Full-scale application of a dynamic model for high-rate anaerobic wastewater treatment systems

High-rate anaerobic treatment systems are becoming increasingly popular to treat industrial wastewater containing large amounts of organic matter in the form of carbohydrates or proteins. Mathematical models of these systems can serve as tools for equipment sizing, process design, control and optimization, plant operation, and operator training. Several models for these plants have been proposed which have been validated and tested on laboratory-scale systems. Information on full-scale application of these models is not readily available. In this paper, a model only previously validated on laboratory scale was applied at full scale. The model was used to predict the behavior of two full-scale plants of different designs treating brewery wastewater under dynamic conditions. Influent and effluent liquid streams and gas flows were sampled over a 4 and 10 day period for the two plants, respectively. Limited characterization to just total carbon in feed over only four days was sufficient to predict the gas production rate or total volatile organic acid concentration in the effluent of the methanogenic reactor. Elaborate measurements over 10 days of feed characteristics including organic acid concentrations were important in obtaining good full-scale predictions of all variables that were modeled. Apart from the operating variables, the key parameter that required re-estimation for the full-scale system was the solids retention time in the methanogenic stage.