Adsorption Of Cu From Printed Circuit Boards Wastewater By SR Bacteria

Since 1980, electronic industry has quickly developed. The need for printed circuit boards (PCB) has increased and the yield has raised. So the quantity of wastewater in the production has also increased. The technology for producing printed circuit boards is very complicated and the components of wastewater are complicated. The main pollutants, which can danger environment and human being, are heavy metals. Cu is very common in PCB wastewater with higher concentration and different forms. The main problems of present technique for removing Cu from the wastewater are not reaching the national emission standard, producing too much solid waste with heavy metal, possible secondary contamination, high disposal cost and so on.biosorption has many advantages in the disposal of electroplating wastewater with heavy metals, especially for the wastewater with lower concentration of heavy metal, with high removal rates, rapid speed and low run cost. But the application of biosorption for the disposal of printed circuit boards wastewater has not been reported. So in our research work, the main factors that affected the adsorption of Cu from actual printed circuit boards wastewater by SR bacteria were systemically studied. The isothermal equation of the adsorption process was found and the possible adsorption mechanism was given in terms of the test resultsby Transmission electron microscope (TEM) and Scanning electron microscope - silvering X-ray microanalysis. Experiment results were following:1. The adsorption processes were by SR bacteria were fast and could reach equability in 30 min for acidic compounding wastewater, alkaline compounding wastewater, non-complex copper wastewater and removed membrane wastewater by using SR bacteria.2. The suitable quantity of SR bacteria into the water was 6. 3g/L (dry weight) , 4. 36g/L (dry weight) , 0. 33g/L (dry weight) and 0. 25g/L (dry weight) for acidic compounding wastewater, alkaline compoundingwastewater, non-complex copper wastewater and removed membrane wastewater.3. pH was important for the adsorption process in non-complex copper wastewater. The most suitable PH was about 3.7.4. Adsorption temperature had no significant effect on the adsorption results for acidic and alkaline compounding wastewater. The suitable temperatures were is 30 癈 for non-complex copper wastewater and 20-30 癈 for removed membrane waste water.5. SR bacteria adsorbing Cu in acidic compounding waste water could get 80% desorption by 1% H2SO4 in 10 min.6. Freundlich adsorption isothermal was met by the adsorption process in acidic compounding wastewater, in which the K was 20.62 and 1/n was 0.41. Langmuir adsorption isothermal was met by the adsorption process in alkaline compounding wastewater, in which the Qo was 99mg/g and the b was 0. 53.7. The possible mechanism for removing Cu by SR bacteria adsorption from the PCB wastewater was extracellular deposition or cell surface adsorption.In concluding, the main innovation of this work is: 1. Main factors affecting the adsorption process of Cu by SR bacteriawas systematically examined using actual wastewater.2. Adsorption isothermals of the adsorption process were found and the possible mechanism was given as extracellular deposition or cell surface adsorption.