Blackwater treatment device for recreational vehicles

Abstract

Blackwater treatment device for a recreational vehicle comprising a treatment vessel comprising a fluid inlet and a, preferably separate, fluid outlet; wherein the blackwater treatment device further comprises a temperature sensor arranged to provide a temperature signal based on a temperature of a content of the treatment vessel; a heating element arranged to heat the content of the treatment vessel based on the temperature signal for a predetermined amount of time; and wherein, during use, the heating element is arranged to heat blackwater provided in the treatment vessel to a disinfection temperature for the predetermined amount of time, thereby producing treated blackwater, wherein the disinfection temperature being sufficiently high for disinfecting of the blackwater and sufficiently low to prevent boiling of the blackwater.

Description

[0001] Title: Blackwater treatment device for recreational vehicles

[0002] The invention relates to a blackwater treatment device, the use of a blackwater treatment device and a recreational vehicle comprising a blackwater treatment device.

[0003] Recreational vehicles are a type of vehicle that combines transportation and living accommodation for recreational purposes. Such a recreational vehicle may be designed to comprise amenities found in a home, such as a sleeping area, a kitchen and a bathroom. Recreational vehicles can be road or sea based, e.g. motorhomes, travel trailers, camper vans, yachts, house boats and sailing boats. In general, wastewater coming from using a toilet, including using a toilet in a recreational vehicle, is called blackwater.

[0004] Blackwater comprises human waste, toilet paper and any other materials disposed of in the toilet. Blackwater is considered potentially dangerous due to the presence of various pathogens that are present in the fecal matter contained in the blackwater. These pathogens can cause diseases such as skin irritation, ear infections, gastroenteritis, dysentery, cholera, hepatitis, and other gastrointestinal infections when a person comes in to contact with the blackwater. In order to assess bacteriological contamination that may be caused by the presence of fecal matter in blackwater, the amount of indicator organisms present in blackwater are determined. Indicator organisms are microorganisms which are utilized as a surrogate to evaluate the presence of pathogens. An example such indicator organisms are Escherichia coli (E. coli) and intestinal enterococci.

[0005] Proper handling and disposal of blackwater are essential for maintaining hygiene, protecting the environment and abiding local regulations. For example, it may be unwanted to directly dispose of the blackwater in the surrounding of the recreational vehicle. Therefore, recreational vehicles that have a toilet also have a blackwater management system. A simple blackwater management system consists of a holding tank with a capacity that varies depending on the size and type of recreational vehicle. A disadvantage of a management system that only has a holding tank, is that the tank can only be emptied at designated pump-out stations. If the holding tank is full before reaching a pump-out station, the toilet can no longer be used.

[0006] In order to reduce dependency on pump-out stations, the blackwater management system may comprise a treatment system arranged to treat the blackwater, reducing the pathogens, such that the blackwater may be discharged to open water. However, a disadvantage of common treatment systems is that they are expensive, spacious and may use chemicals, e.g. chlorine, that negatively affect the environment. If the blackwater treated by such a treatment system is discarded directly to the environment, e.g. open water, these chemicals end up in the ecosystem, damaging it. A further disadvantage of present blackwater management systems is that they may contain filters. These filters may slowly clog, which can negatively affect the blackwater management system. Therefore, the filters need to be cleaned regularly, which may be an unpleasant experience for the person cleaning.

[0007] The invention aims to counteract the above disadvantages, preferably while retaining the advantages. More specifically, the invention aims to provide for a blackwater treatment device which allows for the treatment of blackwater such that it may be discarded to open water, without the need for an expensive and spacious system that may contain chemicals and I or filters.

[0008] Therefore, the invention provides for a recreational vehicle according to claim 1, comprising a blackwater treatment device arranged to treat blackwater. The blackwater treatment device comprises a treatment vessel comprising a fluid inlet and a, preferably separate, fluid outlet. The blackwater treatment device further comprises a temperature sensor arranged to provide a temperature signal based on a temperature of a content of the treatment vessel and a heating element arranged to heat the content of the treatment vessel based on the temperature signal for a predetermined amount of time. The heating element is arranged to, during use, heat the blackwater to a disinfection temperature for the predetermined amount of time, thereby producing treated, or disinfected, blackwater. The disinfection temperature is sufficiently high for disinfecting the blackwater such that sufficient bacteria are killed to allow safe discarding to open water and sufficiently low to prevent boiling of the blackwater. For example, the disinfection temperature can be between 70 and 100 degrees Celsius, preferably between 80 and 90 degrees Celsius, more preferably between 82 and 85 degrees Celsius. Optionally, the temperature sensor can be provided near the bottom of the treatment vessel, as it is expected that the temperature of the blackwater is lowest here when heating.

[0009] In the context of the invention, a recreational vehicle is understood to be a water or land based vehicle such as a boat or camper, that comprises facilities that produce blackwater as a waste source. In addition, it shall be understood that residential spaces provided on water, in which the toilet is not connected to a sewer system, are included within the context of ‘recreational vehicles’. In other words, a recreational vehicle according to the invention comprises a toilet.

[0010] The treatment vessel is made from a material suitable for containing blackwater, e.g. a material that is resistant to corrosion. Additionally, the vessel is sized such that it can be provided in existing recreational vehicles. For example, the treatment vessel may have a capacity that is 0.5 - 10 liter, preferably 1 -5 liter and more preferably 2 - 2.5 liter.

[0011] During use, blackwater is provided to the treatment vessel. The provided blackwater is heated to a temperature in a range between 70 - 100 degrees Celsius. Once the temperature of the blackwater is at such a temperature, it is kept there for a predetermined time. Such a predetermined time may be less than 30 minutes, preferably less than 15 minutes, more preferably 2 minutes or less. After this time, the blackwater is considered treated, i.e. the treatment vessel produced treated blackwater during this time. Due to the heating process, the pathogens that may have been present in the blackwater have been reduced to safe levels., for example safe levels for swimming regulations in open water. In particular, the presence of intestinal enterococci has been reduced to less than 330 cfu per 100 ml, based on a 90th percentile and analyzed according to NEN-EN- ISO 7899-1 or NEN-EN-ISO 7899-2 and the presence of Escherichia coli (E. coli) has been reduced to less than 900 cfu per 100 ml based on a 90th percentile and analyzed according to NEN-EN-ISO 9308-3 or NEN-EN-ISO 9308-1. Once the E. coli and intestinal enterococci content is below their respective upper limits, the blackwater is safe, for example safe for swimmers in open water, to be discharged. Providing heat in order to reduce pathogens, a cost efficient process has been facilitated that does not need chemicals or uses filters in order to treat blackwater such that it can be discharged in the environment.

[0012] In order to maintain the temperature of the blackwater in the preferred range in the treatment vessel, a heating element has been provided that is arranged to heat the blackwater based on a temperature signal that is provided by a temperature sensor. Preferably, the temperature sensor is provided at a location on the inside of the treatment vessel where it is expected that the blackwater is coldest. Since blackwater may not be a completely homogeneous liquid, i.e. the blackwater may comprise various components such as water, feces, paper, etc, a temperature gradient may arise when the blackwater is heated in the treatment vessel. Another cause of a temperature gradient, wherein the temperature is highest near the top of the treatment vessel, is the buoyancy of the blackwater that has a higher temperature than the blackwater that has a lower temperature, e.g. the blackwater that is not heated yet. By controlling the heating of the heating element based on the temperature of the coldest region of the treatment vessel it is ensured that the complete batch of blackwater is sufficiently heated to remove pathogens.

[0013] In order to facilitate homogenization of the blackwater, the recreational vehicle can comprise a macerator provided in fluid communication with, and optionally upstream of, the treatment vessel. Alternatively, the macerator may be provided in a closed loop that is in fluid communication with the buffer tank such that blackwater can be transported from the buffer tank, through the macerator, back in to the buffer tank. The macerator may be arranged to substantially homogenize the structural properties of the blackwater, for example by shredding the toilet paper and reducing the size of fecal matter. This may facilitate better throughout heating, i.e. ensuring that all of the blackwater reaches a sufficiently high temperature, as large clumps of matter in blackwater may take significantly longer to heat.

[0014] The heating element can be provided on the outside of the treatment vessel, preferably the heating element is provided near the bottom and around the perimeter of the treatment vessel. Since warm liquid tends to buoyance, i.e. it will float towards the top of the treatment vessel, heating the bottom of the treatment vessel may produce a substantially equally heated blackwater. In other words, the temperature gradient throughout the blackwater during treatment remains relatively flat. This may allow for a more easily and reliable controlled heating process.

[0015] As an alternative, the bottom of the treatment vessel can comprise the heating element. Or in other words, the heating element may be integrated in the bottom of the treatment vessel. For example, the bottom of the treatment vessel may comprise a grove, in which a flexible heating element is provided. By having a bottom area of the treatment vessel that comprises a heating element, or alternatively is the heating element, as opposed to providing an external heating element, the blackwater may be heated more efficiently. Since warm liquid tends to buoyance, i.e. it will float towards the top of the treatment vessel, heating the bottom of the treatment vessel may produce a substantially equally heated blackwater. In other words, the temperature gradient throughout the blackwater during treatment remains relatively flat. This may allow for a more easily and reliable controlled heating process.

[0016] Additionally or alternatively, the heating element can comprise a heat exchanger. Such a heat exchanger may be used to preheat the blackwater entering the treatment vessel, thereby reducing energy that the heating element needs to provide. The heat exchanger can be arranged to heat a cold fluid using a hot fluid while the cold fluid and hot fluid remain separated. The cold fluid can be the content of the treatment vessel, e.g. the blackwater; the hot fluid can be treated blackwater as this has a higher temperature than the untreated blackwater. In an even further example, the hot fluid can be a coolant from an engine of the recreational vehicle. This may provide sufficiently heat to the treatment vessel, that there may be no need for an external heating element, rendering the blackwater treatment device even further energy efficient. However, if the coolant from an engine does not provide sufficient heat an external heating element may be provided.

[0017] The treatment vessel can further comprise a level sensor arranged to determine a fluid level of blackwater present in the treatment vessel and provide a fluid level signal accordingly. Such a level sensor can be used to control blackwater flow to and from the treatment vessel, and may both act as means to automatize the blackwater treatment system and as a safeguard that prevents overflowing of the treatment vessel.

[0018] The recreational vehicle can further comprise a buffer tank provided upstream of and in fluid communication with the treatment vessel and a first pump arranged to pump blackwater from the buffer tank to the treatment vessel. Optionally, the recreational vehicle can comprise a toilet provided upstream of the buffer tank. Providing a buffer tank between the source of the blackwater, e.g. the toilet, and the treatment vessel may allow for the treatment of blackwater at any time and not just when a toilet has been used. For example, it may be possible to use a toilet multiple times and storing the blackwater in the buffer vessel. Next, at a preferred time, the treatment of the blackwater can begin. This may be advantageous when energy is not sufficiently available for treatment of the blackwater on the recreational vehicle at all times, e.g. a sailing boat.

[0019] The buffer tank can comprise a liquid level sensor and an audible and I or visible alarm. The liquid level sensor can be arranged to provide a liquid level signal. The alarm may go off based on the liquid level sensor, for example when the buffer tank is close to being full. Such an alarm may be provided on the blackwater treatment device, but also elsewhere in the recreational vehicle.

[0020] The treatment vessel can further comprise a vent provided near the top of the treatment vessel arranged to substantially maintain a constant pressure in the treatment vessel. A vent may facilitate that no over or under pressure arises in the treatment vessel due to supplying, heating or removing the blackwater during the treatment cycle.

[0021] The buffer tank can further comprise a vent provided near the top of the buffer tank arranged to substantially maintain a constant pressure in the buffer tank. Preferably, the vent can comprise a filter arranged to prevent odorous particles from leaving the blackwater treatment device. In a second aspect of the invention, a method of producing treated blackwater using a recreational vehicle is provided. The method comprises the steps of:

[0022] - providing a recreational vehicle comprising a blackwater treatment device according to any of the preceding claims; - heating the blackwater in the treatment device to a temperature between 70 and 100 degrees Celsius, preferably between 80 and 90 degrees Celsius, more preferably between 82 and 85 degrees Celsius;

[0023] - maintain, after heating the blackwater, the temperature of the blackwater in the treatment device for a predetermined amount of time, thereby producing treated blackwater, wherein the treated blackwater comprises less than 330 cfu intestinal enterococci per 100 ml, based on a 90th percentile and analyzed according to NEN-EN-ISO 7899-1 or NEN-EN- ISO 7899-2, and less than 900 cfu Escherichia coli (E. coli) per 100 ml based on a 90th percentile and analyzed according to NEN-EN-ISO 9308-3 or NEN-EN-ISO 9308-1.

[0024] In a third aspect of the invention, a blackwater treatment device for a recreational vehicle is provided. The blackwater treatment device comprises a treatment vessel comprising a fluid inlet and a, preferably separate, fluid outlet. The blackwater treatment device further comprises a temperature sensor arranged to provide a temperature signal based on a temperature of a content of the treatment vessel and a heating element arranged to heat the content of the treatment vessel based on the temperature signal for a predetermined amount of time. The heating element is arranged to, during use, heat the blackwater to a disinfection temperature for a predetermined time, thereby producing treated, or disinfected, blackwater. The disinfection temperature is sufficiently high for disinfecting the blackwater such that sufficient bacteria are killed to allow safe discarding to open water and sufficiently low to prevent boiling of the blackwater. Heating and boiling of blackwater may result in the formation of steam and foam, which may be damage the blackwater treatment device or other components of the recreational vehicle. For example, the disinfection temperature can be between 70 and 100 degrees Celsius, preferably between 80 and 90 degrees Celsius, more preferably between 82 and 85 degrees Celsius. The technical features described in the paragraphs and sentences above can be isolated from the context, and the isolated technical features from the different paragraphs and sentences can be combined. Such combinations are herewith specifically disclosed in this description.

[0025] The invention will further be elucidated on the basis of exemplary embodiments which are represented in the drawings. The exemplary embodiments are given by way of non-limitative illustration of the invention.

[0026] In the drawings:

[0027] Fig. 1 depicts a schematic view of an example of a recreational vehicle according to an example of the invention;

[0028] Fig. 2 depicts a schematic side view of a treatment vessel according to an example of the invention;

[0029] Fig. 3 depicts a schematic view of a further example of a recreational vehicle according to an example of the invention;

[0030] Fig. 4A depicts a schematic side view of a treatment vessel according to a further example of the intervention;

[0031] Fig. 4B an isometric view of an example of a bottom of the treatment vessel depicted in Fig. 4A.

[0032] Turning to Fig. 1, a schematic view of a recreational vehicle according to an example of the invention is depicted. In the example, the recreational vehicle is a boat 100, depicted by a schematic cross section of the boats hull 101. In the boat 100, a blackwater treatment device is provided 200 comprising a toilet 1 is provided. When the toilet 1 is flushed, water from the toilet 1 is transported from the toilet 1 to a buffer tank 4, via conduits. In the shown figures, conduits are depicted by arrows that go from one component to the next. The direction of the arrows depict the direction of the flow, i.e. an arrow points from an upstream component towards a downstream component. Solid arrows depict conduits that are substantially used for transporting liquids, dashed arrows depicts conduits that are substantially used for transporting gas. The conduits may be provided as piping, for example piping made from plastics or rubber.

[0033] In the example, toilet 1 is connected to the buffer tank 4 via a first pump 2. Said first pump 2 may facilitate the flow of blackwater towards the buffer tank 4. However, it will be clear to the person skilled in the art that, if sufficient flushing water is provided to the toilet 1, such a first pump 2 may not be needed. Alternatively, pump 2 may be part of a ship toilet. Additionally, in the example a macerator 3 has been provided, in fluid communication with the buffer tank 4. The macerator 3 may comprise a pump, such that blackwater present in the buffer tank 4 may be pumped through the macerator 3 back in to the buffer tank 4. . The macerator 3 is used to reduce the size of solids that may be present in the blackwater, for example toilet paper or large clumps of fecal matter, thereby providing a more homogenous liquid. While the use of a macerator 3 may result in a more homogenous blackwater substance, that may be heated more uniform, it is understood that a macerator 3 is an optional but advantageous feature.

[0034] Downstream of the first pump 2 a first buffer tank 4 is provided. Multiple batches of blackwater produced by using, and specifically flushing, the toilet 1 multiple times can be stored in the first buffer tank 4. The buffer tank comprises a liquid level sensor that is arranged to provide a liquid level signal. The liquid level signal can be used to produce an audible and I or visible alarm in the control room, e.g. in the steering cabin, of the boat if a predetermined value is reached. In particular, the predetermined value can be used to indicate that the buffer tank 4 is close to being full.

[0035] Blackwater that is to be treated is pumped from the buffer tank 4 to the treatment vessel 20. The blackwater enters the treatment vessel 20 via a fluid inlet 21 and, once treated, leaves the blackwater treatment vessel via fluid inlet 22, both of which are shown in Fig. 2. The blackwater treatment device 200 comprises a temperature signal in the treatment vessel 20 arranged to provide a temperature signal indicative of the temperature of the content in the treatment vessel 20, which is blackwater during use. The temperature sensor is provided near the bottom 27 of the treatment vessel 20, as it is expected that the temperature of the blackwater is lowest here. Therefore, the temperature sensor can give a good indication of the lowest temperature of the blackwater in the treatment vessel 20, thereby ensuring that all of the blackwater reaches a minimum temperature for at least the predetermined time.

[0036] Heating element 23, shown in Fig. 2, is arranged to heat the content of the treatment vessel 20 based on the temperature signal. In the shown example, the blackwater is treated by heating the blackwater to a minimum temperature of 80 degrees Celsius for a predetermined period of two minutes. Once the blackwater is provided to the treatment vessel 20, and a treatment cycle starts, the heating element 23 keeps heating until a setpoint near 80 degrees Celsius is achieved. The heating element 23 then stops heating. The temperature is then monitored for the predetermined time of two minutes. If the temperature drops too far, e.g. reaching 79 or 78 degrees Celsius, further heat is provided until the setpoint is reached again. Once two minutes have passed, and the temperature was maintained, treatment of the blackwater is finished and no further heating by the heating element 23 is needed for this batch. The resulting treated blackwater is provided to a second buffer tank 7 via third pump 6.

[0037] The treatment vessel 20 has a level sensor arranged to determine the fluid level of blackwater present in the treatment vessel and provide a fluid signal accordingly. The signal can be to control the second pump 5 supplying blackwater to the treatment vessel 20 and control the third pump 6 that is used to transport treated blackwater to a second buffer tank 7. In particular, the level sensor can be used to stop the second pump 5 pumping blackwater towards the treatment vessel 20 when the vessel close to being full and to stop the third pump 6 from pumping blackwater out of the treatment vessel 20 when the vessel is almost empty, thereby preventing cavitation.

[0038] In the shown example, the treated blackwater can be stored in the optional second buffer tank 7. While the treated blackwater is allowed to be discharged on open water, it may still be preferred to discharge the treated blackwater at different times. For example, blackwater may be treated while the boat is laying at a pier, next to other boats. In such a scenario, it may be preferred to store the treated blackwater in the second buffer tank 7 instead of immediately discharging the treated blackwater. The treated blackwater may be removed from the second buffer tank using a fourth pump 8. In the shown example, a closeable opening 9 is provided in the hull 101 of the boat through which the treated blackwater can be discharged.

[0039] The closeable opening 9 is provided on the hull 101 at a location that, during use, is under water. Alternatively, closeable opening 9 may be provided above water during use.

[0040] In the shown example, both buffer tanks 4, 7 and the treatment vessel 20 with an opening near the top of the corresponding buffer tanks 4, 7 and treatment vessel 20 that is in fluid communication with a vent 10. The vent is provided at a higher location that buffer tanks 4, 7 and the treatment vessel 20, such as for example a roof of the boat 100 (not depicted). Providing a vent 10, prevents the treatment vessel 20 and buffer tanks 4, 7 from having an over pressure or under pressure. In the shown example, all three components are connected to one vent 10, but it shall be clear to the person skilled in the art that any number of vents may be used, including vents already present on the recreational vehicle.

[0041] Fig. 2 depicts a schematic cross-sectional side view of a treatment vessel 20 according to an example of the invention. The treatment vessel has a fluid inlet 21 and fluid outlet 22 that are arranged to connect to the upstream and downstream components of the blackwater treatment device 200, for example by a flanged connection. Outlet 22 has a standing pipe that extends in to the treatment vessel 20. Near the bottom 27 of the treatment vessel, i.e. opposite the fluid inlet 21 and fluid outlet 22, the temperature sensor 25 is provided as well as the heating element 23. In the depicted example, the heating element is provided on the outside of the treatment vessel 23. Furthermore the heating element 23 is provided in a circumferential direction around the treatment vessel 20. In the shown example, the heating element 23 is provided as an electrically powered heating element 23. A level sensor 26 is provided in the treatment vessel 20. Finally, the treatment vessel 20 comprises a vent connection 24, arranged to form a fluid connection with the vent 10, which is depicted in Fig. 1.

[0042] Fig. 3 shows a further example of the invention. In the schematic view, the treated blackwater enters a heat exchanger 11, via pump 6 before being discarded from the boat via closeable opening 9. The treated blackwater is of a relatively high temperature, compared to the pre-treated blackwater, and thus can be used to pre-heat the blackwater that has yet to enter the treatment vessel 20. In other words, the blackwater that is being pumped to the treatment vessel 20 by second pump 5, passes through a heat exchanger 11 before entering the treatment vessel 20. A previous batch of treated blackwater also passes the heat exchanger 11 at the same time, before being discard through closeable opening 9 in the hull 101. Due to the heat exchanger 11, the treated blackwater reduces in temperature while the untreated blackwater increases in temperature. This example is considered advantageous over the example of Fig. 1, as less energy is required to heat the blackwater in the treatment vessel 20. Additionally or alternately, the heat exchanger 11 may be provided in the buffer tank 4, such that the black water present in the buffer tank 4 can be heated before being pumped to the treatment vessel 20. This may be advantageous as space is saved by integrating the heat exchanger 11 in the buffer tank 4. It shall also be clear that if a different source is used to heat the blackwater in the heat exchanger 11, for example coolant used by an engine of a recreational vehicle, a further heating element 23 may not be needed. Such an embodiment would further improve energy efficiency of the blackwater treatment device 200. While no second buffer tank is depicted, it shall be clear to the person skilled in the art, that this example could also have comprised a second buffer tank.

[0043] In both examples, when the blackwater leaves the treatment vessel 20, i.e. the treated blackwater, comprises less than 330 cfu intestinal enterococci per 100 ml, based on a 90th percentile and analyzed according to NEN-EN-ISO 7899-1 or NEN-EN-ISO 7899-2, and less than 900 cfu Escherichia coli (E. coli) per 100 ml based on a 90th percentile and analyzed according to NEN-EN-ISO 9308-3 or NEN-EN-ISO 9308-1.

[0044] Referring to Fig. 4A and 4B, a further example of treatment vessel 20 is shown. In this example, the heating element 23 is provided integrated in the bottom 27 of the treatment vessel 23. More specifically, the bottom 27 of the treatment vessel comprises a spirally shaped grove 28, in which a flexible heating element 23 is provided. A cover, covering the grove containing the heating element 23, is provided such that the heating element 23 remains in position. Furthermore, the cover is made out of a material, e.g. steel, in order to facilitate heat conductivity between the heating element 23 and the contents of the treatment vessel 20, e.g. blackwater. Since warm liquid tends to buoyance, i.e. it will float towards the top of the treatment vessel 23, heating at the bottom 27 of the treatment vessel 23 may produce a substantially equally heated blackwater. In other words, the temperature gradient throughout the blackwater during treatment remains relatively flat. This may allow for a more easily and reliable controlled heating process.

[0045] Many variations will be apparent to the skilled person in the art. Such variations are understood to be comprised within the scope of the invention as defined in the appended claims.

Claims

Claims1. Recreational vehicle, in particular a boat, comprising a blackwater treatment device arranged to treat blackwater, wherein the blackwater treatment device comprises a treatment vessel comprising a fluid inlet and a, preferably separate, fluid outlet; wherein the blackwater treatment device further comprises a temperature sensor arranged to provide a temperature signal based on a temperature of a content of the treatment vessel; a heating element arranged to heat the content of the treatment vessel based on the temperature signal for a predetermined amount of time; and wherein the heating element is arranged to, during use, heat the blackwater to a disinfection temperature for the predetermined amount of time, thereby producing treated blackwater, wherein the disinfection temperature is sufficiently high for substantial disinfection of the blackwater and sufficiently low to prevent boiling of the blackwater.

2. Recreational vehicle according to claim 1, wherein the treatment vessel further comprises a level sensor arranged to determine a fluid level of blackwater present in the treatment vessel and provide a fluid level signal accordingly.

3. Recreational vehicle according to claim 1 or 2, wherein the treatment vessel further comprises a vent provided near the top of the treatment vessel arranged to substantially maintain a constant pressure in the treatment vessel.

4. Recreational vehicle according to any of the preceding claims, wherein the heating element is provided on the outside of the treatment vessel.

5. Recreational vehicle according to any of the preceding claims, wherein the heating element is provided near the bottom and around the perimeter of the treatment vessel.

6. Recreational vehicle according to any one of the claims 1-4, wherein the bottom of the treatment vessel comprises the heating element.

7. Recreational vehicle according to any one of the claims 1-4, wherein the blackwater treatment device further comprises a heat exchanger and wherein the heat exchanger is arranged to heat a cold fluid using a hot fluid while the cold fluid and hot fluid remain separated, wherein the cold fluid is the content of the treatment vessel.

8. Recreational vehicle according to claim 7, wherein the hot fluid is treated blackwater.

9. Recreational vehicle according to claim 7, wherein the hot fluid is a coolant from an engine of the recreational vehicle.

10. Recreational vehicle according to any of the preceding claims, further comprising a buffer tank provided upstream of and in fluid communication with the treatment vessel and a first pump arranged to pump blackwater from the buffer tank to the treatment vessel.

11. Recreational vehicle according to claim 10, further comprising a macerator in fluid communication with the buffer tank, said macerator arranged to substantially homogenize the structural properties of the blackwater.

12. Recreational vehicle according to any of the preceding claims, further comprising a toilet provided upstream of the blackwater treatment device.

13. Recreational vehicle according to claim 11 or 12, wherein the buffer tank comprises a liquid level sensor and an audible and I or visible alarm, wherein the liquid level sensor is arranged to provide a liquid level signal; and wherein the audible and I or visible alarm is activated when the liquid level signal is above a predetermined liquid level value.

14. Recreational vehicle according to any of the preceding claims, wherein the buffer tank further comprises a vent provided near the top of the buffer tank arranged to substantially maintain a constant pressure in the buffer tank.

15. Recreational vehicle according to claim 14, where the vent comprises a filter arranged to prevent odorous particles from leaving the blackwater treatment device.

16. Recreational vehicle according to any of the preceding claims, wherein the temperature sensor is provided near the bottom of the treatment vessel.

17. Recreational vehicle according to any of the preceding claims, wherein the heating element is arranged to heat the blackwater to a disinfection temperature that is during use between 70 and 100 degrees Celsius, preferably between 80 and 90 degrees Celsius, more preferably between 82 and 85 degrees Celsius.

18. Method of producing treated blackwater using a recreational vehicle comprising the steps of:- providing a recreational vehicle comprising a blackwater treatment device according to any of the preceding claims;- heating the blackwater in the treatment device to a temperature between 70 and 100 degrees Celsius, preferably between 80 and 90 degrees Celsius, more preferably between 82 and 85 degrees Celsius;- maintain, after heating the blackwater, the temperature of the blackwater in the treatment device for a predetermined amount of time, thereby producing treated blackwater, wherein the treated blackwater comprises less than 330 cfu intestinal enterococci per 100 ml, based on a 90th percentile and analyzed according to NEN-EN-ISO 7899-1 or NEN-EN- ISO 7899-2, and less than 900 cfu Escherichia coli (E. coli) per 100 ml based on a 90th percentile and analyzed according to NEN-EN-ISO 9308-3 or NEN-EN-ISO 9308-1.

19. Blackwater treatment device for a recreational vehicle comprising a treatment vessel comprising a fluid inlet and a, preferably separate, fluid outlet; wherein the blackwater treatment device further comprises a temperature sensor arranged to provide a temperature signal based on a temperature of a content of the treatment vessel; a heating element arranged to heat the content of the treatment vessel based on the temperature signal for a predetermined amount of time; and wherein, during use, the heating element is arranged to heat blackwater provided in the treatment vessel to a disinfection temperature for the predetermined amount of time, thereby producing treated blackwater, wherein the disinfection temperature being sufficiently high for disinfecting of the blackwater and sufficiently low to prevent boiling of the blackwater.

20. Blackwater treatment device according to claim 19, wherein the heating element is arranged to heat the blackwater to a disinfection temperature that is during use between 70 and 100 degrees Celsius, preferably between 80 and 90 degrees Celsius, more preferably between 82 and 85 degrees Celsius.

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