PCB Technical - Pollutant treatment methods in the PCB production process

Pollutant treatment methods in the PCB production process

During the PCB production process, substances harmful to the environment will be produced. In addition to production capacity, the ability to handle harmful substances is also an important measure of modern factories. Carrying out "green production" is the inevitable way for modern industry. So, how to deal with the harmful substances produced in the PCB production process?

PCB circuit board waste water is divided into cleaning waste water, ink waste water, complexation waste water, concentrated acid waste liquid, concentrated alkali waste liquid and so on. There are many types of waste water pollutants and complex components. The key to ensure that the wastewater treatment meets the standards is to treat the waste water that is targeted at a reasonable quality. PCB circuit board wastewater treatment is mainly divided into chemical method and physical method. Chemical method converts pollutants in wastewater into easily separable state (solid or gaseous), including chemical precipitation method, redox method, ion exchange method, The electrolysis method, etc., the physical method is to enrich the pollutants in the waste water or separate the easily separable state from the waste water to make the waste water meet the discharge standards, mainly including decantation, electrodialysis, and reverse osmosis.

1. Redox method

oxidation-reduction method uses oxidizing or reducing agents to convert harmful substances into harmless substances, which are precipitated and precipitated. The cyanide-containing wastewater and chromium-containing wastewater in the circuit board often use the oxidation-reduction method.

2. Electrolysis

The electrolysis method treats high-concentration circuit board wastewater, which can reduce the content of heavy metal ions, but the electrolysis method is only effective for the treatment of high-concentration heavy metal ions, and consumes a lot of power, which can only treat single metals.

3. Ion exchange method

It is difficult to treat high-concentration wastewater by chemical precipitation, and it is often used in combination with ion exchange. First, chemical precipitation method is used to reduce the content of heavy metal ions to about 5 mg/L, and then ion exchange method is used to reduce heavy metal ions to emission standards.

4. Chemical precipitation

Chemical precipitation method is to select one or several chemical agents to convert harmful substances into easily separated precipitates or precipitates. There are many kinds of chemical agents used in circuit board wastewater treatment, such as NaOH, CaO, Ca(OH)2, Na2S, etc. The precipitant can convert heavy metal ions into sediment, and then pass through the inclined plate sedimentation tank, sand filter, and filter press And so on, so that the solid-liquid separation.

5. Gaseous Condensation-Electric Filtration Method

This novel method consists of three parts. The first part is the ionized gas generator. Air is sucked into the generator, which can make the ionized magnetic field change its chemical structure and become highly activated magnetic oxygen ions and nitrogen ions. The jet device is used to introduce this gas into the wastewater to make The metal ions, organic matter and other harmful substances in the wastewater are oxidized and aggregated into clusters, which are easy to filter and remove. The second part is an electrolyte filter, which filters and removes the agglomerates produced in the first part. The third part is a high-speed ultraviolet irradiation device. The ultraviolet rays can oxidize organic matter and chemical complexing agents in the water, and reduce CODcr and BOD5.