CN-118359327-B - Method for treating high cyanide coking wastewater

CN118359327BCN 118359327 BCN118359327 BCN 118359327BCN-118359327-B

Abstract

The invention provides a method for treating high cyanide coking wastewater, which belongs to the technical field of wastewater treatment, and comprises the steps of sequentially carrying out pretreatment, oxidation and photolysis treatment, physical and chemical treatment, biochemical treatment, resin treatment and electrolytic treatment on the high cyanide coking wastewater to obtain treated water with cyanide content below 0.2 mg/L. The method of the invention sequentially treats cyanide in the wastewater through 6 treatment procedures, the cyanide in the treated wastewater can reach below 0.2mg/L, and the cyanide removal effect is good.

Inventors

WEI ZIZHONG
WANG CHONGPU
LI HUANHUAN
REN SHAOBO

Assignees

河北协同水处理技术有限公司

Dates

Publication Date: 20260508
Application Date: 20240314

Claims (6)

1. A method for treating high cyanide coking wastewater is characterized in that the method comprises the steps of sequentially carrying out pretreatment, oxidation and photolysis treatment, physical and chemical treatment, biochemical treatment, resin treatment and electrolytic treatment on the high cyanide coking wastewater to obtain treated water with cyanide content below 0.2 mg/L; The pretreatment comprises the steps of adding a cyanide remover A into high cyanide coking wastewater, stirring, adding polyacrylamide anions, stirring, and standing to precipitate out water; The oxidation and photolysis treatment is to introduce ozone into the pretreated effluent for aeration stirring, then add a catalyst, apply sunlight or ultraviolet irradiation for a preset time and then discharge water; The physical and chemical treatment is to add a cyanogen removing agent B into the effluent after the oxidation and photolysis treatment, add polyacrylamide anions after stirring, and treat the effluent after a preset time; the biochemical treatment is to inoculate domesticated cyanogen removing bacteria into a water tank firstly, add a carbon source, start to be introduced into the water tank after physical and chemical treatment when COD in the water tank is degraded to below 500, stir after the water tank is treated for a preset time, and then stand the water tank for standby, and take supernatant fluid; The resin treatment is to transfer the supernatant after biochemical treatment into ion exchange resin or adsorption resin for treatment; the electrolytic treatment is to treat the effluent after the resin by using a carbon rod; In pretreatment, the cyanide remover A consists of ferrous iron, polyaluminium and zinc salt, wherein the ferrous iron is ferrous sulfate or ferrous chloride, the zinc salt is any one of zinc sulfate, zinc chloride or zinc nitrate, the molar ratio of ferrous iron to polyaluminium to zinc salt is 5:3:2, the mass ratio of cyanide to the cyanide remover A in the high cyanide coking wastewater is 1:30-40, and the addition amount of polyacrylamide anions is 5-10ppm; in the physicochemical treatment, the cyanide remover B consists of active carbon, polymeric ferric sulfate, copper sulfate, cerium oxide, glycol and dicyandiamide-formaldehyde polycondensate according to the mass ratio of 2-3:2-3:1-2:1-2:0.2-0.5:1-1.5, wherein the mass ratio of cyanide to the cyanide remover B in effluent after oxidative and photolysis treatment is 1:30-50, and the addition amount of polyacrylamide anions is 4-7ppm.
2. The method for treating high cyanide coking wastewater according to claim 1, wherein in the oxidative photocatalytic treatment, the catalyst is prepared according to a mass ratio of titanium dioxide to silicon dioxide of 1:1-1.5, sunlight is more than or equal to 9 thousand lx, ultraviolet is more than or equal to 2 thousand lx, and water is discharged after irradiation is more than or equal to 3.5 hours.
3. The method for treating high cyanide coking wastewater according to claim 1, wherein in biochemical treatment, the inoculation amount of the cyanide removing bacteria is 10-20% of the volume of wastewater in a water tank, the carbon source is glucose, the addition amount is 1000ppm, the environmental conditions of the water tank are that the temperature is 32 ℃, the pH is=9, the aeration amount is not less than 2.5L/min, the effluent water is firstly introduced into the biochemical treatment water tank in the first day by an amount which is not more than 20% of the total volume of the cyanide removing bacteria, the water amount which is increased every day is not more than 1.1 times of the water amount of the previous day until the normal water inflow amount is reached, the biochemical treatment time is not less than 30h, and the water is left stand for more than 3 hours.
4. The method for treating high cyanide coking wastewater according to claim 1, wherein in the resin treatment, the resin particle size is 0.4 to 0.7mm and the flow rate is controlled to be 2 to 3Bv/h.
5. The method for treating high cyanide coking wastewater according to claim 1, wherein in the electrolysis treatment, a plurality of groups of carbon rods are selected as anodes and cathodes, the distance between the carbon rods is 20-30 cm, the current is 0.3-0.5A, the voltage is controlled to 8-10V, and water is discharged after the electrolysis time exceeds 50 minutes.
6. A method for treating high cyanide coking wastewater according to any one of claims 1 to 5 in which the cyanide content in the high cyanide coking wastewater is not less than 1000 mg/L.

Description

Method for treating high cyanide coking wastewater Technical Field The invention relates to cyanide treatment, in particular to a method for treating high cyanide in coking wastewater, and belongs to the technical field of wastewater treatment. Background Cyanide refers particularly to compounds with cyano groups (CN) in which the carbon and nitrogen atoms are connected by triple bonds. This triple bond imparts a relatively high degree of stability to the cyano group, allowing it to exist as a whole in a typical chemical reaction. This group is often referred to as pseudohalogen because it has similar chemical properties to halogen. Cyanide, which is commonly known as inorganic cyanide, refers to inorganic salts containing cyanide ions (CN-) and may be considered salts of hydrocyanic acid (HCN), commonly known as potassium cyanide and sodium cyanide. They are often extremely toxic. The organic cyanide compound is formed by bonding a cyano group to another carbon atom through a single bond. Depending on the mode of incorporation, organic cyanides can be classified as nitriles (C-CN) and isonitriles (C-NC), and the corresponding cyano groups can be referred to as nitrile groups (-CN) or isonitrile groups (-NC). Many cyanides, which release hydrogen cyanide or cyanide ions either upon heating or upon reaction with an acid or in air with tissue, have the same highly toxic effects as hydrogen cyanide. Cyanide in coking wastewater is generated by a series of chemical reactions in the production process of coke, and the existence forms of cyanide are different in the treatment process of coking wastewater. The cyanide, alkali metal cyanide and metal cyanide complex with weaker complexing ability are easier to remove, the residual cyanide in the coking wastewater after biochemical treatment mainly takes ferricyanide with high stability as the main component, and the common oxidizing agent has poorer treatment effect on the cyanide. Along with the improvement of environmental protection requirements, once raw cyanide fluctuates after the wastewater recycling and zero emission device is operated, the concentrated cyanide index is easily affected, the cyanide reducing capability of the current materialization technology is limited, the cyanide of the effluent exceeds the standard, and the environmental protection pressure is high. Disclosure of Invention Aiming at the problems, the invention provides a method for treating high cyanide coking wastewater, which solves the technical problems of high cyanide content and high environmental protection pressure caused by difficult treatment of high cyanide in the coking wastewater in the prior art. The technical scheme of the method for treating the high cyanide coking wastewater is that the method comprises the steps of sequentially carrying out pretreatment, biochemical treatment, oxidation and photolysis treatment, physical and chemical treatment, resin treatment and electrolytic treatment on the high cyanide coking wastewater to obtain treated water with cyanide content below 0.2 mg/L. Further, the pretreatment is to add a cyanide remover A into the high cyanide coking wastewater for stirring, then add polyacrylamide anions for stirring, and then stand for precipitation to obtain water; The oxidation and photolysis treatment is to introduce ozone into the pretreated effluent for aeration stirring, then add a catalyst, apply sunlight or ultraviolet irradiation for a preset time and then discharge water; The physical and chemical treatment is to add a cyanogen removing agent B into the effluent after the oxidation and photolysis treatment, add polyacrylamide anions after stirring, and treat the effluent after a preset time; the biochemical treatment is to inoculate domesticated cyanogen removing bacteria into a water tank firstly, add a carbon source, start to be introduced into the water tank after physical and chemical treatment when COD in the water tank is degraded to below 500, stir after the water tank is treated for a preset time, and then stand the water tank for standby, and take supernatant fluid; The resin treatment is to transfer the supernatant after biochemical treatment into ion exchange resin or adsorption resin for treatment; the electrolytic treatment is to treat the effluent after the resin by using a carbon rod. Further, in the pretreatment, the cyanide remover A consists of ferrous iron, polyaluminium and zinc salt, wherein the ferrous iron is ferrous sulfate or ferrous chloride, the zinc salt is any one of zinc sulfate, zinc chloride or zinc nitrate, the molar ratio of ferrous iron to polyaluminium to zinc salt is 5:3:2, the mass ratio of cyanide to the cyanide remover A in the high cyanide coking wastewater is 1:30-40, and the addition amount of polyacrylamide anions is 5-10ppm. In the oxidation and photolysis treatment, the catalyst is prepared according to the mass ratio of titanium dioxide to silicon dioxide of 1:1-1.5, sunlight is more than or eq