Chemistry: molecular biology and microbiology – Apparatus – Bioreactor
Reexamination Certificate
2000-12-22
2003-02-11
Redding, David A. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Bioreactor
C435S290400
Reexamination Certificate
active
06518057
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a composting device and an aerator for use in a receptacle for composting material.
It is becoming a common practice for households to recycle domestic rubbish. One method of recycling is to place organic material, such as food scraps and vegetative matter, in a compost bin, allow the material to decompose and then use the composted material as a fertilizer. A typical compost bin has rigid side walls, an open bottom and top. The bin is placed on the ground so that the ground forms the base of the container. A closure is often provided for the opening.
Unfortunately, the rate of decomposition of material placed in such a bin can be slow as the supply of air to the composting material is often inadequate, especially if the opening to the container is closed with the lid. A free flow of oxygen is essential to support aerobic activity by composting bacteria.
A by-product of decomposition is a fluid called leachate. The present applicant has recognised that 9 this fluid remains in the composting material during the composting process it can interfere with the composting process as it can slow the flow of oxygen in the material. In the type of bins mentioned above it is not possible to easily separate the leachate from the decomposing material, and this is a further difficulty with such bins.
The present application seeks to overcome or ameliorate these problems
BRIEF SUMMARY OF THE INVENTION
According to a first aspect, the present invention is directed to a composting device including:
a receptacle having an opening and an internal space;
load supporting means located inside said receptacle to support material placed therein away from the lower end of the receptacle and to define a fluid collection chamber at said lower end, said fluid collection chamber being in fluid communication with a portion of the internal space above the load supporting means;
one or more aerators located within said receptacle, each aerator having a body having an internal air chamber and one or more apertures to permit air in said air chamber to pass out through said aerator and into said receptacle; and
an air inlet opening into said receptacle and in gaseous communication with said aerator to permit air outside said receptacle to enter said aerator.
The receptacle may be a simple bag. Alternatively, it may be a container having a base, rigid walls and a closure for the opening of the container. A type of container useful in this invention has a pair of wheels located at its lower end and a handle at its upper end so that the container can be tipped onto its wheels and moved around.
Such a wheel container is commonly referred to as a “wheelie bin”.
Preferably, the load supporting means has an opening and the aerator connects with said opening. For example, the lower end of the aerator may extend into the opening so that there is a contact fit between these two structures.
In this manner the load supporting means also functions to hold the aerator in position, which is preferably in the centre of the receptacle. Where the lower end of the aerator extends through an opening in the load supporting means, a locking nut may be fitted to the lower end to secure the aerator in place.
The lower end of the aerator may have an opening to the internal air chamber aerator. It is also preferably that the upper end of the aerator is closed so as to prevent the entry of composting material into the aerator. However, one or more apertures may be located in the upper end to allow airflow through the upper end.
Preferably the aerator has an elongate shape and is located so that it extends upwards through the centre of the receptacle. It is preferred that the aerator in the receptacle be completely covered by decomposing material so as to minimise heat loss through the aerator. Where the aerator takes the form of a column extending up through the receptacle, and there is insufficient material in the receptacle to completely cover this column, an upper pad of the column, an upper part of the column will be exposed. Accordingly, in a preferred embodiment there is provided a cap for fitting over the upper end of the aerator to minimise the flow of air through the upper end of the aerator.
When the material in the receptacle starts to decompose, heat is generated. The heat causes convection currents in the aerator, which assists in drawing air from outside the receptacle and into the aerator.
In one embodiment a mesh material, such as wire mesh, is used to form the aerator.
In another embodiment, the aerator is formed from one or more interconnecting units, each unit including:
an upper end, a lower end, an internal air chamber and an opening at each upper and lower ends to said air chamber;
one or more projections extending outward from a side of said unit for contacting material failing onto said unit; and
one or more apertures to permit air inside said air chamber to pass through said aerator.
In another aspect, the present invention is directed to such an aerator per se for use in a composting device.
The one or more projections contact compost material falling onto said unit to minimise the build-up of this material around the unit,. Preferably these projections are angled so that they extend downward and outward from the unit and thereby act to deflect material away from the unit. In a further preferred embodiment these deflecting projections are located at or adjacent the upper end of the unit. There may be present only one such angled projection on each unit, which extends around the unit to form a collar. Alternatively, a series of arms may be located around the unit, each arm extending downwardly and outwardly from the upper end of the unit to provide a number of angled surfaces. The arms may form a star or cross pattern when viewed from above. Three to six arms are preferably present. Preferably, the angled surface or surfaces extend to 50 to 100 mm out from the side of the unit.
The outwardly extending projections assist in minimising the compaction of material around each unit as an air gap may form below each projection.
It is preferred that the one or more apertures are located beneath the outwardly extending projections so as to minimise the possibility that downwardly failing material enters the aerator through the apertures. For example, the apertures may be located in the side of the body of the unit. Alternatively, the apertures may be located in the underside of each projection.
The interconnecting units are preferably shaped so that the lower end of one unit can be placed in the upper end of an adjacent unit to provide a contact fit. In this manner, a number of units may be fitted together to form a vertical column. This vertical column will have a series of outwardly extending projections and apertures evenly spaced along its length. This allows a good flow of air into the composting material at appropriate points to optimise aerobic composting and minimises the compaction of composting material.
It is preferred that decomposing material in the receptacle not be able to enter the aerator. Accordingly, where the aerator is formed from interconnecting units as described above, a closure may be provided to close the upper end of the uppermost interconnecting unit. Alternatively, the uppermost unit may differ from the lower units by having an upper end that is closed.
Preferably, the interconnecting units are made from plastics material.
The load supporting. means may be a plate. The surface of the plate may be flat or slightly curved so that leachate from decomposing material that contacts the surface is directed to the perimeter of the plate and then to the fluid collection chamber below. One or more support members may be provided to hold the plate in an elevated position. The function of the plate is to form a platform in the receptacle and create a fluid collection area below. This can be achieved by a load supporting means having different configurations. For example, in another embodiment the load supporting means has a hollow body hav
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