The Research Of The Treatment For Zinc Wastewater Under The Condition Of High COD In Organic Silicon Industry

A large amount of heavy metal wastewater containing high concentration of organic compounds would be produced in organic silicon production process; This kind of highly toxic wastewater without effective treatment will have a significant impact on the ecological environment and human health.This study is about the treatment experiment of Zinc wastewater containing high concentration of organic compounds produced in some organicsilicon enterprise. Respectively compares the effect of “Neutralization precipitation+Microfiltration”、“Photocatalytic +Neutralization-precipitation+Microfiltration”、“Electro-coagulation method”、“Electrocoagulation+ Neutralization-precipitation+Microfiltration”、“Microfiltration + Electrocoagulation +Neutralization-precipitation+Microfiltration”, in order to look for the best method and the parameters of best solution.Research shows that:(1)use the “Neutralization-precipitation +Microfiltration” method to deal with the wastewater, in the condition of pH was 10, the treated wasterwater COD decreased from 2000mg/L to 789mg/L, removal rate was 60.55%; Zinc ion concentration decreased from 40mg/L to 0.624mg/L, removal rate was 98.44%.(2)use the “Photocatalytic +Neutralization-precipitation+Microfiltration” method to deal with the wasterwater, control the initial pH value for 4, the photocatalytic time was 2h, the ozone dosage was 60mg/min. the treated wasterwater COD decreased from 2000mg/L to 531mg/L, removal rate was 73.45%; the Zinc ion concentration decreased from 40mg/L to 0.513mg/L, removal rate was 98.72%.(3)use the “Electro-coagulation method ” to deal with the wastewater, control the current density was 7.0 A/m2, electro-coagulation time was 45 min, plate spacing was 2cm. the treated wasterwater COD decreased from 2000mg/L to 454mg/L, removal rate was 77.30%; the Zinc ion concentration decreased from 40mg/L to 6.081mg/L, removal rate was 84.80%.(4)use the “Electro-coagulation+Neutralization-precipitation +Microfiltration” method to deal with the wastewater, the COD in the treated wastewater decreased from 2000mg/L to 342mg/L, removal rate was 82.90%; the Zinc ion concentration could decreased from 40mg/L to 0.162mg/L, removal rate was 99.59%.(5)use the “Microfiltration+Electrocoagulation+Neutralization-precipitation+Microfiltration” method to deal with the wastewater,the COD in the treated wastewater decreased from 2000mg/L to 265mg/L, removal rate was 86.75%; the Zinc ion concentration decreased from 40mg/L to 0.034mg/L, removal rate was 99.91%.Through the comparison of the above five kinds of wastewater treatment plan Although zinc ion concentration can up to standard by“Neutralization+Microfiltration” “Photocatalytic+Neutralization-precipitation+Microfiltration”、 “Electric- coagulation + Neutralization-precipitation+Microfiltration” and “Microfiltration+Electric-coagulation +Neutralization-precipitation+ Microfiltration”,but under the method of “ Neutralization +Microfiltration” or “Photocatalytic+Neutralization-precipitation+Microfiltration”, the COD or Zn2+ concentration in the outlet wastewater is still high, and the Zn2+ concentration in the outlet wastewater,which the removal rate reach more than 99.5%, which is much lower under the method of “Electric-coagulation+Neutralizationprecipitation+Microfiltration” or “ Microfiltration+Electric-coagulation+Neutralizationprecipitation +Microfiltration, the COD is also much lower than before. For the complex actual wastewater, we should choose “Electric-coagulation+ Neutralizationprecipitation+Microfiltration” or “Microfiltration+Electric-coagulation+Neutralizationprecipitation+Microfiltration” as the best method in order to ensure the low concentration of Zn2 +.