Affiliation:
1. School of Environmental Science and Engineering Nanjing Tech University Nanjing Jiangsu P. R. China
2. State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University Nanjing Jiangsu P. R. China
Abstract
AbstractTo enhance the removal of nitrate nitrogen (NO3−‐N) in groundwater with a low C/N ratio, electrocatalytic reduction of NO3−‐N has received extensive attention since its electrons can be directly produced in situ while simultaneously providing a clean electronic donor of hydrogen for denitrifying bacteria. In this study, Ti/CNT/CuPd bimetallic catalytic electrodes with different copper‐palladium (CuPd) ratios were prepared by electrodeposition onto carbon nanotube (CNT) using titanium (Ti) plates. The results showed that the NO3−‐N conversion rate by Ti/CNT/Cu5‐Pd5 electrode was the highest (53.60%) compared with other CuPd electrode ratios because of the combined role of the copper's high NO3−‐N catalytic activity and the palladium's high N2 selectivity. A new type of electrode biofilm reactor (EBR) with Ti/CNT/Cu5‐Pd5 cathode, biochar substrate was constructed to explore the removal ability of NO3−‐N in simulated low C/N groundwater. When the influent NO3−‐N concentration was 30 mg/L, under the condition of a 30 mA electronic current and hydraulic retention time (HRT) of 12 h, the removal rate of NO3−‐N could reach as high as 78.1 ± 1.2%, and the N2 conversion rate was 99.7%. The horizontal distribution of microbial communities in EBR showed that the denitrification capacity was significantly improved through the electrochemical catalytic reduction of the Ti/CNT/Cu5‐Pd5 cathode and the supply of the hydrogen electron donor to autotrophic denitrogenerating microbes such as Anaerobacillus, Thauera, and Hydrophaga. This study provides a new bimetallic catalytic cathode to enhance the removal of NO3−‐N in groundwater with a low C/N ratio.Practitioner Points
The Cu5Pd5/CNTs/Ti electrode is beneficial to the adsorption and reduction of NO3−‐N to N2.
The production of hydrogen electron donors by cathode promoted nitrogen degradation.
Activated electrodes together with denitrifying microorganisms contributed to the improved N removal rate.
Funder
National Natural Science Foundation of China
Natural Science Foundation of Jiangsu Province
Subject
Water Science and Technology,Ecological Modeling,Waste Management and Disposal,Pollution,Environmental Chemistry