Removing disinfection byproducts from swimming pool water

Abstract

There is provided a swimming pool system comprising a swimming pool, a recirculating system coupled to the swimming pool for recirculating pool water, a degassing system connected to the recirculating system; the degassing system comprising pressure control means for providing a pressure lower than atmospheric pressure to the pool water such that disinfectant byproducts dissolved in the pool water enters gaseous form, the degassing system further comprising means for separating the disinfectant byproducts in gaseous form from the pool water.

Description

[0001] Removing disinfection byproducts from swimming pool water

[0002] Field of the invention

[0003] This invention relates to systems and methods for the degassing of swimming pool water, in particular for the removal of disinfectant byproducts such as chloramines and trihalome-thane from swimming pool water.

[0004] Background

[0005] Everyone knows the characteristic and unpleasant smell of swimming pool water: a distinct smell of chlorine. What actually smells, however, is trichloramines that is released from the water in gaseous form. The smelly trichloramines are produced by the reaction of the chlorine added to the water with various nitrous compounds released from the human body, such as sweat and urine.

[0006] Trichloramines are not only smelly but also cause allergic reactions. Other undesirable disinfectant byproducts in pool water include trihalomethanes (THM), in particular trichloromethane. In some pools bromine is used instead of chlorine and this also causes the generation of disinfection byproducts. In general, the disinfection using chlorine, bromine or other chemicals causes the creation of disinfection biproducts.

[0007] Currently smelly dichloramines are typically removed from the swimming pool area by ventilation of the air above the swimming pool, in the case of indoor swimming pools. However, this is very energy consuming, in particular in cool climates.

[0008] Furthermore, it is difficult to monitor the amount of disinfectant byproducts in and around swimming pools. EP3899516 describes how trichloramine concentration can be measured in the air close to swimming pools. W02020 / 201562 also describes how trichloramineconcentration can be measured in the air in the space above the swimming pool. However, measuring is very expensive and it is difficult to obtain a correct measurement and this manner, which frequently leads to excess ventilation.

[0009] This invention solves these and other problems.

[0010] Summary of invention

[0011] In a first aspect of the invention there is provided a swimming pool system comprising a swimming pool,

[0012] a recirculating system coupled to the swimming pool for recirculating pool water, a degassing system connected to the recirculating system; the degassing system comprising pressure control means for providing a pressure lower than atmospheric pressure to the pool water such that disinfectant byproducts dissolved in the pool water enters gaseous form, the degassing system further comprising

[0013] means for separating the disinfectant byproducts in gaseous form from the pool water.

[0014] This provides for a simple and low cost means for removing disinfectant byproducts from pool water.

[0015] In various embodiments, the pressure provided to the pool water is lower than 0.6 ATM.

[0016] In various embodiments the degassing system comprises a gas sensor arranged to detect disinfectant byproducts in gaseous form, such as chlorinated compounds in gaseous form, that have been separated from the pool water.

[0017] This provides a convenient way to monitor the amount of chlorine in the pool water, for example to ensure that the pool water is sufficiently degassed.In various embodiments, the recirculation system comprises a particle filter and a water adjustment module and the degassing system is connected to the recirculating system downstream of the particle filter particles and upstream of a water adjustment module.

[0018] This has the advantage of not subjecting the degassing system to particles and also adjusting the water quality after the degassing step, to ensure the correct water quality.

[0019] In various embodiments, the pressure control means of comprises an ejector having a low-pressure inlet, the pressure control means further comprising a pump which provides flow of a liquid through the ejector.

[0020] An ejector has the advantage of being low cost and being reliable.

[0021] In various embodiments the degassing system is configured to use the means for separating the disinfectant byproducts in gaseous form from the pool water to separate the disinfectant byproducts in gaseous form from the pool water, and to provide the gas to the low pressure inlet of ejector such that the gas forms bubbles in the liquid being ejected, and then providing the liquid with the bubbles to means for separating gas bubbles from the liquid, to separate the gas from the liquid.

[0022] In various embodiments, the means for separating the disinfectant byproducts in gaseous form from the pool water comprises a membrane that is permeable to gases and non-per-meable to water in liquid form, the membrane being arranged with a first side in contact with the pool water, and where the pressure on a second side of the membrane is such that disinfectant byproducts dissolved in the pool water crosses the membrane as gas, and a conduit for removing the gas from the second side of the membrane.

[0023] membrane provides a very efficient degassing.

[0024] In various embodiments, the low-pressure inlet of the ejector is connected to the conduit for removing gas from the second side of the membrane, such that disinfectant byproductsin gaseous form is provided to the ejector and mixed with the liquid such that the disinfectant byproducts in gaseous form forms bubbles in the liquid, and where the outlet of the ejector is connected to means for separating the gas bubbles from the liquid.

[0025] In various embodiments, the degassing system comprises a first line comprising the pump where the pump draws pool waterfrom the recirculating system and provides it to the ejector, and where the low-pressure inlet of the ejector is connected to a second line of the degassing system, said second line arranged to draw pool water from the recirculation system, and where the pressure is maintained in the second line such that disinfectant byproducts dissolved in the pool water forms bubbles in the second line and is provided to the ejector where it is mixed with pool water from the first line, and where the outlet of the ejector is connected to the means for separating the gas bubbles from the liquid.

[0026] In various embodiments, the second line may comprise a vacuum chamber. In various embodiments, the second line comprises a pressure reduction valve.

[0027] In a second aspect of the invention there is provided a degassing system being connectable to a swimming pool recirculating system, the degassing system comprising an ejector having a low pressure inlet, and a pump which provides flow of liquid through the ejector, the low pressure inlet of the ejector being connected to the recirculating system such that disinfectant byproducts dissolved in the pool water forms bubbles in a liquid in the degassing system, the degassing system further comprising means for separating the gas bubbles from the liquid being arranged downstream of the ejector.

[0028] In some embodiments pressure control means comprises an ejector having a low-pressure inlet, the pressure control means further comprising a pump which provides flow of a liquid through the ejector, the ejector further comprising a high-pressure inlet and an outlet with a nozzle arranged to provide suction at the low-pressure inlet.In various embodiments, the degassing system comprises a membrane unit comprising a membrane that is permeable to gases and non-permeable to water in liquid form, the membrane having a first side and a second side, the membrane being arranged with the first side in contact with the pool water, and where the second side of the membrane is connected to the low pressure inlet of the ejector with a conduit such that the pressure on the second side of the membrane is such that disinfectant byproducts dissolved in the pool water crosses the membrane as gas, where the conduit is arranged to lead the gas to the low pressure inlet of the ejector such that the gas forms bubbles in the liquid being ejected by the ejector, the degassing system further being arranged to provide the liquid with the bubbles to the means for separating the gas bubbles from the liquid.

[0029] In various embodiments, a first line comprising the pump where the pump draws pool water from the recirculating system and provides it to a high-pressure inlet of the ejector, and where the low-pressure inlet of the ejector is connected to a second line of the degassing system, said second line arranged to draw pool water from the recirculation system, and where the pressure is maintained in the second line such that disinfectant byproducts dissolved in the pool water forms bubbles in the second line and is provided to the low pressure inlet of the ejector where it is mixed with pool water from the first line, and where the outlet of the ejector is connected to the means for separating the gas bubbles from the liquid.

[0030] There is also provided a degassing system connectable to a swimming pool recirculating system the degassing system comprising a comprising

[0031] pressure control means for providing a pressure lower than atmospheric pressure to the pool water such that disinfectant byproducts dissolved in the pool water enters gaseous form, the degassing system further comprising

[0032] means for separating the disinfectant byproducts in gaseous form from the pool water.

[0033] In various embodiments, the pressure control means comprises an ejector having a low-pressure inlet, the pressure control means further comprising a pump which provides flow of a liquid through the ejector. In some embodiments pressure control means comprises anejector having a low-pressure inlet, the pressure control means further comprising a pump which provides flow of a liquid through the ejector, the ejector further comprising a high-pressure inlet and an outlet with a nozzle arranged to provide suction at the low-pressure inlet.

[0034] In various embodiments, the means for separating the disinfectant byproducts in gaseous form from the pool water comprises a membrane that is permeable to gases and non-per-meable to water in liquid form, the membrane being arranged with a first side in contact with the pool water, and where the pressure on a second side of the membrane is such that disinfectant byproducts dissolved in the pool water crosses the membrane as gas, and a conduit for removing the gas from the second side of the membrane

[0035] In a third aspect of the invention there is provided a vehicle comprising a degassing system according to the second aspect of the invention, where the degassing system is reversibly connectable to a swimming pool recirculation system.

[0036] The vehicle has the advantage of providing an ambulatory degassing service to swimming pools.

[0037] In a fourth aspect of the invention there is provided a method for removing disinfectant byproducts dissolved in swimming pool water the method comprising

[0038] providing pool water to a degassing system, the degassing system at least comprising an inlet providing pool water to the degassing system and outlet providing pool water from the degassing system,

[0039] providing a pressure lower than atmospheric pressure to the swimming pool water in the degassing system such that disinfectant byproducts dissolved in the pool water enters gaseous form,

[0040] separating the disinfectant byproducts in gaseous form from the pool water.Brief

[0041]

[0042] Fig. 1 shows a swimming pool connected to a degassing system.

[0043] Fig. 2. shows a degassing system.

[0044] Fig. 3 shows a degassing system.

[0045] Fig. 4 shows a degassing system.

[0046] Fig. 5 shows a flow chart.

[0047] Detailed

[0048] In swimming pools where chlorine is used, chlorine reacts with nitrogen-containing compounds such as sweat or urine to produce mono- and dichloramine. Monochloramine and dichloramine typically do not smell but are dissolved in the water. However, these may be further chlorinated to produce trichloramine, which are smelly compounds. Trichloramine is not easily solved in the pool water but leaves the water as gas rapidly at atmospheric pressure.

[0049] The inventors have found that the amount of trichloramines, THM and other disinfectants byproducts that are released from the pool water into the air can be decreased by removing disinfectant byproducts such as mono- and dichloramines from the pool water.

[0050] Looking at Fig. 1 and 2, a swimming pool system 100 comprises a swimming pool 1 connected to a recirculating system 2 as is known in the art (apart from degassing system 3). The swimming pool 1 may be a pool which is chlorinated, for example by adding hypochlorite to the pool water. However, other chemicals such as bromine may also be used. The recirculating system 2 may comprise a variety of components for maintaining the quality of the pool water and the comfort and safety of the users of the swimming pool, such as a particle filter 30 for removing particles, as is known in the art. The recirculating system 2 may, as is known in the art, comprises a water adjustment module 31 for measuring and adjusting various properties of the pool water such as for example measuring and adjustingthe pH or the conductivity of the pool water or for adding a source of chlorine or other disinfectants to the pool water, such as for example hypochlorite.

[0051] The recirculation system 2 may comprise temperature control means such as heater 32 or cooler, for controlling the temperature of the swimming pool water. The swimming pool water preferably has a temperature between 24°C to 32° C, preferably from 25° C to 31° C and most preferably from 26° C to 30° C.

[0052] The pool water is drawn from the swimming pool 1 and circulates in the recirculation system 2 with the use of pool pump 33.

[0053] The swimming pool system 100 further comprises a degassing system 3. The degassing system 3 is connected to the recirculation system 2 and may form a part of recirculation system 2. The degassing system 3 is generally arranged to use pressure control means to provide a pressure lower than atmospheric pressure to the pool water such that disinfectant byproducts dissolved in the pool water enters gaseous form, the degassing system further comprising means for separating the disinfectant byproducts in gaseous form from the pool water. The pressure control means may be arranged to provide suction.

[0054] The swimming pool 1 is in fluid communication with the recirculation system 2 and the degassing system 3. The recirculating system 2 and the degassing system 3 comprises suitable piping, conduits and pipes for connecting the various units of the systems described herein. The degassing system 3 may comprise an inlet pipe 4 for providing water from the recirculating system 2 and an outlet pipe 5 for providing water back to the recirculating system 2. However, in some embodiments, the degassing system 3 is connected to the swimming pool 1 separately from the pool recirculation system 2, such that the degassing system 2 has its own inlet 4 and outlet 5 to the swimming pool 1. Suitable connections on recirculation system 2 may be arranged to retrofit an existing recirculation system 2 with degassing system 3.In a preferred embodiment, the recirculating system 2 comprises a water adjustment module 31 and the degassing system 3 is provided upstream of the water adjustment module 31. An advantage with this is that the water is adjusted by water adjustment module 31 after being degassed, because degassing may remove some of the chlorine from the water.

[0055] In a preferred embodiment, the recirculation system 2 comprises a particle filter 30 and where the degassing system 3 is connected to the recirculating system 2 downstream of the particle filter 30. This has the advantage of providing pool water free of particles to the degassing system 3. Particles may otherwise damage the degassing system 3, for example damaging membrane 20.

[0056] The pressure provided by the pressure control means is selected such that disinfectant byproducts leave the pool water and enter gaseous form. The pressure provided by the pressure control means is preferably at most 0.6 ATA (absolute atmospheric pressure), more preferably at most 0.5 ATA, more preferably at most 0.4 ATA and most preferably at most 0.3 ATA. The pressure in the rest of swimming pool system 100 is generally around 1 ATM. In some embodiments, the disinfectant biproduct is a chlorinated disinfectant byproduct. In a preferred embodiment the chlorinated disinfectant byproduct is at least one of monochloramine (NH2CI) and dichloramine (NHCI2). In some embodiments at least monochloramine or dichloramine are caused to enter gaseous form in the degassing system 3. In some embodiments, trichloramine, THM or trichloromethane enters gaseous form in the degassing system 3. In some embodiments monochloramines or dichloramines other than monochloramine (NH2CI) or dichloramines other than or dichloramine (NHCI2) in general enters gaseous form. Without being bound by any theory, the balance between dichloramines in the water and gaseous trichloramine may be shifted towards the latter.

[0057] The pressure control means may be any suitable arrangement and may include a vacuum pump, for example a rotation pump or a positive displacement pump such as a piston pump. In various preferred embodiments, some of which are described in more detail below, the pressure control means comprises an ejector 7. An ejector 7 creates suction in a low-pressure inlet 43 using the Venturi effect. Ejector 7 has a high-pressure inlet 44 and an outlet45 with a nozzle arranged to provide suction at a low-pressure inlet 43, as is known in the art. Hence the ejector 7 may have a diffuser in the form of a funnel-shaped outlet 45.

[0058] When the pressure control means comprises an ejector 7, the pressure control means further comprises a pump 12 which provides flow of liquid through ejector 7. The pump 12 is arranged to provide flow thought the high-pressure inlet 44 and the outlet 45 of the ejector. The pump 12 is preferably arranged to provide liquid to the high-pressure inlet 44 of the ejector 7. An ejector 7 has the advantage of low cost and complexity and it is not sensitive to water in the same way as a for example a rotation pump.

[0059] The gas is separated from the pool water using means for separating the disinfectant byproducts in gaseous form from the pool water, and is ventilated from the system 3 using a ventilation conduit 8. The means for separating the disinfectant byproducts in gaseous form may comprise a vacuum chamber 9 or membrane 20 (see below). In some embodiments vacuum chamber 9 may provide retention so that gas is formed, for example as bubbles.

[0060] Gas is released from conduit 8 of degassing system 3 into the surroundings, for example to ventilation. Pressure control means may comprise means for equilibrating the pressure to the surroundings in order to release the gas into the surroundings, such as for example a valve

[0061] The degassing system 3 may comprise a gas sensor 14, for example arranged in conduit 8. The gas sensor 14 is arranged to detect the concentration or amount of disinfectant byproducts in gaseous form being isolated, separated or released by degassing system 3 such as trihalomethane, trichloromethane, monochloramine, dichloramine. The sensor 14 may be specific for one or more of the gases mentioned herein. The skilled person knows how to select a suitable gas sensor 14.

[0062] The means for separating the disinfectant byproducts in gaseous form from the pool water, may comprise means for separating gas bubbles from a liquid (a gas separator) such as a centrifugation separator 13 or a float de-airer. The means for separating gas bubbles froma liquid is preferably arranged downstream of the ejector 7. The means for separating gas bubbles from a liquid has an outlet for the liquid. When the liquid is pool water, the pool water is provided back the recirculation system 2 via outlet 5.

[0063] The degassing system 3 is arranged to draw water from recirculating system 2 in any suitable manner. In some embodiments all water from the recirculating system 2 enters the degassing system 3. In some embodiments, the degassing system is a circuit that is parallel to the recirculating system 2. For example, up to 20%, preferably up to 10 % of flow in the recirculating system 2 may be diverted to the degassing system 3. Hence in some embodiments, at least 1 % of the flow in the recirculating system 2 is diverted to the degassing system 3. In some embodiments, the degassing system 2 is in series with the recirculation system 2. In a preferred embodiment degassing occurs in a continuous process. In some embodiments, batch processing is used, where a volume of pool water is separated and subjected to low pressure. In various embodiments, degassing system 3 may be arranged to handle about from 0.5 m3water per hour to 100 m3water per hour.

[0064] Fig 2 shows a first embodiment of degassing system 3 adapted for batch processing of pool water. Here the pressure control means comprises a pump that is connected to a vacuum chamber 9. Valves 10 and 11 may be closed to isolate a batch of pool water in vacuum chamber 9. The vacuum pump is then activated to provide suction to vacuum chamber 9. Check valve 28 prevents backflow to vacuum chamber 9. As the pressure decreases, gas leaves the pool water and forms a gas fraction in vacuum chamber 9. Valve 10 is then opened to let in a new batch of pool water and to allow the gas to leave the degassing system 3 via the conduit 8. When the pool water in the batch has been sufficiently degassed, the batch of pool water is pumped back to the recirculation system 2. Vacuum chamber 9 is filled and emptied with pump 12. The degassing process can be monitored, for example with a gas sensor 14 or a pressure sensor that detects the pressure in the vacuum tank 9. The process is repeated with sufficient frequency to provide sufficient degassing of the pool water in system 100.Fig 3 shows a second embodiment. This embodiment is arranged for continuous degassing of pool water. Degassing system 3 comprises a membrane 20 for example comprised in a membrane unit 21. The membrane 20 is permeable to gases but non-permeable to water in liquid form. One suitable type of membrane is Liqui-Cel ™ provided by 3M. Pump 29 may control flow of water through degassing system 3 and thereby controls the flow through membrane unit 21.

[0065] The membrane 20 is arranged in the membrane unit 21 with a first side 41 in contact with the pool water and a second side 42 away from the pool water, where the pressure on the second side 42 of the membrane 20 is such that disinfectant byproducts dissolved in the pool water crosses the membrane, such that the disinfectant byproducts are in gaseous form on the second side 42 of the membrane. Preferably there is essentially no liquid water on the second side 42 of the membrane 20. The second side 42 of the membrane 20 may be referred to as the gas side of the membrane 20. The membrane 20 is advantageous because it provides possible to de-gas large volumes of pool water in an efficient manner. In Fig 3 the membrane unit 21 is arranged in parallel with the recirculation system 2, however, membrane unit 21 may be arranged in series in relation to the recirculation system 2.

[0066] Degassing system 3 moreover comprises a conduit 22 for removing the gas from the second side 42 of the membrane 20. The conduit 22 is connected to a pressure control means to provide suction to the second side 42 of the membrane 20.

[0067] The pressure control means in Fig 3 comprises an ejector 7 where the low-pressure inlet 43 of the ejector 7 is connected to the conduit 22. The disinfectant byproduct in gaseous form is provided to the low pressure inlet 43 of ejector 7 and mixed with a liquid that circulates in loop 23 to which the ejector 7 is connected. The liquid is preferably water. The circulation of liquid is driven by pump 12 which provides the liquid to the high pressure inlet 44 of the ejector 7. The disinfectant byproducts in gaseous form from the conduit 22 forms bubbles in the liquid. The outlet of the ejector 7 is connected to means for separating the gas bubbles from the liquid (gas separator), such as a de-aerator or a centrifugal gas separator 13 by conduit 27. The liquid and the gas are mixed in the ejector 7, such that the gas formsbubbles in the liquid. The gas and the liquid are lead via conduit 27 and separated in centrifugal separator 13. Gas is lead from the gas separated via the conduit 8, so that gas can be released. Pressure in the conduit 22 is controlled by pump 12 which controls the flow through the ejector 7, such that increasing flow through the ejector 7 deceases pressure in the conduit 22. Pressure control means is here provided as separate subsystem that is connected to rest of system 100 only via the conduit 22 and can be conveniently placed far away from the rest of degassing system 3. The dashed line in Fig 3 indicates that membrane unit 21 can be arranged at a distance from the rest of degassing system 3, such that they are only connected via conduit 22. This may provide flexibility when installing the degassing system 3 when the space is limited.

[0068] In Fig 3, the ejector 7 is provided in a loop 23 separate from the recirculation system 2. However, in some embodiments, pump 12 is connected in parallel with the recirculation system 2 causing water in the recirculation system 2 to be ejected from the ejector 7 to provide low pressure to the second side 42 of membrane 20. The ejector 7 is then arranged to eject pool water and the pool water is provided from the means for separating gas bubbles from the liquid back to the recirculation system 2 via outlet 5.

[0069] Figure 4 shows an embodiment of a degassing system 3 for continuous degassing of pool water. Here a membrane is not used. Instead, the disinfectant byproducts form bubbles in a second line 25 which may comprise a vacuum chamber 9. Water enters degassing system 3 through inlet 4 and is divided into a first line 24 and a second line 25. In first line 24 pump 12 draws water from the recirculating system 2 and provides it to the high pressure inlet 44 of ejector 7 where it is ejected. The low-pressure inlet 43 of the ejector 7 is connected to the second line 25. The second line 25 is arranged to draw pool water from recirculation system 2. The pressure in second line 25 is lower than in recirculation system 2 by being controlled in a suitable manner for example by a pressure reduction valve 26. The pressure reduction valve 26 may be controllable by a user so that user can select a suitable pressure. For example, from 1-10% of the water provided to degassing system 3 may be diverted to second line 25.The pressure is maintained in the second line 25 such that disinfectant byproducts dissolved in the pool water forms bubbles in the second line 25, for example in vacuum chamber 9. The skilled person realizes that other solutions for maintaining a low pressure in second line 26 than pressure reduction valve 26 is possible, such as, for example, a permanent flow restriction of the piping.

[0070] The gas is then provided to the ejector? via the low-pressure inlet 43 of the ejector?, where the gas is mixed with pool water from the first line 24 to form bubbles, and where the outlet 45 of the ejector 7 is connected to means for separating the gas bubbles from a liquid, for example centrifugal gas separator 13.

[0071] Hence the ejector 7 creates suction that draws pool water through second line 25 such that gas is formed in vacuum chamber 9. The gas is mixed with the pool water in the ejector 7 and separated using the means for separating the gas bubbles from a liquid.

[0072] In general and in various embodiments, the degassing system 3 is connectable to a swimming pool recirculating system 2, the degassing system comprising an ejector 7 having a low pressure inlet 43, and a pump 12 which provides flow of liquid through the ejector 7, the low pressure inlet 43 of the ejector 7 being connected to the recirculating system 3 such that disinfectant byproducts dissolved in the pool water forms bubbles in a liquid in the degassing system 3, the degassing system further comprising means for separating the gas bubbles from the liquid.

[0073] In various embodiments the degassing system 3 is reversible connectable to pool recirculation system 2, such that inlet 4 and outlet 5 are connectable to recirculation system 2. In various embodiments the degassing system 3 is provided in a vehicle, such as for example a truck. The vehicle is ambulatory and may connect to a pool system 100 in order to provide degassing of pool water, as needed. The degassing system 3 is then preferably arranged as a circuit that is parallel to the recirculation system 2.With reference to Fig 5, a method for removing disinfectant byproducts dissolved in swimming pool water comprises the steps 200 providing pool water to a degassing system 3, the degassing system at least comprising an inlet 4 providing pool water to the degassing system 3 and outlet 5 providing pool water from the degassing system, step 201 providing a pressure lower than atmospheric pressure to the swimming pool water in the degassing system 3 such that disinfectant byproducts dissolved in the pool water enters gaseous form, and 202 separating the disinfectant byproducts in gaseous form from the pool water.

[0074] Step 202 may involve separating the gas from the pool water, for example using a vacuum chamber 9 or membrane 20, then feeding the gas to the low pressure inlet 43 of ejector 7 whereby the gas forms bubbles in the liquid being ejected, and then using means for separating gas bubbles from a liquid, such as a centrifugation separator 13 or a float de-airer, to separate the gas bubbles from the liquid.

[0075] The skilled person understands how to control pressure in degassing system 3. The pressure or flow in system may be controlled, for example by controlling flow through the ejector 7, for example by controlling the rpm of the pump 12 or 29 in Fig 3 or by controlling the pressure control valve 26 in Fig 4. Pressure control valve 26 may be adjustable. The degassing system 3 may comprise a pressure sensor that measures pressure for example in vacuum chamber 9. Adjustments may be carried out manually or with the use of a control device such as control circuitry.

[0076] Example 1

[0077] A system as in Fig 3 was installed at the 25 meter-indoor swimming pool at Rosengardsbadet public bath, Malmo, Sweden. A membrane of type Liqui-Cel ™ provided by 3M was used. Ejectors were purchased provided by Grundfos, Denmark. The ejector was retrofitted with a low-pressure inlet by the inventors. Determination of trichloramine in air above the pool water surface and determination of bound chlorine in the pool water was carried out by gas chromatography carried out by the department of Environment and Health, OrebroUniversity, Sweden. After running the system, a remarkable decrease in trichloramine in the air above the pool surface was noted as well as a decrease in bound chlorine in the pool water.

Claims

CLAIMS1. Swimming pool system comprisinga swimming pool,a recirculating system coupled to the swimming pool for recirculating pool water, a degassing system connected to the recirculating system; the degassing system comprisingpressure control means for providing a pressure lower than atmospheric pressure to the pool water such that disinfectant byproducts dissolved in the pool water enters gaseous form, the degassing system further comprisingmeans for separating the disinfectant byproducts in gaseous form from the pool comprising a membrane unit, the membrane unit comprising a membrane that is permeable to gases and non-permeable to water in liquid form, the membrane being arranged with a first side in contact with the pool water, and where the pressure on a second side of the membrane is such that disinfectant byproducts dissolved in the pool water crosses the membrane as gas, and a conduit for removing the gas from the second side of the membrane.

2. The swimming pool system of claim 1 where the pressure control means comprises an ejector having a low-pressure inlet, the pressure control means further comprising a pump which provides flow of a liquid through the ejector, the ejector further comprising a high-pressure inlet and an outlet with a nozzle arranged to provide suction at the low-pressure inlet.

3. The swimming pool system of claim 2 where the low-pressure inlet of the ejector is connected to the conduit for removing gas from the second side of the membrane, such that disinfectant byproducts in gaseous form is provided to the ejector and mixed with the liquid such that the disinfectant byproducts in gaseous form forms bubbles in the liquid, and where the outlet of the ejector is connected to the means for separating the gas bubbles from a liquid.

4. The swimming pool system according to any one of claims 1 to 3 where the pressure provided to the pool water is lower than 0.6 ATM.

5. The swimming pool system according to any one of claims 1 to 4 where the degassing system comprises a gas sensor arranged to detect disinfectant byproducts in gaseous form that have been separated from the pool water.

6. The swimming pool system of any one of claims 1 to 5 where recirculation system comprises a particle filter and a water adjustment module said water adjustment module arranged to measure and adjust properties of the pool water and where the degassing system is connected to the recirculating system downstream of the particle filter and upstream of the water adjustment module.

7. A degassing system being connectable to a swimming pool recirculating system, the degassing system comprising an ejector having a low pressure inlet, and a pump which provides flow of liquid through the ejector, the low pressure inlet of the ejector being connectable to the recirculating system such that disinfectant byproducts dissolved in the pool water forms bubbles in a liquid in the degassing system, the degassing system further comprising means for separating the gas bubbles from the liquid being arranged downstream of the ejector,the degassing system further comprising a membrane unit comprising a membrane that is permeable to gases and non-permeable to water in liquid form, the membrane having a first side and a second side, the membrane being arranged with the first side in contact with the pool water, and where the second side of the membrane is connected to the low pressure inlet of the ejector with a conduit such that the pressure on the second side of the membrane is such that disinfectant byproducts dissolved in the pool water crosses the membrane as gas, where the conduit is arranged to lead the gas to the low pressure inlet of the ejector such that the gas forms bubbles in the liquid being ejected by the ejector, the degassing system further being arranged to provide the liquid with the bubbles to the means for separating the gas bubbles from a liquid.

8. A vehicle comprising a degassing system according to claim 7, where the degassing system is reversibly connectable to a swimming pool recirculation system.

9. A method for removing disinfectant byproducts dissolved in swimming pool water comprisinga) providing pool water to a degassing system, the degassing system at least comprising an inlet providing pool water to the degassing system and outlet providing pool water from the degassing system,b) providing a pressure lower than atmospheric pressure to the swimming pool water in the degassing system such that disinfectant byproducts dissolved in the pool water enter gaseous form,a) separating the disinfectant byproducts in gaseous form from the pool water, wherein the degassing system is as in claim 7.

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