Optimal design and evaluation of electrocatalytic reactors with nano-MnOx/Ti membrane electrode for wastewater treatment

Nano-MnOx loaded porous Ti membrane was employed as anode to constitute electrocatalytic reactor (ECR), electrocatalytic membrane reactor (ECMR), fixed-bed electrocatalytic reactor (FBER) for synthetic phenolic wastewater treatment. The effects of operating voltage, residence time and reaction stage were investigated. Results showed that FBER under the voltage of 2.0 V and residence time of 10.5 min displayed the better electrochemical degradation performance. When the concentration of phenolic wastewater was 188 mg/L, the remove rate of phenol and COD obtained from FBER were up to 73.6% and 66.0% for one-stage FBER, 96.0% and 89.3% for eight-stage FBER, respectively. The apparent reaction rate constant of FBER raised from 0.167 min−1 to 0.389 min−1 with the increase of FBER stages from one to eights. Further, the energy consumption of FBER with one stage and eight stages were 0.25 and 0.75 kWh/kg COD, respectively. ECMR and FBER with a high electrocatalytic reaction efficiency were ascribed to the synergy effect of electrocatalytic oxidation and enhance mass diffusion. Moreover, the uniformity of fluid distribution in FBER leaded to a high diffusion coefficient. Furthermore, a pilot-scale membrane bioreactor (MBR)-FBER plant was developed to the treatment of landfill leachate (COD 22,500 mg/L and NH4+-N 207 mg/L). The total COD and NH4+-N removal rate reached 95.6% and 84.5%, respectively. The pilot-scale MBR-FBER plant exhibits a great application potential in the industrial wastewater treatment.