GB2304127A - Waste system for toilets - Google Patents

Abstract

A process and apparatus for the disposal of toilet waste separating the liquid portion from the solid portion of the toilet waste, disposing of the liquid portion of the waste by drainage, forming a mixture by combining the solid portion of the waste with a quantity of flammable material having structural properties that retain air passages within the mixture, storing the mixture in a chamber, and burning the mixture within the chamber.

Description

Waste System for Toilets Technical Field This invention relates to an improved method of waste disposal to be used with toilets that cannot be connected to sewer drains and particularly to be used with dry toilets with disposable bowl lining material.

Background Worldwide water shortages and the expense of cleaning up polluted water has resulted in an increasing need to dispose of toilet waste without the use of water or centralised sewage processing.

Toilets which do not use water and which do not depend on central sewage processing fall into four types - incinerating toilets, sterilizing toilets, composting toilets and lined toilets.

Incinerating toilets use an external source of energy to heat the waste, evaporate all the liquid waste and burn the remaining solid waste. Disadvantages are the high initial cost, the high operating cost and the use restriction imposed by the incinerating cycles. Similarly, sterilizing toilets use external energy to evaporate urine and heat the faeces to kill the bacteria but require the inconvenience of frequent manual clean out for disposal elsewhere. Composting toilets store the waste in an aerated chamber and use aerobic bacteria to digest or oxidise the waste over a long time period. Composting toilets are bulky and relatively expensive installations which need frequent manual attention. Lined toilets surround the waste in plastic and transport it to a storage container for eventual manual removal and separate disposal elsewhere.

None of the foregoing waterless toilets perform their function as conveniently and with as little user attention as a conventional water flushing toilet. However, the water flushing toilet does not have to actually dispose of the waste. It uses clean water to move the waste to a remote location where more expensive disposal processes are undertaken. In many parts of the world this is no longer an economically viable procedure.

Most toilets which combine solid and liquid waste together cannot take advantage of the fact that liquid toilet waste containing urine and any flushing water is much easier to dispose of than solid toilet waste containing faeces, paper, diapers, fibrous sanitary items and potentially harmful pathogens. Urine which is normally sterile and constitutes the bulk of human waste is readily absorbed into soil or dispersed in waterways without environmental harm whereas solid toilet waste requires special treatment before it can be released into the environment.

To eliminate a health hazard it would be better to incinerate the solid toilet waste but the high water content and the low heating value of the waste makes this expensive and complicated.

Disclosure of Invention The cost and inconvenience of disposing of toilet waste at the toilet site can be greatly improved by the present invention which is particularly applicable to lined toilets and which provides means by which all the solid toilet waste can be incinerated economically without the use of external energy.

The present invention is a process which includes the following steps: 1) Separating liquid toilet waste from solid toilet waste, 2) Adding to the solid waste a small quantity of combustible material of relatively higher heat value having structural properties which will assist the process of drying by increasing the aerated surface of the solid waste and prevent the compaction of accumulated waste deposits, 3) Drying the solid waste mixture in a container to a low moisture content that will in combination with added heat value allow self sustained combustion and 4) Igniting and burning of the dried waste in situ.

This process can be accomplished by apparatus of relatively small proportions which would be suitable for installation in residential premises. The process can also be applied to portable toilets but the absence of chimney vents would require that the incineration be done elsewhere.

By way of example, this waste disposal process can be described more in detail by reference to a lined toilet such as described in UK patent application GB 9405323.8. This type of toilet has a bowl lined with thin sheet material which is renewed each time the toilet is used.

The sheet material could be polythene which burns easily and has a heat value of 46,500 kilojoules per kilogram. This value is greater than coal or fuel oil and is three times higher than dry faeces or paper.

The process of 'flushing' this toilet causes retention of the solid waste within the liner material and allows most of the liquid waste to drain away and be collected separately. The present invention provides for a pump which receives the soiled liner sheet containing the solid waste. This pump forces the waste material into the bottom of a solid waste container and when doing so cuts and crumples the plastic film so that the resulting wad of plastic sheet and waste contains air spaces and air passages.

At the bottom of the solid waste container the crumpled plastic continues to drain any free liquid into a receptor located beneath the solid waste container. The solid waste container is separated from the liquid receptor by a particle filter which allows only the essentially liquid material to pass through. Subsequent 'flushing' cycles force the previously drained waste material higher up into the container where in a fixed toilet installation (as opposed to portable toilets) provision can be made for the container walls to be perforated and to be surrounded by a duct through which drying air can flow and be vented through a chimney to the outside atmosphere.

As the waste material rises in the container it gets progressively drier. By the time it reaches the top after a month or more it is sufficiently dry so that it will sustain combustion when ignited. At that time the dry upper waste material could be removed and burned elsewhere or it could be burned within the container using the air duct and the chimney to remove the combustion gases. The toilet can be used without interruption even during incineration intervals.

The polythene liner provides the higher heat value to sustain the process in the presence of moist waste. Polythene by itself burns cleanly without residue or noxious gases. Once ignited the burning will proceed down the waste container to a level where air has been excluded or where the moisture content is too great. Any lumps of moist material not consumed would be left on the top of the remaining waste where the optimum drying conditions would ensure complete combustion at the next firing cycle.

It is recognised that this process does not necessarily require the use of polythene liner sheet or a lined toilet. Any inexpensive, high heat value material with aerating properties could be added to the toilet waste to assist drying and to aid sustained combustion. Also, it is recognised that the dimensions of the solid waste container influence the drying time as well as the intensity and rate of burning.

The solid waste container could preferably be tall and relatively narrow in section to maximise the surface area exposed to the drying air. A container 0.15 metre in diameter and 2.0 metre high would have enough volume to contain the solid toilet waste output of a family of three for three months before removal or burning was require It is normal for moist toilet waste to biologically decompose. In the absence of air anaerobic bacteria would release unpleasantly smelling gases that would be undesirable even if vented to the outside atmosphere. However, the air passages created by the crumpled liner material or any other aerating additive would encourage digestion by aerobic bacteria the products of which are not objectionable. As drying decreases the moisture content, the biological activity will also decrease.

The liquid waste that drains into the lower receptacle is mostly urine which is normally a sterile liquid containing harmless compounds and salts but it could be contaminated by bacteria from the faeces. Urine would normally be discharged without treatment into a sewer drain or dry well but if the circumstances require it could be sterilized by chemicals or by ultra violet radiation before discharge.

Without a connection to an outside vent or a liquid drain it is not practical for portable toilets to dispose of the waste in situ. Nevertheless, the essential processes of this invention i.e. separation of liquid and solid waste, adding aerating material, draining and drying can be accomplished but only over a shorter period due to limited storage space. The resulting waste would have a relatively higher moisture content but would with the added heat value still incinerate well in the presence of other combustibles. Furthermore, the waste containers could be made of polythene which would be disposed of or burned along with the contained solid waste thus minimising unpleasant handling. The liquid would be drained from its portion of the disposable container before incineration.

According to a preferred aspect of the present invention there is provided a waste system for toilets comprising, a lower container adapted to receive liquid waste, the lower container having means for draining the liquid waste, an upper container adapted to receive solid waste, the upper container having means for the passage of air through the container, a toilet drain pipe connected to the upper container, the upper container being mostly above the level of the toilet drain pipe connection and the lower container being mostly below the level of the toilet drain pipe connection, a particle filter interposed between the internal volume of the upper container and the internal volume of the lower container, the filter being dimensioned to allow the passage of the liquid waste into the lower container and to contain the solid waste in the upper container, a pump within the toilet drain pipe to force the solid waste into the lowermost portion of the upper container where it can drain without wetting previously drained material, means for adding to the waste a sheet material of relatively high fuel value which when crumpled or serrated by the pumping action increases the aerated surface of the solid waste within the upper container and a means to incinerate the solid waste within the upper container.

Further, according to a preferred aspect of the present invention the container, the particle filter and the connection to the toilet drain pipe can be fabricated from thin combustible materials and which when manufactured lies flat but when in use expands to contain the incoming toilet waste. This disposable container can also be provided with a lowermost spout with an openable seal to assist the removal of the liquid waste, an upper vent with an integral chemical filter to prevent the escape of odorous chemicals while allowing the ingress of air and a soluble chemical biocide packaged into the lower liquid portion to maintain sterile conditions.

Brief Description of Drawings This invention will be further described by way of example only, by reference to the accompanying and purely diagrammatic drawings, in which: Figure 1 is a side view of a lined, dry toilet exposing a section through the waste pump with the piston in the closed position:: Figure 2 is as figure 1 but with the piston partly retracted; Figure 3 is as figure 1 but with the piston fully retracted; Figure 4 is section view of the side of the waste holding incinerator container; Figure 5 is a side view of a lined, dry toilet exposing a section through the waste pump and an attached disposable waste container; Figure 6 is as figure 5 but showing a method of removing the disposable waste container; Figure 7 is an end section view of the disposable waste container, and Figure 8 is an end section view showing a disposable waste container of an alternative type of construction.

Best Mode for Carrying Out invention A lined toilet shown in Figure 1 has a bowl 15 which is lined with plastic sheet 16 which is shown emerging from the bowl's exit aperture 17 and entering into a pump housing 18 where the end of the plastic sheet 16 is pinched closed by the pressure of a piston 19 against an opposing surface on the pump housing 1 18. When the toilet is used a slope at the bottom of the bowl 15 and a slope at bottom of the exit aperture 17 cause liquid waste to drain down and accumulate in the plastic sheet 16 near the piston 19 whereas solid waste which does not flow readily is retained in another part of the plastic sheet 16 in the centre of the bowl 15.In Figure 2 the flushing cycle has started and the piston 19 has partly retracted thus releasing the pinched end of the plastic sheet 16 and allowing the liquid waste to drain into the bottom of the pump housing 18 where the it can flow along the bottom of a drain pipe 20. Figure 3 shows the piston 19 fully retracted thus leaving the pump housing 18 open to receive the soiled plastic sheet 16 containing any solid toilet waste without the liquid waste which has already drained from within the plastic sheet 16. To complete the flushing cycle the piston 19 is advanced to close the open pump housing 18 and force the soiled plastic sheet 16 containing the solid waste into the drain pipe 20 and simultaneously forcing the waste from previous flushing cycles further along the drain pipe 20.As the piston 19 reaches the end of its advance a clean portion of the plastic sheet 16 is again pinched closed and simultaneously a cutter 21 at the end of the piston severs the soiled portion of the plastic sheet 16 from the clean portion.

Now referring to Figure 4 the drainpipe 20 extends from the end of the pump housing 18 over a particle filter 22 through which the liquid waste drains into a lower container 23 and from there through an optional sterilizing device 24 before entering the discharge pipe 25. The plastic sheet 16 containing the solid waste is progressively pushed along the drain pipe 20 which bends upward into a solid waste container 26. The upper portion of the container walls 27 are made of metal mesh which exposes the waste sheet material 16 to the air within a duct 28 which surrounds the solid waste container 26. Air enters the duct 28 through lower ports 29 and passes out the top through a chimney 30 to the outside atmosphere. The waste material within the container 26 gets progressively drier as it is pushed upwards toward the top. When dry enough to support combustion the waste sheet material 16 can be ignited manually through a port 31 in the duct or it could be ignited automatically by an ignition device 32 triggered by a sensor. The waste sheet material 16 together with the solid waste burns progressively downward from the top of the container 26 until extinguished by excessive moisture content or until air is excluded by the air tight walls 33 on the lower portion of the container 26.

Combustion gases pass up through the chimney 30 and any residual ash which falls out through the container walls 27 can collect on the bottom of the duct 28 and be removed through a clean out door 34.

A lined toilet intended for portable use is shown in Figures 5 & 6 where the pump housing 18 is connected directly to a disposable waste container 35 which is divided into an upper compartment 36 to contain the soiled sheet material 16 together with the solid waste and a lower compartment 37 to contain the liquid waste. The upper compartment 36 is separated from the lower compartment 37 by a particle filter 38 which allows only the essentially liquid waste to pass into the lower compartment 37. The disposable waste container 35 is connected to the pump housing 18 by means of an extendable sleeve 39 which is clamped around the outside of the pump housing 18.The weight of the container 35 with its contents is supported on bracket 43 which could extend as shown in Figure 6 to facilitate removal of the extendable sleeve 39 from the pump housing 18 by providing room to apply a tie 44 to the sleeve 39 thus sealing the container 35 before disconnecting from the pump housing 18.

The handle 45 facilitates the manual lifting of the container 35 for disposal elsewhere.

Before disposal by incineration the liquid waste can be drained from the lower compartment 37 by opening a sealed spout 46. The lower compartment 37 can also contain a biocide chemical which will keep the accumulated liquid waste 48 sterile. The upper compartment 36 may be provided with an air vent 47 into which is sealed a filter to prevent the escape of smells or contaminated particles. The air vent 47 could assist the disposal of the container 35 by allowing its volume to be reduce by squeezing and would also discourage odour producing anaerobic bacteria.

The disposable container 35 can be manufactured from flat thermoplastic sheets the seams of which are heat sealed together to form the compartments 36 and 37 and the sleeve 39 as well as the small passages that form particle filter 38. The flat plastic container will expand in use to contain the waste as shown in cross section in Figure 7. Alternatively, as shown in Figure 8, the particle filter 38 could be provided in the form of a textile sheet 49 also heat sealed into the disposable container 35. The textile sheet particle filter 49 has more surface area than the thermoformed particle filter 38 and would be less likely to become clogged.

Claims (7)

1. A process for disposal of toilet waste having a liquid portion and a solid portion, the process to include the following operations: separating the liquid portion from the solid portion of the waste by gravity flow or by filtering or by both, disposing of the liquid portion of the waste by drainage, forming a mixture by combining the solid portion with a quantity of flammable mateial with structural properties that retain air passages within the mixture, storing the mixture in a chamber, and burning the mixture within the chamber.

2. A process for disposal of toilet waste having a liquid portion and a solid portion contained within a wrapper formed with combustible material, the process to include a sequence of operations as follows: After each toilet use, separating the liquid portion from the solid portion by draining away the liquid portion through openings in the wrapper, transporting the wrapper with the solid portion into a chamber and, after a number of toilet uses, burning the wrapper and the solid portion within the chamber.

3. A toilet waste system for disposal of liquid waste and solid waste comprising; combustible sheet material capable of being formed into a container for holding toilet waste, apparatus to transport the sheet material containing the toilet waste into a sump having a bottom wall, a drain hole in the bottom wall through which the liquid waste can drain out of the sump, a particle filter across the drain hole to retain the solid waste within the sump and further apparatus to transport the solid waste and the sheet material from the sump into a storage chamber.

4. A toilet waste system for disposal of liquid and solid waste according to claim 3 wherein the storage chamber is adapted by means of vents for the combustion of the solid waste within the storage chamber.

5. A toilet waste system for disposal of liquid waste and solid waste comprising; combustible sheet material capable of being formed into a container for holding toilet waste, a storage receptacle having an upper chamber and a lower chamber divided by a wall, the wall having perforations through which the liquid waste can drain into the lower chamber while the solid waste is retained in the upper chamber, an opening in the upper chamber adapted to receive the toilet waste, transporting apparatus to move the sheet material containing toilet waste through the opening into the upper chamber and means for draining the liquid waste out of the lower chamber.

6. A toilet waste system for disposal of liquid and solid waste according to claim 5 wherein the storage receptacle is formed from combustible material and has means for detaching from the transporting apparatus for disposal by burning.

7. A toilet waste system for disposal of liquid and solid waste according to claim 3 or 5 wherein there is provided a cutter to slit the sheet material to assist the liquid waste to drain out of the the container formed by the sheet material.