Kinetic and metabolic study of benzene, toluene and m-xylene in nitrifying batch cultures.
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.
Zepeda
A
A
Universidad Autónoma Metropolitana-Iztapalapa, Div. CBS, Departamento de Biotecnología. Av. San Rafael Atlixco 186, Col. Vicentina, C.P. 09340, México.
Texier
A-C
AC
Razo-Flores
E
E
Gomez
J
J
D001554:Benzene / Q000378:metabolism*; D007700:Kinetics; D009573:Nitrites / Q000378:metabolism*; D014050:Toluene / Q000378:metabolism*; D014992:Xylenes / Q000378:metabolism*
D009573:Nitrites; D014992:Xylenes; D014050:Toluene; D001554:Benzene; C031285:3-xylene