Methanogenesis AND ANAEROBIC DIGESTION

Control and monitoring of methanogenesis and anaerobic digestion process through 2nd generation ATP-metry

Methane production process

Methanogenesis is a biological phenomenon of anaerobic digestion of organic matter. Through several biochemical steps (hydrolysis, acidogenesis, acetogenesis, methanogenesis), organic matter is converted into biogas, mainly made up of carbon dioxide and methane. A lot of bacteria species take part in methanogenesis process.

The three main goals of methanogenesis are:

1. Energetic valorization by producing and recovering methane

2. Reduce of organic wastes

3. Nutrients-rich digestate production used as soil amendment

Application of QG21W™ test kit for control, monitoring and optimization of methane production

Anaerobic digesters number is quickly increasing but biogas production yield is not always a well monitored parameter. Thus, determining and analysing parameters impacting process yield is the subject of many scientific studies.

Methanogenesis is a delicate process. Thus, anaerobic microorganisms can be disrupted by sudden variations of temperature, pH, organic matter, by a too high molecular oxygen concentration, etc. Anaerobic microorganisms are the first species disrupted by a toxic component arrival in influents.

Monitoring a biological process should be based on biological parameters. Using 2nd generation ATP-metry makes possible the quantification of total living flora in samples taken of reactors in only few minutes. Quench-Gone21™ Wastewater test kit (QG21W) measures concentration of microorganisms through the quantification of intracellular ATP in samples. Intracellular ATP is an indicator of active biomass. All living cells contain ATP, aerobic or anaerobic bacteria, molds, yeasts, amoeba, etc.

QG21W test kit allows determining Biomass Stress Index (BSI™), representing the living biomass population stress and health.

Detection and study of toxic influents

Massive arrival of toxic influent or an important variation of the influents quality is likely to disrupt methanogenesis process. Anaerobic bacteria can be disrupted by any variation from influents composition. Currently, due to the lack of suitable biological tools, these accidents are generally regarded as inevitable.

QG21W test kit allows a precise and easy surveillance of influent stress and, thus, of organic matter toxicity. The Biomass Stress Index (BSI) is the parameter obtained using the QG21W test kit and expressing the ratio of dead biomass to total biomass. The higher the BSI index, the higher the mortality of microorganisms. The technology enables distinguishing between toxicity linked to an influent or toxicity linked to digester operating conditions (nutrient disorder, brutal changes of temperature, pH). If a toxic influent is responsible for disturbing health of active biomass, simple to implement jar-test studies can be conducted for identifying the individual influent or the toxic product responsible for the toxicity. The method also makes possible determining the maximum concentration of the toxic element which can enter the digester without disturbing active biomass. Using QG21 Wastewater to realize toxicity studies allows quickly identify influent responsible for problems.

Help for process monitoring

Methane potential measurement, called BMP (Biochemical Methane Potential) is the most commonly used parameter to determine the theoretical methane production from a substrate. This parameter is used for process optimization and for feasibility study of installations.

ATP-metry is used as a complementary indicator to monitor digesters. Using QG21W test kit, quantification of microorganisms is now possible in only 3 minutes. Furthermore, health biomass can now be controlled. Combined with BMP measurement, ATP-metry allows foretelling biomass response into a digester. Thus, QG21W test kit can be used for digester organic matter loading and for reactor monitoring and optimization.