Removal of a synthetic organic chemical by PAC-UF systems - I: Theory and modeling

Based on the age distributions of powdered activated carbon (PAC) in reacto rs, the competitive bi-solute isotherm and the pore-surface diffusion mecha nism, a model was developed to predict the removal of a trace synthetic org anic chemical (SOC) when PAC was applied to an ultrafiltration (UF) membran e system. Independent experiments evaluated the input parameters for the mo del. The pore diffusion in liquid-filled pore was the dominant internal mas s transfer mechanism in a PAC particle and the surface diffusion mechanism was neglected in the model. Model prediction was compared with data from pi lot plant experiments treating simazine in natural water. Due to the blendi ng and the increasing PAC in the UF loop, a transient behavior of effluent simazine concentration was observed in the UF effluent. The model predicted successfully this periodical Variation of the simazine concentration in th e UF loop effluent, as well as the simazine concentration in the effluent f rom the PAC slurry contactor. The faithful model prediction required the mo deling of the phenomenon of adsorption/desorption of an SOC on membrane its elf. (C) 2000 Elsevier Science Ltd. All rights reserved.