There is an industrial wastewater treatment plant at which chemical treatment is being applied...
The flow - chart of the chemical treatment units of this plant is given below...
Wastewater flow - rate : 3,200 m3 / day Influent BOD5 : 500 mg / L Influent COD : 750 mg / L Influent SS : 150 mg / L
Assumptions...
Removal efficiency of SS : 70 % Dosage of Al2(SO4)3.18(H2O) : 5 mg / L Dosage of Ca(OH)2 : 3 mg / L SS Percentage of the chemical sludge : 1.50 %
Note : Type of the chemicals to be used and the optimum dosages of them must be determined by the "JAR Test"...
Calculation...
Correction Factors...
For Ca(OH)2 as Example...
Ca(OH)2
+
SO4- 2
Ca(SO4)
+
2 OH-
74 gr
96 gr
136 gr
74 gr
Ca(OH)2
136 gr
Ca(SO4)
1 gr
X
______________________________________
X = 1.84 gr / gr
Amount of SS Based Sludge After Chemical Treatment...
( 150 mg / L ) x ( 10- 6 kg / mg ) x ( 103 L / m3 ) x ( 3,200 m3 / day ) x ( 0.70 ) = 336 kg / day
Amount of Al2(SO4)3.18(H2O) Based Sludge After Chemical Treatment...
( 0.153 ) x ( 3,200 m3 / day ) x ( 5 x 10- 3 kg / m3 ) = 2.45 kg / day
Amount of Ca(OH)2 Based Sludge After Chemical Treatment...
( 1.84 ) x ( 3,200 m3 / day ) x ( 3 x 10- 3 kg / m3 ) = 17.67 kg / day
Amount of Total Sludge After Chemical Treatment...
MSLUDGE = 336 + 2.45 + 17.67 = 356.12 kg / day
Volume of the Total Sludge After Chemical Treatment...
VSLUDGE = ( 356.12 kg / day ) / [ ( 1,000 kg / m3 ) x ( 0.015 ) ] = 23.74 m3 / day
