Page 885 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

840 Appendix F: Alum Data and Conversions

TABLE F.2
Data for Liquid Alum (Dissolved Aluminum Sulfate) a,b
Property Notes Data
Formula 14 waters of hydration Al 2 (SO 4 ) 3 14H 2 O
Common name Name for Al 2 (SO 4 ) 3 14H 2 O Liquid alum
Molecular weight Approximate-for commercial 594
Specific gravity g solution=g water at 608F 1.335( 0.002)
Baumé, 608F Hydrometer reading 36.4
Also: quick measure of strength through use
of manufacturer’s tables (see also AWWA
Standard B403-98 and Spreadsheet CDF.3
for quick conversions)
Density g solution=L solution 1.330–1.342 c
lb solution=gal solution 11.1–11.2
Concentration (SG ¼ 1.335) g Al 2 (SO 4 ) 3 14H 2 O=L solution 647 c
lb Al 2 (SO 4 ) 3 14H 2 O=gal solution 5.4
Percent by mass 8.1–8.4
Al 2 O 3
Solubility g Al 2 (SO 4 ) 3 14H 2 O=L solution 1,050 d
Shipping—tank truck m 3 E-12.5-20.8 c
gal 3,300–5,500 e
Shipping—rail car m 3 E-30.3–68.1 c
gal 8,000–18,000
Storage tanks Capacity-minimum 28.4–56.8 c
7,500–15,000
Material (indicative list) Fiberglass=epoxy
Polyester
Appurtances Liquid level Manometer
Flush connections Piping=pumps=metering
pH pH versus % Al 2 (SO 4 ) 3 14H 2 O Mass% pH f
(pH is given as a property) 1 3.5
50 2.4
Temp. (8F) (%dry alum)
Freezing temperatures Percent Al 2 (SO 4 ) 3 14H 2 O with corresponding 32 0
temperatures at which freezing will occur 30 10
25 25
20 33
14 40
4 48
a
General Chemical (1995).
b
General Chemical Product Data Sheet, General Chemical Corporation, Parsippany, NY, (1997b).
c
Calculated from data in line below as given by General Chemical in U.S. Customary units.
d
Harringer (1984) states solubility is 105 parts in 100 parts water.
e
Tank truck maximum weight is 80,000 lb. Weight of truck plus fuel 32,000 lb, permitting a cargo weight 48,000 lb
(Jones, 1994). Therefore, the calculated cargo weight=g(alum) ¼ 48,000 lb=11.1 lb=gal ¼ 4,324 gal.
f
pH is of interest relative to dilutions that may be on interest in pilot plant work. The idea is to maintain the pH at levels
such that the predominant species is Al 3þ and hydrolysis products do not form. Generally pH 4.0 is safe for this
purpose.

F.4.5.1 Equivalent Concentration Expressions solution, 373 g Al 2 (SO 4 ) 3 =L solution, 111 g Al 2 O 3 =L solu-
tion, and 58.5 g Al 2 =L solution. The conversions are based on
Equivalent alum concentrations for the five expressions are
shown in Figure F.4a for SG(alum solution) ¼ 1.335 with molecular weight ratios, i.e., 666.132=594.136, 342.15=
corresponding concentration of 647 g Al 2 (SO 4 ) 3 14H 2 O=L 594.136, 101.961=594.136, 53.964=594.136, respectively.
solution. Using the latter as a basis, equivalent alum concen- Figure F.4a is useful for quick reference if conversions are
trations, seen in Figure F.4a, are 725 g Al 2 (SO 4 ) 3 18H 2 O=L needed.