WO1986007617A1

WO1986007617A1 - Method at water supply and sewerage system and system for water supply and sewerage

Info

Publication number: WO1986007617A1
Application number: PCT/SE1985/000259
Authority: WO
Inventors: Rolf T:Son Nordell
Original assignee: Nordell Rolf T Son
Priority date: 1983-12-23
Filing date: 1985-06-20
Publication date: 1986-12-31
Also published as: SE450017B; SE8307144L; SE8307144D0; EP0227657A1

Abstract

A method at water supply and sewerage systems where purified water is supplied via one or several supply places (1) for waste etc., which water assists in the removal and transport of supplied waste from the place of supply, and where the resulting wastewater is purified. The method is especially characterized in that the wastewater is purified to a limited extent and recycled to the supply place(s) in a substantially closed and very local system. The invention also relates to a water supply and sewerage system for carrying out the method.

Description

Method at water supply and sewerage system and system for water supply and sewerage

This invention relates to a method at water supply and sewerage systems where purified water is supplied in one or several supplyl places of waste etc., which water assists in the .removal and transport of supplied waste from the place of supply, and where the resulting wastewater is purified.

The invention also relates to a system for carrying out the method, viz. a water supply and sewerage system. The traditional water supply and sewerage technology has been developed in countries with good drinking water supply and an econoiηy sufficient to allow the consumption and purification of about 250 litres per person and day. WC has been the sanitary installation, which has consumed most of the water. In later years, however, the consumption in WC has been reduced from 10-12 litres to about 6 litres per flushing. Experiments are at present being carried out to additionally reduce^'"the amount of flushing water while at the same time observing that the main system requires to be washed clean. Another problem in'water supply and sewerage technology is the installation of sewers with sufficient inherent fall to be self- cleaning. This implies high installation costs, especially when the sewers are laid at-great depth and particularly in rock.

A further problem is to adapt the water supply and sewerage system to the cycle of nature, so that the wastewater is purified and nutritients and water can be utilized by the vegetation, and infectious matter is not spread. Especially necessary sewage treatment plants, elevated storage tanks and distribution net-^' works have been so expensive, thatbuilt-up areas have been adapted to the water supply and sewerage system. Old built-up areas can in many cases be connected to a water supply and sewerage system only with great difficulty or at high costs.

As at least half of the world population live under straitened circumstances, and the water supply in many places is restricted, the water supply and sewerage technology applied in the industrial¬ ized countries scarcely can be utilized in the developing countries. Corresponding conditions prevail in areas of the type refugee camp.

The present invention relates to a method and a system for the aforesaid object, which render possible substantial, savings in respect of water consumption, piping costs, recoverage of valuable fertilizers and water for artificial irrigation.

Mechanical energy is hereby used to.a certain higher extent, and the purification process takes place in the area to be served by the water supply and sewerage system, in order to simplify the transport of wastewater, reduce the exposure hazard and render recovery poss¬ ible. A minimum of piping is required, and for the distribution of wastewater a circulation pump is used instead of, as normally is the case, a great amount of flushing water, which normally has the quality of clrinking water. As the wastewater is subjected to purification, substantial savings can be made due to rapid and simple pipe laying.,The installation work does not require long- -time training, and the entire water supply and sewerage system can be established in a very short time, for example some weeks, and not several years, as normally is the case. The invention also -renders it possible to actively combat the increased exposure hazard, which arises when new comπunities grow at a rate too high to permit the expansion of necessary conduit systems for electric¬ ity, water etc. The present invention, thus, relates to a method at water supply and sewerage systems,where purified water is supplied in one or several for supply of waste etc., which water assists in the remov¬ al and transport of supplied waste from the place of supply, and where the resulting wastewater is purified. The method is especially characterized in that the wastewater is purified to a limited extent and returned to the supply place(s) in a substantially closed and very local system.

The invention also relates to a water supply and sewerage system, (Comprising one or several supply places for waste etc., to which purified water is intended to be supplied and to assist in the re¬ moval and transport of supplied waste from the supply place, where a sewage treatment plant is provided for purifying the resulting waste- water.

5 The water supply and sewerage system is especially characterized in that said sewage treatment plant is capable to purify, the wastewater only to a limited extent, and that the said sewage treatment plant and supply place(s) constitute the main part of a substantially closed and very local water supply and sewerage system, where means are provided 0 to recycle the purified water to the said supply place(s).

The invention is described in the following in greater detail with reference to an embodiment thereof and to the accompanying drawings, in which Fig. 1 is a schematic view of a first embodiment of a water supply and sewerage system according to the invention shown by way of 5 a vertical section, Fig. 2 is a schematic view of a first embodiment of a recipient according to the invention constituting the main part of

^• a supply place for waste etc., which recipient fs shown by way of a ver¬ tical section A-A according to Fig. 3, Fig. 3 is a section B-B accoVding to Fig. 2 , Fig. 4 is a schematic view of a vertical section through an 0 embodiment of a sewage treatment plant according to the invention, Figs. 5 a~c show schematically parts of three different irrigation systems seen in an obvious way, Fig. 6 shows schematically a second embodiment of a water supply and sewerage system according to the in¬ vention^', shown by way of a vertical section, Fig. 7 shows a second embodi- 5 meπt of a recipient constituting a part of the system according to Fig. 6 seen from above in Fig. 6, Fig. 8 is a perspective view of a part of the system according to Fig. 6, Fi g. 9 shows schematically a system substan¬ tially according to Fig. 6 where the system is intended to be installed in a two-storey building, Fig. 10 shows schematically a third embodiment 0 of a water supply and sewerage system according to the inven.ion, shown by way of a vertical section, Fi g. 11 shows schematically an arrangement comprising several recipients arranged in a serie and Fig. 12 shows sche¬ matically a view over two blocks in which a system according to the in¬ vention is provided. 5 In Fig. 1 the numeral 1 designates a supply place for waste which com^¬ prises a recipient 2, which at the embodiment shown comprises a plu¬ rality of toilet seats. The numeral 3 designates a supply pipe for puri- fied water, by which supplied waste etc. is intended to be removed and transported from the recipient via a sewer ^<■.. The said recipient 2 comprises a flushing trough 5.

The numeral 6 designates a sewage treatment plant comprising at least one sedimentation tank 7_. into which the sewer 4 opens, and which is capable to separate sludge etc. from the wastewater. The numeral 8 designates a pumping installation for puπping^'water from the tank 7 to the active part 9 of the sewage treatment plant while increasing substantially the potential energy of the water. The said active part preferably is of the type bacterial bed with act¬ ivated sludgje. Water having passed through the active part and pur¬ ified thereby is intended to be taken ou£ preferably via a distrib¬ ution tank 10, to be recycled a.o. to said supply place 1, where, of course, several supply places 1 can be provided. According to a preferred embodiment, a buffer tank 11 for sedimentation is provided, to which tank water from said distribution tank 10 is intended to be conducted. .Primarily excess water,preferably stored in said buffer tank 11, is intended to be utilized for irrigation, for which purpose an irrigation system 12 is connected to the water supply and sewerage system.

According to the invention, the sewage treatment plant 7-11 is capable to purify the water only to a limited extent. The sewage treatment plant and the supply place(s) according to the invention constitute the main part of a substantially closed and very local water supply and sewerage system, which is intended to be installed in a very simple and rapid way.

The recipient according to Pigs. 2 and 3 ccπprises at its bottom portion 13 a substantially circular and horizontal collecting and flushing trough 5, which at least at its peripheral portion 14^' com- prises a covering upper side 14 with supply openings 16, at this embodiment toilet seats lb. Via at least one supply pipe 3 waste- water purified in the sewage treatment plant 6 is intended to- be supplied to the trough 5_. so tliat a whirl 5' flushing the trough is formed. At the embodiments shown in Figs. 1 and 2 this is effected in that the water is supplied substantially tangentially at an in¬ take 17 located at the periphery of the trough. The wastewater form- ed in the

5 is drained off via the sewer 4 from an outlet 18 in the bottom 19 of the trough. The numeral 20 designates a relative¬ ly sparse filter for primary separation of iarge waste products.

About the trough 5 preferably a casing 21 is provided, which coπpris- es a space 23, which is formed above the trough by means of walls 22 and open or partially open toward the trough. 24 designates a chimn¬ ey ^'for ventilating the trough and the space 23. At each supply open¬ ing 16 a defined space 26 is formed by means of partitions 25 ad¬ joining the space 23 and extending substantially radially, and an outer wall enclosing the casing and extending in circumferential direction is provided with doors 27, marked in Fig. 3_ so that each space 2β can be opened and closed.

At the embodiment of a sewage treatment plant shown in Fig. 4 a sedimentation tank 7 and a buffer tank 11 are designed as a pref- erably substantially axialsymmetric unit, where the tank 7 extends outwardly about the tank 11. A sewer 4 opens at the upper portion

28 of the tank 7 - A sucking pipe 30 provided with filter connects the tank 7 and said pumping installation 8, preferably at the end

29 thereof located in the upper portion of the tank 7. The pumping installation comprises, schematically shown, a pump, for example a centrifugal pump, by which waste water is intended to be sucked from the tank 7 and pumped up to an upper portion 31 of the active part of the sewage treatment plant 6. The potential energy of the water is intended hereby to be increased, preferably substantially. At this shown preferred embodiment the active part, as mentioned, consists of a bacterial bed 9 with activated sludge. A pipe 32 from the pumping installation 8 feeds a distributor device 33 which, for example via a rotary arrangement, distrib¬ utes water over the upper surface of the bed for causing the water to pass down through the bed. At the bottom 3^ of the bed which comprises apertures a.o. for the intake of air,, preferably via natural draught, a collecting trough 35 is located, from which the water flows down into the distribution tank 10, as shown in Fig. 4. From the tank 10 one or several pipes 3 extend to recycle pur- ified water to one or several supply places 1. In the tank 10 a a first pipe 6 projects vertically upward at a certain distance from the bottom 37 of the tank, so that water can be supplied to the pipe 36 only from below in connection to said bottom 37. SettL-- led sludge 38 is intended thereby to follow along with the water. In the pipe 36 a second pipe 39 is located, via the upper opening 40 of which water having arisen in the pipe 36 is intended to be drained off from the tank 10 and via the pipe 39 be supplied to the buffer tank 11, in which the water is intended to be stored, and in which sludge l following along with the water is intended to settle.

42 designates a pipe for excess water in the tank 11 which via a spillway overflow in the tank 11 is intended in pipes 42 to be supplied to an irrigation system 12, which can vary in scope and design. The water can be supplied to the area to be irrigated in a substantially known manner, for example through a subsurface filter, Fig. 5a, resorption, Fig. b or infiltration, Fig. 5c, or different combinations of the same. Screening gulleys 43 prefer¬ ably are provided in an adequate number in the system. •

In Fi ^. 6-9 an eirbodiment of a water supply and sewerage system according to the invention is shown, where the system is of a particularly compact design and has no proper piping between the sewage treatment plant and the supply places 1. The said supply places 1, at least one of them, is connected to the sedimentation tank 7 of the sewage treatment plant 6. Each recipient 2 consists of an oblong trough 44 or the like projecting from the tank 7₃ which trough at its upper side 45 comprises toilet seats lβ and at its bottom 46 slopes toward the tank 7 for providing a fall. 3 designates, as before, a supply pipe for water purified in the sewage treatment plant 6, by which water the trough 44 is intended to be flushed where the pipe 3 enters the trough 44 at the trough end remote from the tank.

At the embodiment shown in Figs. 6-9 the sewage treatment plant, by way of example, is located centrally in a building 47, marked by dashed line, and said recipients 2 are partially built-in. 48 designates tap sinks comprised in the trough and located outside the building 47. The arrangement in Figs. 6 and 7 can be extended in different ways. Means 9, for example, for freshwater, entirely pure water, can be provided in connection to the supply place. Of course, one or several, for example four, as in Fig. 8, supply places 1, troughs 44, can be arranged in connection to the tank 7.

The tanks 7, 11 and recipients 2 are intended to preferably partially be sunk into the ground, as indicated by the ground level 50 in Fig. 6.

The system according to Figs. 6-9 advantageously can be utilized at the erection of buildings with two or more storeys, as shown schematically in Fig. 9- The bed 9, or corresponding device, is located on an upper plane, and the tanks 7, 11 on a lower one. Sewage from -recipients 2 located on intermediate planes, for example the upper ones in Fig. 9, is supplied to the tank 7 by means .of pipes 51 or the like. In Fig. 10 a system is shown in which the water is administered in a slightly different way compared to in the system according to Fig. 1. Thus, in Fig.- '10 more than one active^'part 9 is meant to be provided. Thus, a distribution tank 10' is provided to which water from the sedi¬ mentation tank/-s 7 is meant to be pumped and from which water is meant to be distributed to the active parts 9 provided via tubes 3'. In Fig. 10 one active part is shown. From the active part 9 the water, after it has been purified as described earlier, is brought to a recipient 2 as shown in Fig. 10, which recipient very well may constitute a unit to¬ gether with the active part 9. The active part 9 may of course serve more than one recipient 2 as indicated by the pipe 3 in Fig. 10.

As shown in Fig. 11 one pipe 3 may provide several recipients 2 with wate the recipients 2 being arranged e.g. as shown in Fig. 11, i .e. in a seri e.

In Fig. 12, showing two blocks 52,53, a possible distribution of reci- pients 2 are shown. In the example each recipient 2 is used by eight houses 5 , the pipes 3,4 for the recipients being placed on the border 5 between properties 54,54' . As can be seen, even at very complicated bloc structures it is possible to arrange a quite simple "pattern" of reci¬ pients. Communication area 5 may be provided for certain households, a shown in Fig. 12. '-.Usi QCJ a pattern e.g. according to Fig. 12 more recipients 2 may easily be provided so that the amount of households per recipient decreases.

The method as well as the mode of operation of the system according to the invention should have become apparent from the aforesaid.

The water supply and sewerage system, thus, comprises a local compact sewage treatment plant and one or several supply places for waste etc. connected to the sewage treatment plant, which system in its entirety is intended to be very local and have short piping distances between the supply places and the sewage treatment plant. In the sewage treat¬ ment plant the water is purified to a limited extent and recycled to the supply places as flushing and transport medium in a substantially closed system, whereby the demand for purified water for the purpose here concerned is reduced to a very high degree. The function and the method are described in the following substantially with reference to the embodiment shown in Figs. 1-4. The basic function, of course, is the same as at the embodiment shown in Figs. 6-11.

In the recipient at each supply place efficient flushing takes place for removing supplied material by means of the whirl arrangement 5' in the trough 5. Water etc. from the trough is transported in pipes 4 to the tank 7. The pipes 4 are laid with fall toward the tank 7. The pipes 4 as well as other transport conduits, a.o. pipes 3, preferably are laid subsoil to prevent exposure hazard. Owing to the short dis¬ tances in the water supply and sewerage system, the pipes 4 laid with fall do not give rise to inconvenience, for example in the form of deep trenches etc. The primary separation of coarse solid substances takes place already in the recipient by means of the filter 20. Additional separation of sludge also occurs mainly in the tank 7 and tank 11 by sedimentation.

The water-pumped from the tank is oxygenated in the bacterial bed 5, and waste substances transported with the water are degraded. Solid substances in the system are degraded continuously by the water thus "activated", which is recycled. Thus, substances separated in the re¬ cipient and sludge settled in the tanks are degraded. The nutritients in the sludge etc. which at the degradation have assumed a state suitable for their use, are utilized for cultivation. The potential energy of the water increased by the pumps is utilized for recycling the water to the places of supply in such a manner) that pipes 3 without fall are used. In this step, thus, the demand for deep trenches is entirely eliminated, and the pipes are laid only slightly beneath, ground level.

The water supply and sewerage system according to the invention pre¬ ferably comprises control possibi lities in respect of a.o. the pro- portion of recycled water. The inner pipe 39, for example, can be designed so as to be lifted and lowered, whereby the flow to the tank 11 , for example, can be stopped completely. Hereby all water is recycled, which is a suitable measure- at flooding risk etc.

The system requires a certain maintenance, bcth daily and periodically. Sludge, for example, must be removed periodically and, therefore, places where sludge accumulates, for example at the recipient and the tanks 7 and 11 , must be easi ly accessible, so that the sludge can be removed with simple means.

As should have become apparent from the aforesaid, important features in the method and water supply and sewerage system according to the invention are, that partially purified water is used in a- local com¬ pact system, that mechanical energy is supplied (through the pumping

installation) , and that the water is oxygenated immediately after the supply places and continuously within the circuit in the system, so that a very high degradation of waste products per time unit is ob¬ tained. Due to the early separation of coarse solid substances, pipes with small dimensions can be used. The main system can to a large ex¬ tent be assembled of prefabricated hoses. The said separated substan¬ ces, if not removed manually, successively are degraded, because the recycled water from the sewage treatment plant rtakes along oxygen and activated sludge. For primary separation at the embodiment shown in Figs. 6-11 a bar screen or the like can be positioned between .the reci- pi ent 44 and tank 1.

The energy supply for the pumping installation in a system of normal size is low, of the magnitude 5"10 kW per person, and can be .co¬ ordinated with electric lighting etc. in a simple way. The electro¬ mechanical part is very simple and for a community of 1000 persons can be limited to about 15 HP.

As should have become clear from the aforesaid, the method and the water supply and sewerage system according to the invention offer several advantages over the known art. For example, all of the water is used, and the demand of pure water is very low. The system can be installed in a simple, inexpensive and rapid way. Most of the parts comprised in the system can be designed independently of the place of installation and be prefabricated in long series^'.^" The nutritients in the waste are recovered. The exposure hazard is restricted due to thelimited closed system.

The invention has been described above with reference to one embodi- ment. Several more embodiments, variants and minor alterations, of course, can be imagined without abandoning the invention idea.

It is possible,as mentioned, to connect a plurality of supply places to one sewage treatment plant. For a great number of inhabitants seve¬ ral water supply and sewerage systems can be installed, whereby the sensitivity for breakdowns decreases.

The recipients, further, can be varied, for example in such a way, that the recipients are provided with shower and .wash-bas i n, as indicated with reference to Figs. 6 and 7, where in an obvious manner the system is suppl ied with water of washing water quality and where the washing water used is supplied to a recipient 2.

It also is imaginable that recipients, for example according to Figs. 1-4, are arranged on several storeys. The water supply and sewerage system may also comprise combinations of recipients 2 of different design. Each supply opening can be designed as a combined toilet-tap sink 43, as shown in Fig. 3. At a slightly further developed design, each household unit can be provided with a water seal, which requires a very small flushing amount. The recipient can be built-in centrally in a building, so that each supply opening and space 26 can be reached at only by one household from the dwelling space. In this case a suitable number of spaces should be less than eight, as shown in Fig. 3, for example four.

Embodiments ; of sewage treatment plants other than such with one bac¬ terial bed can be imagined. For example, as active part 9 a so-called biorotor can be imagined. Oxygenation can also be imagined to be effect¬ ed by the injection of air. The pumping installation may also comprise more pumps, for example in the sewers 4, thereby reducing additionally the demand for con¬ duits wi th fal 1.

It also is possible to imagine embodiments where means, for example electric ones, are provided for heating at least the^'bed 9 or the like, whereby, for exampl e, -sa id means can be adjusted to the cli- mateϋn northern countries, in iat the active part of the sewage treatment plant can be kept at a sui tabl e. temperature.

The isvention, thus, must not be regarded restricted to the variants and embodiments set forth above, but can be varied within the scope of the attached claims.

Claims

Cl aims

1. A method at water supply and sewerage systems where purified wa¬ ter is supplied at one or several places of supply for waste etc. , which water assists in the removal and transport of supplied waste from the place of supply, and the resulting wastewater^" is purified, c h a r a c t e r i z e d i n that the wastewater is purified to a limited extent and recycled to the supply place(s) (1) in a substan¬ tially closed and very local system.

2. A method as defined incJaim 1 , c h a r a c t e r i z e d i n that each supply place (1) comprises a recipient (2) with a collecting and flushing through (5,44), to which purified wastewater is supplied, and that the wastewater from the trough (5,44) is supplied to at least one sedimentation tank (7) for separating sludge from the wastewater, and from said tank (7) is pumped, while increasing substantially the potential energy of the water, and brought to the active part (9) of a sewage treatment plant, which active; ^• part preferably is of the type bacterial bed with oxygenation of activated sludge, and from the active part (9) of the sewage treatment plant purified water is taken out and, preferably via a distribution tank (10), recycled to the said recipients (2) by utilizing the potential energy of the water.

3. A method as defined in claim 2, c h a r a c t e r i z e d i n that water is pumped to a distribution tank (10¹) from which water is distri¬ buted to at least two active parts 9.

4. A method as defined in claim 2 and 3, c h a r a c t e r i z e d i n that said purified wastewater is supplied to the collecting trough (5) whi le developing a whirl (5¹) flushing the trough (5).

5. A method as defined in claim 2, 3 or 4, c h a r a c t e r ! -z e d i n that said recipient is connected to the sedimentation tank (7). whereby a very compact system is obtained.

6. A method as defined In claim 2, 3, 4 or 5 , c h a r a c t e r i z e d i n that several recipients (2) are provided in one building or the like and on more than one storey.

7. A method as defined in claim 2, 3, 4, 5 or 6, c h a r a c t e r i z e i n that water from said distribution tank is supplied to a buffer tank (11) for sedimentation.

8. A method as defined in claim 7, c h a r a c t e r i z e d i n that water for irrigation by infi ltration or the like is taken pre¬ ferably from said buffer tank (11).

5 9. A method as defined in claim 1 , 2 , 3, 4, 5 , 6, 7 or 8, c h a r a c- t e r i z e d i n that supply places (1) comprise washing and/q,r shower arrangements where pure water, such as drinking water, is supplied.

10. A method as defined in claim 1 , 2, 3, 4, 5, 6, 7, 8 or 9, c h a r a c t e r i z e d i n that the water from the sewage treatment

10 plant (6) is conducted subsoil to said supply places (1) to prevent exposure hazard.

11. A method as defined in claim 2, 4, 5, 6, 7, 8, 9 or 10, c h a r ¬ a c t e r i z e d i n that the proportion of water from the active part (9) of the sewage treatment plant, which water is recycled to the

15 supply place(s) (1), is controlled by devices in connection to the distribution tank (10).

12. A method as def i ned in claim 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 , c h a r a c t e r i z e d i n that primary separation of coarse solid substances is carried out in the recipient (2).

20 13. A method as defined in claim 1 , 2, 3, 4, 6, 7, 8, 9, 10, 11 , 12 or 13, c h a r a c t e r i z e d i n that recipients (2) are arranged in a serie water to the recipients being supplied by means of a common pipe (3).

14. A water supply and sewerage system, comprising one or several supply 25 places for waste etc. , to which purified water is intended to be supplied and to assist in the removal and transport of supplied waste from the place of supply, and where a sewage treatment plant is provided for puri¬ fying the resulting wastewater, c h a r a c t e r i z e d i n that said sewage treatment plant (6) is capable to purify the wastewater only to 30 a limited extent, and that said sewage treatment plant (6) and supply place(s) (1) constitute the main part of a substantially closed and very local water supply and sewerage system, which comprises means (3) for recycling the purified water to said supply place(s) (1).

15. A water supply and sewerage system as defined in claim 14, c h a r - 35 a c t e r i z e d i n that each supply place (1) comprises a recipient (2) with a collecting and flushing trough (5,44), which is intended to be supplied with purified wastewater, and that said trough (5,44), via sewers (4) for the wastewater produced in the trough or by direct connection, is connected to at least one sedimentation tank (7) capable to separate sludge etc. from the wastewater, and that it comprises a pump installation (8) for pumping water from said tank (7), the water being meant to be supplied to at least one active part (9) of the sewage treatment plant (6) while substantially increasing the poten¬ tial energy of the water before supplying it to said active part/-s (9) , which active part/-s (9) preferably is of the type bacterial bed with oxygenation and activated sludge, and that it preferably comprises a distribution tank (10), via which the purified water is intended to be taken out and recycled to said supply place(s) (1).

16. A water supply and sewerage system as defined in clairri-15, c h a r a c t e r i z e d i n that at least two active parts (9) are provided:.to whi ch water is meant to be supplied from a distribution tank (10^l) to which water from a sedimentation tank (7) is intended to be pumped..

17. A water supply and sewerage system as defined in claim 15 and 16, c h a r a c t e r i z e d i n that the collecting trough (5) is in¬ tended to be supplied with said purified wastewater, so that a whirl (5¹) flushing the trough (5) is brought about.

18. A water supply and sewerage system as defined in claim 15, 16 or 17, c h a r a c t e r i z e d i n that it comprises several re- cipients (2) located in a bulding (47) or the like and on more than one storey.

19. A water supply and sewerage system as defined in claim 14, 15, 16,

17 or 18, c h a r a c t e r i z e d i n that it comprises a buffer tank (11) for sedimentation, to which tank water from said distribu- tion tank is intended to be supplied.

2Q. A water supply sewerage system as defined in claim 14, 15_. 16, 17

18 or 19_. c h a r a c t e r i z e d i n that an irrigation system (12,42) for infiltration or the like is connected to the water supply and sewerage system, and that means are provided for transferring water from the sewage treatment plant to the irrigation system.

21. A water supply and sewerage system as defined in claim 20, c h a r a c t e r i z e d i n that means (42) are provided for transferring water from said buffer tank (11) to the irrigation system.

22. A water supply and sewerage system as defined in claim 13, 14, 15, 16, 17, 18, 19, 20 or 21 , c h a r a c t e r i z e d i n that one or several recipients (2) are provided comprising a plurality of supply openings (16) , which are located above the trough (5,44).

23. A water supply and sewerage system as defined in claims 15, 16,

17, 18, 19, 20, 21 or 22, c h a r a c t e r i z e d i n that it com- prises means for supplying pure water of at least washing water quality to one or several recipients,^' which comprise shower and/or washing basin and w-here the wastewater is supplied to said trough (5,44).

24. A water supply and sewerage system as defined in claim 15, 16, 17,

18, 19, 20, 21 , 22 or 23, c h a r a c t e r i z e d i n that said trough (5) is supplied with purified water from at least one supply pipe (3) substantially tangential ly at an inlet (17) located at the periphery of the trough (5), and that the. wastewater produced in the ^' trough is tapped via a cent ral ly located outlet (18) in the trough bottom (19), and that preferably a relatively sparse fi lter (29) is provided for primary separation of coarse solid substances in connection with said tappi ng.

25. A water supply and sewerage system as defi ned.-i. claim 15, 16, 17, 18,

19, 20, 21 , -22 or 23, c h a r_, a c t e r i z e d i n that at least one recipient (2) is located connected to the sedimentation tank (7) , which recipient consists of an oblong trough (44) projecting from the tank (7).

26. A water supply and sewerage system as defined in claim 19, 20, 21 , 22 23, 24 ^'or 25, c h a r a c t e r i z e d i n that the distribution tank includes a first pipe (36) located vertically and upward projecting at a certain distance from the bottom (37) of the tank (10) , so that water can be supplied to the pipe (36) only from below, and settled sludge_. (3_)is intended to follow along with the water, where a second pipe (39) is pro- vided in the pipe (36), via the upper opening (4?) of said pipe (39) water arisen in the first pipe (36) is^' intended to be tapped and via the second pipe (39) to be supplA&d to said buffer tank (11), and that said second pipe preferably is vertically adjustable, whereby the flow through the pipe (39) can' be controlled, a.o. stopped completely, so that the proportion of water passed to the distribution tank (10) , which water is supplied to the buffer tank (11), can be varied.

27. A water supply and sewerage system as defined in claim 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25 or 26, c h_. a r a c. t e r i z e d i n that it comprises means, for example electric ones, for heating the active part (9) of the sewage treatment plant.

28. A water supply and sewerage system as defined in claim 15, 16, 17, ^'18, 19, 20, 21 ,-22, 23, 24, 26 or 27, c h a r a c t e r i z e d i n that reciip^'eπts (2) are arranged in a serie, a common pipe (3) being provided for supplying water to the rec ients (2).