2. Sludge Dewatering by Freezing(Papers presented at the 36th Annual Meeting, April, 1990, Tokyo)

Abstract

Dewatering of waste activated sludge by freezing was investigated in this paper. Freezing temperature of the waste activated sludge ranged ordinarily from -10℃ to -20℃, but freezing velocity depended on the freezing equipment. Frozen sludge was thawed and then dewaterd by the vacuum filter. Freezing improved the sludge dewaterability. Moreover, ice nucleating active bacteria was used to accelerate the freezing for shortening the freezing time. Addition of ice nucleating bacteria at the final concentration of 0.06 g/l decreased the freezing time remarkably. It suggested to be able to save the freezing energy in this process.