Gb. Ryhiner et al., MODELING AND SIMULATION OF ANAEROBIC WASTE-WATER TREATMENT AND ITS APPLICATION TO CONTROL DESIGN - CASE WHEY, Biotechnology progress, 9(3), 1993, pp. 332-343
Modeling and simulation of the anaerobic treatment of whey wastewater
was studied. A model including five groups of organisms, whey substrat
e, butyric, propionic, and acetic acids, CO2, H-2, and CH4, was develo
ped for single- and two-stage anaerobic fluidized bed reactors. It inc
luded thermodynamic limitations for the acetogenesis reaction, acid-ba
se equilibria of dissociating compounds (organic acids and CO2) for va
riable and constant pH situations, gas-liquid phase mass transfer, and
measurement dynamics. The model was adequate to describe both the ste
ady-state and dynamic behavior of the reactors and was used to study v
arious control schemes. In all cases the feed flow rate was the manipu
lated variable. Controls of pH, dissolved hydrogen, and organic acids
were all successful in simulation and experiment. Simulations were use
d to determine optimal control parameters for conventional proportiona
l-integral (PI) or proportional-integral-differential (PID) control. T
he experimentally found optimal values were in close agreement with pr
edetermined simulated values. Simple control using gas analysis result
s did not give stable control, either in the simulation or in the expe
riment.