Pond with filtered water

The invention relates to a pond (2) with filtered water having a relatively large and free surface. The pond (2) is laid out along a polluted surface water (1) having a large rate of flow or quantity of water, and a filter dam (3) is built between the polluted surface water (1) and the pond (2) of filtered water. The pond (2) according to the invention can be employed as a water intake for drinking water and/or for water for agriculture and/or for industrial water, and as a recreational area (4,5).

THE TECHNICAL FIELD 
The invention relates to a pond with filtered water having a relatively 
large and free surface, i.e., a small artificial lake whose bed is filled 
with treated and clarified water which is prevented from being polluted. 
STATE OF THE ART 
The pollution of surface waters, such as rivers, ponds, lakes or seas has 
assumed terrifying proportions. Nowadays, many surface waters are unfit 
not only for drinking and bathing, but also for industrial purposes. These 
waters should more and more be referred to as "dead water", in which life 
in the biological sense is impossible. 
Tackling the problems of supplying industries, agricultural establishments, 
and communities with adequately clarified water which is pure from the 
hygienic and sanitary points of view becomes more and more urgent. Various 
proposals have been advanced to solve these problems: 
When the surface waters are unit for bathing, beaches are constructed with 
basins which perform the function and meet the requirements of the 
recreational area. This concept is followed in the terrain regulation of 
the power stage system in Gabcikovo-Nagymaros on the Donau. However, these 
beaches have a very limited capacity. The construction, operating and 
maintenance costs are extremely high and they can be used to perform one 
function only. 
The aquosity of a water-producing region can be increased by means of 
ground water basins, whose water is clarified preliminarily. This was 
copied in various publications. We refer to the Hungarian journal 
Hidrologiai Kozlony (Hidrological Communications) No. 7/1976 (an article 
by Karoly Gefferth) and 1/1975 (an article by Drs. Takacs and Andrik). In 
these articles, the methods are hydrobiological and bacteriological 
effects of the enrichment of the ground water are explained. However, also 
the ground water basins can perform only one function; with the 
preliminarily clarified water only the quantity of water of the 
water-producing facility can be increased. 
In regions with good ground water aquifers, the small quantity of water 
that can be obtained is increased through supply with preliminarily 
clarified water. This solution has been copied by Maria Bauer after a 
Dutch example (Hidrologiai Kozlony, No. 8/1973). It is very uneconomical, 
the production and operating costs are high and the water thus obtained is 
unfit for human consumption. 
The water of the high tides in spring is less polluted. Thus, it is stored 
in safety reservoirs and consumed at low tides. This concept is employed 
in Hungary in the water regime between Tatabanya and Szekesfehervar. 
However, these safety reservoirs have widely varying levels and can be 
used for one purpose only. They are unfit for use in a recreational area. 
Thus, most prior art solutions require the water to be treated 
preliminarily, because the pretreated water is stored and finally 
consumed. Many proposals are known for treating water. 
Published West German Pat. DT No. 1 918 682 describes a filter system in 
which a plurality of parallel filter zones filled with a filter material 
are provided and a channel is constructed between the filter zones which 
is surrounded on all sides by a porous membrane. 
Published West German Patent Application DT No. 2 400 497 describes a 
method for the biological improvement of river, pond, and lake water, in 
which a portion of the water is taken from the polluted pond and fed to an 
aerated reservoir containing a filling material, such that the water 
trickling through the reservoir is enriched up to the saturation point and 
is then allowed to flow back into the pond. This method can only be 
employed if the pond is slightly polluted. 
The other prior art solutions: (West German Pat. No. 2 610 334: Method for 
the mechanical and chemical treatment of liquid media loaded with solids 
and ionic pollutants in a filter bed consisting of granular material; West 
German Pat. No. 2 636 094: Method for the regeneration of water, i.e., to 
raise the energy level in water and, thereby, its biological value; West 
German Pat. No. 2 530 722: Method for the nitrification, demanganization 
and deferrization in fixed beds and biological fixed-bed reactors) can 
only be implemented in laboratories, but only with small quantities of 
water. In no way can they be applied to clarify a quantity of water needed 
for a pond with filtered water. 
Summing up, it can be said that the prior art techniques still have not 
solved the problems of water treatment by a long shot. In general, the 
proposed solutions have only one function. They solve only one problem, 
are highly uneconomical, and a great deal of money is required to 
construct them. 
PRESENTATION OF THE INVENTION 
The primary object of the invention is to solve the problems of water 
pollution in large surface waters and at the same time to overcome the 
inadequacies of prior solutions. 
In order to solve the above problems, we have developed the idea of storing 
the clarified water in a pond, to treat the large quantity of water 
required not with special filter systems, but with a suitably constructed 
filter dam, and finally to lay out the pond thus built and filled with 
filter water next to the polluted surface water. 
Therefore, the present invention relates to a pond having a relatively 
large and free surface. The development of this idea, i.e., the invention 
itself, is seen in the fact that the pond is laid out with a large 
quantity of water along a polluted surface water and to build up a filter 
dam between the polluted surface water and the pond with filtered water. 
In this way, the pond embodying the teachings of the invention has a triple 
function: production and storing of water as well as recreation. 
Furthermore, the construction of the pond is very simple and inexpensive 
and the operating costs are low. The construction of the pond can be 
combined with other water management tasks, water assessments, elimination 
of water damage, etc., as well as with the output from mineral stock. All 
in all, it can be stated that the pond with filtered water as proposed by 
this invention is cost effective. 
The filter dam in accordance with the invention can be constructed in such 
a way that it can be mechanically, chemically, biologically and 
bacteriologically filtered by it. The filter dam can be constructed as a 
natural or artificial filter dam. In the first instance, the ground that 
has grown on the spot has adequate filtering characteristics which can be 
exploited during the construction. In the latter case, the corresponding 
filtering characteristics of the filter dam must be adjusted with banked 
earth transported thereto that has good filtering properties or with 
artificial materials. It goes without saying that both solutions can be 
combined. 
The term "filter dam" in this context can be interpreted in many different 
ways. As an example, when the grown soil has filtering characteristics 
which are adequate for the given task, an impermeable dam can be built as 
filter dam. The polluted water will inevitably flow through the soil with 
good filtering characteristics and will be adequately treated. Such a 
filter can, for instance, be employed in a bay of a surface water in which 
the bay is separated from the polluted body of water by an impermeable dam 
constructed on the soil with good filtering properties. The polluted water 
is then lifted off the bay and the water flowing thereinto is treated 
through the grown soil. 
According to the invention, the pond with filtered water can also serve as 
a water base. The water can be obtained from the subterranean stock of 
water through shore filtering wells and board wells or from the stock of 
water above ground by means of surface adits, drain weirs, or booster 
pumps. In this way, the pond can also be a safety water base which stores 
the filtered water during peak pollution periods and pollution disasters. 
"Twice-filtered" water can be obtained from the subterranean stock of 
water. 
The surroundings of the pond may be subjected to the demands on water 
purity in conformity with the terrain control. Thus, the polluted water or 
the waste waters of the surroundings are prevented from getting to the 
pond. 
This terrain control means that the small water courses of the water 
catchment grounds are guided into colloid-filtering or biological 
clarification ponds and are treated therein. The clarification ponds are 
connected with the pond with filtered water. The waste waters of the 
surroundings of the pond can be guided in closed waste water channels and, 
after appropriate treatment, conducted into the pond. In extreme cases, 
when these waters are very polluted, they can be introduced into the 
surface water through reversing water courses or reversing sewer ducts. 
The third function of the pond embodying the teachings of the invention can 
also be performed through the terrain control: recreational areas can be 
constructed on its banks. To make the pond also agreeable for bathing, a 
bed floor may be grown and/or built thereon. 
Further details of the invention will be apparent to those skilled in the 
art from the following description of one specific embodiment thereof as 
illustrated in the attached drawings.

THE BEST PRACTICAL EMBODIMENT OF THE CLAIMED INVENTION 
FIG. 1 shows the site plan of a practical embodiment of the pond 2 
embodying the teachings of the invention and filled with filtered water; 
it has actually been built. 
The pond 2 with filtered water has a relatively large and free surface. 
Hence, it is distinguished from this type of prior art water reservoirs in 
which the water is filtered through the bottom and which have a relatively 
small surface or no free surface at all, such as wells. 
The pond 2 is constructed along a surface water 1 which, if it is a river, 
has a large rate of flow or, if it is stagnant water or swamp water, has a 
large quantity of water and whose water has become more or less polluted. 
Between the pond 2 and the surface water 1 a filter dam 3 has been built 
which separates the polluted water of the surface water 1 from the treated 
water of the pond 2. In this embodiment, recreational areas have also been 
built around the pond 2, an undeveloped recreational area is denoted by 
the reference numeral 4 and a developed recreational area by the numeral 
5. 
In this embodiment, the pond 2 is provided with water intakes. On the banks 
of the pond, shore filter wells are arranged in various rows, the ground 
area they occupy is denoted by 6. Board well 7 has been sunk in the pond 
2. Twice-filtered water can be drawn off the shore filter wells 6 and the 
board wells 7 because here, too, the water is filtered for the second time 
through the bottom of the bank or of the bed of the pond 2. A water 
catchment 8 on the surface of the pond 2 and a drain weir 9, as well as a 
booster pump 10, serve as water intakes for the stock of water above 
ground. The drain weir 9 can also function as a high-tide conduit. The 
booster pump 10 may be provided with a fairly long suction pipe, with the 
result that the more heavily polluted water encountered in the vicinity of 
the bottom of the pond 2 can be lifted to the surface water 1. 
An orographic water-catchment terrain with its border (broken line) is 
indicated by the reference numeral 11. Small water courses 12 rise from 
here and from a geological water catchment terrain 24. The water of these 
small water courses 12 is conducted into the colloid-filtering and 
biological clarification pond 14 and thereafter into the pond 2 or thru a 
reversing water course 13 into the surface water 1. 
The waste water of the recreational areas 4 and 5 is collected in the 
closed sewer duct 15 and guided either to a sewage plant 16 or to the 
surface water 1 through a reversing sewer duct 18. The sewage plant 16 is 
connected with the pond 2 by means of a collector 17. 
Various functions can be performed by means of the pond 2 embodying the 
principles of the invention. Drinking water can be obtained from the shore 
filter wells 6 and from the board wells 7. With the water catchment 8 or 
with the drain weir 9 or the booster pump 10, water can be obtained for 
direct irrigation or as compensation water and, after preliminary 
treatment, as industrial water. 
FIG. 2 is a cross-sectional view of the pond 2 of FIG. 1 showing the 
arrangement of the shore filter wells 6 and of the board wells 7. An 
operating water surface of the pond 2 is denoted by 21, the height of the 
filter dam 3 by 23, a minimum water level by 19, and a maximum water level 
of the surface water 1 by 22. 
FIG. 3 is another cross-sectional view taken along the line III--III of 
FIG. 1 showing the terrain control of the surroundings of the pond 2. 
Due to the quantity of superfluous water, the stock of water of the pond, 
which is continually and dynamically renewed, has positive water budget. 
This water budget of the pond 2 can be controlled by means of the water 
intakes. In this way, the quantity of water trickling through the filter 
dam 3 can be simultaneously controlled. 
The filter dam 3 is dimensioned in accordance with the surface variation 
occurring between the minimum water 19 and the maximum water 22 of the 
surface water 11 for a specified filtration/seepage boundary. This 
dimensioning determines the quality of the water of pond 2. The water 
filtered through the filter dam 3, whose quality is predetermined in this 
manner, also eliminates the pollution effect of the precipitation and of 
the use of the pond. Thus, the filter dam 3 is constructed in accordance 
with these requirements and is made from natural and/or artificial 
materials, as mentioned earlier. 
The filter dam 3 is operated as a filter membrane. Its surface, but also 
the deeper layers, can be heavily polluted, even clogged. Therefore, the 
filter dam must be cleaned periodically, it must be maintained. This can 
be done in two ways: 
through flushing, in which owing to the very low minimum water level 19 of 
the surface water level 1 a reversed current occurs. The seepage in the 
direction opposite to the normal direction carries into the surface water 
1 the pollutants that have been deposited on the surface of the filter dam 
3; 
through mechanical treatment, in which the surface of the filter dam 3 is 
scraped off, worn off, or ripped, or at least eroded in part, and 
occasionally fully modified. 
Finally, it should be mentioned that in addition to the functions discussed 
earlier, the pond 2 embodying the teachings of the invention can also be 
exploited for continuously improving the quality of a surface water 1. The 
polluted water of the surface water 1 is continuously cleaned through the 
filter dam 3 and the filtered water is returned from the pond 2 to the 
surface water 1. When a number of such ponds 2 are constructed along a 
polluted river, with which the polluted water is continually clarified, 
the quality of the water of the surface water can be substantially 
improved. 
The practical usefulness of the invention for industry is apparent from the 
remarks outlined above. Moreover, the invention is of great significance 
not only for industry and agriculture, but it also contributes to 
combatting the human problems created by environmental pollution.