The Denitrification Dynamics of Modified UCT Step Feed Enhanced Biological Nutrients Removal Process

Batch experiments are conducted to investigate the denitrification prosperities,denitrification dynamics and pH variation with municipal wastewater,supernatants of sludge hydrolyzed acidification,acetic sodium,methanol,ethanol and glucose as electron donors as well as nitrate as electron acceptor under T=(15±1)℃.The results show that the maximum specific denitrification rate and specific organic compounds utilization rate,which is 4.13mg/h and 29.8mg/h,respectively,were attained when acetic sodium is used as the electron donor,whereas the lowest denitrification potential was also observed.As for supernatants of sludge hydrolyzed acidification,its denitrification performance is nearly as same as acetic sodium.Furthermore,denitrification bacteria can adapt to methanol and ethanol until a period of sludge acclimations,so these two electron donors could not be used as soon as it needed to improve the denitrification efficiency.As for glucose,there is a "ρ(NO_x^--N) reduction stop platform" during 10-120mins of reaction process,after glucose molecules decomposing into small molecules organisms the denitrification could go on successfully,so glycoside is the rate-limiting step of denitrification with glucose as the electron donor.Besides,pH indicates the denitrification characteristics of different electron donors with heterotrophy anoxic yields of 0.68-0.73.