Abstract
In the activated sludge treatment commonly used in sewage treatment plants, the activated sludge in an aeration tank occasionally has a bulking phase, and the sewage water cannot be treated due to the difficulty of solid-liquid separation in a final settling tank. It is known that the excess activated sludge which is discharged from the general sewage treatment plant has very bad dewaterability. We have previously reported that the freezing and thawing treatment improved its solid liquid separation characteristics remarkably.
In this paper, we report the effect of the freezing and thawing treatment on the solid-liquid separation characteristics of bulking and normal sludges acclimated to glucose and peptone, and the comparison of this effect between normal and bulking acclimated sludges and sewage sludge. This freezing and thawing treatment improves the settleability of all the sludges, and the floc of treated sludge acquires a denser structure. The filterability of bulking acclimated sludge is worse than that of the other sludges. This treatment also, however, improves the filterability of all the sludges and has almost equal effects on all kinds of sludges.
