Study On High Efficiency Treatment Of Coking Wastewater By Integrating Photoelectric Catalysis In Fuel Cells

Coking wastewater is generated during coking process,which usually contains high concentrations toxic organic pollutants such as ammonia,cyanide,polycyclic aromatic hydrocarbons and nitrogen-containing heterocyclic compounds.It belongs to toxic industrial wastewater.Very often high-cost biological methods and advanced treatment are necessary to meet the standard.Since wastewater can be used as a source of bio-electricity generation,research on microbial fuel cells?MFC?has received increasing attention.In addition,abundant solar energy and inexpensive semiconductor materials can constitute the photocatalytic fuel cell?PFC?.PFC is also considered an environmentally-friendly technology that can treat the wastewater while generating electricity.This study about integrating MFC and PFC can increase the efficiency of the treatment of coking wastewater and reduce the costs.ZnIn₂S₄/BiVO₄ photocatalytic materials with different ratios were successfully prepared by hydrothermal method,and the optimal compositional doping ratio was studied.The instruments of SEM,CV,UV-Vis and XPS were used to characterize the catalyst and catalytic electrodes,results shows that ZnIn₂S₄/BiVO₄has good photo electrochemical catalytic performance.In reactors of MFC integrated with PFC,and PFC with persulfate?PS?,efficient removal of COD and ammonia nitrogen?NH₄⁺-N?from coking wastewater were achieved.The COD content decreased from average2896 mg/L in the influent to an average of 263 mg/L?91%removal?.The effluent of MFC was further treated in PFC with Fe as the anode and ZnIn₂S₄/BiVO₄ as the photocathode.In the PFC,pH 4 and PS concentration of 30 mM is the best condition for wastewater treatment.The COD concentration of the effluent is less than 50 mg/L,and the NH₄⁺-N concentration is less than 5 mg/L.The electricity production was increased with PS addition.The concentration of NH₄⁺-N after MFC treatment increased,but can be reduced to<5 mg/L after the final oxidation in the PFC/PS reactor at optimal conditions.The results indicate that integration of MFC,PFC and PFC is efficient in the process of treating coking wastewater.