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Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water
Patterson, C., H. Salih, D. Betts, AND C. Impellitteri. Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water. Presented at EWRI World Environmental and Water Resources Congress 2015, Austin, TX, May 17 - 21, 2015.
This project investigated the feasibility of regenerating an AC slurry by photo-degradation in situ through bed expansion and exposure to light. Safe and energy efficient removal of organic contaminants from our nation’s drinking water will reduce the carbon footprint of our treatment technologies. Efficient removal of harmful organic chemicals will also ensure safe and clean drinking water and will promote and maintain environmentally sustainable communities.
The regeneration and reuse of exhausted granular activated carbon (GAC) is an appropriate method for lowering operational and environmental costs. Advanced oxidation is a promising environmental friendly technique for GAC regeneration. The main objective of this research was to determine whether it is physically possible to get enough light into a slurry of GAC to initiate photo-catalytic reactions for regeneration of exhausted GAC. Two different scalable experimental setups were adopted for the light intensity studies. Namely, a traditional filter backwash technique and a falling film reactor. An Opto-meter equipped with a visible light detector was used to measure the light intensity of the different bench scale experiments. Three experimental conditions were investigated in various combinations, specifically 1) four GAC particle sizes, 2) slurry mixing conditions and speed, and 3) GAC slurry density i.e. GAC w% to DI water w%. Isotherms and column breakthrough studies were also conducted on phenol adsorption in GAC and GAC impregnated with titanium dioxide nanoparticles (TiO2 NPs). The adsorption behavior of the virgin TiO2 NP loaded GAC was compared to the un-impregnated GAC and the regenerated impregnated GAC. Visible light activated TiO2 NPs were synthesized in house at particle size distribution ≥10 nm. Two types of chemically activated GAC with different pore size distribution were prepared and Calgon Carbon Filtrasorb 400 were used for the adsorption studies. The light transmission through the GAC slurry in the traditional filter backwash technique was a function of the GAC particle size, the mixing speed and the bed volume expansion. The light transmission through the GAC slurry in the falling film reactor was a function of the particle size and the surface coverage. The loading rate of the TiO2 NPs on the GAC was dependent on the surface area, the pore size distribution of the GAC, and the particle size distribution of the NP. This presentation will summarize the findings of this study in more detail.
Record Details:Record Type: DOCUMENT (PRESENTATION/SLIDE)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
WATER SUPPLY AND WATER RESOURCES DIVISION
WATER QUALITY MANAGEMENT BRANCH