Activated sludge process kinetics

Process-Specific Kinetics of the Conventional Activated Sludge Process Systems with Sludge Recycle... 

Specific Kinetics of the Improved Activated Sludge Process Using Secondary Flotation... 

The reaction and separation synthesis approach of Section 5 has been adopted to the problem of activated sludge process design (83). The conventional designs as well as all novel schemes for combined oxidation/denitrification of wastewater are explored. The process is optimized using a novel methodology for optimal reaction/separation network synthesis, supplied with a comprehensive kinetic model (84). The activated sludge process is synthesized using the systematic... 

For example, the material balance for the microbial kinetics of the activated sludge process is often written as (Metcalf and Eddy, Inc., 1991) ... 

Equation 75, however, is incorrect. Note that there is a flow Q into and out of the reactor. This means that the system is open and the full derivative, dXIdt, cannot be used. Nothing in the literature points out this mistake, however, because everything is written the same way. The Reynolds transport theorem distinguishes the difference between the total and partial derivatives, so wrong equations like the previous one will not result in any derivation if using this theorem. After the derivation below of the theorem is complete, we will come back and derive the correct material balance of the microbial kinetics of the activated sludge process. 

Munz et al. (2009) evaluated the role of tannins in both conventional activated sludge processes (ASP) and MBR. They found similar values in the removal of natural and synthetic tannins by comparing the two treatments. Further, in both processes the nitrification process presented extremely reduced kinetics. Finally, the inhibition of the nitrifying biomass was attributed to the whole wastewater rather than the non-biodegradable fraction. 

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 ... 

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. 

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. 

When one considers the relative simplicity of the design analysis above with the complicated nature of the physical and biological processes involved in the operation of an activated sludge facility, it is remarkable that equations (13.3.1) to (13.3.14) provide a reasonable description of the steady-state behavior of the concentrations of the limiting substrate and the lumped microorganisms when one has access to the corresponding kinetic parameters (iVax> and Fx/s) obtained using... 

Activated sludge wastewater treatment is the most common example of an aerobic suspended culture process. Many factors must be considered in Ac design and operation of an activated sludge wastewater treatment system. These include parameters involved with the process modeling and kinetics. The microbiology of the system must be considered. In addition to BOD removal, phosphorus and nitrogen removal must also be taken into account. Oxygen transfer and solids separation are important. Industrial wastes and the fates and effects of industrial chemicals (xenobiotics) must also be considered. 

Contents Indude process theory, treatment of municipal wastewater, and treatment of industrial wastes. Industrial waste treatment topics include pretreatment, oxidation of sludges, kinetics, effluent variability, inhibition, volatile stripping, nitrification/denilrifica-tion. powdered activated carbon, and priority pollutant removal. 

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