An ozone, O3, sparger system has been proposed for a water-treatment plant. The incoming water in a 80 m3 pond has been stripped of all ozone-demanding substances, and the pH is sufficiently low such that the ozone decomposition will be insignificant. The ozone bubbler will have eight spargers, each using a compressed gas feed containing 4 mol % ozone. The spargers will be located 3.2 m below the surface of the pond and each sparger's gas rate will be 17.8 m3 /h. Henry's law constant for the ozone-water system will be 0.0677 atm/(mol/m3 )
a. Use the Eckenfelder plot for oxygen transfer factor, kL(A/V), and evaluate the kL(A/V) for ozone, recalling that the penetration theory predicts, for mass transfer from gas bubbles into liquids, that kL(A/V) will be proportional to the liquid diffusivity raised to the power of 1/2. The diffusivity of oxygen in water is 2:14 × 10-5 cm2/s and the diffusivity of ozone into water is 1:7 × 10-5 cm2/s.
b. Determine the time required to raise the initially ozone-free water in the pond to a concentration level of 0.15 mol/m3.