Research On The Rheological Characterization And Variation Regulation Of The Anaerobic Digested Sludge

As an effective measures to make sludge stabilization and resource recovery,sludge anaerobic digestion technology has derived a lot of attention in the treatment and disposal of sludge and the application. Civil sludge is non- newtonian fluid and its rheological properties in play a key role in the process of anaerobic digestion, affects the mixing, mass transfer,pumping and transportation, etc. Therefore, through the Research on variation of rheological properties of sludge in anaerobic digestion, the anaerobic digestion can have a more comprehensive understanding, the development of anaerobic digestion process play a certain guiding significance.In this article, firstly, rheological characteristics of concentrated raw sludge and digested sludge was analyzed, especially the effect on the rheological properties of the sludge caused by the variation of EPS content and the change of sludge particle size of sludge before and after digestion,and discussed the thixotropy and calculation of theory stirring power of sludge before and after digestion process in three different digestion temperature 20 ℃, 35 ℃and 55 ℃ Then starting the anaerobic digestion reaction device measuring p H/ORP and variation regulation of rheological properties in anaerobic digestion process and the torque variation in the process of mixing through torque sensor, and calculating the mixing power consumption. Finally, the conclusions as follows:(1) Compared with concentrated sludge, elevating temperature caused the reduction of shear stress of digested sludge to a larger extent,and the results show that,in the pipeline digested sludge have greater advantages in enhancing liquidity by elevating temperature than concentrated sludge,meaning that digested sludge is more suitable in terms of pipe flow transportation.(2) The flow index of concentrated sludge is less than that of the digested sludge, and viscosity index is greater than that of digested sludge,showing digested sludge is less close to Non-newtonian fluid.(3) After anaerobic digestion, the average particle size of sludge reduced from 100 um to50um,and the space between molecules is more narrow,but molecular floc reduced significantly due to the shrinking of organic matter content.Also the amount of EPS reduced,mainly because fixation EPS transformed into soluble EPS.And the thixotropic loop of digested sludge is bigger than that of concentrated sludge The higher the temperature, the more obvious the difference of thixotropic loop.(4) As temperature rise,sludge viscosity reduced,liquidity enhanced and the stirring power also reduced. Under laboratory conditions in anaerobic digestion the stirring power is9.9211 W(5) The viscosity of sludge is relatively stable in the anaerobic digestion reactor, Its limit viscosity stability in 300 m Pa?s,The viscosity can be used in characterization of anaerobic digestion index of stable running...