METHOD FOR REMOVING PPCPS IN DRINKING WATER TREATMENT PROCESS

Abstract

A method for removing PPCPs in a drinking water treatment process, includes the following operations: introducing, by using a manner of bottom microporous aeration, a mixture gas of O.sub.2 and O.sub.3 in which a volume percentage of O.sub.3 is 5% to 10% to an ozone contact reaction column (1) in which a cathode (3) and an anode (2) are disposed at the bottom, and a direct current is applied to the cathode and the anode; while the mixture gas is being introduced, adding, to the ozone contact reaction column (1), PPCPs containing water to be treated, with a hydraulic retention time of 10 s to 40 min, and discharging the water in real time. Further disclosed is the use of the method for removing PPCPs in a drinking water treatment process in preparation of drinking water.

Claims

1. A method for removing pharmaceuticals and personal care products (PPCPs) in a drinking water treatment process, characterized in that the method comprises the following operations: introducing, by using a manner of bottom microporous aeration, a mixed gas of O.sub.2 and O.sub.3 in which a volume percentage of O.sub.3 is 5% to 10% into an ozone contact column, at the bottom of which a cathode and an anode are disposed, and a direct current is applied to the cathode and the anode; while the mixed gas is being introduced, adding PPCPs-containing water to be treated to the ozone contact column, where the hydraulic retention time of 10 s to 40 min, and discharging water in real time; the ratio of the amount of the introduced O.sub.3 to the volume of the water to be treated is 0.1 to 10 mg/L, and the current density at the cathode is 0.1 to 20 mA/cm.sup.2.

2. The method according to claim 1, characterized in that the PPCPs comprise one or more of ibuprofen, diclofenac, diazepam, iopromide, meprobamate, primidone, and clofibric acid.

3. The method according to claim 1, characterized in that the water to be treated is surface water or groundwater; wherein the concentration of the PPCPs is 0.01 ng/L to 20 mg/L, TOC is 0 to 10 mg/L, pH is 2 to 12, and the conductivity is greater than 300 S/m.

4. The method according to claim 3, characterized in that the water to be treated is surface water or groundwater; wherein the concentration of the PPCPs is 2 ng/L to 100 ng/L, TOC is 0 to 6.3 mg/L, pH is 4.0 to 10.5, and the conductivity is greater than 300 S/m.

5. The method according to claim 1, characterized in that the mixed gas is prepared by the following method: introducing O.sub.2 into an ozone generator to obtain a mixed gas of O.sub.2 and O.sub.3 in which a volume percentage of O.sub.3 is 5% to 10%.

6. The method according to claim 1, characterized in that in the electrodes, the anode area is 5 cm.sup.2 to 20 cm.sup.2, and the anode is selected from the group consisting of Pt electrode, graphite electrode, boron-doped diamond electrode, Pt/C electrode, ruthenium-iridium-plated titanium electrode, ruthenium-plated titanium electrode, platinum-plated titanium electrode, iridium-plated titanium-based electrode, rhodium-plated titanium-based electrode, iridium dioxide-plated titanium-based electrode, stainless steel electrode, nickel electrode, and alloy electrode containing two or more transition metals; the alloy electrode containing two or more transition metals is an aluminum alloy electrode, a titanium alloy electrode, a copper alloy electrode or a zinc alloy electrode; the cathode area is 5 cm.sup.2 to 20 cm.sup.2; the cathode is selected from the group consisting of graphite electrode, glassy carbon electrode, activated carbon fiber electrode and gas diffusion electrode; the gas diffusion electrode is carbon paper/cloth/felt-polytetrafluoroethylene electrode, activated carbon-polytetrafluoroethylene electrode, carbon black-polytetrafluoroethylene electrode, carbon nanotube-polytetrafluoroethylene electrode, or graphene-polytetrafluoroethylene electrode.

7. The method according to claim 6, characterized in that, the anode is a Pt plate electrode or a ruthenium-iridium-plated titanium electrode with an area of 20 cm.sup.2; and the cathode is a carbon paper-polytetrafluoroethylene electrode, a carbon black-polytetrafluoroethylene electrode, or a graphite electrode with an area of 20 cm.sup.2.

8. The method according to claim 1, characterized in that the method comprises the following operations: introducing O.sub.2 into an ozone generator to obtain a mixed gas of O.sub.2 and O.sub.3 in which a volume percentage of O.sub.3 is 5% to 10%, continuously and uniformly introducing, by using a manner of bottom microporous aeration, the mixed gas to an ozone contact column, at the bottom of which a cathode and an anode are disposed and a direct current is continuously applied to the cathode and the anode; while the mixed gas is being introduced, continuously adding PPCPs-containing water to be treated to the ozone contact column at a constant rate, with a hydraulic retention time of 10 to 20 min, and discharging the water in real time; the ratio of the amount of the introduced O.sub.3 to the volume of the water to be treated is 1.8 to 6.2 mg/L; the anode is a Pt plate electrode or a ruthenium-iridium-plated titanium electrode with an area of 20 cm.sup.2; the cathode is a carbon paper-polytetrafluoroethylene electrode, a carbon black-polytetrafluoroethylene electrode, or a graphite electrode with an area of 20 cm.sup.2; and the current density at the cathode is 3 to 7 mA/cm.sup.2.

9. The method according to claim 1, wherein one or more operations among introducing the mixed gas into the ozone contact column, applying direct current to the electrodes at two ends, adding the water to be treated to the ozone contact column, and discharging the water, are carried out intermittently.

10. A method for producing drinking water comprising implementing the method for removing PPCPs according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a schematic diagram of a device used in Examples of the present invention; in this FIGURE, 1 represents a reaction column; 2 represents an anode; 3 represents a cathode; 4 represents a water inlet; 5 represents a water outlet; 6 represents a gas distribution plate; 7 represents an air inlet; 8 represents an air outlet; 9 represents peristaltic pump; 10 represents a direct current power supply; 11 represents an ozone generator; 12 represents an ozone detector; 13 represents a water tank; and 14 represents an oxygen cylinder.

SPECIFIC MODES FOR CARRYING OUT THE EMBODIMENTS

[0029] The following examples are intended to illustrate the present invention but are not intended to limit the scope of the present invention. If not specified, the technical means used in Examples are conventional means well known to a person skilled in the art.

[0030] The water bodies to be treated in each embodiment are surface water taken from a reservoir in Beijing and treated by precipitation. The initial concentration of PPCPs in each Example was controlled within a range of 2 to 100 ng/L, which covering the concentration range of PPCPs in surface water or groundwater in general suburbs.

Example 1

[0031] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0032] The device used in this Example was shown in FIG. 1.

[0033] The water body was treated according to the following operations:

[0034] O.sub.2 was introduced into an ozone generator to obtain a mixed gas of O.sub.2 and O.sub.3 in which a volume percentage of O.sub.3 is 10%. By using a manner of bottom microporous aeration, the mixed gas was introduced continuously at a constant rate to an ozone contact column, in which a cathode and an anode are disposed at the bottom and a direct current is applied to the cathode and the anode; while the mixed gas is being introduced, the PPCPs-containing water body to be treated was injected continuously at a constant rate to the ozone contact column with a hydraulic retention time of 20 min, and the water body was discharged in real time.

[0035] The ratio of the amount of the introduced O.sub.3 to the volume of the water to be treated is 3.2 mg/L;

[0036] The anode is a Pt plate electrode with an area of 20 cm.sup.2 (purchased from Suzhou Borui Industrial Material Technology Co., Ltd.), and the cathode is a carbon paper-polytetrafluoroethylene electrode with an area of 20 cm.sup.2 (purchased from Shanghai Hesen Electric Co., Ltd.); A direct current was continuously applied to the cathode and the anode with a current density of 4 mA/cm.sup.2.

[0037] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 1.

TABLE-US-00001 TABLE 1 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration 6.4 7.6 9.5 9.8 8.7 5.1 7.9 after treatment

[0038] By detecting at the water outlet, it was found that there was no residual H.sub.2O.sub.2 in the water after the reaction (the water after the reaction was taken and reacted with titanium potassium oxalate, the absorbance was measured, and it was confirmed that there was no H.sub.2O.sub.2), hence the corrosion problem of the pipe network caused by H.sub.2O.sub.2 will not occur.

[0039] The unreacted O.sub.2 and O.sub.3 were collected at an exhaust gas outlet and re-introduced into the ozone generator to produce the mixed gas of O.sub.2 and O.sub.3 so as to reduce gas consumption.

Example 2

[0040] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0041] Compared with Example 1, the difference in the treatment method lied in that the current density was 2 mA/cm.sup.2.

[0042] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 2.

TABLE-US-00002 TABLE 2 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration 12.1 15.3 23.3 24.1 19.8 10.3 17.8 after treatment

Example 3

[0043] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0044] Compared with Example 1, the difference in the treatment method lied in that the current density was 5 mA/cm.sup.2.

[0045] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 3.

TABLE-US-00003 TABLE 3 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration <0.1 3.2 4.1 4.8 3.9 <0.1 3.5 after treatment

Example 4

[0046] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 4.03.

[0047] Compared with Example 1, the difference in the treatment method lied in that a Pt plate electrode with an area of 20 cm.sup.2 was used as the anode, and a graphite electrode with an area of 20 cm.sup.2 (purchased from Shanghai Hesen Electric Co., Ltd.) was used as cathode.

[0048] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 4.

TABLE-US-00004 TABLE 4 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration 7.1 7.9 9.6 9.7 8.9 6.4 8.3 after treatment

Example 5

[0049] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH value was 8.25.

[0050] The treatment method was the same as that in Example 4.

[0051] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 5.

TABLE-US-00005 TABLE 5 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration 6.3 7.7 9.4 9.6 8.5 5.8 8.3 after treatment

Example 6

[0052] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 10.25.

[0053] The treatment method is the same as that in Example 4.

[0054] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 6.

TABLE-US-00006 TABLE 6 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration 6.9 7.9 9.4 9.6 8.9 6.3 7.9 after treatment

Example 7

[0055] In the water body to be treated, the initial TOC value was 2.05 mg/L and the initial pH was 8.0.

[0056] Compared with Example 1, the difference in the treatment method lied in that the anode was a Pt plate electrode with an area of 20 cm.sup.2, and the cathode was a carbon black-polytetrafluoroethylene electrode with an area of 20 cm.sup.2.

[0057] After detection, all the concentrations of ibuprofen, diclofenac, diazepam, iopromide, meprobamate, primidone, and clofibric acid in the water before treatment were 100 ng/L; and all of the concentrations of PPCPs in the treated water body were less than 5 ng/L.

Example 8

[0058] In the water body to be treated, the initial TOC value was 4.2 mg/L and the initial pH was 8.0.

[0059] The treatment method was the same as that in Example 7.

[0060] After detection, all the concentrations of ibuprofen, diclofenac, diazepam, iopromide, meprobamate, primidone, and clofibric acid in the water before treatment were 100 ng/L; and all the concentrations of PPCPs in the treated water body were less than 10 ng/L.

Example 9

[0061] In the water body to be treated, the initial TOC value was 6.3 mg/L and the initial pH was 8.0.

[0062] The treatment method was the same as that in Example 7.

[0063] After detection, all the concentrations of ibuprofen, diclofenac, diazepam, iopromide, meprobamate, primidone, and clofibric acid in the water before treatment were 100 ng/L; and all the concentrations of PPCPs in the treated water body were less than 10 ng/L.

Example 10

[0064] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0065] Compared with Example 1, the difference in the treatment method lied in that the anode was a ruthenium-iridium-plated titanium electrode with an area of 20 cm.sup.2 (purchased from Suzhou Bo Rui Industrial Material Technology Co., Ltd.), the cathode was a carbon paper-polytetrafluoroethylene electrode with an area of 20 cm.sup.2 (purchased from Shanghai Hesen Electric Co., Ltd.), and the current density was 5 mA/cm.sup.2.

[0066] After detection, all the concentrations of ibuprofen, diclofenac, diazepam, iopromide, meprobamate, primidone, and clofibric acid in the water before treatment were 2 ng/L; and no PPCPs could be detected in the treated water. It can be seen that, the method provided by the present invention can efficiently and thoroughly remove low-concentration PPCPs in water body.

Example 11

[0067] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0068] The treatment method was the same as that in Example 10.

[0069] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 7.

TABLE-US-00007 TABLE 7 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 50 50 50 50 50 50 50 before treatment Concentration 1.4 1.8 2.3 2.4 2.1 1.3 1.9 after treatment

Example 12

[0070] In the water to be treated, the initial TOC value was 2.8 mg/L and the initial pH value was 8.0.

[0071] The treatment method was the same as that in Example 10.

[0072] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 8.

TABLE-US-00008 TABLE 8 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 10 10 10 10 10 10 10 before treatment Concentration <0.1 <0.1 0.8 0.8 0.7 <0.1 0.5 after treatment

Example 13

[0073] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0074] The treatment method was the same as that in Example 10.

[0075] After detection, all the concentrations of ibuprofen, diclofenac, diazepam, iopromide, meprobamate, primidone, and clofibric acid in the water before treatment were 100 ng/L; and all the concentrations of PPCPs in the treated water body were less than 5 ng/L.

Example 14

[0076] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0077] Compared with Example 1, the difference in the treatment method lied in that in this Example, the anode was a ruthenium-iridium-plated titanium electrode with an area of 20 cm.sup.2, and the cathode was a carbon paper-polytetrafluoroethylene electrode with an area of 20 cm.sup.2; the ratio of the amount of the introduced O.sub.3 to the volume of the surface water to be treated was 1.8 mg/L, and a direct current was applied to the cathode and the anode with a current density of 3 mA/cm.sup.2.

[0078] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 9.

TABLE-US-00009 TABLE 9 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration 7.4 7.8 9.6 9.7 8.9 7.1 8.1 after treatment

Example 15

[0079] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0080] Compared with Example 1, the difference in the treatment method lied in that in this Example, the anode was a ruthenium-iridium-plated titanium electrode with an area of 20 cm.sup.2, and the cathode was a carbon paper-polytetrafluoroethylene electrode with an area of 20 cm.sup.2; the ratio of the amount of the introduced O.sub.3 to the volume of the surface water to be treated was 2.8 mg/L, and a direct current was applied to the cathode and the anode with a current density of 3 mA/cm.sup.2.

[0081] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 10.

TABLE-US-00010 TABLE 10 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration 7.4 7.9 9.7 9.9 8.9 6.9 7.8 after treatment

Example 16

[0082] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0083] Compared with Example 1, the difference in the treatment method lied in that: in this Example, the anode was a ruthenium-iridium-plated titanium electrode with an area of 20 cm.sup.2, and the cathode was a carbon paper-polytetrafluoroethylene electrode with an area of 20 cm.sup.2; the ratio of the amount of the introduced O.sub.3 to the volume of the surface water to be treated was 4.1 mg/L, and a direct current was applied to the cathode and the anode with a current density of 6 mA/cm.sup.2.

[0084] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 11.

TABLE-US-00011 TABLE 11 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration <0.1 <0.1 4.5 4.8 3.7 <0.1 2.9 after treatment

Example 17

[0085] In the water body to be treated, the initial TOC value was 2.8 mg/L and the initial pH was 8.0.

[0086] Compared with Example 1, the difference in the treatment method lied in that in this Example, the anode was a ruthenium-iridium-plated titanium electrode with an area of 20 cm.sup.2, and the cathode was a carbon paper-polytetrafluoroethylene electrode with an area of 20 cm.sup.2; the ratio of the amount of the introduced O.sub.3 to the volume of the surface water to be treated was 6.2 mg/L, and a direct current was applied to the cathode and the anode with a current density of 7 mA/cm.sup.2.

[0087] After detection, the concentrations of typical PPCPs before and after treatment were shown in Table 12.

TABLE-US-00012 TABLE 12 Concentrations of typical PPCPs before and after treatment (ng/L) Clofibric PPCPs Ibuprofen Diclofenac Diazepam Iopromide Meprobamate Primidone acid Concentration 100 100 100 100 100 100 100 before treatment Concentration <0.1 <0.1 4.3 4.7 3.9 <0.1 3.1 after treatment

[0088] The above Examples illustrate that this method utilizes an on-line electrochemical method to generate an oxidation synergy of H.sub.2O.sub.2 and O.sub.3 to treat typical PPCPs that are difficult to degrade such as ibuprofen, diclofenac, and primidone and the like. This method has the following characteristics and advantages: it does not need to add chemical agents, so it will not produce secondary pollution; because of the low voltage and current density of the applied electric field, there is no potential safety hazard, such that the method is easy for practical application; this method has a very good removal effect on COD and ammonia-nitrogen, and it is low in cost, economical and applicable, which makes it an efficient and rapid method for removing low concentration PPCPs. In addition, the overall structure of the reaction device also has good stability.

[0089] Although the present invention has been described above in detail with general description and specific embodiments, it is obvious to a person skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention fall within the protection scope of the present invention.