Treatment method for comprehensive wastewater in circuit board industry

Abstract

The invention discloses a treatment method for comprehensive wastewater in a circuit board industry. The method comprises the following steps: step 1, adding sulfuric acid into the comprehensive wastewater, adjusting the pH to 2.5-3.5, adding ferrous sulfate, and performing a complex breaking reaction; step2, adding NaOH, adjusting the pH to 9.5-10.5 to remove copper ions, then adding a coagulant,performing stirring, performing primary filtration or sedimentation to obtain intermediate wastewater 1, and performing concentration collection on sludge; step 3, adding NaOH into the intermediate wastewater 1, adjusting the pH to 9.5-10.5, and adding sodium sulfide for a secondary copper removing reaction; step 4: adding ferrous sulfate to remove excess sulfur ions; and step 5, adding a coagulant, performing stirring, performing secondary filtration or sedimentation to obtain intermediate wastewater 2, and performing concentration collection on sludge. According to the method disclosed in the invention, copper removing reactions of a sodium hydroxide method and a sodium sulfide method are adopted for sewage treatment, so that a concentration of copper ions in preformed precipitate wateris reduced, metal ion poisoning of bacteria and fungi in subsequent processes is avoided, and the material costs are reduced; and the method has outstanding characteristics of a good environmentally-friendly index and low production costs..

Description

technical field [0001] The invention relates to the field of printed circuit board manufacturing, and more specifically, relates to a comprehensive wastewater treatment method in the circuit board industry. Background technique [0002] Wastewater from the circuit board industry comes from various processing processes of circuit boards. Wastewater from each processing process has different characteristics and can be divided into several categories according to the nature of the waste water, such as recyclable waste water, cyanide-containing waste water, nickel-containing waste water, silver-containing waste water, and acid waste liquid , high organic waste liquid, complex wastewater and comprehensive wastewater, etc. At present, most circuit board companies tend to treat the waste water separately according to the different properties of the waste water. For the waste water with similar pollutants, they can be treated in a centralized manner after being treated separately in...

AI Technical Summary

Problems solved by technology

[0006] The existing technology has the following defects: 1) The amount of sludge generated is large, or the alum flower in the reaction tank is small, so that the fine mud can easily enter the biochemical tank; 2) The content of copper ions in the effluent after filtration or precipitation is relatively high, generally 0.5mg / L, not only the copper ion discharge index exceeds the standard, but also has a greater impact on the biochemical pool; 3) Fenton's reagent is added in excess at one time, and the solution after the Fenton reaction is acidic, and a large amount of NaOH needs to be used to adjust the pH to alkaline. Therefore, the raw materials used in the current technology are more, and the cost is higher; 4) the impact of unreacted sulfide ions on the biochemical pool is also relatively large

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