A fermentor is used to measure the dissolved oxygen concentration. The DO was measured by initially sparging the reactor with nitrogen to remove dissolved oxygen, then aerating the fermenter. The data is provided in the table below. The saturated DO concentration is 7.35 mg/L. Determine kla. Time (min) DO (mg/L) 0 0.5 5 10 18 15 2.5 3.6 4.4 20 5.0 25 5.5 30 3 37 6 6.3 (12)