Treatment of nitrate-contaminated groundwater by heterotrophic denitrification coupled with electro-autotrophic denitrifying packed bed reactor

• Published in: Biochemical engineering journal Vol. 134; pp. 12 - 21
• Main Authors: Peng, Tong, Feng, Chuanping, Hu, Weiwu, Chen, Nan, He, Qiaochong, Dong, Shanshan, Xu, Yaxian, Gao, Yu, Li, Miao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2018
• Subjects: Bio-electrochemical reactor; Denitrification; Hydrogenotrophic; Material conversions; Mixotrophic; Denitrification; Mixotrophic; Bio-electrochemical reactor; Hydrogenotrophic; Material conversions
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2018.02.016

[Display omitted] •Current influence on microbes is eliminated in the bio-electrochemical reactor.•High performance denitrification of the mixotrophic process is achieved.•Effective material conversion is promoted by microbial ecological interaction. A mixotrophic system consisting of heterotrophic and autotrophic denitrification (HAD) is a reliable system to enhance the denitrification performance of individual systems. In this study, a novel heterotrophic denitrification coupled with an electro-autotrophic denitrifying packed bed reactor (HEAD-PBR) was developed for the treatment of nitrate-contaminated groundwater. Because of the combination of electrochemical and biological denitrification processes in series, electrochemical inhibition of microorganisms was eliminated, and sufficient hydrogen was supplied safely. The efficiency of HEAD-PBR was evaluated using synthetic groundwater (containing 50 and 25 mg N/L of NO3−) at different hydraulic retention times. A high nitrate removal efficiency (∼99%) was achieved, the electrolysis, heterotrophic denitrification, and autotrophic denitrification were responsible for 15.6%–23.4%, 44.6%–68.4% and 15.7%–31.7% of nitrate removal, respectively. This effective material conversion can be attributed to microbial ecological interactions such as sufficient utilization of sawdust and proper consumption of hydrogen, oxygen, and ammonia. The HEAD-PBR was found to be an efficient reactor system with high treatment capacity, but without accumulation of byproduct in effluent. Thus, HEAD-PBR is a promising reactor configuration for nitrate removal and implementation of HAD technology.