+ Site Statistics
References:
54,258,434
Abstracts:
29,560,870
PMIDs:
28,072,757
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Translate
+ Recently Requested

Simulating biodegradation of toluene in sand column experiments at the macroscopic and pore-level scale for aerobic and denitrifying conditions



Simulating biodegradation of toluene in sand column experiments at the macroscopic and pore-level scale for aerobic and denitrifying conditions



Advances in water resources 27(4): 335-348



Heterotropic bacteria can degrade organic substrates utilizing different terminal electron acceptors. The sequence of electron acceptor utilization depends on the energy yield of the individual reaction pathway, which decreases as the redox potential decreases. Due to these differences in energy yield, and an inhibiting activity of oxygen on some enzymatic processes, the simultaneous utilization of oxygen and nitrate as terminal electron acceptors may not occur for many degradation processes, unless the oxygen concentration falls below a given threshold level (about 0.2 mg/l).Two sand column experiments were conducted, with toluene as the carbon source, and showed an apparent simultaneous utilization of oxygen and nitrate as electron acceptors in regions where the oxygen concentration was significantly higher (1.1 mg/l) than the above mentioned threshold concentration. Results from aerobic and anaerobic plate-count analyses showed growth of both aerobes and denitrifiers in the zone of the column where simultaneous utilization of oxygen and nitrate was observed. From these observations, it was postulated that the porous media contained oxygen-free microlocations where the denitrifiers were able to degrade the toluene.To simulate the observed dynamics, a dual biofilm model was implemented. This model formulation assumes that the biofilm is composed of two distinct layers, where the outer layer is colonized by aerobic bacteria and the inner layer by denitrifying bacteria. The thickness of the aerobic layer is such that oxygen is depleted at the boundary of these two layers, resulting in oxygen-free microlocations that allows denitrification to proceed, even though oxygen is still present in the bulk fluid phase. The model simulations compared well to the experimental profiles. Model analyses indicated that changes in physical, chemical, and hydrologic parameters could change the length and location of the zone where at the macroscopic level, oxygen and nitrate are utilized simultaneously. Comparisons of the proposed model to macroscopic modeling approaches showed that a dual biofilm model is able to describe the simultaneous utilization of oxygen and nitrate more accurately.

(PDF emailed within 0-6 h: $19.90)

Accession: 017037838

Download citation: RISBibTeXText

DOI: 10.1016/j.advwatres.2004.02.012


Related references

Simulating the biodegradation of toluene at the macroscopic and pore-level scale for aerobic and nitrate reducing conditions. Abstracts of Papers American Chemical Society 220(Part 1): ENVR 145, 2000

Biodegradation of benzene and toluene under enhanced denitrifying conditions. Acta Geologica Sinica (English Edition) 73(4): 447-451, 1999

Anaerobic biodegradation of toluene under denitrifying conditions in contaminated groundwater and soil. Journal Of Hazardous Materials. 45(2-3): 219-232, 1996

Column studies on BTEX biodegradation under microaerophilic and denitrifying conditions. Journal of Hazardous Materials 32(2-3): 195-214, 1992

Spatial distribution and physiological state of bacteria in a sand column experiment during the biodegradation of toluene. Water Research 41(10): 2089-2100, 2007

Biodegradation of three- and four-ring polycyclic aromatic hydrocarbons under aerobic and denitrifying conditions. Environmental Science & Technology. 32(17): 2633-2639,. 1, 1998

Biodegradation of vapor-phase toluene in unsaturated porous media: Column experiments. Environmental Pollution 211: 325-331, 2016

Effect of pore velocity on biodegradation of cis-dichloroethene (DCE) in column experiments. Biodegradation 21(3): 365-377, 2010

Biodegradation of free phytol by bacterial communities isolated from marine sediments under aerobic and denitrifying conditions. Applied and Environmental Microbiology 65(12): 5484-5492, 1999

Intrinsic biodegradation of toluene coupled to the microbial reduction of ferric iron: laboratory column experiments. Environmental Geology 42(6): 649-656, 2002

Aerobic biodegradation of benzene and toluene under hypersaline conditions at the Great Salt Plains, Oklahoma. Fems Microbiology Letters 245(2): 257-262, 2005

Biodegradation of polychlorinated biphenyls under aerobic and microaerophilic conditions by facultative denitrifying, microaerophilic bacteria. Abstracts of the General Meeting of the American Society for Microbiology 96(0): 419, 1996

Microbial growth and clogging in sand column experiments simulating artificial recharge of groundwater. Proceedings of the, 1998

Biodegradation of butterfat supplemented with surfactant and detergent formulation in bench-scale sand column biofilm systems. On site wastewater treatment Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Orlando, Florida, USA, 8-10 March, 1998: 371-379, 1998

Nonequilibrium sorption and aerobic biodegradation of dissolved alkylbenzenes during transport in aquifer material column experiments and evaluation of a coupled process model. Environmental Science & Technology 26(7): 1404-1410, 1992