Role of Microbial Metabolism and Cometabolism in Treating Mixtures of Biodegradable and Nonbiodegradable Chemicals in Granular Activated Carbon Columns

EPA Grant Number: R826170
Title: Role of Microbial Metabolism and Cometabolism in Treating Mixtures of Biodegradable and Nonbiodegradable Chemicals in Granular Activated Carbon Columns
Investigators: Speitel, Gerald E.
Institution: The University of Texas at Austin
EPA Project Officer: Lasat, Mitch
Project Period: December 1, 1997 through November 30, 2000
Project Amount: $304,688
RFA: Exploratory Research - Environmental Engineering (1997) RFA Text |  Recipients Lists
Research Category: Engineering and Environmental Chemistry , Land and Waste Management


Granular activated carbon (GAC) is widely used to treat water contaminated with synthetic organic chemicals (SOCs). Practically no information is available on combining adsorption and biodegradation to treat mixtures of biodegradable and nonbiodegradable SOCs, a very common problem. Biodegradation can increase the GAC service life and improve process performance relative to adsorption alone. This research seeks to 1) develop a better understanding of the effect of biodegradation on the service life of GAC columns, 2) identify conditions where metabolism of SOCs is advantageous, and 3) identify conditions where cometabolism of SOCs is advantageous.


The objectives will be achieved by an experimental program, complemented by mathematical modeling. SOCs over a broad range of characteristics will be studied from among the chemicals of current concern. Most experiments will involve two-component mixtures of a biodegradable and nonbiodegradable SOC. Typical GAC columns consist of three zones: exhausted GAC, mass transfer, and virgin GAC zones. All three are important to the success of biodegradation/ adsorption systems in different ways. To discern the contribution of each zone, column experiments will be conducted with exhausted GAC zones only, mass transfer zones only, and complete GAC columns. Gas chromatography and radiochemical techniques with 14C-SOCs will be used to track the fate of both SOCs. Cometabolism is a technique for biodegrading SOCs that are, in a traditional sense, nonbiode-gradable. No research has been done on cometabolism in GAC columns; therefore, preliminary experiments will be run to identify appropriate growth chemicals to stimulate cometabolism, prior to column experiments. Supporting experiments will measure desorption, displacement, and irreversible adsorption, which mainly affect bioregeneration of the GAC. Also, various equilibrium and kinetic parameters will be measured to support experimental design, data analysis, and modeling. Two existing biodegradation/adsorption models will be used, a simple equilibrium model and a sophisticated kinetic model. The models will provide a framework for synthesizing the experimental results into general observations on the applicability of biodegradation/adsorption systems for the treatment of mixtures.

Expected Results:

This research will fill a significant gap in our knowledge about GAC treatment, a gap that has economic, process performance, and health ramifications. Biodegradation/ adsorption systems are potentially less costly because the GAC service life can be longer than with adsorption alone. Ignorance of the process fundamentals has stymied technological advances beyond the current practice of considering only adsorption. This work will provide the fundamental information needed to stimulate innovation in treating mixtures of biodegradable and nonbiodegradable SOCs. This research will develop the a comprehensive experimental database on the performance of biodegradation/ adsorption systems in treating mixtures of biodegradable and nonbiodegradable SOCs, and will provide guidance on when biodegradation is attractive relative to adsorption alone and to what extent the GAC service life can be increased. The first data on cometabolism in GAC columns will be developed, and further testing and verification of the two computer simulation models will be possible. With this research, sufficient data will be available to assess biodegradation/adsorption systems with confidence and to indicate under what circumstances they are competitive with other treatment processes.

Publications and Presentations:

Publications have been submitted on this project: View all 9 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

water, adsorption, bioregeneration, bioremediation, innovative technology, synthetic organic chemicals., RFA, Scientific Discipline, Water, Environmental Chemistry, Wastewater, Bioremediation, Ecological Risk Assessment, Environmental Engineering, fate and transport, biodegradation, cometabolism, gas chromatography, bioregeneration, kinetic studies, granular activated carbon, water quality, mathematical modeling, water treatment

Relevant Websites: EPA icon

Progress and Final Reports:

  • 1998 Progress Report
  • 1999 Progress Report
  • Final Report