Activated Sludge and Other Aerobic Suspended Culture Processes

Abstract

PROCESS MODELING AND KINETICSModels. Full-scale modeling was conducted at the Tougas wastewater treatment plant (WWTP) in Nantes, France (Printemps et al., 2004). Despite the simplicity of the model used, good agreement was obtained between the model and the nitrogen balance within the plant. Daily sludge production was also modeled adequately. Ekama and Wentzel (2004) developed and validated a simple model for predicting the inorganic suspended solids concentrations in ordinary and biological nutrient removal activated sludge systems. Model predictions were heavily influenced by the degree of enhanced biological phosphorus removal (EBPR) occurring. Transient phenomena during batch tests for parameter determination for the calibration of activated sludge models (ASM) were observed . Errors in yield, maximum specific growth rate, and half saturation coefficient averaged 3,12, and 17% respectively. These transient phenomena were hypothesized to be the result of a sequence of 1158 intracellular reactions induced by the transient change in substrate concentration occurring in the batch tests.A suspended solids mass balance model was developed and calibrated using the operating data from a full-scale recirculating activated sludge plant . The model predicted a maximum of 25% reduction in solids loading to the secondary clarifiers when aeration tank settling was employed during rainfall events. Oliveira-Esquerre, evaluated steady state and dynamic models for predicting performance of a pulp and paper mill aerated lagoon effluent. Multiple linear and partial least squares regressions were compared in the developed neural network model. With limited sampling data the multilayer perception neural network model was more accurate at predicting effluent concentrations than the functional-link neural network model . Recurrent neural network and modified genetic algorithm models were used to optimize a fed-batch reactor (Chen, Nguang et al., 2004). The simulation provided accuracy within 8% of measured values. Guisasola et al. (2004) modeled the behavior of the polyphosphate accumulating organisms (PAO) under anaerobic/aerobic conditions and under just aerobic conditions by using the ASM2 and AnOx models with two hypotheses (PAO-hypothesis and ordinary heterotrophic organism (OHO)-hypothesis). They observed that since the storage of the phosphate in the aerobic phase was related with the ordinary heterotrophic organisms, OHO hypothesis results characterized the experimental data more accurately than the PAO hypothesis. 1159 Saikaly and Oerther (2004) examined the competition of six bacterial species in lab-scale activated sludge systems containing three limiting nutrients (resources) operated at solids retention times of 2.3 to 5.7 d. Their investigation demonstrated that the natural oscillations of bacterial communities ensure that the degree of diversity of a system (as measured by the number of coexisting bacterial species) will be larger than the number of limiting resources. Zinn et al. (2004) investigated growth models...