Applications Of Electrochemical Methods In Reclaimed Water Disinfection

With the increasing deterioration of environmental pollution, people need more efficient, more economic and clearer pollution removing technologies. As one of the "environmental friendly technology", electrochemical water disinfection is proved good disinfection effectiveness, having residual disinfection, amenability to automation, versatility and so on, so it attracted many peoples' attention as a "Advanced Oxidation Progress".Based on our past research experience, this thesis are focus on application of electrochemical disinfection on reclaimed water in the laboratory and in the field. Several electrodes were evaluated, according to their disinfection effectiveness, to choose the best; the reaction dynamics on the electrode surface were studied in the reclaimed water; the production of reactive oxidant substance was studied, and its factors; a large-scale electrochemical disinfection reactor was applied in the progress of reclaimed water treatment on-site. The following results are:Electrochemical method produced some kinds of reactive oxidant substances, such as Cl₂, ClO₂, O₃, H₂O₂, ClO₂, OH·and so on, which can kill bacteria effectively. DSA(dimensionally stable anode) was thought the best anode material in the electrochemical disinfection reactor, because of its high surface area, good electrochemical stability and excellent electro-catability. The electro-generated active chlorine was affected largely by electric voltage and electrode plate interval. During the treatment, the pH, ORP and electric conductivity were not changed. The decay rate of reactive oxidant substances was comparable to chlorine decay rate, but much lower than ozone. The results of a large-scale application showed that when the electric voltage was 24 V, electric current density was 10.8mA/cm², the ratio of surface area/volume was 19.2 cm²/m³, and the HRT was 37s, the residual chlorine of the effluent was 0.67mg/L, the total colony units was 28 per liter, the total coliform units was 1 per liter, the NH₃-N removing ratio was 16.3%, and the electric energy consumption was 0.095kWh/m³. The pH, ORP and electric conductivity of the effluent did not change significantly.