Study On Aerobic Granular Sludge In A Continuous Flow Dynamic Membrane Bioreactor

Aerobic granular sludge is a promising wastewater treatment technology,however, the effluents of the granular sludge reactor are often instable, resulting from the washout of mixed liquor suspended solids (MLSS). Therefore, in this study, the aerobic granulation technology was combined with the dynamic membrane bioreactor for developing a sustainable technology to continuous flow dynamic membrane bioreactor combined with aerobic granular sludge. This paper includes following research work:Firstly, the granulation of aerobic granular sludge and decontamination features were studied in four different influent modes: Mode I 6h sequencing operation, Mode II, 6h sequencing operation + 6h continuous flow operation, Mode III 12h+12h and Mode IV 24h+24h, respectively.The COD removal in four modes varied slightly, and average removal efficiency was above 96%. The results showed that NH₃^-N concentration had significant effects, NH₃^-N average removal efficiency dropped from 95% to 65% and 95% to 75%, during Mode I and Mode IV respectively, when NH₃^-N concentration increased from 30mg/L to 40mg/L. The trend of TN removal rate curve was similar with that of NH₃^-N, but that of TN relatively flat. TP average removal efficiency reached higher than 85% in sequencing operation mode; while, with continuous flow influent modes, TP remove efficiency was poorer, minimum only 60%.Under continuous influent conditions, the organic loading had small influence on COD and NH₃^-N removal efficiency. The average removal rate of TP reached 62%,94% and 76%, respectively at the organic loading of 0.8kgCOD/(m3·d),1.2kgCOD/(m3·d) and 1.6kgCOD/(m3·d). In the dynamic membrane bioreactor zone, the average removal efficiency of COD and TN could both reach 5%, while the highest average removal efficiency of NH₃^-N can reached 15% at COD 600mg/L, NH₃^-N 60mg/L and TN 16.5mg/L.The membrane flux had certain influence on the pollutant removal efficiency. When membrane flux was 30L/(m2·h), there were serious loss of sludge in SBAR zone, and certain increase of sludge in dynamic membrane bioreactor zone, in addition, effluent turbidity significantly increased. Within a certain range, COD removal in different membrane flux varied slightly, and COD average removal efficiency was more than 95%. When membrane flux was 20L/(m2·h), effluent NH₃^-N concentration was below 1.5mg/L. Under low flux conditions(10L/(m²·h)), average removal rate of TN and TP was less than 80% and 70%, respectively.