Study On Treatment Of Organic Wastewater Using Three-Dimensional Electrode-Fenton Reagent

Potato starch wastewater is a kind of sewage with high concentration of organic pollutants, resulting in serious environmental pollutions. Three-dimensional electrode was used to further degrade the potato starch wastewater without the compressed air after coagulation. The degradation of several simulated phenol compounds was studied simultaneously.The thesis consists of four parts.In Chapter 1, the quality and the pollution characteristics of potato starch wastewater were described. Its pretreatments of coagulation and the characteristics of three-dimensional electrode were introduced. The reaction mechanism, the classifications and the applications of three-dimensional electrode were reviewed.In Chapter 2, the three-dimensional electrode technique was used to further degrade the potato starch wastewater without the compressed air after coagulation. The effect of Fenton reagent, the plate material, the diameter of columnar activated carbon, the ratio of activated carbon and special insulating materials, voltage, the amount of activated carbon, properties of activated carbon, dynamic–static experiment, the initial concentration of wastewater and the sand filtration on the removal rate of COD were investigated under certain conditions. The experimental results show that the three-dimensional electrode was used to treat the starch wastewater of initial COD 1142 mg·L^-1 with a Ti/SnO₂ electrode as two anodes and a graphite plate as a cathode using wooden columnar activated carbon with 5mm diameter as particle electrodes. The wastewater was electrolyzed for 180min. Thereafter the electrolytic solution was filtered through the sand of 2mm size. Its COD can be reduced to 188mg·L^-1. The water quality discharged is close to the secondary standard of state (Integrated Discharge Standard of Wastewater, GB 8978^-1996) under the conditions of the voltage 20.0V,pH 2.0 with the 4:1 ratio of activated carbon to insulator in electrolytic cell.In Chapter 3, the reaction mechanism of Fenton reagent and the concentration of H₂O₂ and Fe²⁺ on Fenton reaction were discussed using three-dimensional electrode. The influence of the three-dimensional electrode-Fenton and UV-TiO₂-Fenton methods on the COD removal rate of starch wastewater was compared.In Chapter 4, the treatment techniques and the development of phenol wastewater was briefly summarized. The degradation of several phenols in simulated wastewater was investigated with three-dimensional electrode-Fenton reagent by the COD removal rate and the UV-Vis spectrum. The results showed that the removal rate of phenol compounds is higher with three-dimensional electrode-Fenton reagent. Their COD removal rate of simulated wastewater is in the order, polyphenol > binary phenol > phenol.