Effect of organic carbon on the production of biofuel nitrous oxide during the denitrification process

The carbon source plays an important role in denitrification for nitrogen removal from wastewater. In this study, the denitrification performance and nitrous oxide (N2O) generation in four sequencing batch reactors (SBRs) fed with methanol, ethanol, sodium acetate and glucose were investigated. The maximum N2O generation was achieved when glucose was used as the carbon source, with a N2O conversion ratio of 56%. The high conversion ratio was contributed from the organic carbon of glucose and the glucose-acclimated denitrifiers. The nitrite accumulation and N2O generation during denitrification with glucose as the carbon source increased with increasing chemical oxygen demand to nitrogen ratios in the range of 2-8. The microbial community and their relative abundances varied greatly in the four reactors, and a low abundance of Thauera was found in the glucose-fed SBR, which might contribute to the greater N2O production. Practical strategies for N2O generation from the denitrification process using glucose as the carbon source were proposed so as to achieve energy recovery from nitrogen in wastewater.