Method for treating reverse osmosis concentrated water

Abstract

A method for treating reverse osmosis concentrated water, comprises adding precipitant and oxidant to reverse osmosis concentrated water for treatment, filtering to obtain clear liquid, and adding catalyst for water treatment to clear liquid for catalytic oxidation to obtain a first-stage treated water. Optionally, the liquid may be subjected after catalytic oxidation to an adsorption treatment; performing reverse osmosis treatment on first-stage treated water to obtain second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water; and adding oxidant to second-stage reverse osmosis concentrated water for oxidation treatment to obtain directly discharged effluent water. The obtaining of effluent water may further comprise subjecting liquid after oxidation treatment to adsorption treatment. The above method can recycle 75-85 wt % of water, and operates easily. Thereby, improvement to overall utilization rate of water, and treatment of little remaining water is met to effluent standard for reduction of environmental pollution and economic investment.

Claims

1. A treating method of reverse osmosis concentrated water, characterized in that, comprising the following steps: (1) adding a precipitant and an oxidant to reverse osmosis concentrated water for treatment, filtering to obtain a filtered liquid, and adding a catalyst for water treatment to the filtered liquid for catalytic oxidation to obtain first-stage treated water; wherein the obtaining of the first-stage treated water further comprises subjecting the liquid after catalytic oxidation to an adsorption treatment; (2) performing reverse osmosis treatment on the first-stage treated water obtained in step (1), to obtain second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water, wherein the second-stage reverse osmosis product water is recycled; (3) adding an oxidant to the second-stage reverse osmosis concentrated water obtained in step (2) for oxidation treatment to obtain effluent water which is used to for directly discharging; wherein the obtaining of the effluent water further comprises subjecting the liquid after oxidation treatment to an adsorption treatment.

2. The treating method according to claim 1, characterized in that, the COD of the reverse osmosis concentrated water is less than or equal to 300 ppm; the Ca.sup.2+ content of the reverse osmosis concentrated water is 0-1000 ppm; the Mg.sup.2+ content is 0-500 ppm.

3. The treating method according to claim 1, characterized in that, in step (1), the precipitant is selected from the group consisting of NaOH, KOH, Na.sub.2CO.sub.3, NaHCO.sub.3, and any combination thereof.

4. The treating method according to claim 1, characterized in that, in step (1), the oxidant is selected from the group consisting of a compound containing available chlorine, H.sub.2O.sub.2, and any combination thereof, the compound containing available chlorine is selected from the group consisting of NaClO, NaClO.sub.3, Cl.sub.2, ClO.sub.2, and any combination thereof.

5. The treating method according to claim 1, characterized in that, in step (1), the oxidant is NaClO, the precipitant is Na.sub.2CO.sub.3 and NaOH, and the precipitant and oxidant are derived from a waste water containing NaClO, Na.sub.2CO.sub.3 and NaOH; wherein the waste water has available chlorine content that is 2-4 wt %, the Na.sub.2CO.sub.3 content is 5-10 wt %, and the NaOH content is 0.1-2 wt %.

6. The treating method according to claim 5, characterized in that, in step (1), the dosage of the chlorine alkali industry waste water is 2-50 kg per ton of the reverse osmosis concentrated water.

7. The treating method according to claim 1, characterized in that, in step (1), the reaction time of the catalytic oxidation is 0.5-2 h.

8. The treating method according to claim 1, characterized in that, in step (1), the catalyst comprises aluminium oxide and nickel, iron, manganese and cerium loaded on the aluminium oxide in the form of oxide; based on the weight of the aluminium oxide, the contents of the following components in the catalyst are: nickel 5.0-20 wt %; iron 0.5-5.5 wt %; manganese 0.5-3.5 wt %; cerium 1.5-3.0 wt %.

9. The treating method according to claim 8, characterized in that, the catalyst comprises cerium modified aluminium oxide carrier and nickel, iron, manganese and cerium loaded on the cerium modified aluminium oxide carrier in the form of oxide; the cerium modified aluminium oxide carrier comprises aluminium oxide and cerium loaded on the aluminium oxide in the form of oxide; based on the weight of the aluminium oxide, the cerium content of the cerium modified aluminium oxide carrier is 1.0-2.0 wt %.

10. The treating method according to claim 9, characterized in that, based on the weight of the aluminium oxide, the cerium loaded on the cerium modified aluminium oxide carrier in the catalyst has a content of 0.5-2.0 wt %.

11. The treating method according to claim 1, characterized in that, in step (1), before adding the precipitant and oxidant to the reverse osmosis concentrated water, adjusting the pH of the reverse osmosis concentrated water to 6-12.

12. The treating method according to claim 11, characterized in that, in step (1), adjusting the pH of the reverse osmosis concentrated water with a pH regulator, wherein the pH regulator is an alkaline pH regulator, and the alkaline pH regulator is selected from a group consisting of NaOH, KOH, Ca(OH).sub.2, Mg(OH).sub.2, ammonia water, and any combination thereof.

13. The treating method according to claim 11, characterized in that, in step (1), before adding the catalyst to the filtered liquid, adjusting the pH of the filtered liquid to 6-9.

14. The treating method according to claim 13, characterized in that, the method comprising the following steps: (1) firstly adjusting the pH of the reverse osmosis concentrated water to 9.5-11.5, then adding the precipitant and oxidant for treatment thereinto, filtering to obtain the filtered liquid, adjusting pH of the filtered liquid to be 7-8, wherein the filtering is with a multi-media filter, adding the catalyst to the obtained filtrate for catalytic oxidation, to obtain a reaction liquid, and then subjecting the reaction liquid to an adsorption treatment in an adsorption apparatus to obtain first-stage treated water; wherein the catalyst in step (1) comprises cerium modified aluminium oxide carrier and nickel, iron, manganese and cerium loaded on the cerium modified aluminium oxide carrier in the form of oxide; the cerium modified aluminium oxide carrier comprises aluminium oxide and cerium loaded on the aluminium oxide in the form of oxide; based on the weight of the aluminium oxide, the contents of the following components in the catalyst are: nickel 5.5-12.0 wt %; iron 1.5-5.0 wt %; manganese 1.0-3.0 wt %; cerium 2.0-2.8 wt %; and based on the weight of the aluminium oxide, the cerium content of the cerium modified aluminium oxide carrier is 1.2-1.5 wt %, (2) performing reverse osmosis treatment on the first-stage treated water obtained in step (1) to obtain second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water, wherein the second-stage reverse osmosis product water is recycled; (3) wherein the oxidant is sodium hypochlorite, and adding sodium hypochlorite to the second-stage reverse osmosis concentrated water obtained in step (2) for oxidation treatment to obtain an oxidation reaction liquid, adjusting the pH of the oxidation reaction liquid to 6-9, then adding a reductant thereinto to remove excess sodium hypochlorite, and then subjecting the obtained liquid to an adsorption treatment in an adsorption apparatus, to obtain effluent water, wherein the effluent water is used for directly discharging.

15. The treating method according to claim 2, characterized in that, the catalyst comprises cerium modified aluminium oxide carrier and nickel, iron, manganese and cerium loaded on the cerium modified aluminium oxide carrier in the form of oxide; the cerium modified aluminium oxide carrier comprises aluminium oxide and cerium loaded on the aluminium oxide in the form of oxide; based on the weight of the aluminium oxide, the cerium content of the cerium modified aluminium oxide carrier is 1.0-2.0 wt %; based on the weight of the aluminium oxide, the contents of the following components in the catalyst are: nickel 5.0-20 wt %; iron 0.5-5.5 wt %; manganese 0.5-3.5 wt %; cerium 1.5-3.0 wt %.

16. The treating method according to claim 1, characterized in that, the COD of the reverse osmosis concentrated water is 50-250 ppm; the Ca.sup.2+ content of the reverse osmosis concentrated water is 50-500 ppm; the Mg.sup.2+ content is 50-200 ppm; the SiO.sub.2 content is 10-150 ppm; and in step (1), the precipitant is Na.sub.2CO.sub.3, NaHCO.sub.3, or any combination thereof, and the oxidant is NaClO, H.sub.2O.sub.2, or any combination thereof.

17. The treating method according to claim 5, characterized in that, in step (1), the dosage of the chlorine alkali industry waste water is 2-40 kg per ton of the reverse osmosis concentrated water, and the reaction time of the catalytic oxidation is 0.5-1.5 h.

18. The treating method according to claim 8, characterized in that, based on the weight of the aluminium oxide, the contents of the following components in the catalyst are: nickel 5.5-12.0 wt %; iron 1.5-5.0 wt %; manganese 1.0-3.0 wt %; cerium 2.0-2.8 wt %.

19. The treating method according to claim 9, characterized in that, based on the weight of the aluminium oxide, the cerium content of the cerium modified aluminium oxide carrier is 1.2-1.5 wt %; and based on the weight of the aluminium oxide, the cerium loaded on the cerium modified aluminium oxide carrier in the catalyst has a content of 0.6-1.5 wt %.

20. The treating method according to claim 11, characterized in that, in step (1), before adding the precipitant and oxidant to the reverse osmosis concentrated water, adjusting the pH of the reverse osmosis concentrated water to 9-11; and in step (1), adjusting the pH of the reverse osmosis concentrated water with a pH regulator, wherein the pH regulator is an alkaline pH regulator, and the alkaline pH regulator is NaOH, KOH, or any combination thereof; and in step (1), before adding the catalyst to the filtered liquid, adjusting the pH of the filtered liquid to 7-8.

Description

EMBODIMENTS

(1) The technical solutions of the present invention and the effects thereof are further illustrated by the following specific examples. The following examples are only for explaining the contents of the present invention, and are not intended to limit the scope of the present invention. Simple changes to the present invention without departing from the spirit of the present invention are within the scope as claimed in the invention.

(2) The apparatus used in Examples 1-11 and Comparative Examples 1-3 of the present invention were as follows:

(3) Plate and frame filter press, model XMKG70/1000-U, purchased from Wuxi General Machinery Co., Ltd.;

(4) Oxidation tower, multi-media filter, activated carbon adsorption tower, security filter, sand filter apparatus, microfiltration apparatus and roll reverse osmosis membrane module, all of the above were purchased from Maiwang Environmental Engineering Technology Co., Ltd.;

(5) Reverse osmosis membrane, model SWC series seawater desalination membrane, purchased from Hydranautics Nitto Denko, U.S.; activated carbon, purchased from Yantai General Activated Carbon Co., Ltd.;

(6) Muffle furnace, model VULCAN 3-1750, purchased from Neytech Inc., U.S.

(7) In Examples 1 to 11 and Comparative Examples 1 to 3 of the present invention, the raw materials were as follows:

(8) NaClO, Na.sub.2CO.sub.3, and NaOH, analytically pure, purchased from Xilong Chemical Co., Ltd.;

(9) PAC, analytically pure, purchased from Tianjin Kermel Chemical Reagent Co., Ltd.;

(10) PAM, model AN923SH, purchased from the SNF Floerger, France;

(11) Na.sub.2SO.sub.3, analytically pure, purchased from Sinopharm Chemical Reagent Co., Ltd.;

(12) Hydrochloric acid, 37 wt %, purchased from Sinopharm Chemical Reagent Co., Ltd.;

(13) FeSO.sub.4.7H.sub.2O, analytically pure, purchased from Xilong Chemical Co., Ltd.;

(14) H.sub.2O.sub.2 solution, 30 wt %, purchased from Sinopharm Chemical Reagent Co., Ltd.;

(15) Nickel nitrate, iron nitrate, cerium nitrate and manganese nitrate, analytically pure, purchased from Xilong Chemical Co., Ltd.;

(16) Ethanol, analytically pure, purchased from Sinopharm Chemical Reagent Co., Ltd.

Example 1: Preparation of 1# Catalyst

(17) 15 g of spherical aluminum oxide carrier (about 50 ml) from the Shandong Zibo Wufeng Aluminum Magnesium Co., Ltd. was taken and placed in a vacuum impregnation bottle for vacuum pretreatment, the vacuum pretreatment time was 30 min, and the vacuum degree was 96.0 KPa; at the same time, 12 ml of nickel nitrate aqueous solution containing 0.15 g/ml of nickel, 2.3 ml of iron nitrate aqueous solution containing iron of 0.10 g/ml, 3.0 ml of manganese nitrate aqueous solution containing manganese of 0.10 g/ml, and 2.0 ml of cerium nitrate aqueous solution containing cerium 0.15 g/ml were taken and added to an ethanol solution having an ethanol concentration of 10 wt % so as to prepare an impregnation liquid having a total volume of 25 ml. The above impregnation liquid was added to the vacuum impregnation bottle loaded with the above spherical aluminum oxide carrier, uniformly mixed. Then the above-mentioned spherical aluminum oxide carrier was subjected to an equal volume impregnation for 30 min, taken out, and dried in an oven at 110 C. for 3 h, and then calcined at 500 C. for 6 h in a muffle furnace so as to obtain 1# catalyst.

(18) In the obtained 1# catalyst, based on the weight of the aluminum oxide, the contents of the components were as follows: nickel 12.0 wt %, iron 1.5 wt %, manganese 2.0 wt %, and cerium 2.0 wt %.

Example 2: Preparation of 2# Catalyst

(19) 15 g of the spherical aluminum oxide carrier (about 30 ml) from Yantai Baichuan Huitong Technology Co., Ltd. was taken and placed in a vacuum impregnation bottle for vacuum pretreatment, the vacuum pretreatment time was 30 min and the vacuum degree was 98.0 KPa; meanwhile, 16 ml of nickel nitrate aqueous solution containing 0.15 g/ml of nickel, 0.9 ml of iron nitrate aqueous solution containing 0.10 g/ml of iron, 1.5 ml of manganese nitrate aqueous solution containing 0.10 g/ml of manganese, 2.5 ml of cerium nitrate aqueous solution containing 0.15 g/ml of cerium were taken and added into deionized water to prepare an impregnation liquid with a total volume of 21 ml. The above impregnation liquid was added to the vacuum impregnation bottle loaded with the above spherical aluminum oxide carrier and uniformly mixed. Then the above-mentioned spherical aluminum oxide carrier was subjected to an equal volume impregnation for 60 min, taken out, and dried in an oven at 130 C. for 2 h, then calcined at 480 C. for 6 h in a muffle furnace to obtain 2# catalyst.

(20) In the obtained 2# catalyst, based on the weight of the aluminum oxide, the contents of the following components were as follows: nickel 16.0 wt %, iron 0.6 wt %, manganese 1.0 wt %, cerium 2.5 wt %.

Example 3: Preparation of 3# Catalyst

(21) 15 g of spherical aluminum oxide carrier (about 30 ml) from Shandong Yantai Baichuan Huitong Technology Co., Ltd. was taken and placed in vacuum impregnation bottle for vacuum pretreatment, and vacuum pretreatment time was 20 min, the vacuum degree was 97.5 KPa; 6.0 ml of a cerium nitrate aqueous solution containing 0.05 g/ml of cerium was added to an ethanol aqueous solution having an ethanol concentration of 30 wt %, so as to prepare an impregnation liquid with a volume of 21 ml. The impregnation liquid was added to the vacuum impregnation bottle and uniformly mixed to perform an equal volume impregnation on the spherical aluminum oxide carrier for 30 min, then the aluminum oxide carrier was taken out, and dried in an oven at 120 C. for 3 h, then calcined in a muffle furnace at 500 C. for 4 h, to obtain an cerium modified aluminum oxide carrier. In the cerium modified aluminum oxide carrier, the content of cerium was 2.0 wt % based on the weight of aluminum oxide.

(22) 15 g of the above cerium modified aluminum oxide carrier (about 30 ml) was taken and placed in a vacuum impregnation bottle for vacuum pretreatment, the vacuum pretreatment time was 30 min, the vacuum degree was 98.0 KPa; meanwhile 16 ml of nickel nitrate aqueous solution containing 0.15 g/ml of nickel, 0.9 ml of iron nitrate aqueous solution containing 0.10 g/ml of iron, 1.5 ml of manganese nitrate aqueous solution containing 0.10 g/ml of manganese, 1.5 ml of cerium nitrate containing cerium 0.05 g/ml of cerium were taken and added to deionized water to obtain an impregnation liquid with a total volume of 21 ml. The obtained impregnation liquid was added to the vacuum impregnation bottle containing the above-described cerium modified aluminum oxide carrier, and uniformly mixing to perform an equal volume impregnation on the above-mentioned cerium modified aluminum oxide carrier for 60 min, taken out, and dried in an oven at 130 C. for 2 h, then calcined in a muffle furnace at 480 C. for 6 h to obtain 3# catalyst.

(23) The physicochemical properties of the above-described spherical aluminum oxide carrier are as follows: having a particle size of 1.5-2.0 mm, a bulk density of 0.50 g/ml, a water absorption of 70 vol %, a specific surface area of 250 m.sup.2/g, a pore volume of 1.20 ml/g, and an average pore diameter of 130 nm.

(24) In the obtained 3# catalyst, based on the weight of the aluminum oxide, the contents of ingredients were as follows: nickel 16.0 wt %, iron 0.6 wt %, manganese 1.0 wt %, cerium 2.5 wt %.

Example 4: Preparation of 4# Catalyst

(25) 15 g of the spherical aluminum oxide carrier (about 50 ml) from the Shandong Zibo Wufeng Aluminum Magnesium Co., Ltd. was taken and placed in a vacuum impregnation bottle for vacuum pretreatment, the vacuum pretreatment time was 30 min, the vacuum degree was 98.0 KPa; 3.0 ml of a cerium nitrate aqueous solution containing 0.05 g/ml of cerium was added to an ethanol solution having an ethanol concentration of 20 wt % to prepare an impregnation liquid having a volume of 25 ml, and the impregnation liquid was added to the vacuum impregnation bottle and uniformly mixed to perform an equal volume impregnation on the above-mentioned spherical aluminum oxide carrier for 60 min, then the spherical aluminum oxide carrier was taken out, and dried in an oven at 120 C. for 2 h, and then calcined at 450 C. in a muffle furnace for 5 h to obtain a cerium modified aluminum oxide carrier. In the obtained cerium modified aluminum oxide carrier, the cerium content was 1.0 wt % based on the weight of aluminum oxide.

(26) 15 g of the above cerium modified aluminum oxide carrier (about 50 ml) was placed in a vacuum impregnation bottle for vacuum pretreatment, the vacuum pretreatment time was 30 min, and the vacuum degree was 96.0 KPa. Meanwhile, 12 ml of nickel nitrate aqueous solution containing 0.15 g/ml of nickel, 2.3 ml of iron nitrate aqueous solution containing iron of 0.10 g/ml, 3.0 ml of manganese nitrate aqueous solution containing 0.10 g/ml of manganese, 3.0 ml of cerium nitrate aqueous solution containing 0.05 g/ml of cerium were added to the ethanol aqueous solution having an ethanol concentration of 10 wt %, to obtain an impregnation liquid having a total volume of 25 ml. The obtained impregnation liquid was added to the vacuum impregnation bottle loaded with the above cerium modified aluminum oxide carrier and uniformly mixed to perform an equal volume impregnation on the above-mentioned cerium modified aluminum oxide carrier for 60 min. Then the cerium modified aluminum oxide carrier was taken out, and placed in an oven at 110 C. for 3 h, then calcined at 500 C. in a muffle furnace for 6 h to obtain 4# catalyst.

(27) The physicochemical properties of the above spherical aluminum oxide carrier are as follows: having a particle size of 1.0-1.5 mm, a bulk density of 0.30 g/ml, a water absorption of 50 vol %, a specific surface area of 150 m.sup.2/g, a pore volume of 1.80 ml/g, and an average pore diameter of 150 nm.

(28) In the obtained 4# catalyst, based on the weight of the aluminum oxide, the contents of ingredients were as follows: nickel 12.0 wt %, iron 1.5 wt %, manganese 2.0 wt %, and cerium 2.0 wt %.

(29) In the following examples, the sampling analysis results of reverse osmosis concentrated water in the raw materials used are shown in Table 4. The main components of the chlorine alkali industry waste water are shown in Table 5.

(30) TABLE-US-00004 TABLE 4 The sampling analysis results of reverse osmosis concentrated water Reverse osmosis concentrated COD/ TDS/ Suspension/ Mg.sup.2+/ SiO.sub.2/ NH.sub.4.sup.+/ water ppm ppm pH ppm ppm ppm ppm Ca.sup.2+/ppm Example 5 300 10000 9 1000 200 150 50 1000 Example 6 50 2000 6 50 50 50 5 200 Example 7 210 5000 7.2 122 120 30 15 500 Example 8 158 5000 8.1 500 500 120 45 800 Example 9 50 2000 6 50 50 50 5 200 Example 10 158 5000 8.1 500 500 120 45 800 Example 11 300 10000 9 1000 200 150 50 1000 Comparative 300 10000 9 1000 200 150 50 1000 Example 1 Comparative 50 2000 6 50 50 50 5 200 Example 2 Comparative 158 5000 8.1 500 500 120 45 800 Example 3

(31) TABLE-US-00005 TABLE 5 Main components of chlorine alkali industry waste water Chlorine alkali industry waste water NaClO/wt % Na.sub.2CO.sub.3/wt % NaOH/wt %/ Example 5-8 and 11, and 2 9 1 Comparative Example 3

Example 5: Treatment of Reverse Osmosis Concentrated Water (1# Catalyst+Chlorine Alkali Industry Waste Water)

(32) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed into a reaction tank; the chlorine alkali industry waste water as shown in Table 5 was added into the reaction tank (the addition amount was 28 kg per ton of the reverse osmosis concentrated water), and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 1 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust its pH to 8 with HCl, and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the COD of the reverse osmosis concentrated water was reduced to 240 ppm, and then the reverse osmosis concentrated water was fed into a multi-media filter for filtration. The obtained filtrate was fed into an oxidation tower loaded with 1# catalyst and stayed for 90 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 80 ppm, and the removal rate of COD was 73.3%. Then the filtrate was fed into an activated carbon adsorption tower for adsorption treatment. After adsorption treatment for 1 h, the effluent water had a COD of 38 ppm, a pH of 8, a SiO.sub.2 content of 10 ppm, and a hardness (calculated by CaCO.sub.3) of 290 ppm.

(33) Step (2): The effluent water of the activated carbon adsorption tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 75 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(34) Step (3): The obtained second-stage reverse osmosis product water (COD was 5 ppm, ammonia nitrogen was 0.4 ppm, TDS was 100 ppm, and conductivity was 190 s/cm) was reused as recycling water. The obtained second-stage reverse osmosis concentrated water (COD was 152 ppm, pH was 8.5, SiO.sub.2 content was 49 ppm, hardness (calculated by CaCO.sub.3) was 1188 ppm) was fed into an oxidation unit for continued processing. Specifically, 10 wt % of NaClO solution was added to the obtained second-stage reverse osmosis concentrated water (the addition amount was 3.5 Kg per ton of the second-stage reverse osmosis concentrated water), and the mixed liquid was reacted in the oxidation device for 1 h and then fed into a regulating tank to adjust its pH to 7.5 with HCl. 10 wt % of H.sub.2O.sub.2 was added (the addition amount was 1.12 kg/t of the second-stage reverse osmosis concentrated water) for the reduction of excess NaClO, then the second-stage reverse osmosis concentrated water was fed into a multi-media filter, and then fed into an activated carbon adsorption tower for adsorption treatment of 2 h to obtain effluent water. The effluent water had a COD of 25 ppm, and a COD removal rate of 83.6%, which meets the national standard GB 31571-2015 as shown in Table 2.

Example 6: Treatment of Reverse Osmosis Concentrated Water (2# Catalyst+Chlorine Alkali Industry Waste Water)

(35) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed into a reaction tank; the chlorine alkali industry waste water as shown in Table 5 was added to the reaction tank (the addition amount was 2.9 kg per ton of the reverse osmosis concentrated water), and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 1 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust its pH to 7.5 with HCl, and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the COD of the reverse osmosis concentrated water was reduced to 38 ppm, and then the reverse osmosis concentrated water was filtered by a sand filter apparatus. The obtained filtrate was fed into an oxidation tower loaded with 2# catalyst and stayed for 30 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 20 ppm, the removal rate of COD was 60%, the pH was 7.8, the SiO.sub.2 content was 10 ppm, and the hardness (calculated by CaCO.sub.3) was 62 ppm.

(36) Step (2): The effluent water of the oxidation tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 85 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(37) Step (3): The obtained second-stage reverse osmosis product water (COD was 3 ppm, ammonia nitrogen was 0.1 ppm, TDS was 40 ppm, and conductivity was 70 s/cm) was reused as recycling water. The obtained second-stage reverse osmosis concentrated water (COD was 125 ppm, pH was 8.2, SiO.sub.2 content was 50 ppm, hardness (calculated by CaCO.sub.3) was 389 ppm) was fed into an oxidation unit for continued processing. Specifically, 10 wt % of NaClO solution was added to the obtained second-stage reverse osmosis concentrated water (the addition amount was 2.9 Kg per ton of the second-stage reverse osmosis concentrated water), the mixed liquid was reacted in the oxidation device for 1 h and then fed into a regulating tank to adjust its pH to 8 with HCl. Na.sub.2SO.sub.3 was added (the addition amount was 0.34 kg/t of the second-stage reverse osmosis concentrated water) for the reduction of excess NaClO, then the second-stage reverse osmosis concentrated water was fed into a multi-media filter, and then the filtrate was fed into an activated carbon adsorption tower for adsorption treatment of 2 h to obtain effluent water. The effluent water had a COD of 15 ppm, and a COD removal rate of 88.0%, which meets the national standard GB 31571-2015 as shown in Table 2.

Example 7: Treatment of Reverse Osmosis Concentrated Water (3# Catalyst+Chlorine Alkali Industry Waste Water)

(38) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed into a reaction tank; the chlorine alkali industry waste water as shown in Table 5 was added to the reaction tank (the addition amount was 24 kg per ton of the reverse osmosis concentrated water), and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 0.5 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust its pH to 8.5 with HCl and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the COD of the reverse osmosis concentrated water was reduced to 159 ppm, and then the reverse osmosis concentrated water was filtered by a multi-media filter. The obtained filtrate was fed into an oxidation tower loaded with 3# catalyst and stayed for 60 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 38 ppm, the removal rate of COD was 81.9%, the pH was 8.5, the SiO.sub.2 content was 7 ppm, and the hardness (calculated by CaCO.sub.3) was 150 ppm.

(39) Step (2): The effluent water of the oxidation tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 80 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(40) Step (3): The obtained second-stage reverse osmosis product water (COD was 3 ppm, ammonia nitrogen was 0.2 ppm, TDS was 80 ppm, and conductivity was 170 s/cm) was reused as recycling water. The obtained second-stage reverse osmosis concentrated water (COD was 190 ppm, pH was 8.8, SiO.sub.2 content was 29 ppm, hardness (calculated by CaCO.sub.3) was 760 ppm) was fed into an oxidation unit for continued processing. Specifically, 10 wt % of NaClO solution was added to the obtained second-stage reverse osmosis concentrated water (the addition amount was 4.4 Kg per ton of the second-stage reverse osmosis concentrated water), the mixed liquid was reacted in the oxidation device for 1 h and then fed into a regulating tank to adjust its pH to 6-9 with HCl; and Na.sub.2SO.sub.3 was added (the addition amount was 0.52 kg/t of the second-stage reverse osmosis concentrated water) for the reduction of excess NaClO, then the second-stage reverse osmosis concentrated water was fed into a microfiltration apparatus, and the filtrate was fed into an activated carbon adsorption tower for adsorption treatment of 3 h, to obtain effluent water. The effluent water had a COD of 41 ppm, and a COD removal rate of 78.4%, which meets the national standard GB 31571-2015 as shown in Table 2.

Example 8: Treatment of Reverse Osmosis Concentrated Water (4# Catalyst+Chlorine Alkali Industry Waste Water)

(41) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed into a reaction tank; the chlorine alkali industry waste water as shown in Table 5 was added to the reaction tank (the addition amount was 18 kg per ton of reverse osmosis concentrated water), and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 2 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust its pH to 6 with HCl and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the COD of the reverse osmosis concentrated water was reduced to 123 ppm, and then the reverse osmosis concentrated water was filtered by the multi-media filter; the filtrate was fed into an oxidation tower loaded with 4# catalyst and stayed for 30 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 34 ppm, the removal rate of COD was 78.5%, the pH was 6.5, the SiO.sub.2 content of 5 ppm, and the hardness (calculated by CaCO.sub.3) of 260 ppm.

(42) Step (2): The effluent water of the oxidation tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 80 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(43) Step (3): The obtained second-stage reverse osmosis product water (COD was 2 ppm, ammonia nitrogen was 0.3 ppm, TDS was 80 ppm, and conductivity was 172 s/cm) was reused as recycling water. The obtained second-stage reverse osmosis concentrated water (COD was 147 ppm, pH was 7, SiO.sub.2 content was 25 ppm, hardness (calculated by CaCO.sub.3) was 1640 ppm) was fed into an oxidation unit for continued processing. Specifically, 10 wt % of NaClO solution was added to the obtained second-stage reverse osmosis concentrated water (the addition amount was 3.4 Kg per ton of the second-stage reverse osmosis concentrated water), the mixed liquid was reacted in the oxidation device for 1 h and then fed into a regulating tank to adjust its pH to 6-9 with HCl; and Na.sub.2SO.sub.3 was added (the addition amount was 0.40 kg/t of the second-stage reverse osmosis concentrated water) for the reduction of excess NaClO, and stayed for 1 h; then the the second-stage reverse osmosis concentrated water was fed into a multi-media filter for filtration, and the filtrate was fed into an activated carbon adsorption tower for adsorption treatment of 2 h to obtain effluent water. The effluent water had a COD of 23 ppm and a COD removal rate of 84.4%, which meets the national standard GB 31571-2015 as shown in Table 2.

Example 9: Treatment of Reverse Osmosis Concentrated Water (2# Catalyst+NaClO, Na.SUB.2.Co.SUB.3 .and NaOH)

(44) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed into a reaction tank; 10 wt % of NaClO solution (the addition amount was 0.6 kg per ton of the reverse osmosis concentrated water), 30 wt % of Na.sub.2CO.sub.3 solution (the addition amount was 0.87 kg per ton of reverse osmosis concentrated water) and 48 wt % of NaOH solution (the addition amount was 0.06 kg per ton of reverse osmosis concentrated water) were further added to the reaction tank, and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 1 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust its pH to 7.5 with HCl and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the clear liquid was then filtered by a multi-media filter, and the filtrate was fed into an oxidation tower loaded with 2# catalyst and stayed for 30 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 20 ppm, the removal rate of COD was 60%, the pH was 7.8, the SiO.sub.2 content was 10 ppm, and the hardness (calculated by CaCO.sub.3) was 62 ppm.

(45) Step (2): The effluent water of the oxidation tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 85 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(46) Step (3): The obtained second-stage reverse osmosis product water (COD was 3 ppm, ammonia nitrogen was 0.1 ppm, TDS was 41 ppm, and conductivity was 74 s/cm) was reused as recycling water. The obtained second-stage reverse osmosis concentrated water (COD was 125 ppm, pH was 8.2, SiO.sub.2 content was 50 ppm, hardness (calculated by CaCO.sub.3) was 389 ppm) was fed into an oxidation unit for continued processing. Specifically, 10 wt % of NaClO solution was added to the obtained second-stage reverse osmosis concentrated water (the addition amount was 2.9 Kg per ton of the second-stage reverse osmosis concentrated water), and the mixed liquid was reacted in the oxidation device for 1 h and then was fed into a regulating tank to adjust its pH to 8 with HCl; and Na.sub.2SO.sub.3 was added (the addition amount was 0.34 kg/t of the second-stage reverse osmosis concentrated water) for the reduction of excess NaClO, then the second-stage reverse osmosis concentrated water was fed into a multi-media filter for filtration, and then the filtrate was fed into an activated carbon adsorption tower for adsorption treatment of 2 h to obtain effluent water. The effluent water had a COD of 15 ppm and a COD removal rate of 88.0%, which meets the national standard GB 31571-2015 as shown in Table 2.

Example 10: Treatment of Reverse Osmosis Concentrated Water (4# Catalyst+NaClO, Na.SUB.2.Co.SUB.3 .and NaOH)

(47) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed into the reaction tank; 10 wt % of NaClO solution (the addition amount was 3.6 kg per ton of the reverse osmosis concentrated water), 30 wt % of Na.sub.2CO.sub.3 solution (the addition amount was 5.4 kg per ton of the reverse osmosis concentrated water) and 48 wt % of NaOH solution (the addition amount was 0.375 kg per ton of the reverse osmosis concentrated water) were further added into the reaction tank, and a PAC and PAM solution was added until the occurance of large floccule, mixed and reacted for 2 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust its pH to 6 with HCl and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the COD of the reverse osmosis concentrated water was reduced to 123 ppm, and the reverse osmosis concentrated water was filtered by a multi-media filter, and then the filtrate was fed into an oxidation tower loaded with 4# catalyst and stayed for 30 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 34 ppm, the removal rate of COD was 78.5%, the pH was 6.5, the SiO.sub.2 content was 5 ppm, and the hardness (calculated by CaCO.sub.3) was 260 ppm.

(48) Step (2): The effluent water of the oxidation tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 80 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(49) Step (3): The obtained second-stage reverse osmosis product water (COD was 2 ppm, ammonia nitrogen was 0.3 ppm, TDS was 81 ppm, and conductivity was 174 s/cm) was reused as recycling water. The obtained second-stage reverse osmosis concentrated water (COD was 147 ppm, pH was 7, SiO.sub.2 content was 25 ppm, hardness (calculated by CaCO.sub.3) was 1640 ppm) was fed into an oxidation unit for continued processing. Specifically, 10 wt % of NaClO solution was added to the obtained second-stage reverse osmosis concentrated water (the addition amount was 3.4 Kg per ton of the second-stage reverse osmosis concentrated water), and the mixed liquid was reacted in the oxidation device for 1 h and then fed into a regulating tank to adjust its pH to 6-9 with HCl; and Na.sub.2SO.sub.3 was added (the addition amount was 0.40 kg/t of the second-stage reverse osmosis concentrated water) for the reduction of excess NaClO, and stayed for 1 h, then the second-stage reverse osmosis concentrated water was fed into a multi-media filter for filtration, and then the filtrate was fed into an activated carbon adsorption tower for adsorption treatment of 2 h to obtain effluent water. The effluent water had a COD of 23 ppm and a COD removal rate of 84.4%, which meets the national standard GB 31571-2015 as shown in Table 2.

Example 11: Treatment of Reverse Osmosis Concentrated Water (a Catalyst in CN 104549316 A+Chlorine Alkali Industry Waste Water)

(50) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed into a reaction tank; the chlorine alkali industry waste water as shown in Table 5 (the addition amount was 28 kg per ton of the reverse osmosis concentrated water) was added to the reaction, and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 1 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust the pH to 8 with HCl and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the COD of the reverse osmosis concentrated water was reduced to 240 ppm, and the reverse osmosis concentrated water was filtered by a multi-media filter, then the filtrate was fed into an oxidation tower loaded with the catalyst of Example 1 in CN 104549316 A and stayed for 90 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 112 ppm, the removal rate of COD was 62.7%, and then the water was fed into an activated the active carbon adsorption tower for adsorption treatment, after 2 h of adsorption treatment, the COD of the effluent water is 48 ppm, the pH was 8, the SiO.sub.2 content was 10 ppm, and the hardness (calculated by CaCO.sub.3) was 290 ppm.

(51) Step (2): The effluent water of the activated carbon adsorption tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 75 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(52) Step (3): The obtained second-stage reverse osmosis product water (COD was 5 ppm, ammonia nitrogen was 0.4 ppm, TDS was 100 ppm, and conductivity was 190 s/cm) was reused as recycling water. The obtained second-stage reverse osmosis concentrated water (COD was 205 ppm, pH was 8.5, SiO.sub.2 content was 49 ppm, hardness (calculated by CaCO.sub.3) was 1188 ppm) was fed into an oxidation unit for continued processing. Specifically, 10 wt % of NaClO solution was added to the obtained second-stage reverse osmosis concentrated water (the addition amount was 4.8 Kg per ton of the second-stage reverse osmosis concentrated water), and the mixed liquid was reacted in the oxidation device for 1 h and then fed into a regulating tank to adjust its pH to 7.5 with HCl; and Na.sub.2SO.sub.3 was added (the addition amount was 0.57 kg/t of the second-stage reverse osmosis concentrated water) for the reduction of excess NaClO, and stayed for 2 h, then the second-stage reverse osmosis concentrated water was fed into a multi-media filter for filtration, and then the filtrate was fed into an activated carbon adsorption tower for adsorption treatment of 2 h to obtain effluent water. The effluent water had a COD of 55 ppm, and a COD removal rate of 73.2%, which meets the national standard GB 31571-2015 as shown in Table 2. When the adsorption treatment time of the activated carbon adsorption tower was extended to 3 h, the COD of the obtained effluent water was 49 ppm, and the COD removal rate was 76.1%, which meets national standard GB 31571-2015 as shown in Table 2.

Comparative Example 1: Treatment of Reverse Osmosis Concentrated Water (Fenton Oxidation Process)

(53) The reverse osmosis concentrated water shown in Table 4 was taken and treated by Fenton oxidation process, firstly the reaction pH was adjusted to 3, and 10 wt % of H.sub.2O.sub.2 solution (the addition amount was 6.4 kg per ton of the reverse osmosis concentrated water) and FeSO.sub.4 (the addition amount was 0.57 kg per ton of the reverse osmosis concentrated water) were added thereinto. After reaction for 1 h, the pH was adjusted to 9, and a certain amount of PAC and PAM was added for flocculation and precipitation, then the reverse osmosis concentrated water was filtered by a multi-media filter, and the effluent water had a COD of 172 ppm and a COD removal rate of 42.7%; when the reaction temperature was increased to 50 C., and the reaction time was extended to 4 h, the effluent water had a COD of 148 ppm and a COD removal rate of 50.7%, which was difficult to reach the reverse osmosis water inflow index and the national standard GB 31571-2015 shown in Table 2, thus the subsequent reverse osmosis treatment was failed to be conducted.

Comparative Example 2: Treatment of Reverse Osmosis Concentrated Water (Catalyst of CN 101844828 B+NaClO, Na.SUB.2.Co.SUB.3 .and NaO)

(54) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed to a reaction tank; 10 wt % of NaClO solution (the addition amount was 0.58 kg per ton of the reverse osmosis concentrated water), 30 wt % of Na.sub.2CO.sub.3 solution (the addition amount was 0.87 kg per ton of the reverse osmosis concentrated water) and 48 wt % of NaOH solution (the addition amount was 0.06 kg per ton of the reverse osmosis concentrated water) were added to the reaction tank, and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 1 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid was fed into a clarification tank to adjust its pH to 7.5 with HCl and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the liquid was then filtered by a multi-media filter, and the filtrate was fed into an oxidation tower loaded with the catalyst of Example 1 in CN 101844828 B and stayed for 30 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 29 ppm, the removal rate of COD was 42%, the pH was 7.8, the SiO.sub.2 content was 10 ppm, and hardness (calculated by CaCO.sub.3) was 62 ppm.

(55) Step (2): The effluent water of the oxidation tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 85 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(56) Step (3): The obtained second-stage reverse osmosis product water (COD was 3 ppm) was reused as recycling water, and the obtained second-stage reverse osmosis concentrated water (COD was 188 ppm) was treated by Fenton oxidation process. Specifically, 10 wt % of H.sub.2O.sub.2 solution (the addition amount was 4.0 kg per ton of the second-stage reverse osmosis concentrated water) and FeSO.sub.4 (the addition amount was 0.36 kg per ton of the second-stage reverse osmosis concentrated water) were added to the second-stage reverse osmosis concentrated water. After reaction for 1 h, the pH was adjusted to 9 and PAC and PAM were added for flocculation and precipitation. After filtration by a multi-media filter, the COD of effluent water was 128 ppm, and the COD removal rate was 32.0%; when the reaction temperature was increased to 50 C., and the reaction time was extended to 4 h, the effluent water had a COD of 101 ppm and a COD removal rate of 46.3%, which was difficult to meet the national standard GB 31571-2015 as shown in Table 2.

Comparative Example 3: Treatment of Reverse Osmosis Concentrated Water (Catalyst of CN 104549316 A+Chlorine Alkali Industry Waste Water)

(57) Step (1): The reverse osmosis concentrated water shown in Table 4 was taken and adjusted to pH of 11 with NaOH in a regulating tank, then fed to a reaction tank; the chlorine alkali industry waste water as shown in Table 5 (the addition amount was 18 kg per ton of reverse osmosis concentrated water) was added to the reaction tank, and a PAC and PAM solution was added until the appearance of large floccule, mixed and reacted for 2 h. After the reaction, the precipitation was filtered by a plate and frame filter press, and the most of solid waste was CaCO.sub.3 and Mg(OH).sub.2, which can be used as a raw material for building materials. The clear liquid obtained after filtration was fed into a clarification tank to adjust its pH to 6 with HCl and stayed herein for 1 h. After the above sodium hypochlorite oxidation and the process of reducing hardness and silicon, the COD of the reverse osmosis concentrated water was reduced to 123 ppm, and the reverse osmosis concentrated water was then filtered by a multi-media filter, and the filtrate was fed into an oxidation tower loaded with the catalyst of Example 1 in CN 104549316 A and stayed for 30 min. After the above catalytic oxidation reaction, the COD thereof was reduced to 49 ppm, the removal rate of COD was 68.9%, the pH was 6.5, the SiO.sub.2 content was 5 ppm, and the hardness (calculated by CaCO.sub.3) was 260 ppm.

(58) Step (2): The effluent water of the oxidation tower was subjected to a secondary filtration by a security filter, and the obtained filtrate was fed into a roll reverse osmosis membrane module for reverse osmosis treatment; the water recovery rate was 80 wt %, and second-stage reverse osmosis product water and second-stage reverse osmosis concentrated water were obtained.

(59) Step (3): The obtained second-stage reverse osmosis product water (COD was 3 ppm, ammonia nitrogen was 0.2 ppm, TDS was 80 ppm, conductivity was 170 s/cm) was reused as recycling water, and the obtained second-stage reverse osmosis concentrated water (COD was 247 ppm) was treated by Fenton oxidation process. Specifically, 10 wt % of H.sub.2O.sub.2 solution (the addition amount was 5.2 kg per ton of the second-stage reverse osmosis concentrated water) and FeSO.sub.4 (the addition amount was 0.47 kg per ton of the second-stage reverse osmosis concentrated water) were added to the second-stage reverse osmosis concentrated water. After reaction for 1 h, the pH was adjusted to 9 and PAC and PAM were added for flocculation and precipitation. After filtration by a multi-media filter, the COD of the effluent water was 153 ppm, and the COD removal rate was 38.0%; when the reaction temperature was increased to 50 C., and the reaction time was extended to 4 h, the effluent water had a COD of 127 ppm and a COD removal rate of 48.6%, which was difficult to meet the national standard GB 31571-2015 as shown in Table 2.

(60) Comparing Examples 5-11 with Comparative Examples 1-3, it can be known that:

(61) 1. Through the treating method of the reverse osmosis concentrated water of the present invention, such as the treatments of steps (1), (2) and (3), the organics and hardness ions in the reverse osmosis concentrated water can be removed by using a precipitant and an oxidant; and by combining with the subsequent reverse osmosis treatment, not only 75-85 wt % of the water (second-stage reverse osmosis product water) can be recovered, but also the overall utilization rate of water is improved. Meanwhile, the subsequent reverse osmosis treatment allows the remaining water accounting for a small amount of the water (second-stage reverse osmosis product water) to meet the requirements of GB 31571-2015 in Table 2 and then is discharged as effluent water. Compared with the treatment methods of the comparative examples, the method of the present application is environment friendly, has low economic input, simple and easy to operate;

(62) 2. Comparing using the chlorine alkali industry waste water containing NaClO, NaOH and Na.sub.2CO.sub.3 to perform the oxidation and precipitation treatment on the reverse osmosis concentrated water with using NaClO, NaOH and Na.sub.2CO.sub.3 directly to perform the oxidation and precipitation treatment on the reverse osmosis concentrated water, there is no difference between the treatment results, which indicates that: this application can fully utilize the oxidizability of a small amount of sodium hypochlorite containing in the chlorine alkali industry waste water to achieve the treatment of refractory organic pollutants in the reverse osmosis concentrated water, make full use of the precipitation reaction of NaOH and Na.sub.2CO.sub.3 contained in the chlorine alkali industry waste water, achieve the removal of Ca.sup.2+, Mg.sup.2+, SiO.sub.2 and the like in the reverse osmosis concentrated water, and achieve the purpose of treating waste by waste. In the actual industrial process, the reverse osmosis concentrated water can be treated with the chlorine alkali industry waste water containing oxidant and precipitant, which saves the cost of chemicals, and also saves the expense of agents and cost of treating chlorine alkali industry waste water compared with directly using an oxidant and a precipitant;

(63) 3. Compared with the catalyst in the prior art, the catalyst of the present invention has a higher catalytic oxidation performance, thereby effectively degrades the refractory organic pollutants in the reverse osmosis concentrated water; the treatment effect on the reverse osmosis concentrated water is good, and the COD removal rate is high.

(64) For the catalysts having the same components and contents thereof, compared with a pure spherical aluminum oxide carrier, the treatment effect on the reverse osmosis concentrated water is better and the COD removal rate is higher when the carrier was a cerium modified aluminum oxide carrier.

(65) Specifically, comparing Examples 5 and 11 to Comparative Example 1, it can be seen that:

(66) Compared with the prior art of Comparative Example 1, the method of the present invention has a better treatment effect on reverse osmosis concentrated water and a higher COD removal rate.

(67) The catalytic oxidation of the oxidant with the catalyst of the invention and the catalyst of the prior art can both achieve the object of the present invention, and the treatment effect on the reverse osmosis concentrated water was good and the COD removal rate was high.

(68) However, compared with using a catalyst in the prior art, using the catalyst of the present invention can improve the treatment effect on the reverse osmosis concentrated water and increase the COD removal rate.

(69) Comparing Examples 5 and 9 with Comparative Example 2, it can be seen that:

(70) In step (1), comparing using the chlorine alkali industry waste water containing NaClO, NaOH and Na.sub.2CO.sub.3 to perform the oxidation and precipitation treatment on the reverse osmosis concentrated water with using NaClO, NaOH and Na.sub.2CO.sub.3 directly to perform the oxidation and precipitation treatment on the reverse osmosis concentrated water, there is no difference between the treatment results. However, it can achieve the purpose of treating waste by waste through treatment to organic waste water such as reverse osmosis concentrated water and the like with the chlorine alkali industry waste water containing NaClO, NaOH and Na.sub.2CO.sub.3.

(71) In step (3), compared with Fenton oxidation treatment used in Comparative Example 2, the method of the present invention uses the oxidant such as NaClO, the reductant such as Na.sub.2SO.sub.3, and the activated carbon adsorption and the like for treatment, and the treatment effect on the second-stage reverse osmosis concentrated water is better and the COD removal rate is higher.

(72) Comparing Example 8 with Example 10, it can be seen that:

(73) In step (1), comparing using the chlorine alkali industry waste water containing NaClO, NaOH and Na.sub.2CO.sub.3 to perform the oxidation and precipitation treatment on the reverse osmosis concentrated water with using NaClO, NaOH and Na.sub.2CO.sub.3 directly to perform the oxidation and precipitation treatment on the reverse osmosis concentrated water, there is no difference between the treatment results. However, it can achieve the purpose of treating waste by waste through treatment to organic waste water such as reverse osmosis concentrated water and the like with the chlorine alkali industry waste water containing NaClO, NaOH and Na.sub.2CO.sub.3.

(74) Comparing Example 8 with Comparative Example 3, it can be seen that:

(75) In step (3), compared with Fenton oxidation treatment used in Comparative Example 3, the method of the present invention uses the oxidant such as NaClO, the reductant such as Na.sub.2SO.sub.3, and the activated carbon adsorption and the like for treatment, and the treatment effect on the second-stage reverse osmosis concentrated water is better and the COD removal rate is higher.