Adsorption and biodegradation of high explosives on granular activated carbon
Adsorption to granular activated carbon (GAC) is an effective method for removing high explosives (HE) compounds from water, but no permanent treatment is achieved. An off-line bioregeneration system, which combines adsorption and biodegradation, is being developed to reduce GAC usage rates and destroy RDX and HMX. Desorption is often the limiting mass transfer mechanism in bioregeneration systems; thus, two cosolvents, four surfactants, and two cyclodextrins were considered for improving desorption of RDX and HMX. In batch experiments, about 3% of the adsorbed RDX was desorbed over 11 days using buggered water as the desorption fluid. In comparison, about 96% of the RDX was extracted from the GAC by acetonitrile. Ethanol and methanol were both effective in desorbing RDX and HMX. Sodium dodecyl sulfate (SDS), an anionic surfactant, desorbed 56.4% of the RDX at a concentration of 500 mg SDS/L. Cyclodextrins were marginally more effective than water. Continuous operation of a sequencing batch reactor (SBR) has effectively treated both contaminants. In an SBR that was operated with 4-day cycles for 72 days, mixed cultures consistently reduced RDX concentrations from 1 mg/L to non-detectable levels and HMX from 0.6 mg/L to 0.4 mg/L over each cycle. When removal from groundwater by adsorption is combined with enhanced desorption and subsequent biological treatment, the overall process is expected to effectively increase the GAC service life and provide a permanent treatment method for RDX and HMX.
- Research Organization:
- Univ. of Texas, Austin, TX (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC04-95AL85832
- OSTI ID:
- 20014774
- Resource Relation:
- Conference: ASCE-CSCE 1999 National Conference on Environmental Engineering, Norfolk, VA (US), 07/25/1999--07/28/1999; Other Information: PBD: 1999; Related Information: In: Environmental engineering 1999, by Schafran, G.C. [ed.], 936 pages.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mathematical model of the interaction between adsorption and biodegradation on granular activated carbon at low substrate concentrations
Granular activated carbon (GAC) system performance capabilities and optimization. Final report, August 1984-February 1987