Abstract
Experimental investigations of the effects of the different kinds of hydrogen donors addition on the sludge selfimmobilization of upflow sludge blanket (USB) denitrification reactors were carried out. Results indicated that highly settleable and active granular sludge was produced when using methanol as the hydrogen donor andHyphomicrobiumwas the dominant bacteria in the granular sludge. On the other hand, in tests using glucose and acetate as the hydrogen donor, reactor performance was much poorer than when using methanol as the donor. Although the mechanism of sludge self-immobilization could not be made clear, the factors such as tangling of filamentous-like bacteria, gentle mixing, upflow reactor situation and extracellular biopolymers production, seem to be most important for granular sludge formation in comparison with other self-immobilization processes.
