Development and design of sludge freezing beds
This study develops design criteria for a new sludge dewatering unit operation called a sludge freezing bed. This bed uses natural freeze-thaw to condition the sludge. The total depth of sludge that can be frozen, thawed and dewatered by this process in a year is the main criterion needed for design. Laboratory tests assessed the dewaterability of freeze-thaw conditioned water treatment plant sludge and both anaerobically and aerobically digested wastewater sludges at various depths. Mathematical models for predicting the design depth were developed; values for the input parameters to the models were obtained from the literature or from laboratory and pilot-scale experiments. The dewaterability tests indicated that the depth of sludge that can be applied is not limited by drainability. Up to 2.0 m of each sludge drained in minutes after freeze-thaw conditioning. Except for the aerobically digested sludge, the solids content after drainage is high enough to permit mechanical removal. The physical and thermal characteristics of frozen sludge were found to be equivalent to those of ice. An analysis of the freezing and thawing models reveals that the design of a freezing bed will depend on the duration and intensity of the freezing and thawing seasons.
- Research Organization:
- Cold Regions Research and Engineering Lab., Hanover, NH (USA)
- OSTI ID:
- 5860787
- Report Number(s):
- AD-A-205955/8/XAB; CRREL-88-20
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
320305 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management
320604* -- Energy Conservation
Consumption
& Utilization-- Municipalities & Community Systems-- Municipal Waste Management-- (1980-)
CONTROL
DEPTH
DIMENSIONS
DRAINAGE
FREEZING
HYDROGEN COMPOUNDS
ICE
LIQUID WASTES
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
OPERATION
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POLLUTION CONTROL
REMOVAL
SLUDGES
SOLIDS
THAWING
WASTE WATER
WASTES
WATER
WATER POLLUTION CONTROL
WATER REMOVAL
WATER TREATMENT