7. Water arriving at the disinfection step in a 4 MLD (million liters per day) wastewater treatment plant contains 50,000 CFU/100 mL (CFU = colony forming units) of the pathogen E. coli. After chlorine is added, the E. coli concentration decreases with first-order reaction kinetics, with a reaction rate constant of 0.15 h.!. Chlorination occurs in a 600,000-liter tank with baffles that make the water approximate plug flow. At the end of the tank, sulfur dioxide is added to achieve dechloriationit reacts with and eliminates chlorine, halting disinfection. At this point, what is the E. coli loading in CFU/100 mL