Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
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1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
3. REPORT TYPE AND DATES COVERED
December 1996
4. TITLE AND SUBTITLE
5. FUNDING NUMBERS
A Device for Mechanical FreezeThaw Conditioning of Alum Sludge
PR: 4A762784AT42
WP: 211
WU: CO-M20
6. AUTHORS
C. James Martel, Rosa T. Affleck and Melinda L. Yushak
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
U.S. Army Cold Regions Research and Engineering Laboratory
72 Lyme Road
CRREL Report 96-15
Hanover, New Hampshire 03755-1290
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
Office of the Chief of Engineers
Washington, DC 20314
For conversion of SI units to non-SI units of measurement consult Standard Practice for Use of the
11. SUPPLEMENTARY NOTES
International System of Units (SI), ASTM Standard E380-93, published by the American Society for Testing and Materials,
1916 Race St., Philadelphia, Pa. 19103.
12a. DISTRIBUTION/AVAILABILITY STATEMENT
12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
Available from NTIS, Springfield, Virginia 22161.
13. ABSTRACT (Maximum 200 words)
This report contains the results of a study to develop a mechanical device for dewatering alum sludge by
freezethaw. This proposed device is a combination of two conventional unit operations: a vacuum filter and a
blast freezer. Bench-scale studies were conducted to evaluate this concept and develop preliminary design
criteria. The results of filter leaf tests indicate that a suitable sludge layer could be collected on a cloth medium
at a vacuum level of only 100 mm of Hg and a 5.0-minute filtration time. The volume of sludge was reduced by
67%. The freezing tests indicated that low freezing rate and a high initial solids content had a tendency to
produce large alum sludge particles. However, fast freezing rates could be achieved without reducing the
effective grain size below that of a fine sand. Curing time had no effect on grain size. The electrical cost of
freezing sludge with this device was estimated to be
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.004/m3, which is not expensive in relation to the totalcost of water treatment which is approximately
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.25 to
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.50/m3.14. SUBJECT TERMS
15. NUMBER OF PAGES
24
Alum
Water purification
Freezethaw conditioning
Water treatment plants
16. PRICE CODE
Sludge disposal
17. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
19. SECURITY CLASSIFICATION
20. LIMITATION OF ABSTRACT
OF REPORT
OF THIS PAGE
OF ABSTRACT
UNCLASSIFIED
UNCLASSIFIED
UNCLASSIFIED
UL
Standard Form 298 (Rev. 2-89)
NSN 7540-01-280-5500
Prescribed by ANSI Std. Z39-18
298-102
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