CONTINUOUS CLASSIFICATION OF MOISTURE-CONTENT IN WASTE ACTIVATED SLUDGES

Bound water content is generally taken as an index for differentiating the moisture content in a sludge. However, some recent works have dem onstrated that such an index is an operationally defined value differi ng markedly when different techniques are employed. In this study, the continuous moisture distribution in waste activated sludge is constru cted on the basis of the combined thermal gravimetry analysis (TGA) an d differential thermal analysis (DTA). The water-solid bond strength i s considered here to be an adequate classification index. The bound wa ter contents measured via filtration, drying, or expression are interp reted as the portion of moisture displaying a bond strength higher tha n the threshold energy that could be provided by filtration, drying, o r expression tests. Employing one of these bound water measurement met hods is thereby equivalent to setting a threshold bond strength to div ide the continuous moisture distribution into bound water and free wat er. Moreover, the effects of a freeze/thaw treatment on the continuous moisture distribution are discussed.