Development of a novel palm fiber biofilm electrode reactor (PBER) for nitrate-contaminated wastewater treatment: performance and mechanism
A novel palm fiber biofilm electrode reactor (PBER) was developed, and its denitrification mechanism was analyzed by investigating denitrification performance, extracellular polymeric substances (EPS) and microbial community. The results showed that palm fiber was a stable and efficient electrode embedding material. Almost 100% nitrate removal efficiency was achieved at 250 mA/m2 with rarely accumulation of nitrite and ammonium. Moreover, a lower energy consumption of 3.84×10-3 kWh/g NO- 3-N was obtained. It was confirmed that nitrate could be reduced by extracellular electron transfer through fulvic acid-like and humic acid-like substances in EPS. And EPS promoted biofilm stability and microbial activity at optimal current density. Furthermore, the hydrogen autotrophic denitrifying and electroactive bacterium were significantly enriched at 250 mA/m2. This study proposed an efficient BER for nitrate-contaminated wastewater treatment and provided an approach for the evaluation of denitrification mechanism in bioelectrochemical systems.