(483c) Accurately Modeling Liquid Phase Adsorption for Industrial Applications with Bench Scale Testing

Granular activated carbon (GAC) has been proven to remove contaminants in vapor and liquid phase applications for decades. Vapor phase adsorption data has been well documented in literature and modeling exists for the design of vapor phase applications. Liquid phase applications, however, are more difficult to model due to the complex interactions present in liquid chemistry. The contaminants of interest are in a matrix of organic and inorganic compounds that interfere with adsorption. Therefore, laboratory testing is suggested to determine the effectiveness of carbon for specific applications, the size necessary for an industrial scale treatment system, and the carbon usage rates in full-scale systems to optimize removal and cost.

Lab scale testing can be divided into two categories; feasibility and process simulation. Feasibility testing is typically accomplished with an isotherm test. An isotherm is a batch test designed to demonstrate the degree to which a particular dissolved organic compound (adsorbate) is adsorbed on activated carbon (adsorbent). For a single adsorbate, a Freundlich equation can be used to estimate the carbon usage rate at equilibrium loading conditions. Continuous flow tests such as small-scale column tests and pilot studies simulate not just the thermodynamic adsorptive properties demonstrated in the isotherm, but they also allow for an accurate representation of the kinetic factors which effect adsorption in a dynamic system. The adsorption breakthrough curve obtained is scaled to accurately represent treating an aqueous stream in a large adsorption system.

The results from this testing provide sufficient data to determine the most economical approach for installing and operating GAC for a wide range of liquid phase applications.