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Standardization and regulation of water quality in reservoirs. Wastewater treatment, its composition and types

Head Pond. Serves as a source of water supply and for water storage. Sometimes commercial fish or planting material is grown in it. Used all year round.
Spawning. Used in May-June for spawning spawners and obtaining fish larvae.
Fry. Serve for growing larvae to the fry stage (small formed fish) weighing 0.1-1.0 g. Period of use - 20-30 days in May-June.
Growing up. They grow young of the year, i.e. fish of this summer, to a standard weight of 25-30 g in the period from May to October.
Wintering ponds. Serve for keeping fingerlings and breeders in winter. Usage time in middle lane Russia - from October to April.
Foraging. They are used for growing commercial fish. They are stocked with yearlings (overwintered fingerlings) in the spring, most often in April. Commercial fish is caught in September-November.
Summer queens. They contain breeding and replacement stock. Producers are sexually mature individuals, and replacements are fish selected for a number of indicators as future producers, but have not yet reached sexual maturity. The time of use for this category of ponds is from April to October.
Cages. Ponds of a small area in which marketable fish are kept from autumn to spring to extend the timing of the sale of fish.
Insulating. Used to keep sick fish. Can be used all year round.

Quarantine. They are used to keep fish imported from other farms. The duration of quarantine is usually 1 month.

In table 7 presents the main regulatory characteristics of all categories of ponds for specialized fish farms.

Table 7. Main characteristics of ponds of various categories

Name of the ponds	Area, ha	Depth, m average / maximum	Water exchange, days	Time, days		Aspect Ratio
				filling	descent
Head ones	by relief	by relief	+	up to 30	up to 30	by relief
Wintering	0,5-1,0	1,8/2,5	15-20	0,5-1,0	1,0-1,5	1:3
Spawning	0,05-0,1	0,6/1,0	-	0,1	0,1	1:3
Fry	0,2-1,0	0,8/1,5	-	0,2-0,5	0,2-0,5	1:3
Growing up	10-15	1,0-1,2/1,5	-	10-15	3-5	by relief
feeding	50-100	1,3-1,5/2-2,5	-	10-20	up to 5	by relief
Summer queen	1-10	1,3-1,5/2-2,5	-	0,5-1,0	0,5	1:3
cages	0,001-0,05	1,5/2,0	0,1	0,1	0,1	1:3
Insulating	0,2-0,3	1,8/2,5	15-20	0,5-1,0	1,0-1,5	1:3
Quarantine	0,2-0,3	1,5/2,0	-	0,5-1,0	1,0-1,5	1:3

All ponds on the farm are located in a certain sequence. Thus, wintering facilities are located near the dam so that the path from the water source to the ponds is the shortest in order to avoid freezing or hypothermia of the water. Spawning - near fry and nursery fish to reduce on-farm transportation of fish. Feeding ponds are built downstream of the river behind nursery ponds. Quarantine and isolation ponds are located at the farthest point of the farm to reduce the possible risk of disease spread. In addition to full-system fish farms, there are fish hatcheries. They grow fish stock - fingerlings and yearlings, which are sold to so-called feeding farms. Fish hatcheries have all categories of ponds listed above, with the exception of feeding ones. In feeding farms there are only feeding ponds. By purchasing planting material from fish hatcheries, marketable fish are grown there. In addition, there are breeding farms that carry out selection and breeding work and sell producers and replacement stock to fish hatcheries and full-system farms.

Theoretically, a farm fish farm can be a full-system, breeding, feeding and fish nursery. However, the main specific feature farms is the limited availability of land, water and human resources. Therefore, the fish farm should be compact and, in addition to the minimum construction cost, as cheap as possible to operate, not requiring much work force. This can be achieved by choosing the right type of farm. A small group of farmers, often consisting only of members of one family or relatives, is simply not able to operate a full-system or breeding farm with big amount ponds and a variety of technological operations. In such a situation, the optimal option seems to be when the fish farm has ponds of only one category, although there may be not one, but several ponds themselves. These can be feeding, nursery or ponds used for paid fishing. In the following chapters we will talk about the technologies most suitable for commercial fish farms, fish hatcheries and commercial recreational fisheries. As for the recommended sizes of ponds, you need to take into account that the fish breeding standards given in table. 7, were adopted almost a quarter of a century ago and were developed exclusively for state fish farms, when the thought of any possible restrictions was not even allowed and when many projects suffered from gigantomania. Meanwhile, over the past time there have been significant changes both in the economy in general and, in particular, in fish farming. From the point of view of needs and realities today and the development of fish farming technologies, it seems unjustified to build, for example, feeding and nursery ponds of such a large area. Evidence has emerged that optimal size feeding ponds should be 8 + 2 hectares. With a smaller area, the share of dams increases and the land is used less efficiently. With more, the ponds become less manageable.

The area of nursery ponds has traditionally been smaller than feeding ponds. In general, with increasing intensification, there is a tendency to reduce the area of individual ponds. A typical example is China, a world leader in aquaculture, where 60% of all pond fish are grown by farmers in ponds smaller than 1 hectare. An argument in favor of reducing the size of ponds can be the well-known fact that the productivity of small reservoirs is always higher than that of large ones. This is explained by a larger share of the productive metoral (coastal) zone, where food organisms that serve as food for fish develop better.

"Small ponds, in terms of the profit they provide, are similar to small plots of land, which usually bring more income, than the equal spaces of a large estate. The water in such small ponds is almost always nutritious, and the fish in it grow very quickly, which is why small ponds always produce better income than larger ones. Anyone who has been involved in fish farming at least a little knows about this,” wrote the already mentioned Ferdinand Wilkosz. Everything said above should serve as confirmation of the thesis that in reality the area of ponds is difficult to ration, can vary greatly and everything depends on specific conditions. However, this cannot be said about the average, minimum and maximum depths. The given standards are close to optimal for growing carp - the main object of cultivation in Russia. Therefore, when constructing new ponds, they should be followed. For other farming objects, such as sturgeon and salmon, the standard depths are somewhat different. They will be given in the following chapters. So, summing up everything that has been said in this chapter, we will highlight the mandatory actions of the future farmer when building ponds and technological solutions that are most suitable for creating a small fish farm.

If possible, a dam blocking a river, stream, ravine or ravine should be built from homogeneous soil (loam).
It is mandatory to construct a bottom drainage outlet, which can be of a simplified type in the form of a pipe laid in the body of the dam at the level of the bottom of the head pond.
If a flood spillway is needed, then, if possible, it is made in the form of a pipe laid through the dam at the level of the normal retaining level in the head pond.
If construction of floodplain ponds is planned, then the head water intake is made tubular.
The main canal is installed in a excavation, and the excavated soil is used to build a dam.
Water outlets from the canal into the ponds are made tubular.
If the size of the ponds allows (area up to 1 hectare), then fish collection and drainage channels are not cut into the bed, and fish catchers are not made.
For the most effective use of constructed ponds, it is necessary to maintain regulatory depths.
The construction of bottom drains or, at least, siphon spillways is mandatory.
Pond dams, if possible, are made of loam.

The quality of water in a reservoir is assessed based on the results of chemical, bacteriological and biological analyses. Each of these types of analysis has its own advantages and disadvantages, they do not replace each other, and the most reliable assessment is obtained by combining all three methods.

Chemical research make it possible to assess the magnitude and nature of pollution, its impact on changes in water quality. Bacteriological analysis makes it possible to determine the likelihood of being in the water pathogenic microorganisms. Biological analysis helps to establish the degree of pollution of a reservoir as a whole, in some cases making it possible to record the consequences of short-term pollution of a reservoir, which cannot be recorded by methods of physicochemical and bacteriological research.

Biological analysis of water is based on the association of certain organisms with water of a certain quality.

In 1909, R. Kolkwitz and M. Marson developed a classification of the degree of pollution of water bodies according to the plant and animal species they contained. This classification, called the saprobity system, was later improved. In our country, in its most complete form, it was developed by Ya. Ya. Nikitinsky and G. I. Dolgov (1927). According to their definition, “saprobity is a complex of physiological properties of a given organism, which determines its ability to develop in water with one or another content.” organic matter, with varying degrees of contamination."

As a result of the self-purifying ability of reservoirs, the pollutants entering the reservoir are gradually diluted and destroyed. The destruction of pollution occurs gradually and, in connection with this, the conditions in the reservoir that were in it before the entry are gradually restored. Wastewater. This process is very long, and the pollution zone in the river can cover tens and hundreds of kilometers. The size of the zone depends on the ratio of the volume of wastewater and river water, on the concentration and quality of pollutants, on flow speed and other reasons.

Depending on how heavily polluted the water is, reservoirs and their individual areas are divided into the following zones:

When a reservoir is polluted, its physical and chemical conditions change. In this case, some forms of hydrobionts die, others receive advantages for their development, and as a result, a change in biocenosis occurs in the contaminated area. Many aquatic organisms are able to develop only in water of a certain quality and are therefore adapted to certain zones of pollution.

The polysaprobic zone (p) is characterized by a high content of unstable organic substances and products of their anaerobic decomposition. Protein substances are present in abundance in water. BOD is tens of milligrams per liter. There is no photosynthesis. Oxygen can enter water only through atmospheric resorption, and since it is completely consumed for oxidation in the surface layers, it is practically undetectable in water. The water contains methane and hydrogen sulfide. This zone is characterized a large number of saprophytic microflora, represented by hundreds of thousands and even millions of cells per 1 ml. There is no oxygen in bottom sediments, there is a lot of detritus, reduction processes are taking place, iron is in the form of FeS, the sludge has a black color and the smell of hydrogen sulfide. In this zone, plant organisms with a heterotrophic type of nutrition develop en masse: various bacteria, including filamentous bacteria (Sphaerotilus), sulfur bacteria (Beggiatoa, Thiothris), bacterial zoogloea (Zoogloea ramigera), ciliate protozoa, colorless flagellates (Fig. 62).

Alpha mesosaprobic zone (?-m). In this zone, aerobic decomposition of organic substances begins with the formation of ammonia, there is a lot of free carbon dioxide, oxygen is present in small quantities. Methane and hydrogen sulfide are absent. The amount of pollution measured by BOD is still very high: tens of milligrams per liter. The number of saprophytic bacteria is tens and hundreds of thousands per 1 ml.

Redox processes occur in water and bottom sediments; iron - in ferrous and oxide forms, grayish silt. In the?-m zone, organisms develop that have great tolerance to a lack of oxygen and a high carbon dioxide content. Plant organisms with heterotrophic and mixotrophic nutrition predominate. Individual organisms have a massive development: bacterial zooglea, filamentous bacteria, fungi, oscillatory algae, stigeoclonium. Among animal organisms, sessile ciliates (Carchesium) are abundant, rotifers (Brachionus), and many colored and colorless flagellates are found (Fig. 63). The sludge contains a significant amount of tubificides and chironomid larvae.

The beta-mesosaprobic zone (?-m) is observed in water bodies almost free of unstable organic substances that have decomposed to acidic products (complete mineralization). The number of saprophytic bacteria is thousands of cells per 1 ml and increases sharply during the period of death aquatic plants. The concentration of oxygen and carbon dioxide fluctuates greatly throughout the day; during the daytime, the oxygen content in the water reaches saturation, and carbon dioxide can completely disappear; at night, there is a deficiency of oxygen in the water. There is a lot of detritus in the silt, oxidative processes occur intensively, and the silt is yellow in color. This zone has a wide variety of animal and plant organisms. Plant organisms with autotrophic nutrition develop in the mass, and “blooming” of water is observed as a result of the development of phytoplankton. Green filaments and epiphytic diatoms are common in fouling; in silts - worms, chironomid larvae, mollusks (Fig. 64).

The oligosaprobic zone (o) characterizes practically clean water bodies with an insignificant content of unstable organic substances and a small amount of their mineralization products. The oxygen and carbon dioxide content does not undergo noticeable fluctuations during the day and night hours.

As a rule, water “blooming” is not observed. Bottom sediments contain little detritus, autotrophic microorganisms and benthic animals (worms, chironomid larvae and mollusks). Some red algae (Thorea, Batrachospermum) and aquatic mosses are indicators of the high purity of water in this zone (Fig. 65).

Individual indicator organisms taken in isolation cannot sufficiently accurately characterize the degree of water pollution. For example, when proteins decompose in household wastewater, sulfur accumulates; as a result, sulfur bacteria from the genera Beggiatoa and Thiothrix can be found in abundance in such waters. At the same time, these bacteria also live in the water of mineral sulfur springs, which do not contain any organic contaminants. Sulfur bacteria are indicators of sulfur in water, regardless of the origin of this sulfur.

The above example shows that the degree of water pollution can be judged only by cenoses characteristic of a particular zone of saprobity, and not by individual, even indicator, organisms.

Currently, many authors propose a more detailed division of saprobity zones, identifying 5, 6 or more subzones. Thus, Liebmann (1962) provides for 4 main classes of reservoir cleanliness (p. 194) and three intermediate ones. The main classes are designated by numbers from I (the purest, corresponding to the oligosaprobic zone) to IV (corresponding to the polysaprobic zone). Intermediate - two numbers: I-II, II-III, III-IV. A. A. Bylinkina, S. M. Drachev and A. I. Itskova proposed dividing reservoirs according to the degree of pollution into 6 groups: very clean, clean, moderately polluted, polluted, dirty and very dirty. Each of these gradations corresponds to a certain amount of pollution.

Very clean water bodies show virtually no traces of human impact. In the USSR, many lakes and rivers of Siberia can be classified as such reservoirs, and on European territory - Lakes Ladoga and Onega, the Rybinsk Reservoir, some northern rivers. In these reservoirs, water saturation with oxygen reaches 95%, MIC does not exceed 1 mg/l, and suspended substances do not exceed 3 mg/l. Water in very clean reservoirs is suitable for all types of water use.

Reservoirs classified as clean are almost no different in chemical indicators from very clean ones, but traces of human activity are manifested primarily in an increase in the amount of saprophytic microflora in the water. The waters of reservoirs of the second group are also suitable for all types of water use. Chlorination is sufficient to disinfect them.

Moderately polluted waters are characterized by a high content of organic substances, chlorine and ammonium ions. They bear signs of contamination by surface runoff and domestic water. Moderately polluted waters, after appropriate purification, are suitable for domestic and drinking use, for breeding certain types of fish and for other types of water use.

The polluted category includes rivers and lakes, natural properties which are significantly altered as a result of wastewater entering them. IN winter period when ice cover forms in contaminated areas of a reservoir, it can create anaerobic conditions. Polluted waters are unsuitable for drinking, domestic and cultural purposes, as well as for fish farming. They can be used, and even then with restrictions, in some production processes, for irrigation and shipping. In countries Western Europe in case of acute water shortage, contaminated water is used for household and drinking purposes, using complex ways cleaning,

In dirty and very dirty reservoirs, the natural properties of water are greatly altered. IN summer period The bottom of these reservoirs emits unpleasant odors. The increased content of aggressive carbon dioxide and sulfur compounds in the water of dirty reservoirs has a harmful effect on ship lining and port facilities, as a result of which these reservoirs are limitedly suitable for navigation. For irrigation, water from dirty reservoirs can be used with restrictions, not for all crops.

In table Table 3 shows some chemical indicators of the degree of pollution of water bodies.

When assessing the degree of contamination, organoleptic indicators are also taken into account, such as color, smell, turbidity, etc. For example, smell may indicate the presence of a number of undesirable impurities in water before they become available for chemical analysis. For this reason, many toxic substances are limited for entry into a body of water not because of their harmfulness, but because of their smell. Such substances include phenol, dichloroethane, cresols and other chemical compounds. The presence of oil in water is also limited by organoleptic indicators: by smell and visually, by the formation of films and stains on the surface of the water. Due to the fact that wastewater largely carries contaminants characteristic of industrial wastewater, including toxic substances, V.I. Zhadin (1964) proposed characterizing the pollution of water bodies not only by the degree of saprobity, but also by degree of toxicity, meaning by this term the ability of aquatic organisms to exist in waters containing a certain amount of toxic substances. By analogy with saprobic zones, he proposed to designate toxic zones as polytoxic, mesotoxic and oligotoxic.

Organization of pollution observation points surface waters

Most important stage The organization of work to monitor surface water pollution is the choice of the location of the observation point. This point is understood as a place on a reservoir in which a set of works is carried out to obtain data on water quality. Observation points are organized, first of all, on reservoirs that are of great economic importance, as well as those susceptible to pollution by wastewater from energy and industrial enterprises, household wastewater, as well as runoff from agricultural land and livestock complexes.

Before organizing points, preliminary surveys are carried out, which have the following purposes:

State Definition water body, collection and analysis of information about water users, identification of sources of pollution, quantity, composition and regime of wastewater discharges into a reservoir or watercourse;

Determination of the location of observation points, observation sites, verticals and horizons in them;

Establishment of characteristics for a given reservoir or watercourse of pollutants and biotopes;

Drawing up a work program.

Main water research programs

Based on research materials water bodies draw up a schematic map of a reservoir, watercourse or parts thereof, indicating sources of pollution and places of wastewater discharge. Then mark the location of observation points and sites. Then a survey of the reservoir or watercourse is carried out, during which sources of pollution are examined (location, nature, mode of wastewater discharge, their quantity and composition), and water samples are taken to determine hydrochemical and hydrobiological indicators in them in order to identify pollutants characteristic of a given point substances. Table 1 presents the main programs for studying water bodies.

There are other programs, for example, such as:

1) an observation program for hydrobiological indicators, according to which information is studied:

About phytoplankton - a collection of plant organisms inhabiting the water column;

Zooplankton - a collection of animals inhabiting the water column, passively transported by currents;

Zoobenthos - a collection of animals living at the bottom of sea and fresh water bodies;

Periphyton - a collection of organisms that settle on the underwater parts of river vessels, buoys, piles and other artificial structures;

2) quality observation programs sea waters(without hydrobiological indicators), shortened and complete.

Standardization and regulation of water quality in reservoirs

The protection of water bodies from pollution is carried out in accordance with the “Sanitary Rules and Standards for the Protection of Surface Waters from Pollution” (1988). Rules include General requirements to water users regarding the discharge of wastewater into water bodies. The rules establish two categories of reservoirs:

I- reservoirs for drinking and cultural purposes;

II - reservoirs for fishing purposes.

The composition and properties of water in water bodies of the first type must comply with the standards at sites located in watercourses at a distance of at least one kilometer above the nearest point of water use downstream, and in stagnant reservoirs - within a radius of at least one kilometer from the point of water use. The composition and properties of water in type II reservoirs must comply with the standards at the point of wastewater discharge with a dispersive outlet (in the presence of currents), and in the absence of a dispersive outlet - no further than 500 m from the outlet.

The rules establish standardized values for the following parameters of water in reservoirs: the content of floating impurities and suspended particles, smell, taste, color and temperature of water, pH value, composition and concentration of mineral impurities and oxygen dissolved in water, biological need of water for oxygen, composition and maximum permissible concentration (MPC) of toxic and harmful substances and pathogenic bacteria. Maximum permissible concentration - the concentration of a harmful (toxic) substance in the water of a reservoir, which, with daily exposure for a long time on the human body, does not cause any pathological changes and diseases, including in subsequent generations, detected modern methods research and diagnostics, and does not violate the biological optimum in the reservoir.

Harmful and toxic substances are varied in their composition, and therefore they are standardized according to the principle of the limiting hazard index (LHI), which is understood as the most likely adverse effect of a given substance. For reservoirs of the first type, three types of LPW are used: sanitary-toxicological, general sanitary and organoleptic; for reservoirs of the second type, two additional types are used: toxicological and fishery.

The sanitary condition of the reservoir meets the requirements of the standards when fulfilling the inequality

for each of the three (for reservoirs of the second type - for each of five) groups of harmful substances, the maximum permissible concentrations of which are established respectively according to the sanitary-toxicological LP, general sanitary LP, organoleptic LP, and for fishery reservoirs - also according to the toxicological LP and fishery LP. Here n is the number of harmful substances in a reservoir, belonging, for example, to the “sanitary-toxicological” group of harmful substances; C, is the concentration of the z-th substance from a given group of harmful substances; t - number of the group of harmful substances, for example, t = 1 - for the “sanitary-toxicological” group of harmful substances, t = 2 - for the “general sanitary” group of harmful substances, etc. - a total of five groups. This should take into account
background concentrations of harmful substances contained in the water of a reservoir before the discharge of wastewater. If one harmful substance with concentration C predominates in the group of harmful substances of a given LP, the requirement C + Sf must be satisfied<ПДК.

MPCs have been established for more than 400 harmful basic substances in water bodies for drinking and cultural purposes, as well as more than 100 harmful basic substances in water bodies for fishing purposes. In table Table 2 shows the maximum permissible concentrations of some substances in the water of reservoirs.

table 2

Maximum permissible concentrations of certain harmful substances in water bodies

Substance	Reservoirs of category I		Reservoirs of category II
Substance	LPV	Maximum permissible concentration, g/m 3	LPV	Maximum permissible concentration, g/m 3
Benzene	Sanitary T toxicological	0,5	Toxicological	0,5
Phenols	Organoleptic	0,001	Fishery	0,001
Gasoline, kerosene	Same	0,1	Same	0,05
Сd 2+	Sanitary toxicological	0,01	Toxicological	0,005
Cu 2+	Organoleptic	1	Same	0,01
Zn2+	General sanitary	1	Same	0,01
Cyanide	Sanitary toxicological	0,1	Same	0,05
Cr6+	Organoleptic	od	Same	0

For wastewater itself, maximum permissible concentrations are not standardized, but maximum permissible quantities of discharge of harmful impurities (MPD) are determined. Therefore, the minimum required degree of wastewater treatment before discharging it into a reservoir is determined by the condition of the reservoir, namely, the background concentrations of harmful substances in the reservoir, the water flow of the reservoir, etc., i.e., the ability of the reservoir to dilute harmful impurities.

It is prohibited to discharge wastewater into reservoirs if it is possible to use more rational technology, waterless processes and systems of repeated and recycled water supply - repeated or constant (multiple) use of the same water in the technological process; if the effluent contains valuable waste that can be disposed of; if the wastewater contains raw materials, reagents and production products in quantities exceeding technological losses; if the wastewater contains substances for which MPCs have not been established.

The reset mode can be one-time, periodic, continuous, variable flow, random. It is necessary to take into account that the water flow in the reservoir (river flow) varies both by season and by year. In any case, the requirement of condition (17a) must be satisfied.

The method of wastewater discharge is of great importance. With concentrated discharges, the mixing of wastewater with the water of the reservoir is minimal, and the polluted stream can have a long extension in the reservoir. The most effective use of dissipative outlets in the depths (at the bottom) of the reservoir in the form of perforated pipes.

One of the tasks of regulating the quality of water in reservoirs is to determine the permissible composition of wastewater, i.e., the maximum content of a harmful substance (substances) in the effluent, which, after discharge, does not cause the concentration of a harmful substance in the waters of a reservoir to exceed the maximum permissible concentration of this harmful substance.

Forecasting and monitoring the condition of reservoirs

Forecasting the state of reservoirs or other natural systems is based on the study and analysis of the patterns of their development, variability under the influence of anthropogenic and other factors. It is based on standards that determine permissible limits for emissions of harmful substances and the value of their maximum permissible concentrations. In our country, maximum permissible discharge standards (MPD) are used, established for each enterprise in such a way that the total water pollution from all sources in a given area is within the MPC.

The forecast of water pollution, depending on the objectives, duration and forecasting methods, is divided into two parts:

General forecast assessment of changes in the hydrochemical regime and the degree of pollution under the influence of all anthropological factors in the catchment area;

Forecast of water pollution due to the influence of one or more factors.

General forecast assessments of water pollution are made by analyzing and identifying trends in changes in water flow and the chemical composition of water over many years. Studying the features of regime formation in the background area and in the zone of anthropogenic influence, as well as studying the same reservoir at different times, makes it possible to identify anthropogenic changes and predict possible transformations of the hydrochemical regime.

To predict the impact of discharges from chemical enterprises on the composition of river water, methods are used that take into account the dilution of waste and river waters. The average concentration of the pollutant (C, mg/dm2) is determined by the formula

where SF is the average concentration of pollutant in the background section of the river;

G; - the total amount of pollutants entering the river with wastewater from the 1st enterprise, g;

Wf - water flow in the background section of the river, m 3;

Уi; - coefficient of displacement of waste and river waters;

k is the rate coefficient for self-purification of river water from pollutants, day"1;

T is the time it takes water to travel from the 1st source to the target, days.

Issues of changes in river landscapes are not considered here. However, it should be pointed out that under the conditions of technogenesis, their transformation is significantly expanded due to the entry into the river of wastewater with a high content of organic substances and elements unusual for it. In particular, the concentration of dissolved oxygen in water decreases, and a reducing hydrogen sulfide environment appears in sediments.

Normal operation of water supply and sewerage facilities is impossible without monitoring the quality parameters of natural and waste water at different stages of their purification, supply to consumers and release into water bodies. For this purpose, analytical technology and automatic instruments are widely used in the form of signaling the limit values of measured quantities or by recording them.

The most important component of water and sanitary legislation is the maximum permissible concentrations of harmful substances in the water of reservoirs. At the same time, a distinction is made between maximum permissible concentrations for water bodies for domestic, drinking, cultural and domestic use and maximum permissible concentrations for fishery purposes.

When establishing the maximum permissible concentration of a substance, three signs of harmfulness are considered: general sanitary, organoleptic and sanitary-toxicological. General sanitary hazard refers to the influence of harmful substances in wastewater on the sanitary regime of water bodies, that is, the processes of their natural self-purification from organic pollution, primarily from domestic waters. Under the influence of industrial wastewater, the self-purification processes of water bodies are often disrupted due to, for example, disruption of the oxygen regime due to a significant discharge of easily oxidized and fermentable compounds into the water. With a significant decrease in the oxygen content in water, the formation of films and solid contaminants floating on the surface, the appearance of fungal formations and other signs of the development of putrefactive processes occur. Such a body of water becomes unsuitable for swimming and other cultural and everyday purposes.

Harmful substances in wastewater affect the organoleptic properties and quality of water. Thus, the presence of a film of mineral oils on the surface of the water, an unpleasant odor and taste, unusual coloring, elevated temperature and water hardness limit the use of reservoirs for cultural, domestic and sports purposes.

The sanitary and toxicological hazards of wastewater are associated with the influence of the harmful substances contained in them on the health of the population - sources of drinking water supply. The establishment of maximum permissible concentrations here is based on subthreshold concentrations of substances, that is, concentrations at which no noticeable change in the functional state of the body is observed. This also takes into account the possibility of long-term effects of pollutants on humans - mutagenic (changes in heredity), gonadotropic (sexual dysfunction), embryotropic (impaired development of the year) and blastomagenic (tumor) effects.

The maximum permissible concentration of a substance is usually established according to the sign of harmful effects that corresponds to - (a lower indicator of the threshold or subthreshold concentration. Since it determines the nature of the adverse effect of lower concentrations of the substance, this sign is called the citing sign of harmfulness. Determining the maximum permissible concentration by the threshold subthreshold concentration of the limiting sign creates a reserve reliability for the other two signs of harmfulness.

As a rule, water bodies are simultaneously polluted by several substances. The effect of harmful compounds with the same limiting characteristics is summed up. To date, the Cassia has approved over 600 maximum permissible concentrations for harmful substances in public water bodies. Fishery MPCs established for 137 compounds are the concentrations of pollutants, the constant presence of which in a reservoir fulfills the following conditions:

There are no cases of death of fish and organisms serving! food for them;

There is no extinction of species that rely on the reservoir for their life | suitable, as well as replacing organisms that are valuable for food with low-value ones;

There is no deterioration of the commercial qualities of the fish, no unpleasant tastes and odors appear;

There are no changes that could lead in the future to the death of fish, the replacement of their valuable species with low-value ones, or the loss of the fishery value of the reservoir.

Industrial and domestic wastewater usually contains a large number of organic and inorganic pollutants of various compositions, which, as a rule, are oxidized and decomposed using oxygen. The general level of pollution is characterized by the amount of oxygen demand, which is divided into biochemical and chemical.

Biochemical oxygen demand (BOD) refers to the amount of oxygen (mg/l) that is required by living organisms to oxidize organic and inorganic substances contained in 1 liter of wastewater. Biochemically oxidized, only those components that can be used by organisms for their life are exposed.

BOD values are always indicated with an index indicating the duration of oxidation in days. In this case, BOD10 is always higher than BOD5 due to deeper oxidation. Hence, the value of the biological demand for oxygen will tend to a certain piece value, designated as BODn (total). Its value for food is economic - in drinking and fishing water bodies, the oxygen level at 20°C should not exceed 3 mg O2/l.

Chemical oxygen demand (COD) refers to the amount of oxygen (mg/l) in wastewater that is required to oxidize organic and inorganic compounds found in water. When determining COD, a hot solution of potassium dichromate is usually used as an oxidizing agent. The COD value is the most important characteristic of industrial wastewater. COD is always greater than BODp due to deeper oxidation by chemical means compared to biochemical. The COD value varies from 10-20 mg[-l for relatively clean water to 1000 mg O2/l or more for heavily polluted water. The ratio of BPK/COD values is called a biochemical indicator, the value of which is always less than one. Its value is used to judge the possibility and degree of biological wastewater treatment. Thus, household wastewater, which is more completely purified by biological means, is characterized by an indicator of 0.5. The value of the biochemical indicator for wastewater varies between 0.05-0.30.

To control the quality parameters of water, devices for general industrial purposes are used. These include various designs of density meters, salinity meters, pH meters, photocolorimeters, concentration meters, hygrometers, and polarographs. In addition, instruments are used that are designed specifically for analyzing indicators of water supply and sewerage facilities, such as COD, BOD, and dissolved oxygen.

10.1 Standardization and regulation of water quality in reservoirs

The protection of water bodies from pollution is carried out in accordance with the “Sanitary Rules and Standards for the Protection of Surface Waters from Pollution” (1988). The rules include general requirements for water users regarding the discharge of wastewater into water bodies. The rules establish two categories of reservoirs: 1 – reservoirs for drinking and cultural purposes; 2 – reservoirs for fishing purposes. The composition and properties of water in water bodies of the first type must comply with the standards at sites located in watercourses at a distance of at least one kilometer above the nearest water use point downstream, and in stagnant reservoirs - within a radius of at least one kilometer from the water use point. The composition and properties of water in type II reservoirs must comply with the standards at the point of wastewater discharge with a dispersive outlet (in the presence of currents), and in the absence of a dispersive outlet - no further than 500 m from the outlet.

The rules establish standardized values for the following parameters of water in reservoirs: the content of floating impurities and suspended particles, smell, taste, color and temperature of water, pH value, composition and concentration of mineral impurities and oxygen dissolved in water, biological need of water for oxygen, composition and maximum permissible concentration (MPC) of toxic and harmful substances and pathogenic bacteria. The maximum permissible concentration is understood as the concentration of a harmful (toxic) substance in the water of a reservoir, which, when exposed to the human body daily for a long time, does not cause any pathological changes and diseases, including in subsequent generations, detected by modern research and diagnostic methods, and also does not violate the biological optimum in the reservoir.

Harmful and toxic substances are diverse in their composition, and therefore they are standardized according to the principle of the limiting hazard index (LHI), which is understood as the most likely adverse effect of a given substance. For reservoirs of the first type, three types of LPW are used: sanitary-toxicological, general sanitary and organoleptic; for reservoirs of the second type, two more types are used: toxicological and fishery.

The sanitary condition of the reservoir meets the requirements of the standards when fulfilling the inequality

C i

n ∑ i=1

MPC i

for each of the three (for reservoirs of the second type - for each of the five) groups of harmful substances, the maximum permissible concentrations of which are established respectively according to the sanitary-toxicological LP, general sanitary LP, organoleptic LP, and for fishery reservoirs - also according to the toxicological LP and fishery LP . Here n is the number of harmful substances in the reservoir, which, let’s say, belong to the “sanitary-toxicological” group of harmful substances; C i – concentration of the i-th substance from a given group of harmful substances; m – number of the group of harmful substances, for example, m = 1 – for the “sanitary-toxicological” group of harmful substances, m = 2 – for the “general sanitary” group of harmful substances, etc. – only five groups. In this case, the background concentrations C f of harmful substances contained in the water of the reservoir before the discharge of wastewater must be taken into account. If one harmful substance with concentration C predominates in the group of harmful substances of a given drug, the following requirement must be met:

C + C f ≤ MPC, (10.2)

Maximum permissible concentrations have been established for more than 640 harmful basic substances in water bodies for drinking, cultural and domestic purposes, as well as more than 150 harmful basic substances in water bodies for fishing purposes. Table 10.1 shows the maximum permissible concentrations of some substances in the water of reservoirs.

For wastewater itself, MPCs are not standardized, but rather maximum permissible amounts of discharge of harmful impurities, MAC, are determined. Therefore, the minimum required degree of wastewater treatment before discharging it into a reservoir is determined by the condition of the reservoir, namely, the background concentrations of harmful substances in the reservoir, the water flow of the reservoir, etc., that is, the ability of the reservoir to dilute harmful impurities.

The reset mode can be one-time, periodic, continuous with variable flow, random. It is necessary to take into account that the water flow in the reservoir (river discharge) varies both by season and by year. In any case, the requirements of condition (10.2) must be satisfied.

Table 10.1

Maximum permissible concentrations of certain harmful substances in water

yomah

Sanitary

toxicological

Organoleptic

Sanitary

toxicological

Organoleptic

General sanitary

Sanitary

toxicological

Organoleptic

In accordance with the above, one of the tasks of regulating the quality of water in reservoirs is the task of determining the permissible composition of wastewater, that is, the maximum content of a harmful substance (substances) in the effluent, which, after discharge, will not result in an excess of the concentration of a harmful substance in the waters of a reservoir above the maximum permissible concentration of this harmful substance substances.

The equation for the balance of a dissolved impurity when discharging it into a watercourse (river), taking into account the initial dilution at the outlet site, has the form:

C st = n o (10.3)

Here C cm, C r.s, C f are the concentrations of impurities in wastewater before release into the reservoir, at the design site and the background concentration of impurities, respectively, mg/kg; n o and n р.с – dilution ratio of wastewater at the outlet site (initial dilution) and at the design site, respectively.

Initial dilution of wastewater at its discharge point

where Q o = LHV – part of the drainage flow flowing over the dissipative outlet, which, let’s say, has the form of a perforated pipe laid on the bottom, m 3 /s; q – wastewater flow, m 3 /s; L – length of the dissipative outlet (perforated pipe), m; H, V – average depth and flow velocity above the outlet, m and m/s.

After substituting (10.4) into (10.3) we obtain that

At LHV >> q

As the drainage flows, the stream of wastewater expands (due to diffusion, turbulent and molecular), as a result of which in the stream the wastewater is mixed with the water of the stream, the dilution factor of the harmful impurity increases and its concentration in the stream of wastewater, or rather, now mixed water, constantly decreases. Ultimately, the alignment (cross section) of the jet will expand to the alignment of the watercourse. At this point in the watercourse (where the point of the polluted stream coincides with the point of the watercourse), the maximum possible dilution of the harmful impurity for a given watercourse is achieved. Depending on the magnitude of the initial dilution factor, width, speed, tortuosity and other characteristics of the watercourse, the concentration of a harmful impurity (C p.c.) can reach the value of its maximum permissible concentration in different sections of the polluted stream. The sooner this happens, the smaller the area (volume) of the watercourse will be contaminated with harmful impurities above the norm (above the MPC). It is clear that the most suitable option is when condition (10.2) is satisfied at the very point of release and, thus, the size of the polluted section of the watercourse will be reduced to zero. Let us recall that this option corresponds to the condition of releasing wastewater into a watercourse of the second type. Regulatory dilution to the maximum permissible concentration at the discharge site is also required for watercourses of the first type, if the discharge is carried out within the boundaries of a populated area. This option can be achieved by increasing the length of the perforated exhaust pipe. In the limit, blocking the entire drain with an outlet pipe and thus including the entire flow of the watercourse in the process of diluting the wastewater, taking into account that for the outlet site n р.с = 1, and also putting in (10.5) C = MPC , we get:

(10.7)

where B and H are the effective width and depth of the watercourse; accordingly, Q = BHV is the water flow of the stream.

Equation (10.7) means that with maximum use of the dilution capacity of the watercourse (watercourse flow), the maximum possible concentration of a harmful substance in the discharged wastewater can be allowed to be equal to

and in the second should be considered as extremely

permissible discharge (PDS) of a given hazard into a watercourse, g/s. If these MPC values are exceeded (Q MPC and 0.2Q MPC, g/s), the concentration of the harmful substance in the waters of the stream will exceed the MPC. In the first case (MPD = Q MPC), turbulent (and molecular) diffusion will no longer reduce the concentration of harmfulness along the watercourse, since the initial dilution site coincides with the site of the entire watercourse - the stream of polluted water has nowhere to diffuse. In the second case, along the watercourse there will be a dilution of the effluent and a decrease in the concentration of harmful substances in the water of the reservoir, and at some distance S from the outlet the concentration of the harmful substance may decrease to the maximum permissible concentration and below. But even in this case, a certain section of the watercourse will be polluted above the norm, that is, above the MPC.

In the general case, the distance from the outlet point to the design point, that is, to the point with a given dilution factor, n r.s. or - which is actually the same thing - with a given concentration of a harmful impurity, for example, equal to its MPC will be equal

where A = 0.9...2.0 – proportionality coefficient, depending on the category of the channel and the average annual water flow of the stream; В – width of the watercourse, m; x is the width of the part of the channel in which the outlet is not produced (the pipe does not cover the entire width of the channel), m; f- channel tortuosity coefficient: the ratio of the distance between the sections along the fairway to the distance in a straight line; Re = V H / D – Reynolds diffusion criterion.

The expansion of the polluted jet along the watercourse occurs mainly due to turbulent diffusion, its coefficient

where g is the acceleration of gravity, m 2 /s; M is a function of the Chezy coefficient for water. M=22.3 m 0.5 /s; S w – Chezy coefficient, S w = 40...44 m 0.5 / s.

After potentiation (10.8) the value n р.с is obtained in explicit form

Equation (10.11) means: if at the initial dilution determined by the values of L, H, V, and with known characteristics of the watercourse j, A, B, x, R ∂, C f it is necessary that at a distance S from the wastewater outlet the concentration of the harmful substance is at the level of maximum permissible concentration and less, then the concentration of harmful substances in the wastewater before discharge should not exceed the value C cm calculated by (10.11). Multiplying both parts of (10.11) by the value q, we arrive at the same condition, but through the maximum permissible reset C cm q = MDS:

From the general solution (10.12) follows the same result that was obtained above based on simple considerations. In fact, let us assume that the problem is being solved: what can be the maximum (maximum permissible) discharge of wastewater into a watercourse, so that already at the point of release (S = 0) the concentration of a harmful substance is equal to the maximum permissible concentration, and for the initial dilution only a fifth of the flow rate is used watercourse (river discharge), that is, LHV = 0.2 Q.

Since at S = 0 n р.с = 1, from (10.12) we obtain:

MPC = 0.2 MPC.

In general, the regulation of water quality in watercourses when discharging suspended, organic substances into them, as well as water heated in the cooling systems of enterprises, is based on the principles outlined.

The conditions for mixing wastewater with water from lakes and reservoirs differ significantly from the conditions for their mixing in watercourses - rivers and canals. In particular, complete mixing of wastewater and waters of a reservoir is achieved at significantly greater distances from the point of release than in watercourses. Methods for calculating the dilution of runoff in reservoirs and lakes are given in the monograph by N.N. Lapsheva Calculations of wastewater discharges. – M.: Stroyizdat, 1977. – 223 p.

10.2 Methods and instruments for monitoring water quality in reservoirs

Water quality control of reservoirs is carried out by periodic selection and analysis of water samples from surface reservoirs: at least once a month. The number of samples and the location of their collection are determined in accordance with the hydrological and sanitary characteristics of the reservoir. In this case, it is mandatory to take samples directly at the point of water intake and at a distance of 1 km upstream for rivers and canals; for lakes and reservoirs - at a distance of 1 km from the water intake at two diametrically located points. Along with the analysis of water samples, laboratories use automatic water quality monitoring stations, which can simultaneously measure up to 10 or more water quality indicators. Thus, domestic mobile automatic water quality control stations measure the concentration of oxygen dissolved in water (up to 0.025 kg/m 3), electrical conductivity of water (from 10-4 to 10-2 Ohm/cm), pH value (from 4 to 10), temperature (from 0 to 40°C), water level (from 0 to 12m). Suspended solids content (from 0 to 2 kg/m3). Table 10.2 shows the quality characteristics of some domestic standard systems for monitoring the quality of surface and waste water.

At treatment facilities of enterprises, they monitor the composition of source and treated wastewater, as well as monitor the efficiency of treatment facilities. Control is usually carried out once every 10 days.

Wastewater samples are collected in clean borosilicate glass or polyethylene containers. The analysis is carried out no later than 12 hours after sampling. For wastewater, organoleptic indicators, pH, suspended solids content, chemical oxygen demand (COD), the amount of oxygen dissolved in water, biochemical oxygen demand (BOD), concentrations of harmful substances, for which there are standardized MPC values, are measured.

Table 10.2

Qualitative characteristics of some domestic standard systems for monitoring the quality of surface and waste waters

Application area

Physico-chemical analysis of composition and

properties of natural and waste waters

Determination of drinking water quality,

water of reservoirs, composition of wastewater and

Automatic detection and recording

physical and chemical parameters of the surface

local waters, including concentrations

Cl 2, F 2, Cu, Ca, Na, phosphates, nitrides

Two organoleptic indicators of water are monitored when analyzing wastewater: odor and color, which is established by measuring the optical density of the sample on a spectrophotometer at different wavelengths of transmitted light.

The pH value in wastewater is determined electrometrically. It is based on the fact that when measuring pH in a liquid, the potential of a glass electrode immersed in the liquid changes by a constant value for a given temperature (for example, by 59.1 mV at a temperature of 298 K, by 58.1 mV at 293 K, etc.). d.). Domestic brands of pH meters: KP-5, MT-58, LPU-01, etc.

When determining coarse impurities in wastewater, the mass concentration of mechanical impurities and the fractional composition of particles are measured. For this purpose, special filter elements and measurement of the mass of “dry” sediment are used. Also, the rates of floating (sedimentation) of mechanical impurities are periodically determined, which is important when debugging treatment facilities.

The COD value characterizes the content of reducing agents in water that react with strong oxidizing agents and is expressed by the amount of oxygen necessary to oxidize all reducing agents contained in water. The wastewater sample is oxidized with a solution of potassium dichromate in sulfuric acid. The actual measurement of COD is carried out either by arbitration methods, carried out with great accuracy over a long period of time, and by accelerated methods used for daily analyzes in order to monitor the operation of treatment facilities or the state of water in a reservoir at a stable flow rate and composition of water.

Dissolved oxygen concentration is measured after wastewater is treated before being discharged into a body of water. This is necessary to assess the corrosive properties of wastewater and to determine the BOD. The Winkler iodometric method is most often used to detect dissolved oxygen concentrations greater than 0.0002 kg/m 3; lower concentrations are measured by colorimetric methods based on changes in the color intensity of compounds formed as a result of the reaction between special dyes and wastewater. To automatically measure the concentration of dissolved oxygen, use devices EG - 152 - 003 with measurement limits of 0 ... 0.1 kg/m 3, "Oximeter" with measurement limits of 0 ... 0.01 and 0.01 ... 0, 02 kg/m 3 .

BOD is the amount of oxygen (in milligrams) required for oxidation under aerobic conditions, as a result of biological processes occurring in water, of organic substances contained in 1 liter of wastewater, determined by the results of an analysis of changes in the amount of dissolved oxygen over time at 20°C. The most commonly used is the five-day biochemical oxygen consumption - BOD 5.

Measurement of the concentration of harmful substances for which maximum permissible concentrations are established is carried out at various stages of purification, including before releasing water into the reservoir.

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Why are fishery water quality standards needed? Water quality standards for water bodies of fishery importance. Classification, purpose and features of fishery reservoirs. Water quality standards for similar water bodies. Maximum concentration limits for some hazardous substances. Principles for calculating water standards for fishery water use objects. Fishery water quality standards help maintain the proper condition of reservoirs intended for growing fish. Water quality standards for water bodies of fishery importance are specified in orders of the Federal Fisheries Agency.

Classification of reservoirs of fishery importance

According to the regulatory document “Rules for the Protection of Surface Waters,” all surface water bodies are conventionally divided into the following categories:

facilities for household, drinking and cultural purposes;
fishery facilities.

We will consider the requirements for the latter type of water bodies in our article. Reservoirs for fishery water use are divided into certain subtypes:

Reservoirs of the first category are objects that are intended for breeding and preserving valuable species of fish. Such reservoirs are used for representatives of aquatic fauna, which are very demanding on the concentration of oxygen in the aquatic environment.
Reservoirs of the second category are fishery facilities that are used for other purposes.

If wastewater is discharged into such water bodies, then the quality of the aquatic environment in the reservoir must be assessed at a place located below the point of entry of the wastewater. These indicators must meet the requirements of sanitary standards for each type of water use.

Fishery water quality standards

The water quality standards for fishery facilities include the following indicators:

General characteristics of the components and qualities of the aquatic environment. Each type of water use facility has its own standards.
List of maximum permissible concentrations of substances present in the aquatic environment. MPCs for each substance may differ for each water use facility.

Despite the fact that the requirements for the concentration of certain substances differ for each water use facility, there are also general standards describing the composition and quality of the aquatic environment. These include: concentration of impurities, percentage of suspended solids, color, taste, smell, acidity, degree of mineralization, oxygen concentration, toxicity.

Maximum permissible concentrations of certain substances describe the permitted content of this substance in the aquatic environment, at which the water will be absolutely safe for inhabitants. In this case, the norm can be considered either the complete absence of a substance or its concentration lower than or equal to the agreed norm.

It is very important to regulate the concentrations of toxic substances, since some of them can slow down the natural processes of self-purification of a reservoir, namely the biochemical oxidation of organic matter. All this can lead to a poor state of the aquatic environment: lack of oxygen, rotting processes, and increased concentrations of hydrogen sulfide. That is why the maximum permissible concentrations of substances are standardized according to the general sanitary sign of harmfulness.

Water quality standards for water bodies of fishery importance normalize the concentration of hazardous substances:

Petroleum products. When their concentration in a reservoir is within the range of 0.1-0.2 mg/l, the fish acquires a specific smell and taste of petroleum products.
The concentration of substances hazardous to health is standardized based on toxicological characteristics.
A concentration of Cu ions of 10 mg/l can have a toxic effect on the body. The same substance in a volume of 5 mg/l can disrupt the self-purification processes of a reservoir, and the content of this substance in a volume of 1 mg/l impairs the taste of the liquid. As a result, for fishery reservoirs this indicator is standardized based on toxicological characteristics and is allowed to be no more than 10 mg/l.
Also in regulatory documents such an indicator as LPV is used - a limiting sign of harmfulness. It indicates the lowest maximum permissible concentration of a substance.
The concentration of arsenic in fishery reservoirs is 0.05 mg/l. And if you believe European standards, the concentration of this substance can be within 0.2 mg/l.

Principles for calculating water standards for fishery water use facilities

The principle of the “zero strategy” states that the slightest change in the natural aquatic environment must be considered unacceptable.
Any standards must be established in accordance with technological capabilities aimed at reducing the degree of pollution of the reservoir, as well as in accordance with the control of their concentration in the aquatic environment.
The maximum permissible concentration of pollutants must be normalized so that the costs of maintaining their normal concentration do not exceed the costs in the event of uncontrolled pollution of the reservoir.

If you need to perform an analysis of the aquatic environment of a reservoir to assess the concentration of various substances, you can order such a test in our laboratory. To do this, you just need to call the indicated numbers.

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