A comparative study of freeze-thaw processes for conditioning wastewater and water treatment sludges

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6661623

Trahern, P G

This research effort involved the application of indirect- and direct-contact, freeze-thaw conditioning techniques for improving the dewatering characteristics of both waste water and water treatment sludges. Sludges tested included waste activated sludge, primary sewage sludge, waste activated/primary sewage sludge mixtures and alum sludge. The direct-freeze methods examined were the use of a secondary refrigerant (butane) evaporated in the sludge and the use of gas hydrate or clathrate formation by addition of Freon 12 under appropriate temperature and pressure conditions. Sludges were also frozen solid using indirect freezing methods, thawed and tested for comparative purposes. Particle size distribution and floc density measurements were used to determine changes in particle characteristics; specific resistance values and dewatered dry solids concentration were used to assess dewatering characteristics. Results of direct and indirect-contact, freeze-thaw conditioning were compared to the effects of polymer conditioning. The results indicated that direct-freeze methods do not appear technically or economically competitive with currently accepted conditioning methods. The superior results obtained with the indirect-contact, freeze-thaw process when compared to the direct-contact processes suggested that the extent and rate of freezing may greatly influence the particle characteristics of the conditioned sludge, and thus its dewatering characteristics.

• Research Organization: Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (USA)
• OSTI ID: 6661623
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320305* -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management
320604 -- Energy Conservation
Consumption
& Utilization-- Municipalities & Community Systems-- Municipal Waste Management-- (1980-)
ALKANES
BUTANE
CONCENTRATORS
DENSITY
DEWATERING EQUIPMENT
ECONOMICS
EVAPORATION
FREEZING
FREONS
GAS HYDRATES
HALOGENATED ALIPHATIC HYDROCARBONS
HYDRATES
HYDROCARBONS
HYDROGEN COMPOUNDS
LIQUID WASTES
MANAGEMENT
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXYGEN COMPOUNDS
PARTICLE SIZE
PERFORMANCE TESTING
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POLYMERS
PROCESSING
REMOVAL
SEWAGE
SEWAGE SLUDGE
SIZE
SLUDGES
TECHNOLOGY ASSESSMENT
TESTING
THAWING
WASTE MANAGEMENT
WASTE PROCESSING
WASTE WATER
WASTES
WATER
WATER REMOVAL
WATER TREATMENT PLANTS