Electrical stimulation enhanced denitrification of nitrite-dependent anaerobic methane-oxidizing bacteria

As a process utilizing methane as the sole electron source to reduce nitrite, nitrite-dependent anaerobic methane-oxidizing (n-damo) shows high potential to be applied in energy-efficient wastewater treatment. However, the metabolism of n-damo bacteria is far too low for practical application. In this study, bioelectrical reactor (BER) was used to enhance the metabolism. The nitrite removal rate was accelerated under applied electric field. The best stimulating effect was obtained at 1 V applied with the denitrification rate increased to 1.8 fold compared to conventional n-damo process. The enhancement of nitrite consumption was consistent well with the acceleration of methane depletion, further confirmed the electrical stimulation of n-damo process. However, the enhancement could only be realized under continuous electrical exposure mode, rather than intermittent mode. The above results demonstrated that electrical stimulation could lead to an enhanced denitrification of n-damo bacteria.