Since the 19th Century discovery of the cause of cholera epidemics in London and their prevention through treatment of sewage and other effluent to remove and/or kill organisms within the effluent, many advances have been made in the treatment of organically polluted effluent. Early in the development of water treatment systems, chlorine and other halides were found to have deleterious effects on water born organisms, and chlorine compounds are now commonly used to reduce the number of living organisms in water supplies to reasonably safe levels.
It has also been determined that photonic absorption, such as is possible with high levels of radiation at preferentially absorbed frequencies, can cause total photodynamic inactivation of several bacteriophages. (See R. Hall as cited in General Electric Lamp bulletin LD-14; and M. Luckiesh, xe2x80x9cGermicidal Eythermal Energy Researchxe2x80x9d from D. Van Nostrand Co). When a non-fluorescing organism absorbs a photon, the energy is usually converted into vibrational energy (heat) that raises the internal temperature of the organism. Viral organisms are extremely sensitive to such energy. They are so small that the absorption of very few photons causes their internal temperature to rise to levels that are dangerous to their continued existence. In fact, this form of heat energy within viral organisms, causes viral inactivation when the temperatures there within exceed 100xc2x0 C.
Photobiologists have discovered absorption curves for various biological parts. For example, proteins normally have peak absorption when exposed to radiated ultraviolet (UV) energy at wavelengths of 300 nanometers (nm) to 280 nm, and ribonucleic acid (RNA) has an absorption peak to radiant wavelengths from 265 nm to 245 nm, with an absolute peak at 253.7 nm. The peak absorption for virions occurs at about 260 nm. 184.9 nm energy is the peak energy used for the breakdown of the hydrogen bond that links the DNA chain and phosphorous bond that links the RNA chain. In addition, application of 184.9 nm UV causes free oxygen molecules in the substance under treatment to add an oxygen atom to form ozone, a proven virion deactivator.
Therefore, sterilizers have been constructed that expose a fluid stream to ultraviolet radiation in the 300 nm to 180 nm wavelength range at an applied power of the 30 Kergs per mm2 or more required to disassociate the deoxyribonucleic acid (DNA) and RNA of viral organisms.
Although with prior art UV sterilization devices, it has been possible to provide UV energy in the correct range of wavelengths and at lethal power levels, such UV devices have had numerous disadvantageous features. First, many have poorly designed flow channels that allow organisms to flow there through without receiving a lethal dose of ultraviolet radiation. Most apply the requisite amount of UV too slowly, thereby allowing viral organisms to produce pigment like molecules that dilute the effect of UV light so that what should be a lethal level, can be withstood. Studies have shown that certain types of viral organisms can produce the UV blocking molecules in as little as ten milliseconds. This means that to apply a lethal dose of UV energy to those virions capable of protecting themselves from UV light, enormous concentrations of UV energy must be provided, since a lethal or at least a debilitating amount of UV energy must be applied and absorbed by every exposed viral organism in less than the first ten milliseconds that the viral organism is exposed. Commercially available intense UV sources used in the prior art devices tend to be narrow frequency devices that are unable to produce lethal intensity at all the peak absorption wavelengths of organisms. The broadband UV energy producing devices that are available produce UV light at relatively low power levels. Examples of these latter sources are UV fluorescent tubes, which produce UV at such low levels that literally hundreds of thousands of lamps are required to treat the effluent in a normal commercial sewage treatment plant.
Over time, when selective kills are attempted, either by chemical means, or inadequate levels or improper wavelengths of radiant energy, microorganisms adapt and become resistant to common killing schemes. Hence, in the case of chlorine, there is evidence that sewer and water supply microorganisms have evolved to tolerate high levels of chlorine. In fact, some now even are able to metabolize chlorine. Not withstanding a reduction in efficacy, chemicals like chlorine build up in an environment, if not poisoning it, changing it in undesirable ways.
Therefore, there has been a need to provide a non-chemical microorganism sterilization process and system for performing the process that allows less than one viable microorganism (including bacteria, virions, fungi, and bacterial spores) to pass therethrough, which can be manufactured relatively economically, and can operate in highly polluted, organic waste water environments as well as being scalable to portable potable water supplies at one extreme and to large city sewage treatment systems at the other extreme.
The present water treatment system, whether it be large enough for the treatment of an entire city""s sewer outflow or just large enough to produce potable water for a military platoon size water supply, includes a particulate filter or settling and floating device to remove relatively large solids, greases and other compounds from the input effluent stream that could dirty and clog downstream components of the system. If potable water is to be the final result of the system, chemical filters are included downstream of the solids filters to remove hazardous inorganic materials such as heavy metals from the input stream. Even after passing through fine filters, an effluent stream is likely to have so many bacteria, bacterial spores, fungi and virions therein, that such effluent can be characterized as an organic soup.
The present invention includes a pulse type pump that moves a predetermined amount of this organic soup into a stunning chamber. In the stunning chamber, a relatively high electric potential is applied across bacterial organisms and spores to fracture cell membranes and slow the natural processes of any viral organisms present.
A typical stunning chamber for a sewer treatment plant includes a plurality of interleaved plates of opposite electrical potential that are spaced far enough apart that microorganisms or small organic or inorganic particles do not wedge there between, clogging the chamber, yet close enough to apply substantial electric potential from end to end across bacteria therebetween. If proper levels of electrical potential are applied in the stunning chamber, no celled organisms emerge therefrom with their cell walls intact. Even if the electric potential is insufficient to cause some of the bacteria to lose structural integrity, it can still be large enough to disorient both the viral organisms living therein and virions present in the fluid so that they are unable to initiate their UV protection mechanisms discussed above.
Intense UV light can be applied immediately after stunning to destroy any viral organisms within or outside the bacteria and the spores through photon absorption and thermal destruction. However, in the present water treatment system, the stunned organisms are usually passed first through a cavitation chamber where they are physically agitated for further disorientation and membrane rupture before exposure to UV radiation. A typical cavitation chamber is one having piezo-electric transducers positioned with respect to the flow to assure that all microorganisms passing therethrough are exposed to high levels of acoustic energy (usually greater than 140 dB at 500 to 1000 Hz).
Whether acoustically tortured or not, the microorganisms in the flow are then pulse flowed to one or more molecularly implanted simulated emitter (MISE) chambers usually provided in tubular form to apply high levels of radiant UV energy to the stream without warning to microorganisms in the pulsed stream. Although in large systems, initial exposure to the UV energy may not be sufficient to kill all viral organisms, it at least further inhibits the viral organisms"" ability to mount a defense to lethal doses applied over time thereafter. This xe2x80x9csurprisexe2x80x9d application is accomplished by sizing the flow passages from the pulse pump to the MISE tube and the flow passages within the stunning and cavitation chambers large enough that pulse flow is maintained with little pressure drop. The outlet of the MISE entry tube usually takes the form of a restrictive orifice, Therefor the flow produced by the pulse pump moves pulse after pulse of fluid into the MISE tube. The pump is coordinated with MISE tube UV exciter control electronics so the MISE entry tube is dark as a fresh volume of effluent is pumped therein. Once the flow has substantially slowed, the UV emitter means of the MISE tube are pulsed at high power levels. Since the viral organisms entering the MISE tube have been stunned and tortured until they are unable to use their UV protection mechanisms, in the present system it is not mandatory as otherwise would be the case, that the viral organisms are xe2x80x9csurprisedxe2x80x9d by their exposure to UV energy.
Generally, the MISE tubes are elongated cylinders. Large industrial MISE tubes for sewer treatment have intense UV sources at each end while MISE tubes for portable potable water supplies can include a concentric UV emitter, such as a fluorescent lamp, extending from end to end down the middle thereof. The MISE tubes are designed to expose any microorganism therein to intense UV radiation. One method to assure complete exposure this is to coat the inner surface of the MISE tube with material that is highly reflective of UV radiation. Magnesium oxide is preferred because it is easy and economical to apply and is highly reflective of the UV energy. The inner surface is then coated with a UV transparent, protective coating for a long life. Since UV sources seldom produce all of the desired wavelengths of enough intensity, UV fluorescent material that absorb wavelengths in over abundance or those having little affectivity and then re-radiate UV at needed wavelengths otherwise weakly present, may be included in the protective coating. Having the outer wall of the tube actually radiate as well as reflect further assures that within the MISE tube, there is no shadow area where microorganisms can hide.
Usually, the outlet of the MISE tube is the minimal flow area for the system so that upstream of the MISE tube outlet, effluent flow is in pressure pulses and downstream it is relatively constant flow. The area around the outlet may be coated with compounds that fluoresce at wavelengths that repel microorganisms, since experiments have shown that a small fractional percent of slightly viable, large mobile virion, were attempting to escape from the outlet.
When the area of the MISE tube adjacent the outlet is Gamma soured and bright blue fluoresced, such virion appear to expend enough energy in moving away from the outlet to become deactivated. Therefore, the natural tendencies of such virion to attempt to avoid UV exposure is used against them and the possibility of outlet escape is eliminated. Suitable electronics coordinate the action of the pump, the stunning chamber, the cavitation chamber, and the MISE tube to efficiently use electrical energy supplied thereto to keep operating costs for electrical power to a minimum. The electronics can be programmed to operate independently or can be controlled through the use of operating personnel control inputs and a display.
Tests of small scale versions of the present system show the synergistic effect of both the MISE tube and stunning chamber because if either is not operating, live organisms emerge whereas if both are operating, less than one live organism ever emerges from the MISE tube. However, the effluent flowing out of the MISE tube may be what can be characterized as a primordial life mixture, full of organic molecules and fragments in such concentrations that it is conceivable they could recombine into viable organisms.
In the case of a small scale water supply system, the output is likely to have relatively few organic molecules therein because normally, the input chosen is not highly concentrated raw sewage. Therefore, the small water supply system output may be just passed to a dark solid state chiller so that little energy is available for recombination of the organic molecules and fragments. Although the output water of the chiller is safe to drink, the organic fragments therein tend to preferentially pass yellow optical frequencies, which give the water an unpalatable appearance. Therefore, the output of the chiller is passed through a carbon filter to remove the organic molecules and fragments so that crystal clear drinking water is delivered.
In a sewage treatment system, multiple settling and float tanks, particulate filters, pumps, stunning chambers, cavitation chambers and MISE tubes may be interconnected by suitable valves so that any component can be taken off line for repair or cleaning, should such be required. The output flow of the MISE tubes without further treatment is suitable as the exhaust effluent of a sewage plant. However, since in most instances sewage plants have their output flow piped a considerable distance before being dumped in a diluting water volume (such as a lake, large river or ocean) a flow channel is provided with a covering that either prevents recombination energy from reaching the organic molecules and fragments, or includes a solar filter that allows only damaging radiation to pass into the flow channel to assure no recombination can occur before dilution where the physical distance between the organic molecules and fragments becomes so large that recombination can not occur.
Therefore, it is a principal object of the present invention to provide a non-chemical fluid treatment system for sterilizing a waste water flow.
Another object is to provide a process to treat waste water, which allows less than one organism to pass viably therethrough, and therefore presents no danger of assisting microorganisms to evolve that are resistant to the system.
Another object is to provide an energy efficient microorganism sterilizing method whose operating principles can be applied to small scale potable water supply systems or large sewage treatment plants.
Another object is to provide a UV microorganism sterilizing device having pre-treatment means that overcome viral organism""s responsive defenses to UV radiation.
Another object is to provide a MISE tube, which produces high levels of broadband UV radiation suitable for disrupting the nucleic acids of microorganisms and designed so that any organism passing therethrough is exposed to a lethal dose of UV radiation.
Another object is to provide MISE tubes that are long lasting, easily manufactured, and relatively economical to manufacture and operate in a wide variety of environments.
These and other objects and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed specification together with accompanying drawings wherein: