Regeneration of granular activated carbon using hydrothermal technology

Technical Report · Sat May 01 00:00:00 EDT 1999

OSTI ID:6342509

Sufnarski, M D

The economic feasibility of using granular activated carbon (GAC) to remove organic contaminants from industrial and municipal wastewater is contingent upon its reuse during multiple adsorption-regeneration cycles. The most common process for the regeneration of GAC is the thermal method. Drawbacks associated with thermal regeneration include a 5--10% loss of carbon due to oxidation and attrition, a decrease in adsorption capacity, and high energy costs. The purpose of this study was to investigate the regeneration of GAC using hydrothermal technology. Phenol contaminated and non-contaminated GAC samples were regenerated using supercritical water (411 deg C and 26.2 MPa) with dissolved oxygen concentrations of 0 mg/L, 5 mg/L, and 100 mg/L. For comparative purposes, GAC was regenerated using subcritical water (300 deg C and 12.4 MPa) with a dissolved oxygen concentration of 5 mg/L. Regenerated GAC samples were evaluated in terms of adsorption capacity, BET surface area, pore volume, and average pore size. After four adsorption-regeneration cycles, using supercritical water (SCW) regeneration, the average adsorption capacity of regenerated GAC was found to be 90% of that of virgin GAC. Although a slightly higher adsorption capacity was achieved for regeneration with degassed water, the overall impact of dissolved oxygen was insignificant. The high adsorption capacity achieved for SCW was not observed for subcritical water regeneration. After four adsorption-regeneration cycles, only 67% of the original adsorption capacity was restored. The better results observed for SCW, as compared to subcritical water, were related to two factors. First, the higher regeneration temperatures of SCW resulted in increased thermal desorption. Second, the increased solubility of organic compounds and enhanced mass transfer rates in SCW resulted in a more efficient extraction process.

• Research Organization: Texas Univ., Dept. of Engineering, Austin, TX (United States)
• OSTI ID: 6342509
• Report Number(s): AD-A-362534/XAB
• Resource Relation: Other Information: Thesis
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ACTIVATED CARBON
ACTIVATED SLUDGE PROCESS
HYDROTHERMAL ALTERATION
PHENOLS
REGENERATION
SORPTIVE PROPERTIES
SUPERCRITICAL GAS EXTRACTION
ADSORBENTS
AROMATICS
CARBON
ELEMENTS
EXTRACTION
HYDROXY COMPOUNDS
MANAGEMENT
NONMETALS
ORGANIC COMPOUNDS
PROCESSING
SEPARATION PROCESSES
SOLVENT EXTRACTION
SURFACE PROPERTIES
WASTE MANAGEMENT
WASTE PROCESSING
320305* - Energy Conservation
Consumption
& Utilization- Industrial & Agricultural Processes- Industrial Waste Management
320604 - Energy Conservation
Consumption
& Utilization- Municipalities & Community Systems- Municipal Waste Management- (1980-)