This invention relates to processes for producing acetic acid and, in particular, to improved processes for recovering permanganate reducing compounds formed during the carbonylation of methanol in the presence of a carbonylation catalyst to produce acetic acid. A predefined voltage is applied to the predetermined memory cell to generate an output current reflecting a resistance of the predetermined memory cell, and to one or more reference memory cells to generate a first reference current reflecting the high resistance state, and a second reference current reflecting the low resistance state. Responsive to such notice, the moving vehicle position is determined, and such position is used with the transmitter and receiver positions to determine whether the moving vehicle is located between the transmitter and receiver positions. The comparator outputs a comparison signal by comparing voltages of the test node and the reference node. The tilt rod is received in the recess when the louver is closed. An effluent from the first wastewater treatment zone is mixed with an effluent from the second wastewater treatment zone such that a predetermined ratio of carbon to nitrogen is maintained within the mixture of first and second effluents.