Activated Sludge Model

Calibration of hydrauhc model and aeration Cahbration of settiing model 4 i Simple steady state cahhration of activated sludge model ... 

Fig. 2. A systematic methodology for the calibration of activated sludge models...

A combination of the concepts behind Equations (2.28) and (2.29) is applied in the activated sludge model for the kinetics of the hydrolysis processes (Henze et al., 1987). This combined concept, originally proposed by Dold et al. (1980), includes a saturation type of expression and a heterotrophic biomass with a maximum capacity for hydrolysis ... 

Henze, M., C.P.L. Grady Jr., W. Gujer, G. v. R. Marais, and T. Matsuo (1987), Activated sludge model no. 1, Scientific and Technical Report No. 1, IAWPRC (International Association on Water Pollution Research and Control). 

Biomass and substrate must be separately described to establish a concept for classification of wastewater directed toward a description of the microbial processes. For several reasons, e.g., to allow widespread application and to observe a basic mass balance, the organic matter expressed in terms of COD is a central parameter for wastewater quality. According to the concepts used in the active sludge models, the classification of wastewater in a sewer network can also be subdivided as outlined in Figure 3.1 (Henze et al., 1987, 1995a, 2000). A direct interaction between sewer and treatment plant processes is therefore within reach. 

Henze, M., W. Gujer, T. Mino, and M. v. Loosdrecht (2000), Activated sludge models ASM1, ASM2, ASM2d and ASM3, Scientific and Technical Report No. 9, IWA (International Water Association), p. 121. 

Hydrolysis of particulate substrates produces readily biodegradable substrate for the biomass (cf. Figure 5.4 and Section 3.2.3). The kinetics of the hydrolysis, following the concept of the activated sludge model one, is described in Section 2.2.2. The following interpretation of hydrolysis of wastewater in a sewer is considered particulate substrate is available in the bulk water phase, and biomass in the bulk water and biofilm—assuming a reduced activity in the biofilm—is taken into account. Under these conditions, the rate of hydrolysis, rhydr, for each of the hydrolyzable fractions, n, is as follows ... 

In addition to the kinetics of the sewer processes described in Section 5.3, the stoichiometry of the transformations of the components is crucial for the mass balance. The stoichiometry of the biomass/substrate relationships is, according to the activated sludge model concept, determined by the heterotrophic biomass yield constant, YH, in units of gCOD gCOD-1. As depicted in Figure 5.5, the yield constant is an important factor related to the consumption of both Ss and S0 for the production of XBw. 

This set of coupled differential equations can—as also expressed for the activated sludge model concept—be formulated in terms of a matrix. This matrix includes the relationships between the relevant components, processes, expressions, process rates and coefficients (Table 5.3). The mass balances shown in Equations (5.6) to (5.9) can be identified as columns in the matrix. 

Kappeler, J. and W. Gujer (1992), Estimation of kinetic parameters of heterotrophic biomass under aerobic conditions and characterization of wastewater for activated sludge modelling, Water Sci. Tech., 25(6), 125-139. 

For biological treatment of composite effluent, the activated sludge model showed better results compared to those obtained by using a unit simulating a trickling filter. Activated sludge treatment yielded an effluent with an average BOD value of 40 mg 1 . ... 

The model used for the simulation is the Matlab implementation of BSMl [3], BSMl was developed for unbiased comparison of different control laws. The WWTP is modelled with five activated sludge tanks in series using the Activated Sludge Model 1 (ASMl) [5] and a secondary clarifier modelled according to the method of Takacs et al. [6] (see Fig. 1). All parameters are set as defined in the BSMl protocol. 

Models can be represented in the form of a process matrix the matrix shows all the components of the models, processes, rate kinetics, mass balances and stoichiometry. A thorough outhne on the use of process matrix is described in the activated sludge model [ 107]. All growth processes are based on Monod kinetics and switching functions to hterally turn on or off different biological processes. 

The processes affecting organic phosphorus concentrations that have been considered in widespread mechanistic models of aquatic systems are briefly described in the following subsections. To represent these processes, we use the process table formalism that has been popularized in wastewater engineering by the introduction of the activated sludge models (Henze et al., 1986, 1995,1999 Gujer et al., 1999). This process table formalism is shown in Table 16.1. 

Henze, M., Grady, C.P.L., Cujer, W., Marais, C.V.R. and Matsuo, T. (1 986) Activated Sludge Model No. I. Scientific and Technical Report No. 1, International Association for Water Pollution, Research and Control (lAWPRC), London. 

Manga, J., Ferrer, j., Carcia-Usach, F. and Seco, A. (2001) A modification to the Activated Sludge Model No. 2 based on the competition between... 

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