1
|
Tatari K, Gülay A, Thamdrup B, Albrechtsen HJ, Smets BF. Challenges in using allylthiourea and chlorate as specific nitrification inhibitors. Chemosphere 2017. [PMID: 28505572 DOI: 10.1016/j2017.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Allylthiourea (ATU) and chlorate (ClO3-) are often used to selectively inhibit nitritation and nitratation. In this work we identified challenges with use of these compounds in inhibitory assays with filter material from a biological rapid sand filter for groundwater treatment. Inhibition was investigated in continuous-flow lab-scale columns, packed with filter material from a full-scale filter and supplied with NH4+ or NO2-. ATU concentrations of 0.1-0.5 mM interfered with the indophenol blue method for NH4+ quantification leading to underestimation of the measured NH4+ concentration. Interference was stronger at higher ATU levels and resulted in no NH4+ detection at 0.5 mM ATU. ClO3- at typical concentrations for inhibition assays (1-10 mM) inhibited nitratation by less than 6%, while nitritation was instead inhibited by 91% when NH4+ was supplied. On the other hand, nitratation was inhibited by 67-71% at 10-20 mM ClO3- when NO2- was supplied, suggesting significant nitratation inhibition at higher NO2- concentrations. No chlorite (ClO2-) was detected in the effluent, and thus we could not confirm that nitritation inhibition was caused by ClO3- reduction to ClO2-. In conclusion, ATU and ClO3- should be used with caution in inhibition assays, because analytical interference and poor selectivity for the targeted process may affect the experimental outcome and compromise result interpretation.
Collapse
Affiliation(s)
- K Tatari
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark
| | - A Gülay
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark
| | - B Thamdrup
- Nordic Center for Earth Evolution, Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - H-J Albrechtsen
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark
| | - B F Smets
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark.
| |
Collapse
|
2
|
Tatari K, Gülay A, Thamdrup B, Albrechtsen HJ, Smets BF. Challenges in using allylthiourea and chlorate as specific nitrification inhibitors. Chemosphere 2017; 182:301-305. [PMID: 28505572 DOI: 10.1016/j.chemosphere.2017.05.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 11/25/2016] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Allylthiourea (ATU) and chlorate (ClO3-) are often used to selectively inhibit nitritation and nitratation. In this work we identified challenges with use of these compounds in inhibitory assays with filter material from a biological rapid sand filter for groundwater treatment. Inhibition was investigated in continuous-flow lab-scale columns, packed with filter material from a full-scale filter and supplied with NH4+ or NO2-. ATU concentrations of 0.1-0.5 mM interfered with the indophenol blue method for NH4+ quantification leading to underestimation of the measured NH4+ concentration. Interference was stronger at higher ATU levels and resulted in no NH4+ detection at 0.5 mM ATU. ClO3- at typical concentrations for inhibition assays (1-10 mM) inhibited nitratation by less than 6%, while nitritation was instead inhibited by 91% when NH4+ was supplied. On the other hand, nitratation was inhibited by 67-71% at 10-20 mM ClO3- when NO2- was supplied, suggesting significant nitratation inhibition at higher NO2- concentrations. No chlorite (ClO2-) was detected in the effluent, and thus we could not confirm that nitritation inhibition was caused by ClO3- reduction to ClO2-. In conclusion, ATU and ClO3- should be used with caution in inhibition assays, because analytical interference and poor selectivity for the targeted process may affect the experimental outcome and compromise result interpretation.
Collapse
Affiliation(s)
- K Tatari
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark
| | - A Gülay
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark
| | - B Thamdrup
- Nordic Center for Earth Evolution, Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - H-J Albrechtsen
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark
| | - B F Smets
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lynby, Denmark.
| |
Collapse
|
3
|
Tatari K, Smets BF, Albrechtsen HJ. Depth investigation of rapid sand filters for drinking water production reveals strong stratification in nitrification biokinetic behavior. Water Res 2016; 101:402-410. [PMID: 27295615 DOI: 10.1016/j.watres.2016.04.073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 04/08/2016] [Accepted: 04/27/2016] [Indexed: 06/06/2023]
Abstract
The biokinetic behavior of NH4(+) removal was investigated at different depths of a rapid sand filter treating groundwater for drinking water preparation. Filter materials from the top, middle and bottom layers of a full-scale filter were exposed to various controlled NH4(+) loadings in a continuous-flow lab-scale assay. NH4(+) removal capacity, estimated from short term loading up-shifts, was at least 10 times higher in the top than in the middle and bottom filter layers, consistent with the stratification of Ammonium Oxidizing Bacteria (AOB). AOB density increased consistently with the NH4(+) removal rate, indicating their primarily role in nitrification under the imposed experimental conditions. The maximum AOB cell specific NH4(+) removal rate observed at the bottom was at least 3 times lower compared to the top and middle layers. Additionally, a significant up-shift capacity (4.6 and 3.5 times) was displayed from the top and middle layers, but not from the bottom layer at increased loading conditions. Hence, AOB with different physiological responses were active at the different depths. The biokinetic analysis predicted that despite the low NH4(+) removal capacity at the bottom layer, the entire filter is able to cope with a 4-fold instantaneous loading increase without compromising the effluent NH4(+). Ultimately, this filter up-shift capacity was limited by the density of AOB and their biokinetic behavior, both of which were strongly stratified.
Collapse
Affiliation(s)
- K Tatari
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800, Kgs. Lyngby, Denmark.
| | - B F Smets
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800, Kgs. Lyngby, Denmark
| | - H-J Albrechtsen
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800, Kgs. Lyngby, Denmark
| |
Collapse
|
4
|
Tatari K, Smets BF, Albrechtsen HJ. A novel bench-scale column assay to investigate site-specific nitrification biokinetics in biological rapid sand filters. Water Res 2013; 47:6380-6387. [PMID: 24091186 DOI: 10.1016/j.watres.2013.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 08/01/2013] [Accepted: 08/06/2013] [Indexed: 06/02/2023]
Abstract
A bench-scale assay was developed to obtain site-specific nitrification biokinetic information from biological rapid sand filters employed in groundwater treatment. The experimental set-up uses granular material subsampled from a full-scale filter, packed in a column, and operated with controlled and continuous hydraulic and ammonium loading. Flowrates and flow recirculation around the column are chosen to mimic full-scale hydrodynamic conditions, and minimize axial gradients. A reference ammonium loading rate is calculated based on the average loading experienced in the active zone of the full-scale filter. Effluent concentrations of ammonium are analyzed when the bench-scale column is subject to reference loading, from which removal rates are calculated. Subsequently, removal rates above the reference loading are measured by imposing short-term loading variations. A critical loading rate corresponding to the maximum removal rate can be inferred. The assay was successfully applied to characterize biokinetic behavior from a test rapid sand filter; removal rates at reference loading matched those observed from full-scale observations, while a maximum removal capacity of 6.9 g NH4(+)-N/m(3) packed sand/h could easily be determined at 7.5 g NH4(+)-N/m(3) packed sand/h. This assay, with conditions reflecting full-scale observations, and where the biological activity is subject to minimal physical disturbance, provides a simple and fast, yet powerful tool to gain insight in nitrification kinetics in rapid sand filters.
Collapse
Affiliation(s)
- K Tatari
- Department of Environmental Engineering, Technical University of Denmark, Miljøevej 113, 2800 Kgs. Lynby, Denmark.
| | | | | |
Collapse
|
5
|
Mutlu AG, Vangsgaard AK, Sin G, Smets BF. An operational protocol for facilitating start-up of single-stage autotrophic nitrogen-removing reactors based on process stoichiometry. Water Sci Technol 2013; 68:514-521. [PMID: 23925177 DOI: 10.2166/wst.2013.157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Start-up and operation of single-stage nitritation-anammox sequencing batch reactors (SBRs) for completely autotrophic nitrogen removal can be challenging and far from trivial. In this study, a step-wise procedure is developed based on stoichiometric analysis of the process performance from nitrogen species measurements to systematically guide start-up and normal operation efforts (instead of trial and error). The procedure is successfully applied to laboratory-scale SBRs for start-up and maintained operation over an 8-month period. This analysis can serve as a strong decision-making tool to take appropriate actions with respect to reactor operation to accelerate start-up or ensure high-rate N removal via the nitritation-anammox pathway.
Collapse
Affiliation(s)
- A G Mutlu
- Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark.
| | | | | | | |
Collapse
|
6
|
Attard E, Poly F, Commeaux C, Laurent F, Terada A, Smets BF, Recous S, Roux XL. Shifts betweenNitrospira- andNitrobacter-like nitrite oxidizers underlie the response of soil potential nitrite oxidation to changes in tillage practices. Environ Microbiol 2010; 12:315-26. [DOI: 10.1111/j.1462-2920.2009.02070.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
7
|
Vlaeminck SE, Terada A, Carballa M, De Clippeleir H, Boon N, Smets BF, Verstraete W. Fluorescence in situ hybridization (FISH) to elucidate structure and diversity in granular biomass for the treatment of nitrogenous wastewater. Commun Agric Appl Biol Sci 2008; 73:43-47. [PMID: 18831243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- S E Vlaeminck
- Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, BE-9000 Gent, Belgium
| | | | | | | | | | | | | |
Collapse
|
8
|
Guisasola A, Chandran K, Smets BF, Baeza JA, Carrera J, Lafuente J. Observation and mathematical description of the acceleration phenomenon in batch respirograms associated with ammonium oxidation. Water Sci Technol 2006; 54:181-8. [PMID: 17163027 DOI: 10.2166/wst.2006.718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Two-step nitrification models are generally calibrated using short-term respirometric batch experiments. Important discrepancies appear between model predictions and experimental observations just after the pulse addition since a fast transient in the OUR profile is experimentally observed. Acceleration of the OUR appears ongoing between the substrate addition and attainment of the maximum OUR value. Among the several phenomena that could contribute to this observation, the most probable cause is the limitation of reducing equivalents required for maximal ammonia monooxygenase activity at the time of substrate addition. Ignoring acceleration would result in large parameter estimation errors from respirometric batch experiments. This work proposes a simple methodology to successfully describe (not to explain) the acceleration phenomenon estimating only two parameters. This methodology consists of introducing a Gaussian-like expression in the model.
Collapse
Affiliation(s)
- A Guisasola
- Department of Chemical Engineering, ETSE, Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | | | | | | | | | | |
Collapse
|
9
|
Morrow JB, Stratton R, Yang HH, Smets BF, Grasso D. Macro- and nanoscale observations of adhesive behavior for several E. coli strains (O157:H7 and environmental isolates) on mineral surfaces. Environ Sci Technol 2005; 39:6395-404. [PMID: 16190192 DOI: 10.1021/es0500815] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Subsurface biobarriers can be conceived to attenuate the migration of pathogens by adhesion to mineral surfaces. Candidate biobarrier materials of varied surface characteristics (dolomite, alpha-alumina, silica, pyrophyllite, and Pyrax (a composite form of pyrophyllite, mica, and silica)) were tested for Escherichia coli adhesive capacity in macroscale continuous-flow columns. Atomic force microscopy (AFM) was used to determine nanoscale interaction energies. Predicted attractive interaction energies correlated well with macroscale adhesive behavior for tested E. coli strains. AFM measurements confirmed ExDLVO model predictions of attachment in the primary minima for E. coli O157:H7 and two environmental isolates E. coli (UCFL339 and UCFL-348) with MOPS conditioned Pyrax. In macroscale column experiments, pyrophyllite and Pyrax demonstrated significantly higher bacterial retention, higher deposition coefficients and lower initial cell breakthrough values for E. coli O157:H7 than did alpha-alumina, silica, or dolomite (pyrophyllite, 0.93, 3.56 h(-1), 3.2% ODo; Pyrax, 0.95, 3.73 h(-1), 2.8% ODo; alpha-alumina, 0.74, 1.60 h(-1), 33% ODo; silica, 0.63, 0.43 h(-1), 73% ODo; and dolomite, 0.33, 0.17 h(-1), 89% ODo, respectively). Bacterial hydrophilicity impacted cell retention in Pyrax columns with the relatively hydrophobic E. coli isolate UCFL-339 (0.99, 6.13 h(-1), 0.4% ODo) retained better than the more hydrophilic E. coli isolate UCFL348 (0.94, 3.70 h(-1), 3.6% ODo). The strong adhesive behavior of Pyrax was attributed to the hydrophobic (deltaGiwi = -32.4 mJ/m2) pyrophyllite component of the mineral. Vicinal water appears poised between the bacterial and the mineral surface during initial attachment. Overall, observed behavior of the various E. coli strains and the selected mineral surfaces was consistent with surface analyses, conducted at both the macro- and nanoscale.
Collapse
Affiliation(s)
- J B Morrow
- Environmental Engineering Program and Microbiology Program, University of Connecticut, Storrs, Connecticut 06269, USA
| | | | | | | | | |
Collapse
|
10
|
Chandran K, Hu Z, Smets BF. Applicability of an extant batch respirometric assay in describing dynamics of ammonia and nitrite oxidation in a nitrifying bioreactor. Water Sci Technol 2005; 52:503-8. [PMID: 16459827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Several techniques have been proposed for biokinetic estimation of nitrification. Recently, an extant respirometric assay has been presented that yields kinetic parameters for both nitrification steps with minimal physiological change to the microorganisms during the assay. Herein, the ability of biokinetic parameter estimates from the extant respirometric assay to adequately describe concurrently obtained NH4+-N and NO(2-)-N substrate depletion profiles is evaluated. Based on our results, in general, the substrate depletion profiles resulted in a higher estimate of the maximum specific growth rate coefficient, micro(max) for both NH4+-N to NO(2-)-N oxidation and NO(2-)-N to NO(3-)-N oxidation compared to estimates from the extant respirograms. The trends in the kinetic parameter estimates from the different biokinetic estimation techniques are paralleled in the nature of substrate depletion profiles obtained from best-fit parameters. Based on a visual inspection, in general, best-fit parameters from optimally designed complete respirograms provided a better description of the substrate depletion profiles than estimates from isolated respirograms. Nevertheless, the sum of the squared errors for the best-fit respirometry based parameters was outside the 95% joint confidence interval computed for the best-fit substrate depletion based parameters. Notwithstanding the difference in kinetic parameter estimates determined in this study, the different biokinetic estimation techniques still are close to estimates reported in literature. Additional parameter identifiability and sensitivity analysis of parameters from substrate depletion assays revealed high precision of parameters and high parameter correlation. Although biokinetic estimation via automated extant respirometry is far more facile than via manual substrate depletion measurements, additional sensitivity analyses are needed to test the impact of differences in the resulting parameter values on continuous reactor performance.
Collapse
Affiliation(s)
- K Chandran
- Environmental Engineering Program, University of Connecticut, 261 Glenbrook Road, U-37, Storrs, CT 06269, USA
| | | | | |
Collapse
|
11
|
Seagren EA, Kim H, Smets BF. Identifiability and retrievability of unique parameters describing intrinsic Andrews kinetics. Appl Microbiol Biotechnol 2003; 61:314-22. [PMID: 12743760 DOI: 10.1007/s00253-002-1220-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2002] [Revised: 11/27/2002] [Accepted: 12/06/2002] [Indexed: 10/25/2022]
Abstract
A key factor contributing to the variability in the microbial kinetic parameters reported from batch assays is parameter identifiability, i.e., the ability of the mathematical routine used for parameter estimation to provide unique estimates of the individual parameter values. This work encompassed a three-part evaluation of the parameter identifiability of intrinsic kinetic parameters describing the Andrews growth model that are obtained from batch assays. First, a parameter identifiability analysis was conducted by visually inspecting the sensitivity equations for the Andrews growth model. Second, the practical retrievability of the parameters in the presence of experimental error was evaluated for the parameter estimation routine used. Third, the results of these analyses were tested using an example data set from the literature for a self-inhibitory substrate. The general trends from these analyses were consistent and indicated that it is very difficult, if not impossible, to simultaneously obtain a unique set of estimates of intrinsic kinetic parameters for the Andrews growth model using data from a single batch experiment.
Collapse
Affiliation(s)
- E A Seagren
- Department of Civil and Environmental Engineering, University of Maryland, College Park 20742, USA.
| | | | | |
Collapse
|
12
|
Abstract
Transformation of 2,4-dinitrotoluene (2,4-DNT) by Alcaligenes JS867 under varying degrees of oxygen limitation was examined. Complete 2,4-DNT removal was observed under oxygen excess with near stoichiometric release (83%) of nitrite. Average kinetic parameters were estimated based on a dual-Monod biokinetic model with 2,4-DNT and O2 as growth limiting substrates. The negative impact of nitrite accumulation on the reaction rate was adequately described by inclusion of a noncompetitive inhibition term for NO2-. Under aerobic conditions, mumax, KsDNT, and KiNO were 0.058 (0.004)hr(-1), 3.3(+/-1.3) mg 2,4-DNT/L, and 1.2(+/-0.2)hr(-1), respectively. At increasing oxygen limitation, rates of 2,4-DNT disappearance and nitrite production decreased and incomplete removal of 2,4-DNT commenced. JS867 was able to use NO2- as a terminal electron acceptor when grown on glucose or succinate under anaerobic conditions. However, during growth on 2,4-DNT and under O2-limited conditions, JS867 did not use released nitrite as electron acceptor. The nearly constant molar ratios of DNT removed over NO2- released under various degrees of oxygen limitation suggested that oxygenolytic denitration pathways continued. No evidence of nitroreduction was obtained under the examined oligotrophic conditions. JS867 displayed a high affinity for oxygen consumption with K(SO2) value of 0.285(+/-0.198) mg O2/L. Our results indicate that under oligotrophic conditions with 2,4-DNT as dominant carbon source, oxygen availability and nitrite accumulation may limit 2,4-DNT biomineralization, but the accumulation of reduced 2,4-DNT transformation products will be small.
Collapse
Affiliation(s)
- B F Smets
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs 06269-2037, USA.
| | | |
Collapse
|
13
|
Affiliation(s)
- B F Smets
- Environmental Engineering and Microbiology Programs, University of Connecticut, USA
| | | | | |
Collapse
|
14
|
Dries J, Smets BF. Transformation and mineralization of benzo[a]pyrene by microbial cultures enriched on mixtures of three- and four-ring polycyclic aromatic hydrocarbons. J Ind Microbiol Biotechnol 2002. [DOI: 10.1038/sj.jim.7000211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
15
|
Dries J, Smets BF. Transformation and mineralization of benzo[a]pyrene by microbial cultures enriched on mixtures of three- and four-ring polycyclic aromatic hydrocarbons. J Ind Microbiol Biotechnol 2002; 28:70-3. [PMID: 12074054 DOI: 10.1038/sj/jim/7000211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microorganisms originating from a soil contaminated by low levels of polycyclic aromatic hydrocarbons (PAHs) were enriched with three- and four-ring PAHs as primary substrates in the presence of benzo[a]pyrene (BaP). Most enrichment cultures, isolated in the presence or absence of a sorptive matrix, significantly transformed BaP. Evidence of BaP mineralization was obtained with cultures enriched on phenanthrene and anthracene. Our findings supplement literature data suggesting the wide occurrence of microbial activity against BaP.
Collapse
Affiliation(s)
- J Dries
- Environmental Engineering Program, University of Connecticut, Storrs 06269-2037, USA
| | | |
Collapse
|
16
|
Affiliation(s)
- B F Smets
- Laboratory of Microbial Ecology and Technology, Ghent University, Belgium
| | | | | |
Collapse
|
17
|
Johnson GR, Smets BF, Spain JC. Oxidative transformation of aminodinitrotoluene isomers by multicomponent dioxygenases. Appl Environ Microbiol 2001; 67:5460-6. [PMID: 11722893 PMCID: PMC93330 DOI: 10.1128/aem.67.12.5460-5466.2001] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2001] [Accepted: 09/11/2001] [Indexed: 11/20/2022] Open
Abstract
The electron-withdrawing nitro substituents of 2,4,6-trinitrotoluene (TNT) make the aromatic ring highly resistant to oxidative transformation. The typical biological transformation of TNT involves reduction of one or more of the nitro groups of the ring to produce the corresponding amine. Reduction of a single nitro substituent of TNT to an amino substituent increases the electron density of the aromatic nucleus considerably. The comparatively electron-dense nuclei of the aminodinitrotoluene (ADNT) isomers would be expected to be more susceptible to oxygenase attack than TNT. The hypothesis was tested by evaluating three nitroarene dioxygenases for the ability to hydroxylate the ADNT isomers. The predominant reaction was dioxygenation of the ring to yield nitrite and the corresponding aminomethylnitrocatechol. A secondary reaction was benzylic monooxygenation to form aminodinitrobenzyl alcohol. The substrate preferences and catalytic specificities of the three enzymes differed considerably. The discovery that the ADNT isomers are substrates for the nitroarene dioxygenases reveals the potential for extensive bacterial transformation of TNT under aerobic conditions.
Collapse
Affiliation(s)
- G R Johnson
- Air Force Research Laboratory, Tyndall Air Force Base, Florida 32403, USA
| | | | | |
Collapse
|
18
|
Abstract
Kinetic characterization of biological processes via batch respirometry requires an accurate estimate of the biomass yield coefficient because it provides the stoichiometric link between biomass synthesis, substrate consumption and oxygen uptake. Expressions for biomass yield coefficients describing autotrophic ammonia and nitrite oxidation were derived from a mechanistically based electron balanced equation. We demonstrate that applying the conventional expression used to calculate the heterotrophic biomass yield results in erroneous estimates for the autotrophic biomass yield. Yield coefficients for autotrophic NH4(+)-N to NO2(-)-N oxidation and NH4(+)-N to NO3(-)-N oxidation were overestimated by 27 to 36%. Due to correlation between the maximum specific growth rate and the biomass yield, the error in yield values propagated in 30 to 40% overestimates of the maximum specific growth rate coefficient for NH4(+)-N oxidation determined from batch respirograms. Therefore, it is essential to employ the correct expression to estimate the autotrophic biomass yield coefficient from batch respirograms due its inadvertent impact on subsequent parameter estimation.
Collapse
Affiliation(s)
- K Chandran
- Environmental Engineering Program, University of Connecticut, Storrs 06269-2037, USA
| | | |
Collapse
|
19
|
Yang Y, Ratté D, Smets BF, Pignatello JJ, Grasso D. Mobilization of soil organic matter by complexing agents and implications for polycyclic aromatic hydrocarbon desorption. Chemosphere 2001; 43:1013-1021. [PMID: 11368215 DOI: 10.1016/s0045-6535(00)00498-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Complexing agents are frequently used in treatment technologies to remediate soils, sediments and wastes contaminated with toxic metals. The present study reports results that indicate that the rate and extent of soil organic matter (SOM) as represented by dissolved natural organic carbon (DNOC) and polycyclic aromatic hydrocarbon (PAH) desorption from a contaminated soil from a manufactured gas plant (MGP) site can be significantly enhanced with the aid of complexing agents. Desorption of DNOC and PAH compounds was pH dependent, with minimal release occurring at pH 2-3 and maximal release at pH 7-8. At pH-6, chelate solutions were shown to dissolve large amounts of humic substances from the soil compared to controls. The complexing agents mobilized polyvalent metal ions, particularly Fe and Al from the soil. Metal ion chelation may disrupt humic (metal ion)-mineral linkages, resulting in mobilization of SOM and accompanying PAH molecules into the aqueous phase; and/or reduce the degree of cross-linking in the soil organic matter phase, which could accelerate PAH diffusion.
Collapse
Affiliation(s)
- Y Yang
- Environmental Engineering Program, University of Connecticut, Storrs 06269-2037, USA
| | | | | | | | | |
Collapse
|
20
|
Chandran K, Smets BF. Applicability of two-step models in estimating nitrification kinetics from batch respirograms under different relative dynamics of ammonia and nitrite oxidation. Biotechnol Bioeng 2000; 70:54-64. [PMID: 10940863 DOI: 10.1002/1097-0290(20001005)70:1<54::aid-bit7>3.0.co;2-h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A mechanistically based nitrification model was formulated to facilitate determination of both NH(4)(+)-N to NO(2)(-)-N and NO(2)(-)-N to NO(3)(-)-N oxidation kinetics from a single NH(4)(+)-N to NO(3)(-)-N batch-oxidation profile by explicitly considering the kinetics of each oxidation step. The developed model incorporated a novel convention for expressing the concentrations of nitrogen species in terms of their nitrogenous oxygen demand (NOD). Stoichiometric coefficients relating nitrogen removal, oxygen uptake, and biomass synthesis were derived from an electron-balanced equation.%A parameter identifiability analysis of the developed two-step model revealed a decrease in correlation and an increase in the precision of the kinetic parameter estimates when NO(2)(-)-N oxidation kinetics became increasingly rate-limiting. These findings demonstrate that two-step models describe nitrification kinetics adequately only when NH(4)(+)-N to NO(3)(-)-N oxidation profiles contain sufficient information pertaining to both nitrification steps. Thus, the rate-determining step in overall nitrification must be identified before applying conventionally used models to describe batch nitrification respirograms.
Collapse
Affiliation(s)
- K Chandran
- Environmental Engineering Program, University of Connecticut, 261 Glenbrook Road, Storrs, Connecticut 06269-2037, USA
| | | |
Collapse
|
21
|
Abstract
A sorptive slurry bioscrubber adds powdered activated carbon (PAC) to a conventional suspended-growth bioscrubber. The activated carbon increases pollutant removal from the gas phase due to adsorption on carbon. The carbon is bioregenerated in the oxidation reactor and recycled to the scrubbing column. A three-stage, conventional bioscrubber was tested with and without carbon. The experiments showed that the PAC improved the removal efficiency of the system and that bioregeneration occurred. At an inlet gas-phase acetone concentration of 50 ppmv, the steady-state removal increased from 88 to 95% when activated carbon was added to the biological slurry.
Collapse
Affiliation(s)
- R E Hammervold
- Department of Environmental Engineering and Science, Clemson University, Anderson, South Carolina, USA
| | | | | | | |
Collapse
|
22
|
Chandran K, Smets BF. Single-step nitrification models erroneously describe batch ammonia oxidation profiles when nitrite oxidation becomes rate limiting. Biotechnol Bioeng 2000; 68:396-406. [PMID: 10745208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Nitrification involves the sequential biological oxidation of reduced nitrogen species such as ammonium-nitrogen (NH(4)(+)-N) to nitrite-nitrogen (NO(2)(-)-N) and nitrate-nitrogen (NO(3)(-)-N). The adequacy of modeling NH(4)(+)-N to NO(3)(-)-N oxidation as one composite biochemical reaction was examined at different relative dynamics of NH(4)(+)-N to NO(2)(-)-N and NO(2)(-)-N to NO(3)(-)-N oxidation. NH(4)(+)-N to NO(2)(-)-N oxidation and NO(2)(-)-N to NO(3)(-)-N oxidation by a mixed nitrifying consortium were uncoupled using selective inhibitors allylthiourea and sodium azide. The kinetic parameters of NH(4)(+)-N to NO(2)(-)-N oxidation (q(max,ns) and K(S,ns)) and NO(2)(-)-N to NO(3)(-)-N oxidation (q(max,nb) and K(S,nb)) were determined by a rapid extant respirometric technique. The stoichiometric coefficients relating nitrogen removal, oxygen uptake and biomass synthesis were derived from an electron balanced equation. NH(4)(+)-N to NO(2)(-)-N oxidation was not affected by NO(2)(-)-N concentrations up to 100 mg NO(2)(-)-N L(-1). NO(2)(-)-N to NO(3)(-)-N oxidation was noncompetitively inhibited by NH(4)(+)-N but was not inhibited by NO(3)(-)-N concentrations up to 250 mg NO(3)(-)-N L(-1). When NH(4)(+)-N to NO(2)(-)-N oxidation was the sole rate-limiting step, complete NH(4)(+)-N to NO(3)(-)-N oxidation was adequately modeled as one composite process. However, when NH(4)(+)-N to NO(2)(-)-N oxidation and NO(2)(-)-N to NO(3)(-)-N oxidation were both rate limiting, the estimated lumped kinetic parameter estimates describing NH(4)(+)-N to NO(3)(-)-N oxidation were unrealistically high and correlated. These findings indicate that the use of single-step models to describe batch NH(4)(+) oxidation yields erroneous kinetic parameters when NH(4)(+)-to-NO(2)(-) oxidation is not the sole rate-limiting process throughout the assay. Under such circumstances, it is necessary to quantify NH(4)(+)-N to NO(2)(-)-N oxidation and NO(2)(-)-N to NO(3)(-)-N oxidation, independently.
Collapse
Affiliation(s)
- K Chandran
- Environmental Engineering Program, University of Connecticut, Storrs, Connecticut 06269, USA
| | | |
Collapse
|
23
|
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*b,min from steady-state performance information. Values of S*b,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*b,min, can be used to aid in the design of aerobic FBBRs treating waters containing DNT mixtures.
Collapse
Affiliation(s)
- B F Smets
- Environmental Engineering Program, University of Connecticut, 261 Glenbrook Road, U-37, Storrs, Connecticut 06269-2037, USA.
| | | | | | | |
Collapse
|
24
|
Accashian JV, Vinopal RT, Kim BJ, Smets BF. Aerobic growth on nitroglycerin as the sole carbon, nitrogen, and energy source by a mixed bacterial culture. Appl Environ Microbiol 1998; 64:3300-4. [PMID: 9726874 PMCID: PMC106724 DOI: 10.1128/aem.64.9.3300-3304.1998] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nitroglycerin (glycerol trinitrate [GTN]), an explosive and vasodilatory compound, was metabolized by mixed microbial cultures from aeration tank sludge previously exposed to GTN. Aerobic enrichment cultures removed GTN rapidly in the absence of a supplemental carbon source. Complete denitration of GTN, provided as the sole C and N source, was observed in aerobic batch cultures and proceeded stepwise via the dinitrate and mononitrate isomers, with successive steps occurring at lower rates. The denitration of all glycerol nitrate esters was found to be concomitant, and 1, 2-glycerol dinitrate (1,2-GDN) and 2-glycerol mononitrate (2-GMN) were the primary GDN and GMN isomers observed. Denitration of GTN resulted in release of primarily nitrite-N, indicating a reductive denitration mechanism. Biomass growth at the expense of GTN was verified by optical density and plate count measurements. The kinetics of GTN biotransformation were 10-fold faster than reported for complete GTN denitration under anaerobic conditions. A maximum specific growth rate of 0.048 +/- 0.005 h-1 (mean +/- standard deviation) was estimated for the mixed culture at 25 degreesC. Evidence of GTN toxicity was observed at GTN concentrations above 0. 3 mM. To our knowledge, this is the first report of complete denitration of GTN used as a primary growth substrate by a bacterial culture under aerobic conditions.
Collapse
Affiliation(s)
- J V Accashian
- Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut 06269-2037, USA
| | | | | | | |
Collapse
|
25
|
Abstract
Currently, no fast and accurate methods exist for measuring extant biokinetic parameters for biofilm systems. This article presents a new approach to measure extant biokinetic parameters of biofilms and examines the numerical feasibility of such a method. A completely mixed attached growth bioreactor is subjected to a pulse of substrate, and oxygen consumption is monitored by on-line measurement of dissolved oxygen concentration in the bulk liquid. The oxygen concentration profile is then fit with a mechanistic mathematical model for the biofilm to estimate biokinetic parameters. In this study a transient biofilm model is developed and solved to generate dissolved oxygen profiles in the bulk liquid. Sensitivity analysis of the model reveals that the dissolved oxygen profiles are sufficiently sensitive to the biokinetic parameters-the maximum specific growth rate coefficient (insertion markμ) and the half-saturation coefficient (Ks)-to support parameter estimation if accurate estimates of other model parameters can be obtained. Monte Carlo simulations are conducted with the model to add typical measurement error to the generated dissolved oxygen profiles. Even with measurement error in the dissolved oxygen profile, a pair of biokinetic parameters is always retrievable. The geometric mean of the parameter estimates from the Monte Carlo simulations prove to be an accurate estimator for the true biokinetic values. Higher precision is obtained for insertion markμ estimates than for Ks estimates. In summary, this theoretical analysis reveals that an on-line respirometric assay holds promise for measuring extant biofilm kinetic parameters. Copyright 1998 John Wiley & Sons, Inc.
Collapse
Affiliation(s)
- RG Riefler
- Environmental Engineering Program, University of Connecticut, 261 Glenbrook Road, U-37, Storrs, Connecticut 06269-2037, USA
| | | | | |
Collapse
|
26
|
Smets BF, Jobbágy A, Cowan RM, Grady CP. Evaluation of respirometric data: identification of features that preclude data fitting with existing kinetic expressions. Ecotoxicol Environ Saf 1996; 33:88-99. [PMID: 8744928 DOI: 10.1006/eesa.1996.0010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The use of respirometric for from the evaluation of intrinsic biodegradation kinetic parameters for single organic compounds is discussed. Emphasis is placed on the preliminary assessment of the data set to determine whether it is suitable for kinetic parameter estimation. Careful preliminary examination of the data avoids attempting parameter estimation with unacceptable data. Furthermore, the use of unbiased respirometric data helps ensure that the estimated parameters truly reflect the intrinsic kinetics for biodegradation of a single substrate by the culture tested. Both experimental and theoretical oxygen uptake curves are used to illustrate how various conditions can limit the utility of a given data set. The effect of substrate inhibition, dual or multiple substrate limited growth, inaccuracies in the initial conditions assumed for curve fitting, and the use of poorly acclimated cultures are discussed. Techniques are presented which allow identification of whether a data set is unsuitable and should not be used for parameter estimation. In addition, experimental procedures which can help avoid the collection of aberrant data are discussed.
Collapse
Affiliation(s)
- B F Smets
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs 06269-2037, USA
| | | | | | | |
Collapse
|
27
|
Smets BF, Rittmann BE, Stahl DA. Quantification of the effect of substrate concentration on the conjugal transfer rate of the TOL plasmid in short-term batch mating experiments. Lett Appl Microbiol 1995; 21:167-72. [PMID: 7576502 DOI: 10.1111/j.1472-765x.1995.tb01033.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Batch mating experiments with Pseudomonas putida PAW 1 (TOL) as a donor and Pseudomonas aeruginosa PAO 1162 as a recipient strain were performed to quantify the effect of the substrate concentration in the mating medium on the observed plasmid transfer rate coefficient. The impact of the substrate concentration in the mating medium was highly correlated with the growth history of the donor strain. When the donor strain was harvested in exponential growth phase, no impact was observed; when the donor strain was taken from the stationary phase, however, a strong impact of the substrate concentration was measured: a 10-fold reduction in the substrate concentration decreased the observed plasmid transfer rate by 55%.
Collapse
Affiliation(s)
- B F Smets
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs 06269-2037, USA
| | | | | |
Collapse
|
28
|
Abstract
The kinetics of plasmid conjugation for the TOL and RP4 plasmids depend strongly on the donor cells' specific growth rate and substrate concentration, both of which determine the cells' energy availability. Although transfer rates can be large when energy availability is high, normal biological processes have low energy availability. Therefore, we propose and evaluate preliminarily a simple scheme to create a small zone of high energy availability.
Collapse
Affiliation(s)
- B E Rittmann
- Environmental Engineering Program, Northwestern University, Evanston, Illinois 60208, USA
| | | | | | | |
Collapse
|
29
|
Smets BF, Rittmann BE, Stahl DA. The specific growth rate of Pseudomonas putida PAW1 influences the conjugal transfer rate of the TOL plasmid. Appl Environ Microbiol 1993; 59:3430-7. [PMID: 8250565 PMCID: PMC182470 DOI: 10.1128/aem.59.10.3430-3437.1993] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The kinetics of the conjugal transfer of a TOL plasmid were investigated by using Pseudomonas putida PAW1 as the donor strain and P. aeruginosa PAO 1162 as the recipient strain. Short-term batch mating experiments were performed in a nonselective medium, while the evolution of the different cell types was determined by selective plating techniques. The experimental data were analyzed by using a mass action model that describes plasmid transfer kinetics. This method allowed analysis of the mating experiments by a single intrinsic kinetic parameter for conjugal plasmid transfer. Further results indicated that the specific growth rate of the donor strain antecedent to the mating experiment had a strong impact on the measured intrinsic plasmid transfer rate coefficient, which ranged from 1 x 10(-14) to 5 x 10(-13) ml per cell per min. Preliminary analysis suggested that the transfer rates of the TOL plasmid are large enough to maintain the TOL plasmid in a dense microbial community without selective pressures.
Collapse
Affiliation(s)
- B F Smets
- Department of Civil Engineering, University of Illinois, Urbana 61801
| | | | | |
Collapse
|