Waste water treatment anaerobic digestion

The category at business/waste/water/anaerobicdigester provides a methodology for calculating the quantity of methane emissions from anaerobic digesters which are combusted at water treatment plants. The methodology is based on measurements of several plant-specific parameters relating to the flow of emissions from the digester, and is sourced from the guidelines associated with the US EPA's mandatory reporting requirements.

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How to use this category

Selecting an emissions scenario

To use this category, simply create a profile item - there are no drill choices.

Specifying activity data

Next, specify the following profile item values:

• volumetricFlow: the measured volumetric flow rate (i.e. volume per time) of emissions from the digester
• CH4Concentration: the measured concentration of CH₄ in the digester emissions (expressed as a whole percentage, i.e. 0-100)
• temperature: the temperature at which flow measurements were made
• pressure: the pressure at which flow measurements were made
• time: the duration for which the facility was in operation

The assumes default values for the density of CH₄ and the destruction efficiency of combustion. Users can override these default values by specifying their own facility-specific values using the following profile item values:

• destructionEfficiency: the fraction of CH₄ destroyed under combustion (a decimal fraction, 0-1; default, 0.99)
• density: density of CH₄ (i.e. mass per volume)

Results and calculation

The quantities returned represent the methane emissions associated with the quantity specified. The following quantities are returned:

• producedCH4: absolute quantity of CH₄ produced by the anaerobic digestion process
• destroyedCH4: absolute quantity of CH₄ destroyed by combustion
• emittedCH4: absolute quantity of CH₄ emitted (i.e. not destroyed)
• CO2e: emitted CH₄ to CO₂e converted using the appropriate global warming potential)