Study On Treatment Of Vitamin C Wastewater With Periodically Reversing Electro-coagulation

The pharmaceutical wastewater has complicated, and high toxicity, including various organic pollutants with high concentrations. It will cause severe pollution to water environment and harmful to human healthy directly or indirectly, if discharge without treatment. Treating the pharmaceutical wastewater by electrochemical methods has some significant advantages, such as small floor space for its equipment, low cost, simple to operate and automation, which has attracted widespread attention. But the high energy consumption and liable blunt on anode limited its application. In order to solve these problems, this research was focused on treatment of vitamin C (VC) wastewater with periodically reversing electro-coagulation. The various factors affecting removal efficiency for simulation VC wastewater were investigated and the mechanism was also studied. On this basis, the VC actual wastewater was treated in the laboratory to verify the feasibility of the method.The experiment results involved simulate VC wastewater showed that reaction voltage, electrolyte concentration, speed stirring, plate distance, initial pH value, concentration of Vitamin C and response time had different levels of impact on treating effect. The optimal reaction condition was shown below:reaction voltage was 12 V, electrolyte concentration was 0.02 mol/L, speed stirring was 500 r/min, the distance of electrodes plate was 0.3 cm, initial pH value was 3, concentration of VC was 600 mg/L and response time was 60 min. Under this condition, the removal ratio of CODCr and VC was 95% and 99%, respectively.The mechanism of electro-coagulation treating simulated VC wastewater with Fe/Al periodically reversing was studied. The solution was screened before and after the reaction by the UV-Vis spectrophotometer. The flocs were studied by XRD and FT-IR. The surface of electrodes plate was screened by microscopy. The concentration of metal irons was also detected. The results revealed that the flocculation of metal ions, electric floating, electrolysis oxidization and deoxidization were the main mechanism in electro-coagulation treating pharmaceutical wastewater. Among these effects the flocculation of metal ions was most significant, contributing about 80%. The contribution rate of electric floating and electrolysis oxidization and deoxidization were 18% and 2%, respectively. Using periodically reversing was able to relief plate passivation effectively and protect to the electrode partly.At last, the actual VC wastewater was treated by periodically reversing electro-coagulation. The CODCr and VC of the wastewater were close to 5000 mg/L and 300 mg/L. The results showed that the removal ratio of COD and VC are 26.90% and 86.76%, respectively and the color of wastewater was from brown to colorless.The work has proved that for the treatment of pharmaceutical wastewater, periodically reversing electro-coagulation is a feasible method.