Quick Cultivate Of Denitrified Granular Sludge And Its Characteristics By Using Fluctuation Operation Strategy

In this research,the formation mechanism of denitrification granular sludge under different conditions was explored by changing the controllable conditions?organic load,nitrate nitrogen and hydraulic retention time?in the process of denitrification granular sludge culture.According to the different operating conditions,we propose a quick start-up denitrification granular sludge operation plan.Under the semi-starvation fluctuation organic load condition,it takes 20 d for the formation of denitrifying granular sludge.R3 reactor after 43 days of operation,when the influent COD and NO₃^--N increased to 1500 mg·L^-1 and 300 mg·L^-1 respectively,COD and NO₃^--N removal rate in R3 reactor were still remain above 95%.Compared with the R1reactor,R3 reactor could promote the microbial diversity and denitrification granular sludge had better denitrification performance.By synthesizing the experimental data obtained,the formation mechanism of denitrifying granular sludge in R3 reactor was explored.Under fluctuating nitrate nitrogen conditions,it takes 22 d for the formation of denitrified granular sludge.After 58 days of R2 and R3 reactor operation,when the influent COD and NO₃^--N concentration were increased to 2250 mg·L^-1 and 450 mg·L^-1respectively,the COD and NO₃^--N removal rates remained above 95%.In contrast to the R1 reactor,the fluctuating nitrate nitrogen in R3 reactor could stimulate microbial secretion more AHLs,change the amount of EPS,and stimulate the more protein secretion,accelerating denitrification granular sludge formation.Under fluctuating hydraulic retention time,the formation of denitrifying granular sludge only takes 14 days.R2 reactor after 6 days of operation,the AHLs concentration rapidly increased to 1.2 mg·g^-1 MLVSS.This condition could change the microbial structure and enhance the microbial diversity,making denitrification granular sludge has better denitrification performance.By synthesizing the experimental data obtained,the formation mechanism of denitrifying granular sludge in R2 reactor was explored.