AUTOMATIC-CONTROL OF EFFLUENT QUALITY FROM A HIGH-RATE ANAEROBIC TREATMENT SYSTEM

An anaerobic fluidized bed reactor was overloaded with up to 42 g molasses 1- day-. The effluent quality, expressed in total acids concentration, was successfully regulated by an automatic control algorithm, with alkaline consumption as the controlled variable and feed rate as the manipulated variable. The effluent quality could be maintained at any required level, from 100 to 400 mg acids 1-, depending on the setting of the control parameters. Moreover, it is possible to keep the acid addition within a certain range, setting higher and lower thresholds in the controller. This option requires the use of equalization capacity and is particularly suitable for handling surges of higher than average concentration waste. At lower waste concentrations, the feedrate is automatically increased, allowing the reactor to run at maximum loading with the effluent still satisfying quality requirements. © 1990.