The Biological Aerated Filter And Sulfur Ceramsite Autotrophic Denitrification Advanced Treatment Of Nitrogen In Wastewater

The pollution of water evironment and the shortage of water resources drive the researches in the reuse of wastewater and applications of advanced treatment. The secondary effluent of municipal wastewater is a good potential water source due to its stable quality and large quantity. But researchers are challenged by the nitrogen removal with low carbon source in the secondary effluen of municipal wastewater. At present, the advanced treatment of nitrogen with low organic carbon is a challenging work. Traditional heterotrophic denitrification needs to add extra carbon source which not only requires additional cost but also cause secondly pollution. In our study, a new advanced treatment of nitrogen process combined biological aerated filter and sulfur ceramsite autotrophic denitrification (SCAD) is proposed. The influence of temperature on BAF and SCAD is studied. The experiment that the related operation parameters of alkalinity (in the form of NaHCO3), flow rate is also studied.The ammonia nitrogen removal efficiency is above 95% when the temperature is above 15℃and decrease to 55%-70%, 65%-80% when the temperature drops to 10℃, 5℃respectivly. The nitrate removal efficiency is above 98% at 5℃-35℃when the DO concentration in influent is 2-4 mg/L. Low temperature and high DO concentration do not hinder the nitrate removal efficiency. The TN removal efficiency is above 90% by the combination of BAF and SCAD due to high NH4+-N and NO3--N removal efficiency when the temperature is above 15℃. The nitrification at low temperature is a limiting factor for TN removal. The COD,Turnity and UV254 in the effluent of SCAD are higher than those in influent especially at high temperature. The obtained ratio of sulphate to nitrate is 7.6-9.5 which is a little higher than the theoretical value. And the sulphate concentration in effluent of SCAD increases as the temperature drops down.High dosage of NaHCO3 can improve the denitrification rate but alkalinity ?saturation'occurs with more than 400 mg/L NaHCO3. The nitrite accumulation occurs with theoretical alkalinity although nitrate removal efficiency is above 98%. The empty bed contact time (EBCT) has a more pronounced effect on the ammonia nitrogen removal efficiency than nitrate, and thus TN concentration rises up due to the high levelof NH4+-N concentration. Our findings challenge the classic view that low temperature and high DO concentration often restrain the autotrophic denitrification removal efficiency and suggest that high nitrate removal is still achieved at low temperature. It shows great significance especislly for the nitrate removal at low temperature in cold aeras.