The ammonia in wastewater is to be converted to nitrate in a biore- actor. Initial concentration of ammonia is 145 mg/L. It is desired to achieve 90% conversion in a 50 m3 reactor. The design engineer is trying to select between a PFR and CSTR mode for operation of the reactor. Which mode of operation will allow the engineer to process a larger volume of wastewater within a shorter period of time?