Study of a combined sulfur autotrophic with proton-exchange membrane electrodialytic denitrification technology: Sulfate control and pH balance

• Published in: Bioresource technology 2011-12, Vol.102 (23), p.10803-10809
• Main Authors: Wan, Dongjin, Liu, Huijuan, Liu, Ruiping, Qu, Jiuhui
• Format: Article
• Language: English
• Subjects: Autotrophic denitrification; Autotrophic Processes; Biological and medical sciences; Biotechnology - methods; Denitrification; Effluents; Electrochemistry - methods; Equipment Design; Fundamental and applied biological sciences. Psychology; Hydrogen; Hydrogen-Ion Concentration; Kinetics; Membranes; Nitrate removal; Nitrates - chemistry; Nitrites; Nitrites - chemistry; Nitrogen - chemistry; Optimization; pH balance; Proton-exchange membrane electrodialysis; Protons; Sulfates; Sulfur; Sulfur - chemistry; Time Factors; Water Pollutants, Chemical - analysis; Water Purification - methods
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2011.08.132

► A novel combined denitrification system was developed and tested. ► The system consisted of sulfur and bio-electrodialysis part. ► The combined process could achieve pH balance thus avoiding nitrite accumulation. ► The sulfate generation could be controlled by HRT of sulfur part. ► The removal rate of bio-electrodialysis part was controlled by applied current. A novel combined system established for nitrate removal from aqueous solution consisted of two parts: sulfur autotrophic denitrification and bio-electrochemical denitrification based on proton-exchange membrane electrodialysis (PEMED). The system was operated at various hydraulic retention times (HRT) and current intensities. Its optimum operation condition was also determined. The combined process had pH adjustment thus generating less nitrite than PEMED process. The denitrification rate of sulfur autotrophic part was dependent on HRT, while shorter HRT could reduce the sulfate generated by the sulfur autotrophic process. The denitrification rate of PEMED process depended on the applied current. For 32±1mg-N/L nitrate in influent, the optimum operation parameters of combined process were: HRT 2h; applied current 350mA. The combined reactor could achieve 95.8% nitrate removal without nitrite accumulation, the pH of effluent kept neutral and the sulfate of effluent was 202.1mg/L, lower than the drinking water standard in China.