Studies on the State of Water in Sludges with High Resolution NMR

Abstract

The state of water in sludges has been studied in terms of NMR spectra. The samples used were aluminum hydroxide and an activated sludge. The latter was obtained from a standard artificial sewage. Water content of the samples was changed by evaporation at a room tern-perature and NMR spectra of the samples were measured with 100 MHz High Resolution NMR.The amounts of bound water in aluminum hydroxide and in an activated sludge were estimated to be 1.4 and 3.0 g/g of dry solid, respectively, on the basis of the relationship between water content and line width (Fig. 4). After the samples had been freezed and thawed, the mobility of water in aluminum hydroxide increased, whereas that in an activated sludge almost un-changed (Fig. 6 and Fig. 7). When the samples were heated, the mobility of water in both samples increased with rising temperature (Fig. 9). After the samples had been heated at 90°c for 0.5 h and cooled to 33°c, the mobility of water in an activated sludge almost returned to its original value. whereas that in aluminum hydroxide did not.