Kinetic analysis of simultaneous 2,4-dinitrotoluene (DNT) and 2,6-DNT biodegradation in an aerobic fluidized-bed biofilm reactor

Abstract

We previously reported on the mineralization of 2,4‐dinitrotoluene (2,4‐DNT) and 2,6‐dinitrotoluene (2,6‐DNT) in an aerobic fluidized‐bed bioreactor (FBBR) (Lendenmann et al. 1998 Environ Sci Technol 32:82–87). The current study examines the kinetics of 2,4‐DNT and 2,6‐DNT mineralization at increasing loading rates in the FBBR with the goal of obtaining system‐independent kinetic parameters. At each steady state, the FBBR was subjected to a set of transient load experiments in which substrate flux in the biofilm and bulk substrate concentrations were measured. The pseudo‐steady‐state data were used to estimate the biokinetic parameters for 2,4‐DNT and 2,6‐DNT removal using a mechanistic mathematical biofilm model and a routine that minimized the sum of the squared residuals (RSS). Estimated kinetic parameters varied slightly for each steady‐state; retrieved parameters for qm were 0.83 to 0.98 g DNT/g XCOD d for 2,4‐DNT removal and 0.14 to 0.33 g DNT/g XCOD d for 2,6‐DNT removal. Ks values for 2,4‐DNT removal (0.029 to 0.36 g DNT/m3) were consistently lower than Ks values for 2,6‐DNT removal (0.21 to 0.84 g DNT/m3). A new approach was introduced to estimate the fundamental biofilm kinetic parameter S *italicb,min from steady‐state performance information. Values of S *italicb,min indicated that the FBBR performance was limited by growth potential. Adequate performance of the examined FBBR technology at higher loading rates will depend on an improvement in the growth potential. The obtained kinetic parameters, qm, Ks, and S *italicb,min, can be used to aid in the design of aerobic FBBRs treating waters containing DNT mixtures. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 63: 642–653, 1999.

Reduction of polynitroaromatic compounds: the bacterial nitroreductases

“…(Boopathy, 1994;Boopathy & Kulpa, 1994), Desulfovibrio sp. (Boopathy & Kulpa, anaerobic systems have been used for remediation of TNT and other polynitroaromatic compounds, including static pile and windrow composting, bioslurry, and phytoremediation (Funk et al, 1993;Smets et al, 1999;Hawari et al, 2000a;Peres & Agathos, 2000;Rodgers & Bunce, 2001;Zhang et al, 2001;Lewis et al, 2004;Schrader & Hess, 2004). Transgenic plants bearing bacterial nitroreductase genes, or combined treatments with both plants and microorganisms able to degrade nitroaromatic compounds, are expected to be used as efficient decontaminating procedures in the near future (French et al, 1999;Hannink et al, 2001Hannink et al, , 2002Kurumata et al, 2005).…”

Aerobic biodegradation of 2,4-DNT and 2,6-DNT: Performance characteristics and biofilm composition changes in continuous packed-bed bioreactors

“…As a result, ex situ biodegradation of DNT-contaminated soils and ground water has been pursued. Under appropriate operating conditions, the DNTs can serve as sole sources of carbon, nitrogen, and energy for the microorganisms [3,9], and even complete degradation of different nitrotoluenes when present together has been reported [10]. Several recent studies have shown that microorganisms demonstrate an ability to adapt to higher concentrations of DNTs [11,12].…”

Anaerobic reduction of 2,6‐dinitrotoluene by Shewanella oneidensis MR‐1: Roles of Mtr respiratory pathway and NfnB

“…Many microbial strains, such as Burkholderia cepacia strain JS850 and Hydrogenophaga palleronii strain JS863, can grow on 2,6-DNT as their sole carbon and nitrogen source (Nishino et al, 2000). Some mixed enrichment cultures in freshwater and biofilm reactors have also been reported to biodegrade 2,6-DNT (Lendenmann et al, 1998;Paca et al, 2008;Pesce and Wunderlin, 1997;Smets et al, 1999). However, due to the electron-deficient property of aromatic rings resulting from the substitution of nitro group, DNT is a biorefractory compound and its biodegradation efficiency is usually not high (Cruz-Uribe and Rorrer, 2006;Leungsakul et al, 2005Leungsakul et al, , 2006.…”