Denitrification Coupled with Methane Anoxic Oxidation and Microbial Community Involved Identification

Ano: 2011 | Volume: 54 | Número: 1

Autores: Renata Medici Frayne Cuba, Iolanda Cristina Duarte, Nora Katia Saavedra, Maria Bernadete Amâncio Varesche, EUGÊNIO FORESTI

Palavras-chave: denitrification, methylomonas sp, methane oxidation

Resumo Inglês:

In this work, the biological denitrification associated with anoxic oxidation of methane and the microbial diversity
involved were studied. Kinetic tests for nitrate (NO3
-) and nitrite (NO2
-) removal and methane uptake were carried
out in 100 mL batch reactors incubated in a shaker (40 rpm) at 30 oC. Denitrificant/methanotrophic biomass was
taken from a laboratory scale reactor fed with synthetic nitrified substrates (40 mgN L-1 of NO3
- and subsequently
NO2
-) and methane as carbon source. Results obtained from nitrate removal followed a first order reaction,
presenting a kinetic apparent constant (kNO3)) of 0.0577±0.0057d-1. Two notable points of the denitrification rate
(0.12gNO3
--N g-1 AVS d-1 and 0.07gNO3
--N g-1 AVS d-1) were observed in the beginning and on the seventh day of
operation. When nitrite was added as an electron acceptor, denitrification rates were improved, presenting an
apparent kinetic constant (kNO2) of 0.0722±0.0044d-1, a maximum denitrification rate of 0.6gNO2
--N g-1AVS d-1, and
minimum denitrification rate of 0.1gNO2
--N g-1AVS d-1 at the beginning and end of the test, respectively.
Endogenous material supporting denitrification and methane concentration dissolved in the substrate was discarded
from the control experiments in the absence of methane and seed, respectively. Methylomonas sp. was identified in
the reactors fed with nitrate and nitrite as well as uncultured bacterium.