SEWAGE SYSTEM AND METHOD OF HANDLING WASTEWATER

Abstract: A sewage system has a first source of waste water (10), which discharges heavily polluted water, in the form of a toilet or the like, a second source of waste water (20) of another type, which is adapted to discharge less polluted water, and a network of waste pipes (1). A buffer tank (30) is connected between the first source of waste water (10) and the network of waste pipes (1) for collecting waste water from the first source of waste water (10), and a storage tank (40) is connected between the second source of waste water (20) and the network of waste pipes (1) for collecting waste water from the second source of waste water (20). The sewage system is arranged for common intermittent flushing of waste water into the network of waste pipes (1).

Description: SEWAGE SYSTEM AND METHOD OF HANDLING WASTE WATER Field of the Invention The present invention relates to a sewage system of the type stated in the preamble to appended claim 1. Moreover, the invention relates to a method of handling waste water according to the preamble to appended claim 9. Background Art Current sewage systems conduct, from housing, waste water from toilets, washing-up and washing, drainage water from foundations, and storm water, for example rain water, from roofs and other surfaces, such as streets and parking spaces. Industries also discharge industrial process water. As a rule, waste water and storm water are separated in current sewage systems, where waste water and industrial process water are conducted in a special waste water conduit and the less polluted storm water and drainage water are conducted in a storm water conduit. The waste water is conducted to a sewage treatment plant, where it is treated before being recirculated to a natural watercourse. In the sewage treatment plant, solid heavy particles are separated in settling basins. It is then important for the water to be allowed to be stagnant so that sludge and water can form layers. Biological and chemical purification also take place. Large amounts of polluted water originate from bathrooms and sources of waste water, such as toilets, wash-basins, tubs, showers and, in some cases, also wash- ing machines. With a view to saving water, attempts have been made to use low-flush toilets in existing buildings, which has often caused blocked-up piping, owing to the smaller amount of water in relation to the amount of paper and faeces . Blocked-up sewage systems may cause many problems to the surroundings and to solve these, the piping is flushed. This is a time-consuming, complicated and expensive additional measure and the intended saving of water is reduced or does not occur. For good function with low-flush toilets in a building, the network of waste pipes in the building must as a rule be particularly dimensioned. This means that in many cases extensive and costly reconstructions must be carried out in existing buildings. Moreover many toilets are used as "waste paper baskets", thus causing large amounts of water to be flushed out . Experiments have also been made to take care of waste water from wash-basins, showers etc. and use this water to flush away faeces. US-A-3, 843, 976 discloses a system of this type. A toilet is placed at a first, upper level. In this toilet, faeces are embedded in foam and conducted to a trap which is arranged below a second, lower level. At the second, lower level, a storage tank is arranged inside a widened portion of the network of waste pipes. The storage tank is constructed so that it tilts and empties itself when it has been filled to a certain liquid level. When the storage tank empties it- self, the water is conducted to the pipe bend where any faeces from the toilet are located. This technique, however, requires considerable modifications in the network of waste pipes of existing buildings, which necessitates expensive and extensive reconstructions if this solution is to be used in existing buildings. Moreover, from the sanitary point of view it is not suitable to conduct the faeces to the pipe bend in the sewage system and let them stay there. Summary of the Invention An object of the present invention is to provide water-saving improvements for the handling of waste water. A special object of the invention is to enable saving of water in existing buildings without necessitating extensive reconstructions. According to the invention, these and other objects that will appear from the following specification are achieved by a sewage system and a method, which are of the types described by way of introduction and which besides have the features stated in the characterising clause of claims 1 and 9, respectively. From a first source of waste water, which can be a toilet or the like, comes heavily polluted water. From a second source of waste water, which can be a shower, a wash-basin of the like, comes less polluted water. In connection with the invention, heavily polluted water means particularly that the water comprises sludge- and sediment-forming substances, and less polluted water means that the water comprises relatively smaller amounts of sludge- and sediment-forming substances. The water from the two sources of waste water is collected in a separate tank each, a buffer tank for heavily polluted water and a storage tank for less polluted water. The less polluted water is used for intermittently flushing out the heavily polluted water in the network of waste pipes, which means that it is possible to reduce the total flow of water with no risk of the network of waste pipes being blocked up. In particular, a considerably smaller amount of water can be used in a toilet for flushing. This saving of water gives several advantages since the amount of water that is used and polluted can be reduced. Also the flow of water through a building decreases, which, especially in cold countries, results in saving of energy since it will be a smaller amount of water that takes up and gives off heat when passing through the building. A special advantage is that hot waste water from, for instance, a shower can remain for a while in the storage tank and there emit a large amount of its heat content to the building. By intermittently flushing out the waste water, it is possible to control the direction in which the heavily polluted water is conducted and the direction in which the less polluted water is conducted, which enables an environmentally correct use of the portion of waste in the waste water. This principle can be used for all kinds of waste water treatment, where waste water with different degrees of pollution is generated, but a particularly convenient application is the flushing away of organic waste since this can be used as fertiliser if not mixed with far too chemically polluted waste water. According to the invention, the storage tank and the buffer tank are integrated with the sources of waste water (toilet, wash-basin, shower etc.). For example, in a special embodiment for bathrooms, it is possible to in- tegrate a toilet and a wash-basin into a sanitary unit. From showers, washing machines and like sources of waste water, the water can be conducted to the storage tank in the sanitary unit. For kitchens, a special embodiment, such as a kit- chen unit, can be composed of a first source of waste water, which discharges heavily polluted water, in the form of a waste disposer or like equipment for food waste, and a second source of waste water such as a sink. Such units for kitchens and bathrooms can then be connected to the usual network of waste pipes of the house. By letting the storage tank flush the buffer tank in response to a control signal, good cleaning of the buffer tank is obtained, at the same time allowing the point of time when flushing is due to be controlled. Preferred embodiments are defined in the dependent claims . A simple control signal, which in many cases is convenient, is that the buffer tank is flushed when the storage tank has been filled to a certain predetermined level. To prevent flushing from taking place at unsuit- able points of time, for instance at night when a flushing may wake up neighbours, a valve is advantageously arranged to prevent flushing of the buffer tank. The valve which controls the flushing of the buffer tanks can alternatively also be centrally controlled, which makes it possible to control what kind of waste water is discharged at different points of time. At certain points of time, it is, for instance, possible to empty the buffer tanks and during the rest of the time, it is possible to let excess water from wash-basins and the like flow out into the network of waste pipes. According to a special aspect of the invention, a toilet having a foldable bowl is integrated with a wash-basin. The less polluted water from the wash-basin is collected in a storage tank and the more heavily pol- luted water from the toilet is collected in a buffer tank. The water in the storage tank is used to flush the buffer tank down into the network of waste pipes. The toilet is flushed before and after use. The tiltability and the flushing of the bowl make it easier to empty and clean the toilet, thus making it possible to use a smaller amount of water than in an ordinary toilet. When time-controlling the waste water, it is possible to have, in connection with the building or in connection with a block, a separating unit, such as a gully, which by settling of sludge from the heavily polluted water takes care of organic waste from toilets and other sources for essentially organic waste, such as a waste disposer. Since the buffer tanks are emptied only at predetermined points of time, the water in the separating gully is stagnant for a considerable time, which means that sludge and water will have time to form layers before the next amount of water is flushed to the buffer tank. The amount of less polluted water that is not required for flushing the buffer tanks can in the meantime be conducted past the separating gully so as not to interfere with the layering process therein. The sludge collected in the separating gully can then be used as fertiliser since it comprises practically nothing else than pure organic waste which has not been mixed with chemicals and heavy metals from industrial waste water. The controlling of the flushing can also be adapted in such manner that the public network of waste pipes is utilised correctly. In such controlling, the dimensions of the network can be made smaller since it is no longer necessary to dimension it to manage a "worst-case scenario". Moreover, the controlling renders it possible to adjust the emptying of the buffer tanks with regard to what occurs in the sewage treatment plant. With knowledge about what type of waste water is discharged at certain points of time, the sewage treatment plants can better adjust their purifying processes according to the type of impurities that may be expected to be entrained by the water. For example, separating basins work more satisfactorily if they are allowed to stand for a considerable time. By having a smaller total flow through the sewage treatment plant, it will be easier to give the water in the basins a chance to be stagnant and form layers. Brief Description of the Drawings Embodiments of the invention will now be described in more detail with reference to the accompanying draw- ings . For exemplification, the drawings illustrate a sewage system and the units that are suitably used in such a sewage system. Fig. 1 is a schematic view of how the sewage system can be adjusted to be accommodated in a building. Fig. 2 is a schematic view of how the sewage system in the building is connected to the surrounding network of waste pipes. Fig. 3 shows a sanitary unit in which a toilet and a wash-basin have been joined. Fig. 4 illustrates a sink with an integrated waste disposing unit. Description of Preferred Embodiments A sewage system in a building comprises, with reference to Fig. 1, a first source of waste water 10, in the form a toilet, which discharges heavily polluted water, a second source of waste water 20, in the form of a wash-basin, which discharges less polluted water. The system further comprises a buffer tank 30 for collecting the waste water from the first source of waste water 10, and a storage tank 40 for collecting the waste water from the second source of waste water 20. The water collected in the storage tank 40 is used for intermittent flushing of the water in the buffer tank 30. This can take place, for instance, by the water from the storage tank 40 being conducted through the buffer tank 30, but it may also take place by the buffer tank 30 and the storage tank 40 being connected in parallel to the network of waste pipes 1 and by first the buffer tank 30 being emptied and immediately after that the storage tank 40 being emptied. Fig. 2 shows a building with sources of waste water and a network of waste pipes 1, which conducts waste water from the building to a sewage treatment plant 3, via a separating gully 2. The waste water is conducted in the network of waste pipes 1, to the separating gully 2, in which the water is stagnant so that the water and the sludge therein can form layers so as to allow the waste to be removed. The remaining waste water is then con- ducted in the public network of waste pipes 1 to finally reach a sewage treatment plant 3. Owing to the flushing being time-controlled, the system according to this embodiment makes it possible to separate sludge from waste water in the vicinity of the source without necessitating complete chemical and bio- logical purification at this intermediate step. A sanitary unit 100, which is shown in Fig. 3, is a suitable embodiment of part of the sewage system according to the invention and comprises the main components: a wash-basin 120, a storage tank 140, a toilet 110 and a buffer tank 130. The outlet pipe 121 of the wash-basin is connected to the storage tank 140, in which the slightly polluted water is stored. The toilet 110, which is fold- able, is raised after use and emptied via a discharge duct 111 into the buffer tank 130. The buffer tank 130 is in turn connected to the waste pipe 1 of the house. When the storage tank 140 has been filled above a certain level, a valve (not shown) opens and the water in the storage tank 140 is conducted via a pipe 141 down to the buffer tank 140 which is flushed, and out through the waste pipe 1 of the house. The foldability of the toilet means, among other things, that it takes up a smaller space when not being used. The toilet 110 is raised and lowered by means of a pressure cylinder (not shown) , which is double-acting, uses the pressure exerted by the inlet water and is operated by means of a control valve (not shown) . The water on the idle side of the cylinder, which is pressed out of the cylinder when operated, is used for preflushing and reflushing of the toilet. When the toilet 110 is to be used, it is lowered by moving an operating lever (not shown) which operates the control valve, which opens for inlet water conducted to the pressure cylinder. The pressure cylinder lowers the toilet 110 to its position of use while at the same time the water from the idle side of the pressure cylinder is passed into the toilet 110 for wetting the same. When the user has finished, he moves the operating lever to a closing position. The control valve then instead directs the flow of water to the other side of the pressure cylinder which raises the toilet 110. The water coming from the idle side is also in this case conducted back to the toilet 110. On its way to the toilet 110, the water passes a cylinder 112 which opens a flap 113 which in the normal case covers the opening of the discharge duct 111 to prevent odour from being emitted from the buffer tank 130. This can also be prevented by means of a trap. The water is conducted to the sides of the toilet 110 where it is ejected through flushing nozzles 114. The flushing nozzles 114 cause the water to be flushed down in the toilet 110 at high speed, thereby cleaning the same. Moreover, the water is flushed as a mist into the discharge duct 111, which prevents odour from being emitted from the buffer tank 130. Since flushing and emptying take place when the toi- let 110 is inclined to a certain degree, the contents of the toilet together with the water easily fall down into the buffer tank 130 to remain there for a time. Thanks to the tilting function of the toilet, only small amounts of water are required for flushing. When the toilet is al- most in its uppermost position, a safety lever (not shown) is engaged, which in turn switches the operating lever from the closing position to the neutral position, whereby the control valve closes for the inlet water to the pressure cylinder. The pressure exerted by the water on the flap-opening cylinder 112 disappears, thereby closing the flap 113. To allow the toilet 110 to close the last distance, a pneumatically operated spring (not shown) is arranged to press the toilet 110 and hold it in place until the toilet is to be used the next time. There are at least two advantages of making the toilet 110 foldable; on the one hand the inclination of the bowl facilitates emptying thereof and, on the other hand, the toilet takes up a smaller space. As the wash-basin 120 is used, water flows down through its outlet pipe 121 to the storage tank 140. When the water in the storage tank 140 reaches a certain level, a discharge valve opens and water flows down through a discharge pipe 141 into the buffer tank 130. The jet of water hits the contents of the buffer tank 130 and pushes them to the waste pipe connection 131 and out through the waste pipe 1. Owing to the fact that the less polluted water pushes the more polluted water, an effective flushing of the network of waste pipes is obtained. To prevent the buffer tank 130 from being flushed at inconvenient points of time, the sanitary unit 100 is pro- vided with a flush-blocking means which controls the point of time when flushing is feasible. When the flush-blocking means is in the blocking position, flushing does not take place even if the water in the storage tank 140 has reached the level of emptying. Excess water is instead conducted out of the storage tank 140 through an overflow pipe 143 down to the waste pipe connection 131. If the supply of water to the house is disconnected, it is still possible to flush the toilet 110 a few times, which is carried out as follows. The operating lever is set in the opening position and the toilet 110 is pulled down to the position of use. The water that is available in the pressure cylinder is then pressed out and pre- flushes the toilet 110. The side which would have been the operating side of the cylinder draws in water from the storage tank 140 through non-return valves. In normal supply of water to the building, at least 5 1 of water always remain in the storage tank 140 after flushing. This water can be used to flush the toilet. When the user has finished, he moves the operating lever from the opening position to the closing position and raises the toilet 110. Flushing occurs as usual with water from the idle side of the pressure cylinder. The side which would now have been the operating side also draws in water from the storage tank 140. The above-mentioned pneumatically operated spring (not shown) aids in moving the toilet 110 to its resting position. The toilet 110 can be used and flushed as long as there is any water left in the storage tank 140. This is a great hygienic advantage compared with today' s ordinary toilets which can only be flushed once when the supply of water is disconnected. A kitchen unit 200, which is shown in Fig. 4, is made up of the main components: a storage tank 240, a buffer tank 230, a sink 220 and a waste disposer 210. The sink 220 is of a common type with a single sink or two or more sinks. The waste disposer 210 can be an ordinary waster disposer, but in a preferred embodiment, use is made of a water-actuated pressure cylinder 212 which presses the waste through an apertured plate. In the same way as in the sanitary unit 100, water from the sink (or sinks) is collected in a storage tank 240. After being compressed by the pressure cylinder 210, the food waste is collected in a buffer tank 230. The buffer tank 230 is flushed intermittently by means of the water in the storage tank 240. Juste like in the sanitary unit 100, the flushing can be controlled, for example, by filling the storage tank 240 or by centrally controlling a flush- blocking valve. The kitchen unit 200 essentially corresponds to the sanitary unit 100 and its function can be controlled and adjusted in the same manner as for the sanitary unit 100. The kitchen unit 200 or a variant thereof is above all suitable for use in large-scale kitchens, slaughter hoses, gardeners, or other installations where large amounts of organic waste arise. The sink 220 and the waste disposer 210 or the waste cylinder 212 need not necessarily be interconnected. The sewage system, the sanitary unit 100 and the kitchen unit 200 are examples of convenient constructional solutions which utilise the basic concept of col- lecting heavily polluted waste water in a buffer tank 30, collecting less polluted water in a storage tank 40, and using the water in the storage tank 40 for intermittently flushing the waste water out of the buffer tank 30.

Claims: CLAIMS 1. A sewage system comprising at least one first source of waste water (10; 110; 210) , which is adapted to discharge heavily polluted water, such as a toilet or the like, at least one second source of waste water (20; 120; 220) of another type, which is adapted to discharge less polluted water, and a network of waste pipes (1) , to which the first source of waste water (10; 110; 210) and the second source of waste water (20; 120; 220) are connected, and a storage tank (40; 140; 240), which is connected between the second source of waste water (20; 120; 220) and the network of waste pipes (1) for collecting waste water from the second source of waste water (20; 120; 220) , the sewage system being arranged for common intermittent flushing out of waste water into the network of waste pipes (1) , ch a r a c t e r i s e d in that the sewage system further comprises a buffer tank (30; 130; 230), which is connected between the first source of waste water (10; 110; 210) and the network of waste pipes (1) for collecting waste water from the first source of waste water (10; 110; 210), the storage tank (40; 140; 240) being adapted to be emptied into and flush the buffer tank (30; 130; 230) in response to a control signal, the first source of waste water (110; 210), the storage tank (140; 240), and the buffer tank (130; 230) being joined to an integral unit (100; 200) , and the unit being connected to the network of waste pipes (1) . 2. A sewage system as claimed in claim 1, wherein there is arranged in the network of waste pipes (1) downstream of the buffer tank (30; 130; 230) a separating unit (2), which is adapted to separate impurities from the waste water between the intermittent flushings in the network of waste pipes (1) . 3. A sewage system as claimed in claim 2, wherein the separation occurs by settling of sludge from the waste water. 4. A sewage system as claimed in any one of the preceding claims, wherein the second source of waste water (120; 220) is integrated in the unit (100; 200) . 5. A sewage system as claimed in any one of the preceding claims, wherein the first source of waste water (110) is a toilet. 6. A sewage system as claimed in any one of the preceding claims, wherein the first source of waste water (210) is a food waste treatment unit, such as a waste disposer or the like. 7. A sewage system as claimed in claim 5, wherein the toilet (110) is flushed before use. 8. A sewage system as claimed in claim 5 or 7, wherein the toilet (110) is foldable. 9. A method of handling waste water from at least one first source of waste water (110; 210) which discharges heavily polluted water, such as a toilet or the like, and at least one second source of waste water (120; 220) which discharge less polluted water, ch a r a c t e r i s e d by the steps of: collecting the waste water from the first source of waste water (110; 210) in a buffer tank (130; 230), and collecting the waste water from the second source of waste water (120; 220) in a storage tank (140; 240), joining the first source of waste water (10; 110; 210), the storage tank (140; 240), and the buffer tank (130; 230) to an integral unit (100; 200), connecting the unit (100; 200) to a network of waste pipes (1), commonly flushing out the waste water from the stor- age tank (140; 240) and the buffer tank (130; 230) to the network of waste pipes (1) , and emptying the storage tank (140; 240) through the buffer tank (130; 230) in response to a control signal. 10. A method of handling waste water as claimed in claim 9, wherein the control signal is emitted at pre- determined points of time. 11. A method of handling waste water as claimed in claim 9 or 10, wherein sludge in the waste water is separated from the waste water. 12. A method of handling waste water as claimed in claim 11, wherein the separation occurs by settling.

Inventors: LINDH PAUL D, LINDH, PAUL, D.
Applicants: DUNBRIAR INVESTMENTS LIMITED, LINDH PAUL D, LINDH, PAUL, D.
Application year: 1999
Main classification: E03D5
IPC codes: E03D5, E03F3