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

Zhao, Y., Miao, J., Ren, X., Wu, G.
International journal of environmental science and technology 2018 v.15 no.2 pp. 461-470
Thauera, biofuels, chemical oxygen demand, denitrification, denitrifying microorganisms, energy recovery, ethanol, glucose, methanol, microbial communities, nitrites, nitrogen, nitrous oxide, organic carbon, sodium acetate, wastewater
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.