Page 230 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Flotation 185

8.10 Mass Balance and Released Air Required (1) Independent variables (input to Table CD8.3)
Reference is Section 8.3.5 and Table CD8.3.
Given Magnitude of Variable
Variable Units
T (8C) 20 2 30
T ¼ 208C N p ¼ 12,000 #=mL Z (elevation) (m) 0 0 0
d b ¼ 40 mm B ¼ 10 bubbles=particle D(nozzles) (m) 3.0 3.0 3.0
(mm) 40 40 40
d b
(mm) 50 50 50
d p
Required N p (#=mL) 12,000 12,000 12,000
Calculate C r , the ‘‘air released’’ or excess air required to B (bubbles=particle) 10 10 10
float the floc particles. r (dimensionless) 0.10 0.10 0.10
8.11 Mass Balance and Maximum Air Concentration at
Note that the independent variables other than temperature are the
Nozzles
same.
Reference is Section 8.3.5 and Table CD8.3.
Given
Required
Examine the effect of temperature on N b , C r , C a , C o ,
T ¼ 208C P(saturator).
D(nozzles) ¼ 40 mm 8.14 Mass Balance and Role of Elevation
The effect of elevation above sea level on P(saturator)
and other dependent variables is explored through appli-
Required
cation of the spreadsheet, Table CD8.3. Reference is
Calculate C a , the maximum ‘‘air’’ concentration at noz-
Section 8.3.5.
zle level and which leaves the flotation basin in the
Given
flows, Q and R, respectively (assuming no losses in
The input variables for Table CD8.3 are shown with
dissolved gases due to interface mass-transfer
variation in Z.
exchanges).
8.12 Mass Balance and Recycle Ratio
(1) Independent variables (input to Table CD8.3)
Reference is Section 8.3.5 and Table CD8.3.
Given
Magnitude of Variable
The input variables for Table CD8.3 are Variable Units
T (8C) 20 20 20
Z (elevation) (m) 0 1,586 3,000
T ¼ 208C N p ¼ 12,000 #=mL f ¼ 0.90
D(nozzles) (m) 3.0 3.0 3.0
d b ¼ 40 mm B ¼ 10 bubbles=particle
d b (mm) 40 40 40
D(nozzles) ¼ 40 mm r ¼ 0.10
d p (mm) 50 50 50
(#=mL) 12,000 12,000 12,000
N p
B (bubbles=particle) 10 10 10
Calculation results from Table CD8.3 that go into the
r (dimensionless) 0.10 0.10 0.10
mass balance relation are
Note that the independent variables other than elevation, Z, are the
same.
3
C r ¼ 0.0048 kg air=m water
3
C a ¼ 0.024 kg air=m water
3
C o ¼ 0.0311 kg air=m water Required
Examine the effect of elevation on N b , C r , C a , C o ,
P(saturator).
Required 8.15 Sizing Plan Area of Basin by Empirical Criteria
Calculate P(saturator) from Table CD8.3. Reference is Section 8.4.1 and Table 8.4.
8.13 Mass Balance and Role of Temperature Given
3
The effect of temperature on P(saturator) and other Q ¼ 0.044 m =s (1.0 mgd)
dependent variables is explored through application of r ¼ 0.10
the spreadsheet, Table CD8.3. 2.5 SOR 26 m=h (Table 8.4)
Given Required
The input variables for Table CD8.3 are A(flotation basin)