Study On The Effect Of Extracellular Polymeric Substances On Nitrogen Removal Of Anammox

Anaerobic ammonium oxidation(anammox)is a new type of biological nitrogen removal technology,which directly oxidizes ammonia to nitrogen using nitrite as electron acceptor under anaerobic conditions.The anammox process has been favored by a large number of reaearchers due to its advantages of less oxygen consumption,no additional carbon source and less excess sludge production.Extracellular polymeric substances(EPS)can maintain the stable operation of the reactor,and play an important role in the operation of anammox reactor and nitrogen removal process.The study investigated the characteristics of EPS in anammox reactor and its influence on nitrogen removal by anammox characteristics,in order to provide important technical support for improving the efficiency of anammox.The main research contents are as follows:1)Using long-term freezing(-20 C)anammox sludge storage as the inoculation sludge startup of anammox reactor.During its activity recovery process,it experienced a short stagnation period.After 15 days,the activity was completely recovered and the nitrogen removal load reacthed to 0.617 kg-N/m~3/d,and then increased to 3.06 kg-N/m~3/d after 100 days of operation.This improved that the long-term frozen storage of anammox sludge did not cause the risk of loss of activity.During the logarithmic growth of anammox bacteria,the concentration of EPS increased abruptly,indicating that EPS could positively regulate anammox sludge metabolism and improve anammox activity.During the activity recovery,two kinds of AHLs,C6-HSL and C8-HSL,were detected,which promoted the secretion of EPS,and positively regulated the metabolic activity of anammox bacteria.2)Batch experiments were conducted to investigate the effects of denitrifying sludge and perchlorate granular sludge EPS on nitrogen removal performance of anammox sludge.The results showed that the effect of denitrifying granular sludge on activity of anammox sludge is due to LB-EPS.AHLs were detected in EPS,which was an important factor leading to the increase of nitrogen removal efficiency of anammox,indicating that quorum sensing system played an important role in anammox process.C4-HSL can singly regulate the metabolism of anammox bacteria;C6-HSL could simultaneously regulate the metabolism of anammox bacteria and denitrifying bacteria,and the sensitivity of different microorganisms to C6-HSL was different.C8-HSL had no significant effect on the metabolism of anammox bacteria.3)The anammox reactor successfully started-up by inoculating the mixture of perchlorate granule sludge and anammox sludge,and the nitrogen removal load was 0.56kg-N/m3/d on the 50th day,which proved the reactor was successfully started up.The reactor was operated for 100 days,and the nitrogen removal load reached 2.49 kg-N/m3/d.EPS and AHLs can positively regulate the metabolic behavior of anammox bacteria.During the operation of the reactor,the concentration of EPS in the granular sludge increased rapidly during the logarithmic growth period of anammox bacteria,while C6-HSL and C8-HSL were detected during the operation of reactor,which was similar to the 1)part.With the reactor operation,the anammox bacteria become the dominant bacteria,and the nitrogen removal performance of the reactor was inproved.