Development And Application Of A Pulse Three-dimensional Electrode Reactor In Citric Acid Wastewater Treatment

Advanced treatment with refractory industrial wastewater is a difficultproblem in the field of wastewater treatment. In order to discover a high-efficiencyand low-energy method for advanced treatment with refractory industrialwastewater, three-dimensional electrode oxidation method was used to treat withsecondary effluent of citric acid wastewater in this paper. The operatingparameters of three-dimensional electrode reactor were optimized, afterwards, TiSn and Sb were used as loaded catalysts on filling material to improve reactorCOD removal, in addition, pulse power supply was used to decrease reactor energyconsumption, and the influence of reactor structure on reactor COD removal wasalso studied. Based on these researches, a pilot-scale reactor was set up, and thelong running stability and energy consumption of the reactor were investigated.The COD removal of three-dimensional electrode reactor was affected bycurrent density, hydraulic retention time (HRT) and pH, and the optimizedoperating parameters determined by single factor experiments are as following:current density=5mA/cm2, HRT=1h, pH=4.5-5.5. In regard to filling material, itwas proved that loading Ti Sn and Sb on filling material could improve reactorCOD removal from40%to65%by increasing the oxygen evolution potential ofthe filling material and producing more·OH. Meanwhile, in order to decrease thereactor energy consumption, pulse power supply was used, and the energyconsumption could decrease from146kWh/kg COD to65kWh/kg COD withalmost the same COD removal when pulse power supply parameters were asfollowing: duty cycle=0.4and period=25s. Reactor structure was also proved tobe an influence factor on reactor COD removal, and the optimized operatingparameters are as following: electrode spacing=5cm, material filling ratio=70%,and the electrode shape is plate electrode.Wastewater degradation pathway had also been studied, and it was proved thathumic acid-like, fulvic acid-like, solube microbial products-like and tryptophan-like protein in wastewater had a good degradation in electrochemical reaction process, which was the pathway of COD removal. Meanwhile, it was discovered thatbenzene derivatives had a better degradation in electrochemical reaction processthan long-chain molecules.Based on the above researches, a pilot-scale three-dimensional electrodereactor with pulse was set up， which was running continuously in40days, andCOD of the effluent could keep below80mg/L when COD of the inflow was100-180mg/L, and the average COD removal was52%, and the reactor energyconsumption could keep in about60kWh/kg COD.