Application of ADM1 to a UASB Treating Complex Wastewater in Different Feeding Regimes
Two upflow anaerobic sludge blanket (UASB) reactors treating dairy effluent were operated in a continuous mode and then were switched to an intermittent mode. In intermittent mode one reactor had 6 hours feeding followed by 6 hours non-feeding, while the other reactor had a period of 3 hours feed and a period of 9 hours without feed. During the experiment the reactors were subjected to different organic loadings, but the daily load was the same for both reactors for each organic load applied. Anaerobic Digestion Model 1 (ADM1) was used to model the reactors in both the continuous and intermittent feeding periods. Good correlation between the predicted and measured results was obtained in both phases. The biodegradable fraction of the feed substrate modelled by ADM1 was higher in the UASB with the longer period without feed and both biodegradable fractions were higher than those found for the continuous phase. Consequently higher gas production [corresponding to higher chemical oxygen demand (COD) removals] were observed for intermittent operation.