Grantee Research Project Results
1998 Progress Report: The Effect of In Situ Biosurfactant Production on Hydrocarbon Biodegradation
EPA Grant Number: R826161Title: The Effect of In Situ Biosurfactant Production on Hydrocarbon Biodegradation
Investigators: Strevett, Keith A. , Sabatini, David A. , Tanner, R. , Knox, Robert
Current Investigators: Strevett, Keith A. , Sabatini, David A. , Everett, Jess , Tanner, R.
Institution: University of Oklahoma
EPA Project Officer: Aja, Hayley
Project Period: March 10, 1998 through March 9, 2001 (Extended to September 9, 2001)
Project Period Covered by this Report: March 10, 1998 through March 9, 1999
Project Amount: $323,072
RFA: Exploratory Research - Environmental Engineering (1997) RFA Text | Recipients Lists
Research Category: Land and Waste Management , Safer Chemicals
Objective:
The goal of this research is to develop a mechanistic and innovative methodology that can effectively predict and describe anaerobic and aerobic biodegradability of hydrocarbons as impacted by biosurfactants.Progress Summary:
This study derives from the fundamental hypothesis that bioavailability of hydrocarbons in mixed chemical matrices can be described based on the individual interactions occurring in the environment. These interactions may include soil-chemical, soil-microorganism, soil-biosurfactant, microorganism-biosurfactant, and others. The biological removal of toluene under both anaerobic and aerobic metabolism in the presence of a biosurfactant-producing microorganism was accomplished within the first year. Under aerobic conditions, in situ production of rhamnolipid was decreased in the presence of toluene, resulting in a drop of surface tension from 69 to 42 dyne/cm, compared with a biosurfactant-producing mutant (no same strain without biosurfactant-producing capability) that corresponded to a surface tension drop from 69 to 65 dyne/cm. In the absence of toluene, the biosurfactant production decreased the surface tension from 72 to 25 dyne/cm at a critical micelle concentration of 19 mg/L.The deviation of nonideality in Raoult's Law also was investigated. Toluene solubility in the presence of nonaqueous phase liquid (NAPL) was then investigated. Triplicates of a total liquid volume of 40 mL with 4 mL NAPL was used. The NAPL consists of toluene:hexadecane: phenanthrene (T:H:P) at molar ratios of 1:1:1, 1:1:2, 1:2:1, and 2:1:1. Toluene solubility was determined as above. The toluene concentration, in mg/L, of 154.3?8.7, 171.3?15.5, 99.0?4.3 and 226.5?21.3 for T:H:P: molar ratios of 1:1:1, 1:1:2, 1:2:1, and 2:1:1, respectively, were determined. The server departure from Raoult's Law (for T:H:P molar ratios of 1:1:1, 1:1:2, 1:2:1, and 2:1:1 is 105, 78, 78, and 78 mg/L, respectively) resulted from the higher specific gravity of phenanthrene. Within the vials, phenanthrene separated from the light NAPL and possibly brought some of the hexadecane and toluene to the bottom in the form of a dense NAPL. Toluene solubility with varying NAPL:water ratios was used to determine the extent of Raoult's Law deviation. Using a constant NAPL composition of T:H:P:1:2:1, 45 mL EPA vials were set up for a total liquid volume of 40 mL with NAPL volumes of 4, 6, 7, 10, and 12 mL. At 72 hours, the toluene concentration, in mg/L, for the NAPL/water ratio of 4/36, 6/34, 8/32, 10/30, and 12/28 were 113.0?8.2, 120.6?12.4, 132.2?17.5, 131.6?10.9, and 114.3?22.3, respectively. There was no significant difference among these values (95 percent C.I., t-test); therefore, the Raoult's Law deviation is not associated with a low NAPL volume.
Future Activities:
Investigation on the impact of biosurfactants on Raoult's Law for a light NAPL and resulting interfacial thermodynamics. Biotic studies of phenanthrene and hexadecane degradation in the presence of JF-2 biosurfactant under anaerobic and aerobic conditions.Journal Articles:
No journal articles submitted with this report: View all 3 publications for this projectSupplemental Keywords:
applied biosurfactant technology, microbial surface thermodynamics, biodegradation kinetics, environment restoration, toluene, phenanthrene, hexadecane, JP-4, rhamnolipid, lipopeptide., Scientific Discipline, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, Bioremediation, Ecology and Ecosystems, 33/50, Environmental Engineering, aerobic degradation, bioremediation model, Toluene, biodegradation, chemical transport, biokinetic model, contaminant release, biosurfactant specifity, surface thermodynamicsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.