Nguyen Van Khanh, Park Younghyun, Yang Heechun, Yu Jaecheul, Lee Taeho
Department of Civil and Environmental Engineering, Pusan National University, Pusan, 609-735, Republic of Korea.
J Ind Microbiol Biotechnol. 2016 Jun;43(6):783-93. doi: 10.1007/s10295-016-1762-6. Epub 2016 Mar 28.
Recently, bioelectrochemical systems have been demonstrated as advantageous for denitrification. Here, we investigated the nitrate reduction rate and bacterial community on cathodes at different cathode potentials [-300, -500, -700, and -900 mV vs. standard hydrogen electrode (SHE)] in a two-chamber microbial electrochemical denitrification system and effects of sulfate, a common nitrate co-contaminant, on denitrification efficiency. The results indicated that the highest nitrate reduction rates (3.5 mg L(-1) days(-1)) were obtained at a cathode potential of -700 mV, regardless of sulfate presence, while a lower rate was observed at a more negative cathode potential (-900 mV). Notably, although sulfate ions generally inhibited nitrate reduction, this effect was absent at a cathode potential of -700 mV. Polymerase chain reaction-denaturing gradient gel electrophoresis revealed that bacterial communities on the graphite-felt cathode were significantly affected by the cathode potential change and sulfate presence. Shinella-like and Alicycliphilus-like bacterial species were exclusively observed on cathodes in reactors without sulfate. Ochrobactrum-like and Sinorhizobium-like bacterial species, which persisted at different cathode potentials irrespective of sulfate presence, were shown to contribute to bioelectrochemical denitrification. This study suggested that a cathode potential of around -700 mV versus SHE would ensure optimal nitrate reduction rate and counteract inhibitory effects of sulfate. Additionally, sulfate presence considerably affects denitrification efficiency and microbial community of microbial electrochemical denitrification systems.
最近，生物电化学系统已被证明在反硝化方面具有优势。在此，我们研究了两室微生物电化学反硝化系统中不同阴极电位[-300、-500、-700和-900 mV对标准氢电极（SHE）]下阴极上的硝酸盐还原率和细菌群落，以及常见的硝酸盐共污染物硫酸盐对反硝化效率的影响。结果表明，无论是否存在硫酸盐，在阴极电位为-700 mV时均可获得最高的硝酸盐还原率（3.5 mg L⁻¹ d⁻¹），而在更负的阴极电位（-900 mV）下观察到的还原率较低。值得注意的是，虽然硫酸根离子通常会抑制硝酸盐还原，但在阴极电位为-700 mV时这种抑制作用不存在。聚合酶链反应-变性梯度凝胶电泳显示，石墨毡阴极上的细菌群落受到阴极电位变化和硫酸盐存在的显著影响。仅在无硫酸盐的反应器阴极上观察到类申氏菌属和类嗜环烷菌属细菌物种。无论是否存在硫酸盐，在不同阴极电位下均能持续存在的类慢生根瘤菌属和类中华根瘤菌属细菌物种被证明对生物电化学反硝化有贡献。本研究表明，相对于SHE约-700 mV的阴极电位可确保最佳的硝酸盐还原率，并抵消硫酸盐的抑制作用。此外，硫酸盐的存在会显著影响微生物电化学反硝化系统的反硝化效率和微生物群落。
