DK153135B - RED ZONE PLANT TO CLEAN PURE WATER - Google Patents

Description

DK 153135 B

The invention relates to a root zone plant for the purification of impure water comprising a defined mass of a growth substrate planted with sump plants such as eaves (Phragmites communis), reed (Schoeno-plectus lacustris) and downy hammer (Typha), means for supplying impure water to the substrate mass means for discharging purified water.

Such wastewater treatment plants have gained widespread use in recent years.

The water purification achieved with a root zone plant is based on a complicated interaction between the substrate mass, the sump plant root system and the microflora in the substrate mass.

The microflora consists partly of aerobic bacteria and partly of optional anaerobic and obligate anaerobic bacteria. The ability of the aerobic bacteria to react with the organic substances supplied with the wastewater is contingent on the oxygen supply that takes place through the intercellular air supply system (aerenchym) of the sump plants that conducts air to the growth parts below the water surface.

The above mentioned interaction also includes the substrate mass, which serves partly as a substrate for the root system of the plants and partly as a supplier of various nutrient salts for plants and microorganisms.

A disadvantage of the known root zone plants is that a considerable amount of time passes, e.g. up to 2 years, from the time the planting takes place and to the time when the plant is fully operational. This is because the plants need a long time to develop a branched root system, which is a prerequisite for plant efficiency.

This disadvantage is eliminated by the root zone system according to the invention, which is characterized by the fact that the substrate mass is arranged in an upwardly open, transportable tank, possibly with an overlay, however, so that the tank is still open upwards.

By using such a tank, the construction of a root zone plant can be started at such a time that the plant is fully functional when it is to be delivered. In practice, this can be done by planting such a number of tanks with substrate-35 mass, which corresponds to the expected sales 2-3 years into the future.

The tank is preferably a plastic box or a metal or wooden box, e.g. of waterproof plywood coated with a waterproof plastic film, e.g. with a thickness of approx. 2 mm. The tank, which is preferably rectangular and e.g. has a length of

DK 153135 B

2 approx. 6 m and a width of 2.4 m is preferably filled with a substrate mass, such as soil, up to a height of 60-80 cm.

The rectangular tank preferably contains at one end a filling of a particulate inorganic material such as limestone, marble pieces and shingles, and at its opposite end has another filling of an inorganic material. In the latter, a drainage pipe is preferably laid for draining the purified sewage.

Instead of providing fillings at the ends of the tank, open channels may be formed here which are delimited relative to the substrate mass by means of water-permeable partitions, e.g. may take the form of a perforated plastic wrap or textile fabric.

As needed, larger and smaller tanks may be used, and the tanks may be provided with such interconnecting means that they may be connected in parallel.

Upon delivery of a plant according to the invention, the tank or tanks are transported out to the place of use and placed here on the ground or in specially designed, possibly molded, holes therein.

A particular advantage of the root zone plant according to the invention is that it is environmentally friendly, since the risk of leakage of unclean water and contamination of the surrounding soil is completely eliminated.

Furthermore, the system can easily be replaced if, for any reason, it should lose its functionality.

Finally, when using a plant according to the invention, one is independent with regard to the location of the plant, for example. no special soil conditions need to be taken into account.

For safety reasons, a fence is preferably attached to the top of the tank.

30 The plant described is particularly useful for wastewater treatment. However, it should be understood that it can also be used for the purification of other kinds of unclean water e.g. water with an undesirably high content of salts. Thus, it has been found suitable to reduce the content of hardness-causing salts and other salts, such as nitrates, phosphates and heavy metal salts in groundwater.

Also water containing undesirably large amounts of organic material can be purified in the plant.

The invention will now be described in more detail with reference to the drawing, in which

DK 153135B

3 FIG. 1 is a top view of a root zone plant according to the invention; and FIG. 2 shows a vertical section along line II-II through the root zone system shown in FIG. First

5 In the drawing, 1 denotes a rectangular box, the inside of which is lined with a waterproof plastic film 2. In the box 1 there is a soil mass 3 planted with sump plants 4 (Phragmites communis). At the right end of the box 1 is placed a filling 5 of an inactive material such as singles, and a corresponding 10 but narrower filling 6 is placed at the left end of the box 1. The latter filling 5 is arranged over a drain pipe 7.

The apparatus shown further comprises a handrail 8 enclosing the upper part of the box 1.

Using the plant according to the invention, impure water is introduced, e.g. wastewater, in the filling 5, from which it enters the soil mass 3 and moves in the direction towards the filling 6 and the drain pipe 7 therein.

During passage through the soil mass 3, the wastewater is purified to such an extent that the purified wastewater through the drainage pipe 7 can be supplied to natural recipients or used as fresh water without further purification.

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Claims (4)

A root zone plant for the purification of impure water comprising a defined mass (3) of a growth substrate planted with sump plants (4), means (5) for supplying crude water to the substrate mass (3) 5 and means (6,7) for discharging purified water, characterized in that the substrate mass is placed in an upwardly movable tank, transportable tank (1,2), possibly with cover, however, so that the tank is still open upwards. Root zone system according to claim 1, characterized in that the tank (1,2) is rectangular in shape and comprises at one end a filling (5) of a particulate, inorganic material for distributing the wastewater into the substrate mass (3). and at the opposite end a further filling (6) of a particulate, inorganic material for draining of purified water. A root zone system according to claim 2, characterized in that a drainage pipe (7) for draining purified water is laid down in the filling (6). Root zone system according to claim 1, characterized in that the tank consists of a metal or wooden box (1) which is internally coated with a waterproof plastic film (2). 25 30 35