Gas separation: processes – Solid sorption
Reexamination Certificate
2001-12-27
2003-10-28
Smith, Duane (Department: 1724)
Gas separation: processes
Solid sorption
C095S141000, C095S274000, C422S120000
Reexamination Certificate
active
06638338
ABSTRACT:
The invention relates to a biological filter system for cleaning air and a housing for a biological filter system. Moreover the invention relates to a method of cleaning and conditioning air.
The invention is based on the knowledge that soil, which contains microorganisms and serves as a substrate for plants, has a capacity to clean air and remove harmful particles and gasses from the air. This knowledge has been published by NASA and is a result of NASA research.
The recognition of such qualities of soil and plants has led to the use of soil and plants in pollution control. The advantage is that such pollution control is extremely friendly to the environment.
In recent years use of soil and plants in pollution control has gained commercial and practical interest and has become more and more common.
DE 195 21 239 A 1 discloses a bioactive filter for rooms. The filter comprises a housing wherein an inner container with filter material is placed. The filter material consists of porous material with high absorption capacity. Filter material can be open-pored different clay granules, humus, colloids, active charcoal, compost, specific chemical binders, limestone, magnesium oxide, calcite, etc. in different mixtures. Filter material can either have a general absorption to particles and chemicals or specific absorption, biological or chemical binding to specific gas compounds. The filter media allow plants with earth root balls to be planted. The air is driven through the filter by means of a fan. The filter provides good cleaning of the air, but does not stop germ cells and does not contribute to the general conditioning of the climate in the room.
The drawback of the known biological filters is that they do not stop germ cells from entering a location with the cleaned air. The germ cells may for instance enter the air from the soil that the air passes through.
One object of the present invention is to provide a filter system that will stop germ cells and other particles in the air effectively during the cleaning process.
Another object of the present invention is to provide a filter system that will de-gas and break down harmful gasses in the air effectively during the cleaning process.
A further object of the present invention is to provide a filter system that will contribute to the air-conditioning in a room with regard to temperature and relative humidity.
Moreover it is an object of the present invention to provide a self-irrigation system of soil and plants from a water reservoir.
These objects and other objects are met by the invention as defined in the claims.
The invention provides a biological filter system and a method for cleaning and conditioning air which are environmentally friendly and which result in a significant reduction of particles and harmful gases in the air.
The biological filter can be produced in various sizes and has an appearance like flowerpots, boxes, partition walls, or ground plants. The invention is thereby able to contribute to the decoration of a room or landscape and simultaneously clean and condition the air in the room or landscape.
In a first aspect the invention relates to a biological filter system for cleaning air comprising
a reservoir for water,
a layer of soil, and
a germ-reducing layer.
The biological filter is a part of a closed system, which the air is passed through as will be explained later.
The purpose of the reservoir for water is to moisten air and wet the layer of soil. The layer of soil holds back particles and gasses and optionally breaks down those particles and gasses in microbiologically processes in the soil, thereby cleaning the air passing through it.
The purpose of the germ-reducing layer is of course to reduce the number of germ cells in the air. The germ cells may be germ cells of bacteria and fungi that may enter the air from the soil. Furthermore the purpose of the germ-reducing layer is to prevent growth of bacteria and fungi at least in the surface of the soil, preferably at least into a depth of 2 mm of the soil.
In a preferred embodiment of the invention the biological filter system further comprises a compressor room.
In another preferred embodiment of the biological filter system of the invention the germ-reducing layer comprises material, which kills or destroys germ cells of bacteria and fungi.
Such material can be chosen among material having a high or low pH value or basic or acidic material. Useful basic material preferably has a pH>10 and useful acidic material preferably has a pH<4. Other useful materials have a pH of about 7-9.
Preferably the material is selected from the group consisting of limestone, dolomite, calcite, magnesite, celluloses, hemicelluloses, woodchips and a combination thereof
The exact mechanism of the disinfective effect of the germ-reducing layer is not known. The disinfection may be caused by the influence of ions, such as Mg- or Ca-ions, but the invention is not limited to this theory.
Besides killing and destroying germ cells the germ-reducing layer may also act as a mechanical filter for particles and is preferably also capable of absorbing various particles.
Preferably the material constituting the germ-reducing layer has an average particle size from 0.1 to 7.0 cm measured by sieving.
Preferably the thickness of the germ-reducing layer is from 0.1 to 10 cm, more preferred from 0.5 to 6 cm.
In another preferred embodiment of the biological filter system according to the invention the reservoir for water is placed directly in or below the layer of soil, with air pockets or a distance between the surface of the water and the bottom of the layer of soil, said volume or distance being sufficient to allow a flow of air in the soil or between the surface of the water in the reservoir and the bottom of the layer of soil, preferably said distance is within the range of 0.1 to 15 cm.
Hereby it is possible for the air to pass over the water in the reservoir and collect moisture and immediately after enter the layer of soil. A porous bottom plate, e.g. a metal plate with holes, preferably supports the layer of soil. The distance between the surface of the water and the bottom of the layer of soil will, of course, vary with the amount of water present in the reservoir.
Furthermore the reservoir for water may be connected to the layer of soil, preferably by use of one or more wicks. The wicks will draw water from the reservoir up into the layer of soil and thereby wet the soil and optionally the roots of plants present in the soil. When the layer of soil is supported by at bottom plate this may by coated with a porous cloth which is connected to the wicks and will help wetting the soil. This preferred embodiment facilitates self-irrigation of soil and plants.
Preferably the biological filter system according to the invention comprises means for forcing the air through the filter-system. The means comprises an inlet for air to be cleaned and substantially airtight chambers where pressure can be created to force the air through the biological filter system. The pressure can be created by use of a fan, ventilator, or the like.
In yet a preferred embodiment of the biological filter system according to the invention the layer of soil comprises humus and/or clay with microbiologic activity. The microbiological activity appears naturally in humus and is caused by bacteria and other microorganisms naturally present in humus, clay and soil. The layer of soil may also comprise expanded clay or other porous material in order to make the soil sufficiently porous to allow a flow of air to pass through it.
Preferably the layer of soil has a porosity which allows a flow of air through said layer of soil of 200-500 m
3
/m
2
h, more preferred 300-400 m
3
/m
2
h.
The layer of soil preferably has a thickness from 5 to 80 cm, more preferred a thickness of 15 to 50 cm.
In another preferred embodiment the layer of soil constitutes the substrate for one or more plants. The substrate serves as a growth media for a wide range of plants, which in combination with the layer of soil contributes to the pro
Lawrence Frank M.
Smith Duane
LandOfFree
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