WO2000068152A1

WO2000068152A1 - Method and apparatus for fluid treatment by uv-radiation

Info

Publication number: WO2000068152A1
Application number: PCT/CA2000/000526
Authority: WO
Inventors: Milton Paul Pinel; Noel K. Douglas
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-05-05
Filing date: 2000-05-05
Publication date: 2000-11-16
Anticipated expiration: 2001-11-05
Also published as: CA2336524A1; AU4530600A

Abstract

The invention relates to a compact apparatus and method for the treatment of waste water using ultraviolet radiation. The fluid treatment device comprises: a fluid inlet (24); a fluid outlet (26); a cylindrical housing (30) extending substantially vertically between the fluid inlet and the fluid outlet; flow control means (50) connected to the fluid outlet; and cooling fins (33) means externally mounted on the cylindrical housing. To ensure a thin laminar flow of fluid along the ultraviolet radiation source, the radial distance between the exterior surface of the ultraviolet radiation source and the interior wall of the cylindrical housing is between 0 and 0.25 inches. The method of treating a fluid utilizing the fluid treatment apparatus comprises the steps of: adjusting a flow control means to accommodate a flow rate of between 1 and 3 imperial gallons per minute; directing a flow of fluid into a fluid inlet; irradiating the flow of fluid as it passes by an ultraviolet radiation source positioned in a housing; directing the fluid flow through a fluid outlet; and directing the fluid flow to the flow control means. A solenoid valve (44) mounted on the fluid inlet and connected to a delay switch stops the fluid flow into the housing for a predefined period whenever power to the ultraviolet radiation source is re-engaged following a power shutdown. Utilizing the apparatus and method of the invention, efficient decontamination of human waste for residential or small commercial applications is possible.

Description

METHOD AND APPARATUS FOR FLUID TREATMENT BY UV-RADIAΗON

BACKGROUND TO THE INVENTION Field of Invention

Water or sewage treatment typically occurs in three phases: filtration, where solids contained in the fluid are removed or reduced; disinfection, using chlorine, ultraviolet (UV) radiation or the like, where bacteria and viral agents are destroyed; and purification where the fluid is, among other things, deionized at the final treatment stage. The present invention relates to an apparatus and method used in the disinfection phase, and more particularly to a method and apparatus for the disinfection of waste water using ultraviolet radiation.

Description of the related Prior Art

The ability of ultraviolet light to kill or destroy micro-organisms in air or liquid is well known. Ultraviolet light has been successfully employed as a purifying or sterilizing technique in both domestic and industrial applications. The ability of ultraviolet light to kill harmful bacteria and viruses resident in a fluid depends primarily upon three factors: the intensity of the ultraviolet light; the fluid's exposure time to the ultraviolet light; and the light transmission quality of the fluid itself. A typical configuration an ultraviolet radiation device is a residential water purification system presently marketed by Trojan Technologies Inc. and which is sold under the trade name Aqua UV Advantage Series ™ . As depicted in Figure 1, This system comprises a cylindrical housing 10, fluid inlet and fluid outlet ports 12 , 14 , an ultraviolet tube longitudinally disposed in the cylindrical housing (not shown) and heat and ultraviolet intensity sensors 16, 18 which are fixably mounted on the cylindrical housing and which are run to a remote monitor (not shown) using cable 20. Additionally cap 22 rotatably mounted in the cylindrical housing allows for removal of the ultraviolet tube and houses electrical cord 24 connected to a power source (not shown).

The system described above is suitable for the treatment of water but is unsatisfactory for the treatment of effluent in the form of human waste. Often such effluent has very high bacteria and virus counts and is unclear. Discolouration of human waste is often results from the consumption of red meat. This is due to the fact that the human gall bladder produces yellow acid to break down the red meat and as a result the waste produced can be dark yellow in colour. As discussed above, the light transmission quality of the fluid itself will determine, in part, the effectiveness of the UV radiation treatment. In the prior art described, the distance between the exterior surface of the ultraviolet tube and the internal wall of the cylindrical housing is such, that the ultraviolet radiation will not be able to penetrate the discoloured fluid and reach bacteria or viruses near the interior wall of the cylindrical housing. Therefore effluent is able to pass through the chamber without having all of the bacteria and viruses removed.

There have been attempts in the prior art to produce thin fluid layer ultraviolet radiation system to overcome the problems associated with discoloured effluent. Use of a thin fluid layer system ensures that the UV radiation is able to completely penetrate the fluid and thereby kill all contaminants present. The thin layer of fluid may run in a direction which is parallel to the ultraviolet tube as disclosed for example in Canadian Patent 1,062,437 invented by Lewis and issued on September 18, 1979, or perpendicular to the thin fluid layer as disclosed for example in United States Patent 3,837,800 invented by Wood and issued on September 24, 1974. Although the Lewis device works satisfactorily, it is a water purification system for use in the home or cottage and is not designed to handle the bacteria and virus counts associated with waste. The Wood patent is a waste purification apparatus, but it is designed for an industrial application requiring that the device be placed in a canal carrying the waste water to be treated.

Additional problems arise in the treatment of fluid with ultraviolet radiation. Firstly, those skilled in the art will appreciate that ultraviolet radiation has its maximum kill rate when the ultraviolet treatment area is at a temperature of about 80° to 100° F. If, as a result of the UV source operating, or the ambient air temperature, the temperature of the fluid treatment zone rises to a temperature of 140°F, than the performance of the system degrades considerably. Historically where large sewage treatment plants were involved which incorporated multiple ultraviolet tubes, the cylindrical housings were immersed in water to facilitate cooling. In smaller residential water purification systems such as the one manufactured by Trojan, a heat sensor is affixed to the cylindrical housing, and in the event that the system reaches a defined upper threshold, the system shuts down and reactivates when it reaches a defined lower threshold. For example, if no fluid was moving through the system, as is sometimes the case, the system would eventually shut down due to overheating. If the system shuts down and there are still bacteria and viruses resident in the housing a potentially dangerous situation could arise. If the system reactivates as a a result of new fluid entering and cooling the housing, some bacteria and viruses may be swept through the housing without having been treated, resulting in contaminated output.

A second related problem arises when the system does not incorporate a flow control mechanism. If the effluent is allowed to move through the cylindrical housing at too great a flow rate, than the bacteria and viruses carried in the effluent will not be sufficiently irradiated.

Particularly where a gravity based system is used in support of a small sewage treatment system, the flow rate through the cylindrical housing can vary greatly, depending on the usage of the system ie. the number of toilets sending waste into the system for treatment

SUMMARY OF THE INVENTION

The present invention serves to overcome the deficiencies of the prior art by providing a compact human waste disinfection system which incorporates thin fluid layer technology, an integrated cooling mechanism, effluent flow control and means to ensure that no bacteria or viruses are able to escape for the from the fluid treatment zone.

In accordance one embodiment of the invention a fluid treatment apparatus comprises: a fluid inlet; a fluid outlet; at least one bio-reactor extending substantially vertically between the fluid inlet and the fluid outlet; flow control means connected to the fluid outlet; cooling means externally mounted on the bio-reactor; wherein the at least one bio-reactor comprises a housing and an ultraviolet radiation source extending longitudinally along the axis of the housing; and wherein the radial distance between the exterior surface of the ultraviolet radiation source and the interior wall of the cylindrical housing is between 0 and 0.25 inches.

The apparatus further includes: a solenoid valve mounted to the fluid inlet and a delay switch electrically connected to the solenoid valve; monitoring means fixably mounted to the housing comprising an ultraviolet radiation probe and a temperature sensor, both of which are connected to a power/control module; a "P" trap connected to the flow control means; and mounting brackets attached to the housing.

Preferably, the housing is stainless steel. More preferably, the housing is a cylinder with upper and lower ends, the lower end closed and the upper end open. Even more preferably, the fluid is human waste. Conveniently, the upper end of the cylindrical housing is internally threaded for reception of a cap seal electrically connected to the power/control module, and the lower end of the cylindrical housing includes a coil spring extending vertically along the axis of the cylindrical housing, both the cap seal and the coil spring being in contact with the ultraviolet radiation source. More conveniently, the cooling means comprises a plurality of metal fins extending radially outward from the cylindrical housing.

- J In accordance with a method of treating a fluid in a fluid treatment apparatus comprising a fluid inlet, a fluid outlet, a housing extending substantially vertically between the fluid inlet and the fluid outlet, an ultraviolet radiation source extending longitudinally along the axis of the housing, flow control means connected to the fluid outlet and cooling means externally mounted on the housing, the method comprises the steps of: adjusting the flow control means to accommodate a flow rate of between 1 and 3 imperial gallons per minute; directing a flow of fluid into the fluid inlet; irradiating the flow of fluid as it passes by the ultraviolet radiation source; directing the fluid flow to the fluid outlet; and directing the fluid flow through a "P" trap connected to the flow control means; wherein a solenoid valve mounted on the fluid inlet and connected to a delay switch stops the fluid flow into the housing for a defined period whenever power to the ultraviolet radiation source is re-engaged following a power shutdown.

The method further includes: monitoring means fixably mounted to the housing comprising an ultraviolet radiation probe and a temperature sensor, the monitoring means connected to a power/control module; and mounting brackets attached to the housing.

The method further includes the step of turning off the ultraviolet radiation source when an event comprising the radiation level dropping to a predefined threshold or the temperature reaching a maximum predefined threshold occurs.

Preferably, the housing is stainless steel. More preferably, the housing is a cylinder with upper and lower ends, the lower end closed and the upper end open. Even more preferably, the fluid is human waste. Conveniently, the upper end of the cylindrical housing is internally threaded for reception of a cap seal electrically connected to the power/control module and the lower end of the cylindrical housing includes a coil spring extending vertically along the axis of the cylindrical housing, both the cap seal and the coil spring being in contact with the ultraviolet radiation source. More conveniently, the cooling means comprises a plurality of metal fins extending radially outward from the cylindrical housing.

The advantages of the present invention are numerous. By utilizing a very thin fluid layer around the ultraviolet tube, human waste can be treated in a manner that reduces the bacteria and virus count to an acceptable level (250 or less). Further, the integration of cooling means onto the external surface of the cylindrical housing ensures that the system will remain in a radiating state to ensure that all bacteria and viruses entering the treatment zone are killed. Additionally, the incorporation of a flow control device at the fluid outlet port further ensures that all contaminants n t e e uent are erase . F na y, t e e ay sw tc cooperat ng w t t e so eno valve controlling effluent intake, is an important safety feature which is used in the event of hydro failure. Upon UV restart, no effluent is allowed to flow until the cylindrical housing is thoroughly irradiated. Therefore, the chance of bacteria and viruses being swept through the irradiation zone untreated is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention and further advantages of the system will be obtained by reading the description of the invention below, with reference to the following drawings, in which:

Figure 1 is a side view of a prior art system

Figure 2 is a partial cross-sectional view of a system in accordance with the present invention.

Figure 3 is a cross-sectional view of a system in accordance with the present invention taken about the line A - A of Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to Figure 2, a preferred embodiment of the present invention is depicted. The basic components of the ultraviolet radiation apparatus include fluid inlet 24, fluid outlet 26, and a bio- reactor, shown generally as 28 which comprises cylindrical housing 30 and ultraviolet radiation source 32 seated between spring 31 and cap seal 34 which is rotatably mounted in cylindrical housing 30. Cylindrical housing 30 is mounted vertically onto a supporting wall using mounting brackets 36, 38. As will be understood by those skilled in the art, cylindrical housing 30 is constructed of stainless steel or some other suitable material resistant to rust and ultraviolet radiation. Integral to cylindrical housing 30 are cooling fins 33.

Also affixed to mounting bracket 36 are delay switch 40 and power/control module 42, with delay switch 40 being electrically connected to power/control module 42. Mounted on fluid inlet 24 is solenoid valve 44 which is electrically connected to delay switch 40. Mounted on cylindrical housing 32 is ultraviolet light probe 46, also electrically connected to delay switch 40, along with temperature sensor 48 mounted on cooling fins 33. Power/control module 42 is also electrically connected to cap seal 34. Extending from fluid outlet 26 is flow control valve 50, eyon w c s pos t one samp e va ve . na y, trap w t ntegra c ean out p ug

56 is joined to fluid outlet 26 beyond sample valve 52.

Figure 3 offers a cross-section of the bio-reactor 28 with cooling fins 33 affixed to cylindrical housing 30. As will be understood by those skilled in the art a protective quartz sheath 58 may surround the ultraviolet tube, thereby leaving an air space between the sheath and the tube. The quartz sheath 58 serves to insulate the tube from the water flowing around it and to assist in maintaining the ideal temperature in the fluid treatment zone. The radial distance between the exterior of quartz sheath 58 and the interior wall of cylindrical housing 30 (labelled generally as C) is about 1/4 inch, with the overall internal diameter of the cylindrical housing being approximately 1.5 inches.

In operation, the ultraviolet radiation apparatus functions using the force of gravity. If installed in a sea vessel or residential home for example, effluent generated from toilets, showers and the like would pass through some form of filtration system (not shown) to remove and or reduce any large particles present, so that the output of the filtration process only includes particles of about 10 microns or less in size. After filtration, the effluent would be directed to fluid inlet 24, which is typically about 3/4 of an inch in diameter. The effluent would then fall vertically through the fluid treatment zone or bio-reactor 28. Because of the restrictive 1/4 inch gap between quartz sheath 58 and cylindrical housing 30, the effluent is forced to flow in a vary thin layer. This ensures that even in the event that the effluent is somewhat discoloured, the ultraviolet radiation source 32 will be effective in eliminating all bacteria and viruses present. Typically the bio- reactor 28 is approximately 36 inches in length with the ultraviolet radiation source 32 having the following electrical/ performance characteristics: 120V/60Hz/65W and emitting ultraviolet radiation in the range of 2000 to 2700 Angstroms. However, as those skilled in the art will appreciate, the length of the fluid treatment zone required is primarily a function of the gap C, the flow rate of the effluent and the electrical/performance characteristics of the ultraviolet radiation source. Therefore, given for the parameters outlined above, flow control 50 is normally set to allow a flow rate of 1 to 3 imperial gallons per minute. Higher flow rates are possible for example if the treatment zone is lengthened or the power output of the ultraviolet radiation source increased.

If removal or replacement of radiation source 32 is required, cap seal 34 is simply unscrewed and radiation source 32 pulled vertically upward. In this way the spillage of effluent is minimized. Additionally to ensure that the bio-reactor 28 has eliminated all bacteria and viruses present, a sample of the fluid exiting the chamber may be taken and tested using sample valve 52. Further, ultraviolet light probe 46 is used to monitor the output of ultraviolet radiation source 32. If the output of the ultraviolet radiation source 32 falls below a defined threshold, than power/control module 42 will cause it to be shut down and solenoid valve 44 to close. Similarly, if the temperature registered by temperature sensor 48 rises above a defined threshold, power/control module 42 will cause ultraviolet radiation source 32 to shut down and solenoid 44 to close. Ideally the operating temperature of bio-reactor 28 is around 80° to 100° Fahrenheit, so that the programmed threshold would be slightly above this range. In the event that there is a power failure, power/control module 42 will also cause solenoid valve 44 to close. To ensure that all bacteria and viruses present in reactor 28 are eliminated prior to effluent flow commencing, delay switch 40 stops the flow of effluent for a defined number of seconds while ultraviolet radiation source 32 is illuminated and kills all the resident bacteria and viruses.

Power/control module 42 also performs an additional function. It is used to monitor the number of hours the ultraviolet radiation source has been in use and warn the user that replacement is required. Typically an ultraviolet radiation source in the form of an ultraviolet bulb will be effective for approximately 8000 to 9000 hours. Finally, "P" trap 56 is filled with fluid to provide an air seal between the bio-reactor 28 and the parts of the system located downstream, to ensure that no reverse migration is possible in the unlikely event that there are bacteria of viruses present downstream.

In the case of a sea vessel, once the effluent has been treated in the bio-reactor 28, it would flow into a transfer tank and from there be pumped overboard. In the case of a residential home, the fluid outputted from the bio-reactor 28 could be stored in a holding tank and used to water the lawn or similar activities.

A person understanding this invention may now conceive of alternative applications and embodiments or variations of the above. In particular, the use of the described apparatus for the purification of milk is also possible. All of those embodiment s and methods of operation which fall within the scope of the claims appended hereto are considered to be part of the invention.

Claims

The embodiments o t e nvent on n w c an exc us ve property or p vi ege s c a me are defined as follows:

1. A fluid treatment device comprising:

(a) a fluid inlet;

(b) a fluid outlet;

(c) at least one bio-reactor extending substantially vertically between the fluid inlet and the fluid outlet;

(d) flow control means connected to the fluid outlet;

(e) cooling means externally mounted on the bio-reactor;

wherein the at least one bio-reactor comprises a housing and an ultraviolet radiation source extending longitudinally along the axis of the housing;

and wherein the radial distance between the exterior surface of the ultraviolet radiation source and the interior wall of the cylindrical housing is between 0 and 0.25 inches.

2. The device of claim 1 further including a solenoid valve mounted to the fluid inlet and a delay switch electrically connected to the solenoid valve.

3. The device of claim 2 further including monitoring means fixably mounted to the housing;

4. The device of claim 3 wherein the monitoring means includes an ultraviolet radiation probe and a temperature sensor connected to a power/control module.

5. The device of claim 4 further including a "P" trap connected to the flow control means.

6. The device of claim 5 wherein the housing is stainless steel.

7. The device of claim 6 wherein the housing is a cylinder with upper and lower ends, the lower end closed and the upper end open.

8. The device of claim 7 wherein the cooling means comprises a plurality of metal fins extending radially outward from the cylindrical housing.

9. The device of claim 8 wherein the upper end of the cylindrical housing is internally threaded for reception of a cap seal electrically connected to the power/control module and the lower end of the cylindrical housing includes a coil spring extending vertically along the axis of the cylindrical housing, both the cap seal and the coil spring being in contact with the ultraviolet radiation source.

10. The device of claim 9 further including mounting brackets positioned on the upper and lower ends of the cylindrical housing.

11. The device of claim 10 wherein the fluid is human waste or effluent.

12. A method of treating a fluid in a fluid treatment apparatus comprising a fluid inlet, a fluid outlet, a housing extending substantially vertically between the fluid inlet and the fluid outlet, an ultraviolet radiation source extending longitudinally along the axis of the housing, flow control means connected to the fluid outlet and cooling means externally mounted on the housing, the method comprising the steps of:

(a) adjusting the flow control means to accommodate a flow rate of between 1 and 3 imperial gallons per minute;

(b) directing a flow of fluid into the fluid inlet;

(c) irradiating the flow of fluid as it passes by the ultraviolet radiation source;

(d) directing the fluid flow to through the fluid outlet; and

(e) directing the fluid flow through a "P" trap connected to said flow control means,

wherein a solenoid valve mounted on the fluid inlet and connected to a delay switch stops the fluid flow into the housing for a defined period whenever power to the ultraviolet radiation source is re-engaged following a power shutdown.

13. The method of claim 12 further including monitoring means fixably mounted to the housing;

14. The method of claim 13 wherein the monitoring means includes an ultraviolet radiation probe and a temperature sensor connected to a power/control module.

15. The method of claim 14 further including the step of turning off the ultraviolet radiation source when an event comprising the radiation level dropping to a predefined threshold or the temperature reaching a maximum predefined threshold occurs..

16. The device of claim 15 wherein the housing is a stainless steel cylinder with upper and lower ends, the lower end closed and the upper end open.

17. The device of claim 18 wherein the cooling means comprises a plurality of metal fins extending radially outward from the cylindrical housing.

18. The device of claim 17 wherein the upper end of the cylindrical housing is internally threaded for reception of a cap seal electrically connected to the power/control module and the lower end of the cylindrical housing includes a coil spring extending vertically along the axis of the cylindrical housing, both the cap seal and the coil spring being in contact with the ultraviolet radiation source.

19. The device of claim 18 further including mounting brackets positioned on the upper and lower ends of the cylindrical housing.

20. The device of claim 21 wherein the fluid is human waste or effluent.