40 C.F.R. § 98.353
Where:
CH4Gn = Annual mass CH4 generated from the nth anaerobic wastewater treatment process (metric tons).
n = Index for processes at the facility, used in Equation II-7.
w = Index for weekly measurement period.
Floww = Volume of wastewater sent to an anaerobic wastewater treatment process in week w (m3/week), measured as specified in § 98.354(d) .
CODw = Average weekly concentration of chemical oxygen demand of wastewater entering an anaerobic wastewater treatment process (for week w)(kg/m3), measured as specified in § 98.354(b) and (c) .
B0 = Maximum CH4 producing potential of wastewater (kg CH4/kg COD), use the value 0.25.
MCF = CH4 conversion factor, based on relevant values in Table II-1 of this subpart.
0.001 = Conversion factor from kg to metric tons.
Where:
CH4Gn = Annual mass of CH4 generated from the anaerobic wastewater treatment process (metric tons).
n = Index for processes at the facility, used in Equation II-7.
w = Index for weekly measurement period.
Floww = Volume of wastewater sent to an anaerobic wastewater treatment process in week w(m3/week), measured as specified in § 98.354(d) .
BOD5,w = Average weekly concentration of 5-day biochemical oxygen demand of wastewater entering an anaerobic wastewater treatment process for week w(kg/m3), measured as specified in § 98.354(b) and (c) .
B0 = Maximum CH4 producing potential of wastewater (kg CH4/kg BOD5), use the value 0.6.
MCF = CH4 conversion factor, based on relevant values in Table II-1 to this subpart.
0.001 = Conversion factor from kg to metric tons.
Where:
CH4En = Annual mass of CH4 emissions from the wastewater treatment process n from which biogas is not recovered (metric tons).
CH4Gn = Annual mass of CH4 generated from the wastewater treatment process n, as calculated in Equation II-1 or II-2 of this section (metric tons).
Where:
Rn = Annual quantity of CH4 recovered from the nth anaerobic reactor, sludge digester, or lagoon (metric tons CH4/yr)
n = Index for processes at the facility, used in Equation II-7.
M = Total number of measurement periods in a year. Use M = 365 (M = 366 for leap years) for daily averaging of continuous monitoring, as provided in paragraph (c)(1)of this section. Use M = 52 for weekly sampling, as provided in paragraph (c)(2)of this section.
m = Index for measurement period.
Vm = Cumulative volumetric flow for the measurement period in actual cubic feet (acf). If no biogas was recovered during a monitoring period, use zero.
(KMC)m = Moisture correction term for the measurement period, volumetric basis.
= 1 when (V)m and (CCH4)m are measured on a dry basis or if both are measured on a wet basis.
= 1-(fH2O)m when (V)m is measured on a wet basis and (CCH4)m is measured on a dry basis.
= 1/[1-(fH2O)m] when (V)m is measured on a dry basis and (CCH4)m is measured on a wet basis.
(fH2O)m = Average moisture content of biogas during the measurment period, volumetric basis, (cubic feet water per cubic feet biogas).
(CCH4)m = Average CH4 concentration of biogas during the measurement period, (volume %).
0.0423 = Density of CH4 lb/cf at 520 °R or 60 °F and 1 atm.
520 °R = 520 degrees Rankine.
Tm = Average temperature at which flow is measured for the measurement period (°R). If the flow rate meter automatically corrects for temperature to 520° R, replace "520° R/Tm" with "1".
Pm = Average pressure at which flow is measured for the measurement period (atm). If the flow rate meter automatically corrects for pressure to 1 atm, replace "Pm/1" with "1".
0.454/1,000 = Conversion factor (metric ton/lb).
Where:
CH4Ln = Leakage at the anaerobic process n (metric tons CH4).
n = Index for processes at the facility, used in Equation II-7.
Rn = Annual quantity of CH4 recovered from the nth anaerobic reactor, anaerobic lagoon, or anaerobic sludge digester, as calculated in Equation II-4 of this section (metric tons CH4).
CE = CH4 collection efficiency of anaerobic process n, as specified in Table II-2 of this subpart (decimal).
Where:
CH4En = Annual quantity of CH4 emitted from the process n from which biogas is recovered (metric tons).
n = Index for processes at the facility, used in Equation II-7.
CH4Ln = Leakage at the anaerobic process n, as calculated in Equation II-5 of this section (metric tons CH4).
Rn = Annual quantity of CH4 recovered from the nth anaerobic reactor or anaerobic sludge digester, as calculated in Equation II-4 of this section (metric tons CH4).
DE1 = Primary destruction device CH4 destruction efficiency (lesser of manufacturer's specified destruction efficiency and 0.99). If the biogas is transported off-site for destruction, use DE = 1.
fDest_1 = Fraction of hours the primary destruction device was operating calculated as the annual hours when the destruction device was operating divided by the annual operating hours of the biogas recovery system. If the biogas is transported off-site for destruction, use fDest = 1.
DE2 = Back-up destruction device CH4 destruction efficiency (lesser of manufacturer's specified destruction efficiency and 0.99).
fDest_2 = Fraction of hours the back-up destruction device was operating calculated as the annual hours when the destruction device was operating divided by the annual operating hours of the biogas recovery system.
Where:
CH4ET = Annual mass CH4 emitted from all anaerobic processes at the facility (metric tons).
n = Index for processes at the facility.
CH4En = Annual mass of CH4 emissions from process n (metric tons).
j = Total number of processes from which methane is emitted.
40 C.F.R. §98.353