Research On Rapid Cultivation Of Aerobic Granular Sludge And Treatment Of Salinity Wastewater

Aerobic granular sludge technology is a new biological treatment technology in recent years, compared with the conventional activated sludge, the aerobic granular sludge has higher biological activity, dense microbial structure, improved settling properties, higher strength, to keep the reactor higher sludge concentration and biomass, thus is able to withstand the impact of high concentration organic wastewater and toxic substances, it is a research hotspot in biological wastewater treatment area at present. However, the long startup time of aerobic granular system is a major obstacle to its practical application. In addition, the conventional activated sludge system is often not easy to keep stable due to serious loss of biomass in the treatment of high salinity wastewater, while the aerobic granular sludge system may be one of the effective ways to solve the problem. In view of this, this paper explores the feasibility of high salinity wastewater treatment based on the research of rapid startup method and purification performance of aerobic granular sludge.In this experiment, aerobic granular sludge was cultivated by SBR. Investigation showed that only inoculating conventional activated sludge(R1), adding fine soil(R2), dosing small amount of anaerobic granules(R3) as condensation nuclei which all can be cultivated aerobic granular sludge, the required time is 30 days, 21 days, 15 days, the method of adding fine soil and anaerobic granular shortened the formation time. The average particle size of aerobic granular sludge cultivated in 3 reactors is 0.2mm, 0.5mm, 0.8mm; sedimentation velocity is 0.32 cm/s, 0.65 cm/s, 1.02cm/s; water content is 97.6 %, 96.2%, 95.3%; the SOUR is 41.13 mg/(g·h), 45.89 mg/(g·h), 64.12 mg/(g·h) respectively. Granules formed in the test has good settling performance, as the SVI value is between 35~45m L/g. Scanning electron microscope showed that there are many holes inside the particles, using as the transmission channel of nutrients and oxygen, a large number of cocci and bacilli also can be observed, and a small amount of filamentous bacteria. The three reactors all have good removal effect of COD, NH4+-N and TP.The dynamics difference of the three kinds of aerobic granular sludge is studied based on the Michaelis-Menten equation. Research showed that the degradation kinetics equation of the mature aerobic granular sludge in R1, R2, R3 is:Experiments investigate salinity changes on physicochemical properties and microbial purification performance of the granules using mature aerobic granular sludge from R3. The results showed that: under the conditions of less than 1% salinity, the granulars tend to form a hollow interior, but the overall structure is compact, they can still maintain higher microbial activity after adaptation, the removal efficiency of COD and NH4+-N are 90% and 91%, higher than the ordinary sludge of 80% and 82% at the same salinity; Under the 2.5% salinity condition, the particle structure is loose, some disintegrated or broken, which increased effluent SS, and organics removal efficiency begins to decrease; After the salinity increased to 5%, the aerobic granules become dense, particle size increases and stabilize, but the microbial activities have been obviously affected, the activity of the aerobic granular sludge decreased 60%, while the ordinary sludge decreased 70~80%, COD removal efficiency were 70% and 26%, NH4+-N removal efficiency were 85% and 40%, under this condition, the conventional activated sludge was seriously inhibited, whereas the aerobic granular sludge system still has good removal effect of organics.