CN-121974530-A - Circuit board wastewater heavy metal emission reduction and sludge reduction treatment process method

Abstract

The invention discloses a treatment process method for reducing heavy metal emission and sludge in circuit board wastewater. The invention provides a layered precipitation strategy of acid, alkali and sulfur, which comprises the steps of firstly carrying out acid precipitation on alkaline organic wastewater by utilizing acid wastewater to recover printing ink slag, then carrying out stripping treatment on cuprammonium wastewater by utilizing alkaline conditions to precipitate high-purity copper hydroxide, and finally carrying out deep precipitation on residual complex heavy metals by utilizing excessive sulfides in a pretreatment stage, and simultaneously further recovering copper resources in a comprehensive water tank by coprecipitation of copper hydroxide and copper sulfide. Classification treatment of sludge produced in each process, namely synergic pyrogenic treatment of printing ink sludge, biochemical residual sludge and copper sulfide/nickel sludge, and selective acid dissolution of copper hydroxide sludge to prepare copper sulfate. Lime, ferrous sulfate and polyaluminium sulfate are not used in the whole process. The invention realizes the extreme utilization of the medicament, reduces the sludge by more than 50 percent, and improves the valuable metal recycling value by 3-5 times.

Inventors

• Gong Tianchang
• GONG YOUCHENG
• LIU SINUO

Assignees

• 深圳达人环保有限公司

Dates

Publication Date

20260505

Application Date

20260331

Claims (8)

1. 1. A process method for reducing heavy metal emission and sludge in circuit board wastewater is characterized by comprising the steps of carrying out quality separation treatment and layered precipitation according to the addition sequence of acid, alkali and sulfur, and comprising the following steps: firstly, acid separating alkaline organic wastewater by utilizing acid wastewater, and removing and recycling printing ink residues; Then, carrying out stripping treatment on the copper ammonia wastewater by utilizing alkaline conditions, precipitating and recycling copper hydroxide; And finally, deeply precipitating residual complex heavy metals by utilizing excessive sulfides in the pretreatment stage, and simultaneously, further recovering copper resources in a comprehensive water tank through copper hydroxide and copper sulfide coprecipitation.
2. 2. The process according to claim 1, characterized in that it comprises the following steps: S1, separating and collecting cyanide-containing wastewater, copper ammonia wastewater, nickel-containing wastewater, EDTA wastewater, developing wastewater, membrane stripping wastewater, acid wastewater and comprehensive wastewater; s2, quality-separating pretreatment: ① Adding the developing wastewater and the membrane removing wastewater into the acidic wastewater until the pH value is less than 5, filtering to obtain printing ink residues, and removing the filtrate into a comprehensive water tank; ② Adding alkali into the copper ammonia wastewater until the pH value is more than or equal to 11, stripping, absorbing ammonia gas, filtering to obtain copper hydroxide sludge, and removing filtrate into a comprehensive water tank; ③ Acidifying and stripping the cyanide-containing wastewater until the pH value is less than or equal to 3, absorbing waste gas alkali liquor, and removing filtrate into a comprehensive water tank; ④ Adding sodium sulfide into the nickel-containing wastewater for reaction, filtering, wherein the adding amount of the sodium sulfide is 1.1-2.0 times of the molar concentration of nickel ions, obtaining nickel sulfide filter residues, and removing the filtrate into a comprehensive water tank; ⑤ Adjusting the pH of EDTA wastewater to 7-9, adding sodium sulfide for reaction, filtering, and adding sodium sulfide with the addition amount of 1.5-2.5 times of the molar concentration of copper ions to obtain copper sulfide filter residues, wherein the filtrate is sent to a comprehensive water tank; S3, comprehensive precipitation, namely collecting each filtrate of the S2 into a comprehensive water tank, adjusting the pH to 7-8, carrying out deep precipitation by utilizing excessive sulfides in the S2 ④ and the S2 ⑤, simultaneously generating copper hydroxide and copper sulfide precipitate by residual copper ions in the comprehensive wastewater, and filtering to obtain copper hydroxide/copper sulfide mixed sludge; And S4, biochemical treatment, namely sequentially feeding the filtrate S3 into an anaerobic tank and an aerobic tank for treatment, refluxing the nitrified liquid of the aerobic tank to the anaerobic tank, wherein the reflux ratio is 100% -300%, and discharging the precipitated effluent after reaching the standard.
3. 3. The process of claim 2, wherein the ammonia gas is absorbed with water to form ammonia water in step ② of S2.
4. 4. The process according to claim 2, wherein the reaction pH in step ④ is controlled to 6-8.
5. 5. The process according to claim 2, wherein the EDTA wastewater in step ⑤ is pH-adjusted to 7-9 with acid or alkali prior to the reaction of sodium sulfide.
6. 6. The process of claim 2, wherein the deep precipitation in S3 is performed with excess sulfide in S2 ④ and S2 ⑤ without additional sulfide addition.
7. 7. The process of claim 2, wherein the anaerobic tank in S4 utilizes sulfate reducing bacteria to reduce sulfate to form S 2- , which forms sulfide precipitate with residual heavy metals.
8. 8. The process of claim 2, wherein lime, ferrous sulfate, and polymeric aluminum are not used in the overall process.

Description

Circuit board wastewater heavy metal emission reduction and sludge reduction treatment process method Technical Field The invention relates to the technical field of wastewater treatment, in particular to a process method for reducing heavy metal emission and sludge in circuit board wastewater. Background The production process of the circuit board (PCB) involves wet processes such as development, etching, copper deposition, electroplating and the like, and generates complex wastewater containing pollutants such as heavy metals (copper and nickel), ammonia nitrogen, CODcr, complexing agents and the like. The conventional treatment process has the following problems: 1. The waste of the agent is serious, when the ink is leached, a large amount of sulfuric acid is used for neutralizing sodium carbonate instead of truly precipitating the ink, and when heavy metals are precipitated, a large amount of low-efficiency agents such as lime, ferrous sulfate, polyaluminium sulfate and the like are used, so that a large amount of low-value mixed sludge is generated. 2. The sludge value is low, various sludge is mixed, valuable metals are diluted, recycling recovery is difficult, and the disposal cost is high. 3. And the flow is split, each pretreatment unit independently operates, the cooperative optimization is lacked, and the utilization efficiency of the medicament is low. 4. Potential safety hazards are that high salt supersaturation causes system scaling and mud collection hardening, casualties are often caused by frequent cleaning of mud collection at irregular intervals, and the potential safety hazards become industry hidden pain. Disclosure of Invention The invention aims to provide a process method for reducing heavy metal emission and sludge in circuit board wastewater, which aims to solve the problems of high medicament consumption, high sludge yield, difficult recovery of valuable metals, potential safety hazards of structure scaling and the like in the prior art. The invention provides a quality-dividing treatment and layering precipitation strategy of' acid, alkali and sulfur, which realizes the extreme utilization of the medicament and the high-value recycling of sludge. 1. Acid-separating ink by acid waste water And directly adding alkaline organic wastewater such as development, film stripping and the like into the acidic wastewater, neutralizing alkalinity by using waste acid, and separating out ink residues. Compared with the traditional single acid precipitation, the method saves more than 50% of sulfuric acid, and simultaneously avoids the operation problem caused by the escape of a large amount of CO 2. The synergistic mechanism realizes the clean production concept of treating waste with waste. 2. Post-alkali precipitation of high purity copper hydroxide using alkaline conditions Adding alkali into copper ammonia wastewater (such as etching cleaning water) until the pH value is more than or equal to 11, stripping ammonia gas, and absorbing the ammonia gas with water to generate ammonia water for recycling. Copper ions in the blown-off wastewater are precipitated in a copper hydroxide form, and the copper content of the obtained copper hydroxide sludge dry basis can reach more than 95% because of source purity (no interference of other metal ions), so that the copper hydroxide sludge dry basis can be directly dried and sold or dissolved by sulfuric acid to prepare electroplating-grade copper sulfate, and high-value resource recovery is realized. 3. Re-Sulfur-deep precipitation with excess sulfide And (3) adding excessive sodium sulfide during pretreatment of the nickel-containing wastewater and EDTA wastewater, continuously playing a role in a comprehensive water tank, and deeply precipitating residual complex heavy metals in the form of copper sulfide/nickel. Meanwhile, the mixed comprehensive wastewater still contains copper ions with a certain concentration, and the mixed comprehensive wastewater reacts with excessive sulfide in the pretreatment stage under the condition of pH 7-8 to generate copper sulfide precipitate, and forms coprecipitation with copper hydroxide in the wastewater, so that copper resources are further recovered. The drug relay mechanism does not need additional drug administration, and realizes the extreme utilization of sulfide drugs. 4. Clay residue classification and directional recycling The printing ink slag and the biochemical excess sludge are organic matters and are combustible, and the printing ink slag and the biochemical excess sludge are treated by a fire method in cooperation with copper sulfide/nickel sludge, so that a smelting plant can simultaneously recover copper and utilize the heat value of the organic matters. Copper hydroxide sludge (from copper ammonia wastewater) is prepared by high purity, selective acid dissolution, and small amount of filtered residue is returned to the pyrogenic process. Copper hydroxide/copper sulfide mixed sludge (from compreh