Cleaning waste liquid classification and handling way in the PCB cleaning production
At present, the rapid development of the electronics industry, PCB electronics industry as one of the foundations. It is an annual rate of 10-20% annually. Thus becoming one of the important industries in the electronics industry, but its complex manufacturing process produces many waste and wastewater. On the one hand the PCB plant need to maintain wastewater discharge standards; on the other hand, we should consider the savings on water costs. So as to protect our environment, to avoid causing serious pollution to the environment, so the wastewater treatment plant is re-focusing of the PCB environmental protection.
NO.1PCB cleaning waste classification
PCB waste is divided into waste water and waste liquid:
1.Grinding plate clean brush water (waste water mill plate)
2.General cleaning water
4. Complex wastewater
5 copper plating rinse water
6 nickel-containing wash water
7 wastewater containing cyanide
8.Acidic waste, waste oil, chemical copper waste,
9. Expansion waste, waste permanganate etching solution
10. Alkaline waste, waste activated, microetch waste, etc.
NO.2 The main pollutant treatment technology
PBC main wastewater : 1.copper 2.COD 3 ammonia 4.pH, cyanide, nickel, etc.
The main treatment of pollutants – Cu removal
PCB wastewater containing copper mainly divided into two forms:
1, ionic copper – methods: alkali precipitation and ion exchange.
2, a copper complexing and chelating :
1) masking changes, destruction of the structure of the ligand; releasing copper ions
2) directly competing ions and Cu precipitate formed.
The main treatment of pollutants – COD removal
Tuomo mainly developing waste ink caused by COD.
Common treatment methods:
- Acid precipitation – coagulation and sedimentation
- Acid precipitation – chemical oxidation;
- Acid precipitation – activated carbon adsorption method;
- Acid analysis – biological treatment;
Acid out processing:
PH between 2 ~ 4, ink can form colloidal insolubles, place COD solid-liquid separation to achieve.
Main pollutant treatment technology, ammonia nitrogen removal
High ammonia solubility, stable chemical properties, physical and chemical method is difficult to remove.
1.Chlorine oxidation (principle of chlorine tap water to fold point). Chlorine oxidation, difficult to handle, and expensive.
2.Biochemical method: denitrifying bacteria dissolved ammonia nitrogen into nitrite, nitrate form; The cost of the biological nitrification is low.
Main pollutant treatment technology – Ni removal
Nickel ion processing method:
Ni2 + + 2 OH – > Ni (OH) 2 left Ksp = 10-15.2, pH > 9.5, the standard 1.0 mg/L.
The processing of complexing nickel:
Once in electroless nickel plating, phosphorous acid, phosphorous acid, phosphate can form complex nickel. Inorganic complexing agent, a simple chemical oxidation can undermine its structure.
Removal of main pollutant treatment technology – CN
The traditional alkali method:
Incomplete oxidation period:CN－+ClO－-+H2O→CNCl－+2OH－
Complete oxidation period: CNO－+ 3OCl－+H2O→2CO2+N2+3Cl－+2OH－