OZONE-PHOTOCATALYSIS REACTOR AND WATER TREATMENT METHOD

Abstract

An ozone-photocatalysis reactor, comprising: a shell layer (1); activated carbon layers (2) arranged in the shell layer (1); and at least one photoxidation unit arranged in the shell layer (1) and above the activated carbon layers (2). The photoxidation unit comprises a honeycomb activated carbon layer I (3), a light source layer and a honeycomb activated carbon bed layer II (4) sequentially from bottom to top. A gas inlet (7) and a water inlet (6) are formed in the shell layer below the activated carbon layers (2); a water outlet (9) and a gas outlet (10) are formed in the shell layer (1) above the photoxidation unit; and the activated carbon layers (2), at least one honeycomb activated carbon bed layer I (3) and at least one honeycomb activated carbon bed layer II (4) are loaded with a solid catalyst. The reactor uses ozone oxidation and ozone-photocatalysis sufficiently for sewage treatment, the treatment time is short, and the treatment efficiency is high.

Claims

1. An ozone-photocatalysis reactor, wherein the reactor comprises: (i) a shell layer; (ii) an activated carbon layer arranged inside the shell layer; and (iii) at least one photoxidation unit arranged inside the shell layer and above the activated carbon layer; and the photoxidation unit comprises a honeycomb activated carbon bed layer I, a light source layer and a honeycomb activated carbon bed layer II sequentially arranged from bottom to top; wherein a gas inlet and a water inlet are arranged on the shell layer below the activated carbon layer; and a water outlet and a gas outlet are arranged on the shell layer above the photoxidation unit; the activated carbon layer is loaded with a solid catalyst; and the honeycomb activated carbon bed layer I and the honeycomb activated carbon bed layer II are loaded with a solid photocatalyst.

2. The reactor according to claim 1, wherein light transmittance of the honeycomb activated carbon bed layer I and the honeycomb activated carbon bed layer II is set to satisfy a predetermined percentage.

3. The reactor according to claim 1, wherein the activated carbon layer is any one of a honeycomb activated carbon bed, honeycomb ceramic or granular activated carbon.

4. The reactor according to claim 1, wherein the light source layer is a light source capable of emitting visible light and/or ultraviolet light.

5. The reactor according to claim 1, wherein the solid photocatalyst is TiO.sub.2 and/or metal doped TiO.sub.2.

6. The reactor according to claim 1, wherein thickness of the activated carbon layer accounts for 20%-95% of the sum of the height of the activated carbon layer and the photooxidation unit.

7. The reactor according to claim 1, wherein when the activated carbon layer is a honeycomb activated carbon bed, the honeycomb activated carbon bed is arranged in a staggered manner.

8. The reactor according to claim 1, wherein a gas distributor is also arranged inside the shell layer, below the activated carbon layer, and above the gas inlet.

9. The reactor according to claim 1, wherein the reactor is disposed sequentially from bottom to top with: an activated carbon layer which is a honeycomb activated carbon bed having a square hole aperture less than or equal to 0.5 cm and loaded with a solid catalyst having a content no more than 0.5%; a honeycomb activated carbon bed layer I having a thickness of 5-20 cm, the honeycomb activated carbon bed layer I has a square hole aperture of 0.5-1 cm and is loaded with 2-10% of the solid catalyst ; an ultraviolet light source layer composed of horizontally arranged cylindrical ultraviolet light tubes covered with transparent quartz tubes, the intensity of the emitting light of the ultraviolet light tube is 10-1000 mW/cm.sup.2; a honeycomb activated carbon bed layer II having a thickness of 5-20 cm, the honeycomb activated carbon bed layer II has a square hole aperture of 0.5-1 cm and is loaded with 5-20% of the solid catalyst; the reactor is disposed with a gas inlet and a water inlet below the activated carbon layer, and a water outlet and a gas outlet are disposed above the honeycomb activated carbon bed layer II of the reactor; the distance of the honeycomb activated carbon bed layer I and the honeycomb activated carbon bed layer II from the ultraviolet light source layer is independently selected from 5-30 cm.

10. The reactor according to claim 2, wherein content of the solid catalyst loaded on the activated carbon layer, the honeycomb activated carbon bed layer I and the honeycomb activated carbon bed layer II arranged in the shell layer is increased sequentially from bottom to top.

11. The reactor according to claim 3, wherein the activated carbon layer is a water-resistant honeycomb activated carbon bed; and both of the honeycomb activated carbon bed layer I and the honeycomb activated carbon bed layer II are water-resistant honeycomb activated carbon beds.

12. The reactor according to claim 11 wherein, the honeycomb activated carbon bed has square holes.

13. The reactor according to claim 12, wherein aperture of the square hole in the honeycomb activated carbon bed of the activated carbon layer is less than or equal to 0.5 cm; and aperture of the square hole in the honeycomb activated carbon bed layer I and the honeycomb activated carbon bed layer II is independently selected from 0.5-1 cm.

14. The reactor according to claim 4, wherein the light source of the light source layer is covered with a quartz protective cover.

15. The reactor according to claim 5, wherein the metal for doping is any one or a combination of at least two selected from the group consisting of Ni, Fe, Cu, and Mn.

16. The reactor according to claim 5, wherein the solid catalyst is selected from a solid ozonation catalyst.

17. The reactor according to claim 16, wherein the solid catalyst is selected from a transition metal oxide catalyst for ozonation

18. The reactor according to claim 17, wherein the solid catalyst is selected from any one or a combination of at least two of TiO.sub.2 catalyst, CuO catalyst, MnO.sub.2 catalyst, NiO catalyst or Fe.sub.2O.sub.3 catalyst.

19. The reactor according to claim 5, wherein the content of the solid catalyst loaded on the activated carbon layer is less than or equal to 5%.

20. The reactor according to claim 5, wherein when the reactor contains only one photooxidation unit, content of the solid photocatalyst loaded on the honeycomb activated carbon bed layer I is 2-10%; and the content of the solid photocatalyst loaded on the honeycomb activated carbon bed layer II is 5-20%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 is a structural representation of the ozone-photocatalysis reactor provided in Example 1;

[0048] wherein, 1-shell layer; 2-activated carbon layer; 3-honeycomb activated carbon bed layer I; 4-honeycomb activated carbon bed layer II; 5-transparent quartz tubes; 6-water inlet; 7-gas inlet; 8-ultraviolet light tubes; 9-water outlet; 10-gas outlet; 11-gas distributor.

DETAIL DESCRIPTION

[0049] For the purpose of easy understanding the present disclosure, the following embodiments are listed below in the present disclosure. It will be apparent to those skilled in the art that the examples are merely illustrations of the present disclosure and should not be construed as specific limitations of the present disclosure.

EXAMPLE 1

[0050] FIG. 1 provided an ozone-photocatalysis reactor comprising a shell layer 1, inside which the followings were disposed sequentially from bottom to top:

[0051] (1) an activated carbon layer 2, the activated carbon layer 2 was a water-resistant honeycomb activated carbon bed having a square hole aperture less than or equal to 0.5 cm and loaded with a solid catalyst having a content less than or equal to 5%, for example 0.1%, 2%, 3.3%, and 4.4%, etc., preferably 0.1-5%, the height of the activated carbon layer was 1-5 meters;

[0052] wherein, the honeycomb activated carbon bed was preferably arranged in a staggered manner to increase the mass transfer effect of the sewage to be treated in the activated carbon layer 2 and to improve the reaction efficiency of ozonation; the staggered arrangement enabled any of the hole walls of the honeycomb activated carbon bed to align with the hole of the adjacent honeycomb activated carbon bed;

[0053] wherein, the aperture of the square hole of the activated carbon layer 2 was preferably 0.1-0.5 cm, for example, 0.2 cm, and 0.4 cm, etc., when the aperture of the square hole was less than 0.1 cm, the resistance of the activated carbon layer 2 was too large and the flow rate of water became small, which affected the treatment efficiency to some extent; when the aperture of the square hole was larger than 0.5 cm, the mass transfer efficiency was deteriorated and the water treatment effect was deteriorated.

[0054] The solid catalyst loaded on the activated carbon layer 2 was a transition metal oxide catalyst capable of being used for ozonation, preferably a metal-doped transition metal oxide catalyst for ozonation, and particularly preferably a metal-doped TiO.sub.2 catalyst, and further preferably a metal ion (selected from any one of Ni, Fe, Cu, and Mn) doped TiO.sub.2 catalyst.

[0055] If the content of the solid catalyst loaded on the activated carbon layer 2 was too low (<0.1%), the decomposition of ozone was insufficient, such that the solid catalyst could not fully play the role of decomposing ozone to generate hydroxyl radicals, if the content of the solid catalyst was too high (>5%), the decomposition of ozone was complete, the ozone cannot play its role when the sewage flowed through the honeycomb activated carbon bed layer I 3 and honeycomb activated carbon bed layer II 4, which was not conducive to the deep removal of the intermediate products.

[0056] Under the action of the solid catalyst loaded on the activated carbon layer 2, the sewage to be treated into which the reaction gas was introduced took place an ozonation reaction, through which the contaminants in the sewage to be treated were subjected to preliminary treatment.

[0057] (2) A photooxidation unit comprising a honeycomb activated carbon bed layer I 3, an ultraviolet light source layer and a honeycomb activated carbon bed layer II 4 disposed from bottom to top;

[0058] wherein, the thickness of the honeycomb activated carbon bed layer I 2 was 5-20 cm, for example 6 cm, 10 cm, and 15 cm, etc., the aperture of the square hole therein was 0.5-1 cm, for example 0.7 cm, and 0.8 cm, etc., and it was loaded with 2-10%, for example 3%, 5%, 7%, and 9%, etc., preferably 2-6% of solid photocatalyst; the thickness of the honeycomb activated carbon bed layer II 4 was 5-20 cm, for example 6 cm, 10 cm, and 15 cm, etc., the aperture of the square hole therein was 0.5-1 cm, for example 0.7 cm, and 0.8 cm, etc., and it was loaded with 5-20%, for example 7%, 10%, 16%, and 19%, etc., preferably 5-10% of solid photocatalyst; and the honeycomb activated carbon bed layer I 3 and the honeycomb activated carbon bed layer II 4 were water-resistant honeycomb activated carbon beds; the ultraviolet light source layer was composed of horizontally arranged cylindrical ultraviolet light tubes 8 covered with transparent quartz tubes 5, and the intensity of the emitting light of the ultraviolet light tube was 10-1000 mW/cm.sup.2, for example 50 mW/cm.sup.2, 120 mW/cm.sup.2, 350 mW/cm.sup.2, 700 mW/cm.sup.2, 850 mW/cm.sup.2, and 900 mW/cm.sup.2, etc.; and the distance of the honeycomb activated carbon bed layer I 3 and the honeycomb activated carbon bed layer II 4 from the transparent quartz tubes 5 of the ultraviolet light source was independently selected from 5-30 cm, for example 6 cm, 10 cm, 15 cm, and 25 cm, etc.

[0059] If the thickness of the honeycomb activated carbon bed layer I 3 and the honeycomb activated carbon bed layer II 4 was too large (e.g., >20 cm), the distance from the light source layer was too far, or the power of the light source layer was too small, etc., which will result in the light failing to be irradiated to the side of the honeycomb activated carbon bed layer I 3 and the honeycomb activated carbon bed layer II 4 away from the light source layer, the photocatalytic ozonation failed to occur in the area which was not irradiated by the light, thereby affecting the sewage treatment efficiency, causing the wastes of the activated carbon layer 2 and the catalyst loaded thereon. On the other hand, if the thickness of the honeycomb activated carbon bed layer I 3 and the honeycomb activated carbon bed layer II 4 was too small, the distance from the light source layer was too short, or the power of the light source layer was too large, etc., which will result in low utilization rate of light energy, thereby causing energy loss.

[0060] If the content of the solid photocatalyst loaded on the honeycomb activated carbon bed layer II 4 was high, the ozone in the sewage could be completely decomposed, and the photocatalytic ozonation in the honeycomb activated carbon bed layer I 3 and the honeycomb activated carbon bed layer II 4 was enhanced and the concentration of ozone in the discharged water was reduced, thereby avoiding the secondary pollution; but if it was too high, it would cause waste; therefore, the content of the solid photocatalyst loaded on the honeycomb activated carbon bed layer II 4 was preferably 5-10%.

[0061] In the photooxidation unit, the visible light and/or ultraviolet light emitted from the light source layer could be irradiated in the upper and lower directions at the same time, and under the action of the solid photocatalyst loaded on the honeycomb activated carbon bed layer 3 and the honeycomb activated carbon bed layer 4, the sewage from the activated carbon layer 2 further took place the photocatalytic ozonation, so that the non-degraded pollutants and the degraded intermediate products could be further processed.

[0062] (3) The reactor was disposed with a gas inlet 7 and a water inlet 6 below the activated carbon layer, and a water outlet 9 and a gas outlet 10 were disposed above the honeycomb activated carbon bed layer II 4 of the reactor; and a gas distributor 11 was arranged between the activated carbon layer and the gas inlet.

[0063] The ozone gas was passed into the gas inlet 7 and the sewage to be treated was passed into the water inlet 6.

[0064] The sewage to be treated sequentially flowed through the activated carbon layer 2 to take place the adsorption and ozonation reaction, through the adsorption, ozonation, photocatalysis and photocatalytic ozonation taking place in the honeycomb activated carbon bed layer II 3, the photochemical reaction taking place in the ultraviolet light layer, and the adsorption, photocatalysis, ozonation and photocatalytic ozonation taking place in the honeycomb activated carbon bed layer III 4, the purpose of deep removal of the contaminants in the water could be achieved by multi-stage different reactions.

[0065] The working principle of the ozone-photocatalysis reactor provided in Example 1 was as follows:

[0066] Ozone entered the bottom of the reactor via the gas inlet 7 and the sewage to be treated entered the bottom of the reactor via the water inlet 6, the ozone from the gas inlet 7 passed through the gas distributor 11, then was mixed evenly with the sewage to be treated, and then the mixture flowed through the honeycomb activated carbon bed layer 2; the activated carbon layer 2 was made up by stacking many water-resistant honeycomb activated carbon, the interior of which was square holes with a aperture less than 0.5 cm, the solid catalyst loaded on the hole walls was a metal ion doped TiO.sub.2 catalyst; a large number of staggered water channels were formed within the activated carbon layer 2, which facilitated the full contact of the sewage, the ozone and the loaded catalyst; ozonation reaction occurred in each channel of the square hole, adsorption of pollutants and catalytic ozonation reaction occurred on the hole walls; the decomposition of the ozone on the hole walls produced oxide species such as hydroxyl radicals, superoxide radicals and singlet oxygen, etc., which would oxidize and decompose the organic pollutants in the sewage; therefore adsorption, ozonation, and catalytic ozonation reactions would occur in the activated carbon layer 2, so that the organic pollutants in the sewage were oxidized into intermediate products, water and carbon dioxide.

[0067] After the sewage flowed through the activated carbon layer 2, it entered the honeycomb activated carbon bed layer I 3 with a height of 5-20 cm. The ultraviolet light was irradiated downward from the top of the honeycomb activated carbon bed layer I 3, the photochemical reaction occurred in the square holes of the honeycomb activated carbon bed I 3, and the reaction of adsorption, ozonation and ozone photocatalysis etc., occurred in the square hole walls of the honeycomb activated carbon bed I 3 to form photogenerated holes and oxide species such as hydroxyl radicals and superoxide radicals, etc., which would further decompose the organic pollutants in the sewage and the intermediate products formed by the reaction in the activated carbon layer 2.

[0068] After the sewage flowed out of the honeycomb activated carbon bed layer I 3 into the ultraviolet light region, the photochemical reaction and ozone reaction occurred under the UV-irradiation, the incompletely decomposed ozone continued to oxidize the pollutants, the ozone and oxygen in the ozone gas could also be used as photogenerated electron capture agent, which improved the yield of photogenerated holes under the UV-irradiation, and the formation of holes with strong oxidizing ability also helped the further oxidative decomposition of the organic pollutants.

[0069] The sewage finally flowed into the honeycomb activated carbon bed layer II 4, the structure of which was very close to that of the honeycomb activated carbon bed layer I 3, but the content of catalyst loaded on the inner wall of the hole channel was higher; since the concentration of ozone after passing through three reaction regions had been greatly reduced, the higher content of catalyst loaded on the honeycomb activated carbon bed layer II 4 made the decomposition of ozone more thoroughly to avoid the secondary pollution of ozone dissolved in the discharged water; the reaction occurring in the honeycomb activated carbon bed layer II 4 was also identical to that in the honeycomb activated carbon bed layer I 3, including reactions such as adsorption, ozonation, and ozone photocatalysis, etc., which would produce photogenerated holes and oxide species such as hydroxyl radicals and superoxide radicals, etc., to deeply mineralize the organic pollutants and the oxidation intermediate products formed during the previous stages.

[0070] After the sewage flowed out of the honeycomb activated carbon bed layer II 4, the off-gas was discharged from the top gas outlet 10, and the treated water flowed out from the upper water outlet 9.

EXAMPLE 2

[0071] An ozone-photocatalysis reactor was provided, the difference of which from that of Example 1 was that two photooxidation units were disposed and the light sources in both of the photooxidation units were visible light sources; a total of four honeycomb activated carbon bed layers were contained in the two photooxidation units, the thickness of which from bottom to top respectively was 5-10 cm, 5-10 cm, 5-20 cm, and 5-20 cm; the four bed layers were all loaded with metal ion doped TiO.sub.2 catalyst, and the content of the solid catalyst loaded thereon respectively was 2-10%, 2-10%, and 5-20%, preferably 2-4%, 2-4%, and 5-10%.

APPLICATION EXAMPLE 1

[0072] The ozone-photocatalysis reactor provided in Example 1 was used to carry out the sewage treatment, the volume flow rate of the sewage was 1 m.sup.3/h, the COD of the sewage was 150 mg/L, and the mass flow rate of ozone was 120 g/h. After treatment, the COD in the sewage was less than 50 mg/L.

[0073] Applicant has stated that although the detailed process equipment and process flow of the present disclosure have been described by the above embodiments in the present disclosure, the present disclosure is not limited thereto, that is to say, it is not meant that the present disclosure has to be implemented depending on the above detailed process equipment and process flow. It will be apparent to those skilled in the art that any improvements made to the present disclosure, equivalent replacements to the raw materials of the products of the present disclosure and addition of adjuvant ingredients, and selections of the specific implementations, etc., all fall within the protection scope and the disclosure scope of the present disclosure.