Patent Description:
When treating water to be returned to nature a treatment plant of some kind is typically employed. The treatment in a treatment plant can undergo multiple processes. In one step water to be treated can undergo a chemical treatment. In a step of chemical treatment a chemical substance is added to extract different substances, such as phosphates, from the water using a precipitation process. In precipitation of phosphorus a sludge is formed. The precipitated phosphorus sludge is then removed and is taken care of together with other sludge from the treatment plant.

<CIT> relates to a system and a method for treating wastewater using a passive phosphorous-capture filter lined with wood activated by the impregnation of a metal in the form of a hydroxide.

<CIT> relates to a phosphate ion solidification agent containing a multivalent metal ion enclosed and fixed in hydrophilic gel and a phosphate ion solidification apparatus containing the phosphate ion solidification agent being useful if it is used for a septic tank. The phosphate ion solidification apparatus may have a structure in which a column filled with the phosphate ion solidification agent is installed and target water containing phosphate ion to be treated is passed through the column, or in which a water-permeable container containing the phosphate ion solidification agent is immersed in an immersion tank and object water containing phosphate ion to be treated is passed through the immersion tank.

There is a desire to improve existing treatment processes and reduce the environmental impact caused by existing treatment processes.

It is an object of the present invention to solve the above problem or at least reduce the negative environmental impact caused by existing treatment processes.

This object is at least partly obtained by the invention as set out in the appended claims.

In accordance with one embodiment an apparatus for treatment of water according to claim <NUM> is provided. The apparatus for treatment of water may comprise a container.

Untreated water can be fed to the container.

When untreated water is fed to the apparatus together with a chemical compound typically a precipitation or flocking agent, chemical compounds in the untreated water such a phosphorus will be precipitated using the precipitation agent. The precipitated chemical compounds will bond to the small particles of the solid substance and small particles having precipitated chemical compounds bonded thereto will during ongoing aerating and under the force of gravity pass downwards through the layer and can be collected in the collection container provided under the layer. The chemical compound in the collection container can then be taken care of and is easy to re-use.

The present invention will now be described in more detail by way of non-limiting examples and with reference to the accompanying drawings, in which:.

In the following a water treatment apparatus will be described. In the figures, the same reference numerals designate identical or corresponding elements throughout the several figures. It will be appreciated that these figures are for illustration only and are not in any way restricting the scope of the invention that is defined in the appended claims. Also, it is possible to combine features from different described embodiments to meet specific implementation needs.

In <FIG> a side view and a sectional view along the section A- A of an apparatus <NUM> for treatment of water is shown. The apparatus <NUM> comprises a container <NUM> to which untreated water <NUM> can be fed via an inlet <NUM>. The flow of water through the apparatus <NUM> is generally shown by arrows in the figure. The container <NUM> can generally be divided into two compartments, a first compartment <NUM> for receiving untreated water and to treat water and a second compartment <NUM> provided down streams the first compartment <NUM>. An outlet <NUM> for treated water is in fluid connection with the second compartment via which outlet treated water exits the apparatus <NUM>. Between the first compartment <NUM> and the second compartment <NUM> a connecting part <NUM> can be provided that allows water to flow from the first compartment <NUM> to the second compartment <NUM>. Thus, in accordance with the present invention the first compartment <NUM> and the second compartment <NUM> are communicating vessels. In the container <NUM> an air permeable layer <NUM> is provided. The air permeable layer <NUM> separates the first compartment <NUM> from the second compartment <NUM> in the container <NUM>. In the embodiment of <FIG>, the container <NUM> is designed with an outer wall forming an outer wall and also inner separation wall separating the first compartment <NUM> from the second compartment <NUM>. Both the inner separation wall and the outer wall can have a generally circular cross section. Thus, in accordance with the embodiment of <FIG> untreated water <NUM> will first flow into an outer first compartment <NUM> of the container <NUM> having a generally annular cross section in which treatment is performed and then be fed to the inner second compartment <NUM> of the container <NUM> with a generally circular cross section from which treated water can leave the container. In the embodiment shown in <FIG>, the connection <NUM> is formed by a lower section of the container <NUM>. Other types of connections are possible such as a pipe connection. Water can also be pumped between different compartments of the apparatus <NUM>.

The air permeable layer <NUM> can wholly or partly be made of a polymer material or a fine meshed metal net having a suitable hole dimension. For example, the holes in the layer <NUM> can have a size in the range <NUM> -<NUM> micrometers, in particular <NUM> - <NUM> micrometers. In some applications the size of the holes can be bigger for example in the range <NUM> - <NUM>. In the container <NUM> there is bed of a solid substance <NUM> having suitable dimensions or a mix of different dimensions. The solid substance <NUM> can for example be a sand material or a clay material. For example, rock flour, a slag material or a Leca material can be used. The solid substance can advantageously have dimension in the range <NUM> - <NUM> micrometers. The solid substance <NUM> can also comprise particles with bigger dimensions that in use will split into particles with smaller particle sizes. For example, the solid substance <NUM> can when aerated have properties such that the particles of the solid substance will split into particles of smaller sizes at a suitable rate such that smaller particles of the solid substance <NUM> is continuously formed or is formed when the solid substance is aerated.

In accordance with one embodiment the solid substance <NUM> can be supplied during the treatment process performed in the apparatus <NUM> such that there is always a suitable amount of particles of the solid substance in the first compartment <NUM> that phosphorous compounds can bond to. The supply of the solid substance <NUM> can for example take place continuously or when untreated water is fed to the first compartment <NUM>.

The air permeable layer <NUM> is further designed so that the solid substance <NUM> rests on top of the air permeable layer and such that small particles of the solid substance pass through the layer <NUM> when air passes up through the layer as is described below. This can be said to be analogous to an aerated sand filter or a fluidized bed. A bed is provided in the first compartment <NUM> of the container <NUM>. The bed comprises a solid substance of small particles and the untreated water is located on top of the bed.

Under the air permeable layer <NUM> an aerating device <NUM> is located. The aerating device is provided to generate air under the air permeable layer <NUM> so that air will rise through the layer <NUM> and aerate the bed of solid substance particles <NUM> on top of the layer <NUM> and the water <NUM> inside the first compartment <NUM> of the container <NUM>. The layer <NUM> can, in accordance with one embodiment, be aerated under only a part, such as a central part, of the layer <NUM>. Under the layer <NUM> a collection container <NUM> is also located. In the example of <FIG>, the collection container <NUM> is formed by the bottom of the connection <NUM>. In other embodiments a separate collection container <NUM> can be provided. The collection container <NUM> can then be removable for emptying or exchange of the collection container <NUM>. The shape of the collection container <NUM> can in accordance with some embodiments be tapered for example conically tapered.

The apparatus <NUM> is provided with a feed device for feeding a precipitation agent or flocking agent. In accordance with one embodiment a flocking agent is added when treatment of water is performed. Examples of suitable flocking agents when water is to be purified from phosphorus are solutions comprising aluminium, iron or calcium. In accordance with some embodiments aluminium sulfate or aluminium chloride can be added in solid or liquid form. In accordance with some embodiments, suitable forms of iron chloride or calcium chloride is used.

In the apparatus <NUM> an emptying device <NUM> for removal of precipitated materials collected in the container <NUM> can also be provided. The emptying device <NUM> can for example be adapted to vacuum/suck solid materials from the container <NUM>.

In <FIG> another embodiment of the apparatus <NUM> is shown. In <FIG> the inlet is provided in the center of the container <NUM> and the outlet is connected to an outer section of the container <NUM>. Other possible embodiments include a configuration where the outlet <NUM> unlike in <FIG> and <FIG> is located at a higher level than the inlet <NUM>. Such an embodiments shown in Fig. <NUM>. It is also possible to arrange the inlet <NUM> and the outlet <NUM> at essentially the same level. In accordance with some embodiments the outlet <NUM> is located at a level above the layer <NUM> that is provided inside the apparatus <NUM>.

Further modifications of the apparatus are possible. For example, the container <NUM> does not necessarily need to be made as one single container but can instead be divided into two or more serially connected containers in communication with each other. For example, one or more of the parts <NUM>, <NUM>, <NUM> can be formed as separate containers connected to each other so that untreated water can be fed to the part <NUM> to then pass the part <NUM> before the water reaches the part <NUM>. In such a set-up a collector container <NUM> still needs to be provided below the layer <NUM> for collection of particles passing down through the layer <NUM>. Water can be transferred between the different part by pressure or in accordance with some embodiments by pumping.

In <FIG> a flowchart describing different steps performed in the apparatus <NUM> when treating water therein. First, in a step <NUM>, untreated water, for example comprising phosphates, is fed to the container <NUM> a treatment process is started. In the treatment process a chemical substance is added to the first compartment to extract a substance from the untreated water in a step <NUM> and the bed comprising a solid substance of small particles <NUM> is aerated through the layer <NUM>. The added chemical substance is a precipitation or flocking agent. The chemical substance will bond the phosphorus substance in the water and the chemical compounds then formed will bond onto the small particles of the solid substance in the bed <NUM> (or onto small particles added) that is aerated by the aerating device <NUM> in a step <NUM>.

Through the aerating process the small particles having a chemical compound comprising phosphorus will also be able to pass downwards through the layer under the force of gravity to the collection container <NUM> located thereunder. The small particles will then be collected in the collection container in a step <NUM>. As more untreated water is supplied water is pressed (or pumped) down streams through the apparatus to the second compartment <NUM> via the connection <NUM>. Water reaching the second compartment <NUM> is purified from e.g. phosphorus substances and treated water can leave the container <NUM> in a step <NUM>.

Thus, the collection container <NUM> collects very small particles (small enough to pass down through the layer when the layer is aerated) and these particles have chemical compounds comprising phosphorus bonded thereon (or whatever substance the apparatus is designed to purify the water from). The collection container <NUM> can then be emptied in a suitable manner. As set out above the emptying can be performed by vacuuming using the emptying device <NUM> or by removal/ exchange of the collection container <NUM>. The material in the container <NUM> will, in case phosphorus is removed from the water, comprise a chemical compound comprising phosphorus that is easy to recirculate. If, for example, aluminium is used in the flocking agent the solid material in the collection container <NUM> will comprise aluminium phosphate bonded to the small particles in the solid substance.

In accordance with one embodiment, aerating is only performed when untreated water is supplied to thereby reduce consumption of the solid substance in the bed <NUM>. Further, dosing of the flocking agent can be made in response to the current supply of untreated water. As set out above, the solid substance can also be dosed and continuously be added in the corresponding manner as the chemical substance, e.g. a flocking agent. Adding of the solid substance can be performed using a feeding device.

It is to be noted that the shape of the container can be any shape and does not need to be circular. For example, the container can be square or rectangular. Further the apparatus is suitable to purify water from different chemical compounds and not only phosphorus substances. For example, different metals such as copper and also cadmium can be removed from the water using the apparatus. The flocking agent used is then adapted to the chemical compound to be removed from the water by the apparatus.

Claim 1:
An apparatus (<NUM>) for treatment of water comprising a first compartment (<NUM>), wherein untreated water (<NUM>) together with a precipitation agent or flocking agent can be fed to the first compartment (<NUM>), the apparatus comprising:
- an inlet (<NUM>) for the untreated water (<NUM>), which inlet (<NUM>) leads to the first compartment (<NUM>), wherein the first compartment (<NUM>) is adapted to receive a solid substance,
- an air permeable layer (<NUM>) down streams the first compartment (<NUM>), wherein the air permeable layer (<NUM>) is configured such that small particles of the solid substance are able to pass through the air permeable layer (<NUM>) when air passes up through the air permeable layer (<NUM>),
- a bed of solid substance having small particles (<NUM>) received by the first compartment (<NUM>) on top of the air permeable layer (<NUM>),
- an aerating device (<NUM>) located beneath the air permeable layer and provided to generate air under the air permeable layer (<NUM>) so that, when the apparatus is in use, air will rise through the air permeable layer (<NUM>) and aerate the bed of solid substance (<NUM>) and water (<NUM>) inside the first compartment (<NUM>),
- a second compartment (<NUM>) located down streams said air-permeable layer, wherein the air permeable layer (<NUM>) separates the first compartment (<NUM>) from the second compartment (<NUM>), - a collection container (<NUM>) located beneath the air permeable layer (<NUM>) for collection of the small particles of the solid substance passing downwards through the air permeable layer (<NUM>) during aerating,
- an outlet (<NUM>) for treated water (<NUM>) from the second compartment (<NUM>),
- a feed device for feeding the precipitation agent or flocking agent to the first compartment, and
- a feeding device for feeding the solid substance to the first compartment (<NUM>).