AU652879B2 - Method and apparatus for disposal and treatment of waste - Google Patents

Description

I -r 1 "METHOD AND APPA~ATUS FOR DISPOSAL AND TREATMENT OF WASTE" This invention relates to a method of and apparatus for disposal and treatment of waste. Thiis application is associated with my earlier Australian Provisional Patent Application No. PL0259.

This invention has particular but not exclusive application to a composting toilet, and for illustrative purposes, reference will be made to such an application.

However, it is to be understood that this invention could be used in other applications such as production of compost and/or disposal of waste in industrial, commercial and other situations.

With increasing population pressures and demands for a higher standard of living, disposal of human, domestic and .eee•i 15 industrial waste is an increasing problem. Apart from the eee• disposal of such wastes which is a problem in itself, there is *a considerable wastage of resources in simply discarding such wastes without recovering useful components or making useful products from the waste material.

Concurrent with the problems above is the increasing urban sprawl which requires an ever-extending sewerage network for the disposal of sewage waste. Installations for personal comfort and ablutions in remote areas such as national parks or roadside rest areas are usually septic systems which may contaminate local ground water and/or local watercourses.

Hitherto, composting toilets have been used which receive 2 human and other waste and by the use of microbial and larger organisms, convert the waste into a friable odour-free compost in a chamber or chambers provided beneath the toilet.

In one type of composting toilet presently in use, the chamber has a sloping base and receives the waste from a pedestal or such like at the floor level above the chamber. The sloping base has bars in the form of a grid or the like adjacent but spaced from the sloping base to provide a ventilation opening, and access hatches for access to the gompost are near the lower end of the sloping base.

This technology suffers from the problem that the height of the pile of waste often reaches to a close proximity to the bottom of the pedestal, thereby preventing the waste from being properly ventilated. Furthermore, unless the moisture content is within narrow limits, a moisture build-up may occur which may lead to solids flow falling outside the specification required for proper operation of such apparatus.

Furthermore, compost may fall down to the bottom of the sloping base and block the ventilation opening thereby causing ooo* 20 anaerobic decomposition of the waste in the toilet and the ooooo production of unpleasant odours.

A further disadvantage is that this type of composting toilet requires installation on sloping ground, or for the floor level of the toilet to be raised considerably above the level of 25 a flat ground surface, or for access to the lower level of the chamber to be provided. Where the toilet is installed on a :'slope, there is a tendency for the installation slope, there J~s a tendency for the installation to slide down the slope. Because of the slope of the pile it is possible for freshly added wastes to roll down to the base of the pile and mix with the older compost and present a potential health hazard. Another disadvantage of this system is that a drain is provided at the lower end of the sloping floor for the discharge of any excess moisture. This water discharge is often high in coliform and/or indicator organisms and such like and so such technology is unsuitable for installation where there is a high water table or near a water course or the like.

In an alternative system, the toilet is placed above a series of bins which rotate under the floor, each bin in turn being placed under a pedestal. Such an apparatus requires a large floor area underneath the pedestal and a mechanical S 15 system to rotate the bins.

In yet another system, a small chamber is provided beneath the toilet which is stirred by a paddle on a horizontal Saxle. The temperaturej moisture content, stirring rate and other parameters must be monitored closely for this apparatus 20 to operate effectively. The close monitoring of this system is oooJ S required because of the small volume of the comnposting chamber, Moreover, since this system uses direct heating there is a

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potential for the apparatus to catch fire.

Many of the above described prior art systems have been e..

25 banned by health authoritiei due to their unreliability and health risk.

The present invention aims to alleviate one or more of 4 the above disadvantages and to provide a method of, and apparatus for the treatment of waste material which will be reliable and efficient in use.

With the foregoing in view, this invention in one aspect resides broadly in organic waste treatment apparatus for treating organic waste continually introduced thereto and including:a treatment chamber through which the organic waste material may pass in substantially plug flow; a compost outlet associated with the leading portion of the plug flow and through which treated material may be removed from said treatment chamber; an inlet through which organic waste material may be introduced into said treatment chamber to the trailing portion S 15 of the plug flow, and ioi aeration means for aerating waste material resident in said treatment chamber and including an air permeable wall at S" least partially supporting the leading part of said plug flow.

The treatment chamber may be arranged to provide for 20 extraction of substantially all treated waste after treatment S has been effected. Preferably, however, at least some of the treated waste remains in the treatment chamber indefinitely as inactive treated waste. Preferably the waste is treated by biological agents and/or activity and the inactive treated 25 waste provides a buffer zone whereby the living organisms may reside and/or rest. Without relying on theory or limiti.ng the scope of this invention thereto, it is believed that the buffer zone may be utilized by mobile organisms for refuge should the environmental conditions in the remainder of the waste material in the holding tank become unfavourable and/or the buffer zone may provide an inoculum means for the remainder of the waste material in the holding tank whereby microorganisms may be introduced into the remainder of the waste material under a range of operating conditions.

In a preferred embodiment, the invention in one aspect resides broadly in a composting apparatus for producing compost from waste, said composting apparatus including:a composting chamber for producing compost from waste wherein the waste being composted inside the chamber is supported above the base of the chamber and aerated by aeration means and wherein at least some of the waste being composted is S: 15 relatively inactive. Preferably, the composting chamber is defined by a composting container having a base wall, a side wall extending upwardly therefrom and a lid, and includes an .0 S" inlet, a solids outlet and a vent. Suitably, the comiposting chamber includes a compost support grid adjacent and spaced apart from said base wall. In a further preferred form, the support grid contacts the base at or near the centre and is spaced from the base around the perimeter. The inlet is for receiving the waste to be composted and the solids outlet is for extracting compost. The vent may be used to provide a .25 ventilation to the container, but preferably, the vent is used to provide a forced ventilation exhaust from the container.

The inlet, solids outlet and vent may be located at any 6 convenient position with respect to the chamber, however, in one preferred form, the inlet, outlet and vent are located in or pass through the lid whereby the base wall and side wall have no openings. In a further preferred form, the outlet is located in a side wall and sealed to the chamber. Suitably, such a preferred arrangement reduces the possibility of leakage into or out of the chamber so that the composting apparatus of this invention may be sited in areas having a high water table and/or in proximity to a water course. The volume of the compost chamber is preferably sufficient to give the waste material in the composting chamber a residence time sufficient for the decomposition thereof by microbial and biological means to produce compost.

The soils outlet may be an opening for the extraction of compost via manual, mechanical and/or automatic means. In a preferred form, the solids outlet includes an extraction tube which penetrates to the base of the compost heap and is adapted "to admit an auger, ,imble, scoop, ladle, or other extractor for compost removal. In a further preferred form, the solids 20 outlet is releasably resealable whereby the solids outlet may be sealed when not being used to extract compost and the auger is in the form of a trephine or such like.

In a preferred embodiment, the composting apparatus is in the form of a composting toilet including:- 25 a toilet pedestal which also functions as a waste entry chute; a compost chamber as hereinbefore defined, and 7 a ventilation means which draws air from the waste entry chute through the compost chamber. A solar, battery and/or mains powered fan may be utilised for the ventilation means but preferably the ventilation means is adapted to run coutinuously. Where the toilet pedestal is located inside a building such as a dwelling, the vent preferably exhausts to the outside of the building.

The composting toilet may be considered as an enclosed compost heap, kept well drained by a porous supporting partition in the bottom of the chamber which allows air to be drawn under the compost supplying oxygen and evaporating off any excess moisture from the compost chamber floor. Suitably, compost should contact the base of the compost chamber over an area in the centre of the base to allow contact with any excess 15 moisture which may accumulate in the base of the compost chamber. Compost contacting the base may by a wicking action absorb excess moisture. The conical shape of the base also 4O *S tends to direct moisture filtering down through the compost bed towards the centre of the base.

20 The composting toilet is preferably partially filled with ox** active compost at the time of installation and, inoculated with beneficial soil organisms and/or litter organisms. This varied mix of organisms includes microbiological organisms such as bacteria, moulds and fungi, as well as examples of larger 25 organisms such as worms, insects and other arthropods and such like. This biological action preferably reduces the waste to an odorless friab5 compost, rich in nutrients and safe to 8 handle. Flies and other undesirable vectors of disease are excluded from the organic matter by filters located in the ventilation system and by excluding them from access to waste being input to the compost chamber. Substantially no flies enter through the toilet pedestal since there is no odour trail to attract them. A fly trap may also be provided which attracts insects by a bright light source which encloses the insects until they die and fall back into the compost.

This invention resides broadly in another aspect on a method of producing compost and/or disposal of waste, said method including the steps of:providing a composting apparatus as hereinbefore defined having an inlet, a solids outlet and a vent to a composting chamber and a compost support grid adjacent and spaced apart ;rom a base wall within said composting chamber; supplying the composting apparatus with waste material at a rate sufficient to sustain composting of the waste material; providing forced ventilation to the composting apparatus by exhausting air from the composting chamber remote the inlet, 20 and extracting compost so formed at a rate sufficient to maintain a substantially constant quantitiy of compost within the composting chamber. The waste being composted may be arranged so that each part is extracted subsequent to the 25 conversion from waste material to compost, but preferably, the composting chamber includes a rest zone within which there is no substantial movement of waste material and/or compost, 9 whereby the zone is inactive insofar as the conversion of waste material into coiilpost. It is believed that the provision of a relatively inactive zone within the composting apparatus will render the operation of the composting apparatus of the invention more reliable.

This invention enables a composting toilet to be provided for the biological breakdown of domestic organic wastes such as sewage, kitchen scraps, waste paper, cardboard and the like in a relatively low cost hygienic system. This invention further enables a composting toilet to be provided which may require substantially no additional water, produce substantially no environmental contamination and require minimal maintenance.

Limited only to areas where frequent flooding above floor level is not likely to occur, the composting toilet of this invention S 15 may be adapted to all building types ai2 most climates.

*o In use, the invention may provide a composting toilet wherein there is substantially no user contact with fresh waste and wherein easy recovery of pathogen free garden fertilizer is provided. Without limiting the scope of this invention 20 thereto, living compost may be produced without odour and inconvenience, and moreover provides ease of recycling.

In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a typical 25 embodiment of the invention and wherein:- *too FIG. 1 is a sectional view of a waste disposal and treatment apparatus according to a preferred embodiment of this invention.

Referring to FIG. i, a waste disposal apparatus includes a treatment chamber 12 within the walls of a treatment vessel 11 which is circular in plan. The base floor 13 is sloped downwardly towards the centre and supports a permeable waste supporting wall 14 sloping downwardly from the perimeter to a central portion 15 which permits some of the compost to contact the base floor 13 over an area in the centze of the base to allow contact with any excess moisture which may accumulate in the base of the compost chamber. Compost contacting the base floor 13 may by a wicking action absorb excess moisture, and the base floor 13 is sloped downward to the central core 15 so that moisture accumulates preferentially toward the central core 15. The treatment vessel 11 also 15 includes a roof section 16.

The roof section is penetrated by an inlet chute 20, an *ses extraction tube 30 and a vent shaft 40. The inlet chute 20 is operatively connected to a toilet pedestal 21 having a toilet seat 22. It will be appreciated that alternative furnishings 20 may be provided for the comfort of the user such as a squat plate or the like, but a glazed ceramic pedestal is most frequently preferred. The inlet chute 20 and treatment vessel 11 are installed below the floor 51 of a building in the arrangement shown in FIG. 1. The pedestal 21 is sited within a oe ooeo 0 25 the walls 50 of the building and the vent shaft 40 is sited outside the walls 50 of the building.

The vent shaft 40 is operatively connected to a 11 ventilation fan 41 which provides forced ventilation from the treatment chamber 12 through the vent shaft 40 to a vent stack 42 which, in an alternative version, may have a wind vane 44 for rotating a vent outlet 43 so that the vent outlet 43 faces substantially leeward of any prevailing wind. The ventilation fan 41 may be of a sufficient draught to permit substantial ventilation of the room in which the pedestal is located.

The vent shaft 40 receives air from a ventilation chamber 52 beneath the waste supporting wall 14. The ventilation chamber in turn receives air from a compost by-pass shaft 53 extenting from the ventilation chamber 52 to adjacent *he roof section 16.

The waste material being treated in the treatment vessel 11 is maintained between a minimum level 54 and a maximum level 15 55, and the treatment chamber 12 holds a portion of the waste 4, e (I material in a dormant section 56 as shown.

Waste material deposited through the inlet chute 20 is treated in the treatment chamber 12 within the treatment vessel 11 by biological action such as composting. Once composting 20 has been effected in the treatment chamber, 12, an extraction auger 31 may be inserted into the treatment chamber 12 through the extraction tube 30 and rotating the auger 31 with the 9 eo.. handle 33 on the upper end of the auger 31 whereby compost may be retained in a receiving portion 34 in the lower end of the ee 25 auger 31. The lower end of the extraction tube 30 is shaped to facilitate the extraction of compost with the auger 31 as herein described.

12 In order that this invention may be more readily understood and put into practical effect, reference will now be made to the use of a preferred embodiment of this invention in the form of a composting toilet which may be installed in a building such as a house or cottage. Kitchen scraps, waste paper and cardboard are added to the compost pile through the toilet chute. Whilst not being bound by theory or limiting the scope of this invention thereto, it is believed that it is essential to add some absorbent material such as waste paper, cardboard, wood-shavings or saw-dust each week. Preferably it has been found that between 0.5 and 1 kg of absorbent matter is added each week for each person using the composting toilet if high quality compost is to be produced.

After two or three years the oldest compost at the bottom 15 of the chamber would be completely decomposed and quite safe to be extracted by removing the cap on the extraction tube and rotating the hand operated compost auger into the compost. The auger is then drawn out of the tube and the compost tapped into a bucket or wheel barrow. This procedure would be repeated 20 several times until between 10 and 20 liters of compost have been extracted. The compost may then be incorporated into a garden or such like to enhance its fertility.

For efficient operation of a composting apparatus according to this invention, it is suggested that absorbent 25 material may be added each week such as waste paper, cardboard, wood-shavings, saw-dust and/or the like as well as kitchen scraps. Larger items such as bones, pumpkins, melons, and the like may be reduced in size, paper and cardboard may be crumpled up and/or torn into hand sized pieces before adding to the composting apparatus.

The entry chute may be cleaned as needed with soapy water. Items such as tampons, sanitary pads, unwanted products made of wool, cotton or other natural fibers may be disposed of separately although they are usually suitable for composting.

It will be appreciated that disinfectant should not be used to clean the entry chute and should not be disposed of into the apparatus. Likewise, plastics, metals, cans, batteries, chemicals, antibiotics, mineral oils, paints, strong detergents, synthetic cloths or disposable nappies and such like would not be suitable for disposal in the apparatus.

In order to maintain the composting toilet in efficient 15 operation, some routine maintenance may be carried out such as cleaning the filters. For example, the preferred form of the composting toilet includes fine mesh filters located on each side of the fan which would require washing out with soapy water approximately every three months. A course mesh filter 20 (such as fly screen) located in the wind vane ventilator would for example require cleaning approximately every five years.

Some parts would be replaceable in the preferred embodiment, such as a battery for operating the fan.

Preferably, the battery is of the deep cycle lead acid type 25 having low maintenance. The expected life of the battery is approximately five years and my be replaced by unplugging the spent one and replacing it with a fresh one.

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:..00 08000 14 The ventilator fan is preferably a 12 volt, 100 nrm axial fan with a brushless DC motor, preferably operated through a controller system which automatically increases fan speed as required to evaporate off excess moisture. A condensation dripper 45 is provided at the base of the vent stack on the exhaust side of the fan to prevent condensation from damaging the fan or flowing back into the base of the compost chamber.

In order that this invention may be more readily understood and put into practical effect, reference will be made to the following trouble shooting schedule represented in Table 1 below:- TABLE 1 PROBLEM LIKELY CAUSE ACTION REQUIRED Odour in bathroom Fine mesh filters Clean filters adhere to or toilet blocked regular maintenance Fan not operating Check fan wiring connection Fan operating and Excess moisture Contact the supplier.

filters are clean indicator light is Increase the amount but odor still not working and of absorptive detectable more that 150 material to litres has compensate for the accumulated in the excess moisture.

base of the Excess moisture may chamber and have to bo pumped blocked the air out.

flow.

Excess water has Reduce the amount of been added down water added down the inlet chute. chute.

Increase the amount of absorptive material to compensate for the excess moisture.

Fan connected but Mains power failure. Check existence of mains not operating. power.

i TABLE 1 (cont'd)

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C. 'C.'r Fan connected but 12 V transformer not Test transformer and fan not operating. functioning or fan may and replace if necessary.

need replacing.

Fan connected but Water may be entering Check wind vane not operating. the vent stack. ventilator has not been accidentally removed or the condensation outlet is not blocked.

Battery connected Battery needs Check and replace the to solar panel but replacing battery if necessary.

flat Solar panel is not Reposition the solar receiving enough panel to receive the light, maximum possible sunlight.

Solar panel is not Check operation of functioning. the solar panel.

Compost pile has Excessive compost. Extract sufficient built up to the compost to drop the chute base. level.

Insects emerging Insects hatching from Disconnect fan for one through chute into compost hour and spray a low bathroom or toilet toxicity insecticide down when seat 1s the chute for ten to opened. fifteen seconds and shut the lid.

Compost dry and Too much absorbent Add extra water until not properly material or not enough compost activity is decomposed. moisture. restored. When tested with the auger there should be active tiger worms in each auger full.

If not, then re-introduce some through the extraction tube.

Compost which has Not enough absorbent Add more paper, cardboard been removed from material, wood-shavings etc. Add the tank has an more tiger-worms.

odour.

A composting toilet according to this invention may be installed in either ground level or elevated buildings. For example, in an existing elevated building, after selecting a 16 suitable location having no structural or supporting members, an opening for the pedestal may be marked and drilled or cut and an inlet chute installed in the opening, preferably 6s a clean interference fit. With the chute in position, and after levelling the ground beneath and provision of a level supporting pad, the tank may be moved into position. Preferably, clearancF between the floor timbers and the level pad is provided. In a preferred embodiment, the clearance is 1800 mm, and the pad is 1800 mm in diameter. The tank is then moved into position under the chute and centered under the chute with the extraction tube opposite the chute in an off centered arrangement. The chute is preferably made perpendicular to the tank and a lid installed after having the appropriate openings made for the chute, vent and compost extraction tube. Preferably the chute is installed 15 into the lid with an interference fit and fixed to the floor i above the tank with fastenings such as screws. Any excess length of chute may be cut off.

The chute may be sealed with a sealant such as mould resistant silicone around floor and tank openings. The pedestal may be installed by positioning and fixing with stainless screws.

Of course, a toilet seat may be installed as desired.

A vent stack is mounted preferably having a clearance above the roof ridge line. Of course, if the vent stack penetrates roof tiles, flashing and/or sealant may be used. A wind vane ventilator is preferably installed at the top of the vent stack and a fan preferably in the vent installed and connected to a power supply such as a 12 volt transformer operating off the mains supply or a solar panel. The vent stack may be braced if necessary.

For installing in a new ground level building, a suitable excavation is made below the desired toilet position and a tank installed in the appropriate location in the excavation.

Preferably, bearing pads, footings and/or such like are provided as appropriate. Support piers would be supported by corresponding bearing pads and the tank is also preferably anchored in position ready for back-filling the excavation. A beam is preferably placed between the support piers and the excavation back-filled around the extraction tube.

The ground floor of the building is then completed in the :4 normal manner, after which the pedestal is positioned and fixed.

A wind vane ventilator is fixed to top of the vent stack and the 41• 15 fan connected to the ventilation stack which is secured by saddle clamps. For solar powered extraction fans, a solar power supply may be installed. Of course, the vent stack is braced as necessary. The composting toilet may be started with a suitable volume of compost which may be put in place through the entry 20 chute.

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In a preferred embodiment, the volume of the chamber is 3.4 cubic metres which is sufficient to provide the long retention time required for complete decomposition, of the waste to stable humic colloids, typically three to five years. The chamber may be completely or partially buried depending on the building site and construction technique.

The compost is supported by a porous structural foam 18 polypropylene support partition and support ribbing. Excess water may percolate through this support and may accumulate up to the base of the ventilation tube. A water tight chamber enables the unit to be installed in high water table situations and sites where no environmentally hazardous discharge is desirable. A build up of water in the bottom of large volume composting toilets is alleviated by the product of this invention, In the composting toilet it is believed that the buffer zone provides a stabilising influence on the water material balance within the chamber. Organic colloids hold a large amount of water against gravity and allow excess water to percolate through. This excess is evaporated off by the forced ventilation layout as above.

In use, finished compost from a typical composting toilet *to* 0 15 of this invention is removed by rotating a hand operated extraction auger within the extraction tube. The auger and extraction tube are preferably constructed from unplasticised polyvinyl choloride (uPVC). Typically, the auger may pick up from 1 to 2 litres of compost and can handle small pieces of noncompostable materials such as plastic, stones and such like.

S' Several turns are typically needed to sufficiently fill the auger. Shaking or tapping the auger onto the side of a bucket or wheelbarrow releases the compost. In a preferred form, the auger follows the same principle as a post-hole digger. The compost can be incorporated into the soil as a useful fertilizer and soil conditioner.

In a typical installation, ventilation is effected by a 100 19 mm diameter 12 volt solar powered brushless DC motor driving a suitable fan. Preferably, the motor and fan are substantially silent, and may be assisted by a wind ventilator which is preferably adapted to prevent the entry ofi rain water and the like through the vent stack. When installed in a typical domestic situation such as a house, the height of the vent stack preferably exceeds the height of the roof ridgeline by approximately 500 mm. Using such an arrangement, fresh air may be drawn into the composting chamber through the chute or closed toilet seat which allows air to pass in leaving no odour trail for flies to follow.

The airflow aerates the compost in the chamber and V.te continues through the ventilator tube. Any excess moisture which has percolated onto the bottom of the chamber is evaporated off as air is drawn over it and out through the vent stack. In 0*000 special cases where a large amount of urine or water is added to the system, provision may be made to cicrulate water through the compost or to discharge an excess build up in a suitable manner by unsing a small automatically operated pump system.

20 Fine mesh flywire barriers are provided on both sides of oeoe° the fan and effectively exclude entry of any insects which may follow any odour trail from the expelled air. The wind operated ventilator is made with a stainless steel support shaft.

oo ~Replaceable ball bearings provide rotation of the wind operated ventilator on the vent stack. All other components are made from UPVC and provide a cheap long life ventilator.

Start-up of the system requires addition of an absorptive and biologically active compost, and compost producing organisms.

This may be achieved by the addition of fresh soil, leaf litter, tiger worms, earth worms and such like to the compost. The compost, when active, will contain a wide range of break down organisms and fungal grazers. At least a cubic metre of compost should be added to act as a moisture regulating buffer and habitat. This volume will fill the composting toilet to the minimum level required for start up.

Once the composting chamber has been primed with compost and soil organisms the toilet can be commissioned. Waste accumulates in a conical pile below the chute. This allows for an orderly and predictable sequence of microbial and micro-fauna and flora to become established and supported to complete each stage of break-down. It is believed that virulent pathogens and eoge 15 parasites are usually not competitive decomposers, and are eo0°° vulnerable to a complex array of microbial competitors, The competitive exclusion and predation brought about by a broad r spectrum of decomposers from bacteria and fungi, to multicellular crustaceans, mites, earthworms and such like encourages the elimination of dangerous organisms.

°Without relying on theroy or limiting the scope of this invention thereto, it is believed that an aerobic layer of decomposing waste most exposed to the ventilated area of the chamber is where the most active decomposition takes place. This is in essence modelled on the ecological population dynamics observed in a forest soil profile, where organisms decomposing the fresh litter are specifically adapted to the litter layer 21 conditions. The soil arthropods, insects and tiger worms introduced predominate in this layer and effect much of the mechanical break-down, and promote the rapid break down ip subsequent deeper profiles where micro organisms are the chief agents of decomposition. The final stages of decomposition appear to favour the activity of fungi which through the action of powerful enzymes break down the persistent organic residues such as lignins and remaining cellulose in the well ventilated deepest layers. Simulating the processes associated with the natural ecological sequence in forest soils, allows for stable population dynamics to prevail and appropriate equilibria to exist with respect to oxygen, water, temperature, carbon dioxide and nutrient gradients.

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The effective compost profile depth is believed to be dse.

gel• Ds 15 important as it relates to the requirement for a reasonably long o residence time for full decomposition to proceed and render the

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compost pathogen free. This system of break down does not rely on high temperatures being generated. A residence time of from three to five years may be considered typical. Shorter time spans may be possible for well managed compost input regimes where care is taken to provide sufficient absorptive high carbon e o inputs such as paper and cardboard in such a way as to avoid laminated compaction.

ouo• The height of the compost pile may be allowed to rie to just below the waste entry chute to have an effective volume of over two cubic metres. Some waste, once composted, will remain in place in the buffer zone. Excess moisture may be absorbed by 22 this area. If high temperatures or low oxygen levels prevail this area provides a refuge for organisms which can migrate through the compost such as earthworms, collembolla, mites, slaters and other vertebrate and invertebrate animals. If plants and/or mycota spread through the compost, then re-growth from and die-back to the buffer zone may occur with changing environmental conditions.

In order that this invention may be more readily understod and put into practical effect, reference will now be made to the use of a typical waste disposal apparatus. The problems encountered by compost toilet users may be avoided by careful adherence to sound day to day management practices. These include primarily the management of the nature and preparation of material added.

,ee 15 In addition to sewage, all organic kitchen scraps, domestic waste paper and cardboard may be added. About 1 to 2 kg per week of paper/cardboard/woodshavings/sawdust/crushed pine bark is needed for each person using the system to make good compost. It is desirable to crumple waste paper and mix it with kitchen 20 scraps in a lidded fly proof container they are generated.

Flies should be prevented from access to the scraps, as some fly larvae will survive and emerge through the chute if this hygiene is not adhered to. Tampons, sanitary pads, cotton wool and some non-synthetic clothes or rags may be safely converted into compost.

Unacceptable materials include metals, tin cans, plastic (particularly plastic bags), disposable nappies (unless the 23 plastic is removed), batteries, most chemicals, antibiotics, mineral oil, paints, strong biodegradable detergents and some textiles. Foam sponges may be disposed of if broken into small pieces.

Typically, the apparatus of this invention may be maintained by such measures as cleaning the seat chute periodically accordingly to personal hygiene preferences, extracting finished compost after a sufficient amount has accumulated, or sufficient time has passed, cleaning the fine mesh flywire barriers on both sides of the fan approximately every 3 months, maintaining or replacing the battery as required after several years.

It is important that the ventilation system should operate continuously. Power consumption in a preferred embodiment is 15 very small and may typically use between 20 and 50 kW-hr of power per year. If any odour is detectable at the chute a check may be made to see if the fan is operating.

It will of course be realised that while the above has been given by way of illustrative example of this invention, all such 20 and other modifications and variations thereto as would be o apparent to persons skilled in the art are deemed to fall within

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the broad scope and ambit of this invention as is claimed in the too* following claims.

Claims (13)

1. Organic waste treatment apparatus for treating organic waste continually introduced thereto and including:- a treatment chamber through which the organic waste material may pass in substantially plug flow; a compost outlet associated with the leading portion of the plug flow and through which treated material may be removed from said treatment chamber; an inlet through which organic waste material may be introduced into said treatment chamber to the trailing portion of the plug flow, and aeration means for aerating waste material resident in said treatment chamber and including an air permeable wall at 0*SO least partially supporting the leading part of said plug flow, *e 0

2. Organic waste treatment apparatus as claimed in claim 1, wherein said aeration means includes a vented air chamber in communication with said treatment chamber. *00040 Is..

3. Organic waste treatment apparatus as claimed in claim 2, wherein said air permeable wall includes a base wall portion which divides said air chamber from said treatment chamber. 0

4. Organic waste treatment apparatus as claimed in claim 3 wherein said base wall extends about the upper portion of a lower extension of said treatment chamber.

Organic waste treatment apparatus as claimed in claim 4, the lower extension of said treatment chamber extends downwardly to the lowest part of said air chamber.

6. Organic waste treatment apparatus as claimed in any one of the preceding claims, wherein said compost outlet includes extraction means for extracting treated waste from said treatment chamber.

7. Organic waste treatment apparatus as claimed in claim 6 when appended to claims 4 or 5, wherein said extraction means includes an extraction tube which terminates adjacent said lower extension. 0 *00

8. Organic waste treatment apparatus as claimed in claims 7, wherein said extraction means includes an extraction tube which penetrates the waste material and is adapted to admit an auger.

9. Organic waste treatment apparatus as claimed in any one of the preceding claims wherein said treatment chamber and said outlet are so formed that at least some waste material is retained therein in a substantially biologically inactive manner and the remainder of the waste material flows to said outlet.

Organic waste treatment apparatus as claimed in any one of the preceding claims, wherein said treatment chamber includes a 26 base wall, a side wall extending upwardly therefrom and a top closure wall and wherein said inlet and said aeration means are located in or pass through said top closure wall.

11. Organic waste treatment apparatus as claimed in any one of the preceding claims, wherein said waste treatment apparatus is in the form of a composting toilet and said inlet is in the form of a toilet pedestal.

12. Organic waste treatment apparatus as claimed in any one of the preceding claims, including conduit means through which air may be drawn from said inlet to said air chamber.

13. Organic waste treatment apparatus substantially as hereinbefore described with reference to the accompanying drawings. DATED THIS Fourth DAY OF January, 1993. DEAN OSMAN CAMERON BY BY PIZZEY COMPANY Vcoo 27 ABSTRACT Organic waste treatment apparatus (10) for treating organic waste continually introduced thereto includes a treatment chamber (11) through which the organic waste material may pass in substantially plug flow, a compost outlet (30) associated with the leading portion of the plug flow and through which treated material may be removed from the treatment chamber an inlet through which organic waste material may be introduced into the treatment chamber (11) to the trailing portion of the plug flow and aeration means (40, 41, 42) for aerating waste material resident in the treatment chamber (11) and including an air permeable wall (14) at least partially supporting the leading 1 part of the plug flow. Preferably at least some of the treated waste remains in the treatment chamber indefinitely as inactive oat* "Set treated waste (56) which provides a buffer zone where mobile U organisms may be able to take refuge should the environmental conditions in the remainder of the waste material in the holding tank (11) become unfavourable and/or the buffer zone may provide an inoculum means for the remainder of the waste material in the holding tank whereby microorganisms may be introduced into the remainder of the waste material under a range of operating conditions.