FEDERAL SUPERVISION SERVICE
IN THE FIELD OF NATURE MANAGEMENT
QUANTITATIVE CHEMICAL ANALYSIS OF WATER
MEASUREMENT METHODS OF MASS
CONCENTRATIONS OF SUSPENDED SUBSTANCES AND
CANCINED SUSPENDED SUBSTANCES IN
SAMPLES OF DRINKING, NATURAL AND WASTE WATER
BY GRAVIMETRIC METHOD
PNDF 14.1:2:4.254-2009
The technique is approved for government purposes
environmental control
MOSCOW 2009
(2012 edition)
The technique has been reviewed and approved by the federal budgetary institution"Federal Center for Analysis and Assessment of Technogenic Impact" (FBU "FCAO").
Developer:
Analytical Center CJSC ROSA
1 AREA OF USE
Real normative document establishes a methodology for quantitative chemical analysis various types water, with a circuit for measuring the content of suspended and calcined suspended solids using the gravimetric method. The methodology applies to the following objects of analysis: drinking water; natural waters, including surface and underground sources water supply; industrial, domestic, stormwater and treated wastewater. The technique can be used to analyze samples of snow cover and melt water.
The measurement range for the content of suspended and calcined suspended solids is from 0.5 to 5000 mg/dm 3 .
The duration of analysis of one sample for the content of suspended substances is 14 hours, a series of 10 samples is 15 hours.
The duration of analysis of one sample for the content of calcined suspended substances is 17 hours, a series of 10 samples is 18 hours.
A flow diagram of the analysis is given in the appendix.
Significant amounts of oils and fats interfere with the determination, therefore, when taking a sample, it must be ensured that no surface film or pieces of fat get into it. If, nevertheless, the sample delivered to the laboratory contains visible fat or oil on the surface, then they are removed before analysis. Remove fat from the surface of the sample with a spoon or spatula, and oil with a piece of filter paper.
Contaminants in the form of single inclusions, for example, small sticks, grass, etc., are also removed.
2 REGULATORY REFERENCES
4 MEASUREMENT METHOD
The method for determining suspended substances is based on isolating them from a sample by filtering water through a pre-weighed paper or membrane filter and determining the weight of the sediment on the filter, dried to a constant weight at (105 ± 2) °C.
The method for determining calcined suspended substances is based on isolating them from a sample by filtering water through a pre-weighed paper or membrane filter, drying to constant weight at (105 ± 2) °C and then determining the weight of the sediment on the filter, calcined to constant weight in a muffle furnace at (600 ± 15) °C.
5.1.2 Laboratory scales with a maximum load of 210 g, high accuracy class according to GOST R 53228.
5.1.3 Laboratory funnels, V-56-80 XS, V-75-110 XS according to GOST 25336.
5.1.4 Homogenizer, for example, IKA brand from Labortechnic (Germany), model Ultra-Turrax T 25 or any other.
5.1.5 Distiller or installation of any type for producing distilled water in accordance with GOST 6709 or water for laboratory analysis of purity level 2 in accordance with GOST R 52501.
5.1.6 Conical flasks with a capacity of 500 and 1000 cm 3 according to GOST 25336.
5.1.7 Muffle furnace with a working chamber lined with a ceramic muffle, providing a temperature of (600 ± 15) °C.
5.1.8 Metal tweezers with sharp ends.
5.1.10 Filtration installation with a vacuum pump.
5.1.11 Bottles with a ground-in stopper (for storing reagent solutions).
5.1.12 Household refrigerator, providing storage of samples at a temperature of (2 - 10) °C.
5.1.13 Measuring cylinders with a capacity of 500 and 1000 cm 3 according to GOST 1770, 2 accuracy classes.
5.1.14 Drying cabinet for general laboratory purposes, providing a temperature of (105 ± 2) °C.
5.1.15 Crucible tongs.
5.1.16 Any spatula or spoon.
It is allowed to use measuring instruments, auxiliary equipment, and laboratory glassware with similar or better metrological and technical characteristics.
5.2 Reagents and materials
5.2.1 Distilled water according to GOST 6709 or for laboratory analysis according to GOST R 52501 (2nd degree of purity), (hereinafter referred to as distilled water).
5.2.3 Iron (III) chloride (ferric chloride), 6-water according to GOST 4147, part, saturated solution (for marking bottles).
5.2.4 Paper filters “blue tape” with a diameter of 15 cm, with an ash mass of (0.0016 - 0.0020) g according to TU 6-09-1678 or according to TU 2642-001-42624157.
5.2.5 Membrane filters with a pore diameter of 0.45 microns.
It is allowed to use reagents of higher qualification, as well as materials with similar or better characteristics.
6 CONDITIONS FOR SAFE WORK
6.1 When performing analyses, it is necessary to comply with safety requirements when working with chemical reagents in accordance with GOST 12.1.007.
6.2 When working with equipment, it is necessary to comply with electrical safety requirements when working with electrical installations in accordance with GOST R 12.1.019 and safety requirements when working with muffle furnace in accordance with the operating instructions.
6.3 Organization of occupational safety training for workers should be carried out in accordance with GOST 12.0.004.
6.4 The laboratory premises 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.
7 OPERATOR QUALIFICATION REQUIREMENTS
Persons proficient in gravimetric analysis techniques are allowed to perform measurements and process their results.
8 CONDITIONS FOR PERFORMING MEASUREMENTS
When performing measurements in the laboratory, the following conditions must be met:
|
air temperature |
from 20 °C to 28 °C |
|||||||||||||||||||||||||||||||||
|
relative humidity |
no more than 80% at 25 °C |
|||||||||||||||||||||||||||||||||
|
mains voltage |
12 PROCESSING OF MEASUREMENT RESULTSWhere X 1 - suspended solids content, mg/dm3; m 2 - mass of a bottle with a membrane or paper filter with suspended solids, g; m 1 - weight of the bottle with a prepared membrane or paper filter, g; V
Where X 2 - content of calcined suspended solids, mg/dm 3 ; m 4 - mass of the crucible with the residue after calcination, g; m 3 - mass of the calcined crucible, g; m- mass of paper filter ash (indicated on the filter packaging), g; Note - When using a membrane filter, the mass of ash is not taken into account. V- volume of water sample taken for analysis, dm 3. 13 REGISTRATION OF MEASUREMENT RESULTS X (section 5).The measurement result is considered acceptable if the following conditions are met:
Reproducibility limit values ( R) are given in the table. 15 CONTROL OF ACCURACY OF MEASUREMENT RESULTSMonitoring the accuracy of measurement results when implementing the technique in the laboratory is carried out using working samples. When regularly performing analyzes according to the method, the stability of the standard deviation of intra-laboratory precision is monitored using control charts at intervals established in the laboratory. Calculation of control limits is carried out in accordance with the recommendations of GOST R 50779.42 and GOST R ISO 5725. When carrying out occasional analyzes according to the method, operational monitoring of the repeatability indicator is carried out. To do this, one sample from a series of working samples is carefully homogenized, divided into two parts and analyzed under repeatable conditions. Next, the results are evaluated by . Table 2 - Limits of repeatability and reproducibility of measurement results (with probability R = 0,95)
| |||||||||||||||||||||||||||||||||
One of the most important indicators sanitary-chemical analysis when calculating the degree of wastewater treatment is the amount of suspended solids.
Suspended substances are an indicator characterizing the amount of impurities that are retained on a paper filter when filtering a sample, measured in mg/l and mg/dm3.
The amount of suspended solids determines the amount of sludge formed during wastewater treatment. These data are used in the design of primary settling tanks.
Why are suspended solids in wastewater dangerous? When released into bodies of water, they clog aquatic environment. Mineral particles enter the gills of fish and injure them. Large mechanical impurities and resins cause secondary pollution when they enter water bodies.
Light fractions of resins from suspended substances in the form of an emulsion are in water and form a surface film that envelops aquatic organisms and interferes with their movement.
Maximum permissible concentrations of suspended substances for discharge into water bodies:
- 0.25 mg/dm3 to the background content of suspended substances for water bodies of fishery importance of the highest and 1st category;
- 0.75 mg/dm3 for water bodies of fishery importance of category 2.
Goal of the work: determination of the amount of suspended solids in wastewater samples.
Suspended solids present in natural waters consist of particles of clay, sand, silt, suspended organic and inorganic substances, plankton, and various microorganisms. The concentration of suspended particles is associated with seasonal factors and the flow regime and depends on snow melting, rocks composing the riverbed, as well as anthropogenic factors such as agriculture, mining, etc.
Suspended solids affect water clarity and light penetration, temperature, dissolved components of surface waters, adsorption of toxic substances, as well as the composition and distribution of sediments and the rate of sedimentation. Water containing a lot of suspended particles is not suitable for recreational use for aesthetic reasons.
Coarsely dispersed impurities are determined by the gravimetric method after their separation by filtration through a “blue ribbon” filter (mainly for samples with less transparency 10 cm).
Sample selection.The volume of water samples must be at least 2000 cm3. The water sample is not preserved. The determination is performed no later than one day later.
Equipment and reagents
Laboratory scales; drying cabinet; desiccator; paper filters “white tape” and “blue tape”; aluminum bottles; glass funnels; measuring cylinders with a capacity of 50, 100 cm 3; heat-resistant glasses; distilled water.
Completing of the work
1. Before analysis, the water sample in the bottle is shaken vigorously, then quickly poured into measuring cylinders of 50-2000 cm 3, depending on the expected content of suspended particles.
2. Place the prepared weighed filter into a glass funnel and filter the selected volume of sample through it (using a “blue ribbon” filter).
3. Rinse the measuring container several times with large portions of the filtrate, then transfer this filtrate to the filter, wash the filter with 1–2 cm 3 of distilled water to wash the precipitate from the filtrate.
4. The filter with the sediment is transferred to a bottle and dried for 2 hours at 105±2°C. Close the bottle with a lid and cool in a desiccator for 30 minutes.
5. Weigh the bottle with the filter and sediment. If necessary (weight gain more than 250 mg), repeat drying for 30 minutes. If the difference in mass is no more than 0.0002 g , drying is considered complete.
|
Where m 1 – weight of the bottle with filter and sediment, mg; m 2 – weight of the bottle with a clean filter, mg; V– volume of analyzed water, cm3. |
Table. Form for recording the results of the analysis of the amount of suspended solids
|
Try |
Place of selection |
Weight of bottle with clean filter, mg |
Weight of the bottle with filter and sediment, mg |
Water sample volume, cm3 |
|
6. Draw conclusions based on the results of the analysis of the amount of suspended substances.
MINISTRY OF HOUSING AND COMMUNAL SERVICES OF THE RSFSR
Order of the Red Banner of Labor
Academy of Public Utilities
them. K.D. Pamfilova
RECOMMENDATIONS
TO IMPROVE CONTROL METHODS
QUALITIES
NATURAL AND WASTEWATER
USING VLADIPOR MEMBRANES
TYPE MFA-MA
Department of Scientific and Technical Information of AKH
Moscow 1990
Recommendations for the use of Vladipor filter membranes of the MFA-MA type are outlined for determining color, turbidity, dry residue, dissolved and suspended substances, the content of hydrobionts, iron bacteria and viruses in water.
The recommendations were developed by the Scientific Research Institute of Municipal Water Supply and Water Purification, AKH named after. K.D. Pamfilova (Candidate of Medical Sciences N.A. Rusanova, Candidates of Chemical Sciences I.V. Seryakova and O.Ya. Antonova) and are intended for laboratories of PUVKH and SES.
The development and organization of industrial production of Vladipor filter membranes of the MFA-MA No. 1-10 brands and filter devices for microbiological analysis of water have opened up the prospect of widespread use in the country progressive method membrane filters.
IN last years The Research Institute of Municipal Water Supply and Water Purification has developed “Recommendations for the use of Vladipor filter membranes of the MFA-MA brand for sanitary and bacteriological analysis of water,” which were included in Change No. 1 to GOST 18963-73 “Drinking water. Methods of sanitary and bacteriological analysis". In addition, the Research Institute of KVOV together with the Rosvodokanalnaladka trust and I Moscow Medical Institute named after. THEM. Sechenov developed “Recommendations for improving the method of sanitary and bacteriological control of wastewater quality.”
However, sanitary and bacteriological analysis does not exhaust the possibilities of using the membrane method in studying water quality. The method is suitable for studying unsanitary indicator bacteria at the stages of physical-chemical, organoleptic, hydrobiological and virological analyzes of water quality.
Based on the work carried out at the institute during 1985 - 1987, recommendations were developed for the use of Vladipor membranes of the MFA-MA type in determining color and turbidity, which were included in Amendment No. 1 to GOST 3351-74 “Drinking water. Methods for determining taste, smell, color and turbidity"; Recommendations have also been developed for the use of these membranes in determining dry residue, dissolved and suspended substances, the content of hydrobionts, iron bacteria and viruses in water.
The laboratories of the Northern and Western waterworks of Moscow, the central laboratory of the PUVKH of Yaroslavl, the laboratory of the wastewater treatment plant of Khodorov and the laboratory of the physical and chemical wastewater treatment station of Radviliskis (Lithuanian SSR) took part in the testing of the recommendations.
GENERAL PROVISIONS
1. “Vladipor” membranes of the MFA-MA grades No. 1-10 are produced by the Kazan PA “Tasma” named after. V.V. Kuibyshev (TU 6-05-1903-81).
To study water quality, membranes with a disk diameter of 35 are used.± 2 mm.
2. The filter device into which the membrane is mounted is selected taking into account the purpose of filtration. If a suspension isolated from a water sample is examined, it is most convenient to use a filter apparatus for microbiological water analyzes (AF index), produced by the factories of the Ministry of Housing and Utilities of the RSFSR. Similar devices available in water supply laboratories can be used, as well as filter systems mounted from a Bunsen flask, a Seitz funnel (or other suitable funnel), or a water-jet (or other vacuum-creating) pump. If the filtrate is to be examined, the filter device must have a container to collect it. The above-mentioned Bunsen flask system can be used. Just like the Seitz funnel, you can mount a filter section with it, removed from the common manifold of the filter apparatus for microbiological analyzes of water (the hole where it was attached to the apparatus should be closed with a rubber stopper).
3. Membranes are prepared for use by boiling as follows: a “milk guard” or stainless steel mesh is placed at the bottom of the vessel in which boiling is carried out (beaker, enamel pan, etc.) to limit violent boiling. Distilled water is poured into this vesselin a small volume, limiting the free rotation of the filter membranes in it, but sufficient for the filter membranes to be covered with water when immersed. The temperature of the distilled water in the vessel is brought to 80 - 90 °C and the heat is reduced. After this, filter membranes are placed on the surface of the water one at a time, visually checked for the absence of cracks, holes, bubbles, etc. The water with the membranes placed in it is slowly brought to a boil and boiled for low heat for 10 - 15 minutes. This water is then drained and replaced with a small amount (to cover the filter membranes) of distilled water. After this, the filter membranes are ready for use. Repeated boiling of the filter membranes is not required.
If the work does not require sterility, the duration of boiling can be reduced to 3 - 5 minutes. In this case, less shrinkage of the filters occurs, and their ovality is somewhat less pronounced. When using membranes in handicraft, home-made filtering devices made according to the Rublevsky type, this can have a positive effect.
DETERMINATION OF COLORITY
The color of water is determined photometrically - by comparing samples of the test liquid with solutions that imitate the color of natural water.
One of the stages of analysis is filtering the test water and control distilled water through a membrane filter. Use boiled Vladipor filter membranes of the MFA-MA brands No. 5, 6, 7 and 8 (any of the numbers mentioned) with filter devices in which the filtrate can be collected.
Other stages of preparation for analysis and determination of color are carried out in accordance with GOST 3351-74 “Methods for determining taste, smell, color and lightness” (clause).
DETERMINATION OF TURBIDITY
Water turbidity is determined photometrically - by comparing samples of the test water with standard suspensions.
One of the stages of analysis is filtering the test water in order to obtain a filtrate used as a control liquid when determining the optical density of the test water sample.
Use boiled Vladipor filter membranes of the MFA-MA brands No. 5, 6, 7 and 8 (any of the numbers mentioned) with filter devices in which filtrate can be collected.
Other stages of preparation for analysis and determination of turbidity are carried out in accordance with GOST 3351-74 “Methods for determining taste, smell, color and turbidity” (clause 5).
DETERMINATION OF SUSPENDED SUBSTANCES
Suspended solids are contaminants that are insoluble in water. They are determined gravimetrically after a delay on the filter.
The choice of method for retaining suspended solids depends on their nature. The method using membrane filters is used when there is a wastewater or natural water fine suspended matter, which is not retained by ash-free filtrates, and in cases where the amount of suspended solids in water is below 10 mg/l. This method guarantees the retention of suspended substances whose particles have a size of 1 micron and above.
A contraindication to the use of the membrane filter method for determining suspended solids is the presence of hygroscopic suspended solids in the wastewater and, less commonly, natural water under study, the retention of which on the membrane filters prevents the membranes from being brought to a constant mass upon drying, which is required during the analysis process.
Use boiled Vladipor membranes of the MFA-MA brand No. 9, 10. Excess moisture from the membranes after boiling is removed by blotting them on filter paper. The membranes are transferred to numbered bottles and dried to constant weight at 105± 2 °C for 30 - 45 min. When drying, the numbered lid from the bottle is placed next to the bottle. After 45 minutes, the bottle is closed with an appropriate lid, transferred to a desiccator for 20-30 minutes to cool and weighed.
The sample is analyzed no later than 1 day without preservation. The thoroughly mixed test water is transferred in several stages into a measuring container.
With a suspended solids content of 5 - 10 mg/dm 3, the volume of the filtered sample is 0.2 - 0.4 dm 3; if suspended substances are in the range of 10 - 50 mg/dm 3, the sample volume is 0.2 - 0.5 dm 3. The error of this determination is within the acceptable range: does not exceed 20% (at p = 0.095). When the concentration of suspended solids is more than 50 mg/dm 3, the sample volume is 0.05 dm 3. Moreover, the determination error is even smaller: 5 - 10%.
Before filtration begins, the dried filter is moistened in distilled water and placed in the filter device. Filter a measured volume of water under vacuum. If necessary, you can speed up the process by filtering the sample through several sequentially replaced membranes; you can pour the sample from the cylinder without additional stirring into a filter funnel in small portions. Shake the last portion well and then filter. The cylinder and funnel walls are rinsed several times with small volumes of distilled water; the resulting suspension is filtered.
At the end of filtration, the membrane filter with the sediment is dried in an open bottle for 45 - 60 minutes, cooled,closing the bottle with a lid, weigh it in a desiccator. After this, re-drying is carried out for 15 - 20 minutes and re-weighing after cooling. Drying to a constant mass is considered achieved if the difference between the weighing masses after the first and after repeated drying (both filters without sediment and filters with sediment) does not exceed 0.0002 g.
The calculation is made according to the formula
where X - content of suspended substances, mg/dm 3 ;
m 1 - weight of the bottle with filter and sediment, mg;
m 2 - weight of the bottle with a clean filter, mg;
V - volume of the analyzed sample, cm 3.
Example . A sample of 500 cm 3 of water was filtered. The weight of the bottle with filter and suspension is 21065.8 mg, the weight of the bottle with a clean filter is 21054.4 mg. Suspended solids content
mg/dm3.
DETERMINATION OF DRY RESIDUE, DISSOLVED SUBSTANCES
The term “Dry residue” is used in the study of natural (GOST 17.1.3.03-77 “Rules for the selection and assessment of the quality of sources of centralized household and drinking water supply”) and drinking water (GOST 18164-72 “Drinking water. Method for determining the content of dry residue”). The term “Dissolved substances” is used in the study of wastewater (“Methodology for technological control of the operation of urban sewage treatment plants.” - M.: Stroyizdat, 1977). These terms denote the same general indicator of water quality, which determines the content of non-volatile dissolved and colloidal impurities of an inorganic and organic nature. This is the residue obtained by evaporating filtered test water to dryness, dried at a temperature of 103 ° C, and studied gravimetrically.
The first stage of analysis is filtering the water sample under study, which is carried out through a paper or membrane filter in order to free the sample from suspended impurities. The use of membrane filtration is indispensable if finely dispersed suspended matter is present in the water.
Use boiled Vladipor filter membranes of the MFA-MA brands No. 9, 10 with filter devices in which the filtrate can be collected. The volume of the tested drinking water sample is at least 300 cm 3 , and the volume of purified municipal waste liquid is at least 100 cm 3 . Samples are not preserved; they are examined immediately or no later than 24 hours later.
The resulting filtrate should be visually transparent. It is evaporated, dried and examined gravimetrically in accordance with current rules (GOST 18164-72 “Drinking water. Method for determining the content of dry residue”, “Methodology for technological control of the operation of municipal sewerage treatment facilities”).
HYDROBIOLOGICAL ANALYSIS
When analyzing water, sediments from structures and loading filters for the content of algae cells (phytoplankton, phytobenthos, phytoperiphyton), small forms of zooorganisms (ciliates, rotifers, etc.), in most cases, preliminary concentration of the organisms is required.
Use “Vladipor” filter membranes prepared by boiling, grades MFA-MA No. 9, 10.
The volume of filtered samples is dictated by the objectives of the study.
During the period of algal bloom, samples should be filtered without pouring the entire test volume into a filter funnel, but proportionally (50 - 100 ml each), first draining the upper settled part of the sample. The last 1 - 2 portions are filtered, after shaking well. The container is rinsed with 10 ml of water, which is also filtered. If filtration through one filter slows down during operation, the next portion of the sample can be filtered through a new filter. The retained aquatic organisms are washed off into the volume of water required for the study from all filters used to filter this sample.
In the resulting concentrate, the qualitative and quantitative composition of hydrobionts is examined using microscopy.
DETERMINATION OF IRON BACTERIA
Direct microscopy of iron bacteria concentrated on a filter membrane is one of the simplest and fastest methods for assessing quality composition and concentrations of iron bacteria in natural and drinking water, in sediments and fouling of water supply systems.
Use boiled Vladipor filter membranes of the MFA-MA brands No. 5, 6, 7 and 8.
The volume of the test sample depends on the concentration of iron bacteria and other suspended matter in it (1 - 1000 cm 3).
After finishing filtering, the membranes are dried and labeled. If necessary, the retained iron bacteria are stained. The entire membrane or a separate segment is mounted on a glass slide.
To clear the membranes, Vaseline oil is used. After this, microscopy of iron bacteria is performed.
VIROLOGICAL STUDY
In virological studies of drinking, natural, waste water carried out on cell cultures, a prerequisite is the elimination (limitation) of the negative impact on the cells of bacteria contained in the same water samples as viruses.
Boiling-sterilized Vladipor filter membranes of the MFA-MA No. 1 brand are used to remove bacterial suspension from samples.
The volume of the filtered sample is 5 - 10 cm3. Processing larger volumes of samples is difficult due to the length of the filtration process through these membranes.
Contamination with bacterial flora can be significantly reduced by filtering water samples through boiling-sterilized Vladipor filter membranes of the MFA-MA brands No. 2, 3, 4.
Membranes are used with filter devices in which filtrate can be collected. In this case, the filter funnel, the container for collecting the filtrate, and its stopper must be pre-sterilized.
The use of membranes does not eliminate the need to use antibiotics when inoculating samples into cell cultures.