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Silva CD, Gómez J, Houbron E, Cuervo-López FM, Texier AC. p-Cresol biotransformation by a nitrifying consortium. Chemosphere 2009; 75:1387-1391. [PMID: 19342073 DOI: 10.1016/j.chemosphere.2009.02.059] [Citation(s) in RCA: 12] [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] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Revised: 02/24/2009] [Accepted: 02/25/2009] [Indexed: 05/27/2023]
Abstract
The oxidizing ability of a nitrifying consortium exposed to p-cresol (25 mg CL(-1)) was evaluated in batch cultures. Biotransformation of the phenolic compound was investigated by identifying the different intermediates formed. p-Cresol inhibited the ammonia-oxidizing process with a decrease of 83% in the specific rate of ammonium consumption. After 48 h, ammonium consumption efficiency was 96+/-9% while nitrate yield reached 0.95+/-0.06 g NO(3)(-)-Ng(-1)NH(4)(+)-N consumed. High value for nitrate production yield showed that the nitrifying metabolic pathway was only affected at the specific rate level being nitrate the main end product. The consortium was able to totally oxidize p-cresol at a specific rate of 0.17+/-0.06 mg p-cresol-Cmg(-1) microbial protein h(-1). p-Cresol was first transformed to p-hydroxybenzaldehyde and p-hydroxybenzoate, which were later completely mineralized. In the presence of allylthiourea, a specific inhibitor of ammonia monooxygenase (AMO), p-cresol was oxidized to the same intermediates and in a similar pattern as obtained without the AMO inhibitor. AMO seemed not to be involved in the p-cresol oxidation process. When p-hydroxybenzaldehyde was added (25 mg CL(-1)), the nitrifying process was inhibited in the same way as observed with p-cresol, indicating that p-hydroxybenzaldehyde could be the main compound responsible for nitrification inhibition. p-Hydroxybenzaldehyde was accumulated during 15 h before complete consumption at a specific rate value eight times lower than the p-cresol consumption rate. Results showed that p-hydroxybenzaldehyde oxidation was the limiting step in p-cresol mineralization by the nitrifying consortium.
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Affiliation(s)
- C D Silva
- Department of Biotechnology-CBS, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco, No. 186-Col, Vicentina DF, Mexico
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Cadena A, Texier AC, González I, Cervantes FJ, Gómez J. Qualitative and quantitative determination of a humic model compound in microbial cultures by cyclic voltammetry. Environ Technol 2007; 28:1035-44. [PMID: 17910256 DOI: 10.1080/09593332808618862] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The humic model compound, anthraquinone-2,6-disulfonate (AQDS), was characterized and measured in microbial cultures by cyclic voltammetry (CV). Under the experimental conditions, the formal reduction potential (E(o')) of the couple AQDS/AHQDS was found to be of -0.520 V vs. SCE (standard calomel electrode) at pH value of 7.0. Control experiments showed that there were no interferences of the culture medium or the microbial consortium on the quantitative determination of the quinone. The linear equation E(o') = -0.294 - 0.032 pH was found, showing that the pH used (7.0-7.8) did not affect significantly the AQDS determination by CV and AHQDS was the predominant hydroquinone formed. A calibration curve was obtained by plotting current response versus AQDS concentration with a linear correlation (r = 0.999) from 0.2 to 10 mM of AQDS. This technique was applied in a denitrifying culture to establish kinetic profiles for AHQDS formation coupled to acetate and p-cresol oxidation. CV results showed that organic matter oxidation by the denitrifying sludge was stoichiometrically associated to AQDS reduction into AHQDS-. CV was shown to be a useful tool for monitoring oxidation/reduction processes of quinones occurring in complex microbial media.
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Affiliation(s)
- A Cadena
- Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, C. P. 09340, DF México
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Zepeda A, Texier AC, Gomez J. Batch nitrifying cultures in presence of mixtures of benzene, toluene, and m-xylene. Environ Technol 2007; 28:355-60. [PMID: 17432387 DOI: 10.1080/09593332808618796] [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: 05/14/2023]
Abstract
Benzene, toluene, and m-xylene compounds in individual (5.0 +/- 0.5 mg C l(-1)) and mixed solutions (2.5 +/- 0.2 mg C l(-1) for each one) in nitrifying batch cultures induced a decrease in the specific rates of NH4+ consumption (81 +/- 6%) and NO3- production (39-79%). However, after 24 h, ammonium consumption efficiency and conversion of consumed NH4+ -N into NO3- -N were close to 100% and there was no significant accumulation of nitrite in the medium. After 24 h, no aromatic intermediate was detected in the cultures and 50% of the mixed compounds was converted to acetate. The following order of biotransformation was found: m-xylene > toluene > benzene. Transformation rate of m-xylene was 0.051 +/- 0.005 g C (g protein-N h)(-1) in individual and mixed solutions. When m-xylene was added, benzene was oxidized at a faster rate (0.051 +/- 0.005 g C (g protein-N h)(-1)) whereas toluene at a slower rate (0.012 +/- 0.002 g C (g protein-N h)(-1)).
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Affiliation(s)
- A Zepeda
- Universidad Aut6noma Metropolitana-Iztapalapa, Div. CBS, Depto de Biotecnología, Av. San Rafael Atlixco 186, C.P. 09340, México DF, México
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Texier AC, Gomez J. Simultaneous nitrification and p-cresol oxidation in a nitrifying sequencing batch reactor. Water Res 2007; 41:315-22. [PMID: 17126873 DOI: 10.1016/j.watres.2006.10.017] [Citation(s) in RCA: 9] [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] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 10/12/2006] [Accepted: 10/13/2006] [Indexed: 05/12/2023]
Abstract
The tolerance, kinetic behavior and oxidizing ability of a nitrifying sludge exposed to different initial concentrations of p-cresol (25-150mg/l) were evaluated in a sequencing batch reactor (SBR) fed with 200mg NH(4)(+)-N/ld. The nitrifying SBR operated up to 300mg/ld of p-cresol, achieving simultaneously the complete ammonium oxidation to nitrate and the total consumption of p-cresol and its transitory intermediates from the culture. p-Cresol induced a significant decrease in the values for specific rates of ammonium consumption, showing that the ammonium oxidation pathway was mainly inhibited. After 7 months of operation in SBR, the specific rates of NH(4)(+)-N oxidation, NO(3)(-)-N formation, and total organic carbon consumption were 0.6g NH(4)(+)-N/g microbial protein-Nh, 0.3g NO(3)(-)-N/g microbial protein-Nh, and 0.24g total organic carbon/g microbial protein h, respectively. The microbial growth rate was always low (maximum value of 12.2+/-0.4mg protein-N/ld) and settleability of the sludge was good with sludge volume index values lower than 21ml/g. The oxidation of p-cresol and its intermediates was carried out faster throughout the cycles and nitrification inhibition decreased with the number of cycles.
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Affiliation(s)
- A-C Texier
- Universidad Autónoma Metropolitana-Iztapalapa, Div. CBS, Departamento de Biotecnología, Av. San Rafael Atlixco 186, Col. Vicentina, C.P. 09340, México, DF
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Zepeda A, Texier AC, Razo-Flores E, Gomez J. Kinetic and metabolic study of benzene, toluene and m-xylene in nitrifying batch cultures. Water Res 2006; 40:1643-9. [PMID: 16603220 DOI: 10.1016/j.watres.2006.02.012] [Citation(s) in RCA: 9] [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] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Revised: 01/11/2006] [Accepted: 02/03/2006] [Indexed: 05/08/2023]
Abstract
The effect of benzene, toluene, and m-xylene (BTX) compounds on the nitrifying activity of a sludge produced in steady-state nitrification was evaluated in batch cultures. Benzene and m-xylene at 10 mg C/L decreased ammonium consumption efficiency by 57% and 26%, respectively, whereas toluene did not affect the ammonium oxidation process. The consumed NH4+-N was totally oxidized to NO3- -N. There was no significant effect at 5 mg C/L of each aromatic compound. BTX (5-20mg C/L) induced a significant decrease in the values for specific rates of NH4+ -N consumption (76-99%) and NO3- -N production (45-98%). At 10 mg C/L of BTX compounds, the inhibition order on nitrate production was: benzene > m-xylene > toluene while at 20 mg C/L, the sequence changed to m-xylene > toluene > benzene for both nitrification inhibition and BTX compounds persistence. At 5 mg C/L of BTX compounds, there was no toxic effect on the sludge whereas from 10 to 50 mgC/L, bacteria did not totally recover their nitrifying activity. At a concentration of 5 mg C/L, toluene was first oxidized to benzyl alcohol, which was later oxidized to butyrate while m-xylene was oxidized to acetate and butyrate.
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Affiliation(s)
- A Zepeda
- Universidad Autónoma Metropolitana-Iztapalapa, Div. CBS, Departamento de Biotecnología. Av. San Rafael Atlixco 186, Col. Vicentina, C.P. 09340, México
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Abstract
A physiological study of a nitrifying sludge was carried out in a sequencing batch reactor (SBR). Pseudo steady-state nitrification conditions were obtained with an ammonium removal efficiency of 99% ± 1% and 98% ± 2% conversion of NH4+-N to NO3–-N. The rate of biomass production was negligible (1.3 ± 0.1 mg microbial protein-N·L–1·d–1). The sludge presented good settling properties with sludge volume index values lower than 20 mL·g–1and an exopolymeric protein/carbohydrate ratio of 0.53 ± 0.34. Kinetic results indicated that the nitrifying behavior of the sludge changed with the number of cycles. After 22 cycles, a decrease in the specific rate of NO3–-N production coupled with an increase in the NO2–-N accumulation were observed. These results showed that the activity of the nitrite oxidizing bacteria decreased at a longer operation time. Ammonia oxidizing bacteria were found to exhibit the best stability. After 4 months of operation, the specific rates of NH4+-N consumption and NO3–-N production were 1.72 NH4+-N per microbial protein-N per hour (g·g–1·h–1) and 0.54 NO3–-N per microbial protein-N per hour (g·g–1·h–1), respectively.Key words: nitrification, sequencing batch reactor, kinetics, settleability, exopolymeric substances.
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Affiliation(s)
- A-C Texier
- Universidad Autónoma Metropolitana-Iztapalapa, Div. CBS, Departamento de Biotecnología, Av. San Rafael Atlixco 186, Col. Vicentina, CP 09340, México D.F.
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Abstract
This paper reviews published work on the sorption of rare earth elements by microbial biomass. In a first part, the biosorption capacities and the various experimental conditions performed in batch reactor experiments are compared. Secondly, sorption modelling generally used in biosorption studies are described. Thirdly, the microbial cell wall characteristics of the metallic ion binding sites are considered. From these observations it seems that the important functional groups for metallic ion fixation are the carboxyl and the phosphate moieties. Moreover, the competing effect of various ions like aluminium, iron, glutamate, sulphate etc. is described. Finally, some adsorption results of the rare earth elements in dynamic reactors are presented.
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Affiliation(s)
- Y Andrès
- Ecole des Mines de Nantes, GEPEA, UMR-CNRS 6144, BP 20722, 44 307 Nantes Cedex 3, France
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Abstract
The effect of benzene on the nitrifying activity of a sludge produced in steady-state nitrification was evaluated in batch cultures. Benzene at 10 mg/L inhibited nitrate formation by 53%, whereas at 5 mg/L there was no inhibition. For initial benzene concentrations of 0, 7, and 10 mg/L, the specific rates of NO(3)(-)-N production were 0.545 +/- 0.101, 0.306 +/- 0.024, and 0.141 +/- 0.010 g NO(3)(-)-N/g microbial protein-N.h, respectively. The specific rates of benzene consumption at 7, 12, and 20 mg/L were 0.034 +/- 0.003, 0.050 +/- 0.006, and 0.027 +/- 0.002 g/g microbial protein-N.h, respectively. Up to a concentration of 10 mg/L, benzene was first oxidized to phenol, which was later totally oxidized to acetate. Benzene at higher concentrations (20 and 30 mg/L) was converted to intermediates other than acetate, phenol, or catechol. These results suggest that this type of nitrifying consortium coupled with a denitrification system may have promising applications for complete removal of nitrogen and benzene from wastewaters.
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Affiliation(s)
- A Zepeda
- Departamento de Biotecnología, Div. CBS, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, C.P. 09340, México, DF
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Texier AC, Andrès Y, Faur-Brasquet C, Le Cloirec P. Fixed-bed study for lanthanide (La, Eu, Yb) ions removal from aqueous solutions by immobilized Pseudomonas aeruginosa: experimental data and modelization. Chemosphere 2002; 47:333-342. [PMID: 11996155 DOI: 10.1016/s0045-6535(01)00244-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A fixed-bed study was carried out by using cells of Pseudomonas aeruginosa immobilized in polyacrylamide gel as a biosorbent for the removal of lanthanide (La, Eu, Yb) ions from aqueous solutions. The effects of superficial liquid velocity based on empty column, particle size, influent concentration and bed depth on the lanthanum breakthrough curves were investigated. Immobilized biomass effectively removed lanthanum from a 6 mM solution with a maximum adsorption capacity of 342 micromolg(-1) (+/-10%) corresponding closely to that observed in earlier batch studies with free bacterial cells. The Bohart and Adams sorption model was employed to determine characteristic parameters useful for process design. Results indicated that the immobilized cells of P. aeruginosa enable removal of lanthanum, europium and ytterbium ions from aqueous effluents with significant and similar maximum adsorption capacities. Experiments with a mixed cation solution showed that the sequence of preferential biosorption was Eu3+ > or = Yb3+ > La3+. Around 96+/-4% of the bound lanthanum was desorbed from the column and concentrated by eluting with a 0.1 M EDTA solution. The feasibility of regenerating and reusing the biomass through three adsorption/desorption cycles was suggested. Neural networks were used to model breakthrough curves performed in the dynamic process. The ability of this statistical tool to predict the breakthrough times was discussed.
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Affiliation(s)
- A C Texier
- Ecole des Mines de Nantes, GEPEA, France
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