Q9.7 a water analysis yielded the following results. CO= 8.8 mg/L Ca2+ = 70 mg/L
ID: 524699 • Letter: Q
Question
Q9.7
a water analysis yielded the following results.
CO= 8.8 mg/L
Ca2+ = 70 mg/L
Mg2+ =9.7 mg/L
Na2+= 6.9 mg/L
HCO3- = 115 mg/L as CaCO3
SO4 2- = 96 mg/L
Cl- = 10.6mg/L
(a). draw a bar graph miliequivalents per litre(meq/L) for determining lime and soda ash requirements to soften the water to the practical limits of hardness removal (40mg/L as CaCO3 and 10 mg/L magnesium hardness as CaCO3)
(b). calculate the quantity of lime in prounds per day as calcium (Cao) with a 98% purity needed to treat 5.0 MGD of flow using axcess lime treatment ( 1.25 meq/L)
(c). calculate the quantity of soda ash (Na2CO3) in pounds per day with a 95% purity needed to treat 5.0 MGD of flow.
Q9.10
two long rectangular settling basins operate in parallel to trat 5 MGD of coagulated water. A length to width (L:W) ratio of 4.1 and length to depth (L:D) ratio of 10:1 will be used in design over flow rate = 1000 gpd/ft^2
(a). determine the dimensions settling basin in feet assuming a depth of 10feet
(b). calculate the detention time if each basin in hours
(c). determine the length of effluent weir in each basin if the weir loading rate is not to exceed 12000 gpd/ft.
Explanation / Answer
Q9.10
two long rectangular settling basins operate in parallel to trat 5 MGD of coagulated water. A length to width (L:W) ratio of 4.1 and length to depth (L:D) ratio of 10:1 will be used in design over flow rate = 1000 gpd/ft^2
(a). determine the dimensions settling basin in feet assuming a depth of 10feet
(b). calculate the detention time if each basin in hours
(c). determine the length of effluent weir in each basin if the weir loading rate is not to exceed 12000 gpd/ft.
Determine the surface area of the settling basins using Equation
V = Q/As
As = Q/Vo
As = Q/Vo = 2.5 x10^6/ 1000 gpd ft^ 2 = 2500ft ^2
A = L×W = 2500ft Since
L = 4W, then 2 S A = 4W×W = 2500ft
W = 25 ft and L = 4×25 = 100 ft
Since L:D = 10:1, then D = L/10 = 100 ft/10 = 10 ft
Determine the detention time of the settling basins using Equation
Theta = V/Q= 100ft * 25ft *10ft /2.5 *10^6 gal [7.48gal /ft^3][24 h/d] =1.8 h
calculate the weir length as follows by rearranging Equation
Weir Length =Q /Weir Length
Weir Length =Q / Weir Loading Rate=2.5 *10^6gpd /12,000 gpd /f =208ft/basin
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.