SE536477C2 - Procedure for purifying wastewater - Google Patents

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.

Description

30 535 47? amount. Thus. imbalances occur in the groundwater balance, with the risk of, for example, salt water intrusion and drainage of water wells. In addition, frequent sludge suction is required, which is costly.

Furthermore, it is often not advisable or permissible to use fresh water from watercourses or the sea for, for example, flushing a water toilet that is connected to an infiltration plant, as this can add unacceptably large amounts of nutrients and bacteria to the local environment at the property.

Furthermore, from the society's perspective, it is often desirable to collect the business and. the energy-bearing parts of the wastewater, such as biological material and nutrients, for return to the larger cycle. A conventional treatment step, such as a so-called mini treatment plant, often removes a certain part of this desirable material by, for example, oxidation of carbonaceous material, collecting certain chemicals such as phosphorus in filters and the like which must later be deposited, and so on. .

This means that these substances cannot be utilized optimally in the larger cycle.

The dry substance in wastewater from water toilets constitutes a valuable raw material for the production of, for example, biogas. As such, however, specific requirements are placed on, among other things, the degree of chemical contamination and the degree of dryness of the sewage sludge.

In addition, a conventional treatment step of the above-mentioned type is often, extremely expensive, connected directly to the sewer line, which means that operational faults cause immediate cessation of the treatment function, which either leads to waste water-producing equipment, such as a water toilet or a dishwasher, not being used. while waiting for service technicians, 10 15 20 25 30 536 477 or, which is worse, that the wastewater from such equipment flows straight through the failed purification stage and into nature without the user receiving immediate information about this. In addition, such a purification step typically also consumes environmentally harmful chemicals, which must be disposed of or released into nature.

Many conventional sewage management systems for use in properties without municipal sewers further place specific requirements on the type of wastewater-producing equipment that can be used in buildings, such as requirements for low-flush water toilets. This not only infringes on the freedom of the user, but also means that such systems are associated with increased installation costs.

The Swedish patent with number 531290 describes a procedure for maintaining the water balance in a property, where wastewater is removed and fresh water, for local storage, is returned in a corresponding amount. This procedure requires, in addition to frequent sludge suction, regular external refilling of fresh water.

Finally, for reasons of convenience, there is a need for portable toilet facilities, including water toilets, in places that do not have a municipal sewer or other permanent way of disposing of waste water from a toilet. This applies, for example, to festivals and other temporary events, to construction sites, disaster sites and in 'developing countries'.

In summary, it is desirable to provide a method for managing wastewater from one or more water toilets that only minimally affects the local water cycle and. is reliable, which requires a minimum of maintenance and sludge suction, which can collect the entire energy and nutrient-containing fraction and sonx is cheap both to install and to operate.

The present invention solves the problems described above.

Thus, the invention relates to a method of purifying wastewater from a first water toilet, comprising the steps of: a) transferring the waste water from the first toilet to a locally arranged waste water collection container; b) circulating a gas through the collection container and thereby causing the gas to carry part of the contents of the collection container in the form of evaporated water vapor; c) in a dehumidifying step causing said water vapor to condense and collect the water thus condensed; d) use the condensed water for flushing in a second water toilet, which may be the same as the first water toilet; and e) removing the sludge. son1 after said evaporation remains in the collection container from the collection container for further treatment, which method is characterized in that said gas is circulated in a closed cycle through the collection container for wastewater, whereby the gas is carried from the collection container, to the dehumidification step and back to the collection container. of condensed water, that all of the first water toilet, the second water toilet, the collection tank and the dehumidification step are made to form permanently installed parts of a fixed and permanently installed system for handling wastewater in a property that does not have a municipal sewer, the dehumidification step is caused to be cooled by causing a heat pump to transfer heat energy from the gas to a fluid circulating in an external loop, and by causing said fluid to heat indoor air or domestic hot water in a housing in which 47? the first and / or the second water toilet is installed.

The invention also relates to a device for purifying wastewater from a first water toilet, the device comprising a locally arranged one. waste water collection containers arranged to receive waste water from the water toilet; a circulating means arranged to circulate a gas through the collecting container and thereby cause the gas to carry a part of the contents of the collecting container in the form of evaporated water vapor; and a dehumidifying step, arranged to cause said water vapor to condense and collect the water thus condensed, in that the device is arranged to carry the condensed water to a second water toilet, which may be the same as the first water toilet, for use in flushing therein, and in that the device comprises emptying means for emptying and removal for further treatment of the sludge remaining after said evaporation in the collection container from the collection container, which device is characterized in that the circulation device is arranged to circulate the gas in a closed cycle through the collection container for wastewater. wherein the gas is carried from the collection container, to the dehumidification stage and back to the collection container after separation of condensed water, in that all of the first water toilet, the second water toilet, the collection container and the dehumidification step form permanently installed parts of a fixed and permanent insert. a plant for managing wastewater in a property which does not have a municipal sewer, in that the dehumidification step is arranged to cool the gas by means of a heat pump which is arranged to transfer heat energy from the gas to a fluid circulating in an external loop, and in that said fluid is arranged to heat indoor air or domestic hot water in a house in which 10 15 25 30 535 47? the first and / or the second water toilet is pre-installed.

The invention will now be described in detail, with reference to exemplary embodiments of the invention and the accompanying drawings, in which: Figures 1-4 are schematic diagrams illustrating first, second, third and fourth devices, respectively, for purifying water from a respective toilet. Figure 2 is an exemplary embodiment of the present invention.

In all figures, the same last two digits in the reference numerals are used for the corresponding parts. The first number is attributable to the figure number. For example, the housing is indicated as 110 in Figures 1 and 210 in Figure 2. In the following description, description of such already described parts is sometimes omitted, in order to avoid unnecessary repetitions.

Figure 1 thus shows a house 110 on the ground 115, in the form of a detached house or an apartment building. In the house 110 there is a toilet 111 permanently and permanently installed. It will be appreciated that the housing 110 may have more than one toilet 111 permanently and permanently installed, to which other toilets what is stated herein is correspondingly applicable. toilet, Toilet 111 is a water which is flushed with water. Preferably, the toilet 111 is not of the so-called ultra-low-flush type, i.e. the flush volume of the toilet is preferably at least 2 liters. In particular, it is preferred that the same toilet 111 as previously used in the property also continues to be used as part of a plant according to the present invention after the plant in question has been installed. This means, for example, that the sealing layer in the wet room in which the toilet 111 is located does not have to be broken. 10 15 25 30 535 47? The wastewater is led 124, from the toilet 111, via a drain pipe to a local, ie. on the same property as, and preferably in the immediate vicinity of, the room in which the toilet 111 is installed, arranged a collection container 121 for wastewater. It is preferred that the wastewater is not passed on from the collection container 121 to any extent, except that the water fraction is partially removed, as described below.

In addition, it is preferred that the remaining fraction, in other words the sludge remaining in the collection container 121, be emptied from time to time, when necessary when the volume of waste water becomes too high or its dry content becomes too high, and / or at regular intervals. preferably by conventional sludge suction via a connection 127, and. removed from the collection container 121 for further processing. Such further treatment consists, for example, of digestion into biogas, and is preferably carried out at a central plant. Thus, it is preferred that the entire residue in the collection container 121, after the evaporation of water described below, be removed from the container 121 in this way for central handling.

A gas, which is preferably air but which can also be an inert gas in the form of nitrogen or the like, is circulated according to the invention through the collecting container 121 and comes into contact therewith with the waste water housed therein. The gas can be circulated through the wastewater itself, such as by bubbling at a certain depth into the wastewater in the container 121, and / or circulated past the surface of the wastewater in the atmosphere present above this surface in the container 121.

Through contact with. the wastewater, the gas will absorb water vapor that has evaporated from the contents of the collection container 121, and thus carry such water vapor with it. It is preferred that the gas be circulated at such a low speed in advance. maintaining to its temperature that it becomes saturated to at least 40%, more preferably 50%, more preferably at least 90%, preferably substantially 100%, with water vapor, in case the dry matter content of the contents of the container 121 is at most 50%, preferably not more than 25%. At such dry contents it is also preferred that the gas circulated through the container 121 at each flow-through increases the moisture content of the gas by at least 25% relative humidity, more preferably at least 50% relative humidity.

The gas is then passed, according to the invention, to a dehumidification step, where the gas vapor content of the gas is at least partially caused to condense to liquid water. The water thus condensed is then collected and passed to a condensing vessel 122 for condensed water. From there, the condensed water is then conveyed, via a line 125 and a pump 112, to a second water toilet, which may be the same as the first water toilet 111, and is used there for flushing in said second toilet. It is noted that in the figures the first and the second water toilet are both shown as the toilet 111, but it is understood that any number of water toilets can share the same treatment plant according to the present invention, and thus use the same collection container 121 etc. It is it is preferred that the container 122 be the sole source of flushing water for the second water toilet, preferably for all water toilets present installed in the same housing 110 and preferably on the same property.

It is preferred that the equalization container 122, via a connection 128, is initially supplied with a certain amount of fresh water, so that the water toilet 111 can be flushed already at the time of commissioning.

It is also preferred for cost and space reasons that the collection container 121 and the leveling container 122 constitute two 10 15 25 30 535 47? separate parts of one and the same container 120, The containers 120, 121, buried in the ground and at least frost-free arranged above separated by a partition wall 123. 122 is preferably or underground.

Since the water toilet 111 through its use supplies more water than the flushing water used, some. applications over time an excess of condensed water to arise in the equalization tank 122. It is preferred, especially in the preferred case when the waste water in the collection tank 121 originates only from one or more water toilets and not from the others. waste water producing units such as dishwashers and washers, showers, etc., that such excess water is carried, by spreading, pumping or otherwise, from the equalization tank 122, via a line 101 to an infiltration bed 102 in the ground 115. The levels of environmentally harmful chemicals and microorganisms in such condensed water have in fact been shown to be acceptably low for infiltration in many cases. Alternatively, the excess water is used for irrigation.

Figure 1 illustrates in fact a design of a plant soul is arranged. to be operated in two phases to dehumidify the gas circulating through the collection container 121 by means of sorption dehumidification. Filled arrows illustrate in Figure 1 the flow direction of the gas in the first phase, unfilled arrows illustrate the corresponding flow direction in the second phase. Corresponding flow direction arrows are also found in Figures 2-4.

The gas is thus caused, by means of a fan 132, to flow out of the container 121, via a filter 131. 15 20 25 30 538 47? Thereafter, the gas flows, via a pipe 133, to a sorption dehumidification stage 130, comprising a per se conventional, moisture-absorbing body of material 135, such as a foam rubber block.

The circulating gas, comprising the evaporated water vapor from the container 121, is passed through a heating device 134, for example in the form of an electric heating element, the heating function of which is switched off during the first phase, through the material body 135 and, a filter 137a, via a valve 136. a tube 137 and back to the collection container 121.

As a result, a certain proportion of the moisture contained in the gas is absorbed by the body of material 135, so that the gas returning to the container 121 is drier after passage through the body of material 135.

In the second phase, which is initiated after a certain time, for example, the moist gas is conveyed from the container 121, via the pipe 133, to the heating device 134, the heating function of which is now switched on. By passing through it, the gas is thus heated to a higher temperature before it again passes through the moist material body 135, and thereby dries out the liquid from the material body 135, whereby the moisture content in the material body 135 absorbed in the first phase is taken up by the heated gas by evaporation. . The gas is then passed, via the valve 136 and a pipe 138, to a per se conventional condensing device 139, arranged as a per se conventional cooling pipe, to condense the absorbed water vapor. The condensed water is passed, through a pipe 141 and a filter 141a to the container 122 which is thereby filled. via a tube 140 and a filter back to the container 121, The gas is in turn then, 140a, whereby the gas is circulated in a closed circuit through the collecting container 121, whereby. the gas is passed from the collection container 121, to the dehumidification step, which in this case includes both the step 130 10 15 25 30 535 47? 11 and the condenser 139, and eats to the collection container 121 after separating condensed water to the equalization container 122.

Note that a closed cycle also exists for the gas during the first phase.

After a certain time, or when, for example, the block of material 135 is sufficiently dry, the first phase is started again as above, the process continuing in an iterative manner.

Figure 2 illustrates an alternative or complementary embodiment to that shown in Figure 1, wherein the condenser 139 includes or is replaced by a cooling device 242 which, by heat exchange to a fluid circulating in an external loop 243, 244, transfers heat energy from the gas to said fluid so that the gas is thereby cooled. Alternatively, the device 242 comprises a heat pump which is arranged to transfer heat energy from the gas to the fluid with corresponding results. The fluid is then used to heat indoor air or domestic hot water in a house in which the first and / or the second water toilet 211 is located. In this way an efficient cooling of the gas can be achieved, and thus also efficient condensation, at the same time as the residual heat comes for the benefit of property management.

The condensed water is returned, 247, via a filter 246 and a pipe to the equalization tank 222. The dried gas is led, via a pipe 245 and a filter 245a, back to the collection tank 221 so that the gas cycle is thereby closed.

Figures 3 and 4 illustrate further devices according to which the circulating gas is circulated in only one, continuous phase, and. to be heated 421. before being passed through the collection container 321, 10 15 25 30 538 47? In Figure 3, a device 350 is used comprising both a dehumidification stage and a heating stage, further comprising a heat pump 354 arranged to transfer heat energy from the gas passing through the dehumidification stage to the gas passing past the heating stage, the heating stage being arranged between the dehumidification stage and the dehumidification stage 321.

More specifically, the gas, 332, is again conveyed by means of a fan via a filter 331 and a pipe 333, to a first heat exchanger 351, lare 353, further via a pipe 352 to a second heat exchanger and again via a pipe 337 and a filter 337a to the container 321.

The heat pump 354 is arranged to transfer heat energy from the heat exchanger 351 to the heat exchanger 353, the gas flowing through the heat exchanger 351 being cooled at the same time as the gas flowing downstream thereof through the heat exchanger 353 is heated. In other words, the heat pump 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.

Through the cooling in the heat exchanger 351, a part of the evaporated water vapor is condensed out of the air and led via a pipe 355 and a filter 356 to the equalization container 322. Thus, the heat exchanger 351 constitutes a cooling step.

Through the heating in the heat exchanger 353, sonx thus constitutes back to the container 321 to be hotter than the gas after cooling step- a heating step, the gas which is given goat, which increases the evaporation in the container 321 and also restores the gas capacity to evaporate water vapor back to the cooling step.

The said temperature difference can be used in different ways, by suitable choices of the properties of the heat pump 354 and the heat exchangers 351, 353 and by using any external radiators. 13 liger, in themselves conventional, cooling and heating devices. For example, the temperature of the gas may be arranged to be higher than the ambient temperature in the space in which the container 321 is located, such as the ground temperature if the container 321 is buried. In this case, it will thus be possible to increase evaporation, and an equilibrium with respect to the temperature profile inside the container 321 will be achieved after a period of continuous operation. This equilibrium temperature profile will include elevated temperatures relative to the ambient temperature if the cooling caused by the evaporation in the container 321 does not compensate for the heat energy supplied by the hot gas. According to an alternative example, the temperature of the gas returning to the container 321 may be substantially the same as the ambient temperature of the container 321, with no energy being used to heat the interior of the container 322. Alternatively, the temperature of the heated gas is lower than the ambient temperature, with the environment contributing heat energy to heat the evaporating liquid in the container 321. In all these, and in other examples, the temperature difference created by the heat pump 354 may be of the same order of magnitude. , so that the gas after the cooling step is preferably between 5 and 15 ° C lower than after the heating step.

An advantage of such a method is that the temperature of the gas passed through the pipe 337 back to the container 321 can be temporarily regulated up, in order to temporarily increase the performance of the plant to a higher energy cost if necessary.

Figure 4 illustrates an alternative way of achieving the cooling and heating of the circulating gas described in connection with Figure 3. 20 25 30 538 47? The gas is thus conveyed, by means of a fan 432, filter 431 and a pipe 433, through one to a heat exchanger 460 of the counter-current or cross-current type. From there, the gas is passed through a cooling coil 461 buried in the ground 415, alternatively immersed in a natural body of water such as a stream or sea, and back through the heat exchanger 460. Thus, the gas coming from the tube 433 is cooled by the cooled gas that came more from the cooling coil 461. The resulting condensed water is passed, through a pipe 465 and a filter 466, to the equalization vessel 422. The cooled gas is further passed, through a pipe 462, to a solar collector device 463 which is arranged to heat by means of solar energy. the gas, which is then returned to the container 421 through a pipe 464 and a filter 464a.

This means that no additional energy must be supplied to the system from an external hob, except for energy to maintain the circulation of the gas.

It is preferred that the first and second water toilets, the waste water collection tank, the condensed water equalization tank, the dehumidification stage described above in its various forms, all the cooling coils, pumps, fans, pipes, valves and filters described herein, the possible heating stage, and so on , all are made to form permanently installed parts of a fixed and permanently installed facility for handling wastewater in a property that does not have a municipal sewer.

It is further preferred that only waste water from one or more water toilets is fed to the waste water collection container, and that no waste water originating from other types of waste producing units is fed to said collection container. Namely, it has been shown that wastewater from toilets after evaporation, passage through 10 15 20 25 30 535 47? Carbon filter and condensation are generally clean enough to be discharged into an infiltration bed in nature. However, even if sewage is allowed from both water closets and other sewage producing units, the condensed water is clean enough to be safely used for flushing the toilet, even if the condensed water does not maintain food quality.

It is preferred that the equalization tank for wastewater has a volume of at least 0.5 nf, preferably 1 m3, in order to be able to house the wastewater from the at least one water toilet.

A control device 114, 214, 314, the operation of the pumps, 414 described herein, is arranged to control the fans and valves.

It is preferred that all gas connections to and from 221, 321, 421 for wastewater be 137a, 14oa, 231, 237a, 24551, 331, more preferably the collection container 121, provided with filters 131, 337a, 431, 464a of a type which prevents at least 99 %, at least 99.9%, of the possible bacterial content of the gas to pass the filter in question. A suitable type of such filters are filters of the so-called HEPA type (High-Efficiency Particulate Air filters). This means that parts of the plant which are arranged externally in relation to the container 121, 221, 321, 421 do not risk being clogged due to growth.

It is further preferred that the condensed water used for flushing in the water toilet is filtered through a filter with activated carbon, i.e. a filter through which air is forced to flow through porous activated carbon. This removes foul-smelling constituents of the condensed water, as well as certain other contaminants, which, for example, means that the flushing water does not smell bad in the toilet. To achieve this 10 20 25 30 538 47? 16, it is preferred that the filters 141a, 246, 356, which the condensed water is passed on its way to the equalizer 222, 322, 466 through the condensed water 122, 422, be of the activated carbon type. It is also possible to use such an activated carbon filter along the pipe 125, 225, 325, 425 between the container 122, 222, 322, 422 and the toilet.

The purified water in the container 122 is thus used to flush in the toilet 111, and is thus returned to the container 121 for purification, whereby a cycle is achieved. By using both the waste water collection tank 121 and the purified water equalization tank 122, it is possible for the water toilet 111 to be made self-sufficient in flushing water, even though the flow from and to the water toilet 111 is intermittent while the flow of condensed water to the container 122 is rather limited per unit time. the page more or less continuously.

Thus, it is achieved by such a procedure and such a device that a property which is not connected to a municipal sewer can be arranged with one or more water toilets.

Instead, it is sufficient that the much more limited amounts of sludge in the container 121 are emptied when needed. Such emptying can take place at regular intervals, alternatively when the contents reach a certain minimum volume and at the same time a desired degree of dryness. The volume of the container 121 can conveniently be monitored by means of a measuring equipment 113, for example 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 this data to the control device 114. At the same time the volume in the container 121 is measured by one placed therein. measuring device 126, such as a level sensor, which also communicates measuring data to the control device 114. The degree of dryness can then be estimated sufficiently accurately by comparing the amount of flushed wastewater with the current volume of wastewater in the container 121.

In particular, the same degree of dryness can be achieved with respect to the wastewater in the container 121 using normal or low-flush toilets (about 2-8 liters per flush) which can be achieved with so-called ultra-low-flush toilets (ie flush amounts of about 1 liter or less) . Thus, a plant according to the present invention is a perfect alternative to installing such ultra-low-flushing toilets, which leads both to the sealing layer in the wet space having to be broken and to a less pleasant experience for the user.

The two containers 121, 122 constitute, according to the embodiment illustrated in the figures, two chambers separated by means of a partition 123 in one and the same container 120. container 120, one which is suitably made as an elongate cylinder of plastic material comprising two opposite end paths gars and the partition 123 in between, is described, for example, in the Swedish patent with number 531290, and entails simple and cheap manufacture and installation.

Preferred embodiments have been described above. However, it will be apparent to those skilled in the art that many changes may be made to the described embodiments without departing from the spirit of the invention.

Thus, the embodiments illustrated in each of Figures 1-4 may be combined as appropriate. For example, an electric heater according to Figure 1 or a heat pump according to Figure 3 can be used as a support heat at a plant according to Figure 4, for use when the sun is not shining. Another example is that any excess heat from the heating of the gas by 10 15 535 47? 18 by means of a heat exchanger 354 according to Figure 3 can be diverted to an external loop by means of a device 242 in the manner described above in connection with Figure 2.

In addition, it is possible to design a plant according to the invention as a portable installation for use on boats, quays and natural harbors, on construction sites or other places where there is a need for a water-resistant case, the excess water can be discharged from the container 122 in e.g. but there is no municipal sewer. In this a day well, and the service life of the plant before it is necessary to sludge suction container 121 becomes long.

Thus, the invention should not be limited to the embodiments described, but may be varied within the scope of the appended claims.

Claims (13)

535 47? 19 P A T E N T K R A V A method of purifying wastewater from a first water toilet (III; 211; 311; 4111), comprising the steps of: a) transferring the wastewater from the first toilet to a locally arranged waste container (112; 221; 321; 421) for wastewater; b) circulating a gas through the collection container and thereby causing the gas to carry part of the contents of the collection container in the form of evaporated water vapor; c) in a dehumidification step (130, 139; 230,242; 35l; 460,46l) causing said water vapor to condense and collect the water thus condensed; d) use the condensed water for flushing in a second water toilet, which may be the same as the first water toilet; and e) removing the sludge remaining after said evaporation in the collection container from the collection container for further treatment, characterized in that said gas is circulated in a closed cycle through the waste water collection container, the gas being passed from the collection container to the dehumidification vessel after the separation of condensed water, by bringing all of the first water toilet, the second water toilet, the collection container and the dehumidification step to form permanently installed parts of a fixed and permanently installed waste water treatment plant in a property without municipal sewage, of that the gas in the dehumidification step (230,242) is caused to be cooled by causing a heat pump to transfer heat energy from the gas to a fluid circulating in an external loop (243,244), and by causing said fluid to heat indoor air or electricity. 35 535 477 20 smiling hot water in a hu s (210) in which the first and / or the second water toilet is located. k ä n n e t e c k n a t (l2l; 22l; 32l; 421) A method according to claim 1, wherein the entire residue in the collection container for the waste water after the evaporation of water is removed in step e), the sludge being removed to a central plant for further treatment. . 3. A method according to claim 1 or 2, characterized in that the gas introduced into or (121; 22l; 32l; 42l) in said circulation is brought (131, 13a, 14a; 231, 237a, 245a; 331, 337a; 431, out of the collection container passing a filter 464a) which is arranged to separate at least 99% of the bacteria possibly contained in the gas. 4. A method according to any one of the preceding claims, characterized in that the condensed water is caused to (222; 222; 322; 422) condensed water from which condensed water is passed to it is transferred to a leveling container for the second water toilet for use. by rinsing therein, and by transferring an excess of condensed water from the condensed water equalization vessel to an infiltration bed (102; 202; 302; 402) in the ground (115; 215; 315; 415). 5. Procedure according to any. of the preceding claims, characterized in that said circulating gas is caused to be heated before it is passed through the collection container (32l; 421) for wastewater. 6. A method according to claim 5, (354) characterized in that a heat pump is arranged to transfer heat energy (351) to (353) from the gas son1 passing through the dehumidification step the gas passing past a heating point. 21 arranged between (321). the dehumidification step and the collection container 7. A method according to claim 5, characterized in that the gas is caused to be heated by means of solar energy which is absorbed via a solar collector (463). Method according to one of the preceding claims, characterized in that the gas in the dehumidification step (460,46l) is caused to be cooled by transferring heat energy from the gas to the ground (415) or to a natural body of water by means of a cooling coil (461). . A method according to any one of the preceding claims, if the water e - (210) or hot water is brought to heat (210) the second water toilet (211) is installed. t e c k n a t a v that the housing in which indoor air up by means of said fluid is a housing in which the first and / or A method according to any one of the preceding claims, characterized in that said dehumidification step (130, 139) comprises a sorption dehumidification step, wherein circulating gas comprising the evaporated water vapor in a first sorption operating phase is caused to pass (135), through a moisture absorbing material body wherein a gas in a second sorption operating phase with a higher temperature than said circulating gas had in the first sorption operating phase been passed through said material body, wherein moisture content absorbed by the material body from the circulating gas in the first sorption operating phase evaporation is taken up to said hot gas, and the water vapor taken up in the second sorption operating phase is caused to condense to form said condensed water. 15 20 25 30 535 477 22 11. ll. Procedure according to any. of the preceding claims, characterized in that only waste water from one or (lll; 2ll; 31l; 411) (l2l; 22l; 32l; 42l) several water toilets is fed to the waste water collection container, and that no waste water originating from others types of sewage-producing units are fed to the said collection container. Device for purifying wastewater from a first water toilet (III; 2111; 311; 411), locally where the device comprises an arranged collection container (112; 221; 321; 421) for wastewater arranged to receive wastewater from the water toilet ; a circulating means (132; 232; 332; 432) arranged to circulate a gas through the collecting container and thereby causing the gas to carry a part of the contents of the collecting container in the form of evaporated water vapor; step (l30, l39; 230,242; 35l; 460,46l), said water vapor to condense and. thus collecting and a dehumidifying means for bringing the condensed water, from the fact that the device is arranged to carry the condensed water to a second water toilet, which may be the same as the first water toilet, for use in flushing therein, and from the fact that the device comprises emptying means. (l27; 227; 327; 427) for emptying and removal for further treatment of the sludge remaining after said evaporation in the collection container from the collection container, characterized in that the circulation device is arranged to circulate the gas in a closed cycle by collecting from the waste water treatment tank, the gas being carried to the collection tank, to the dehumidification stage and back to the collection tank after separation of condensed water, in that all of the first water toilet, the second water toilet, the collection tank and the dehumidification stage form fixed and permanently installed parts - installed facility for hand wastewater in a property that does not have a municipal sewer, in that the dehumidification stage (230,242) is arranged to cool the gas with. by means of a heat pump arranged to transfer heat energy from the gas (243,244), and by said fluid being arranged to heat indoor air (210) in to a fluid circulating in an external loop or domestic hot water, in a housing which the first and / or the other water toilet is installed. Device according to claim 12, characterized in that the device is arranged to circulate the gas in a closed (121; 22l; 32l; 42l) cycle through, the waste water collection container, the gas being passed from the collection container, to the dehumidification step (130, 139; 230, 242). ; 35l; 460,46l) and back to the collection container after separation of condensed water.