丝状菌污泥致密过程的强化条件研究

利用强化条件促使丝状菌污泥致密,是控制丝状菌污泥膨胀的一种新途径.分别采用提高溶解氧、加大表面流体流速、增加进水钙离子浓度、延长饥饿时间等方法从污泥的沉降性能方面探讨了丝状菌污泥在何时致密及怎样致密等问题.结果表明,加大表面气体流速能够短期内改善污泥的沉降性能,并且形成丝状菌颗粒污泥,污泥的SVI从膨胀时的800 mL/g降低为350 mL/g,但长期作用不明显,SVI在保持了一段时间较低值后,再次升高到800 mL/g以上.增加进水钙离子浓度能够通过形成簇状污泥群落来提高污泥的沉降性能,SVI值逐渐降低到300 mL/g,但是没有形成丝状菌颗粒.提高溶解氧和延长曝气时间在改善污泥沉降性能和丝状菌颗粒化两方面皆无明显效果,污泥的SVI并没有降低.另外,通过研究网眼椭圆度与污泥SVI的关系,发现具有高椭圆度(椭圆度O约为1.5)的成簇生长丝状菌菌群,能够改善污泥沉降性能.浸泡实验发现酸性条件对菌丝的凝聚具有破坏作用,碱性条件和二价阳离子对其影响不显著.

Investigation on Enhanced Conditions for the Densification of Filamentous Sludge

A new approach was investigated for controlling sludge bulking by using enhanced conditions for densification of filamentous sludge. Several methods, including elevated dissolved oxygen, increased superficial velocity, elevated calcium concentration, extended starvation time, have been employed to reveal when and how filamentous sludge could be denser in terms of settleability. It showed that increased superficial velocity improved the settleability and event triggered filamentous granulation in a short term, i.e.,sludge volumetric index(SVI) decreased from 800 mL/g to 350 mL/g, and it became less effective in a long term, as the SVI increased to approximately 800 mL/g after a short period of stable operation. Elevated calcium concentration also improved the settleability by clustering the mycelium of filamentous microorganisms,and then SVI decreased to 300 mL/g gradually, but no granulation was observed. However, negligible changes were observed by elevated dissolved oxygen or extended starvation time, as the decrease of SVI value could not be significantly observed. Additionally, relationship between ovality of filamentous mesh and sludge volumetric index was also examined. It was found that the clustered growth that brought about high ovality(approximately 1.5) could improve the settleability. Additionally, acidic condition may damage the mycelium aggregation, and alkaline condition and divalent cation concentration were insignificant for mycelium aggregation.