After aeration phase, sludge settling has improved and seen initially 15 to 20 mins, but as high concentration of stalked ciliates are present, the ciliates with sludge is coming to top of the reactor, causing sludge wash out in decant waster. How to control this stalked ciliates conc.? or any other solution?
Sandip, refer to my answer to your former question, where I mismatched SBR and MBR (sorry...)
First be aware of the genera, very often (with urban WW) you will find Epistylis (colonial, rigid stalks) or Carchesium (Vorticella-like cells, colonial also but with contractile stalks). The first one withstand large aeration breaks (aeration stopped more than 2 or 3 hours), the second one, no. So aeration schedule is important. If you get LARGE colonies (i.e. 1000 cells / colony), they appear generally under transient conditions (starting phase, sludges losses or recirculation breakdown - the later case is out of concern here...) If you are not in a transient phase, may be SRT is too low, decrease sludge extraction. As already quoted by formers replies, crawling ciliates - mainly Aspidisca - replace stalked ones when SRT increases.
Sandip,
I dont think ciliates are the reason for the sludge to rise. If you are using diffused aeration system there are chances that air bubbles might get entrapped in the flocs making them lighter. If you are observing the rising after 2-3h of settling in a cylinder or in secondary clarifier, the reason could be denitrification. Let me know the exact reason so that I can clarify more.
- Badges
- Science topic