The composition of PCB wastewater is complex and difficult to deal with, how to effectively remove harmful substances, reduce environmental pollution, is currently China's PCB industry is facing a major task.
PCB wastewater is a kind of waste water, which is a kind of waste water in printing industry and circuit board factory. Now, the world annual production of hazardous chemical waste amounted to 300 million to 4 tons, of which the ecological harm, and the earth is the most widely spread of persistent organic pollutants (POP), in addition, PCB wastewater into washing wastewater, ink wastewater, compounding wastewater, concentrated acid waste, concentrated alkali waste liquid. Printed circuit board production water consumption, many kinds of pollutants, complex components. According to the characteristics of wastewater from different PCB manufacturers, the reasonable classification, collection and disposal is the key to ensure the wastewater treatment standards.
For PCB in industry wastewater treatment, chemical method (chemical precipitation, ion exchange method, electrolysis), physical method (all kinds of decantation and filtration, electrodialysis, reverse osmosis, etc.) method is the chemical pollutants in wastewater into the easy separation of the state (solid or gaseous) the physical method, is the concentration of pollutants in the wastewater or separated easily separated state from wastewater, the wastewater reach the discharge standard. There are several methods used at home and abroad.
One, decanting method
Decanting method is actually the filtration method is a kind of PCB panel industry wastewater treatment method in physics. Deburring machine discharge containing copper scraps flushing water decanter after treatment, can be filtered to remove copper scraps. The decanter filtered water can be cleaned with water burr machine.
Two, chemical method
Chemical methods include oxidation-reduction and chemical precipitation. Oxidation reduction method is the use of oxidants or reducing agent to convert harmful substances into harmless substances or easy precipitation, precipitation of substances. Oxidation reduction method is often used in a circuit board wastewater containing cyanide and chromium containing wastewater, see back.
The chemical precipitation method is to select one or several chemical agents to convert harmful substances into easily separated precipitates or precipitates. There are a variety of chemical wastewater treatment of a circuit board used, such as NaOH, CaO, Ca (OH) 2, Na2S, CaS, Na2CO3, PFS, PAC, PAM, FeSO4, FeCl3, ISX, precipitating agent can bring heavy metal ions into the sediment, then precipitated by inclined plate pool, sand filter, PE filter and press, the solid-liquid separation.
Three, chemical precipitation - ion exchange method
It is difficult to deal with the high concentration waste water treatment by chemical precipitation step by step. The chemical precipitation method was used to treat the waste water of high concentration circuit board, so as to reduce the content of heavy metal ions to 5mg/L.
Four, electrolytic ion exchange method
In the process of wastewater treatment in PCB board industry, the treatment of high concentration wastewater by electrolysis can reduce the content of heavy metal ions. But the shortcomings are: electrolysis treatment of high concentration of heavy metal ions effectively, lower concentration, current efficiency decreased significantly, decreased significantly; power consumption, promotion difficult; processing of single metal electrolysis only. Electrolysis - ion exchange method is copper plating, etching waste liquid, for other waste water, but also with other methods.
Five, chemical method membrane filtration method
PCB board industry wastewater treatment by chemical pretreatment, so that the harmful substances precipitated particles can be filtered (>0.1 mm diameter), and then filtered through the membrane filtration device, you can achieve emission standards.
Six, gas condensation - electro filtration method
PCB board industry wastewater treatment method, gas - electric condensation filter method is developed in the United States in 80s without the addition of chemical reagents a novel wastewater treatment method, belonging to a physical method to treat the wastewater of printed circuit board. Includes three parts, the first part is the ionized gas generator, air is sucked into the generator, can change the chemical structure of ionization magnetic field, magnetic ions and nitrogen ion becomes highly activated, with the introduction of gas jet device in the wastewater, the wastewater of the oxidized gold metal ions and organic matter and other harmful substances accumulation together, the second part is easily removed by filtration; electrolyte filter, filtering to remove the first generation of agglomerate material; the third part is the high speed ultraviolet irradiation device, ultraviolet radiation into the water can oxidize organic compounds and chemical complexing agent, reducing CODcr and BOD5. At present, has developed a complete set of integrated equipment can be directly applied.