The Start-up Of UBF-anammox Reactors And Study Of Functional Bacteria

Anammox(anaerobic ammonia oxidation)has been a promising biological nitrogen removal process because of its high-efficient and energy-saving features.The optimization of start-up will promote the applicationof anammox process.In this study,two anammox processes were performed in two identical lab-scale UBF reactors with different substrate concentrations,their nitrogen removal rates,sludge characterization,and microbial community.Furthermore,anammox activity test of a denitrifying bacterial strain and its effect on anammox sludge were conducted.When the start-up process was finished,the effect of sodium bicarbonate and para aminobenzoic acid on the nitrogen removal performance of the reactor was performed.The results showed that successful start-up of anammox process for R1 and R2 took 60 days and 98 days to achieve,respectively.R2 had a longer start-up period and slower granulation process compared with R1.What’s more,sludge from R2 showed in red while sludge from R1 showed in reddish brown.Difference of activity between R1 and R2 were not obviously observed until day 69.During activity elevation period,the NRR(nitrogen removal rate)of R2 was always above R1,R1 and R2 achieved the maximum NRRs of 1.213 and 1.684 kg/(m3·d)under the NLRs(nitrogen load rates)of 1.924 and 2.502 kg/(m3·d),respectively.These results showed that after going through a higher NLR acclimation process during start-up period,stronger resistant capability against high impact nitrogen load and greater anammox activity were obtained by R2.Through the comparison of microbial community between the two reactors,it was found that R1 possessed more species.Planctomycetes,Chloroflexis,Proteobacteria and Bacteroidetes were the dominant phyla on day 10,89 and 178.The community composition of R1 was close to R2.The majority of Planctomycetes were anammox bacteria,on day 178,R2(43.9%)had a higher proportion of anammox bacteria than R1(38.2%).The primary effect experiment of sodium bicarbonate and para aminobenzoic acid manifested: suitable addition of sodium bicarbonate(0.8g/Land 1.2g/L)and para aminobenzoic acid(0.025mg/L)could promote the nitrogen removal performance of anammox reactor.Excess para aminobenzoic acid inhabited anammox activity.And under the experiment condition of the study,there was no synergistic effect between sodium bicarbonate and para aminobenzoic acidon anammox process.