AU760331B2 - Sewage treatment apparatus - Google Patents

Description

P:\OPER\RSI\2155438-spe.doc-13A)2A)3 -2- SEWAGE TREATMENT APPARATUS The present invention relates to sewage treatment apparatus.

A requirement exists for sewage treatment apparatus which does not require the use of added water or chemicals and which can therefore be used in remote areas where water is not readily available and where the use of chemicals may present a disposal problem.

There is disclosed in Australian patent specification 575176 and patent application 21656/95 sewage treatment apparatus which operates by a natural composting method.

The previously proposed sewage treatment apparatus comprises a rotatable unit having waste-receiving compartments rotatable to place successive compartments beneath an outlet from a toilet pan. Waste material builds up within the compartments with liquid from the waste draining into a tank. When the operative compartment is full of solid matter the unit is rotated to present the next compartment to receive waste from the toilet pan. Air is drawn continually across the liquid in the tank and through the compartments in order to evaporate the liquid and also to create a humid environment which assists in the aerobic decomposition of the solid matter within the compartments. Periodically each S •compartment requires to be emptied of solid composted matter.

oooo 20 Although the prior apparatus operates effectively, the rotatable waste-receiving unit is relatively expensive to produce and is also relatively bulky leading to relatively high transport costs.

The present invention relates to a rotatable waste-receiving unit for use in sewage treatment apparatus and which can be produced at substantially less cost and considerably less bulk and which may therefore be of advantage for supply to certain third world countries.

According to the present invention, there is provided a waste-receiving unit for use eoooo in sewage treatment apparatus, said unit comprising a rotary supporting frame mounted for rotation about a vertical axis, and means arranged around the frame for removably P:\OPERkRSHI2155438.p.d -3A2/03 -3supporting from the frame porous waste-receiving bags arranged around the axis of rotation, with the bags being suspended from the frame with the mouth of each bag facing upwardly and being held in an open configuration to receive human or animal waste material or other organic waste material when the turntable is rotated to place the open mouths of the successive bags beneath a waste outlet, the porous structure of the bags enabling liquid to drain from the bags and air to enter the bags to facilitate aerobic decomposition of the solid waste within the bag.

Advantageously, in a preferred embodiment of the invention the supporting frame provides a series of supporting compartments of segmental shape arranged around the axis of rotation such that each bag can be supported within a respective one of the compartments with its open mouth lying within the compartment and held to a segmental shape generally corresponding to that of the compartment.

Preferably, the bag is releasably retained to the compartment by support rods or a support frame removably supported by the sides of the compartment.

o Advantageously, each porous bag is supported within an outer bag which is .ooo separate from the inner porous bag but is also attached to the sides of the supporting compartment, the outer bag serving to support much of the weight of the inner porous bag when fuill.

The inner porous bag must be such as to enable entry of air into the bag and liquid to drain from the bag without permitting larger particles of solid matter to pass through the wall of the bag to possibly form a sludge in the zone beneath the unit. One particularly suitable form of fabric for use as the porous inner bag is a porous geo-textile fabric.

The present invention also provides a kit adapted for transportation for construction of a unit as defined above, said kit comprising said frame and said means for removably oo.ooi supporting the bags from the frame with the mouth of each bag facing upwardly and being S held in an open configuration.

P:\OPERRSHSEWAGET.CAP- 19/3/99 -4- The present invention also provides a rotary supporting frame for use as the frame in a unit as defined above, said frame comprising a vertical shaft, means for mounting the shaft for rotation about its axis, and support means carried by the shaft and arranged around the axis of the shaft, the support means being adapted to support a plurality of said bags in an annular array around the axis of the shaft with the mouth of each bag facing upwardly and being held in an open configuration.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic perspective view, partially cut-away, of a toilet building incorporating a waste-receiving unit in accordance with a preferred embodiment of the invention; Figure 2 is a schematic section, similar to Figure 1, and showing the unit installed within a lower enclosure of the building; Figure 3 is a side view of a turntable which forms a main structural component of the unit and which supports waste-receiving porous bags; Figure 4 is a plan view of the turntable; and Figure 5 is a schematic plan view illustrating one of the compartments of the turntable and bag support rods which co-operate with the sides of that compartment.

As shown in Figures 1 and 2 of the accompanying drawings, a waste-receiving unit for use in sewage treatment apparatus comprises a turntable 2 supported for rotation about a vertical axis 0 and carrying a series of waste-receiving containers in the form of removable porous bags 4. The tumrntable 2 and the bags 4 will be described in detail hereinafter. The turntable 2 is rotatable to place the successive bags 4 beneath the outlet of a toilet pan 6 or equivalent within an enclosure 8 above the turntable 2. The turntable 2 is mounted within a lower enclosure 10 having an inlet 12 for warm air which passes across and evaporates liquid which has drained from the bags 4 onto the base of the enclosure 10, with the warm moist air passing through and around the bags 4 to be discharged from the enclosure 10 via a vent pipe 14. The warm air is fed into the lower enclosure 10 from a heating enclosure 16 in which air is heated by solar effect and the heated air is thereby forced into the lower enclosure P:\OPER\RSH\SEWAGET.CAP -18/3/99 via the inlet 12. Although in the embodiment shown, the heating enclosure 16 is separate from the main enclosure 10, in an alternative construction there may only be a single enclosure in which the air is heated and the tumrntable 2 is mounted. The waste material within the bags 4 decomposes by aerobic decomposition in the manner described in the prior specifications previously discussed. The enclosures 8,10 for the toilet pan and turntable, and the heating enclosure 16 will be constructed on site, possibly using locally-sourced materials, to co-operate with the turntable 2 which forms the main functional component of the apparatus. The turntable will now be described in greater detail.

As shown in Figures 3 and 4, the turntable 2 comprises a vertical shaft 20 journalled oooee S" at its upper and lower ends in bearings carried by upper and lower plates 22 to be anchored to the base and upper wall of the lower enclosure 10, for example by bolting through the plate. The upper end of the rotatable shaft 20 carries a supporting frame in the form of a circular rim 24 and radial spokes 26 leading from the rim 24 to the shaft 20. The frame thus defines a series of supporting compartments 28 of segment shape arranged around the axis of the shaft 20. Each compartment 28 removably supports a porous inner bag 4 which hangs from the frame and an outer supporting bag (not shown) of a strong mesh material which also hangs from the frame and helps support the weight of the inner bag 4 when full and which may weigh up to 80 kilogram when the contents within the inner bag are wet. The open upper ends of the inner porous bag 4 and separate outer support bag are threaded onto removable support rods 30 (Figure 5) which hook onto, and extend along the two radial spokes 26 at each side of the compartment 28 and onto at least one support rod 32 which hooks onto the part of the outer rim 24 at the radially outer edge of the compartment, the support rod 32 being of arcuate shape to conform to the curvature of the outer edge of the compartment; to facilitate manipulation of the bags particularly for emptying, the support from the outer rim 24 can be effected by a plurality of shorter arcuate support rods 32 attached to the outer rim 24. By this means, the bags are fully supported from the frame of the turntable with their open ends held open in a configuration of segmental shape equivalent to that of the supporting compartments 28. The maintenance of the bag mouth in the open configuration in conjunction with the external support provided by the outer mesh bag enables P:\OPERXRSH\SEWAGET.CAP- 18/3/99 -6the inner bag 4 to be used to its full capacity before emptying is required.

Instead of using support rods 30, 32 to support the bags from the main supporting frame of the turntable 2, the open ends of each pair of inner and outer bags can be carried by a separate frame which hooks or otherwise removably mounts on the main supporting frame.

When a bag 4 is substantially full of decomposted waste material, it can be removed from the supporting frame by unhooking the support rods 30, 32 from the frame, unthreading the support rods from the top of the bag 4 and then closing the bag 4 possibly by means of 10 a drawstring around its top for subsequent disposal or emptying and re-use. Alternatively, .e.o.i by unhooking the arcuate support rods 32 from the rim and unhooking the outer ends of the radial support rods 30, the open end of the bag mouth can be tipped downwardly to permit emptying of the contents into another receptacle which can then be removed, with the support rods 30, 32 then being re-attached to the supporting frame to permit re-use of the bag.

The inner porous bag 4 must be of a construction which allows liquid to drain from the bag and air to enter the bag without allowing larger particles to fall through the bag and form a sludge in the bottom of the lower enclosure 10. On the other hand, the pore size of S•the inner bag must not be too fine otherwise clogging may occur. We have determined that a porous geo-textile fabric in the form of a non-woven synthetic needle-punched fabric with a pore size of about 175 microns provides effective results with the particular pore size providing a good flow rate of liquid and air across the wall of the bag. It is however to be understood that other materials may be suitable for the bag, for example certain types of hessian provided that the pore size is such as to preclude passage of particles of waste matter of a size which would form a sludge.

The turntable is relatively inexpensive to produce and is not of a large bulk whereby it can readily be transported without incurring substantial transportation costs. The inner porous bag and outer mesh supporting bag are also relatively inexpensive to produce and are lightweight and of low volume when packed for transportation. Although the bags will P:\OPER\RSH\SEWAGET.CAP- 18/3/99 -7usually be supplied with the turntable, when the turntable is shipped to third world countries the bags may be supplied locally using locally-sourced materials.

The embodiment has been described by way of example only and modifications are possible within the scope of the invention.

Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer 10 or group of integers.

*o o oO

Claims (9)

1. A waste-receiving unit for use in sewage treatment apparatus, said unit comprising a rotary supporting frame mounted for rotation about a vertical axis, and means arranged around the frame for removably supporting from the frame porous waste-receiving bags arranged around the axis of rotation, with the bags being suspended from the frame with the mouth of each bag facing upwardly and being held in an open configuration to receive human or animal waste material or other organic waste material when the turntable is rotated to place the open mouths of the successive bags beneath a waste outlet, the porous structure of the bags enabling liquid to drain from the bags and air to enter the bags to facilitate aerobic decomposition of the solid waste within the bag.

2. A unit according to claim 1, wherein the supporting frame provides a series of supporting compartments of segmental shape arranged around the axis of rotation such that each bag can be supported within a respective one of the compartments with its open mouth lying within the compartment and held to a segmental shape generally corresponding to that of the compartment. o e.

3. A unit according to claim 1 or claim 2, wherein each bag is releasably retained to the compartment by support rods or a support frame removably supported by the sides of the compartment.

4. A unit according to any one of claims 1 to 3, wherein each porous bag is supported within an outer bag which is separate from the porous bag but is also attached to the sides of the supporting compartment, the outer bag serving to support a substantial part of the weight of the porous bag when full.

A unit according to any one of claims 1 to 4, wherein the bag is formed from a porous geo-textile fabric.

6. A kit adapted for transportation for construction of a unit according to any one of P:\OPER\RSH\SEWAGET.CAP 23/3/99 -9- claims 1 to 5, said kit comprising said frame and said means for removably supporting the bags from the frame with the mouth of each bag facing upwardly and being held in an open configuration.

7. A kit according to claim 6, further comprising a plurality of said bags of a porous material enabling entry of air into the bag and liquid to drain from the bag without permitting larger particles of solid matter to pass through the wall of the bag to form a sludge.

8. A rotary supporting frame for use as the frame in a unit according to any one of claims 1 to 6, said frame comprising a vertical shaft, means for mounting the shaft for rotation about its axis, and support means carried by the shaft and arranged around the axis of the shaft, the support means being adapted to support a plurality of said bags in an annular array around the axis of the shaft with the mouth of each bag facing upwardly and being held in an open configuration.

9. A supporting frame according to claim 8, wherein the mounting means comprises bearings at an upper and lower end of the shaft, said bearings being carried by upper and lower mounting plates for anchorage to adjacent structure. A waste receiving unit substantially as hereinbefore described with reference to the accompanying drawings. DATED this 23rd day of March, 1999. ENVIRONMENT EQUIPMENT PTY.LTD. By its Patent Attorneys: DAVIES COLLISON CAVE