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Title:
COMPOSTABLE TOILET
Document Type and Number:
WIPO Patent Application WO/2010/142940
Kind Code:
A1
Abstract:
The toilet comprises a container T formed of biodegradable material, incorporating a bowl (1) for receiving human faeces and urine, and a close- fitting lid (2). The surfaces of the bowl and lid are shaped such that when a number of filled containers are stacked one upon another air cavities are enclosed within the stack. The air pockets enhance the composting process so that composting of the toilets results in a fertilising compost in which nutrients are captured for plant use and pathogens have been destroyed. The container is formed from a fibrous carbon-based material to improve the carbon balance of the composted material. The bowl is waterproofed by incorporating a biodegradable moisture resistant material such as clay, pva or lactic acid polymers. The compostable toilet preferably includes soak sheets formed of a biodegradable moisture- absorbent material. The soak sheets may incorporate agents which are beneficial to the composting process, which may comprise live biological material such as bacteria, yeasts and fungi.

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Inventors:
BATSTONE CHRISTOPHER (GB)
BATSTONE SUSANNAH (GB)
Application Number:
PCT/GB2010/001105
Publication Date:
December 16, 2010
Filing Date:
June 07, 2010
Export Citation:
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Assignee:
BATSTONE CHRISTOPHER (GB)
BATSTONE SUSANNAH (GB)
International Classes:
A47K11/02
Foreign References:
DE4019771A11992-01-09
US20090038066A12009-02-12
DE102005061233A12007-06-21
DE4416082A11995-11-09
DE9209074U11992-09-17
DE29607144U11996-08-14
GB2337059A1999-11-10
GB2369552A2002-06-05
GB2448945A2008-11-05
US5524301A1996-06-11
US5524301A1996-06-11
GB2448945A2008-11-05
US6047414A2000-04-11
US20060117475A12006-06-08
US20090038066A12009-02-12
US20090105675A12009-04-23
US20040098794A12004-05-27
US4980023A1990-12-25
Attorney, Agent or Firm:
CRASKE, Stephen (Patent Law Chambers15 Queens Terrace, Exeter EX4 4HR, GB)
Download PDF:
Claims:
CLAIMS

1. A compostable receptacle which comprises a container. (T) formed of biodegradable material, the container incorporating:

- a waterproof bowl (1) for receiving biological waste material, the bowl incorporating a moisture resistant material and comprising a base (10) surrounded by an upstanding side wall (11); and

- a close-fitting lid (2) which covers the bowl and encloses its contents when not in use; the bowl and the lid each being moulded in a single piece without joins or creases and being configured such that, when a number of filled containers are stacked one upon another, an enclosed air space is formed between the lid of one container and the base of another container to enhance the composting process.

2. A compostable receptacle according to Claim 1 in which the container is formed from a carbon-based material containing plant fibres, said material being present in a quantity which is sufficient to achieve effective composting.

3. A compostable receptacle according to Claim 2 in which the carbon-based material includes one or more of cellulose, lignin, starches and hemicellulose.

4. A compostable receptacle according to Claim 1 in which the moisture resistant material includes one or more of clay, pva and lactic acid polymers.

5. A compostable receptacle according to Claim 1 which incorporates one or more agents which are beneficial to the composting process.

6. A compostable receptacle according to Claim 5 in which the beneficial agent comprises live biological material which controls the breakdown of the container and its contents.

7. A compostable receptacle according to Claim 6 in which the live biological material includes one or more of bacteria, yeasts and fungi.

8. A compostable receptacle according to Claim 5 in which the beneficial agent includes an enzyme which promotes breakdown of the container structure.

9. A compostable receptacle according to Claim 5 in which the beneficial agent includes minerals necessary for biological activity.

10. A compostable receptacle according to Claim 1 in which the side wall (11) is outwardly divergent away from the base (10).

11. A compostable receptacle according to Claim 1 in which the base of the bowl includes a central region formed as a raised platform (12) surrounded by a continuous peripheral channel (13).

12. A compostable receptacle according Claim 1 in which at least one of the opposing surfaces (12, 20) bounding the said air space comprises an array of depressions (21).

13. A compostable receptacle according to Claim 12 in which the lid includes a planar central region (20) formed with an array of discrete depressions (21).

14. A compostable receptacle according to Claim 1 which includes a supply of soak sheets (30) formed of a biodegradable moisture- absorbent material.

15. A compostable receptacle according to Claim 14 in which the soak sheets (30) are formed of fibrous carbon-based materials.

16. A compostable receptacle according to Claim 14 in which the soak sheets incorporate one or more agents which are beneficial to the composting process.

17. A compostable receptacle according to Claim 16 in which each soak sheet comprises top and bottom layers joined around their periphery to enclose the beneficial agent.

18. A compostable receptacle according to Claim 17 in which the beneficial agent is present in layers alternating with separator sheets (36, 37) of biodegradable moisture-absorbent material.

Description:
COMPOSTABLE TOILET

TECHNICAL FIELD OF THE INVENTION

This invention relates to a compostable toilet which is primarily intended for collecting human faeces and urine, although the collection of other organic matter is not precluded, such as animal faeces, food scraps, cooking fire ash or charcoal.

BACKGROUND

2.6 billion people on our planet do not have access to a toilet, and "flying toilets" are common in slum areas. When faced with no other facilities faeces is tied in plastic bags which are simply discarded. Faeces and urine left on the ground pollutes water courses, is spread by human feet, insects, animals and by the wind, and contributes to the proliferation of infections. Around 5,000 children die each day from water borne diseases and many more are weakened by infections and, as a result, suffer further health problems. Malnourished people are more likely to succumb to diseases caused by poor sanitation, and lack of sanitation leads to degrading living conditions both in rural and urban communities.

Flushing away human excrement pollutes rivers, lakes and coastlines, and there is ever increasing pressure on global supplies of fresh clean water. Using water to transport human excrement, to which chemical and industrial wastes are often added, results in a wet, smelly and toxic product that needs extensive treatment before it can be disposed of. Such waste materials are often banned from use on agricultural land due to contaminants. Water systems are also expensive to construct.

Fertile land area is inadequate to meet human food requirements leading to global food insecurity. Impoverished, infertile, and exhausted soils lack humus and cannot hold moisture, leading to desertification and crop failures. Artificial and mineral based fertilisers are running out. Potash reserves will only last 30 years, and nitrogenous fertilisers are made from natural gas which is a fossil fuel. 7 tons of gas are required to make 1 ton of ammonium nitrate.

Composting is the biological decomposition and stabilization of organic substrates, under conditions that allow development of thermophylic temperatures as a result of biologically produced heat, to produce a final product that is stable, free of pathogens and plant seeds, and can be beneficially applied to land. Composting latrines are sometimes seen as a partial solution to the disposal of human waste. However, these need building, cleaning and emptying, requiring a large initial capital investment and ongoing running costs. Human excreta should not be used to grow food crops without treatment to kill pathogens and parasites. Furthermore, these latrines do not conserve all the plant nutrients. Leaching of liquids can contaminate water courses, and deep pits sometimes collapse. Flies and smells are always a problem. Conventional or composting latrines are not easy for all ages to use; Small children can fall in to the pit, and old or disabled people struggle with steps. US 5 524301 A discloses a lightweight, portable toilet which is disposable after use. The toilet is formed of biodegradable corrugated paper board which is capable of being incinerated or buried in the earth. The disposable toilet includes a seat member containing a rounded rectangular opening which is placed on a substantially rectangular base which is open at the bottom to allow human waste excretions to fall into a pre-excavated hole in the earth's surface. After use, the toilet can be moved to a new location or disposed of and the hole covered with soil. Similar disposable toilets formed of paper board with creased and jointed panels are disclosed in GB 2 448 945 A, US 6 047 414, US 2006/0117475 A1 and US 2009/0038066 A1.

US 2009/0105675 A1 discloses a portable biodegradable urine collection tube which comprises a base and lid formed of cylinders closed by cardboard discs.

US 2004/0098794 A1 discloses a disposable urine collection device which comprises a glove attached to an absorbent pad. The pad is composed of a waterproof plastic housing containing various absorbent layers.

US 4 980 023 A discloses a method of manufacturing a paper or cardboard product incorporating a cellulase enzyme which accelerates decomposition of the product when exposed to moisture. The product can be provided with a waterproof plastic coating without risk of destroying the enzyme.

The present invention seeks to provide a new and inventive form of toilet which is low cost, easily transportable, useable anywhere, hygienic, and is capable of providing a useful well balanced source of nutrients for agricultural use in a configuration which promotes and enhances the composting process.

SUMMARY OF THE INVENTION

The present invention proposes a compostable receptacle which comprises a container formed of biodegradable material, the container incorporating:

- a waterproof bowl for receiving biological waste material, the bowl incorporating a moisture resistant material and comprising a base surrounded by an upstanding side wall; and

- a close-fitting lid which covers the bowl and encloses its contents when not in use; the bowl and the lid each being moulded in a single piece without joins or creases and being configured such that, when a number of filled containers are stacked one upon another, an enclosed air space is formed between the lid of one container and the base of another container to enhance the composting process.

The deliberate incorporation of air pockets when the containers are stacked significantly enhances the composting process so that composting of the receptacles results in a fertilising compost in which nutrients are captured for plant use and pathogens have been destroyed.

The container is preferably formed from a carbon-based material containing plant fibres, including, but not limited to, cellulose, lignin, starches and hemicellulose, said material being present in a quantity which is sufficient to achieve effective composting. Such materials significantly enhance the composting process by improving the carbon balance of the composted material.

The bowl is of a waterproof nature so that liquids are retained and breakdown does not commence immediately. Waterproofing may be achieved by means of a biodegradable moisture resistant material such as clay, pva or lactic acid polymers.

The receptacle preferably incorporates one or more agents which are beneficial to the composting process. The beneficial agent may, for example, comprise live biological material which accelerates breakdown of the container and its contents, such as bacteria, yeasts and fungi in various combinations. Another example of a beneficial agent is any enzyme which promotes breakdown of the bowl structure. Minerals necessary for biological activity may also be included.

In order to maximise the chance of maintaining air cavities when the units start to decompose at least one of the opposing surfaces bounding the said air space preferably comprises an array of surface depressions.

The compostable receptacle preferably includes soak sheets formed of a biodegradable moisture-absorbent material to prevent spillage or leakage of fluids. The soak sheets absorb liquids and makes it less unpleasant when the lid is removed to use the receptacle again. When such soak sheets are provided the beneficial agent is preferably incorporated in the soak sheets.

BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a general view of a compostable toilet in accordance with the invention, showing a lid and two bowls;

Figure 2 is a top view of one of the bowls;

Figure 3 is a vertical section through the bowl on plane A-A of Fig. 2, showing two bowls and a lid stacked as in Fig. 1 ;

Figure 4 is a general view of a soak sheet for use in the compostable toilet;

Figure 5 is an exploded view of the soak sheet;

Figure 6 shows the compostable toilets being buried in the ground after use;

Figure 7 shows the toilets undergoing decomposition; and

Figure 8 shows how the composted material may be directly used in agriculture.

DETAILED DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a compostable squatting toilet which is specifically designed for use in a squatting position to collect human faeces and urine, although the shape and configuration of the toilet can be adapted to make it suitable for seated use. Each toilet comprises a container T which includes a single bowl 1 with a close-fitting lid 2. In the drawing two bowls are shown for reasons which will become apparent. Fibrous organic waste materials are particularly preferred, forming a valuable source of carbon to compliment the nitrogenous waste materials during decomposition. There is currently a surplus of around 4.6 millions tons a year of recycled paper and card in the UK, and local authorities are having to incinerate it or dispose of it to landfill. Post-consumer recycled paper or cardboard is therefore a good choice, along with crop residues (straw, rice hulls), miscanthus grass, bamboo, sawmill by-products, recycled wood etc. A complete squatting toilet would utilise close to 1kg of paper, cardboard or timber waste, but other versions could use more.

The bowl and lid 1 , 2 are each moulded in a single piece without joins or creases. Any suitable method of moulding the specified materials into solid hollow shapes can be used. For example, the fibrous material could be mixed with water to form a fibrous pulp which is sprayed into a mould and dried or pumped into a mould and the liquid component drawn off by application of negative pressure.

The bowl 1 and preferably also the lid 2 are treated to make them substantially waterproof (non-absorbent) by incorporation of a suitable additive or application of a biodegradable moisture resistant coating. Suitable biodegradable waterproofing agents include clays, pva and lactic acid polymers.

Referring to Fig.s 2 and 3, the form of bowl 1 which is shown in the drawing has a generally trapezoidal base 10 with rounded corners, surrounded by an upstanding side wall 11 which diverge slightly in an upward direction. A central region of the base is formed as a flat raised platform 12, surrounded by a continuous peripheral channel 13. The top margin of the side wall 11 is curved outwards to form an outwardly- extending flange 14 of curved cross-section with a concave underside. The lid 2 is of similar trapezoidal profile to the base 1 and includes a planar central region 20 formed with an array of wells 21 formed by discrete depressions in the region 20. The outer periphery of the central region is surrounded by a shallow upward ramp 22 which leads into an outwardly-extending flange 23 of curved cross-section with a concave underside. When the lid 2 is placed on the bowl 1 the flange 23 fits tightly over the flange 14 to hold the lid in place and seal the contents against leakage.

After each use the waste material deposited in the bowl 1 is preferably covered with a soak sheet 30, one of which is shown in Fig.s 4 and 5. The soak sheet absorbs liquids and makes it less unpleasant when the lid is removed to use the toilet again. Again, the soak sheet may be formed of fibrous carbon-based materials such as recycled paper or card etc.

The compostable toilet of the present invention incorporates an beneficial agent containing live biological material, which is preferably incorporated into the soak sheet. The use of suitable biological activators within the absorbent soak sheets enable safe treatment of the human waste ensuring that pathogens and parasites will be destroyed by a combination of time and temperature. A specially blended activator can be incorporated into the soak sheets for a particular geographical region to provide populations with the correct balance of micro-organisms to achieve safe and thorough decomposition and treat the particular biological hazards which are predominant in that region. A typical biological activator may comprise a blend of bacteria, yeasts and fungi with some minerals. Thus, in a typical soak sheet as shown in Fig. 5 the soak sheet may comprise top and bottom layers 31 and 32 which are joined around their periphery, e.g. by means of a suitable adhesive. The biological activator may be added in layers 33, 34 and 35 alternating with separator sheets 36 and 37 of the same absorbent material. On decomposition of the toilet the presence of the carbon-rich organic materials in the container and soak sheets together with the biological activator results in a fertilising compost in which nutrients are captured for plant use and pathogens have been destroyed.

The compostable toilet functions as a low cost, private and convenient water-less squat pan which is intended to be used when required until full. Urine collection is necessary to facilitate decomposition. One toilet may hold between 5 and 10 litres of human output (liquid and solid) and may thus contain up to a weeks output for an average person, or one day for a family. Users add an activator sheet after each solid deposit. This is not so important after the addition of urine only, although the sheets will reduce splashing which may be a concern for female users. Toilet paper, leaves or local equivalent can also be incorporated, if used. If anal cleansing with a small amount of water is customary, the toilet may fill more quickly. The unit may be kept lidded to avoid smells or access to flies. Food waste could be added to units, if desired.

Hand cleaning facilities should be made available to reduce spread of infection. Biodegradable wipes could be used and added to the contents of the toilet if an environmentally safe sanitizer such as PAA (peracetic acid) is used.

The toilet hygienically contains waste for up to 28 days allowing ample time for storage or transport before composting. Sealed units can be placed in a nearby composting trench or transported to a local composting site. The units can be stacked up to three high when filled. As shown in Fig. 3, the base of one unit fits snugly into the lid of another unit, seated firmly on the central region 20. It will also be noted that a substantial enclosed air pocket is formed between the raised base platform 12 and the central region 20, which is further enhanced by the individual wells 21. The air is important to enable aerobic organisms to work, which raise the temperature to kill pathogens. The separate wells 21 ensure that pockets of air are likely to remain even when the stack starts to collapse during decomposition.

Fig. 6 shows the filled containers T stacked in a trench ready for burial. The containers are normally stacked in alignment, but some of the containers may also be placed at 90° to the stack, as shown. Wooden poles P may be inserted into the trench, as shown. When filled, the trench is back-filled to cover the compostable toilets, possibly with material from the next trench, taking care to avoid compaction, so that the decomposition process can begin, as shown in Fig. 7. After back-filling, the poles are removed to provide air channels C to the surface. The absorbent structure of the soak sheets, retains the moisture while composting and prevents leaching of liquids. When the composting is complete plants can be grown directly in the composted material, as in Fig. 8. Cropping can generally commence after 12 months. The soil will be enriched and moisture retention will be improved. Shelter belts, or trees for fuel, will thrive if the land is not needed for food crops.

This composting system stops insects from breeding, eliminates pollution from leaching and prevents loss of plant nutrients. The recycled paper and card waste acts as a valuable carbon source to ensure a good balance in the composted mix, while urine contains the main proportion of nitrogen which is important for plant growth. Raw human waste will compost safely and efficiently if the carbon:nitrogen ratio is corrected, and adequate air and moisture are available. The compostable units aim to provide an ideal carbon:nitrogen ratio of 30:1 for thermophilic decomposition, and then breaks down with the contents to provide balanced nutrients in situ ready for planting. The biological additives may ensure that the composting mix heats to above 5O 0 C so that virtually all pathogens and parasites are killed.

The compostable toilet can be used in wide range of climates and soil types and allows the plant nutrients to be directly recycled to crops in rural areas, without secondary handling. Different versions can be produced to suit different cultures and situations, for example a larger weight bearing version where seated excretion is generally practised.

The units can be used safely by all ages and by disabled people. They give privacy, hygiene and convenience, are lightweight and inexpensive to manufacture and transport, using widely available technology and a variety of substrates.

The compostable toilet system can be deployed right at the outset of displaced populations, or introduced to more established communities alongside current practices. Use of the system has benefits by providing an immediate reduction of new contamination of surroundings, and removal of breeding areas for flies and mosquitoes around latrines. Infectious individuals can be isolated to prevent contamination of communal latrines. Drinking water will be safer, with less need for chemical treatment, and challenge from pathogens and parasites will reduce over time as levels in the environment decline. The system is safe and private to use, enabling women to not have to wait until dark, or risk attack from humans or animals while in the bushes. People in rural areas will have better nutrition as the soil structure improves, enabling them to resist disease and parasites. Any surplus food could generate income for education or medicines.

Although 100% control of human parasites, particularly ascaris, is difficult to achieve the composting toilet can incorporate agents which help to control known parasites. The introduction of the composting system can also be combined with worming regimes.

When used in rural areas where land is available, filled units should be placed in shallow trenches, covered with topsoil, holes for air ingress incorporated and then allowed to compost for twelve months. Moisture levels should be monitored as this will have the biggest impact on adequate levels of microbial activity. The area can then be planted with crops or amenity trees. No secondary handling of the waste is needed.

When deployed in built up areas, full units would need to be taken to composting sites where rapid and hot composting can be achieved. Full breakdown should occur in about eight weeks. Climatic conditions will affect composting management. The finished product resembles loamy earth and is not offensive. For sale and longer distance transport, drying will be needed. Vermicomposting (with earthworms) could result in harvest of high protein animal feed, suitable for pigs, chickens, ducks or fish. The end fertiliser is able to increase soil moisture holding capacity, biological activity and a promote a better crumb structure.

Off site composting in hot climates will result in a natural, soil conditioning fertiliser which can be dried, pelleted and distributed. The pelleting process generates heat so will be an extra safeguard of pathogen destruction.

Bio-gas production using the compostable toilets will still leave residues which are suitable for application to crops. One litre of human faeces can yield 50 litres of biogas, which can replace firewood for cooking, reducing deforestation and saving collection time each day, reducing smoke pollution within the dwellings and provide lighting which improves safety and allows continued education

Unlike composting latrines, no cleaning, building or maintenance is required. No sanitizer chemicals are required, and less chlorine is needed in water. The units can be manufactured and stored on pallets ready for deployment at short notice, or manufactured locally. The unused units are lightweight and fully stackable lid-in-lid and bowl-in-bowl.

Typical applications include:

• Refugee camps

• Slums and shanty towns

• Undeveloped rural communities

• Armed Forces on deployment

• During disruption of established sewage systems - floods, hurricanes, earthquakes, bush fires, any interruption of water supply

• Temporary evacuation of residents to facilities with inadequate numbers of toilets

• Alternative to chemical portable toilets

• Festivals, camp sites, wilderness expeditions

Many new sanitation systems provided for poor communities fail soon after first installation. Often, inadequate consultation of users was made, and with no immediate benefits being apparent, misuse results. Maintenance is neglected, rendering the units unpleasant and ineffective and then populations revert to their previous habits.

The benefits of this invention may be summarised as follows:

• Improved health due to cleaner water and surroundings

• Reduced pollution, less water treatment needed

• Restores fertility, humus levels and structure of soils

• Utilises waste products from developed world

• Generates employment in manufacture and distribution

• Valuable end product to sell to farmers and growers

• Give all ages dignity, safety and clean living conditions

• Reduces need for new water borne sewage systems

• Could generate income for users and processors

• Locks carbon into soil - so helps reduce climate change

• Reduces global reliance on artificial mineral fertilisers

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.




 
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