Liquid purification or separation – Processes – Utilizing electrical or wave energy directly applied to...
Reexamination Certificate
2001-09-04
2004-08-10
Hoey, Betsey Morrison (Department: 1724)
Liquid purification or separation
Processes
Utilizing electrical or wave energy directly applied to...
C210S759000, C210S760000, C210S192000, C210S194000, C210S205000, C210S252000, C210S909000, C210S916000
Reexamination Certificate
active
06773609
ABSTRACT:
TECHNICAL FIELD
This invention relates to an advanced water treatment technique for oxidative destruction of harmful substances typified by environmental hormones, such as dioxins and PCB, by using the strong oxidation power of ozone.
BACKGROUND OF THE INVENTION
Today, we face the growing problem of how to deal with harmful substances, such as environmental hormones, on the earth. Dioxins are typical examples of harmful substances. It is reported that dioxins generated in Japan (those generated by incinerator plants of its municipalities alone) amount to 2,800 grams (fiscal 1998). To cope with this problem, controls of incinerator plants, sources of generation of dioxins, are being made stricter so as to limit the amounts of dioxins generated thereat.
However, restrictions alone on the generation of dioxins is not sufficient for reduction of the amount of dioxins present in the environment, because once they are generated, they circulate through the environment without being destroyed. Therefore, unless dioxins circulating in the environment are destroyed to thereby end their circulation while the amount of generation thereof is restricted, the whole amount of dioxins in nature cannot be decreased.
For instance, dioxins circulate in the environment as follows: Dioxins once released from an incinerator plant contaminate food, such as agricultural, livestock and fishery products, enter human bodies via the food, and then are discharged as wastes from human bodies into the environment. Those wastes containing harmful substances, such as dioxins, are collected in human wastes treatment facilities and public sewage works, or put together in single or joint private sewage systems all over the country and flow therefrom into rivers and then into the sea.
As described above, dioxins collected in human wastes treatment facilities or public sewage works via human wastes are released into the environment without being decomposed. Harmful substances released into the environment repeatedly return to human bodies via fishery products and the like while being increased in concentration. As described hereinabove, unless the vicious circle in the circulation of dioxins is broken anywhere, adverse influences of dioxins present in the environment on human bodies cannot be reduced even if only the amount of generation of dioxins is restricted.
The ozone treatment and the hydrogen peroxide solution treatment are known as techniques of decomposing harmful substances present in water to be treated. According to these treatments, it is true that harmful substances were subjected to oxidative destruction to some purpose, but almost all of these techniques only mix ozone and hydrogen peroxide solution with water to be treated, or simply agitate the resulting mixture. Therefore, it cannot be necessarily said that they are capable of fully achieving the effects of destroying harmful substances. Even now, harmful substances, including dioxins, continue to increase in water systems in the environment, and hence the advent of a new advanced water treatment technique has been desired which promises more excellent treatment effects.
DISCLOSURE OF THE INVENTION
The present invention has been made in order to meet the above-described demand. That is, an object of the present invention is to provide an advanced water treatment technique that does not simply make use of ozone, differently from the conventional water treatment technique, but is based on an ozone treatment which is capable of braking a vicious circle of harmful substances, such as dioxins, through wastes discharged from human bodies, by providing more advanced treatment effects.
To attain the above object, the advanced water treatment process according to the present invention is based on an essential treatment process for bringing minute bubbles of ozone having an average particle diameter (bubble diameter) of e.g. 0.5 to 3 &mgr;m into contact with water to be treated, which contains harmful substances, such as dioxins and PCB, thereby carrying out the ozone treatment for oxidative destruction of the harmful substances contained in the water. In a more concrete form, an advanced water treatment system of the present invention is characterized by comprising an ozone treatment device for bringing minute bubbles of ozone having an average particle diameter (bubble diameter) of e.g. 0.5 to 3 &mgr;m into contact with the water to be treated, in a retentive manner, thereby carrying out oxidative destruction of the harmful substances.
According to this advanced water treatment process and system, ozone is not simply supplied to the water to be treated but minute bubbles of ozone are supplied to the water to be treated. More specifically, each minute bubble of ozone has a very small buoyant force, and hence ozone can be caused to stay within the water for a much longer time period. Further, areas of ozone brought into contact with the water can be made by far the larger. As a result, differently from the conventional water treatment process in which aeration is simply carried out with ozone, the efficiency of oxidation of harmful substances dissolved in the water can be dramatically improved.
The “water to be treated” for treatment by the advanced water treatment process and system of the present invention includes water at high pollution levels, such as waste water containing sludge and soil, human excreta, sewage water containing excreta of domestic animals, household waste water, clinical waste water, papermaking waste water, and industrial liquid waste, and water at low pollution levels, such as water in rivers or lakes, water used in bathhouses, swimming pools, and the like. In short, since the treatment is intended for decomposing harmful substance, so long as the water to be treated contains harmful substances, the kind of a pollution source does not matter.
Further, the harmful substances which can be decomposed include dioxins, PCB, and other environmental hormones. It goes without saying that the present process and system is capable of sterilizing infective disease such as
Escherichia coli
, salmonella, and mad cow disease.
Further, the advanced water treatment system may be of a fixed type, or an in-vehicle mobile type, but is characterized by the capability of continuous treatment.
As described hereinabove, the ozone in the form of minute bubbles has a very small buoyant force and stays within the water for a very long time period. Therefore, there is a difficulty that if only the minute bubbles of ozone are simply supplied to the ozone treatment tank, it takes much time for the ozone to be uniformly diffused throughout the water within the tank, and hence the high oxidative destruction power of the ozone realized in the form of minute bubbles is not fully made use of. Therefore, in the water treatment process of the present invention, as one method of evenly diffusing the minute bubbles of ozone, the minute bubbles are supplied to a water pipe which is provided for connecting each treatment tank arranged within a treatment system. The water is flowing violently through the water pipe, so that ozone formed into minute bubbles by “ozone supply means” comprised of an ozone generator and an ozone bubble-forming device (line mixer type, or vortex flow turbine pump type) is supplied to the water flowing through the water pipe, whereby the minute bubbles of ozone are injected into the ozone treatment tank in a gushing flow and evenly diffused throughout the inside of the tank.
Further, in another method of diffusing the minute bubbles of ozone, an ozone treatment tank for bringing the minute bubble of ozone into contact with the water to be treated in a retentive manner is provided within the treatment system, and the ozone is blown from the bottom of the tank into the water within the tank to cause a forced convection of the water. In other word, an ozone treatment tank for bringing the minute bubbles of ozone into contact with the water to be treated in a retentive manner is provided within the treatment system, and the water within the tank a
Hoey Betsey Morrison
Rader & Fishman & Grauer, PLLC
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