Study On Pulsed Current Electrocoagulation For Restaurant Wastewater Treatment

With the development of the economy and the improvement of living standard, the quantity of restaurant wastewater in the urban soars recently. Restaurant wastewater has been threatening the environment. It is very important to treat the restaurant wastewater properly in dealing with the urban wastewater. Some ways has been used to treat restaurant wastewater, such as coagulation, the activated-sludge processes, electrocoagulation and so on. There are second pollutions in the process of coagulation. Both biological ways and bubble separation are also not perfectly adapted to treating restaurant wastewater because of the complicated process and inconvenience in administration. Electrocoagulation is a environmental friendly technology of water treatment. It is simple and suitable for restaurant wastewater treatment, but it is not widely used in restaurant wastewater treatment in practice because it is expensive.It is hard to get a resolution to the serious environmental pollution problems caused by restaurants wastewater, which is not due to the unmanageability of restaurant wastewater but the difficulty to find a suitable and economic way to treat it. Electrocoagulation can adapt to characteristics of restaurant wastewater, but it isn't put into use in fact because operation of electrocoagulation is expensive. The process of electrocoagulation was improved by applying a pulsed current on electrodes in order to eliminate the problems.By choosing appropriate electrodes and changing influencing factors, static experiments and electrochemical experiments were designed to estimate whether pulsed current electrocoagulation is better than direct current electrocoagulation or not in the efficiency and the capacity of preventing the aluminum anodic from passivating. Electrolysis current half-life, open circuit potential after polarization, removal efficiency for COD_Cr and oil were measured. The experimental results of pulsed current compared to direct current electrocoagulation indicate that pulsed currentelectrocoagulation can eliminate the anodic passive films effectively and improve current efficiency.The related data in the continuous dynamic experiment showed that pulsed current electrocoagulation could not only eliminate aluminum anodic films but also engender the cooperative effect of electrocoagulation and electroflotation and that treatment efficiency improved greatly. To the same removal efficiency of CODcr and oil, pulsed current electrocoagulation could reduce energy consumption about 30% in contrast to direct current electrocoagulation. The optimum parameters of pulsed current electrocoagulation under the experimental conditions were found to be: 6.8A/cm2 for current density, 0.15Hz for frequency, 0.7 for duty cycle respectively.Process of the aluminum anodic passivation was researched by electrochemical measure, some ways were suggested to eliminate the aluminum anodic passivation, such as changing the electrode polarity timely, using double-aluminum electrode.