CN105776765A - Cyanide-containing wastewater treatment method - Google Patents

Abstract

The invention discloses a cyanide-containing wastewater treatment method. The cyanide-containing wastewater treatment method includes steps of S10, sequentially acidizing and stripping the cyanide-containing wastewater to obtain gaseous phase and liquid phase; S20, absorbing the gaseous phase with absorption liquid to recycle to obtain residual liquid; S30, coagulating and depositing the liquid phase while performing the step 20; S40, biochemically treating coagulated and deposited wastewater. Through acidizing, stripping, coagulating and deposition, and biochemical treatment of the cyanide-containing wastewater generated by electroplating, pollutants such as COD, nitrogen, phosphorous, cyanide and heavy metal in the effluent can be discharged under certain standard. Meanwhile, HCN stripped can be recycled, waste and environment pollution can be avoided, and treatment cost of the cyanide-containing wastewater is reduced. Compared with a conventional treatment method of the cyanide-containing wastewater, the cyanide-containing wastewater treatment method is easier to industrial application.

Description

Cyanide-containing wastewater treatment method

technical field

The invention belongs to the technical field of wastewater treatment, and in particular relates to a method for treating cyanide-containing wastewater.

Background technique

Cyanide plating is one of the commonly used plating methods, mainly used for zinc plating, lead plating, cadmium plating, copper plating, silver plating, and gold plating. According to the formulations of various cyanide plating solutions, in addition to highly toxic free cyanide, there are complex ions such as copper cyanide, cadmium cyanide, silver cyanide, and zinc cyanide in the cyanide-containing wastewater generated during the cyanide plating process. Therefore, after breaking cyanide, heavy metal ions will also enter the wastewater. Therefore, the treatment of heavy metal ions should also be included in the treatment of cyanide-containing wastewater. However, cyanide cannot be processed by conventional methods such as precipitation, and must be decomposed into C and N to become non-toxic products.

The treatment of cyanide-containing wastewater has relatively mature experience in China. There are many traditional cyanide-containing wastewater treatment methods, such as electrolytic oxidation, activated carbon adsorption, ion exchange, ozone and alkaline chlorination. Among them, the electrolytic oxidation method adopts the condition that the pH value is greater than 7, CN ^- is oxidized on the anode to generate CNO, CO ₂ , N ₂ , and at the same time Cl ^- is oxidized to Cl ₂ , and Cl enters the solution to generate HClO, which strengthens the Oxidation of oxygen; precipitation of heavy metals on the cathode; the disadvantages of this method are low current efficiency, high power consumption, high cost, and difficult discharge of waste water. The activated carbon adsorption method is that oxygen and water on the surface of activated carbon generate hydrogen peroxide, and then under the action of copper salt, cyanide is decomposed by hydrogen peroxide; this method has high processing costs and is difficult for industrial application. The disadvantage of the ion exchange method is that various resins are relatively expensive, the operation is complicated, and it is difficult for industrial application. The ozone oxidation method is suitable for treating low-concentration cyanide-containing wastewater. Under the condition of pH 11-12, ozone oxidizes cyanide to generate nitrogen and bicarbonate; this method cannot effectively remove copper-cyanide complexes in wastewater, etc. The power consumption of the method is large, the processing cost is high, and the application prospect is not great. Alkaline chlorination is a relatively mature method for destroying cyanide in wastewater, and it is also the mainstream treatment method for cyanide-containing wastewater in domestic electroplating wastewater. The principle is to use chlorine gas or liquid chlorine or bleaching powder to oxidize cyanide in wastewater into carbon dioxide and nitrogen. and other non-toxic substances; this method currently has the problems of not being able to better remove the complexes in the wastewater, resulting in the inability of the wastewater to be discharged stably and up to the standard.

To sum up, the traditional cyanide-containing wastewater treatment methods have the disadvantages that the effluent is difficult to meet the full factor standard or the treatment cost is high, and it is difficult to apply industrially.

Contents of the invention

The purpose of the present invention is to provide a method for treating cyanide-containing wastewater, which can achieve full-factor compliance of the effluent and reduce the cost of wastewater treatment.

For reaching this purpose, the present invention adopts following technical scheme:

A method for treating cyanide-containing wastewater, comprising the steps of:

S10, sequentially performing acidification treatment and stripping treatment on the cyanide-containing wastewater to obtain a gas phase and a liquid phase;

S20. Using an absorption liquid to absorb the gas phase for recycling to obtain an absorption raffinate;

S30, performing coagulation and sedimentation treatment on the liquid phase while performing the step S20;

S40, performing biochemical treatment on the wastewater after the coagulation and sedimentation treatment.

In the present invention, the cyanide-containing wastewater is produced after electroplating, which contains a large amount of cyanide, such as NaCN, Pb(CN) ₄ ^2- , Zn(CN) ₄ ^2- , Cu(CN) ₄ ^2- , Fe(CN) ) ₆ ^4- , Cu(CN) ₃ ^2- , Ag(CN) ₂ ^- , Ni(CN) ₄ ^2- , etc., the present invention can neutralize the alkali in the wastewater by acid by acidifying the cyanide-containing wastewater , to hydrolyze cyanide to produce HCN.

The wastewater after acidification treatment contains a large amount of HCN. After the blow-off treatment, HCN is easily blown out from the wastewater liquid under the action of air, so that the hydrolysis reaction of cyanide in the cyanide-containing wastewater proceeds in the direction of generating HCN, so that the hydrolysis The reaction tends to be balanced, thereby accelerating the hydrolysis reaction rate of cyanide.

The waste water after the acidification treatment is blown off and separated from the gas and liquid to obtain a gas phase and a liquid phase. The gas phase, i.e. HCN, can be absorbed by using the absorbing liquid ^to recycle CN-. On the one hand, resource waste can be avoided. Save energy, on the other hand avoid polluting the environment.

In the present invention, step S20 is carried out in the absorption tower, and the gas containing HCN that blows off the tower comes out, enters by the tower bottom of the absorption tower, and the absorption liquid that absorbs this HCN gas is housed at the bottom of the tower, adopts circulation pump to pump the absorption liquid To the upper and middle parts of the absorption tower, the gas and liquid are contacted in countercurrent through the spraying device, so that the absorption liquid can fully absorb the HCN gas.

In step S30, coagulation and sedimentation treatment is performed on the liquid phase obtained after the stripping treatment, so as to remove heavy metals in the liquid phase. After the sediment (sludge) is formed, the sludge is dehydrated and treated in an environmentally friendly manner, and the sedimented wastewater is biochemically treated so that the pollutants such as COD, nitrogen, phosphorus, a small amount of cyanide and heavy metals in the wastewater can be discharged up to the standard.

The traditional cyanide-containing wastewater treatment method is to perform Fenton reaction treatment on the liquid phase after stripping, and then carry out flocculation and sedimentation treatment, but the treatment method of the present invention does not need to carry out Fenton reaction treatment, and the stripping treatment is directly carried out coagulation and precipitation It only needs to be treated, and the wastewater treatment steps are simpler, and the effluent can achieve full factor compliance, and the treatment effect is better.

In the present invention, as shown in Figure 1, the cyanide-containing wastewater is pumped to the acidification reaction tank by the wastewater regulating tank, and then enters the stripping tower, the coagulation sedimentation tank, the biochemical treatment system successively, and the HCN gas produced in the stripping tower It flows through the absorption tower for resource recycling, and if necessary, re-absorbs the HCN gas in the absorption raffinate. Among them, pH meters are installed in the acidification reaction tanks, and the amount of non-oxidizing acid added and its flow rate are adjusted in real time according to the pH value of the cyanide-containing wastewater in the acidification reaction tanks.

In the present invention, acidification, stripping, coagulation precipitation, and biochemical treatment are carried out sequentially on the cyanide-containing wastewater generated by electroplating, so that the pollutants such as COD, nitrogen, phosphorus, a small amount of cyanide, and heavy metals in the final effluent can be discharged up to the standard, and at the same time, the blown The HCN produced after deprocessing can be recycled, which can avoid resource waste and environmental pollution, and reduce the treatment cost of cyanide-containing wastewater. Compared with the traditional cyanide-containing wastewater treatment method, the cyanide-containing wastewater treatment method of the present invention is easier for industrial application.

In the step S30, first adjust the pH value of the liquid phase to a set value of 8-10, such as 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2 , 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9 or 10, then add coagulant and flocculant for coagulation and sedimentation treatment. The pH value of the liquid phase in this scheme is determined according to the properties and concentrations of heavy metals in the wastewater. When the wastewater contains nickel ions, in order to ensure that the nickel ions are discharged up to the standard, the pH setting value is 9.6-10, such as 9.6, 9.7, 9.8, 9.9 or 10, preferably 10; when the liquid phase contains zinc ions and other heavy metals, the pH setting value is 8.7 to 9.3, such as 8.7, 8.8, 8.9, 9, 9.1, 9.2 or 9.3, preferably 9, but it needs Carry out two-stage precipitation, that is, first control the pH value at a set value of 8 to 8.4, such as 8, 8.1, 8.2, 8.3 or 8.4, preferably 8, precipitate to remove zinc, and then adjust the pH value to a set value of 9, to remove other heavy metals.

In the present invention, the pH setting value is 8-10, and the pH value is a specific value during the pH adjustment process of the liquid phase.

As another solution of the present invention, as shown in FIG. 2 , the liquid phase obtained in step S10 is subjected to acidification treatment and blow-off treatment again, so as to improve the blow-off effect and increase the recycling rate of resources.

In the present invention, a coagulant and a flocculant are added in the coagulation-sedimentation treatment, which are respectively PAC (polyaluminum chloride) and PAM (polyacrylamide). Adjustment.

As yet another solution of the present invention, if other indicators do not meet the standards, the liquid phase obtained in the step S10 needs to be processed several times according to the steps S10, S20, and S30. Repeat steps S10, S20, and S30, and then proceed to step S40, that is, directly pump the liquid phase after the stripping treatment into another acidification reaction tank for acidification treatment again, and then pump it into another stripping tower for stripping treatment, and then carry out absorption and precipitation treatment in another absorption tower and sedimentation tank, and finally carry out biochemical treatment, as shown in Figure 3 (the specific steps will not be repeated), so that all factors of the effluent can reach the standard, ^and the recovery of CN- Utilization is maximized.

As a more specific solution of the present invention, the step S10 includes the following steps:

S10a: adding a non-oxidizing acid to the cyanide-containing wastewater, and adjusting its pH value to 1-3, so as to hydrolyze the cyanide in the cyanide-containing wastewater;

S10b: The acidified waste water containing cyanide is introduced from the top of the stripping tower, and air is blown in from the bottom of the tower by a blower, so as to blow out the gas phase through the air.

In step S10a, the pH value of the cyanide-containing wastewater is adjusted to 1-3, such as 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.2, 2.5, 2.7 or 2.9, using a non-oxidizing acid , causing a series of chemical reactions to occur in cyanide-containing wastewater. The specific reaction equation is as follows:

OH ^- +H ⁺ →H ₂ O

NaCN+H ⁺ ＝HCN+Na ⁺

Pb(CN) ₄ ^2- +4H ⁺ ＝4HCN+Pb ²⁺

Zn(CN) ₄ ^2- +4H ⁺ ＝4HCN+Zn ²⁺

Cu(CN) ₄ ^2- +2H ⁺ ＝2HCN+CuCN↓(gray white)

2Pb ²⁺ +Fe(CN) ₆ ^4- ＝Pb ₂ Fe(CN) ₆ ↓(gray white)

2Zn ²⁺ +Fe(CN) ₆ ^4- ＝Zn ₂ Fe(CN) ₆ ↓(gray white)

CuCN+SCN ^- +H ⁺ ＝HCN+CuSCN↓(gray white)

4Cu(CN) ₃ ^2- +13H ⁺ +Fe(CN) ₆ ^4- ＝12HCN+Cu ₄ Fe(CN) ₆ ↓(light red)

Fe(CN) ₆ ^4- +CuFe(CN) ₆ +O ₂ +8H ⁺ ＝2Cu ₂ Fe(CN) ₆ (brown red)↓+4H ₂ O

4Ag(CN) ₂ ^- +Fe(CN) ₆ ^4- +8H ⁺ ＝8HCN+Ag ₄ Fe(CN) ₆ ↓(gray white)

Ag(CN) ₂ ^- +SCN ^- +2H ⁺ ＝2HCN+AgSCN↓ (gray)

Ni(CN) ₄ ^2- +4H ⁺ +Fe(CN) ₆ ^4- ＝4HCN+Ni ₂ Fe(CN) ₆ ↓

In step S10b, the middle part of the stripping tower is filled with packing, which can increase the gas-liquid contact area; the top of the stripping tower is equipped with a wire mesh demister, which can prevent the liquid phase substances from being blown out of the stripping tower and pollute the environment. Since most of HCN is formed by the dissociation of cyanide complex ions under acidic conditions, the stripping degree of HCN is determined by the pH value of the wastewater after acidification treatment and the properties of the complex center ion (complex stability constant) . Since the stripping process is a continuous process in which an old dissociation equilibrium is broken to form a new dissociation equilibrium, the driving force is: (1) under acidic conditions, cyanide tends to form HCN and the weight loss of HCN in the gas phase In the turntable that has not reached equilibrium, the HCN in the liquid phase continuously escapes into the gas phase; (2) due to the complex center ion and other components in the wastewater form a more stable precipitate. These two impetus push the reaction continuously to the right. The specific blow-off process is as follows:

In the formula, Me ^m+ refers to Cu ²⁺ , Zn ²⁺ , Pb ²⁺ , Ni ²⁺ , etc., A refers to anions such as SCN ^- , Fe(CN) ₆ ^4- , and SS refers to insoluble substances, such as CuSCN, Zn ₂ Fe(CN) ₆ , Pb ₂ Fe(CN) ₆ , etc.

Preferably, the gas-water ratio in the stripping tower is 1:500 to 1:1000, such as 1:550, 1:600, 1:650, 1:700, 1:750, 1:800, 1:850 , 1:900 or 1:950. Under the condition of air-water ratio of 1:500～1:1000, air is blown in from the bottom of the tower by blower. After the gas-liquid phase contacts, the HCN in the wastewater can escape into the air and be carried into the absorption tower by the air.

Preferably, the non-oxidizing acid is selected from hydrochloric acid and/or dilute sulfuric acid. Both hydrochloric acid and dilute sulfuric acid will not undergo redox reactions with cyanide in cyanide-containing wastewater, and their role is only neutralization to adjust the pH value of cyanide-containing wastewater.

Preferably, the absorption liquid is sodium hydroxide. The use of sodium hydroxide as the absorption liquid can ensure sufficient alkalinity, so as to fully absorb HCN gas and convert it into NaCN, and reduce the cost of wastewater treatment by integrating resource recovery, so that the treatment cost of cyanide-containing wastewater is only the traditional chlor-alkali oxidation method. about two-thirds of the cost.

It is advisable to control the volume fraction of sodium hydroxide in the absorption raffinate to be 1-2% for the concentration and dosage of sodium hydroxide.

The pH value of the liquid phase is adjusted to 8-10 by using sodium hydroxide or lime, preferably sodium hydroxide.

In the step S40, a corresponding biochemical treatment system is selected according to the water volume of the wastewater after the coagulation and precipitation and the concentration of COD, nitrogen, phosphorus, cyanide and heavy metals in the wastewater, so that all factors of the effluent reach the standard;

Preferably, the biochemical treatment system includes at least one of hydrolytic acidification tank, anaerobic tank, anoxic tank, aerobic tank, and MBR membrane biological reaction system.

Preferably, the biochemical treatment system is composed of a hydrolytic acidification tank, an anaerobic tank, an anoxic tank, and an aerobic tank. To make the full factor of the effluent reach the standard, the residence time of the wastewater in each treatment tank is determined according to the nature of the wastewater.

More preferably, the biochemical treatment system is composed of a hydrolytic acidification tank, anaerobic tank, anoxic tank, an aerobic tank, and an MBR membrane biological reaction system. pool, aerobic pool, and MBR membrane bioreaction system, which can further make the effluent fully meet the standard.

Beneficial effects of the present invention: the present invention can make the pollutants such as COD, nitrogen, phosphorus, cyanide and heavy metals in the final effluent reach the standard by sequentially acidifying, stripping, coagulating and sedimenting, and biochemically treating the cyanide-containing wastewater generated by electroplating At the same time, the HCN produced after stripping treatment can be recycled, which can avoid resource waste and environmental pollution, and reduce the treatment cost of cyanide-containing wastewater. Compared with the traditional cyanide-containing wastewater treatment method, the cyanide-containing wastewater treatment method of the present invention is easier for industrial application.

Description of drawings

Fig. 1 is a process flow chart of a kind of cyanogen-containing wastewater treatment method of the present invention.

Fig. 2 is the process flow chart of another kind of cyanogen-containing wastewater treatment method of the present invention.

Fig. 3 is a process flow diagram of another cyanide-containing wastewater treatment method of the present invention.

detailed description

The technical solutions of the present invention will be further described below through specific embodiments.

Unless specifically stated, various raw materials of the present invention can be purchased commercially, or can be prepared according to conventional methods in the art.

Example 1

In the cyanide-containing wastewater of an electroplating park, the total cyanide content is 241mg/L, the CODcr is 335mg/L, the total copper is 86mg/L, the ammonia nitrogen is 18mg/L, and the total nitrogen is 26mg/L. The treatment method is as follows:

Acidification reaction: Firstly, industrial sulfuric acid with a mass concentration of 20% is added to the cyanide-containing wastewater to adjust the pH value of the cyanide-containing wastewater to 2, and acidification reaction occurs.

Stripping treatment: Send the acidified wastewater from the top of the tower to the stripping tower, and then blow air into the stripping tower according to the ratio of wastewater water volume to air volume of 1:1000 for stripping treatment, and the acidified residual liquid after stripping Into the residual liquid collection bucket.

Absorption treatment: The cyanide-containing gas generated by stripping is sent to the absorption tower and absorbed by the sodium hydroxide absorption liquid. The sodium hydroxide solution absorbs the cyanide-containing gas and reacts to generate sodium cyanide to obtain a sodium cyanide solution. The concentration of sodium solution reaches 15g/L, and sodium cyanide solution is recycled.

Coagulation and precipitation: add 10% sodium hydroxide solution to the acidified raffinate after stripping, adjust the pH value of the wastewater to 9, then add PAC and PAM to carry out coagulation and flocculation reaction, and the mixed solution after reaction Precipitation, the supernatant after precipitation enters the biochemical treatment system for further treatment, the sludge enters the sludge collection tank, and undergoes pressure filtration treatment, and the filtrate obtained by pressure filtration enters the cyanide-containing wastewater adjustment tank for treatment, and the obtained solid sludge is transported out for treatment. The dosage of PAC is 120mg/L, and the dosage of PAM is 8mg/L.

Biochemical treatment: Coagulation sedimentation effluent enters the biochemical treatment system to remove COD, ammonia nitrogen, total nitrogen, total phosphorus and other organic matter, a small amount of cyanide, heavy metals and other pollutants. The biochemical treatment system adopts the A3/O treatment process, that is, the coagulation and sedimentation effluent enters the hydrolytic acidification pool A1, the anaerobic pool A2, the anoxic pool A3, and the aerobic pool O in sequence, and the reflux ratio of the mixed liquid is 1:2, and the sludge reflux ratio The ratio is 1:1, the hydraulic retention time of hydrolytic acidification pool A1 is 6h, the hydraulic retention time of anaerobic pool A2 is 2h, the hydraulic retention time of anoxic pool A3 is 2h, and the hydraulic retention time of aerobic pool O is 10h.

In this example, after the cyanide-containing wastewater is treated by the above method, the effluent reaches the standard in Table 3 of the "Electroplating Pollutant Discharge Standard" (GB21900-2008).

Implementation Case 2

In the cyanide-containing wastewater of an electroplating park, the total cyanide content is 432mg/L, the CODcr is 468mg/L, the total copper is 121mg/L, the ammonia nitrogen is 23mg/L, and the total nitrogen is 38mg/L. The treatment method is as follows:

Acidification reaction: Firstly, industrial sulfuric acid with a mass concentration of 20% is added to the cyanide-containing wastewater to adjust the pH value of the cyanide-containing wastewater to 2, and acidification reaction occurs.

Primary stripping treatment: Send the acidified wastewater from the top of the tower to the primary stripping tower, and then blow air into the stripping tower according to the ratio of wastewater water volume to air volume of 1:1000 for stripping treatment. The acidified raffinate enters the primary raffinate collection barrel.

Primary absorption treatment: The cyanide-containing gas generated by stripping is sent to the primary absorption tower for absorption with sodium hydroxide absorption liquid, and the sodium hydroxide solution reacts after absorbing the cyanide-containing gas to generate sodium cyanide and obtain a sodium cyanide solution , when the concentration of the sodium cyanide solution reaches 16g/L, the sodium cyanide solution is recycled.

Secondary stripping treatment: the acidified raffinate after secondary stripping is sent from the top of the tower to the secondary stripping tower, and then air is blown into the stripping tower according to the ratio of wastewater water volume to gas volume of 1:1000 for stripping treatment , the acidified raffinate after stripping enters the secondary raffinate collection barrel.

Secondary absorption treatment: The cyanide-containing gas generated by stripping is sent to the secondary absorption tower for absorption with sodium hydroxide absorption liquid. The sodium hydroxide solution absorbs the cyanide-containing gas and reacts to generate sodium cyanide to obtain a sodium cyanide solution , when the concentration of the sodium cyanide solution reaches 16g/L, the sodium cyanide solution is recycled.

Coagulation and precipitation: add 10% sodium hydroxide solution to the acidified raffinate after the secondary air stripping, adjust the pH value of the wastewater to 9, and then add PAC and PAM to carry out coagulation and flocculation reaction. After the reaction, the mixing The supernatant after precipitation enters the biochemical treatment system for further treatment, the sludge enters the sludge collection tank, and undergoes pressure filtration treatment, and the filtrate obtained by pressure filtration enters the cyanide-containing wastewater adjustment tank for treatment, and the obtained solid sludge is transported out for treatment. The dosage of PAC is 120mg/L, and the dosage of PAM is 8mg/L.

Biochemical treatment: Coagulation sedimentation effluent enters the biochemical treatment system to remove COD, ammonia nitrogen, total nitrogen, total phosphorus and other organic matter, a small amount of cyanide, heavy metals and other pollutants. The biochemical treatment system adopts the A3/O treatment process, the reflux ratio of the mixed liquid is 1:2, the sludge reflux ratio is 1:1, the hydraulic retention time of the hydrolytic acidification tank A1 is 6.5h, and the hydraulic retention time of the anaerobic tank A2 is 2.5h. The hydraulic retention time of the anoxic pool A3 is 2.5h, and the hydraulic retention time of the aerobic pool O is 10h.

In this example, after the cyanide-containing wastewater is treated by the above method, the effluent reaches the standard in Table 3 of the "Electroplating Pollutant Discharge Standard" (GB21900-2008).

In the above examples, the treatment cost of cyanide-containing wastewater is about 2/3 of the treatment cost of the traditional chlor-alkali oxidation method.

The method for treating cyanide-containing wastewater of the invention has the advantages of simple process, stable operation, convenient control and low cost.

The above examples are only used to illustrate the detailed methods of the present invention, and the present invention is not limited to the above detailed methods, that is, it does not mean that the present invention can only be implemented depending on the above detailed methods. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. a method for treating cyanide-containing wastewater, is characterized in that, comprises the following steps: S10, sequentially performing acidification treatment and stripping treatment on the cyanide-containing wastewater to obtain a gas phase and a liquid phase; S20. Using an absorption liquid to absorb the gas phase for recycling to obtain an absorption raffinate; S30, performing coagulation and sedimentation treatment on the liquid phase while performing the step S20; S40, performing biochemical treatment on the wastewater after the coagulation and sedimentation treatment. 2. The method for treating cyanide-containing wastewater according to claim 1, characterized in that, in the step S30, the pH value of the liquid phase is first adjusted to 8-10, and then a coagulant and a flocculant are added for mixing. Coagulation treatment. 3. The method for treating cyanide-containing wastewater according to claim 2, characterized in that, the liquid phase obtained in the step S10 is subjected to acidification treatment and stripping treatment again. 4. The method for treating cyanide-containing wastewater according to claim 2, characterized in that, the liquid phase obtained in the step S10 is repeatedly treated several times according to the steps S10, S20, and S30. 5. the cyanogen-containing wastewater treatment method according to claim 2, is characterized in that, described step S10 comprises the following steps: S10a: adding a non-oxidizing acid to the cyanide-containing wastewater, and adjusting its pH value to 1-3, so as to hydrolyze the cyanide in the cyanide-containing wastewater; S10b: The acidified waste water containing cyanide is introduced from the top of the stripping tower, and air is blown in from the bottom of the tower by a blower, so as to blow out the gas phase through the air. 6. The method for treating cyanide-containing wastewater according to claim 5, characterized in that, the gas-water ratio in the stripping tower is 1:500 to 1:1000. 7. The method for treating cyanide-containing wastewater according to claim 5, wherein the non-oxidizing acid is selected from hydrochloric acid and/or dilute sulfuric acid. 8. The method for treating cyanide-containing wastewater according to any one of claims 1 to 7, wherein the absorption liquid is sodium hydroxide; the volume fraction of sodium hydroxide in the absorption raffinate is 1 to 2%. . 9. The method for treating cyanide-containing wastewater according to any one of claims 2 to 7, characterized in that sodium hydroxide or lime is used to adjust the pH value of the liquid phase to 8-10. 10. according to the described method for treating cyanide-containing wastewater according to any one of claims 1 to 7, it is characterized in that, in the step S40, according to the water yield of the wastewater after the coagulation precipitation and the COD and nitrogen in the wastewater , Phosphorus, cyanide and heavy metal concentration select the corresponding biochemical treatment system to make the effluent fully up to the standard; Preferably, the biochemical treatment system includes at least one of hydrolytic acidification tank, anaerobic tank, anoxic tank, aerobic tank, and MBR membrane biological reaction system.