Field of the invention

The present invention relates to a toilet system, as well as to a toilet bowl for use in a toilet system.

Background of the invention

Conventional toilet systems dispose of human waste by using water to flush the waste from a toilet bowl through a drainpipe to another location. The drainpipe is formed in one of various shapes (e.g. S-bend, U-bend, J-bend or P-bend) to prevent sewer gases from passing from the drainpipe back to the bowl. High volumes of flushing water are required by a conventional toilet, such as 4.5-6 L per flush, so that the total daily water consumption for flushing the toilet ranges between 40-50 L. In fact, a flushing volume of 4.5-6 L is unnecessarily high for liquid waste, yet may be insufficient for solid waste.

Various toilet system improvements have been proposed. One model saves water compared to the conventional toilet by using two buttons, each of which causes a different flush volume to be discharged: a "big flush" or a "little flush" as required. This system was designed initially for drought-prone Australia, and now it is a popular water-saving toilet all over the world. Compared to a conventional toilet, water consumption can be reduced by 65%, although the volume of water may still be insufficient to evacuate solid waste.

Another advanced toilet system, in common use in trains or airplanes, uses a vacuum and water in combination to remove the human waste. Such systems use only 1-2 L of water per flush. The toilet system includes a "valve closet" which has a valve or flap at the exit of the bowl with a water-tight seal to retain a pool of water in the pan. When the toilet is flushed, the valve is opened and the water in the pan flows rapidly out of the bowl into the drains, carrying the waste with it. However, current vacuum flushing toilets incur high maintenance cost. None of the types of toilet systems described above are well-adapted for easy treatment and easy application of the wastewater produced. Although urine makes up less than 1 % of all wastewater, it contributes the bulk of nutrients in wastewater: 85% of the nitrogen and 50% of the phosphorous. Conventional toilets dilute the urine with large amount of flushing water. The flushing mechanism renders the nitrogen and phosphorus recovery process unnecessarily inefficient.

Recently, a source separation toilet (No-mix toilet) has been proposed which diverts urine and treats it separately from the other wastewater streams. The separate collection of urine would permit the construction of smaller wastewater treatment plants, designed to optimize the degradation and the retention of dissolved and particulate organic matter. The separation toilet model uses 0.3-0.5 L water for urine flushing (yellow water) and 2.5-3 L for faeces (brown water). This technology is well accepted in European countries. However, the separation toilet model faces a number of difficulties which include urine-pipe blockages, insufficient flush and landing of urine or faeces in the wrong compartments.

Summary The invention aims to provide a new and useful toilet system, and particularly one addressing at least one of the problems mentioned above.

In general terms, the invention proposes that a source separation toilet has a toilet bowl with a separation ridge to separate urine from faeces. The ridge divides the bowl into a front portion (urine compartment) for receiving urine and having an outlet, and a rear portion (concave area) to receive faeces and paper. The concave area can be selectively put into communication with a vacuum source for vacuum evacuation. A flushing mechanism is provided for discharging a selected volume of water into the bowl under the control of a control system operated by a user of the toilet.

The diverted urine may be removed by gravity after flushing a relatively small amount of water (e.g. 0.2-0.3 L of water per flush). The faeces is removed by discharging water also (but typically only 0.8-1 L of water per flush) during vacuum evacuation.

This means that the average water consumption per flush can be very low. Compared to 4.5-6 L water per flush in conventional toilet, preferred embodiments of the invention consume only 0.2-0.3 L water per urine flush and 0.8- 1 L for faeces evacuation. The total water consumption can thus be reduced by up to 90%, resulting in a significant cost saving. In comparison to a conventional vacuum toilet, the maintenance cost is very low. This is because the vacuum flush is generally used only once per day per user, after defecation. In a conventional vacuum toilet, people flush the toilet after urination also (frequency 5-10 times per day). Thus, in embodiments of the present invention, the frequency of applying the vacuum lower, resulting in lower maintenance cost.

The urine compartment may have a flat-bottom which helps to provide sufficient space for urine to collect before being drained away. The outlet of the urine compartment is collected to an "S"-shape urine pipe which can store enough water to form an odour trap permitting the passage of gasses only in the exit direction. The urine pipe is made from engineering plastic. Suitable materials are HDPE (high density polyethylene) and PVC (polyvinyl chloride). Compared to metal pipes, plastic pipe are less subject to crystal formation in the surface of the pipe. The size of the urine pipe is large enough to avoid clogging. A plastic lip may be provided in the urine outlet, for preventing materials such as tissue or hair from entering the urine pipeline, and thereby avoiding pipe clogging.

The collected urine can be further treated for nutrients recovery (which will be efficient because the dilution caused by the toilet system is so low), while the rest of the wastewater is easily treated in a wastewater treatment plant.

The concave area of the toilet bowl is preferably connected to the vacuum source with a vacuum valve. The vacuum valve is a valve which can be forced into the closed position. For example, it may be a valve which is biased into the closed position by a spring, but can be controlled to open. A horizontal pipe may be provided, such as beneath the concave portion of the bowl, to connect the concave portion of the bowl with the vacuum valve to ensure good performance of vacuum evacuation system. Advantageously, the concave portion of the bowl is formed with a curved profile (e.g. as viewed in cross-section) extending substantially from the top of the ridge rearwardly as far as the entrance to the conduit to the vacuum source, in contrast to the sharp edge of the compartment used in conventional vacuum toilets. This was motivated by laboratory research by the present inventors which showed that the curved profile prevents the embodiment being spoiled with faeces after defecation.

The curved profile also produced a larger effective faeces receiving area. With a larger receiving area, the faeces can drop into water pool and be flushed away easily.

Furthermore, in contrast to a conventional vacuum toilet, embodiments of the present invention have a larger hole to accept faeces. Whereas in a conventional vacuum toilet the diameter of the hole is around 5 cm - which is the same diameter as the pipe leading away from the bowl - in preferred embodiment of the present invention the drainage opening (i.e. the upper surface of the pool) has a cross section with maximum orthogonal directions of at least 8cmx5cm. Note that this is not directly related to the size of the pipe which is fed from the pool.

In addition to that, unlike in a conventional vacuum toilet, in embodiments of the present invention an elevated pool of water is provided so that the faeces can directly drop into the pool instead of the toilet bowl.

The flushing mechanism of the toilet may be provided with multiple water channels. A first of these channels is a urine flushing channel which directs water only to the urine compartment. The other channel distributes water in the whole toilet bowl.

Due to its advanced characteristics, the present source separation toilet is environmental friendly and offers design flexibility. Whereas a conventional toilet system only allows gravitational transportation of human waste, the toilet bowl of the present invention is attached to a vacuum force and makes use of force generated by the vacuum. This means that the pipes can be narrower than in a conventional system, offering increased flexibility during the installation. The toilet system is suitable for installation in high-density residential and commercial urban areas where space scarcity is a major concern. A centralized vacuum pump can serve a high-storey building or shopping complex saving pipe construction cost. Furthermore, the toilet system can be used in hospitals and medical centers where pharmaceutical residues are found in human urine. The diverted urine can be easily treated in order to reduce certain eco-toxicity before discharge to the environment.

Brief description of the drawings An embodiment of the invention will now be described with reference to the drawings, in which:

Fig. 1 is a cross-sectional side view of a toilet system which is an embodiment of the invention;

Fig. 2 is a top view of the embodiment of Fig. 1 ; and Fig. 3 is an enlarged view of a portion of Fig. 1 , illustrating a urine compartment and a ridge.

Detailed description of the embodiment

Referring to Fig. 1 , a first embodiment of the invention will be explained. The embodiment is a source separation toilet illustrated in cross-section in Fig. 1. The embodiment includes a toilet bowl 1. The toilet bowl 1 has a first portion 2 ("urine compartment") for receiving liquid waste such as urine, and a second portion 3 ("concave area") for receiving other waste (faeces and paper) and having a concave surface. A ridge 12 is positioned between the urine compartment 2 and the concave area 3. The ridge 12 is for separating the human waste to different streams. The urine compartment 2 is for urine, and the concave area 3 for the other waste. As described below, the urine compartment 2 is in communication with a urine pipe 4 having an S-shaped configuration. The urine pipe 4 is in connection with first drainage system for receiving urine.

At the lowest part of the concave area 3 is a drainage opening 6 which is in communication with a small diameter horizontal pipe 8. Typically, if the pipe 8 has a circular cross-section, its diameter is about 5cm (e.g. in the range 4cm to 7cm). At the end of the horizontal pipe 8 furthest from drainage opening 6 is a vacuum valve 9 connected to a second drainage system (not shown). The second drainage system includes a vacuum source for sucking fluid along the horizontal pipe 8 when the vacuum valve 9 is open. Optionally, the second drainage system may be connected to multiple toilets of the kind shown in Fig. 1 , so that a single vacuum source may provide suction force to each of them. A pool of water 7 is located at the bottom of the concave area 3, and prevented from running away by the vacuum valve 9. Advantageously, the drainage opening 6 (which may be considered as the upper surface of the pool) has maximum orthogonal dimensions of at least 8 cmx5 cm.

Fig. 2 is a top view of the toilet bowl 1. It shows that at the centre of the portion 2 of the bowl 1 is a urine outlet 5 consisting of a horizontal surface with a number of vertically-extending through-holes formed in it, so that the portion 2 of the toilet bowl 1 is in communication with, the urine pipe 4. The outlet 5 is designed for easy cleaning and clogging removal. Fig. 3, which is an enlarged view of a portion of the cross-section of Fig. 1 , shows this clearly, and illustrates the ridge 12 which divides the portions 2, 3 of the bowl 1. Optionally, the urine outlet may be provided with a plastic lip (not shown) for preventing tissue or hair entering the urine pipe 4. The ridge 12 is high enough that the portion 2 of the bowl 1 can accumulate at least 100 ml_ liquid before it is discharged into urine pipe 4 through the outlet 5. The height of the ridge setting may for example be approximately 2 cm. The side of the ridge 12 which faces towards the concave area 3 of the toilet bowl is formed with a slope to assist the cleaning of the concave area 3. The distance between the ridge 12 and the front edge of toilet bowl 1 on the side of the urine compartment 2, should be sufficient in order to avoid urine spitting into the concave area 3.

The flushing mechanism of the toilet is controlled by multiple buttons 11 (or in other embodiments by a single button which can be moved in multiple different ways). The user can press the buttons selectively, according to the use made of the toilet, to discharge the appropriate amount of water. The flushing mechanism includes multiple water channels which rest within a housing 14 positioned beneath the toilet seat.

A first water channel is provided by a first hose 13, and when this is operated by a respective one of the buttons 11 , it discharges enough water for a small flush (0.2- 0.3 L), only into the urine compartment 2. After flushing, the yellow water is discharged by gravity through the outlet 5 into the urine pipe 4. Because the urine pipe 4 has a small "S" shape, water is retained within it, in order to prevent sewer gases from passing along the urine pipe 4 into the urine compartment 2. By this method, the urine odors are prevented from returning to the toilet bowl 1 and the user is protected from noxious odors. For faeces flushing (big flush), the user presses another of the buttons 11 , and this causes a second hose 10 to discharge water into the whole toilet bowl 1. The amount of water (e.g. 0.8-1 L) is sufficient to clean the concave area 3. The vacuum valve 9 opens and the water flows rapidly from the bowl 1 into the second drainage system, carrying the fecal material and paper with it. The pressure difference between the bowl and the internal drainage system is regulated by the vacuum valve.

The concave area 3 of the toilet bowl 1 is designed with curvature at its edge, in contrast to the sharp edge of the faeces compartment in a conventional vacuum toilet. This enlarges the effective receiving area compared to a conventional vacuum toilet, since essentially the whole of the area to the right (as viewed in Fig. 3) of the top of the ridge functions as a collecting area. With a larger receiving area, the faeces can drop into the pool of water 7 and be flushed away easily by opening the vacuum valve 9 and allowing the vacuum to suck the material away. One of the buttons 11 controls both the hose 10 and the vacuum valve 9. Specifically, it causes a discharge for the hose 10 for a first predetermined period, and for the vacuum valve 9 to open for a second predetermined period overlapping with the first predetermined period. The vacuum valve 9 closes before the hose 10 stops discharging, so that the pool 7 is formed. After the fecal material is removed the vacuum valve 9 is closed and some water remains in the toilet pan to provide a pool 7. The depth of the water pool 7 is more than 6 cm in accordance with international regulations on toilet design. The water pool prevents fecal material becoming adhered to the surface of the toilet bowl.

The toilet bowl 1 can be made of many different materials, such as ceramic, gypsum plaster, stainless steel or a even synthetic polymer (such as cultured marble).