Treatment method of environment-friendly HEDP cyanide-free alkaline copper plating wastewater

Abstract

The invention relates to a treatment method of environment-friendly HEDP cyanide-free alkaline copper plating wastewater, and belongs to the field of wastewater treatment. The treatment method comprises two steps of complex breaking treatment and coagulating sedimentation treatment on the wastewater. The complex breaking treatment comprises the following steps: adding calcium chloride or calcium hydroxide into the wastewater to react with the wastewater, and breaking the complexing action of HEDP-Cu. And the step of coagulating sedimentation treatment comprises the following steps: adjusting the pH value of the wastewater to 11.5-13.5 by using alkaline substances such as calcium hydroxide or sodium hydroxide or lime, then adding PAM, then carrying out natural sedimentation, and filtering the supernate through a sand filter. The problems that an existing method is high in treatment cost and complex in operation are solved, adopted agents are easy to obtain and low in price, and the method is easier to popularize.

Description

Technical Field

[0001] The invention relates to a method for treating environment-friendly HEDP cyanide-free alkaline copper plating wastewater, belonging to the field of wastewater treatment. Background Art

[0002] Copper is increasingly used in surface protection. Copper has unique characteristics such as low resistivity and high resistance to electromigration. Cyanide copper plating is the most widely used copper plating process. However, cyanide is highly toxic and has great harm to the environment and human health. Environmentally friendly HEDP cyanide-free alkaline copper plating is considered to be one of the most likely environmentally friendly processes to replace cyanide copper plating.

[0003] The wastewater generated by environmentally friendly HEDP cyanide-free alkaline copper plating has almost no removal rate using conventional alkaline precipitation methods. If the wastewater is mixed with other electroplating heavy metal wastewater, it will make it difficult to precipitate and remove other wastewater. And if it is not effectively treated, once it enters the surrounding soil, water and atmospheric environment, it will cause serious environmental pollution.

[0004] The invention patent application with publication number CN111592150A discloses a method for treating hydroxyethylidene diphosphonic acid copper plating wastewater. The technical feature of the patent is that an anion exchange resin and hydrated zirconium oxide are used to form a zirconium-based nanocomposite material, and the hydroxyethylidene diphosphonic acid copper plating wastewater is adjusted to a suitable alkaline condition. The zirconium-based nanocomposite material is used as an adsorbent to form a ternary complex with HEDP-Cu in the wastewater under alkaline conditions. However, the disadvantage is that the removal efficiency is not high (only about 50%), and it needs to be applied in an adsorption column, and the treatment efficiency is not high, which limits its application.

[0005] The invention patent with publication number CN108383269B provides a combined treatment method for HEDP copper plating wastewater. The copper and total phosphorus content in the wastewater supernatant after treatment by this method meet the requirements of Table 3 of CB21900-2008 "Electroplating Pollutant Emission Standards". However, this treatment method requires the addition of a large amount of chemical reagents, including sodium dithiocarbamate, etc., which may cause secondary pollution, so the actual applicability is not high.

[0006] The invention patent with publication number CN112759169A provides a method for treating copper-HEDP-containing wastewater. The total copper and total phosphorus content of the wastewater treated by this method meet the requirements of the water pollutant emission limit in Table 2 of GB21900-2008 "Electroplating Pollutant Emission Standard", that is, the total copper ≤ 0.5 mg / L and the total phosphorus ≤ 1.0 mg / L. However, this treatment method requires the addition of a strong oxidant persulfate and the use of MIEX magnetic resin, which has a high treatment cost and may cause secondary pollution.

[0007] At present, advanced oxidation technology has been widely used in the decomposition of complexes, such as photocatalysis, electrochemistry, Fenton method, ozone oxidation, etc. However, the photocatalytic oxidation method has high requirements for reaction conditions and has great limitations in practical applications; the electrochemical method is greatly limited by electrode materials and has poor removal effect on high-concentration complexed heavy metals; the traditional Fenton method has the disadvantages of low hydrogen peroxide utilization, high cost, and high requirements for process control.

[0008] Therefore, it is very necessary to find a method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater with low treatment cost, simple operation, short reaction time and good treatment effect. Summary of the invention

[0009] The technical problem to be solved by the present invention is to reduce the treatment cost of environmentally friendly HEDP cyanide-free alkaline copper plating wastewater, overcome the problems of complex treatment process and low treatment efficiency of environmentally friendly HEDP cyanide-free alkaline copper plating wastewater, and provide a method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater; the method includes two steps of complex breaking treatment and coagulation precipitation treatment of the wastewater. The complex breaking treatment step includes: first adding calcium chloride or calcium hydroxide to the wastewater to react with the wastewater to destroy the complexing effect of HEDP-Cu. The coagulation precipitation treatment step includes using alkaline substances such as calcium hydroxide, sodium hydroxide or lime to adjust the pH of the wastewater to 11.5-13.5, then adding PAM, then naturally precipitating, and filtering the supernatant through sand filtration. The present invention avoids the problems of high treatment cost and complex operation of the existing method, the used reagents are easy to obtain, the price is low, and the method is easier to promote.

[0010] The purpose of the present invention is achieved through the following technical solutions.

[0011] A method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater comprises the following steps:

[0012] Step 1, adding calcium chloride or calcium hydroxide to the copper plating wastewater while stirring, so that the calcium ion concentration in the wastewater reaches 2-8g / L; the wastewater contains a complex HEDP-Cu, HEDP reacts with calcium ions, so that the HEDP-Cu complex state is destroyed to generate HEDP-Ca, and the copper ions become free at this time, thereby breaking the complex and obtaining a solution containing free copper ions;

[0013] Step 2: Using calcium hydroxide, sodium hydroxide or lime, the pH value of the solution containing free copper ions is adjusted to alkaline to obtain a solution containing copper hydroxide;

[0014] Step 3: Add 8% PAM by mass to the copper hydroxide solution, with the amount added being 15-20 ml per liter of water; after natural precipitation, filter with sand to complete the wastewater treatment.

[0015] The stirring reaction time in step 1 is 10 min.

[0016] The step 2 of adjusting the pH to alkaline is adjusting the pH to 11.5-13.5.

[0017] The natural sedimentation time in step 3 is 10 minutes.

[0018] Step 3: Sand filtration speed is 9m / h.

[0019] Beneficial Effects

[0020] 1. The present invention uses calcium chloride to break the complex. The calcium chloride reacts with HEDP to release free copper ions, which can effectively destroy the HDPE-copper complex system.

[0021] 2. The present invention adopts the addition of PAM to improve the precipitation of the reaction system, which can achieve rapid and effective separation of mud and water.

[0022] 3. The treatment method of the present invention has the advantages of being simple, economical and having a high removal rate. The total copper and total phosphorus content of the wastewater after treatment meets the discharge standard of a centralized electroplating wastewater treatment plant, that is, total copper ≤0.5 mg / L, and total phosphorus ≤1.0 mg / L. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the embodiments.

[0024] Embodiment 1: Specific embodiment:

[0026] Taking the environmentally friendly HEDP cyanide-free alkaline copper plating wastewater of a certain enterprise as an example, the implementation process of the wastewater treatment method provided by the present invention is described in detail.

[0027] (1) Take 1L of environmentally friendly HEDP cyanide-free alkaline copper plating wastewater from a certain enterprise, with a total copper concentration of 50.87mg / L and a total phosphorus concentration of 25.17mg / L. Add 8g of calcium chloride and stir for 10min. At this time, white suspended matter appears in the wastewater and is not easy to precipitate.

[0028] (2) Calcium hydroxide was added to adjust the pH to 11.82. The white suspended matter still existed and was not separated.

[0029] (3) Add 18 mL of 8% PAM and stir for 1 min until large alum blooms appear.

[0030] (4) Allow to settle naturally for 10 minutes to separate mud and water, and the supernatant is a colorless, transparent liquid.

[0031] (5) The total copper concentration in the liquid after sand filtration was determined to be 0.365 mg / L, and the total phosphorus concentration was 0.464 mg / L.

[0032] Embodiment 2: Specific embodiment:

[0034] Taking the environmentally friendly HEDP cyanide-free alkaline copper plating wastewater of a certain enterprise as an example, the implementation process of the wastewater treatment method provided by the present invention is described in detail.

[0035] (1) Take 1L of environmentally friendly HEDP cyanide-free alkaline copper plating wastewater from a certain enterprise, with a total copper concentration of 21.97 mg / L and a total phosphorus concentration of 38.24 mg / L, add 5g of calcium chloride and stir for 10 minutes. The wastewater changes from light blue to milky white, and white suspended matter appears.

[0036] (2) Calcium hydroxide was added to adjust the pH to 13.42, and wastewater containing white suspended matter was obtained. The water color changed from light blue to transparent.

[0037] (3) Add 18 mL of 8% PAM and stir for 1 min until large alum blooms appear.

[0038] (4) The alum flocs were precipitated naturally for 10 minutes, and the supernatant was a colorless transparent liquid.

[0039] (5) The total copper concentration of the wastewater after sand filtration was 0.423 mg / L, and the total phosphorus concentration was 0.95 mg / L.

[0040] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater, characterized in that: The steps include: Step 1, adding calcium chloride or calcium hydroxide to the copper plating wastewater while stirring, so that the calcium ion concentration in the wastewater reaches 2-8g / L, the wastewater contains a complex HEDP-Cu, HEDP reacts with calcium ions, so that the HEDP-Cu complex state is destroyed to generate HEDP-Ca, at which time the copper ions become free, thereby breaking the complex and obtaining a solution containing free copper ions; Step 2: Using calcium hydroxide, sodium hydroxide or lime, the pH value of the solution containing free copper ions is adjusted to alkaline to obtain a solution containing copper hydroxide; Step 3: Add 8% PAM by mass to the copper hydroxide solution, with the amount added being 15-20 ml per liter of water; after natural precipitation, filter with sand to complete the wastewater treatment.

2. A method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater, characterized in that: The stirring reaction time in step 1 is 10 min.

3. A method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater, characterized in that: The step 2 of adjusting the pH to alkaline is adjusting the pH to 11.5-13.

5.

4. A method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater, characterized in that: The natural sedimentation time in step 3 is 10 minutes.

5. A method for treating environmentally friendly HEDP cyanide-free alkaline copper plating wastewater, characterized in that: Step 3: Sand filtration speed is 9m / h.