WO2008098322A1

WO2008098322A1 - Method for biological cleaning of water from reservoirs

Info

Publication number: WO2008098322A1
Application number: PCT/BG2008/000002
Authority: WO
Inventors: Evlogy Notev; Hristina Vaseva
Original assignee: Evlogy Notev; Hristina Vaseva
Priority date: 2007-02-16
Filing date: 2008-02-13
Publication date: 2008-08-21

Abstract

The invention applies to a method for biological cleaning of water and will be used in ecology, more specifically for the restoration of the disturbed balance of the ichthyo fauna and flora in the reservoirs and for minimizing the level of pollution of the water. The method concerning the invention includes operations for removal of part of the flora and fauna present in the reservoirs, followed by the formation of a Biological filter, consisting of different types of aquaplants, depositing the Biological filter in the reservoir with density of culture from 150 to 600 pieces of aquaplants per da and a periodical observation, control and corrections of the Biological filter.

Description

METHOD FOR BIOLOGICAL CLEANING OF WATER FROM RESERVOIRS

Technical Field

The invention applies to a method for biological cleaning of water and will be used in ecology, more specifically for the restoration of the disturbed balance of the ichthyo fauna and flora in the natural and artificial water reservoirs - lakes, artificial lakes, canals and other, for the purpose of cleaning the water from biological pollutants.

Background Art

The ichthyo fauna formation is a complicated process, concerning the specific negative conditions for natural and artificial closed water reservoirs and if left on its own in most cases it leads to deterioration of the quality of the water in the reservoirs due to accumulation of biological pollutants and due to their inability to release themselves.

There exist some water cleaning methods, consisting in the bringing in of certain fish species, thus influencing the food-chain ecosystem and respectively the cleanliness of the water indirectly "bottom-up". This is realised by means of bringing in the reservoir fish of prey such as European sheat fish, Perch, Perch pike, Trout and other. One of the enemies of phytoplankton, the main biological water pollutant, is zooplankton. The quantity of the latter can be increased by means of extermination of the "weed-like" fish (fish of little importance), which predominantly feeds on zooplankton. However this process is a slow one and should rather be used for maintenance of already clean water.

Another well-known method is the so called "top-down" method consisting in bringing in of fish that feeds on plankton - bighead carp, paddlefish and other species. This method also has its shortcomings because when it is applied independently, the quantity of "weed- like" fish increases and it turns into a pollutant just like phytoplankton and it on its side exterminates the zooplankton.

There is a method for biological rehabilitation of urban water reservoirs (RU 2 290 792), which recovers mainly the fauna in the reservoir, cleaning it by means of stable environment formation. The method consists in selection of the objects, preparation and population of hydrobionts (the combination of all water inhabitants). The selection of hydrobionts is made having in mind the biological peculiarities of the species and their compatibility. The preparation is made on a daily basis, where in the course of 10 to 30 days the hydrobionts are kept in a solution of a biologically active preparation with concentration 0.1 - 10 ml/1, with duration of the exposition from 30 up to 60 minutes and feeding them with food, combined with a biologically active preparation with quantity from 1 up to 50 ml/kg. Mineral water with total mineralization 2 — 4 g/dm³' containing: Calcium Cations from 30 up to 150 mg/ dm³; Magnezium - from 390 up to 450 mg/ dm³; Potassium - from 50 up to 70 mg/ dm³; Sodium - from 10200 up to 5320 mg/dm³; Iron - from 11 up to 57 mg/dm³; Selenium - < 1 mg/dm³; Copper - from 1 up to 3 mg/dm³ and Sulphite Ions - < 50 mg/dm³ is used as a biologically active preparation.

This method is labour-intensive, applicable only in urban water reservoirs, with a long process of realization and quite costly, having in mind the necessity for a preliminary processing of the biologically active preparation and the duration of the processing of the separate hydrobionts in it.

Disclosure of the invention

The improvement of the condition of the water and its bringing into a state almost suitable for use while already in the lake reservoir itself is most easily achieved in a natural way. The biological cleaning from biogen elements and vegetal pollutants and/or toxins is the most important task for all regions in the world. Most of the closed water reservoirs such as natural and artificial lakes, whose wall serves as a barrier for the natural migration and development of the living organisms, present a closed environment. The natural self- reproduction and the biological balance of the species, living in the water reservoirs of these closed environments, are disastrously disrupted in the course of time. One of the characteristic peculiarities of these reservoirs is the instability of the water level during the different periods of the year. The fluctuation of the water, the green-house effect and the climate anomalies in nature during the periods of spawning, have considerable negative influence. The droughts and floods resulting from these phenomena place the species, living in the reservoirs, under extreme conditions. Considerably influenced in this respect are the economically valuable aquacultures, which are useful not only for feeding the population of the planet Earth, but also for preserving the cleanliness of the drinking water, of the agricultural and industrial water. For most of the phytophile fish, which spawns on the soft coastal vegetation, the conditions are significantly worsened, due to the floods during the spawning period in spring and early summer. The vegetation dies as a result of floods and of silt covering. The high degree of muddiness of the water and the gravel, sand and mud deposits also limit the development of the organisms, living in the water reservoirs. Due to the summer heats and the eventual droughts, most of the benthic organisms cannot leave the dried out areas and die without producing offspring. The rheophile fish species are forced to leave the lake bed, while the limnophile ones are concentrated in the water reservoir itself.

For the less demanding "weed-like" fish species - rudd, goldfish, carassius , carp and other, the presented conditions remain favourable and as a result their number increases and the composition of the ichtyo fauna changes considerably. The quantity of the fish of no importance increases, while the number of economically valuable species, which are important for the biological balance and for the cleanliness of the water in the reservoirs, decreases to single pieces. Different levels of plankton duckweed development - phytoplankton such as: diatome, green, blue-green and other and zooplankton - Daphnia, Moina, Bosmina, Alona and other, which are the main pollutants of the water reservoirs, could be pointed out, depending on the quantity of the biological elements. Phytoplankton increases considerably in quantity, causes "flowering" and deprives the oxygen, dissolved in the water, while zooplankton not only enriches with new forms but also its quantity increases. All these factors, together with the uncontrolled spreading in the reservoirs of "weed-like" species of no importance, clams ("weed-like" clam dreissena), superior and inferior water plants as well as the lack of natural enemy, makes the water in the reservoirs dirty and unfit for use and for consumption.

The purpose of the invention is to create a method for biological cleaning of the water in natural and/or in artificial reservoirs (lakes, artificial lakes, canals, used in agriculture and industry) from biogen elements - "weed-like" fish, "weed-like" clams, harmful forms of zoo- and phytoplankton, superior plants, inferior plants and benthos changes, from organic loading of the biological environment by means of recovering the fauna and the flora of the water reservoir and formation of stable ecological system. The problem is solved with the help of the method, concerning the invention, which consists in the execution of a given sequence of operations, aiming at direct influence on the food-chain and at cleaning the water by means of selected aquaculture species, living in the water reservoirs and self-regulating the cleanliness of the water.

According the invention, before the method is applied, an evaluation and analysis of the condition of the water reservoir with regard to its degree of pollution should be made.

The water reservoirs which have a bio-environment, loaded with bio-pollutants, are characterized with:

^■ lack of self-reproduction of the species and with lack of valuable fish and other aquaculture species or only single pieces of them;

^■ "flowering" and "dullness" of the water during the summer and winter months of the year respectively;

^■ biological overloading, characterized with the existence of unlimited number of phyto- and zooplankton as well as with uncontrolled-overpopulation with "weed- like" fish of no importance, "weed-like" clams , with a coastal line and the reservoir as a whole abounding in superior and inferior vegetal species;

^■ deviations from the norms required, proven by physicochemical analysis of the water.

After that the first stage of the method, which includes cleaning of the water from bio- pollutants, namely: reducing the harmful "weed-like" fish species to the biological minimum limit by means of catching them with operculum nets, drag-nets, traps, "delyan" and other fishing appliances, has to be implemented in accordance with the invention. The reservoirs are cleaned also from superior and inferior water plants, from benthos changes and accumulations - if possible a meliorative intervention of the bed of the water reservoir should be performed.

The "weed-like" fish species, clams and superior and inferior water plants are self- settled with the help of the water bird species, wind or in another way. These species are more resistant to changes, so reducing them to the possible minimum does not mean reducing them to a given number but rather reducing them to a number which will not cause water pollution. After the cleaning of the water or in parallel with it, the second stage of the method, in accordance with the invention, should be applied, where the aquacultures are made up in a way which allows for all types of food in the reservoir to be used most sufficiently.

The main groups of aquacultures are defined, depending on the character of the water pollution - fish, crabs and clams, which taken together form a Biological philter.

According the invention, the Biological filter is implemented by means of selection, at a given proportion of the groups of aquacultures, living in the reservoir and self-regulating the water pollution, through transfer of economically valuable biological species and their unification (adaptation to the environment) until reaching a useful balance among the species, living in the reservoirs, while no additional (artificial) food is provided in it.

According the invention, the following groups of fish should be used for formation of the Biological filter: plankton-eating (Pelegic), benthos-eating bottom, plant-eating and fish of prey, including crabs and clams.

The percentage proportion of the various groups in the Biological filter is the following: plankton-eating - from 6% up to 12%, benthos-eating bottom - from 26% up to 71%, plant- eating - from 14% up to 37%, fish of prey from 5% up to 30%.

According the invention, the groups of aquacultures in the Biological filter include predominantly:

White carp (Hypophalmichthys molifrix VaI.) — the content of its food includes all groups of plankton duckweeds - green, blue-green and diatom duckweeds. The distance between its gill stamens almost does not change during its whole life and variates between 20 and 45 micrones.

Bighead carp {Aristichthys nobilis Rich.) - it feeds on both zooplankton (Daphnia, Monies, Bosmina, Alona and other) and phytoplankton.

Paddlefish (Polyodon spathula WaI.) - feeds on plankton, also called "live plankton strainer".

Sturgeon fish (fam. Acipenseridar) - feed on mollusks, worms, larvae, "weed-like" fish and other from the bed of the basins. They are valuable not only for the ecosystem but also from an economical point of view. Grass carp {Ctenopharyngodon idella VaI.) - feeds on superior water plants (rush, reed and other). It willingly eats dry plants and other weeds, which have got into the reservoir basin.

Chinese carp (Mylopharingodon piceus Rich.) — feeds mainly on clams.

Bigmouth buffalo (Ictiobus caprinellus VaI.) - unpretentious plankton-eater.

Black buffalo (Ichtiobus niger Raf.) ~ feeds on benthos and zooplankton, but during the summer period mainly with benthos.

Tench (Tinea tinea L) feeds on benthos organisms, found at the bottom of the reservoir.

Rainbow trout (Salmo irideus Gihb.) — feeds on rough fauna and small "weed-like" fish.

Largemouth bass (Micropterus salmoides Lae.) — feeds on bigger "weed-like" fish.

Perch-pike (Stizostedion lucioperca L.) — feeds on smaller "weed-like" fish.

Pike (Esox lucius L) - biological meliorator, feeds on both small and big "weed-like" fish.

European sheat fish (Silurus glanis L) — feeds on all sizes of "weed-like" fish.

Canal sheat fish (Ictalurus punctatus Raf.) -omnivorous bottom fish.

Carp (Cyprinus caprio L) -omnivorous bottom fish; and other.

For the purpose of prevention of the appearance of ill fish in the reservoir and eventual epidemic Crayfish (Astacidae - Astacus liptodactylus Esch.) and/or other crab species, resistant to the living conditions in the reservoirs, should be populated.

Integral part of the Biological filter, participating in the formation of the environment, are the clam species living in the reservoirs such as Unio, Anodonta and other.

It should be taken into account that the above mentioned main classification of the types of aquacultures, included in the Biological filter according their way of expectoration, is not absolute because all aquacultures complement one another in the food-chain under certain circumstances.

For example:

■ White carp is included also in the group of the plant-eating;

■ The Carp, which is mainly classified as a benthos-eating bottom fish is also an. omnivorous fish; ■ In the menu of the Bighead carp are included both zooplanktons and phytoplankton. At the age of one the percentage is 1 to 1 and later on the consumption of plankton is in favour of animal plankton - zooplankton.

■ In their early age all aquacultures feed on plankton.

■ The crabs, due to their function, are classified in the group of the fish of prey.

■ According the method, subject to the present invention, the clams are included in the group of the feeding on benthos.

After planning out the Biological filter comes the third stage of the method, subject to the invention - the introduction and population of the specific for the reservoir Biological filter i.e. artificial fish breeding,

Fish breeding should be performed during spring or during autumn. Autumn breeding is preferable because the fish recovers from the transportation, gets used to and adopts to the water reservoir and in early spring it starts to feed and get bigger. This leads to higher productivity of the fish and respectively to a more effective cleaning of the water. The water regime and the biological fish reproductivity of the Biological filter influence the density of culture (the number of fish during breeding). The number offish during breeding is defined by the quality of the reservoirs and by their pollution and it can vary between 150 and 600 pieces of aquaculture per decare. In case of considerable decrease of the number of biological pollutants ("weed-like" fish, "weed-like" clams and the existence of superior and inferior plants in the reservoir) and with regard to the higher fish productivity, their number can be reduced preferably between 200 up to 400 pieces of aquaculture per decare, more preferably between 150 up to 250 pieces of aquaculture per decare. The best breeding effect is achieved when the breeding material of one year olds is with weight from 30 to 50 g and of two years olds with weight from 200 to 300 g.

If the reservoir is bred with one year old breeding material fishing should not be performed during the first two years so that industrial shoals can be formed. When the breeding is made with older breeding material, fishing should be performed within a year because if the fishing is postponed or delayed not only fish productivity , respectively the cleaning of the waters for the given year, will be reduced, but also the fish left in the reservoir will have a negative influence on the efficiency of the Biological filter for the coming years. In this case the quantity of old fish in the reservoir, which uses less of its feeding resources — the biological pollutants, the superior and inferior plants, the "weed-like" clams and the benthos changes- will increase.

Every year after the draught is completed, a report about the species and the quantity of the breeding should be prepared on the basis of the level of pollution and the type of biological pollutants in the water.

After a period of three years a correction and replacement of the Biological filter should be made.

During the three-years period the care for the Biological filter should be constant.

Water is part of a living organism and a home of all organisms inhabiting it and depending on it. High temperatures, rain, pollution and every alteration and change in the atmospheric fluctuations have influence on the flora and fauna in the water reservoirs.

Having in mind the abovementioned, considerable part of the method, subject to the invention, consists in periodical monitoring of the ichthyo fauna and flora of the reservoirs during a three-years period, after which the correction and replacement of the Biological filter should be made.

The monitoring of the reservoir is made on a daily, weekly, monthly and seasonal basis.

By means of a daily visual monitoring of the reservoir the following is observed:

• Vegetation - with regard to the formation of "flowering", increase or decrease of the areas covered with vegetation, what is its colour and how it affects the change in the colour of the water in the reservoir.

• Fish population - with respect to:

° is the situation normal, is it migrating in its usual way;

° the existence of ill fish;

° is the fish reproducing itself;

° are the small predators hunting and so on.

• The "behaviour" of the water with regard to : ° cleanliness and pollution;

° freezing and unfreezing of the mirror of the reservoir; ⁰ everything, concerning a change away from the usual situation, depending on the season.

The temperature indicators of the surface and of the lower layers in given constant depths and situated at randomly selected locations at the reservoir should be noted down. Temperature indicators should be counted twice a day during spring, summer and autumn and once a day during winter at strictly defined hours.

A map should be drawn and the currents and the turning of the water temperature layers should be monitored.

The purpose of the weekly monitoring is to follow the condition and the fitness of the water - a physicochemical analysis is performed for the following indicators for first-grade water according Bulgarian State Standard (BSS), in compliance with Order No. 7/1986 of the Ministry of Agriculture of R. Bulgaria;

• pH - >6.5-8.5 pH units

• permanganate oxidizability - up to 10 mg O₂/l

• ammonium nitrogen — up to 0.10 mg/1

• nitrite nitrogen - up to 0.002 mg/1

• nitrate nitrogen - up to 5.0 mg/1

• general solidity — up to 7.0 mg

• phosphates - up to 8.2 mg/1

• insoluble substances - 30 mg/1

• dissolved oxygen - up to 6 mg/1

The samples should be taken from randomly selected, but permanently fixed depths and location points in the reservoir during the three-years period - from the water supply entrance, from the inside part of the water reservoir (from one or more places, depending on its area), and from the vicinity of the water-taking installation. The physicochemical analyses can be made in a private laboratory or in the regional or other centers.

The monthly monitoring consists in catching aquaculture species, included in the Biological filter , performing a check up and dissection. The indicators for weight, length, size and health condition of the species should be noted down. Their development, eventual mutations and diseases should be monitored. The seasonal monitoring includes:

° the periods of freezing-unfreezing of the reservoir and the thickness of the ice;

° spawning;

_° the water level;

° muddiness and cleanliness of the water.

Exceptional (additional) samples of the water and of the aquacultures are taken obligatorily in case of military actions, chemical and/or biological pollution of the region and of the water sources supplying the basin, prolonged raining, snowing and freezing, droughts, "nonadequate" behaviour of the aquacultures, included in the Biological filter.

All data from the yearly and all other monitoring should be recorded in a diary for the purpose of making analysis and drawing conclusions with regard to the appropriateness of the measures and changes applied.

After the three-years period is over the Biological filter should be replaced (by means of operculum nets, drag-nets, traps, "delyan" and other fishing appliances).

After considering the quantities of the physicochemical pollutants, the dissolved oxygen, the pH of the water, the indicators for water solidity, the areas covered with vegetation and the quantity of "weed-like" species, as well as all other indicators, concerning the fitness and the cleanliness of the water during the past three-years period and the draught, a scheme of the fish breeding should be made for the purpose of replacing the old Biological filter with a new one.

Advantages of the method, subject to the invention

They consist in:

• the "flowering of the water gradually stops and the quantity of oxygen in the reservoirs increases;

• a self-reproduction in the system starts;

• no chemicals and preparations are used for influencing the ecosystem and the water;

• in the reservoirs, processed under the method, subject to this invention, no additional (artificial) food is brought in;

• saving of materials in the treatment stations and respectively cost saving for treatment of drinking water, communal, agricultural and industrial water; • maximum level of purity of the water is achieved in accordance with the standards.

Examples for implementation of the invention

The invention is illustrated with the following examples, which do not limit its application in other cases as well

Example 1

In reservoirs with biologically polluted water and overloading of the food-chain

.The condition of the reservoirs is characterized with:

■ considerable change of the pH of the water;

■ the water solidity indicators are not within the norms;

^■ low free oxygen content;

■ oversaturation with carbon dioxide and other chemical elements, harmful for the water quality and for the organisms living in it;

■ overpopulation of the reservoirs with undersized "weed-like" fish species of no importance;

■ apparent ceasure of self-reproduction, due to overloading;

■ coastal line, covered with superior water plants;

■ dirty bed and mutation in the benthos organisms;

■ phyto- and zooplankton overloading and quantitative increase;

■ "flowering" and "dullness" during summer and winter months respectively;

■ the number of valuable aquaculture species, participating directly in the process of cleaning of the water in the reservoirs, is reduced to single pieces.

In the first stage all fish species, inhabiting the reservoir, are obligatorily taken away with the help of fishing appliances such as operculum nets, drag-nets, traps, "delyan" and other and reduced to the possible minimum.

A Biological filter is formed from the following species and quantities of aquacultures: Carp - 210 pieces per decare

Sturgeon fish - 10 pieces per decare

Canal sheat fish - 30 pieces per decare White carp - 70 pieces per decare Bigmouth buffalo - 10 pieces per decare

Bighead carp - 20 pieces per decare

Paddlefϊsh - 40 pieces per decare

Grass carp - 30 pieces per decare

Tench - 10 pieces per decare

Rainbow trout - 30 pieces per decare

Largemouth bass - 10 pieces per decare

Perch-pike - 10 pieces per decare

Chinese carp - 60 pieces per decare

European sheat-fish - 10 pieces per decare

Crayfish - 10 pieces per decare

Freshwater clams - 40 pieces per decare

Saplings consist of one year olds with weight from 30 up to 50 g., where the fish of prey is smaller in size than the nonpredators and the crabs are sexually mature. The Biological filter is introduced in the cleaned water reservoir; first are put the nonpredatory species, then the predatory ones.

Afterwards a permanent daily, weekly and monthly control and monitoring are performed and the data is recorded in a diary. During the seasonal monitoring, depending on the overloading of the water reservoir with biological pollutants, superior and inferior water plants, the presence and the quantity of various fish species of no importance, a correction of the valuable aquaculture species, used in the Biological filter, is made.

Example 2

Canals, covered with vegetation and with overloaded bio-environment

The canals, used as overflow drain and for irrigation in agriculture, due to their shallow water horizon, the stale water and a number of other reasons, often get stuffed and covered with various forms of superior water plants. Various benthos forms and plankton variations are developed. The cleaning of these pollutants and their use for economical purposes can be successfully realized with the help of the method, subject to the invention, but since the water is oxygen deficient and there exists a danger of "dullness", the total number of the aquacultures, brought in with the Biological filter should not exceed 150 pieces per decare and the interrelation should be in favour of the fish of prey. The formed Biological filter includes:

White carp - 5 pieces per decare

Bigmouth buffalo - 10 pieces per decare

Black buffalo - 10 pieces per decare

Tench - 10 pieces per decare

Grass carp - 50 pieces per decare

Largemouth bass - 10 pieces per decare

Pike - 30 pieces per decare

Canal sheat-fish - 20 pieces per decare

Crab - 5 pieces per decare

The fish breeding is made with two years old breeding material with weight between 200 and 300 g, with no exception for the predatory species. Afterwards a permanent daily, weekly and monthly control and monitoring are made and depending on the overload with biological pollutants some corrections in the Biological filter are introduced.

Example 3

New reservoirs with yet not overloaded bio-environment at the food-chain

A biological filter with the following species and quantities of aquacultures is formed:

Carp - 125pieces per decare

White carp - 40 pieces per decare

Bighead carp - 10 pieces per decare

Paddlefish - 20 pieces per decare

Grass carp - 15 pieces per decare

Tench - 5 pieces per decare

Rainbow trout - 15 pieces per decare

Sturgeon fish - 15 pieces per decare

Crayfish - 5 pieces per decare

Preferably saplings from plankton-eating, benthos-eating and plant-eating species should consist of two years olds with weight 200-300 g, and the predatory species should be smaller in size than the rest; for this purpose a one year old breeding material with weight from 30 up to 50 g should be used. The crabs that are brought in should be sexually mature.

Afterwards a permanent daily, weekly and monthly control and monitoring should be made. A new scheme and correction of the valuable aquaculture species, used in the Biological filter, is made depending on the loading of the reservoir with biological pollutants.

Example 4

New reservoirs with possibility for a more intensive growth of the aquacultures, included in the Biological filter, for fishing purposes:

Carp - 130 pieces per decare

White carp - 25 pieces per decare

Bighead carp - 15 pieces per decare

Grass carp - 5 pieces per decare

Tench - 3 pieces per decare

Rainbow trout - 10 pieces per decare

Crawfish - 3 pieces per decare

Freshwater clams - 10 pieces per decare

The nonpredatory species included in the Biological filter should preferably be two years olds with weight 200-300 g; the Ranbow trout should be one year old and the Crayfish is brought into the reservoir in the second year and should be sexually mature.

Example 5

Reservoirs with biologically polluted water and loaded at the food-chain

The condition of the reservoir is characterized and evaluated in accordance with the indicators, stated in Example 1, while the formed Biological filter includes: Carp - 160 pieces per decare

White carp - 40 pieces per decare

Bighead carp - 15 pieces per decare

Chinese carp - 30 pieces per decare

Black buffalo - 10 pieces per decare Bigmouth buffalo - 10 pieces per decare

Paddlefish - 10 pieces per decare

Grass carp - 16 pieces per decare

Sturgeon fish - 10 pieces per decare

Tench - 16 pieces per decare

Pike - 10 pieces per decare

Crab - 13 pieces per decare

Freshwater clam - 60 pieces per decare

The introduced material, included in the Biological filter, should consist of two years olds with weight 200-300 g, as an exception the fish of prey - Pike and Chinese carp should be one year old for the purpose of preservation of the nonpredatory species. The crabs are sexually mature.

Industrial applicability

The applied method allows for the considerable increase of the efficiency in recovering the broken ecological balance in natural and artificial water reservoirs by achieving not only cleaning of the water in the reservoirs in a nature-friendly way, but also by realizing fish production of economically important aquacultures.

The method is realized with simple equipment and the process of preparation of the reservoirs and the formation of the respective Biological filter consists in simple operations, which can be performed mechanically.

The realization of the technology in accordance with the method explained above, will allow for fast and economical fulfillment of the standard indicators applied to water used in households, agriculture and industry and it will considerably ease and decrease the cost of its treatment in the water treatment stations.

Claims

PATENT CLAIMS

1. Method for biological cleaning of reservoir waters by means of formation of controlled ichthyo fauna and flora in the reservoir, characterized by the following operations:

^■ balanced taking out of the "weed-like" fish present in the reservoir and reducing its number to the limit of the biological minimum, of the superior and inferior plants, cleaning of the dirty bed from benthos variations and accumulations;

^■ formation of biological filter, including plankton-eating, bottom benthos-eating, plant-eating and predatory groups of aquaculture with the following proportion in percentage: plankton-eating - from 6% up to 12%, benthos-eating bottom - from 26% up to 71%, plant-eating - from 14% up to 37%, fish of prey - from 5% up to 30%.

■ depositing of the Biological filter in the reservoir with density of culture from 150 to 600 pieces per decare, preferably from 200 to 400 pieces per decare,- more preferably from 150 to 250 pieces per decare;

■ performing of periodical - daily, weekly, monthly and seasonal monitoring of the ichthyo fauna and flora and of the water in the reservoir;

■ introduction of corrections in the content and in the density of culture of the Biological filter on the basis of the periodical seasonal monitoring;

■ preparation of a plan and a scheme for fish breeding, for the purpose of replacement of the Biological filter after a period of three years on the basis of the monitoring.

2. Method, in accordance with claim 1, where "weed-like" fish that can be taken out includes: rudd, goldfish, carassius , carp and other.

3. Method, in accordance with claim 1, where the aquaculture species from the group of the plankton-eating, that are brought in, might include: Bighead carp, Paddlefish, Bigmouth buffalo and other.

4. Method, in accordance with claim 1, where the aquaculture species from the group of the benthos-eating bottom fish, that are brought in , might include: Black buffalo, Tench, Canal sheat-fish, Carp, clams and other.

5. Method, in accordance with claim 1, where the aquaculture species from the group of the plant-eating, that are brought in, might include: Grass carp, White carp and other.

6. Method, in accordance with claim 1, where the aquaculture species from the group of the fish of prey that are brought in, might include: Chinese carp, Rainbow trout, Largemouth bass, Perch-pike, Pike, European sheat-fish, Sturgeon fish , Crayfish and other.