Methanogenic activity tests by Infrared Tunable Diode Laser Absorption Spectroscopy.
Methanogenic activity (MA) tests are commonly carried out to estimate the capability of anaerobic biomass to treat effluents, to evaluate anaerobic activity in bioreactors or natural ecosystems, or to quantify inhibitory effects on methanogenic activity. These activity tests are usually based on the measurement of the volume of biogas produced by volumetric, pressure increase or gas chromatography (GC) methods. In this study, we present an alternative method for non-invasive measurement of methane produced during activity tests in closed vials, based on Infrared Tunable Diode Laser Absorption Spectroscopy (MA-TDLAS). This new method was tested during model acetoclastic and hydrogenotrophic methanogenic activity tests and was compared to a more traditional method based on gas chromatography. From the results obtained, the CH(4) detection limit of the method was estimated to 60 ppm and the minimum measurable methane production rate was estimated to 1.09(.)10(-3) mg l(-1) h(-1), which is below CH(4) production rate usually reported in both anaerobic reactors and natural ecosystems. Additionally to sensitivity, the method has several potential interests compared to more traditional methods among which short measurements time allowing the measurement of a large number of MA test vials, non-invasive measurements avoiding leakage or external interferences and similar cost to GC based methods. It is concluded that MA-TDLAS is a promising method that could be of interest not only in the field of anaerobic digestion but also, in the field of environmental ecology where CH(4) production rates are usually very low.
Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del IPN (Cinvestav), Av. IPN 2508, San Pedro Zacatenco, 07360, Mexico City, Mexico. martinezkarla@live.com.mx
Karla
K
Martinez-Cruz
Armando
A
Sepulveda-Jauregui
Nayeli
N
Escobar-Orozco
Frederic
F
Thalasso
D000042:Absorption; D019149:Bioreactors / Q000382:microbiology*; D004783:Environmental Microbiology; D054023:Lasers, Semiconductor; D008697:Methane / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods*
D008697:Methane