WO2024089211A1

WO2024089211A1 - System and method for treatment of wastewater.

Info

Publication number: WO2024089211A1
Application number: PCT/EP2023/080000
Authority: WO
Inventors: Halfdan KVERNELAND OLAFSSØN; André Robert HOLT OLAFSSØN
Original assignee: Blueshift As
Priority date: 2022-10-27
Filing date: 2023-10-26
Publication date: 2024-05-02
Also published as: NO20221154A1

Abstract

A system for treatment of wastewater comprising a filtering unit for filtering out particles over a certain size from the wastewater, at least one UVC light source exposing the filtered wastewater to UVC light over a certain energy level, characterized in that the wastewater is sent in a turbulent flow around the at least one UVC light sources.

Description

System and method for treatment of wastewater.

The present invention regards a system and a method for treatment of wastewater. And more particularly a system and method for using UV light to treat wastewater.

Background of the invention

UV is an electromagnetic radiation with the wavelength from 10 nm to 400 nm. UV light therefore has longer wavelength than X-rays, but shorter than visible light. The sun bombards the earth with UV-light all the time. Here on earth common sources for UV light are electric arcs and specialized lights like mercury-vapor lamps, tanning lamps, black lights, and some LEDs.

UV light is divided into three different categories which are UVA, UVB and UVC. UVA has a wavelength of 315-400 nm and is considered as long wave UV light and is common in e.g. black lights. UVB has a wavelength of 280-315 nm and is called medium wave UV light. On Earth the most of the UVB light is absorbed by the ozone layer.

UVC is what we call a short-wave UV light and is completely absorbed by the ozone layer. UVC is also germicidal and is used in UVGI (UltraViolet Germicidal Irradiation). UVGI is a disinfection method that uses UVC light to kill or inactivate microorganisms by destroying the nucleic acids and their DNA. UVGI is used in a variety of applications, such as food, air, and water purification.

UVGI has been used since about 1910, and was first used in Marseilles, France to sterilize drinking water. This first sterilization plant was shut down after a short time due to unreliable results. Since around 1955 it has been used primarily to sterilize medical equipment and work facilities. Lately UVGI has been used more and more as a method for disinfecting drinking water and to treat wastewater.

There are several advantages of UV treatment over other water disinfection systems in terms of cost, labor, and the need for technically trained personnel for operation. Water chlorination treats larger organisms and offers residual disinfection, but these systems are expensive due to the need of special operator training and a steady supply of a potentially hazardous material. The boiling of water is the most reliable treatment method, but it demands a lot of labor, and has a high economic cost. UV treatment is rapid and, in terms of primary energy use, approximately 20,000 times more efficient than boiling.

However, there are certain disadvantages with using UV disinfection. It is most effective for treating high clarity, purified reverse osmosis distilled water. Suspended particles are a problem because microorganisms buried within particles are shielded from the UV light and pass through the unit unaffected. However, UV systems are usually coupled with a pre-filter to remove those larger organisms that would otherwise pass through the UV system unaffected. The pre-filter also clarifies the water to improve light transmittance and therefore UV dose throughout the entire water column. Another key factor of UV water treatment is the flow rate, if the flow is too high, water will pass through without sufficient UV exposure. If the flow is too low, heat may build up and damage the UV lamp.

The use of ultraviolet light in sewage treatment is commonly replacing chlorination. This is in large part because of concerns that reaction of the chlorine with organic compounds in the wastewater stream could synthesize potentially toxic and long-lasting chlorinated organics and also because of the environmental risks of storing chlorine gas or chlorine containing chemicals.

A further benefit of using UV light to treat wastewater is that is destroys microorganisms even if they are resistant to antibiotics or other antimicrobials. Hospitals, veterinary clinics, and similar institutions are therefore installing more and more UV light treatment systems in order to kill microorganisms before they are released into the environment.

One such wastewater treatment facility has been developed at Herlev Hospital in Copenhagen Denmark. A problem with facilities such as these is that for the UV-light to be effective, the wastewater needs to be filtered down to particles no more than 0.2 pm before the water is exposed to the UV light. This filtration process is very demanding, slow and expensive. At the Herlev hospital the filtered wastewater is exposed to UV light with the energy of 5-10 joules/liter.

Some classes of antibiotics are sensitive to UVA and UVB light, breaking them down over time. Other classes, however, such as the quinolones, have extremely limited susceptibility to UVA and UVB light, resulting in such antibiotics lingering in the environment and contributing disproportionately to the development of antibiotic resistance. Doses of UVC light greater than 2000 joules per liter, however, are capable of breaking down antibiotics, such as the quinolone Ciprofloxacin. This prevents these antibiotics from contributing to the development of antibiotic resistance when released into the environment via sewage or wastewater.

Summary of the invention

It is an object of the present invention as stated in the present set of claims to solve the problems mentioned above.

The first aspect of the present invention regards a system for treating water comprising a filtering unit the water flows through for filtering out particles over a certain size from the water, an ozone chambre for ozonating the water and a treatment chambre with at least one UV light source exposing the filtered water to UV light, wherein, the water is sent in a turbulent flow around the at least one UV light source.

Further the filtering unit may filter out particles over the size of 0.5-1 mm, also the filtering unit can be in the form of a mesh screen, or the filtering unit can be in the form of a tumbler with a mesh screen that filters the water and the filtered-out material is transported to a dumping area using an Archimedes screw, further the filtering unit can be in the form of a settling tank.

The UV light source can emit light with a wavelength range of 100-280 nm, and the shape of the UV light source can be an elongated lightbulb.

The treatment chamber may have a plurality of UV light sources placed parallel to each other and spaced apart at regular intervals, also the UV light sources can be placed inside cylindrical tubes inside the treatment chambre through which the water flows through.

The water can be sent through the treatment chambre in a turbulent flow and the turbulent flow can be created by at least one inlet nozzle.

Further the water can be subjected to a UV-dosage within the range of 500-5000 joules/liter, however the water can more preferably be subjected to a UV-dosage within the preferred range of 2000-3000 joules/liter.

The second aspect of the present invention regards a method for treating water may comprise the following steps: filtering out particles from the water over a certain size using a filtering unit, ozonating the water using an ozone chambre, exposing the filtered water to UV light from at least one UV light source over a certain energy level, sending the water in a turbulent flow around the at least one UVC light source.

The water may be subjected to a UV-dosage within the range of 500-5000 joules/liter, however it may more preferably be subjected to a UV-dosage within the range of 2000- 3000 joules/liter, and the turbulent flow may be created using an inlet nozzle.

The capability in treating wastewater with particles of this size greatly reduces the cost of the system and the size of the system. A benefit is a wastewater treatment system that is affordable small in space and that can be installed in in a wide variety of places that previously did not have the possibility of installing such a system. Brief description of the drawings

Fig. 1 is a block diagram of the process in the present invention.

Fig. 2 is an exploded image of the UVC unit of the present invention.

Fig. 3 is an image of the results of DNA being exposed to UV-light.

Fig. 4 a-c is images of different embodiments of the filtering unit of the present invention.

Detailed description

Fig. 1 is a block diagram of the process in the present invention.

The first step in the process is a source of wastewater. An example of typical wastewater can be the water used by a hospital or a similar place where there is a possibility that antibiotic resistant bacteria and antibiotics can end up being sent to the sewer system. A problem with antibiotic resistant bacteria and antibiotics entering the sewer system is that the water from human activities is collected at wastewater treatment plants where processes often do not sufficiently neutralize antibiotic resistant bacteria, antibiotic resistant genes, and antibiotics. This can further be sent into the local environment where it can find its way back to humans, exacerbating the issue of antibiotic resistance.

In the first step the wastewater from the hospital or a similar is guided into a settling tank. In this settling tank sediments settle at the bottom of the tank and the remaining water, called grey water, is pumped to the next step. The reason for this step is to ensure that the sediments in the wastewater do not hinder the effect of the UVC light.

In the second step the grey water is filtered through a mechanical separating mesh. There are many ways of filtering the greywater. However, one preferred way is to use a tumbler connected to an Archimedes screw. The tumbler has a large opening in one end through which the wastewater flows into. As the tumbler rotates and the water flows through the side of the tumbler, the water is filtered. The side of the tumbler is comprised of a mesh screen. The tumbler with the mesh screen and the Archimedes screw is called the filtering unit. The filtering unit filters out particles over a predetermined size. A typical, and preferred, filtering size is 0.5-1 mm.

The filtered particles are transported out of the top of the tumbler via an Archimedes screw and into a collecting bin. The sediments from the settling tank and the filtered particles are transported can be transported to an incineration unit, the incineration unit kills any bacteria and viruses that might be in the particles in the wastewater.

The third step of the process is an ozone chambre. The ozone chambre is for ozonating the water. When ozone is added to water, it dissolves contaminants without changing the composition of the water. Further, it does not introduce anything to the water like that kills bacteria or anything that leaves a smell. The ozonation method is highly effective in killing bacteria, viruses, and other microorganisms that contaminate water and can lead to cancers and other related illnesses.

The fourth and last step of the process is to send the grey water into a machine that exposes the wastewater to UVC light that kills the rest of the bacteria or viruses that might be alive, or renders the rest of the bacteria or the viruses that might be alive unable to reproduce.

The UVC treatment of the wastewater happens in a UVC treatment chamber. The UVC treatment chambre is comprised of at least one elongated light source that emits UVC light. In a preferred solution of the present invention the UVC treatment chambre is comprised of a plurality of elongated light sources that emits UVC light. The elongated UVC light sources are spaced apart to allow the grey water to flow around the elongated light sources. The plurality of elongated light sources spaced apart in the UVC treatment chambre ensures that the system is capable of handling rather large quantities of water, like the normal amount of wastewater from a hospital.

Further the wastewater is sent in a turbulent flow around the elongated UVC light sources. The turbulent flow is made possible by pressurized movement of the wastewater through a cylindrical reactor with an annulated or a spiral internal geometry, forcing a disturbance in the flow of the water around the at least one elongated UV light source.

The pressurized movement of the wastewater through the cylindrical reactor with an annulated or a spiral internal geometry is preferably between the range of 5-10 bar. This result in the movement of the wastewater of between 0.5-3 m/s. The disturbance this causes in the wastewater is ideally between 7000-8000 Reynolds.

The disturbance in the wastewater ensures that the UVC light rays has a higher penetrating ability through the wastewater than would normally be possible with the wastewater not flowing in a turbulent flow. The higher penetrating ability of the UVC light rays ensures that larger amounts of water can be treated faster than with the present invention. The wastewater can be subjected to a UV-dosage within the range of 500-5000 joules/liter. However, in a preferred embodiment of the present invention the wastewater is subjected to a UV-dosage within the range of 2000-3000 joules/liter.

The final step of the process is to dump the treated wastewater into the sewer system.

Fig. 2 is an exploded image of the UVC treatment chamber of the present invention. This chamber is comprised of at least one UVC light source. In a preferred embodiment of the present invention there are a plurality of UVC light sources.

The elongated UVC light sources are spaced apart in order to allow the grey water to flow around the elongated light sources. The plurality of elongated light sources spaced apart in the UVC treatment chambre ensures that the system is capable of handling rather large quantities of water, like the normal amount of wastewater from a hospital.

These elongated UVC light sources are preferably placed in a matrix. The gray water is sent in a turbulent flow around the UVC light sources.

The turbulent flow is made possible by pressurized movement of the wastewater through a cylindrical reactor with an annulated or a spiral internal geometry, forcing a disturbance in the flow of the water around the at least one elongated UV light source.

The disturbance in the wastewater ensures that the UVC light rays has a higher penetrating ability through the wastewater than would normally be possible with the wastewater not flowing in a turbulent flow. The higher penetrating ability of the UVC light rays ensures that larger amounts of water can be treated faster than with the present invention.

The wastewater can be subjected to a UV-dosage within the range of 500-5000 joules/liter. However, in a preferred embodiment of the present invention the wastewater is subjected to a UV-dosage within the range of 2000-3000 joules/liter.

After the exposure to the UVC light source the grey water is transported to the ordinary sewage system.

Fig. 3 is an image of a string of DNA before and after being exposed to UVC light. The DNA chain exposed to the UVC light will form Thymine Dimers. This causes a genetic mutation of the genes of the microorganisms, which kills them and scrambles the genes that make them resistant to antibiotics.

A further result of exposing the grey water to the UVC light source according to the solution presented in the present invention is that the antibiotics themselves present in the grey water are destroyed.

4a shows two filtering units each fitted with an Archimedes screw for transporting the filtered particles and settled sediments into separate containers to be transported to incineration. In this solution the size of the filtering mesh in the tumblers can be from coarser to finer to be able to better filter the wastewater.

The tumbler has a large opening in one end through which the wastewater flows into. As the tumbler rotates and the water flows through the side of the tumbler, the water is filtered. The side of the tumbler is comprised of a mesh screen. The tumbler with the mesh screen and the Archimedes screw is called the filtering unit. The filtering unit filters out particles over a predetermined size.

The filtered particles are transported out of the top of the tumbler via an Archimedes screw and into a collecting bin.

In a setup like the one in this image the first predetermined size might be 1 mm and the second predetermined size might be 0.5 mm.

4b is an illustration of a solution wherein there is only one filtering unit in the form of a tumbler fitted with an Archimedes screw for transporting the filtered particles and settled sediments into separate containers to be transported to incineration.

The tumbler has a large opening in one end through which the wastewater flows into. As the tumbler rotates and the water flows through the side of the tumbler, the water is filtered. The side of the tumbler is comprised of a mesh screen. The tumbler with the mesh screen and the Archimedes screw is called the filtering unit. The filtering unit filters out particles over a predetermined filtering size of about 0.5-1 mm

4c is a picture of a similar solution to the one presented in 4b.

The pipes in which the wastewater is exposed to UV light are fitted with multiple rings along the entire length of the inside of the pipe. These rings help to create turbulent flow of the wastewater. With the rings the flow of the wastewater has a Reynolds number of around 4000. This allow the emitted light from the lamps inside the pipes to be utilized at a much higher efficiency than if the flow of wastewater in the pipe was laminar an only relying on transmittance efficiency.

Depending on the degree of contamination of the wastewater under treatment one can run the liquid through a number of these pipes connected in series. In this way the induced UV can be set at 1000-4000 joule pr liter. The treatment has proven to reduce unwanted antibiotics, bacteria, and virus in hospital sewage at a rate of 4-5 log.

Claims

1. System for treating water comprising a filtering unit through which the water flows through for filtering out particles over a certain size, an ozone chambre for ozonating the water and a treatment chambre with at least one UV light source exposing the filtered water to UV light, c h a r a c t e r i z e d i n that, the treatment chamber has a plurality of UV light sources placed parallel to each other and spaced apart at regular intervals, the UV light sources is placed inside cylindrical tubes inside the treatment chambre through which the water flows through, the shape of the UV light source is an elongated lightbulb that emits light with a wavelength range of 100-280 nm, the water is sent in a turbulent flow around the UV light sources and the turbulent flow is created by at least one inlet nozzle.

2. System according to claim 1 wherein the light sources can be placed inside pipes in the treatment chambre allowing the wastewater to flow inside the pipes and around the light sources.

3. System according to claim 1 wherein several pipes with light sources can be placed in series to increase the effect of the treatment.

4. System according to any of the claims 1-3 wherein the pipes are fitted with rings along the entire length of the inside of the pipe to create a turbulent flow.

5. System according to any of the preceding claims wherein the filtering unit can be in the form of a mesh screen.

6. System according to any of the previous claims wherein the filtering unit can be in the form of a tumbler with a mesh screen that filters the water and the filtered - out material is transported to a dumping area using an Archimedes screw.

7. System according to any of the previous claims wherein the filtering unit can be in the form of a settling tank.

8. System according to any of the previous claims wherein the water is subjected to a UV-dosage within the range of 500-5000 joules/liter.

9. System according to any of the previous claims wherein the water is subjected to a UV-dosage within the preferred range of 2000-3000 joules/liter.

10. System according to claim 1 wherein the turbulent flow is caused by pressurized movement through a cylindrical reactor with an annulated or a spiral internal geometry, forcing a disturbance in the flow of the wastewater

11. System according to claim 10 wherein the pressure is within the range of 5-10 bar.

12. System according to claims 10 or 11 wherein the movement of the water is within the range of 0.5m/s-3 m/s.

13. System according to any of the claims 10 to 12 wherein the disturbance in the flow of the water is preferably between 7000 - 8000 Reynolds.

14. Method for treating water comprising a filtering unit through which the water flows through for filtering out particles from the water over a certain size, an ozone chambre for ozonating the water and a treatment chambre with at least one UV light source exposing the filtered water to UV light, the following steps:

• filtering out particles from the water over a certain size using a filtering unit,

• ozonating the water using an ozone chambre,

• exposing the filtered water to UV light from at least one UV light source over a certain energy level,

• sending the water in a turbulent flow around the at least one UVC light source and the turbulent flow is created by at least one inlet nozzle.

15. Method according to claim 14 wherein subjecting the water to a UV-dosage within the range of 500-5000 joules/liter.

16. Method according to any of the claims 14-15 wherein subjecting the water to a UV-dosage within the range of 2000-3000 joules/liter.