Question

2.(40 pts) You are to design an activated carbon adsorption system for treatment of drinking water containing Chlordane, a termite pesticide that contaminates Honolulu soils and leaches into the drinking water. The Freundlich isotherm constants (Table 13.2) and K = 190 (mg/g)(L/mg)', and 1/n = 0.33. The water to be treated has a chlordane concentration of 0.1 mg/L. Since the MCL is 0.002, you must design for an equilibrium concentration of 0.0005 mg/L. The flow rate is 1 MGD. Assume a carbon density of 30 lb/ft, and a typical carbon column depth of 10 ft. The carbon contractors must provide one year of treatment before new carbon is needed. Specify the following: a) total carbon mass(lb) b) the number of columns and their diameter (ft) c) the contact time in each column (min) Note: 1 MGD = 694 GPM = 1.547 ftels.

Answer 1

strona k cei m NE K ce Freundlich Isotherm Emperical Derivation is Yn m mg adsorbate 19 activated carbon ; Freundlich Capocity factor'; (mal 9 )(hong) adsorbate in : Equilibrium concentration of solution after adsorption in magle Monsin) Yon : Freundlich intensity parameters 190 (mg/g) I Inha 1/ing)" ce=0.0005 mg ♡ =0.33 :: o z 190 (0.0005) = 15-46 Total amount of chlorine concentration removed = 0.1-0.0005 =0.0995 mahe Given k= 2 0:33 m MLPD Flow rate = 3.785 IMGD = 1362'6x106 el year Given carbon contactors must provide one year of treatment before new carbon is esoteed : Amount adsorbate removed in one year of =1362.6 x 106 Litres *0.0995 mg/l = 135,578,700 adsorbate in be of mg CS Scanned with CamScanner

removed of 2 n broma m = 8769.6 kg entus and of Ag of =!37,578,700) 110) / 3.048) Amount Carbon suquired 즘 15.4 6 15.46 15.46 pride :: Amount a Carbon required - 8769:6) = 19, 333.64 lbs Area section, Activated Generally, the cross Carbon contactors is taken Take com² Total volume of contractor required M 8769.6 kg +1806 m3 48.55 kg/m3 [::p 3066143 - 48.55 kg/m3) Given typical Carbon Column depth 53.048 m Volume -30.48 m3 Contractors required = 180'6 = 5-92 ~6 in range, 5-30m2 ra lott ND of 30-48 CS Scanned with CamScanner

are provided .; 6 columns of contractors Diameter of contactor, d = 1014 tal= 357M of ple =171 H 2Ft » Anmeter column = 12 54 Genually, the contact time Adsorption is token in range of 2-10 min 5 minutes. het take Carbon of contact time CS Scanned with CamScanner