to see if the ph cl tss and do levels of the fluent in the effluent reservoir 19 meet requirements for discharge for a preset time if so proceed to step 12 option 1 system shutdown is accomplished by the plc 50 performing the following steps 2 turn off current to the primary reactor 7 concentration reactor 10 and oxidation reactor 16 4 open the drain valves 8 11 17 24 25 option 2 system start up is accomplished by the plc 50 performing the following steps 4 close drain valves 8 11 17 24 25 7 check if the fluent in the primary reactor 7 and the concentration reactor 10 are at sufficient levels if so then proceed to step 8 8 turn on the current in the primary reactor 7 and the concentration reactor 10 to a preset value 9 check to see if the ph of the fluent entering the ratio weir 9 is within a preset range for a preset time if so proceed to step 10 11 check to see if the fluent in oxidation reactor 16 is at a sufficient level if so proceed to step 12 12 turn on current to oxidation reactor 16 to a preset value 13 check to see if the ph.