Accession Number : ADA205955


Title :   Development and Design of Sludge Freezing Beds


Corporate Author : COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH


Personal Author(s) : Martel, C J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a205955.pdf


Report Date : Dec 1988


Pagination or Media Count : 58


Abstract : 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.


Descriptors :   *SLUDGE , *FREEZING , *WASTE WATER , *THAWING , REMOVAL , LABORATORY TESTS , PARAMETERS , PHYSICAL PROPERTIES , INTENSITY , SOLIDS , DEPTH , WATER TREATMENT , DRAINAGE , ICE , OPERATION , WASTE TREATMENT , SEWAGE TREATMENT , MECHANICAL PROPERTIES , INPUT , SEASONS , THERMAL PROPERTIES , MATHEMATICAL MODELS


Subject Categories : Water Pollution and Control


Distribution Statement : APPROVED FOR PUBLIC RELEASE