TREATMENT METHOD OF WASTEWATER CONTAINING FERRICYANIDE COMPLEX AND OXALATE

Abstract

Provided is a treatment method of waste water containing ferricyanide complex and oxalate, comprising under the condition of weak acidity to weak alkalinity, firstly adding an appropriate amount of divalent manganese ions to make the divalent manganese ions combined with ferrocyanide ions and part of oxalate ions in wastewater to form a mixed slag mainly composed of manganese ferrocyanide to achieve the purpose of removing most of the cyanide and a small amount of organic substance; adding excess divalent manganese ions to the first filtrate to make the divalent manganese ions fully combined with the oxalate in the wastewater to achieve the purpose of removing organic substance, and then adding an appropriate amount of alkali to the second filtrate to form precipitation to achieve the purpose of recovering manganese; then adding an appropriate amount of ferrous salt to achieve the purpose of removing the remaining cyanide and organic substance.

Claims

1. A treatment method of wastewater containing ferricyanide complex and oxalate, comprising the following steps S1: adjusting the pH of the wastewater to 5-9, then adding divalent manganese salt A to the wastewater, stirring for reaction, and adding flocculant A cationic polyacrylamide, and leaving the mixture to stand for settling, and performing solid-liquid separation to obtain a first filtrate and a manganese(II) hexacyanoferrate(II)-based mixed residue; wherein the wastewater contains ferricyanide complex and oxalate, and the mass of the divalent manganese ions in the added divalent manganese salt A is 5-30 times of the mass of the total cyanide in the wastewater; S2: adding divalent manganese salt B to the first filtrate, stirring for reaction, and adding flocculant A cationic polyacrylamide, and leaving the mixture to stand for settling, and performing solid-liquid separation to obtain a second filtrate and a filter residue, and performing a rinsing process on the filter residue to recover manganese oxalate; wherein the mass of the divalent manganese ions in the added divalent manganese salt B is 1.4-7 times of COD in the wastewater; S3: adding alkali to the second filtrate to adjust the pH of the second filtrate to 11-13, stirring for reaction, and adding flocculant B anionic polyacrylamide, and leaving the mixture to stand for settling, and performing solid-liquid separation to obtain a third filtrate and a filter residue, and performing a rinsing process on the filter residue to recover manganese resources; S4: adjusting the pH of the third filtrate to 5-8, then adding ferrous salt, stirring for reaction, and adding flocculant A cationic polyacrylamide, and leaving the mixture to stand for settling, and performing solid-liquid separation to obtain a fourth filtrate; wherein the addition amount of the ferrous salt is 5-30 g/L of the third filtrate; S5: adding alkali to the fourth filtrate to adjust the pH of the fourth filtrate to 11-13, stirring for reaction, and adding flocculant B anionic polyacrylamide, and performing solid-liquid separation to obtain a fifth filtrate.

2. The treatment method according to claim 1, wherein in step S1, the content of total cyanide in the wastewater is 100-2000 mg/L, and the content of COD is 2000-10000 mg/L.

3. The treatment method according to claim 1, wherein the divalent manganese salt A and the divalent manganese salt B are independently at least one of manganese sulfate, manganese chloride or manganese nitrate.

4. The treatment method according to claim 1, wherein the flocculant A is a cationic polyacrylamide solution with a mass concentration of 0.5-1.5; the flocculant B is an anionic polyacrylamide solution with a mass concentration of 0.5-1.5.

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. (canceled)

10. The treatment method according to claim 1, wherein in step S5, the content of total cyanide in the fifth filtrate is ?0.5 mg/L, the content of COD is ?500 mg/L, and the content of Mn.sup.2+?0.5 mg/L.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0033] The present disclosure will be further described below in conjunction with the drawings and embodiments, wherein:

[0034] FIG. 1 is a process flow chart of the present disclosure.

DETAILED DESCRIPTION

[0035] The concept of the present disclosure and the technical effects produced by the present disclosure will be clearly and completely described below with reference to the embodiments, so as to make the purpose, characteristics and effects of the present disclosure fully understood. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of the present disclosure, other embodiments obtained by those skilled in the art without creative efforts are all within the protection scope of the present disclosure.

Example 1

[0036] A treatment method of wastewater containing ferricyanide complex and oxalate, with reference to FIG. 1, the specific process is: [0037] (1) 400 mL of wastewater containing ferricyanide complex and oxalate was taken and added with 30% dilute sulfuric acid to adjust the pH of the wastewater to 7-8; [0038] (2) Then 7 g of manganese sulfate monohydrate was taken and stirred to react for 60 min, and then added with 3 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a first filtrate; [0039] (3) 12 g manganese sulfate monohydrate was added to the first filtrate and stirred to react for 60 min, then added with 2 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a second filtrate. The precipitate obtained by separation was rinsed five times to recover the manganese oxalate resource; [0040] (4) 10 mL of 30% sodium hydroxide solution was added to the second filtrate to stabilize the pH of the second filtrate at 12-13 and stirred to react for 30 min, and then added with 2 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a third filtrate. The precipitate obtained by separation was rinsed five times to recover the manganese resource; [0041] (5) 30% dilute sulfuric acid was added to the third filtrate to adjust the pH of the wastewater to 6-7, and 350 mL of the third filtrate after the value adjustment was taken and added with 7 g ferrous sulfate heptahydrate, stirred to react for 60 min, and then added with 1 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 minutes, left to stand for settling, and solid-liquid separated to obtain a fourth filtrate; [0042] (6) 3.5 mL of 30% sodium hydroxide solution was added to the fourth filtrate to stabilize the pH of the fourth filtrate at 12-13, stirred to react for 30 minutes, and then added with 1 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a fifth filtrate. 30% dilute sulfuric acid was added to the fifth filtrate to adjust the pH of the wastewater to 7.5, and then the wastewater could be discharged. The main components of the wastewater before and after treatment are shown in Table 1.

TABLE-US-00001 TABLE 1 Main components of wastewater before and after treatment in Example 1 Water sample CN.sub.T (mg/L) COD (mg/L) Mn.sup.2+ (mg/L) pH Before treatment 499.93 5118.00 80.55 9.7 The first filtrate 6.30 4620.00 2886.00 7.6 The second filtrate 5.46 1804.00 1938.50 7.3 After treatment 0.20 251.50 0.0075 7.5

[0043] Table 1 shows that the cyanide of the first filtrate has been mostly removed, while the COD content is still high, indicating that at a specific pH, with addition of an appropriate amount of divalent manganese salt, the ferrocyanide in the system precipitates first, but only a small amount of oxalate precipitates. In addition, the content of COD in the second filtrate is also related to the content of Mn in the solution.

Example 2

[0044] A treatment method of wastewater containing ferricyanide complex and oxalate, the specific process is: [0045] (1) 400 mL of wastewater containing ferricyanide complex and oxalate was taken and added with 30% dilute sulfuric acid to adjust the pH of the wastewater to 6-7; [0046] (2) Then 8 g of manganese sulfate monohydrate was taken and stirred to react for 60 min, and then added with 2 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a first filtrate; [0047] (3) 12 g manganese sulfate monohydrate was added to the first filtrate and stirred to react for 60 min, then added with 2 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a second filtrate. The precipitate obtained by separation was rinsed five times to recover the manganese oxalate resource; [0048] (4) 10 mL of 30% sodium hydroxide solution was added to the second filtrate to stabilize the pH of the second filtrate at 12-13 and stirred to react for 30 min, and then added with 1 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a third filtrate. The precipitate obtained by separation was rinsed five times to recover the manganese resource; [0049] (5) 30% dilute sulfuric acid was added to the third filtrate to adjust the pH of the wastewater to 6-7, and 350 mL of the third filtrate after the value adjustment was taken and added with 1.75 g ferrous sulfate heptahydrate, stirred to react for 60 min, and then added with 1 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 minutes, left to stand for settling, and solid-liquid separated to obtain a fourth filtrate; [0050] (6) 3.5 mL of 30% sodium hydroxide solution was added to the fourth filtrate to stabilize the pH of the fourth filtrate at 12-13, stirred to react for 30 minutes, and then added with 1 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a fifth filtrate. 30% dilute sulfuric acid was added to the fifth filtrate to adjust the pH of the wastewater to 7.3, and then the wastewater could be discharged. The main components of the wastewater before and after treatment are shown in Table 2.

TABLE-US-00002 TABLE 2 Main components of wastewater before and after treatment in Example 2 Water sample CN.sub.T (mg/L) COD (mg/L) Mn.sup.2+ (mg/L) pH Before treatment 1055.00 5940.00 237.90 9.0 The first filtrate 7.20 5020.00 2369.00 6.5 The second filtrate 6.44 1544.00 1732.25 6.3 After treatment 0.40 452.90 0.0070 7.3

Example 3

[0051] A treatment method of wastewater containing ferricyanide complex and oxalate, the specific process is: [0052] (1) 400 mL of wastewater containing ferricyanide complex and oxalate was taken and added with 30% dilute sulfuric acid to adjust the pH of the wastewater to 7-8; [0053] (2) Then 8 g of manganese sulfate monohydrate was taken and stirred to react for 60 min, and then added with 3 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a first filtrate; [0054] (3) 13 g manganese sulfate monohydrate was added to the first filtrate and stirred to react for 60 min, then added with 2 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a second filtrate. The precipitate obtained by separation was rinsed five times to recover the manganese oxalate resource; [0055] (4) 10 mL of 30% sodium hydroxide solution was added to the second filtrate to stabilize the pH of the second filtrate at 12-13 and stirred to react for 30 min, and then added with 2 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a third filtrate. The precipitate obtained by separation was rinsed five times to recover the manganese resource; [0056] (5) 30% dilute sulfuric acid was added to the third filtrate to adjust the pH of the wastewater to 6-7, and 350 mL of the third filtrate after the value adjustment was taken and added with 3.5 g ferrous sulfate heptahydrate, stirred to react for 60 min, and then added with 1 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a fourth filtrate; [0057] (6) 3.5 mL of 30% sodium hydroxide solution was added to the fourth filtrate to stabilize the pH of the fourth filtrate at 12-13, stirred to react for 30 min, and then added with 1 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a fifth filtrate. 30% dilute sulfuric acid was added to the fifth filtrate to adjust the pH of the wastewater to 7.0, and then the wastewater could be discharged. The main components of the wastewater before and after treatment are shown in Table 3.

TABLE-US-00003 TABLE 3 Main components of wastewater before and after treatment in Example 3 Water sample CN.sub.T (mg/L) COD (mg/L) Mn.sup.2+ (mg/L) pH Before treatment 266.63 4088.00 77.43 8.8 The first filtrate 6.50 3528.00 2579.00 7.2 The second filtrate 4.95 2144.10 2332.50 7.1 After treatment 0.1 163.20 0.0054 7.0

Comparative Example 1

[0058] A treatment method of wastewater containing ferricyanide complex and oxalate, which is different from Example 1 in that the addition amount of ferrous salt was less than 5 g/L. The specific process is: [0059] (1) 400 mL of wastewater containing ferricyanide complex and oxalate was taken and added with 30% dilute sulfuric acid to adjust the pH of the wastewater to 7-8; [0060] (2) Then 7 g of manganese sulfate monohydrate was taken and stirred to react for 60 min, and then added with 3 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a first filtrate; [0061] (3) 12 g manganese sulfate monohydrate was added to the first filtrate and stirred to react for 60 min, then added with 2 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a second filtrate. The precipitate obtained by separation was rinsed five times to recover the manganese oxalate resource; [0062] (4) 10 mL of 30% sodium hydroxide solution was added to the second filtrate to stabilize the pH of the second filtrate at 12-13 and stirred to react for 30 min, and then added with 2 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a third filtrate; [0063] (5) 30% dilute sulfuric acid was added to the third filtrate to adjust the pH of the wastewater to 6-7, and 350 mL of the third filtrate after the value adjustment was taken and added with 0.7 g ferrous sulfate heptahydrate, stirred to react for 60 min, and then added with 1 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a fourth filtrate; [0064] (6) 3.5 mL of 30% sodium hydroxide solution was added to the fourth filtrate to stabilize the pH of the fourth filtrate at 12-13, stirred to react for 30 min, and then added with 1 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a fifth filtrate. 30% dilute sulfuric acid was added to the fifth filtrate to adjust the pH of the wastewater to 7.3, and then the wastewater could be discharged. The main components of the wastewater before and after treatment are shown in Table 4.

TABLE-US-00004 TABLE 4 Main components of wastewater before and after treatment in Comparative example 1 Water sample CN.sub.T (mg/L) COD (mg/L) Mn.sup.2+ (mg/L) pH Before treatment 499.93 5118.00 80.55 9.7 The first filtrate 6.30 4620.00 2886.00 7.6 The second filtrate 5.46 1804.00 1938.50 7.3 After treatment 1.44 273.50 0.0072 7.3

[0065] In Comparative example 1, the addition amount of ferrous salt was less than 5 g/L, and the total cyanide concentration in the wastewater could not be treated to meet the third-level standard discharge requirements stipulated in the Integrated Wastewater Discharge Standard (GB8978-1996).

Comparative Example 2

[0066] A treatment method of wastewater containing ferricyanide complex and oxalate, which is different from Example 2 in that there was no step (3). The specific process is: [0067] (1) 400 mL of wastewater containing ferricyanide complex and oxalate was taken and added with 30% dilute sulfuric acid to adjust the pH of the wastewater to 6-7; [0068] (2) Then 8 g of manganese sulfate monohydrate was taken and stirred to react for 60 min, and then added with 3 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a first filtrate; [0069] (3) 10 mL of 30% sodium hydroxide solution was added to the first filtrate to stabilize the pH of the first filtrate at 12-13 and stirred to react for 30 min, and then added with 2 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a second filtrate; [0070] (4) 30% dilute sulfuric acid was added to the second filtrate to adjust the pH of the wastewater to 6-7, and 350 mL of the second filtrate after the value adjustment was taken and added with 1.75 g ferrous sulfate heptahydrate, stirred to react for 60 min, and then added with 1 mL of cationic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, left to stand for settling, and solid-liquid separated to obtain a third filtrate; [0071] (5) 3.5 mL of 30% sodium hydroxide solution was added to the third filtrate to stabilize the pH of the third filtrate at 12-13, stirred to react for 30 min, and then added with 1 mL of anionic polyacrylamide solution with a mass concentration of 1. The mixture was stirred for 5 min, and solid-liquid separated to obtain a fourth filtrate. 30% dilute sulfuric acid was added to the fourth filtrate to adjust the pH of the wastewater to 7.3, and then the wastewater could be discharged. The main components of the wastewater before and after treatment are shown in Table 5.

TABLE-US-00005 TABLE 5 Main components of wastewater before and after treatment in Comparative example 2 Water sample CN.sub.T (mg/L) COD (mg/L) Mn.sup.2+ (mg/L) pH Before treatment 1055.00 5940 111.9 9.0 The first filtrate 7.20 5020.00 2369.00 6.5 After treatment 4.75 3515 0.0065 7.3

[0072] In Comparative example 2, manganese sulfate monohydrate was not added for the second time, and the concentration of total cyanide and COD in the wastewater could not be treated to meet the third-level standard discharge requirements stipulated in the Integrated Wastewater Discharge Standard (GB8978-1996).

[0073] The embodiments of the present disclosure have been described in detail above in conjunction with the drawings, but the present disclosure is not limited to the above-mentioned embodiments, Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can also be made without departing from the spirit of the present disclosure. Furthermore, the embodiments and the features in the embodiments of the present disclosure may be combined with each other without conflict.