FREEZE-THAW TREATMENT ON ZONE SETTLING OF WASTE ACTIVATED SLUDGES

Zone settling characteristics of the original and frozen waste activat ed sludges had been investigated experimentally. Based on the Richards on-Zaki correlation, the apparent flee size and flee density for vario us sludge systems were estimated. Due to the global flee network exist ing in the original sludges, the apparent floc density for the settlin g sludge was much less than those of the constituting flocs, which was generally observed in the floc systems studied. After a freeze/thaw t reatment, nevertheless, the densities for the flocs were increased whi lst the apparent density of the sludge could be taken as an average ov er all the constituting flocs.