TWI685470B - Cyanide-containing wastewater treatment method and equipment therefor - Google Patents

Abstract

A cyanide-containing wastewater treatment method and an equipment therefor are provided. The cyanide-containing wastewater treatment method includes steps of: (a) providing a cyanide-containing wastewater; and (b) adding a cobalt-containing agent to the cyanide-containing wastewater so as to remove the cyanide from the cyanide-containing wastewater, wherein a ratio of an cobalt concentration in the cyanide-containing wastewater after the cobalt-containing agent added into the cyanide-containing wastewater and a total cyanide concentration in the cyanide-containing wastewater are from 0.2:1 to 2:1.

Description

Cyanide-containing wastewater treatment method and equipment

The invention relates to a method and equipment for treating cyanide-containing waste water, in particular to a method and equipment for treating cyanide-containing waste water using a cobalt ion-containing agent.

Cyanide is a carbon-containing free radical. The most common are hydrogen cyanide, sodium cyanide and potassium cyanide. All cyanide compounds are toxic, especially hydrogen cyanide, which is deadly. Short-term contact with cyanide can cause shortness of breath, tremor and other nervous system effects. Prolonged contact with cyanide can cause dehydration, thyroid disease, nerve damage and death.

The source of cyanide usually comes from the wastewater of various industries such as electroplating, metal processing, automobile parts manufacturing, steel manufacturing, pharmaceutical production, mining and plastic production. Cyanide is usually a pollutant, and industrial wastewater usually contains 0.01 to 10 mg/liter of total cyanide. The cyanide in industrial wastewater is usually present in complex species. Thiocyanate is the most important cyanide compound in industrial wastewater and is often present in coal coke and coal conversion wastewater. In order to protect the environment and water bodies, cyanide-containing wastewater in various industries needs to be treated before being discharged into the environment.

The currently known cyanide-containing wastewater treatment method is to add sodium hypochlorite to the cyanide-containing wastewater. However, this treatment method will double the volume of waste water, and if there is residual ammonia in the water, this harmful substance will be chloramine.

In addition, the known technology proposes to add activated carbon powder to cyanide-containing wastewater and add ferrous ion salt for ultrasonic vibration and adjust the pH to 8-10, while adding copper oxide as a catalyst can effectively remove wastewater Cyanide. However, this type of treatment requires the addition of multiple chemicals, and it is necessary to treat a large amount of wastewater in the ultrasonic reactor, and the use of the Fenton method will cause a large amount of sludge to be treated separately, which is not in line with economic benefits. Furthermore, the known technology proposes a treatment method for treating cyanide-containing wastewater using laccase. However, the activity of laccase is susceptible to environmental influences The noise is reduced, and the storage is not easy, the cost is higher than the general chemical agents and the reaction time is long, and the water temperature needs to be controlled at 20 ~ 35 ℃, so it is not suitable for summer in subtropical regions. The known technology also proposes a treatment method for removing waste water containing cyanide by using basic Fenton reaction. However, this treatment method needs to adjust the pH value of the treated wastewater to 9-12, then add hydrogen peroxide and ferrous sulfate, and additionally add copper oxide as a catalyst. At the beginning, the above treatment method needs to use alkali to adjust the pH value of the wastewater, and after the reaction is completed, an acid is needed to adjust the pH value to meet the discharge standard. The added amount of acid and alkali is large, resulting in high treatment cost, and the Fenton method will generate a large amount of sludge, which requires additional sludge treatment costs.

Therefore, it is necessary to provide a cyanide-containing wastewater treatment method and equipment to solve the problems of conventional technology.

The main purpose of the present invention is to provide a cyanide-containing wastewater treatment method and equipment, so that the treated wastewater conforms to environmental standards and does not significantly increase the volume of the treated wastewater, and thus has economic benefits.

The secondary object of the present invention is to provide a cyanide-containing wastewater treatment method and equipment, which can quickly treat cyanide-containing wastewater and at the same time have economic benefits, and thereby reduce the concentration of cyanide-containing wastewater to meet the purpose of environmental protection.

To achieve the above objective, the present invention provides a method for treating cyanide-containing wastewater, which includes the steps of: (a) providing a cyanide-containing wastewater; and (b) adding a cobalt ion-containing agent to the cyanide-containing wastewater, to Removing cyanide in the cyanide-containing wastewater, wherein in the cyanide-containing wastewater, the cobalt ion-containing agent is added to the cyanide-containing wastewater after the concentration of a cobalt ion in the cyanide-containing wastewater and the cyanide-containing wastewater The total cyanide concentration in the chemical wastewater is 0.2:1 to 2:1.

In one embodiment of the present invention, the total cyanide concentration in the cyanide-containing wastewater is 15 ppm to 60 ppm, and the pH value is 6 to 9.

In one embodiment of the present invention, after the cobalt ion-containing agent is added to the cyanide-containing wastewater, mixing is performed for 5 to 15 minutes to form a mixed wastewater.

In one embodiment of the present invention, the method for treating cyanide-containing wastewater further includes: adding a cationic flocculant to the mixed wastewater, wherein an added concentration of the cationic flocculant in the mixed wastewater is 0.01 ppm to 1ppm.

In one embodiment of the present invention, after the cationic flocculant is added to the mixed wastewater, mixing is performed for 3 to 15 minutes; and after the cationic flocculant and the mixed wastewater are mixed, a precipitation procedure is performed, and a precipitation of the precipitation procedure The time is 5 to 15 minutes.

Another embodiment of the present invention provides a cyanide-containing wastewater treatment equipment, including: a fast-mixing tank; an inlet pipe configured to introduce a cyanide-containing wastewater into the fast-mixing tank; and a cobalt ion-containing agent addition tank , Configured to add a cobalt ion-containing agent to the fast mixing tank and mix with the cyanide-containing wastewater to remove cyanide in the cyanide-containing wastewater, wherein in the cyanide-containing wastewater, the cobalt-containing After the ionic agent is added to the cyanide-containing wastewater, the concentration of a cobalt ion in the cyanide-containing wastewater and the total cyanide concentration in the cyanide-containing wastewater are 0.2:1 to 2:1.

In one embodiment of the present invention, the total cyanide concentration in the cyanide-containing wastewater is 15 ppm to 60 ppm, and the pH value is 6 to 9.

In one embodiment of the present invention, the cyanide-containing wastewater treatment equipment further includes an aerator configured to send air to the fast-mixing tank to apply the cobalt ion-containing agent to the cyanide-containing wastewater After mixing, the cobalt ion-containing agent is mixed with the cyanide-containing wastewater and then aerated in the fast-mixing tank for 5 to 15 minutes.

In one embodiment of the present invention, the cyanide-containing wastewater treatment equipment further includes: a slow mixing tank configured to mix the cobalt-ion-containing reagent with the cyanide-containing wastewater after the cobalt-ion-containing reagent is mixed with the cyanide-containing wastewater A mixed wastewater after the cyanide-containing wastewater is mixed is introduced into the slow mixing tank; and a cationic flocculant addition tank configured to add a cationic flocculant to the slow mixing tank, wherein the cationic flocculant in the mixed wastewater The concentration of one addition is 0.01 ppm to 1 ppm. After the cationic flocculant is added to the mixed wastewater, mixing is performed for 3 to 15 minutes.

In one embodiment of the present invention, the cyanide-containing wastewater treatment equipment further includes: a coagulation sedimentation tank configured to mix the cationic flocculant with the mixed wastewater, and then perform a precipitation process. A settling time is 5 to 15 minutes.

S11~S12‧‧‧Step

20‧‧‧ Wastewater treatment equipment

21‧‧‧Cyanide-containing wastewater inlet pipe

22‧‧‧Fast mixing pool

23‧‧‧Cobalt-containing agent addition tank

24‧‧‧Slow mixing pool

25‧‧‧Cationic flocculant addition tank

26‧‧‧Coagulation sedimentation tank

27‧‧‧Aerator

Figure 1: Schematic diagram of cyanide-containing wastewater treatment method according to an embodiment of the invention; Figure 2: Schematic diagram of cyanide-containing wastewater treatment equipment according to an embodiment of the invention

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the preferred embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings, which will be described in detail below. Furthermore, the terms of direction mentioned in the present invention, such as up, down, top, bottom, front, back, left, right, inner, outer, side, surrounding, center, horizontal, horizontal, vertical, longitudinal, axial, The radial direction, the uppermost layer or the lowermost layer, etc., are only the directions referring to the attached drawings. Therefore, the directional terminology is used to illustrate and understand the present invention, not to limit the present invention.

As used herein, the term "cyanide" means with cyanide ion (CN ^-) compounds in which the carbon atoms and nitrogen atoms are connected by a triple bond.

As used herein, the term "total cyanide" or "total cyanide" refers to the inclusion of various metal cyanide complexes. The water sample is mixed with hot phosphoric acid and irradiated with ultraviolet rays to decompose or digest these complexes and convert it into hydrocyanic acid (HCN _(aq) ). Donor stream containing hydrocyanic acid is breathable through silicone rubber. The membrane, where the hydrocyanic acid is dialyzed in the form of HCN _(g) and absorbed in an acceptor stream containing dilute sodium hydroxide (this procedure is equivalent to digestion and distillation), then enters the flow analysis system (Flow injection analysis, FIA). Cyanide ions and Chloramine-T (Chloramine-T) react at a pH of less than 8 to form cyanogen chloride (CNCl). This compound reacts with a pyridine-barbituric acid (Pyridine-barbituric acid) solution to produce For the purple substance, use a spectrophotometer to measure its absorbance at a wavelength of 570 nm, and the total cyanide content in the water sample can be obtained.

Please refer to FIG. 1, which shows a method for treating cyanide-containing wastewater according to an embodiment of the present invention, which includes the steps of: (S11) providing a cyanide-containing wastewater; and (S12) adding a cobalt ion-containing agent In the cyanide-containing wastewater, to remove cyanide in the cyanide-containing wastewater, wherein in the cyanide-containing wastewater, the cobalt ion-containing agent is added to the cyanide-containing wastewater in the cyanide-containing wastewater A cobalt ion concentration and a total fluorine concentration in the cyanide-containing wastewater are 0.2:1 to 2:1.

Please refer to FIG. 2 for a schematic diagram of a cyanide-containing wastewater treatment equipment according to an embodiment of the present invention. The cyanide-containing wastewater treatment equipment 20 includes: a fast-mixing tank 22; a cyanide-containing wastewater inlet pipe 22 configured to introduce a cyanide-containing wastewater into the fast-mixing tank 22; and a cobalt ion-containing agent addition The tank 23 is configured to add a cobalt ion-containing agent to the fast-mixing tank 22 and mix it with the cyanide-containing wastewater to remove cyanide in the cyanide-containing wastewater, in which In the cyanide-containing wastewater, the concentration of a cobalt ion in the cyanide-containing wastewater and the total cyanide concentration in the cyanide-containing wastewater after the cobalt-ion-containing agent is added to the cyanide-containing wastewater are 0.2:1 to 2:1.

In the present invention, the implementation details of the above steps, the corresponding processing equipment and the principle of the first embodiment will be described in detail one by one using FIGS. 1 and 2 below.

Please refer to Fig. 1 and Fig. 2, first perform step (S11) to provide a cyanide-containing wastewater. Preferably, the total cyanide concentration in the cyanide-containing wastewater is 15 ppm to 60 ppm (eg milligrams per liter), and the pH value is 6 to 9. In this embodiment, the cyanide-containing wastewater is the effluent water of the coking wastewater of a steel plant or the secondary effluent water after biological treatment, and its pH value is 7-8. The cyanide-containing wastewater contains a total cyanide concentration of 15 ppm to 50 ppm. Next, the cyanide-containing wastewater is introduced into the fast mixing tank 22 through the cyanide-containing wastewater inlet pipe 22. Optionally, before entering the fast mixing tank 22, the cyanide-containing wastewater may be added with an iron-containing coagulant (eg, containing ferric ions). Next, step (S12) is performed to add a cobalt ion-containing agent to the cyanide-containing wastewater to remove cyanide in the cyanide-containing wastewater, wherein the cobalt ion-containing agent is added to the cyanide-containing wastewater The concentration of a cobalt ion in the cyanide-containing wastewater and the total fluorine concentration in the cyanide-containing wastewater after the cyanide wastewater is 0.2:1 to 2:1. For example, when the cobalt ion-containing agent is added to the cyanide-containing wastewater after the cobalt ion concentration in the cyanide-containing wastewater and the total cyanide concentration in the cyanide-containing wastewater are 2:1, when the If the total cyanide concentration in the cyanide-containing wastewater is 15 ppm to 50 ppm, the cobalt ion-containing agent is set to be added to the cyanide wastewater, and then the entire cyanide-containing wastewater contains cobalt ions in a concentration of 30 ppm to 100 ppm. The cobalt ion-containing agent addition tank 23 adds a cobalt ion-containing agent to the fast-mixing tank 22 and mixes with the cyanide-containing wastewater to remove cyanide in the cyanide-containing wastewater. Preferably, after the cobalt ion-containing agent is added to the cyanide-containing wastewater, the cobalt ion concentration in the cyanide-containing wastewater and the total cyanide concentration in the cyanide-containing wastewater are 1:1. For example, when the total cyanide concentration in the cyanide-containing wastewater in the fast-mixing tank 22 is 15 mg/liter, and the volume of the fast-mixing tank 22 is 100 liters, then add 1.5 grams of the cobalt ion-containing agent So that the cobalt ion in the cyanide-containing wastewater is maintained at 15 mg/L. Preferably, the method for treating the cyanide-containing wastewater includes the steps of: adding the cobalt ion-containing agent to the cyanide-containing wastewater, and mixing for 5 to 15 minutes to form a mixed wastewater. After adding the cobalt ion-containing agent to the cyanide-containing wastewater, mixing Mix for 5 to 15 minutes to form a mixed wastewater. For example, after the cobalt ion-containing agent is added to the fast mixing tank 22 and mixed with the cyanide-containing wastewater, mixing is performed in the fast mixing tank 22 for 5 to 15 minutes. Optionally, the cyanide-containing wastewater treatment equipment 20 further includes an aerator 27 configured to send air to the fast-mixing tank 22 to mix the cobalt ion-containing agent with the cyanide-containing wastewater . After the cobalt ion-containing agent is added to the fast mixing tank 22, aeration is performed in the fast mixing tank 22 for 5 to 15 minutes, so that the cobalt ion-containing agent can react with the cyanide-containing wastewater.

In addition, in the embodiment of the present invention, the method for treating cyanide-containing wastewater further includes the step of: adding a cationic flocculant to the mixed wastewater, wherein the added concentration of the cationic flocculant in the mixed wastewater is 0.01 ppm to 1ppm.

As shown in FIG. 2, the cyanide-containing wastewater treatment equipment 20 further includes: a slow mixing tank 24 and a cationic flocculant addition tank 25. The slow mixing tank 24 is configured to, after the cobalt ion-containing agent and the cyanide-containing wastewater are mixed, introduce a mixed wastewater into which the cobalt ion-containing agent and the cyanide-containing wastewater are mixed, and the slow mixing tank 24, and The cationic flocculant addition tank 25 is configured to add the cationic flocculant to the slow mixing tank 24. As described above, the step of adding the cationic flocculant to the mixed wastewater, after introducing the mixed wastewater into the slow mixing tank 24, the cationic flocculant adding tank 25 adds a cationic flocculant to the slow mixing tank 24, wherein the cation One added concentration of the flocculant in the mixed wastewater is 0.01 ppm to 1 ppm. After the cationic flocculant is added to the mixed wastewater, mixing is performed for 3 to 15 minutes.

Optionally, in the embodiment of the present invention, the method for treating cyanide-containing wastewater further includes the steps of: adding the cationic flocculant to the mixed wastewater, mixing for 3 to 15 minutes; and the cationic flocculant and After the mixed wastewater is mixed, a precipitation process is performed, and a precipitation time of the precipitation process is 5 to 15 minutes.

Optionally, as shown in FIG. 2, the cyanide-containing wastewater treatment equipment 20 further includes: a coagulation sedimentation tank 26. After the cationic flocculant and the mixed wastewater are mixed, the mixed wastewater added with the cationic flocculant is introduced into the coagulation sedimentation tank 26 to perform a precipitation process, and a precipitation time of the precipitation process is 5 to 15 minutes. After the cobalt ion-containing agent and the cationic flocculant are added to the cyanide-containing wastewater according to the above, the cyanide in the cyanide-containing wastewater can react with cobalt ions, and help to settle in the coagulation sediment by the cationic flocculant In the pond 26, the cyanide in the cyanide-containing wastewater can be removed in this way.

The following Table 1 is an example of the present invention for adding different cobalt ion-containing powder with a total cyanide concentration of 1:1 to different water samples in cyanide-containing wastewater, and thoroughly mixing and reacting for 5-10 minutes. Add 1ppm of cationic flocculant to part of the water sample, and mix for 5 minutes and settling for 10 minutes. According to the results, the removal effect of adding cobalt ion-containing powder and cationic flocculant can reach 72%-88%, while the removal effect of adding only cobalt ion-containing powder (without adding cationic flocculant) can reach 63.7%.

Although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with this skill can be regarded as within the spirit and scope of the present invention. Various changes and modifications, so the scope of protection of the present invention should be defined as the scope of the attached patent application Whichever prevails.

S11~S12‧‧‧Step

Claims (10)

A method for treating cyanide-containing wastewater, comprising the steps of: (a) providing a cyanide-containing wastewater; and (b) adding a cobalt ion-containing agent to the cyanide-containing wastewater to remove cyanide in the cyanide-containing wastewater Compound, wherein in the cyanide-containing wastewater, the cobalt ion-containing agent is added to the cyanide-containing wastewater after the concentration of a cobalt ion in the cyanide-containing wastewater and a total cyanide concentration in the cyanide-containing wastewater is 0.2:1 to 2:1. The method for treating cyanide-containing wastewater as described in item 1 of the patent application scope, wherein the total cyanide concentration in the cyanide-containing wastewater before the cobalt ion-containing agent is added to the cyanide-containing wastewater is 15 ppm to 60 ppm, And pH is 6 to 9. The method for treating cyanide-containing wastewater as described in item 1 of the patent application scope, wherein after adding the cobalt ion-containing agent to the cyanide-containing wastewater, mixing is performed for 5 to 15 minutes to form a mixed wastewater. The method for treating cyanide-containing wastewater as described in item 3 of the patent application scope further comprises: adding a cationic flocculant to the mixed wastewater, wherein the concentration of the cationic flocculant in the mixed wastewater is 0.01 ppm to 1ppm. The method for treating cyanide-containing wastewater as described in item 4 of the patent application scope, wherein after adding the cationic flocculant to the mixed wastewater, mixing is performed for 3 to 15 minutes; and after mixing the cationic flocculant with the mixed wastewater, A precipitation procedure is carried out, with a precipitation time of 5 to 15 minutes. A cyanide-containing wastewater treatment equipment, including: a fast mixing tank; An inflow pipe, configured to introduce a cyanide-containing wastewater into the fast mixing tank; and a cobalt ion-containing agent addition tank, configured to add a cobalt ion-containing agent to the fast mixing tank and the cyanide-containing agent The cyanide wastewater is mixed to remove cyanide in the cyanide-containing wastewater, wherein in the cyanide-containing wastewater, the cobalt ion-containing agent is added to the cyanide-containing wastewater after a cobalt ion in the cyanide-containing wastewater The concentration and the total cyanide concentration in the cyanide-containing wastewater are 0.2:1 to 2:1. The cyanide-containing wastewater treatment facility as described in item 6 of the patent application scope, wherein the total cyanide concentration in the cyanide-containing wastewater before the cobalt ion-containing agent is added to the cyanide-containing wastewater is 15 ppm to 60 ppm, and The pH is 6 to 9. The cyanide-containing wastewater treatment equipment as described in item 6 of the patent application scope further includes an aerator configured to send air to the fast-mixing tank to apply the cobalt ion-containing agent to the cyanide-containing wastewater After mixing, the cobalt ion-containing agent is mixed with the cyanide-containing wastewater and then aerated in the fast-mixing tank for 5 to 15 minutes. The cyanide-containing wastewater treatment equipment as described in item 8 of the scope of the patent application further includes: a slow mixing tank configured to mix the cobalt-ion-containing agent with the cyanide-containing wastewater after the cobalt-containing agent is mixed with the cyanide-containing wastewater A mixed wastewater after the cyanide-containing wastewater is mixed is introduced into the slow mixing tank; and a cationic flocculant addition tank configured to add a cationic flocculant to the slow mixing tank, wherein the cationic flocculant in the mixed wastewater The concentration of one addition is 0.01 ppm to 1 ppm. After the cationic flocculant is added to the mixed wastewater, mixing is performed for 3 to 15 minutes. Cyanide-containing wastewater treatment equipment as described in item 9 of the scope of patent application, including Containing: a coagulation sedimentation tank, configured to mix the cationic flocculant with the mixed wastewater, and then perform a sedimentation process. The sedimentation time of the sedimentation process is 5 to 15 minutes.

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