Liquid purification or separation – Structural installation – Closed circulating system
Reexamination Certificate
2003-08-28
2004-12-14
Prince, Fred G. (Department: 1724)
Liquid purification or separation
Structural installation
Closed circulating system
C210S143000, C210S206000, C210S259000, C210S416200, C210S905000, C119S260000
Reexamination Certificate
active
06830681
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a device for holding water for accommodating and growing aquatic organisms, comprising a first chamber for holding oxygen-depleted water and a second chamber for holding oxygen-rich water, and a porous substrate which comprises micro-organisms and is in contact with the oxygen-depleted water and the oxygen-rich water.
The porous substrate which comprises micro-organisms in the device described here may be made from a very wide range of different porous materials, but it is preferable for the porous substrate to be made from a material which provides a large surface area for the growth and adhesion of micro-organisms, such as for example coarse sand, gravel, aragonite, coral fragments or coarse-ground shells.
The organisms which are grown and kept using the above device are intended in particular to be macro-organisms, such as for example fish, water plants, corals, sponges and molluscs; the device obviously also provides a suitable climatic environment for micro-organisms which are situated in and outside the porous substrate.
BACKGROUND OF THE ART
A device of this type is known from U.S. Pat. No. 4,995,980 and makes use of the principle that waste materials, originating, inter alia, from food for the macro-organisms kept in the water, diffuse from the oxygen-rich water to the substrate and the oxygen-depleted water, where the waste matter, in particular nitrate and nitrite, is reduced, so that the concentration of waste matter is limited. However, a drawback of this device is that ultimately waste matter still accumulates, and this accumulation may be harmful to the macro-organisms kept in the water. Moreover, this accumulation of waste matter results in the water becoming turbid, which is undesirable if the device is used to display animals and/or plants in the oxygen-rich water. In addition, the device has the drawback that the system is relatively unstable, i.e., for example in the event of the death of a macro-organism, a suddenly occurring large supply of a contaminating carbon source from the oxygen-rich water to the oxygen-depleted water, oxidation of the contaminating carbon source by micro-organisms leads to the oxygen-depleted water becoming completely anaerobic. Under completely anaerobic conditions, micro-organisms can form H
2
S, which can poison and, kill the macro-organisms which are present.
SUMMARY OF THE INVENTION
It is an object of the invention to overcome the described drawbacks, and to this end the device is characterized in that the first chamber is formed by at least part of the substrate, and a first circuit, having ail inlet and an outlet, which are in communication with the first chamber, is connected to at least the first chamber, and there are first passage means for passing oxygen-depleted water through the first circuit, and means for conditioning the oxygen-depleted water are in contact therewith.
The pores of the porous substrate will usually also contain oxygen-depleted water, which means that part of the second chamber lies within the porous substrate. When the porous substrate is laid directly onto the bottom of the device, the second chamber will lie substantially entirely within the porous substrate. Obviously, the invention also relates to a device as described in U.S. Pat. No. 4,995,980; it is the intention for the invention also to include embodiments of this type, in which the substrate or parts of the substrate and the chamber for holding oxygen-depleted water are positioned vertically along a side wall of the device.
In the present context, the term conditioning is understood to mean providing optimum conditions for the reaction of waste matter. The optimum condition can be judged from aspects such as pH, oxygen concentration, nitrogen concentration, carbon concentration, etc. The various characteristic features of the water and their application will be dealt with below.
The use of means which condition the oxygen-depleted water allows the condition of the oxygen-depleted water to be kept in a state which is optimum for the conversion of waste matter, so that the conversion of waste matter is influenced and increased.
In this context, it is expedient to increase the stability of the system by increasing the total volume of oxygen-depleted water. A large volume has a buffering action, since the composition of a large volume changes more slowly. This increase is achieved by incorporating the means for conditioning the oxygen-depleted water in a first circuit through which oxygen-depleted water passes.
In addition, the passage of oxygen-depleted water through the first circuit makes it possible to generate a first flow beneath the porous substrate, which comprises micro-organisms, in such a manner that pressure differences across the porous substrate, which comprises micro-organisms, are formed, generating a second flow of water through the porous substrate which comprises micro-organisms. The second flow can, inter alia, control the oxygen concentration in the oxygen-depleted water, the oxygen concentration preferably being kept between 1 ppm and 4 ppm. At an oxygen concentration of 1-4 ppm, there will be no formation of poisonous sulphur compounds, such as H
2
S, while reduction of nitrate and nitrite to form gaseous nitrogen by means of micro-organisms continues to take place.
In an expedient embodiment of the device, the means for conditioning the oxygen-depleted water comprise measurement and control means for measuring and controlling the composition of the oxygen-depleted water, and separating means for separating out sediment which is entrained in the first circuit.
As has been stated, it is essential for the quality of the oxygen-depleted water for the various characteristic parameters thereof to be controlled; in addition, for the aesthetic appearance of the device it is important to limit the quantity of sediment.
In an expedient embodiment, the measurement and control means comprise instruments selected from:
a) means for measuring the oxygen concentration
b) means for measuring the water temperature
c) means for measuring the pH
d) means for measuring the concentration of sulphur compounds
e) means for measuring the nitrogen concentration
f) means for measuring the carbon concentration
g) means for measuring the sediment concentration
h) means for measuring the redox potential
i) means for measuring the mineral concentration
j) means for injecting conditioning medium
k) control means for influencing the operation of the first passage means and/or the means for injecting conditioning medium into the first circuit in response to a deviation from a predetermined value which is recorded by one or more of the means for measuring constituents as described in a to j.
The advantage of an embodiment of this type is that, on account of the coupling of the control means to the measurement means, means for injecting conditioning medium and the first passage means, the control of the conditions of the oxygen-depleted water is effected automatically, with the result that continuous inspection by human observation is no longer required.
The control means may, for example, comprise a computer which comprises a program which, as a function of one or more measured water quality values and the deviation from a set value thereof, controls the passage means, such as pumps or injection means, in order to ensure that the set value is restored.
The injection means are used when the pH or the carbon concentration of the oxygen-depleted water deviates excessively from the set value; acid/base or a carbon feed source can be injected as required. The injection means per se generally comprise a storage vessel containing the agent which is to be added, a pump, a line and a nozzle opening out into the device.
The abovementioned measurement and control means may, for example, be incorporated in the first chamber and perform their task in this chamber. Obviously, the measured values for the various characteristic variables, especially in the case of large volumes of the first chamber, are primarily represe
Deveau Todd
Ecodeco B.V.
Prince Fred G.
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