Activated Carbon Treatment Process Research Articles

Combined Treatments Consisting of Calcium Hydroxide and Activate Carbon for Purification of Xylo-Oligosaccharides of Pre-Hydrolysis Liquor.

In this study, the effect of a combined treatment consisting of calcium hydroxide (CH) followed by activated carbon (AC) on the purification of hemicellulose in the pre-hydrolysis liquor (PHL) from pulping process has been evaluated. The results show that lignin and furfural of PHL are efficiently removed, and the lignin removal is achieved by forming complexes onto CH particles in the CH treatment process, while acetic acid (acetate) is formed from the hydrolysis of acetyl groups present in the dissolved hemicelluloses in the PHL. The loss of xylo-oligosaccharides (XOS) is moderate, even at a high CH dosage of 0.8% while the xylose concentration is essentially unchanged. For the AC treatment, the optimal treating pH can enhance the interactions between AC and residual lignin and change the zeta potential of AC resulting in improved lignin adsorption onto AC. An increase of AC dosage has the tendency to adsorb more XOSDP>6 than XOSDP2~6. Overall, 66.9% of lignin and 70.1% of furfural removals are achieved under the optimal conditions of CH and AC treatment process, with a 5.9% total xylosugars loss. The present combination of CH and AC treatment process was more effective and selective for purification of xylosugars of PHL.

Cost effective activated carbon treatment process for removing free chlorine from water

AbstractExperiments of batch treatment and column breakthrough were conducted to compare the dechlorination effectiveness of five activated carbons: three made from coal (of different activation) and one each from coconut shell and fruit nut/shell. The removal of free chlorine was accomplished by physical adsorption and chemical reaction; adsorption was the main removal mechanism initially while chemical reaction by catalytic reduction was responsible for continued removal of free chlorine. Removal of free chlorine was enhanced by a longer contact time, a lower pH, and a higher initial/influent free chlorine concentration. Using < 180 mesh particles of activated carbon in mixed batch reactors, the carbon's adsorptive capacity for free chlorine was established in 2 h; the carbons' adsorptive capacities for free chlorine were in the same order as their phenol numbers, the indicator of small micropores. The coconut carbon had the highest adsorptive capacity but was much less reactive relative to the commercial coal and fruit shell carbons. Much more free chlorine was removed in the lab carbon columns than the carbons' adsorptive capacities due to catalytic reduction of the adsorbed free chlorine on carbon surface. The free chlorine removal capacities of the two spent carbons were similar to the respective new carbons. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

To Discussion of: Estimation of the removal of organic priority pollutants by the powdered activated carbon treatment process, G. O'Brien, 64, 877 (1992); Discussion by J.-F. Kuo, T. Hashman, 66, 89 (1994).

To Discussion of: <b>Estimation of the removal of organic priority pollutants by the powdered activated carbon treatment process,</b> G. O'Brien, <b>64,</b> 877 (1992); Discussion by J.-F. Kuo, T. Hashman, <b>66,</b> 89 (1994).

A systematic scanning electron microscopy technique for evaluating combined biological/granular activated carbon treatment processes

Abstract A systematic scanning electron microscope analytical technique has been developed to examine granular activated carbon used as a medium for biomass attachment in liquid waste treatment. The procedure allows for the objective monitoring, comparing, and trouble shooting of combined processes by direct visual examination of the biomass's attachment characteristics and rating key criteria that have been found to have the greatest effect on the process's performance. These criteria include the surface characteristics of the carbon; the quantity, type, and position of the biomass; and the amount of unidentifiable material. A set of instructions along with a set of reference photographs that illustrate the rating scale of each criteria were developed as was a standard data recording form. Several investigators rated samples from a variety of bioreactors to verify the practicality and quality of the technique. A comparison of the individual ratings indicated a significant correlation with each other as well as with the reactor's operating status.

Estimation of the removal of organic priority pollutants by the powdered activated carbon treatment process

ABSTRACT: Federal guidelines have been issued that regulate the aqueous discharge concentrations of priority pollutants for the organic chemicals, plastics, and synthetic fibers industries. Insufficient data existed in the literature to allow estimations of the removal of priority pollutants by a wastewater treatment plant (WWTP). The removals of 18 problem organic priority pollutants were measured in five parallel, aerated, continuous, mixed reactors. The influent to the laboratory pilot plants was primary effluent from an industrial 1.75 m3/s (40 Mg/d) WWTP at Du Pont's Chambers Works in Deepwater, N. J. This plant utilizes powdered activated carbon in combination with activated sludge (PACT® Process) in the aeration tanks. The kinetic coefficients that characterize removal by biodegradation, powdered activated carbon adsorption, and air‐stripping were obtained from the pilot‐plant data, and a steady‐state model was used to predict priority pollutant removals. Good agreement was obtained,”with the exception of three compounds that were batch discharged from the process sources, which invalidated the steady‐state assumption. The model was used to design a second stage PACT unit and to determine source control requirements. The model also can be used to estimate the relative importance of the three removal mechanisms in order to adjust WWTP operating conditions to enhance the removal of specific compounds.