Recovery of electron and carbon source from agricultural waste corncob by microbial electrochemical system to enhance wastewater denitrification

The denitrification process in wastewater treatment plants (WWTPs) is limited by insufficient carbon sources. Agricultural waste corncob was investigated for its feasibility as a low-cost carbon source for efficient denitrification. The results showed that the corncob as the carbon source exhibited a similar denitrification rate (19.01 +/- 0.03 gNO3--N/ m3d) to that of the traditional carbon source sodium acetate (19.13 +/- 0.37 gNO3--N/m3d). When filling corncob into a microbial electrochemical system (MES) three-dimensional anode, the release of corncob carbon sources was well controlled with an improved denitrification rate (20.73 +/- 0.20 gNO3 --N/m3d). Carbon source and electron recovered from corncob led to autotrophic denitrification and heterotrophic denitrification occurred in the MES cathode, which synergistically improved the denitrification performance of the system. The proposed strategy for enhanced nitrogen removal by autotrophic coupled with heterotrophic denitrification using agricultural waste corncob as the sole carbon source opened up an attractive route for low-cost and safe deep nitrogen removal in WWTPs and resource utilization for agricultural waste corncob.

Automated summary

The feasibility of using agricultural waste corncob as a low-cost carbon source for efficient denitrification in wastewater treatment plants (WWTPs) was investigated. Results showed that the denitrification rate of corncob was similar to that of traditional carbon source sodium acetate. When corncob was used in a microbial electrochemical system (MES), the release of corncob carbon sources was well controlled, resulting in improved denitrification rate. The combination of autotrophic and heterotrophic denitrification using corncob as the sole carbon source offers a promising and cost-effective approach for nitrogen removal in WWTPs.