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Title:
METHOD FOR PURIFYING SEWAGE WATER
Document Type and Number:
WIPO Patent Application WO/2013/058705
Kind Code:
A1
Abstract:
Method for purifying sewage water from a first water closet (211), comprising the steps: a) bringing the sewage water from the first water closet to a locally arranged collecting vessel (221) for sewage water; b) circulating a gas through the collecting vessel and thereby causing the gas to bring with it a share of the contents in the collecting vessel in the form of evaporated water vapour; c) in a dehumidification step (230,242), causing the said water vapour to condense and collecting the thus condensed water; d) using the condensed water for flushing in a second water closet, which may be the same as the first water closet; and e) removing the slurry which remains in the collecting vessel after the said evaporation from the collecting vessel for further treatment, wherein the gas in the dehumidification step (230,242) is cooled by a heat pump being caused to transfer thermal energy from the gas to a fluid which is circulated in an external loop (243, 244), and wherein the said fluid is caused to heat indoors air or tap water in a building (210). The invention also relates to a device.

Inventors:
JAEMSAE JANNE (SE)
Application Number:
PCT/SE2012/051122
Publication Date:
April 25, 2013
Filing Date:
October 19, 2012
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
JANNE JAEMSAE JJ PRODUKTER AB (SE)
JAEMSAE JANNE (SE)
International Classes:
E03D5/016; C02F1/04; E03D11/11
Foreign References:
US5257466A1993-11-02
US5058213A1991-10-22
JPS63102731A1988-05-07
JP2005131536A2005-05-26
US20010047538A12001-12-06
US5698095A1997-12-16
Attorney, Agent or Firm:
ÖRTENBLAD, Johan et al. (P.O. Box 10198, S- Stockholm, SE)
Download PDF:
Claims:
C L A I M S

1. Method for purifying sewage water from a first water closet (111 211; 311 ; 411 ) , comprising the steps:

a) bringing the sewage water from the first water closet to a locally arranged collecting vessel (121; 221; 321; 421) for sewage water;

b) circulating a gas through the collecting vessel and thereby causing the gas to bring with it a share of the contents in the collecting vessel in the form of evaporated water vapour;

c) in a dehumidification step ( 130 , 139 ; 230, 227 ; 351 ;

460,461), causing the said water vapour to condense and collecting the thus condensed water;

d) using the condensed water for flushing in a second water closet, which may be the same as the first water closet; and

e) removing the slurry which remains in the collecting vessel after the said evaporation from the collecting vessel for further treatment,

c h a r a c t e r i z e d i n that the gas in the dehumid- ification step (230, 242) is cooled by a heat pump being caused to transfer thermal energy from the gas to a fluid which is circulated in an external loop (243, 244), and in that the said fluid is caused to heat indoors air or tap water in a building (210) .

2. Method according to claim 1, c h a r a c t e r i z e d i n that, in step e) , the complete remainder in the collecting vessel ( 121 ; 221 ; 321 ; 21 ) for sewage water after the evaporation of water is removed, whereby the slurry is removed to a centrally arranged plant for further treatment.

3. Method according to claim 1 or 2, ch a r a c t e r i z e d i n that the gas which during the said circulation is brought into or out from the collecting vessel (121;221;321;421) is caused to pass a filter (131, 137a, 140a;231, 237a, 245a; 331, 337a; 431, 464a) which is arranged to separate at least 99% of the bacteria possibly present in the gas.

4. Method according to any one of the preceding claims, ch a r a c te r i z e d i n that the condensed water is brought to an equalizing vessel ( 122 ; 222 ; 322 ; 422 ) for condensed water, from which condensed water is brought to the second water closet for use for flushing therein, and in that a surplus of condensed water is brought from the equalizing vessel for condensed water to an infiltration bed (102;202; 302; 402) in the ground (115; 215; 315; 415) .

5. Method according to any one of the preceding claims, ch a r a c te r i z e d i n that the said gas is circulated in a closed loop through the collecting vessel ( 121 ; 221; 321 ; 421 ) for sewage water, whereby the gas is brought from the collecting vessel, to the dehumidification step (130, 139;230, 227; 351; 60, 461) and back to the collecting vessel after separation of condensed water.

6. Method according to any one of the preceding claims, ch a r a c te r i z e d i n that the said circulating gas is caused to be heated before it is brought through the collecting vessel (321; 421) for sewage water.

7. Method according to claim 6, ch a r a c t e r i z e d i n that a heat pump (354) is arranged to transfer thermal energy from the gas passing through the dehumidification step (351) to the gas travelling past a heating location (353) arranged between the dehumidification step and the collecting vessel (321) .

8. Method according to claim 6, c h a r a c t e r i z e d i n that the gas is heated using solar energy which is absorbed via a solar collector (463) .

9. Method according to any one of the preceding claims, c h a r a c t e r i z e d i n that the gas in the dehumidifi- cation step (460,461) is cooled by thermal energy being transferred from the gas to the ground (415) or to a natural water body using a cooling loop (461) .

10. Method according to any one of the preceding claims, c h a r a c t e r i z e d i n that the building (210) in which indoors air or tap water is heated using the said fluid is a building (210) in which the first and/or second water closet (211) is installed.

11. Method according to any one of the preceding claims, c h a r a c t e r i z e d i n that the said dehumidification step (130,139) comprises a sorption dehumidification step, whereby circulating gas comprising the evaporated water vapour is brought, in a first sorption operation phase, through a moisture absorbing material body (135), whereby a gas, in a second sorption operation phase, with a higher temperature than said circulating gas had in the first sorption operation phase, is brought through the said material body, whereby the moisture content absorbed by the material body from the circulating gas in the first sorption operation phase is taken up by evaporation to the said warm gas, and whereby the water vapour taken up in the second sorption operation phase is condensed to form the said condensed water.

12. Method according to any one of the preceding claims, c h a r a c t e r i z e d i n that the first water closet (111;211; 311;411), the second water closet, the collecting vessel (121 ; 221; 321 ; 21) , the equalizing vessel (122;222; 322; 422) and the dehumidification step

(130, 139;230,227;351;460, 461) , any heating devices (353; 463) and all necessary pipes, valves and the like, are all caused to constitute fixedly installed parts of a fixedly and permanently installed installation for handling of sewage water in a property with no municipal sewage.

13. Method according to any one of the preceding claims, c h a r a c t e r i z e d i n that only sewage water form one or several water closets (111; 211; 311; 411) is brought to the collecting vessel ( 121; 221; 321; 421 ) for sewage water, and in that no sewage water originating from other types of sewage producing units is brought to the said collecting vessel.

14. Device for purifying sewage water from a first water closet (111; 211; 311; 411) , wherein the device comprises a locally arranged collecting vessel (121; 221; 321; 421) for sewage water arranged to receive sewage water from the water closet; a circulating means ( 132 ; 232 ; 332 ; 432 ) arranged to circulate a gas through the collecting vessel and thereby causing the gas to bring with it a share of the contents in the collecting vessel in the form of evaporated water vapour; and a dehumidification step (130, 139; 230, 227; 351; 460, 461) arranged to cause the said water vapour to condense and collect the thus condensed water, wherein the device is arranged to bring the condensed water to a second water closet, which may be the same as the first water closet, for use for flushing therein, and in that the device comprises emptying means ( 127 ; 227 ; 327 ; 427 ) for emptying and removing from the collecting vessel, for further treatment, the slurry which remains in the collecting vessel after the said evaporation, c h a r a c t e r i z e d i n that the dehumidification step (230,242) is arranged to cool the gas using a heat pump, arranged to transfer thermal energy from the gas to a fluid which is circulated in an external loop (243, 244), and in that the said fluid is arranged to heat indoors air or tap water in a building (210) .

15. Device according to claim 15, c h a r a c t e r i z e d i n that the device is arranged to circulate the gas in a closed circuit through the collecting vessel ( 121 ; 221; 321 ; 421 ) for sewage water, whereby the gas is brought from the collecting vessel, to the dehumidification step (130, 139;230, 227; 351; 460, 461) and back to the collecting vessel after separation of condensed water.

Description:
METHOD FOR PURIFYING SEWAGE WATER

The present invention relates to a method and a device for handling and purifying sewage water from one or several water closets.

In general, during normal use a property gives rise to sewage water, by equipment installed in the property, in the form of both gray water and black water. Gray water producing equip- ment comprises washbasins, showers, dishwashers, etc. Black water producing equipment comprises water closets . For properties with no municipal sewage, there is a problem to dispose of such sewage water in an environmentally friendly way. In a so called infiltration bed, sewage water is released, after slurry separation and filtration, into the ground. This is, however, not always possible because of current regulations, in particular for sewage water from water closets risking contamination of the ground and subsoil water with nutrient salts, bacteria and so forth. Upstream of an infiltration bed, a slurry separation step is often used, such as a conventional three-compartment septic tank. When the surrounding ground is waterlogged, such a step runs the risk of so called backflow, when water enters the step from down- stream thereof, and therein contributes to unwanted sludge flight and potential ground contamination.

Another alternative is to install a closed storage tank for sewage water. The tank is emptied regularly or when needed, whereby the sewage water is transported away from the property for suitable treatment. This if often not allowed or advisable for properties lacking municipal water, since freshwater is then normally taken from the subsoil water via a local well, without being restored in equal amounts. Thereby, subsoil unbalances arise, with risk of for instance salt water penetration and drying of wells. Moreover, frequent slurry exhaustion is necessary, to great cost. Moreover, it is often not advisable or allowed to exploit fresh water from water courses connected to the sea, such as for flushing of a water closet which is connected to an infiltration bed, since this may lead to unacceptable amounts of nutrition salts and bacteria in the local environment at the property.

It is furthermore, from the viewpoint of society, desirable to collect the nutrition- and energy carrying parts of the sewage water, such as biological material and nutrition salts, for return to the larger circulation. A conventional purification step, such as a so called mini purification installation (Swedish "minireningsverk" ) , often removes a certain share of this desirable material through for instance oxidation of carbon containing material, collection of cer- tain chemicals such as phosphorous in filters and the like, that later must be deposited, and so on. This results in that these compounds cannot be exploited optimally in the larger material cycle. The dry substance in sewage water from water closets constitutes a valuable raw material for production of for instance biogas. As such, there are however specific requirement regarding for example content of chemical contaminants and degree of dryness of the sewage slurry.

Apart from being expensive, a conventional purification step of the above described type is also many times connected directly to the sewage pipe, which results in that operation faults cause an immediate interruption of the purification function, which either leads to that sewage water producing equipment such as a water closet or a dishwasher cannot be used before the visit of a service technician, or, which is worse, that sewage water from such equipment pours straight through the faulty purification step and out into nature without the user gaining immediate information about this. Moreover, such a purification step typically consumes environmentally harmful chemicals, which must be taken care of or be released into nature.

Furthermore, many conventional sewage handling systems for use in properties with no municipal sewage raise specific demands on the type of sewage water producing equipment that can be used in properties, such as requirements for water closets with low water consumption. This does not only limit the freedom of the user, but also results in that such systems are associated with high installation costs.

The Swedish patent no. 531290 describes a method for maintaining the water balance in a property, in which sewage water is removed and freshwater, for local storing, is returned in corresponding amounts. Apart from frequent slurry exhaustion, this method requires regular external replenishing of freshwater.

Finally, for reasons of convenience, there is a need for portable toilet arrangements, comprising water closets, in places lacking municipal sewage or other permanent ways to take care of sewage water from a toilet. This is for instance the case at festivals and other temporary events, at construction sites, scenes of disaster and in developing countries . To sum up, it is desirable to achieve a method for handling sewage water from one or several water closets, which method is highly reliable and only minimally affects the local water circulation, which requires only a minimum of maintenance and slurry exhaustion, which can collect the total energy- and nutrition carrying fraction and which is inexpensive both to install and to operate.

The present invention solves the above described problems.

Hence, the invention relates to a method for purifying sewage water from a first water closet, comprising the steps a) bringing the sewage water from the first water closet to a locally arranged collecting vessel for sewage water; b) circulating a gas through the collecting vessel and thereby causing the gas to bring with it a share of the contents in the collecting vessel in the form of evaporated water vapour; c) in a dehumidification step causing the said water vapour to condense and collecting the thus condensed water; d) using the condensed water for flushing in a second water closet, which may be the same as the first water closet; and e) removing the slurry which remains in the collecting vessel after the said evaporation from the collecting vessel for further treatment.

The invention also relates to a device for purifying sewage water from a first water closet, characterised in that the device comprises a locally arranged collecting vessel for sewage water arranged to receive sewage water from the water closet; a circulating means arranged to circulate a gas through the collecting vessel and thereby causing the gas to bring with it a share of the contents in the collecting vessel in the form of evaporated water vapour; and a dehumidifi- cation step arranged to cause the said water vapour to con- dense and collect the thus condensed water, in that the device is arranged to bring the condensed water to a second water closet, which may be the same as the first water closet, for use for flushing therein, and in that the device comprises emptying means for emptying and removing from the collecting vessel, for further treatment, the slurry which remains in the collecting vessel after the said evaporation.

The invention will now be described in detail, with reference to exemplifying embodiments of the invention and to the appended drawings, where:

Figures 1-4 are explanatory sketches illustrating first, second, third and fourth exemplary embodiments of the present invention, respectively.

In all figures, the same last two digits are used for the corresponding parts in the reference numerals. The first digit relates to the number of the figure. For example, the building is denoted as 110 in figure 1 and 210 in figure 2. In the following description, sometimes unnecessary description of such already described parts is omitted, in order to avoid needless repetitions. Hence, figure 1 shows a building 110 on the ground 115, in the form of a small house or an apartment building. In the building 110 there is a toilet 111 fixedly and permanently installed. It is realized that the building 110 can have more than one toilet 111 fixedly and permanently installed, for which other water closets what is said herein is correspondingly applicable. The toilet 111 is a water closet, and therefore flushed with water. Preferably, the toilet 111 is not of a type consuming only very little water (Swedish "ultrasnalspolande", ultra low flushing) , in other words the flushing volume of the toilet 111 is preferably at least 2 liters. Specifically, it is preferred that the same toilet 111 which was previously used in the property is used as a part of an installation according to the present invention also after the installation is completed. This results for instance in that the moisture barrier in the sanitary room in which the toilet 111 is arranged does not have to be broken.

The sewage water is brought from the toilet 111, via a sewage pipe 124, to a collecting vessel 121 for sewage water which is locally arranged, i.e. arranged on the same property as, and preferably adjacent to, the space in which the toilet 111 is installed. It is preferred that sewage water to no part is brought on further from the collecting vessel 121, apart from that part of the water fraction is removed as described below .

Moreover, it is preferred that the residual fraction, in other words the slurry remaining in the collecting vessel 121, every now and then, when so is needed as the volume of sewage water becomes too large or when its level of dryness becomes too high, and/or regularly, is emptied, preferably by conventional slurry exhaustion via a connection 127, and is removed from the collecting vessel 121 for further treatment. Such further treatment is for instance constituted by anaerobic digestion to biogas, and is preferably performed at a central plant. In other words, it is preferred that the complete remainder in the collecting vessel 121, after the below described evaporation of water, is removed from the vessel 121 in this way for central treatment.

A gas, which preferably is air but which may also be an inert gas in the form of nitrogen or the like, is according to the invention circulated through the collecting vessel 121 and is thereby brought into contact with the sewage water held therein. The gas can be circulated through the sewage water itself, such as using bubbling at a certain depth in the sewage water in the vessel 121, and/or circulated past the surface of the sewage water in the atmosphere existing above this surface inside the vessel 121.

By the contact with the sewage water, the gas will take up water vapour evaporated from the contents of the collecting vessel 121, and thereby carry with it such water vapour. It is preferred that the gas is circulated with such low velocity in relation to its temperature that it becomes saturated to at least 40%, more preferably 50%, more preferably at least 90%, most preferably essentially 100%, with water va- pour, in case the dry contents of the contents in the vessel 121 are at the most 50%, more preferably at the most 25%. At such levels of dryness, it is also preferred that the gas circulating through the vessel 121 at each percolation increases the moisture contents in the gas by at least 25% relative humidity, more preferably at least 50% relative humidity .

According to the invention, the gas is then brought further to a dehumidification step, in which the water vapour con- tents of the gas at least partly are caused to condense to liquid water. The thus condensed water is thereafter collected, and is brought to an equalizing vessel 122 for condensed water. From there, the condensed water is then brought, via a conduit 125 and a pump 112, to a second water closet, which may be the same as the first water closet 111, and is used therein for flushing in the said second toilet. It is noted that in the figures the first and second water closet are both shown as the toilet 111, but it is realized that a freely selectable number of water closets for instance can share the same purification installation according to the present invention, and thereby use the same collecting vessel 121, etc. It is preferred that the vessel 122 constitutes the sole source of flushing water for the second water closet, preferably for all water closets installed in the same building 110 and preferably on the same property.

It is preferred that the equilizing vessel 122, via a connection 128, initially is supplied with a certain amount of freshwater, so that the water closet 111 can be flushed already at the start of operation.

For cost and space reasons, it is also preferred that the collecting vessel 121 and the equalizing vessel 122 constitute two separate parts of one and the same container 120, separated by an intermediary wall 123. The vessels 120, 121, 122 are preferably buried in the ground, and at least arranged above or below ground in a frost-proof way.

Since the water closet 111 by its use supplies more water than the used flushing water, in some applications a surplus of condensed water will arise over time in the equalizing vessel 122. It is preferred, in particular in the preferred case in which the sewage water in the collecting vessel 121 only originates from one or several water closets and not from other sewage water producing units such as dishwashers and washing machines, showers, etc., that such surplus water is brought, via overflow, pumping or in another other way, from the equalizing vessel 122, via a conduit 101 to an infiltration bed 102 in the ground 115. Namely, the levels of environmentally harmful chemicals and microorganisms of such condensed water have in many cases proven to be acceptably low for infiltration. Alternatively, the surplus water is used for irrigation. In figure 1, an embodiment of an installation according to the invention is shown which is arranged to be operated over two phases for dehumidifying the gas circulated through the collecting vessel 121, using sorption dehumidification . In figure 1, filled arrows illustrate the flow direction of the gas in the first phase, non filled arrows illustrate the corresponding flow direction in the second phase. Corresponding flow direction arrows are also found in figures 2-4.

Hence, the gas is caused, using a fan 132, to flow out from the vessel 121, via a filter 131.

Thereafter, the gas flows, via a pipe 133, to a sorption dehumidification step 130, comprising a moisture absorbing material body 135, which is conventional as such, and for example is a block of foam rubber. The circulating gas, comprising the evaporated water vapour from the vessel 121, is brought through a heating device 134, for instance in the form of an electrical heating element, the heating function of which is switched off during the first phase, via the material body 135 and, via a valve 136, a pipe 137 and a filter 137a, back to the collecting vessel 121. Thereby, a certain share of the moisture contained in the gas is absorbed by the material body 135, so that the gas returning to the vessel 121 is dryer after passage through the material body 135.

In the second phase, which for example is initiated after a certain time, the damp gas is brought from the vessel 121, via the pipe 133, to the heating device 134, the heating function of which is now switched on. By passing there through, the gas is thus heated to a higher temperature before again passing through the damp material body 135, there- by drying the liquid out of the material body 135, whereby the moisture content in the material body 135 which was absorbed in the first phase is taken up by the heated gas through evaporation. The gas is then brought further, via the valve 136 and a pipe 138, on to a condensing device 139, which is conventional as such, such as a conventional cooling tube, arranged to condense the absorbed water vapour. The condensing water is brought, through a pipe 141 and a filter 141, to the vessel 122 which is thus filled.

Then, the gas is in turn brought, via a pipe 140 and a filter 140a, back to the vessel 121, whereby the gas is circulated in a closed loop through the collecting vessel 121, whereby the gas is brought from the collecting vessel 121, to the dehumidification step, which in this case comprises both the step 130 and the condensing device 139, and back to the collecting vessel 121 after separation of condensed water to the equalizing vessel 122. Note that a closed loop is also present for the gas during the first phase.

After a certain time, or for instance when the material block 135 is sufficiently dry, the first phase is then resumed, according to the above, whereby the method continues in an iterative manner.

Figure 2 illustrates an alternative or supplementary embodiment in relation to the one shown in figure 1, wherein the condensing device 139 comprises or is replaced with a cooling device 242, which by heat exchange to a fluid which is circulated in an external loop 243, 244 transfers thermal energy from the gas to said fluid so that the gas thereby is cooled. Alternatively, the device 242 comprises a heat pump which is arranged to transfer thermal energy from the gas to the fluid with corresponding results. The fluid is thereafter used to heat indoors air or tap water in a building in which the first and/or the second water closet 211 is installed. This way, efficient cooling, and thereby also efficient condensing, of the gas can be achieved, at the same time as the residual heat can be exploited in the operation of the property .

The condensed water is brought, via a filter 246 and a pipe 247, back to the equalizing vessel 222. The dried gas is brought, via a pipe 245 and a filter 245a, back to the collecting vessel 221 so that the gas circuit is thereby closed.

Figures 3 and 4 illustrate further exemplary embodiments of the invention, according to which the circulated gas is caused to circulate in only one, continuous, phase, and to be heated before it is brought through the collecting vessel 321, 421.

In figure 3, a device 350, comprising both a dehumidification step and a heating step, is used, which device 350 further comprises a heat pump 354 which is arranged to transfer thermal energy from the gas passing through the dehumidification step to the gas passing past the heating step, where the heating step is arranged between the dehumidification step and the collecting vessel 121.

More precisely, the gas is brought, again using a fan 332, via a filter 331 and a pipe 333, to a first heat exchanger 351, further on via a pipe 352 to a second heat exchanger 353, and back via a pipe 337 and a filter 337a to the vessel 121. The heat pump 354 is arranged to transfer thermal energy from the heat exchanger 351 to the heat exchanger 353, whereby the gas flowing through the heat exchanger 351 is cooled at the same time as the gas which flows downstream thereof through the heat exchanger 353 is heated. In other words, the heat exchanger 354 establishes a temperature difference between the gas which has just passed the heat exchanger 351 and the gas which has just passed the heat exchanger 353.

As a result of the cooling in the heat exchanger 351, a share of the evaporated water vapour is condensed from the air, and is led via a pipe 355 and a filter 356 to the equalizing vessel 322. Thereby, the heat exchanger 351 constitutes a cooling step.

As a result of the heating in the heat exchanger 353, which thus constitutes a heating step, the gas which is brought back to the vessel 321 will be warmer than the gas after the cooling step, which increases the evaporation in the vessel 321 and also reinstitutes the capacity of the gas to carry with it evaporated water vapour back to the cooling step.

The said temperature difference can be used in various ways, by suitable choices of the properties of the heat pump 354 and the heat exchangers 351, 353, and by using any additional cooling- and heating devices which are conventional as such. For instance, the temperature of the gas can be arranged to be higher than the surrounding temperature in the space in which the vessel 321 is arranged, such as the ground temperature in case the vessel 321 is buried underground. In this case, it will thus be possible to increase the evaporation, and an equilibrium regarding the temperature profile within the vessel 321 will be reached after continuous operation for some time. This equilibrium temperature profile will comprise elevated temperatures in relation to the surrounding temperature in case the cooling achieved by the evaporation inside the vessel 321 does not compensate for the thermal energy which is added via the warm gas. According to an alternative example, the temperature of the gas returning to the vessel 321 may be essentially the same as the temperature surrounding the vessel 321, whereby no energy is used to heat the interior of the vessel 322. Alternatively, the temperature of the heated gas is lower than the surrounding temperature, whereby the surrounding material adds thermal energy, heating the evaporated liquid inside the vessel 321. In all these and other examples, the temperature difference created by the heat pump 354 can be of the same magnitude, so that the gas after the cooling step preferably is between 5 and 15°C lower than after the heating step.

An advantage with such method is that the temperature of the gas which is brought through the pipe 337 and back to the vessel 321 temporarily can be controlled up, in order to when so is needed temporarily increase the performance of the installation while accepting a higher energy cost.

Figure 4 illustrates an alternative way to achieve the cool- ing and heating of the circulated gas described in connection to figure 3.

Hence, the gas is brought, using a fan 432, through a filter 431 and a pipe 433, to a heat exchanger 460 of counter- or cross flow type. From there, the gas is brought through a cooling loop 461 which is buried in the ground 415, alternatively lowered into a natural body of water such as a water course or the sea, and back through the heat exchanger 460. Thereby, the gas arriving from the pipe 433 is cooled by the cooled gas which arrives from the cooling loop 461. The resulting condensing water is brought, through a pipe 465 and a filter 466, to the equalizing vessel 422. The cooled gas is brought on further, through a pipe 462, to a solar collecting device 463 which is arranged to heat the gas using solar energy, after which the gas is returned to the vessel 421 through a pipe 464 and a filter 464a.

This results in that no additional external energy must be supplied to the system, apart from energy to maintain the circulation of the gas.

It is preferred that the first and second water closets, the collecting vessel for sewage water, the equalizing vessel for condensed water, the above described dehumidification step in its various forms, all cooling loops, pumps, fans, pipes, valves and filter described herein, the eventual heating step, and so on, all are caused to constitute fixedly installed parts of a fixedly and permanently installed installation for handling of sewage water in a property lacking municipal sewage.

Moreover, it is preferred that only sewage water from one or several water closets are brought to the collecting vessel for sewage water, and that no sewage water originating from other types of sewage water producing units is brought to the said collecting vessel. Namely, it has turned out that sewage water from toilets after evaporation, passage through a carbon filter and condensing in general is sufficiently clean for being released into an infiltration bed in nature. Even if the sewage water is allowed both from water closets and from other sewage producing units, the condensed water is however sufficiently clean for safely being used for flushing in the toilet, even if the condensed water does not hold food grade quality.

It is preferred that the equalizing vessel for sewage water has a volume of at least 0.5 m 3 , rather 1 m 3 , in order to be able to hold sewage water from the at least one water closet. A control device 114, 214, 314, 414 is arranged to control the operation of the pumps, fans and valves described herein. It is preferred that all gas connections to and from the collectint vessel 121, 221, 321, 421 for sewage water are provided with filters 131, 137a, 140a, 231, 237a, 245a, 331, 337a, 431, 464a of a type preventing at least 99%, rather at least 99.9%, of the eventual bacteria contents of the gas to pass the filter in question. One suitable type of such filters is filters of so called HEPA (High-Efficiency Particulate Air) type. This results in that parts of the installation arranged to be external in relation to the vessel 121, 221, 321, 421 do not risk being clogged as a consequence of fouling.

Moreover, it is preferred that the condensed water used for flushing in the water closet is filtered through a filter with active coal, that is a filter through which the air is forced to flow through porous activated carbon. This removes smelly substances in the condensed water, as well as certain other pollutants, which for instance results in that the flushing water does not smell in the toilet. In order to achieve this, it is preferred that the filters 141a, 246, 356, 466 through which the condensed water is brought on its way to the equalizing vessel 122, 222, 322, 422 for condensed water is of such type with active coal. It is also possible to use such an active coal filter along the pipe 125, 225, 325, 425 between the vessels 122, 222, 322, 422 and the toi- let.

The purified water in the vessel 122 is thus used for flushing the toilet 111, and is thereafter returned to the vessel 121 for repurification, whereby a closed circuit is achieved. By using both the collecting vessel 121 for sewage water and the equalizing vessel 122 for purified water, it becomes possible for the water closet 111 to be made self-supporting regarding flushing water, despite that the flow from and to the water closet 111 is intermittent while the flow of condensed water to the vessel 122 instead is limited per time unit but on the other hand is more or less continuous.

Thus, with such a method and such a device it is achieved that a property which is not connected to municipal sewage can be provided with one or several water closets. Instead, it is sufficient that the substantially more limited amounts of slurry in the vessel 121 can be emptied when so is needed. Such emptying can take place at even intervals, alternatively when the contents reach a certain smallest volume and at the same time a desired degree of dryness. Conveniently, the volume inside the vessel 121 may be supervised using a measurement equipment 113, for instance in the form of a counter or a flow meter, which measures the number of flushes or the amount of flushed water in the toilet 111, and communicates these data to the control device 114. At the same time, the volume in the vessel 121 can be measured by a measurement device 126, such as a level sensor, placed therein, which also communicates measurement data to the control device 114. The degree of dryness can then be estimated with sufficient accuracy by comparing the amount of flushed sewage water to the current volume of sewage water in the vessel 121.

Especially, the same level of dryness can be reached regard- ing the sewage water in the vessel 121 using a toilet arranged to flush a normal or smaller amount of water (about 2- 8 liters per flush) that can be reached using so called ultra low flushing toilets (that is, with flush volumes of about 1 liter or less) . Thereby, an installation according to the present invention is an adequate alternative to installing such ultra low flushing toilets, which both leads to that the moisture barrier in the sanitary room has to be broken and to a less agreeable experience for the user.

The two equalizing vessels 121, 122 comprise, according to the embodiment illustrated in the figures, two chambers in one and the same container 120, separated by an intermediary wall 123. Such a container 120, which suitably is manufactured as an elongated cylinder of plastic material, comprises two opposite end walls and the intermediary wall 123 between them, is for instance described in the Swedish patent no. 531290, and results in a simple and inexpensive manufacturing and installation.

Above, preferred embodiments have been described. However, it is apparent to the skilled person that many modifications may be made to the described embodiments without departing from the idea of the invention.

Thus, the embodiments illustrated in each one of figures 1-4 can be combined as applicable. For instance, an electric heater according to figure 1 or a heat pump according to figure 3 can be used as support heat for an installation according to figure 4, for use when the sun does not shine. Another example is that any surplus heat from the heating of the gas using a heat exchanger 354 according to figure 3 can be led off to an external loop using a device 242 in the way described above in connection to figure 2.

Moreover, it is possible to design an installation according to the invention as a portable installation for use onboard boats, on quays and in natural harbors, at construction sites or in other places where there is a need for a water closet but where there is no municipal sewage. In this case, the surplus water may be released from the vessel 122 into for instance a street inlet, and the useful operation time of the installation before it becomes necessary to exhaust slurry from the vessel 121 becomes long.

Hence, the invention shall not be limited to the described embodiments, but may be varied within the scope of the enclosed claims.