Characterizing Denitrification Kinetics in Lab Scale Reactors for Longer Time Ethanol Dosage

抄録

Influence of external carbon dosage for balancing denitrification kinetics for heterotrophic organisms is necessary to understand the efficiency of biological nitrogen removal from wastewater. The aim of this study was to evaluate the long term effect of ethanol dosage on heterotrophs. Three experiments were performed for 38 hours with a single dose at 1.2 mgCOD/mgTSS of food to microorganism ratio. We observed that organisms needed at least 20 hours to acclimate to ethanol based on specific denitrification rate (SDNR) and carbon to nitrate (C/N) ratio. However, for multiple dosage of ethanol for 67 hours of contact time showed that SDNR increased by more than five times compared to single dosage. In this case, the C/N ratio and anoxic yield coefficient decreased as N₂O emission increased during multiple times of ethanol addition. The maximum of 4.4% of N₂O emission was observed at C/N ratio of 4.38 mgCOD/mgNO₃-N. It was concluded that higher influent C/N ratio for longer time contact with biomass was responsible for producing N₂O gases which inhibited the yield. Thus, the possibility of using optimal ethanol dose with specific feeding time is critical to estimate the correct carbon requirement for denitrification.