Selective Conversion of Ammonium to Nitrous Oxide in a Bioelectrochemical System

Recently, bioelectrochemical systems (BESs) have emerged as promising alternatives for nitrogen removal from ammonium-rich wastewaters. However, these systems often produce nitrite (NO2-) and nitrate (NO3-) as intermediates, with complete conversion to N2 rarely achieved. Incomplete denitrification may lead to the unintended accumulation of nitrous oxide (N2O), a potent greenhouse gas with valuable applications in various industries, including its use as an oxidizing agent in the selective oxidation of hydrocarbons, as a potent inhalation anesthetic, as a fuel oxidizer in rocket engines and also as food preservative.Given these applications, the potential for producing N2O from ammonium-rich industrial wastewaters represents a sustainable approach. However, the generation of N2O from ammonium in BESs remains underexplored; with existing research primarily focusing on its generation during nitrate reduction. Since nitrogen in wastewater is predominantly in the form of NH4+, nitrification is necessary prior to denitrification. This study aims to evaluate the performance of a single-chamber BES for producing N2O from NH4+ under anodic polarization conditions by coupling partial nitrification to partial denitrification. It explores the electrochemical mechanisms and microbial interactions that facilitate this transformation, highlighting the potential environmental benefits of harnessing N2O production.