Liquid purification or separation – Processes – Chemical treatment
Reexamination Certificate
2000-06-16
2001-08-14
Simmons, David A. (Department: 1724)
Liquid purification or separation
Processes
Chemical treatment
Reexamination Certificate
active
06274053
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and apparatus for treating a liquid such as water with a gas containing ozone. The apparatus may be used in the production of water suitable for human consumption from water contaminated by one or more of microorganisms, chemicals, heavy metals and minerals.
BACKGROUND OF THE INVENTION
Generally, drinking water is produced by municipalities from a lake or ground water by treating the water with ozone or chlorine. Once the water is treated, it is transported to households by pipes. Over time, contaminants may infiltrate into the pipeline. Accordingly, even though the potable drinking water is fed into the pipeline from a water treatment facility, the water may be contaminated by the time it enters a residence. Further, if there is a breakdown in equipment at the water treatment facility or a flood, contaminated water may enter the pipeline.
A variety of domestic filtration systems have been developed for use by consumers to filter water that is delivered by a tap. Such systems may use a filter made from a combination of a porous media filter and activated carbon through which water is passed. This type of system will reduce the levels of chlorine, lead, and pesticides. However, there are several disadvantages associated with this device. In particular, a filtration system will not remove microbiological contaminants from water.
Another popular system in use for the purification of contaminated water is a system which employs ultraviolet light for disinfection in series with a porous media and carbon filter. This type of system will reduce the levels of chlorine, lead, and pesticides and has some disinfection capability. One disadvantage with this system is that the ultraviolet light's disinfection efficacy is greatly diminished by turbidity or colour in the water which can cause the filter to become contaminated by microorganisms which can readily live and breed therein thereby multiplying the danger from any microorganisms which may be present. Thus, the filter of this system also suffers from the disadvantages associated with filters of filtration based systems.
Water treatment apparatus using oxidizing gases have been developed. Some of these devices operate on a batch basis. According to this process, the water is placed in a treatment container and the treatment agent (e.g. a gas), is disbursed through the water, such as via a sparger. Following the completion of the cycle, the water may then be used. One disadvantage with small scale ozone treatment systems such as for domestic applications is to produce an effective amount of ozone to kill a variety of different microbiological agents that may be present in the water.
BRIEF SUMMARY OF THE INVENTION
One method for producing ozone comprises passing a gas containing oxygen (eg. air) through a corona discharge field. The passage of the ozone through the field causes oxygen molecules to recombine to produce ozone. As the flow rate of gas through the corona discharge field increase, the amount of ozone which is produced per unit of time (eg. per minute) also increases. However, the rate of change of these two rates are not proportional. Therefore, as the flow rate of gas through the corona discharge field increases, the concentration of ozone in the gas leaving the corona discharge field decreases even though the total amount of ozone produced per unit time increases. Accordingly, a corona discharge ozone generator produces more grams of ozone per unit time at higher gas flow rates there through; however, the concentration of ozone produced by the ozone generator is lower. The higher flow rate provides more ozone per unit time and results in the rapid oxidation of many contaminants in water. However, it has been determined that the lower concentration of ozone produced by the higher flow rate is insufficient to oxidize some chemical compounds and to kill some micro-organisms.
Therefore, in accordance with the instant invention, a liquid such as water is treated under two successive steps with ozone. Pursuant to the first step, an oxygen containing gas is passed through a corona discharge generator at a relatively high flow rate to produce a gas containing ozone at a relatively low concentration and this gas is then used to treat the liquid. This step produces a greater mass of ozone per unit time than if a the gas were passed through the corona discharge generator at a lower flow rate. This results in the relatively rapid treatment of many contaminants due to the larger mass of ozone which is produced. Subsequently, an oxygen containing gas is passed through a corona discharge generator at a relatively low flow rate to produce a gas containing ozone at a relatively high concentration and this gas is then used to treat the liquid. While the liquid is treated with a lower amount ozone per unit time during the second step, the increased concentration is used to oxidize those contaminants that are not oxidized efficiently by the lower concentration of ozone that is produced in the first step.
One advantage of this method is that the total treatment time for the liquid is reduced without compromising the degree to which the liquid is treated.
In accordance with the instant invention, there is provided a method for treating a liquid with a gas containing ozone comprising the steps of passing air through an ozone generator at a first flow rate to produce air having a first concentration of ozone and introducing the air having the first concentration of ozone into the liquid; and, subsequently passing air through the ozone generator at a second flow rate to produce air having a second concentration of ozone which is higher than the first concentration of ozone and introducing the air having the second concentration of ozone into the liquid.
In one embodiment, the second flow rate is lower than the first flow rate. Preferably, the second flow rate is about 50 to 85% lower than the first flow rate. Preferably, the second concentration is at least 25% higher than the first concentration.
In another embodiment, the ozone generator is a corona discharge generator and the method further comprises providing a substantially constant current to the ozone generator.
In another embodiment, the method further comprises the step of introducing the liquid to be treated into a treatment vessel prior to introducing the gas into the liquid.
In another embodiment, the liquid is water and the method further comprises introducing the water to be treated into a treatment vessel prior to introducing the gas into the liquid whereby potable water is produced by contacting the water with the gas.
In accordance with the instant invention, there is provided a method for treating a liquid with a gas containing ozone comprising the steps of treating the liquid with a first ozone containing gas which contains ozone at a first concentration; and, subsequently treating the liquid with a second ozone containing gas which contains ozone at a second concentration which is higher than the first concentration.
In one embodiment, the first ozone containing gas is introduced at a first flow rate to the liquid and the second ozone containing gas is introduced at a second flow rate to the liquid and the second flow rate is lower than the first flow rate.
In another embodiment, the ozone is produced by passing a gas containing oxygen through a corona discharge generator and the second ozone containing gas is produced by passing gas through the ozone generator at a lower flow rate than is used to produce the first ozone containing gas.
In another embodiment, the method further comprises providing a substantially constant current to the ozone generator.
REFERENCES:
patent: 5498347 (1996-03-01), Richard
patent: 5888403 (1999-03-01), Hayashi
patent: 6068778 (2000-05-01), Steiner et al.
patent: 6074564 (2000-06-01), Foellmi
Bereskin & Parr
Fantom Technologies Inc.
Hoey Betsey Morrison
Mendes de Costa Philip C.
Simmons David A.
LandOfFree
Ozonation process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ozonation process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ozonation process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2497607