftertastes.

3.2. Testing

3.2.1. The character of the taste or taste is determined by the perception of the perceived taste or taste (salty, sour, alkaline, metallic, etc.).

3.2.2. The test water is taken into the mouth in small portions, without swallowing, it is delayed for 3-5 s.

3.2.3. The intensity of taste and taste is determined at 20 ° C and evaluated on a five-point system in accordance with the requirements of Table 2.

table 2

4. PHOTOMETRIC METHOD FOR DETERMINING COLOR

The color of water is determined photometrically - by comparing samples of the test liquid with solutions that imitate the color of natural water.

4.1. Equipment, materials, reagents

The following equipment, materials, reagents are used for testing:

photoelectric colorimeter (FEK) with a blue light filter (= 413 nm);

cuvettes with a thickness of the light-absorbing layer of 5-10 cm;

volumetric flasks in accordance with GOST 1770, with a capacity of 1000 cm3;

measuring pipettes according to GOST 29227, with a capacity of 1, 5, 10 cm with divisions of 0.1 cm;

Nessler cylinders 100 cm;

potassium dichromate in accordance with GOST 4220;

sulphate cobalt in accordance with GOST 4462;

sulfuric acid in accordance with GOST 4204, with a density of 1.84 g / cm3;

distilled water in accordance with GOST 6709;

membrane filters N 4.

All reagents used in the analysis must be of the "analytical grade" qualification.

(Modified edition, Amendment N 1).

4.2. Test preparation

4.2.1. Preparation of the stock standard solution (solution No. 1)

0.0875 g of potassium dichromate (KCrO), 2.0 g of cobalt sulfate (CoSO 7HO) and 1 cm3 of sulfuric acid (density 1.84 g / cm3) are dissolved in distilled water and the volume of the solution is adjusted to 1 dm3. The solution corresponds to a color of 500 °.

4.2.2. Preparation of a dilute sulfuric acid solution (solution N 2)

1 cm3 of concentrated sulfuric acid with a density of 1.84 g / cm3 is brought to 1 dm3 with distilled water.

4.2.3. Preparation of the chromaticity scale

To prepare the color scale, a set of Nessler cylinders with a capacity of 100 ml is used.

In each cylinder, a solution of N 1 and a solution of N 2 are mixed in the ratio indicated on the color scale (Table 3).

Chromaticity scale

Table 3

The solution in each cylinder corresponds to a certain degree of color. The chromaticity scale is stored in a dark place. It is replaced every 2-3 months.

4.2.4. Building a calibration graph

The calibration graph is plotted on the chromaticity scale. The obtained values ​​of optical densities and the corresponding degrees of chromaticity are plotted on the graph.

4.2.5. Testing

In the Nessler cylinder, measure 100 cm of the test water filtered through a membrane filter and compare it with the color scale, viewing from above on a white background. If the test water sample has a color of more than 70 °, the sample should be diluted with distilled water in a certain ratio until the color of the test water is comparable to the color of the color scale.

The result obtained is multiplied by the number corresponding to the dilution.

When determining the chromaticity using an electrophotocolorimeter, cuvettes with a thickness of a light-absorbing layer of 5-10 cm are used. Distilled water serves as a control liquid, from which suspended substances are removed by filtration through membrane filters No. 4.

The optical density of the filtrate of the investigated water sample is measured in the blue part of the spectrum with a light filter at = 413 nm.

Chromaticity is determined by a calibration graph and expressed in degrees of chromaticity.

5. PHOTOMETRIC METHOD FOR DETERMINING TURBOIDITY

5.1. Determination of turbidity is carried out no later than 24 hours after sampling.

The sample can be preserved by adding 2-4 ml of chloroform per 1 dm 3 of water.

The turbidity of water is determined photometrically - by comparing the samples of the investigated water with standard suspensions.

The measurement results are expressed in mg / dm3 (when using the main standard suspension of kaolin) or in EM / dm (units of turbidity per dm3) (when using the main standard suspension of formazin). The transition from mg / DM to EM / DM is carried out proceeding from the ratio: 1.5 mg / DM of kaolin corresponds to 2.6 EM / DM of formazin or 1 EM / DM corresponds to 0.58 mg / DM.

5.2. The following equipment, materials, reagents are used for testing:

photoelectric colorimeter of any brand with a green light filter = 530 nm;

cuvettes with a thickness of the light-absorbing layer of 50 and 100 mm;

laboratory scales in accordance with GOST 24104 *, accuracy class 1, 2;
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* From July 1, 2002, GOST 24104-2001 was introduced **.

** The document is not valid on the territory of the Russian Federation. GOST R 53228-2008 is in effect, hereinafter in the text. - Note from the manufacturer of the database.

drying cabinet;

centrifuge;

porcelain crucibles in accordance with GOST 9147;

a device for filtration through membrane filters with a water-jet pump;

measuring pipettes according to GOST 29227, with a capacity of 25, 100 cm3;

measuring pipettes according to GOST 29227, with a capacity of 1, 2, 5, 10 cm with divisions of 0.1 cm;

graduated cylinders in accordance with GOST 1770, with a capacity of 500 and 1000 cm3;

enriched kaolin for the perfumery industry in accordance with GOST 21285 or for the cable industry in accordance with GOST 21288;

potassium pyrophosphate KRO · 3HO or sodium pyrophosphate NaPO · 3HO;

hydrazine sulfate (NH) · HSO in accordance with GOST 5841;

hexamethylenetetramine for single crystals (CH) N;

mercury chloride;

formalin according to GOST 1625;

chloroform in accordance with GOST 20015;

distilled water in accordance with GOST 6709 and bidistilled;

membrane filter with a pore diameter of 0.5-0.8 µm, which must be prepared for analysis in accordance with the manufacturer's instructions.

Membrane filters (nitrocellulose) are checked for cracks, holes, etc., placed one at a time on the surface of distilled water heated to 80 ° C in a glass (in an evaporation cup, enamel pan), slowly brought to a boil over low heat, after which the water is replaced and boiled for 10 minutes. The change of water and subsequent boiling are repeated three to five times until the residual solvents are completely removed from the filters.

Filtration membranes "Vladipor" of the FMA-MA type, visually checked for cracks, holes, bubbles, in order to avoid twisting of the membranes, are boiled once, observing the following rules:

in a small volume of distilled water heated to 80-90 ° C in a vessel, at the bottom of which a milk watchdog or a stainless steel mesh is placed (to limit violent boiling), place membranes and boil over low heat for 15 minutes.

The membranes are then ready for use.

5.3. Test preparation

Standard suspensions can be made from kaolin or formazin.

5.1-5.3. (Modified edition, Amendment N 1).

5.3.1. Preparation of the main standard slurry from kaolin

25-30 g of kaolin is shaken well with 3-4 dm3 of distilled water and left to stand for 24 hours. After 24 hours, the unclarified part of the liquid is siphoned off. Water is again added to the remaining part, shaken vigorously, again left alone for 24 hours, and the middle unclarified part is again selected. This operation is repeated three times, each time adding a suspension not clarified during the day to the previously collected one. The accumulated suspension is shaken well and after three days the liquid above the sediment is drained, as containing too small particles.

To the resulting precipitate add 100 cm3 of distilled water, shake and get the main standard suspension.

The concentration of the main suspension is determined by weight method(from at least two parallel samples): 5 cm of the suspension is placed in a crucible brought to constant weight, dried at a temperature of 105 ° C to constant weight, weighed and calculate the kaolin content per 1 dm 3 of the suspension.

Then the main standard suspension is stabilized with potassium or sodium pyrophosphate (200 mg per 1 l) and preserved with a saturated solution of mercury chloride (1 cm per 1 dm), formalin (10 cm per 1 dm) or chloroform (1 cm per 1 dm).

The main standard suspension is stored for 6 months. This basic standard slurry should contain about 4 g / L of kaolin.

5.3.2. Preparation of working standard suspensions from kaolin

To prepare working standard suspensions of turbidity, the main standard suspension is agitated and a suspension is prepared from it containing 100 mg / l of kaolin. Working suspensions with a concentration of 0.5 are prepared from the intermediate suspension; 1.0; 1.5; 2.0; 3.0; 4.0; 5.0 mg / dm. The intermediate suspension and all working suspensions are prepared in bidistilled water and stored for no more than a day.

5.3.3. Preparation of the main standard suspension from formazin

5.3.1-5.3.3. (Modified edition, Amendment N 1).

5.3.3.1. Preparation of the main standard suspension of formazin I containing 0.4 IU in 1 cm of solution

Solution A. Dissolve 0.5 g of hydrazine sulfate (NH) · HSO in distilled water and dilute to 50 ml.

Solution B. Dilute 2.5 g of hexamethylenetetramine (CH) N in a 500 ml volumetric flask in 25 ml of distilled water.

Add 25 ml of solution A to solution B and incubate for (24 ± 2) h at a temperature of (25 ± 5) ° С. Then add distilled water to the mark. The main standard suspension of formazin is stored for 2 months and does not require preservation and stabilization.

5.3.3.2. Preparation of a standard suspension of formazin II containing 0.04 IU in 1 cm of solution

50 ml of a thoroughly mixed base standard suspension of formazin I is diluted with distilled water to a volume of 500 ml. A standard suspension of formazin II is stored for two weeks.

5.3.3.1, 5.3.3.2. (Introduced additionally, Rev. N 1).

5.3.4. Preparation of working standard formazin suspensions

2.5; 5.0; 10.0; 20.0 cm3 of a premixed standard suspension of formazin II is brought to a volume of 100 cm3 with bidistilled water and working standard suspensions of concentration 1 are obtained; 2; 4; 8 EM / dm.

5.3.5. Building a calibration graph

A calibration graph is plotted using standard working suspensions. The obtained values ​​of optical densities and the corresponding concentrations of standard suspensions (mg / dm; EM / dm) are plotted on the graph.

5.4. Testing

Before testing, in order to avoid errors, the photocolorimeters are calibrated against liquid standard suspensions of turbidity or a set of solid standard suspensions of turbidity with known optical density.

A well-shaken test sample is introduced into a cuvette with a 100 mm light-absorbing layer and the optical density is measured in the green part of the spectrum (= 530 nm). If the color of the measured water is below 10 ° according to the Cr-Co scale, then double-distilled water serves as the control liquid. If the color of the measured sample is higher than 10 ° Сr-С scale, then the test water serves as a control liquid, from which suspended substances are removed by centrifugation (centrifuged for 5 min at 3000 min) or by filtration through a membrane filter with a pore diameter of 0.5-0.8 μm.

The turbidity content in mg / dm3 or EM / dm3 is determined according to the corresponding calibration curve.

The final result of the determination is expressed in mg / dm3 for kaolin.

5.3.4, 5.3.5, 5.4. (Modified edition, Amendment N 1).



Electronic text of the document
prepared by JSC "Kodeks" and verified by:

official publication

Water quality control:
Sat. GOSTs. - M .: FGUP

"STANDARDINFORM", 2010

Chromaticity - natural property water due to the presence of humic substances in it, which are washed out into the water from the soil. Humic substances are formed in the soil as a result of microbiological destruction of foreign organic compounds and the synthesis by soil microorganisms of a new organic matter inherent in the soil, which is called humus. Humus is brown in color, and therefore humic substances give the water a color from yellow to brown. The amount of these substances is influenced by geological conditions, aquifers, the nature of the soil, the presence of bogs and peatlands in river basins, etc. A small amount of humic substances is formed directly in surface water bodies due to microbiological destruction of aquatic plants (algae). The more humic substances in the water, the higher the color of the water and the more intense its color.

To measure the level of chromaticity, a chromium-cobalt scale has been developed that imitates the chromaticity of natural water. This scale represents solutions of potassium chromate, cobalt sulfate, and sulfuric acid in water. The higher the concentration of these substances, the more intense the yellow-brown color of the solution and the greater the color. To assess the color of water, you can use the platinum-cobalt scale. The color of water is measured in degrees by comparing its intensity with the coloration of solutions on a chrome-cobalt or platinum-cobalt scale. Previously, this comparison was carried out visually, but now spectrophotometers and photocolorimeters are used.

Almost colorless can be considered only such water, the color of which is not perceived by the eye and does not exceed 20 degrees. Only in this case, its use is not limited and the search for other opportunities for quenching thirst will not be carried out. If the majority of consumers say that the water is yellowish, then its color on a simulated scale is greater than 20 degrees. That is why the state standard for drinking tap water states that its color should not exceed 20 degrees.

In addition to color, you should also remember about the color of the water. It is associated with water pollution with substances of organic and inorganic origin, in particular, dyes that can enter water bodies with wastewater from light industry enterprises, some inorganic compounds iron, manganese, copper, both natural and technogenic origin. Thus, iron and manganese can color water in colors from red to black, copper - from pale blue to blue-green, that is, water polluted by industrial effluents can have an unnatural color.

The color is determined visually or photometrically after removing suspended solids by filtration or centrifugation. Visually study the color, shade, intensity of water color. To do this, water is poured into a flat-bottomed cylinder. A sheet of white paper is placed at a distance of 4 cm from the bottom. The leaf is examined through a column of water in the cylinder and its color is assessed. The water is drained from the cylinder until the color is perceived as white, inherent in the entire sheet of paper. The height of the column is measured at which the color disappears. The color of water should not be determined in a column 20 cm high. Sometimes, if the color is very intense, there is a need to dilute the test water with distilled water. The intensity and nature of the color of water can be determined by measuring its optical density with a spectrophotometer or photocolorimeter for light waves of various wavelengths.

Unusual color and color of water limits its use and forces to look for new sources of water supply. However, water from new sources may turn out to be epidemiologically dangerous and contain toxic substances. In addition, an increase in the color and color of water may indicate its contamination with industrial wastewater. Highly colored water can be biologically active due to humic organic matter... There are no convincing data on the effect of high color water on human health in the literature. But it is known that as a result of the action of humic acids, the permeability of the intestinal walls for the cations of Ca, Mg, Fe, Mn, Zn, and sulfation increases by 50-100%. Finally, chromaticity is an indicator of the effectiveness of water purification (discoloration) at a wastewater treatment plant.

Turbidity- the natural property of water due to the presence of suspended solids of organic and mineral origin (clay, silt, organic colloids, plankton, etc.) in it.

The opposite characteristic of water is transparency, that is, its ability to transmit light rays. The more suspended solids in the water, the higher its turbidity, that is, the less transparency.

The Snellen method was proposed to quantify the transparency of water. Water is poured into a flat-bottomed cylinder. A standard font is placed at a distance of 4 cm from the bottom. The letters are 4 cm high and 0.5 mm thick. The water is drained from the cylinder until the letters can be read through its column. The height of this column (in centimeters) characterizes the transparency of the water. In the opinion of the consumer, transparent water, when measured by the Snellen method, has a transparency of at least 30 cm.

A simulated kaolin scale has been proposed to measure the level of turbidity in water. This is a set of suspension of white clay (kaolin) in distilled water. The content of kaolin in suspensions ranges from 0.1 to 0.5 mg / l. The turbidity of water is measured in milligrams per liter by comparing its absorbance with the density of kaolin standard solutions. Previously, these comparisons were made visually. Today, nephelometers, spectrophotometers and photocolorimeters are used.

If the water, which consumers rated as clear, is evaluated on a simulated kaolin scale, it turns out that its turbidity does not exceed 1.5 mg / l. If the overwhelming majority of consumers believe that the water is opaque, then its turbidity exceeds 1.5 mg / l. That is why the state standard for drinking tap water states that its turbidity should not exceed 1.5 mg / l.

Turbidity is closely related to other properties of water, primarily color, smell and taste. So, humic substances, which determine the color of water, make it cloudy (due to the colloidal fraction), give it a natural smell and taste. A reddish color indicates the presence of iron hydroxide (III) in the water. Such water is cloudy, with a specific astringent taste.

Turbidity affects microbiological indicators of water quality. Most microorganisms are sorbed on the surface or in the middle of suspended particles, the organic and inorganic substances of which protect bacteria and viruses. Literature data indicate that disinfection of turbid water with chlorine for 30 minutes, even with residual, free active chlorine at a level of 0.3-0.5 mg / l, is ineffective against intestinal bacteria and viruses (for example, pathogens of hepatitis A). At the same time, clarification and discoloration of water at treatment facilities, aimed at removing suspended and humic substances, help to remove 90% of bacteria.

It has been established that chlorinated turbid water can be hazardous to health due to the formation of organochlorine compounds - toxic and even carcinogenic. These are chlorophenols, chlorocyanes, trihalomethanes, chlorinated polycyclic aromatic hydrocarbons, and polychlorinated biphenyls.

Cloudy, cloudy water causes a feeling of disgust in a person. This limits its use and forces us to look for new sources of water supply, the water in which may turn out to be epidemiologically dangerous and contain harmful substances. Turbidity of water indicates its contamination with organic and inorganic substances that can be harmful to human health or form harmful substances during reagent water treatment (for example, chlorination). Turbidity is an indicator of the efficiency of water clarification at a wastewater treatment plant. And, finally, turbidity is one of the factors affecting the efficiency of water disinfection, that is, the efficiency of cleaning it from pathogenic bacteria and especially enteroviruses.

Turbid water is always suspicious in epizootic and sanitary terms, as it creates favorable conditions for microorganisms. Turbidity of water is caused by the presence of undissolved and colloidal substances in it.

Qualitatively, turbidity is characterized by the words: transparent, slightly opalescent, opalescent, slightly turbid, turbid, very turbid. Quantitatively - by the content of suspended solids in water, expressed in mg / l. In this case, the test tube with the test water is compared with standard ampoules of the kaolin suspension.

In the field, a test tube with a diameter of 14-16 mm made of colorless glass is filled with analyzed water to a height of 10-12 cm and viewed against a black background. Turbidity of water should not exceed 1.5 mg / l, as an exception up to 2 mg / l.

3. Chemical properties of water.

Purpose of the lesson: to master the methods of determination: pH, dry residue, hardness, chlorides, sulfates, and other chemical indicators.

The chemical properties of water include: dry residue, pH, hardness, sulfate and chloride content, nitrogen-containing substances content, water oxidizability and oxygen content in it, mineral content and other indicators.

3.1. Determination of dry residue in water

The dry residue of water is what remains from the evaporation of one liter of water. The method includes filtration, evaporation and drying of the residue at 110 0 С to constant weight.

According to the sanitary standard, the dry residue in drinking water should not be more than 1000 mg / l., As an exception, up to 1500 mg / l.

3.2. Determination of the active reaction (pH) of water (pH)

The pH of the medium is understood as the presence of free, active hydrogen ions. Their concentration is usually expressed as a pH value from 1 to 14.

A pH value of 7 corresponds to a neutral medium, less than 7 - acidic, more than 7 - alkaline.

The pH value is determined by electrometric and colorimetric methods.

For an approximate determination of the pH of water, various indicator (litmus) papers are used, as well as a universal indicator with a comparison scale.

In the field, the reaction (pH) of water is determined by the color change of litmus paper. A blue litmus test means that the reaction is alkaline (pH> 7.0), reddening of the blue means that the reaction is acidic (pH< 7,0).

For analysis with a universal indicator, 3-5 ml of the sample is poured into a test tube previously rinsed with the test water and 2-3 drops of the indicator are added. The contents are stirred and the pH value is determined by the color of the solution:

Red-pink - 2,

Red-orange - 3,

Orange - 4,

Yellow-orange - 5,

Lemon yellow - 6,

Yellow-green - 7,

Green - 8,

Blue-green - 9,

Purple - 10,

According to the sanitary standard, the pH of drinking water should be in the range of 6.0-9.0.

3.3. Determination of water hardness

Water hardness is mainly determined by the presence in it of carbonate, chloride, sulfate, phosphate, nitrate salts of magnesium and potassium.

Water hardness can sometimes be an indicator of organic contamination. As a result of the decay of organic matter, carbon dioxide is formed, which can leach calcium and magnesium compounds from the soil.

When water is polluted with alkaline waters, its hardness increases. For household and technical purposes, hard water is undesirable.

There are three types of hard water: general, removable (carbonate) and permanent.

Total hardness - the hardness of raw water, due to the total amount of calcium and magnesium cations.

Disposable - the hardness of raw water, due to calcium and magnesium bicarbonates, which, when boiled, precipitate in the form of scale.

Constant - depends on the presence of sulfate, chloride and other salts of calcium and magnesium. Constant hardness remains after one hour boiling.

Water hardness was previously expressed in degrees. 1 mEq / L is 2.8 degrees.

Determination of removable (carbonate) hardness

The principle of the method is based on titration of carbonates with hydrochloric acid in the presence of methyl orange indicator.

The method is based on the following reaction:

Ca (HCO 3) 2 + 2HC1 → CaCl + 2CO;

Mg (HCO 3) 2 + 2HCl → MgCl + 2CO;

Dishes and reagents:

0.1 n. hydrochloric acid solution;

1% aqueous solution of methyl orange,

measuring pipettes;

conical flasks with a capacity of 150 ml;

Determination progress... 100 ml of test water is poured into a conical flask with a capacity of 150 ml, 2 drops of methyl orange are added and titrated with 0.1 N hydrochloric acid solution until the yellow color turns slightly pink. Titration is carried out three times and the average is calculated. For control, place a flask with the same water with the addition of two drops of methyl orange. The calculation is made according to the formula:

X = ---------------------, where:

X - carbonate hardness, in mg-eq / l;

a - the amount of 0.1 N. HCI solution consumed for titration, ml;

0.1 - titer of hydrochloric acid;

k - correction factor for titer 0.1 N. HCI solution;

1000 - conversion factor for 1 liter;

V is the volume of the investigated water, ml.

Determination of the total hardness of water

Into the same flask from the burette is poured 20 ml of an alkaline mixture (equal parts of 0.1 N Na 2 CO 3 solution and 0.1 N NaOH solution and boiled for 3 minutes).

Then the liquid is poured into a measuring cylinder (or a 200 ml volumetric flask), added with distilled water to 200 ml, stirred and filtered.

100 ml of filtrate is poured into a flask, 2 drops of methyl orange indicator are added and titrated with 0.1 N. hydrochloric acid to a slightly pink coloration.

The calculation is made according to the formula:

X = 20 × a × 2, where:

X - total hardness, mg-eq / l;

20 - the amount of alkaline mixture, ml;

a - the amount of acid used for titration, ml;

2 is a factor.

Constant stiffness

Determine it by the difference between the total and carbonate hardness.

According to the sanitary standard, the total water hardness should be no more than 7 (10 *) mg-eq / l.

* Note: the value indicated in brackets can be set by the order of the chief state sanitary doctor of the region for a specific water supply system based on the sanitary and epidemiological situation and the applied water treatment technology.

For watering animals, it is allowed, depending on the zone, to use water with hardness (meq / l): for cattle -10-18, sheep -20-25, pigs - 8-14, horses -10-15.

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Turbidity of water is caused by the presence in water of fine impurities and suspended particles, which are insoluble substances of organic and inorganic origin. Very often, turbidity is closely related to the iron and manganese content of the water. In addition, turbidity can be caused by aluminum hydroxides, insoluble carbonate compounds. Turbidity is most significantly subject to change in wells. This is due to the ingress of technogenic pollutants and hardly soluble substances into the groundwater.
If you observe red water in a well or well, this is due to the formed oxides of iron and manganese. In addition, clay and lime suspensions are also often the cause of high water turbidity.
In Russia, the turbidity of water is determined turbometrically (by the attenuation of the light passing through the sample) by comparing the samples of the investigated water with standard suspensions. Measurement results are usually expressed in EMF - Formazin turbidity units.

According to SanPiN 2.1.4.1074-01 “Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems. Quality control "MPC for turbidity: 2.6 - 3.5 EMF

There is also another unit of measurement - kaolin. In accordance with the hygienic requirements for the quality of drinking water, the turbidity for kaolin should not be higher than 1.5 mg 3 / dm 3.
Turbidity testing is performed in each of the assays featured on our vodalab website

Traditionally, a suspension of kaolin (clay) was used as a standard suspension, in which case they say: "Turbidity in kaolin mg / l", meaning how many milligrams of kaolin per liter (or cubic decimeter) were added to obtain identical turbidity in comparison with the test sample.

Nowadays, formazin (polymer) is most often used to determine turbidity, while turbidity is measured in EM / liter (units of turbidity per liter)

In this case, they say: "... units of turbidity by formazin (EMF)"

Turbidity in water analysis

Let's look at an example from practice:

I have an analysis from one of the clients. Here is a link to it: ".doc" you can download the whole analysis, but I suggest looking at the picture first:

So this is what we see:

1. Turbidity, EMF - 37 according to the research result. At a rate of 2.6. in the last column of GOST 3351-74 is state standard for organoleptic examination of drinking water by color, smell, taste and turbidity.
2. Look further - Total iron - 5.79 mg / l at a rate of 0.3 mg / l. A lot, yes?
3. And now the most important thing - Iron 2+ bivalent dissolved iron - 0.01 - practically none.

From this I conclude that all the iron was almost completely oxidized in the bottle while the water was being transported to the laboratory, while the water was waiting in the laboratory for its turn for research. And the iron passed into a trivalent state - colloidal - very small particles that cannot be seen with the eye, but the turbidity of the water is clearly visible.

If you add a couple of drops of coagulant to this water, the colloids will quickly stick together and the suspension will settle to the bottom. You can also just wait in the water aerobic iron bacteria will start up, which will "eat" the iron, as a result of which it will again precipitate in the form of flakes.

Now that you know everything about the turbidity of water, it will be interesting for you to look at to consolidate the material, so to speak, here is this short news video from the archive:

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