PAC-membrane filtration process. I: Model development

Adsorption is modeled when powdered activated carbon (PAC) is applied in co ntinuous-flow reactors followed by membrane filtration units operated witho ut carbon wastage between backwash events. Four reactor configurations are studied: (1) A membrane reactor dosed with a step input of PAC; (2) a conti nuous flow stirred tank reactor dosed with a step input of PAC and followed by a membrane reactor; (3) a plug-flow reactor dosed with a step input of PAC and followed by a membrane reactor; and (4) a membrane reactor dosed wi th a pulse input of PAC at the beginning of the filtration cycle. A steady- state operation is considered to describe the adsorption process through th e continuous-flow stirred tank reactor and plug-flow reactor, whereas adsor ption in the membrane reactor is modeled as a non-steady-state process. Ads orption kinetics is assumed to occur by homogeneous surface diffusion, and adsorption equilibrium is described with the Freundlich isotherm model. Ana lytical solutions of the homogeneous surface diffusion model with no extern al mass transfer limitation are used to evaluate adsorbate concentrations i n the solid phase as a function of time. Part II of this study presents mod el simulations and verification with experimental data obtained in a bench- scale apparatus.