Study On The Stable Operation Characteristics Of The USB Reactor With Denitrification Granular Sludge

Granular sludge technology is a novel biological wastewater treatment technology,which has the advantages of good settling performance,high microbial holding capacity,high treatment efficiency compared with conventional biological wastewater treatment technology.However,denitrifying granular sludge was discovered frequently unstabitily phenomenon(e.g.,granule fragmentation,floating and wash-out)during the long-term operation,and those problems hindered the wide application of granular sludge technology.This paper employed higher hydraulic shear force condition(25.7/s and 14.5/s)for obtain high stability granular sludge in view of the above problems.And utilized the high stability granular sludge as seed sludge for research the effect of the operational environmental factors(hydraulic shear force and typical coexisting pollutants)on the shear stability,removal stability and microbial community structure of granular sludge during the reactor operation process,and determine granular sludge reactor stable operation strategy,guided the long-term stable operation of reactor.The major conclusions are as follows:1)Under high hydraulic shear condition(25.7/s),the required time of complete granulationwas only 56 days,and the shear sensitivity(Kss)of mature granular sludge was only 0.000045.Under the lower hydraulic shear condition of 14.5/s,granulation time is about 70 days,Kss is 0.0052;the USBL reactor has stronger nitrate nitrogen removal stability.The dominant microorganisms in the mature granular sludge were mainly micro rods,and the dominant species were Methyloversatilis(46.07%)and Azospira(11.50%).2)The optimum hydraulic shear rate range of operation of two kinds of high and low shear stability of denitrifying granular sludge were: 35.145~44.808/s 20.336~30.504/s,respectively,both of two Kss sludges have less fluctuation in this interval The most stable nitrate nitrogen removal intervals were 25.1~37.5/s and 20.3~22.4/s,respectively.The number of microbial population in the granular sludge decreased gradually,and the strong resistance ability of the microorganism to the hydraulic shear was a new dominant species.3)Nitrite concentration below 300mg/L in the degradation process of sludge have certain inhibition,concentration was increased to 450 mg/L,the removal of sludge to promote,the existence of the sludge degradation stability have beneficial effects.The high concentration of perchlorate(900mg/L)have a significant effect on the sludge.This paper will enhance mutual understanding of granular sludge reactor for long-term stable operation,and provide theoretical and technical support for the generalize and application of stable granular sludge technology.