Industry News » IHI Corporation; \\\"Wastewater Treatment Device And Wastewater Treatment Method\\\" in Pa...

2019 APR 19 (VerticalNews) -- By a News Reporter-Staff News Editor at Chemicals & Chemistry -- A patent application by the inventors KUBOTA, Nobuhiko (Tokyo, JP); YOSHIDA, Yuka (Tokyo, JP); HUANG, Xia (Beijing, CN); LIU, Chun (Shijiazhuang, Hebei, CN); ZHANG, Jing (Beijing, CN); ZHOU, Hong Zheng (Beijing, CN); CHEN, Xiao Xuan (Beijing, CN); ZHANG, Lei (Beijing, CN), filed on October 22, 2018, was made available online on March 28, 2019, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to IHI Corporation (Tokyo, Japan).

The following quote was obtained by the news editors from the background information supplied by the inventors

       Technical Field

 "The present disclosure relates to a wastewater treatment device and a wastewater treatment method capable of performing advanced treatment of industrial wastewater utilizing ozone oxidation reaction and biological treatment using microorganisms.

Description of the Related Art

"Industrial wastewater (wastewater from chemical industry, agriculture, printing factories, dyeing plants, and the like) contains a large amount of persistent organic pollutants, and in conventional biological treatment processes, the persistent organic pollutants still remain in terminal water of biological treatment. Therefore, since the terminal water of the biological treatment of the industrial wastewater does not reach effluent standards, pollutants cannot be completely removed after introduction into municipal wastewater treatment plants, which adversely affects the municipal wastewater treatment plants. Thus, the treatment of highly polluted industrial wastewater is a global and important issue that the processing of industrial wastewater currently faces.

"Biodegradability by biological treatment of terminal drainage of industrial wastewater is extremely different depending on wastewater, and it is difficult to process the terminal wastewater using the biological treatment directly. In a practical strategy, the treatment process currently mainly used is advanced treatment including coagulation sedimentation, adsorption, and chemical oxidation.

"In order to realize the advanced wastewater treatment of the industrial wastewater, technologies of treating wastewater by combining the oxidation reaction or the photochemical reaction by ultraviolet light has been proposed. Japanese Patent Application Laid-open No. 2015-128751 (Publication Document 1 below) discloses wastewater treatment which is a combination of the biological treatment with Fenton treatment which is oxidation treatment.

"Further, ozone oxidation is a more general technology in the advanced treatment of the terminal water by the biological treatment of the industrial wastewater. However, when the ozone oxidation technology is used alone, treatment cost is frequently increased to realize the advanced treatment of the industrial wastewater. For this reason, the combination of the ozone oxidation technology with the biological treatment has been studied to reduce the treatment costs. Japanese Patent Application Laid-open No.
2015-226889 (Publication Document 2 below) discloses treatment of a liquid containing an amine-based organic compound, obtained by combining the oxidation treatment for introducing an oxidizing agent to decompose the amine-based organic compound with the biological treatment, and discloses that ozone is used as the oxidizing agent."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "However, the Fenton treatment utilized in the above-mentioned Publication Document 1 requires much time and labor because it has increased number of processes. On the other hand, since the ozone oxidation treatment utilized in the above-mentioned Publication Document 2 has low solubility of ozone in water and weak oxidizing ability of ozone, the ozone oxidation treatment has drawbacks such as a slow mass transfer rate between gas and liquid and low ozone utilization efficiency. Further, in Publication Document 2, since the ozone oxidation treatment is carried out at a pH significantly different from the subsequent biological treatment, a process of adjusting the pH at the time of shifting to the biological treatment is necessary, and the treatment cost is increased. Furthermore, even when unused ozone is discharged from wastewater, the ozone utilization efficiency is lowered.

"Further, in any of the above-described wastewater treatments, aeration is performed in order to activate treatment with aerobic microorganisms. However, the aeration of wastewater requires power, and, from the viewpoint of energy consumption, it is preferred to perform the wastewater treatment without using the aeration.

"The present disclosure has been made in view of the above-described problems, and it is an object of the present invention to provide a wastewater treatment device and a wastewater treatment method capable of preventing an inhibition of biological treatment while enjoying advantages of wastewater treatment by ozone oxidation, reducing wastewater treatment costs, and realizing excellent treatment by a simple process.

"According to an aspect of the present disclosure, a wastewater treatment device is summarized to include: an ozone generator which supplies ozone; a mixer which mixes ozone supplied from the ozone generator with wastewater and supplies ozone mixed wastewater; an ozone oxidation unit which progresses ozone oxidation in the ozone mixed wastewater while passing the ozone mixed wastewater therethrough and discharges wastewater in which the ozone has been consumed; a biological treatment unit which has microorganisms for biological treatment and performs the biological treatment on the wastewater discharged from the ozone oxidation unit using the microorganisms; and an adjusting device which adjusts the amount of ozone to be mixed with the wastewater by the mixer so that ozone in an amount that inhibits the microorganisms of the biological treatment unit does not remain in the wastewater discharged from the ozone oxidation unit.

"It is suitable that the adjusting device includes: a measuring device which measures the amount of ozone in the wastewater discharged from the ozone oxidation unit; and a regulating valve capable of regulating the amount of ozone to be mixed with the wastewater by the mixer, and the regulating valve is adjusted based on the measurement by the measuring device in such a manner that the amount of ozone in the wastewater is lower than a level at which the microorganisms are inhibited.

"The wastewater treatment device may further include: a release passage for avoiding the supply of the wastewater to the biological treatment unit when the ozone remains in the wastewater discharged from the ozone oxidation unit; and a control valve which stops the supply of the wastewater to the biological treatment unit when the amount of ozone in the wastewater is equal to or higher than the level at which the microorganisms are inhibited, based on the measurement by the measuring device. The release passage may be a return passage capable of supplying the wastewater discharged from the ozone oxidation unit to the mixer, and the wastewater may flow through the return passage when the supply of the wastewater to the biological treatment unit is stopped by the control valve.

"It is suitable that the mixer includes a bubble generator, and ozone is dispersed in the ozone mixed wastewater in a state of bubble. It is suitable that the bubble generator is a microbubble generator which generates fine bubbles having a bubble diameter of 10 to 50 .mu.m. The ozone oxidation unit may have a catalyst that promotes an ozone oxidation reaction, and the ozone oxidation unit may be configured in a multistage structure in which a plurality of catalyst beds on which the catalyst is supported are stacked in a vertical direction, and may be configured so that the ozone mixed wastewater may sequentially pass through the plurality of catalyst beds while being introduced from a bottom part of the ozone oxidation unit and rising toward a top part of the ozone oxidation unit.

"When a difference in height between the biological treatment unit and the ozone oxidation unit is provided so that a water level in the biological treatment unit is lower than that in the ozone oxidation unit, and the wastewater of the ozone oxidation unit is supplied to the biological treatment unit using a gravity action due to the difference in height, it is suitable in terms of reducing operating energy. The wastewater treatment device may further include an ozone decomposing device which decomposes ozone remaining in the wastewater discharged from the ozone oxidation unit when ozone remains in the wastewater discharged from the ozone oxidation unit.

"In addition, according to an aspect of the present disclosure, the wastewater treatment method is summarized to include: ozone generation that supplies ozone; mixing preparation for mixing the ozone supplied by the ozone generation with wastewater to supply ozone mixed wastewater; ozone oxidation treatment in which ozone oxidation is allowed to proceed in the ozone mixed wastewater, to discharge the wastewater in which the ozone has been consumed; and biological treatment in which the wastewater after the ozone oxidation treatment is biologically treated with microorganisms, wherein an amount of ozone mixed with the wastewater in the mixing preparation is adjusted so that ozone in an amount that inhibits the microorganisms of the biological treatment does not remain in the wastewater discharged from the ozone oxidation treatment.

"A ratio of ozone to be mixed with the wastewater may be adjusted according to a flow rate of the wastewater supplied to the ozone oxidation treatment and water quality of the wastewater so that an appropriate amount of ozone is mixed with the wastewater in the mixing preparation. It is suitable for application to an advanced treatment for treating industrial wastewater containing a persistent organic substance.

"According to the present disclosure, it is possible to provide a wastewater treatment device capable of improving the ozone utilization rate to enhance oxidation ability, and improving the removal efficiency of persistent chemical substances, and it is also possible to sufficiently supply the biological treatment with oxygen without performing the aeration by using dissolved oxygen generated after the ozone reaction, thereby reducing operating costs required for wastewater treatment."

The claims supplied by the inventors are:

"1. A wastewater treatment device, comprising: an ozone generator which supplies ozone; a mixer which mixes ozone supplied from the ozone generator with wastewater and supplies ozone mixed wastewater; an ozone oxidation unit which progresses ozone oxidation in the ozone mixed wastewater while passing the ozone mixed wastewater therethrough and discharges wastewater in which the ozone has been consumed; a biological treatment unit which has microorganisms for biological treatment and performs the biological treatment on the wastewater discharged from the ozone oxidation unit using the microorganisms; and an adjusting device which adjusts the amount of ozone to be mixed with the wastewater by the mixer so that ozone in an amount that inhibits the microorganisms of the biological treatment unit does not remain in the wastewater discharged from the ozone oxidation unit.

"2. The wastewater treatment device according to claim 1, wherein the adjusting device includes: a measuring device which measures the amount of ozone in the wastewater discharged from the ozone oxidation unit; and a regulating valve capable of regulating the amount of ozone to be mixed with the wastewater by the mixer, and the regulating valve is adjusted based on measurement by the measuring device in such a manner that the amount of ozone in the wastewater is lower than a level at which the microorganisms are inhibited.

"3. The wastewater treatment device according to claim 2, further comprising: a release passage for avoiding the supply of the wastewater to the biological treatment unit when the ozone remains in the wastewater discharged from the ozone oxidation unit; and a control valve which stops the supply of the wastewater to the biological treatment unit when the amount of ozone in the wastewater is equal to or higher than the level at which the microorganisms are inhibited, based on the measurement by the measuring device.

"4. The wastewater treatment device according to claim 3, wherein the release passage is a return passage capable of supplying the wastewater discharged from the ozone oxidation unit to the mixer, and the wastewater flows through the return passage when the supply of the wastewater to the biological treatment unit is stopped by the control valve.

"5. The wastewater treatment device according to claim 1, wherein the mixer includes a bubble generator, and ozone is dispersed in the ozone mixed wastewater in a state of bubbles.

"6. The wastewater treatment device according to claim 5, wherein the bubble generator is a microbubble generator which generates fine bubbles having a bubble diameter of 10 to 50 .mu.m.

"7. The wastewater treatment device according to claim 1, wherein the ozone oxidation unit has a catalyst that promotes an ozone oxidation reaction.

"8. The wastewater treatment device according to claim 7, wherein the ozone oxidation unit is configured in a multistage structure in which a plurality of catalyst beds on which the catalyst is supported are stacked in a vertical direction, and is configured so that the ozone mixed wastewater sequentially passes through the plurality of catalyst beds while being introduced from a bottom part of the ozone oxidation unit and rising toward a top part of the ozone oxidation unit.

"9. The wastewater treatment device according to claim 7, wherein a difference in height between the biological treatment unit and the ozone oxidation unit is provided so that a water level in the biological treatment unit is lower than that in the ozone oxidation unit, and the wastewater of the ozone oxidation unit is supplied to the biological treatment unit using a gravity action due to the difference in height.

"10. The wastewater treatment device according to claim 2, further comprising: an ozone decomposing device which decomposes ozone remaining in the wastewater discharged from the ozone oxidation unit when ozone remains in the wastewater discharged from the ozone oxidation unit.

"11. A wastewater treatment method, comprising: ozone generation that supplies ozone; mixing preparation for mixing the ozone supplied by the ozone generation with wastewater to supply ozone mixed wastewater; ozone oxidation treatment in which ozone oxidation is allowed to proceed in the ozone mixed wastewater, to discharge the wastewater in which the ozone has been consumed; and biological treatment in which the wastewater after the ozone oxidation treatment is biologically treated with microorganisms, wherein an amount of ozone mixed with the wastewater in the mixing preparation is adjusted so that ozone in an amount that inhibits the microorganisms of the biological treatment does not remain in the wastewater discharged from the ozone oxidation treatment.

"12. The wastewater treatment method according to claim 11, wherein a ratio of ozone to be mixed with the wastewater is adjusted according to a flow rate of the wastewater supplied to the ozone oxidation treatment and water quality of the wastewater so that an appropriate amount of ozone is mixed with the wastewater in the mixing preparation.

"13. The wastewater treatment method according to claim 11, which is applied to an advanced treatment for treating industrial wastewater containing a persistent organic substance."


Previous      Next
Return to top