A pilot study was conducted to strip TCE at a concentration of 230 ppb from a contaminated groundwater using a small packed tower air stripper containing 50-mm diameter polytethylene intalox saddles. The packed tower was 30 cm in diameter with sampling ports located at packing depths of 0,2,4,6,8,10, and 12 meters. The loading of water to the tower was 0.039 m^3/(m^2/s), and the temperature of groundwater was 10 degrees celcius. The table below shows measure TCE concentrations in the water for several of the sampling ports:
Depth (m) TCE conc. (ppb) NTU
0 230
2 100
4 55
6 25
8 16
a) Determine the NTU values for each sampling port depth.
b) What was the overall mass transfer coefficient (Kla,s^-1) for TCE under the conditions studied in the pilot-scale test?
c) From the pilot-scale study, what packing depth in the tower would have been needed to obtain a concentration of 5 ppb TCE in the groundwater?