Technical field of the invention The present invention concerns a system and a process for separating and collecting organic material from water used in fish hatcheries, as well as their use.

Background During the hatching of fish eggs a substance, hereafter called hatching liquid, is produced. The hatching liquid contains valuable proteins, enzymes and components thereof, and is dissolved in the water used in the hatchery. It is known that such proteins and active components are refined from various resources for use in various biochemical processes in food, cosmetics or pharmaceutical products, etc. From recent research it is also known that eggs, especially eggs from Atlantic salmon, contain large amounts of proteolytic enzymes and other valuable proteins that also have distinct advantageous effects.

There is presently no useful separation method for isolating and collecting the hatching liquid which is part of the water used in commercial hatcheries.

The most common hatcheries are based on a "flow-through" system; in this system the water flows continuously through the hatching system. The hatching liquid is here discarded directly to the waste water and the valuable proteins and enzymes are lost. As opposed to "flow-through" systems, a fish hatchery with recirculation of the water have the benefits of stable water quality and good results in terms of fish survival, less disease problems and better quality of the progeny. A potential problem is that the hatching of the eggs bring to the water dissolved proteins, which can result in high ammonia content and a poor water quality if said proteins are not removed. The removal of such proteins from the circulating water is often achieved by the use of a protein skimmer. The protein skimmer removes the dissolved proteins and other organic matter by use of air bubbles streamed through the water. The foam produced by said bubbles contains the organic matter (including proteins) formerly dissolved in the water, and said foam is discarded by spraying it with large amounts of water.

US patent no. 7,121,535 B discloses a protein skimmer for use in removing organic waste material from water. In said patent, the foam is discarded by spraying with water. No mention is being made of the possibility of, or potential means for, collecting the discarded organic matter.

The Norwegian patent no. 314594 Bl discloses a method for separating proteins dissolved in water from a fish egg hatchery by using filtration of the hatched salmon eggs through a cheese cloth.

As is clear from the above, there exist a need for a method of separating and collecting valuable organic matter from water, more particularly proteins and enzymes from water used in fish egg hatcheries.

Summary of the invention

The present invention provides a system, process and method of use for separating and collecting dissolved organic matter from water, more particularly proteins and enzymes from water used in fish egg hatcheries. In addition to enabling the collection of proteins and enzymes from water in fish egg hatcheries, the system according to the invention also provides a solution for obtaining water of improved quality when used in a hatchery where the water is recirculated.

The invention comprises a system for separating dissolved and/or suspended organic matter from water, comprising a protein skimmer wherein one end of a pipe is connected to a foam outlet of the skimmer through which foam generated in the skimmer rises and the other end of the pipe is connected to a vacuum pump. Said vacuum pump is connected to the pipe by an apparatus for separating air from liquids. Further, said apparatus is preferably equipped with an outlet for collecting the separated organic matter.

The apparatus for separating air from liquids is preferably a hydro cyclone.

The system may further comprise a filtration and/or sedimentation apparatus prior to the protein skimmer.

Further, the system may also comprise means for further purification and/or separation of the organic matter, said means may include for example gel separation or membrane filtration, and are preferably connected to the apparatus for separating air from liquids. The invention further comprises the use of the above-mentioned system according in the separation of proteins and/or enzymes from water used in marine species hatcheries and/or farming. Preferably, the water is from a salmon egg hatchery. The hatchery, from which the water to be purified is obtained, may use a "flow-through" water system or a system wherein the water is recirculated.

The invention further provides a process for separating dissolved or suspended organic matter from water, comprising the steps of:

- a) flowing water, containing said organic matter, through a protein skimmer; b) collecting and breaking down foam, containing organic matter, produced in the protein skimmer by use of vacuum suction;

c) separating the collected organic matter from step b) from air. In the process of the invention, the water is preferably obtained from a fish egg hatchery and the organic matter is hatching liquid.

Short description of the drawings Fig. 1 shows one embodiment of the invention comprising a protein skimmer and a hydro-cyclone separator 8.

Fig. 2 shows the top outlet 5 of the protein skimmer and the pipe 7. Detailed description of the invention

The invention provides a system, process and method of use for separating and collecting dissolved and/or suspended proteins and enzymes from water used in marine species hatcheries.

Fig. 1 shows one embodiment of a separation system according to the present invention comprising a protein skimmer combined with a hydro cyclone 8. The system has an inlet 4 through which water containing dissolved organic matter enter the aeration chamber 3 of the protein skimmer. The aeration chamber 3 comprises a grid of diffusers 2 near the bottom of the aeration chamber connected to a pump 1. The pump 1 blows air into the diffusers creating air bubbles. Organic matter dissolved in the water adheres to the air bubbles from the diffusers 2 and rises to the top outlet 5 of the aeration chamber forming a dense foam. The outlet 5 is connected by a pipe 7 to the hydro cyclone 8. An air pump 11, connected to the hydro cyclone 8, causes a vacuum to form in the pipe 7. The dense foam rises through the outlet 5 and into the pipe 7. When the dense foam is exposed to the lower pressure of pipe 7 the bubbles of the foam bursts and it is transformed into a viscous liquid and air. Said liquid and air is transported through pipe 7 to the hydro cyclone 8 where the liquid is separated from the air and collected.

Because the foam is transformed into a liquid when exposed to the lower pressure in pipe 7, it is not necessary to spray water into the hydro-cyclone to melt the foam, as is done in the commonly used skimmers where the foam is not broken down by being exposed to vacuum. This is a significant advantage when it is desirable to collect the compounds separated from the initial water flow since they are obtained in a significantly more concentrated form. Another advantage of the present invention is that it lowers both the cost of purifying the initial water flow, and the environmental impact of releasing the organic matter into the sewage drain. Further, the system has a very simple construction by not requiring any mechanical collection, or crushing/breaking, of the foam.

The system, process and use described above are advantageous in all processes where a separation and collection of dissolved and/or suspended organic matter from water is desired. More specifically it is highly advantageous when the organic matter to be separated has an intrinsic value by itself.

The system, process and use is especially advantageous when used in the separation and collection of enzymes and/or proteins present in the hatching liquid from fish egg hatcheries, even more specific from salmon egg hatcheries. In addition to the use in said fish egg hatcheries, use in other forms of marine species hatcheries and/or farming such as lobster, crabs etc., is contemplated.

The present invention can be used both in hatcheries having a "flow-through" system, as well as hatcheries were the water is recirculated. The system, process and use may also be further complemented by the use of for example pre-filtration or sedimentation for removing solids and, in the case of fish egg hatcheries, egg shell fragments from the water flow before entering the separation system. The organic matter, and more specifically the hatching liquid, may be further purified and isolated into separate compounds by combining the system or method above with a further purification step. This step may comprise for example gel separation and membrane filtration Definition of terms

As used in the description and in the appended claims, the term "protein skimmer" is meant to encompass any apparatus suitable for purification of water by the use of air bubbles with the object of obtaining foam enriched in organic matter from said water.

As used in the description and in the appended claims, the term "organic matter" is meant to encompass all types of organic chemical compounds and substances, including proteins, enzymes, polynucleotides and similar.

As used in the description and in the appended claims, the term "hatching liquid" is meant to describe the mixture of valuable proteins, enzymes and components thereof which is produced in the hatching of fish eggs.

As used in the description and in the appended claims, the term "vacuum" is meant to describe an air pressure that is lower than the atmospheric pressure.