Study On Nitrogen, Phosphate Removal Of Aerobic Granular Sludge And Granular Sludge Membrane Bioreactor

For developing high performance, cost saving continuable wastewater treatment technology and exploring simultaneous organics, nitrogen and phosphate removal mechanism of aerobic granular sludge, a series of continuous experiments and batch tests was carried out to investigate the organics, nitrogen, phosphate removal performances and simultaneous nitrification, denitrification and phosphate removal characteristics, mechanism and effect factors in anaerobic-aerobic granular sludge sequencing batch reactor (GSBR), continuous granular sludge membrane bioreactor (CGMBR) and sequencing batch granular sludge membrane bioreactor (SBGMBR). Moreover, the variation of aerobic granular sludge properties and membrane fouling characteristics were paid more attention in CGMBR and SBGMBR.GSBR had been stably operated for 261d, and it showed good organics, nitrogen and phosphate removal performances and the ability to withstand shock loadings. TOC, ammonium nitrogen, total nitrogen and phosphate removal efficiencies were higher than 80%, 93%, 60% and 85% respectively. During anaerobic period, organic substrate was mostly absorbed and stored as intracellular polymer PHB companied by phosphate release and glycogen degradation, and nitrogen and phosphate were removed via intracellular storage polymer PHB driven simultaneous nitrification denitrification and phosphate removal during successive aerobic period. Further batch tests revealed that the activity of denitrifying phosphate accumulating organisms was about 27.87% of the activity of total denitrifying organisms, and 57.44% of the activity of total phosphate accumulating organisms. Moreover, batch tests results indicated ammonium and total nitrogen removal efficiencies decreased with influent C:N decreased, but phosphate removal efficiencies remained up to 98%.The nitrate nitrogen addition concentration higher than 40mg/L would influence nitrogen and phosphate removal performances in GSBR. The higher sludge phosphate content was unfavorable to simultaneous nitrogen and phosphate removal and the intracellular storage polymer utilization, results showed that the sludge phosphate content should be controlled between 2.82%~4.66%. Good nitrogen, phosphate removal efficiencies would be obtained in GSBR when pH value was between 6.14~8.20.CGMBR had been stably operated for 71d, and TOC, ammonium and total nitrogen removal efficiencies of CGMBR were 85%~92%,85.4%~99.7%和41.7%~78.4% respectively. Granular morphology of sludge in CGMBR was the base to obtain good simultaneous nitrification and denitrification(SND) performances and granular sludge with diameter larger than 0.18mm remained 52%~60% in CGMBR. The variation of sludge surface charge, settleability and extracellular polymeric substances(EPS) was monitored during operation, and wet density, water content and metal element content of different size sludge in CGMBR were compared. The influence of sludge mixed liquor filterability and soluble microbial products (SMP) on membrane fouling and membrane effluent quality was also discussed. Results revealed that cake layer had 77.8% of contribution to the total membrane fouling resistance. Compared the size distribution, surface charge, specific resistance to filtration(SRF) and EPS of cake layer sludge with mixed...