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Subpart II—Industrial Wastewater Treatment

§ 98.350 Definition of source category.

(a) This source category consists of anaerobic processes 

used to treat industrial wastewater and industrial wastewater 

treatment sludge at facilities that perform the operations 

listed in this paragraph.

(1) Pulp and paper manufacturing.

(2) Food processing.

(3) Ethanol production.

(4) Petroleum refining.

(b) An anaerobic process is a procedure in which organic 

matter in wastewater, wastewater treatment sludge, or other 

material is degraded by micro-organisms in the absence of 

oxygen, resulting in the generation of CO2 and CH4. This source 

category consists of the following: anaerobic reactors, 

anaerobic lagoons, anaerobic sludge digesters, and biogas 

destruction devices (for example, burners, boilers, turbines, 

flares, or other devices).

(1) An anaerobic reactor is an enclosed vessel used for 

anaerobic wastewater treatment (e.g., upflow anaerobic sludge 

blanket, fixed film).

(2) An anaerobic sludge digester is an enclosed vessel in 

which wastewater treatment sludge is degraded anaerobically.
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(3) An anaerobic lagoon is a lined or unlined earthen basin 

used for wastewater treatment, in which oxygen is absent 

throughout the depth of the basin, except for a shallow surface 

zone. Anaerobic lagoons are not equipped with surface aerators. 

Anaerobic lagoons are classified as deep (depth more than 2 

meters) or shallow (depth less than 2 meters).

(c) This source category does not include municipal 

wastewater treatment plants or separate treatment of sanitary 

wastewater at industrial sites.

§ 98.351 Reporting threshold.

You must report GHG emissions under this subpart if your 

facility meets all of the conditions under paragraphs (a) or (b) 

of this section:

(a) Petroleum refineries and pulp and paper manufacturing.

(1) The facility is subject to reporting under subpart Y of 

this part (Petroleum Refineries) or subpart AA of this part 

(Pulp and Paper Manufacturing).

(2) The facility meets the requirements of either 

§98.2(a)(1) or (2).

(3) The facility operates an anaerobic process to treat 

industrial wastewater and/or industrial wastewater treatment 

sludge.

(b) Ethanol production and food processing facilities. 
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(1) The facility performs an ethanol production or food 

processing operation, as defined in §98.358 of this subpart.

(2) The facility meets the requirements of §98.2(a)(2).

(3) The facility operates an anaerobic process to treat 

industrial wastewater and/or industrial wastewater treatment 

sludge.

§ 98.352 GHGs to report.

(a) You must report CH4 generation, CH4 emissions, and CH4

recovered from treatment of industrial wastewater at each 

anaerobic lagoon and anaerobic reactor.

(b) You must report CH4 emissions and CH4 recovered from each 

anaerobic sludge digester.

(c) You must report CH4 emissions and CH4 destruction 

resulting from each biogas collection and biogas destruction 

device.

(d) You must report under subpart C of this part (General 

Stationary Fuel Combustion Sources) the emissions of CO2, CH4, 

and N2O from each stationary combustion unit associated with the 

biogas destruction device, if present, by following the 

requirements of subpart C of this part.

§ 98.353 Calculating GHG emissions.

(a) For each anaerobic reactor and anaerobic lagoon, 

estimate the annual mass of CH4 generated according to the 
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applicable requirements in paragraphs (a)(1) through (a)(2) of 

this section.

(1) If you measure the concentration of organic material 

entering the anaerobic reactors or anaerobic lagoon using 

methods for the determination of chemical oxygen demand (COD), 

then estimate annual mass of CH4 generated using Equation II–1 of 

this section.

(Eq. II-1)

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.

(2) If you measure the concentration of organic material 

entering an anaerobic reactor or anaerobic lagoon using methods 
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for the determination of 5-day biochemical oxygen demand (BOD5), 

then estimate annual mass of CH4 generated using Equation II–2 of 

this section.

(Eq. II-2)

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.

(b) For each anaerobic reactor and anaerobic lagoon from 

which biogas is not recovered, estimate annual CH4 emissions 

using Equation II–3 of this section.

(Eq. II-3)2

Where:
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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).

(c) For each anaerobic sludge digester, anaerobic reactor, 

or anaerobic lagoon from which some biogas is recovered, 

estimate the annual mass of CH4 recovered according to the 

requirements in paragraphs (c)(1) and (c)(2) of this section. To 

estimate the annual mass of CH4 recovered, you must continuously 

monitor biogas flow rate and determine the volume of biogas each 

week and the cumulative volume of biogas each year that is 

collected and routed to a destruction device as specified in 

§98.354(h). If the gas flow meter is not equipped with automatic 

correction for temperature, pressure, or, if necessary, moisture 

content, you must determine these parameters as specified in 

paragraph (c)(2)(ii) of this section.

(1) If you continuously monitor CH4 concentration (and if 

necessary, temperature, pressure, and moisture content required 

as specified in §98.354(f)) of the biogas that is collected and 

routed to a destruction device using a monitoring meter 

specifically for CH4 gas, as specified in §98.354(g), you must 

use this monitoring system and calculate the quantity of CH4

recovered for destruction using Equation II–4 of this section. A 

fully integrated system that directly reports CH4 quantity 
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requires only the summing of results of all monitoring periods 

for a given year.

(Eq. II-4)

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 %).
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0.0423 = Density of CH4lb/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).

(2) If you do not continuously monitor CH4 concentration 

according to paragraph (c)(1) of this section, you must 

determine the CH4 concentration, temperature, pressure, and, if 

necessary, moisture content of the biogas that is collected and 

routed to a destruction device according to the requirements in 

paragraphs (c)(2)(i) through (c)(2)(ii) of this section and 

calculate the quantity of CH4 recovered for destruction using 

Equation II–4 of this section.

(i) Determine the CH4 concentration in the biogas that is 

collected and routed to a destruction device in a location near 

or representative of the location of the gas flow meter at least 

once each calendar week; if only one measurement is made each 

calendar week, there must be least three days between 

measurements. For a given calendar week, you are not required to 

determine CH4 concentration if the cumulative volume of biogas 
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for that calendar week, determined as specified in paragraph (c) 

of this section, is zero.

(ii) If the gas flow meter is not equipped with automatic 

correction for temperature, pressure, or, if necessary, moisture 

content:

(A) Determine the temperature and pressure in the biogas 

that is collected and routed to a destruction device in a 

location near or representative of the location of the gas flow 

meter at least once each calendar week; if only one measurement 

is made each calendar week, there must be at least three days 

between measurements.

(B) If the CH4 concentration is determined on a dry basis 

and biogas flow is determined on a wet basis, or CH4

concentration is determined on a wet basis and biogas flow is 

determined on a dry basis, and the flow meter does not 

automatically correct for moisture content, determine the 

moisture content in the biogas that is collected and routed to a 

destruction device in a location near or representative of the 

location of the gas flow meter at least once each calendar week 

that the cumulative biogas flow measured as specified in 

§98.354(h) is greater than zero; if only one measurement is made 

each calendar week, there must be at least three days between 

measurements.
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(d) For each anaerobic sludge digester, anaerobic reactor, 

or anaerobic lagoon from which some quantity of biogas is 

recovered, you must estimate both the annual mass of CH4 that is 

generated, but not recovered, according to paragraph (d)(1) of 

this section and the annual mass of CH4 emitted according to 

paragraph (d)(2) of this section.

(1) Estimate the annual mass of CH4 that is generated, but 

not recovered, using Equation II–5 of this section.

(Eq. II-5)

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).

(2) For each anaerobic sludge digester, anaerobic reactor, 

or anaerobic lagoon from which some quantity of biogas is 

recovered, estimate the annual mass of CH4 emitted using Equation 

II–6 of this section.

(Eq. II-6)
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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.

(e) Estimate the total mass of CH4 emitted from all 

anaerobic processes from which biogas is not recovered 

(calculated in Eq. II–3) and all anaerobic processes from which 
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some biogas is recovered (calculated in Equation II–6) using 

Equation II–7 of this section.

(Eq. II-7)

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.

§ 98.354 Monitoring and QA/QC requirements.

(a) For calendar year 2011 monitoring, the facility may 

submit a request to the Administrator to use one or more best 

available monitoring methods as listed in §98.3(d)(1)(i) through 

(iv). The request must be submitted no later than October 12, 

2010 and must contain the information in §98.3(d)(2)(ii). To 

obtain approval, the request must demonstrate to the 

Administrator's satisfaction that it is not reasonably feasible 

to acquire, install, and operate a required piece of monitoring 

equipment by January 1, 2011. The use of best available 

monitoring methods will not be approved beyond December 31, 

2011.
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(b) You must determine the concentration of organic 

material in wastewater treated anaerobically using analytical 

methods for COD or BOD5 specified in 40 CFR 136.3 Table 1B. For 

the purpose of determining concentrations of wastewater influent 

to the anaerobic wastewater treatment process, samples may be 

diluted to the concentration range of the approved method, but 

the calculated concentration of the undiluted wastewater must be 

used for calculations and reporting required by this subpart.

(c) You must collect samples representing wastewater 

influent to the anaerobic wastewater treatment process, 

following all preliminary and primary treatment steps ( e.g., 

after grit removal, primary clarification, oil-water separation, 

dissolved air flotation, or similar solids and oil separation 

processes). You must collect and analyze samples for COD or BOD5

concentration at least once each calendar week that the 

anaerobic wastewater treatment process is operating; if only one 

measurement is made each calendar week, there must be at least 

three days between measurements. You must collect a sample that 

represents the average COD or BOD5 concentration of the waste 

stream over a 24-hour sampling period. You must collect a 

minimum of four sample aliquots per 24-hour period and composite 

the aliquots for analysis. Collect a flow-proportional composite 

sample (either constant time interval between samples with 

sample volume proportional to stream flow, or constant sample 
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volume with time interval between samples proportional to stream 

flow). Follow sampling procedures and techniques presented in 

Chapter 5, Sampling, of the “NPDES Compliance Inspection 

Manual,” (incorporated by reference, see §98.7) or Section 

7.1.3, Sample Collection Methods, of the “U.S. EPA NPDES Permit 

Writers' Manual,” (incorporated by reference, see §98.7).

(d) You must measure the flowrate of wastewater entering 

anaerobic wastewater treatment process at least once each 

calendar week that the process is operating; if only one 

measurement is made each calendar week, there must be at least 

three days between measurements. You must measure the flowrate 

for the 24-hour period for which you collect samples analyzed 

for COD or BOD5 concentration. The flow measurement location must 

correspond to the location used to collect samples analyzed for 

COD or BOD5 concentration. You must measure the flowrate using 

one of the methods specified in paragraphs (d)(1) through (d)(5) 

of this section or as specified by the manufacturer.

(1) ASME MFC–3M–2004 Measurement of Fluid Flow in Pipes 

Using Orifice, Nozzle, and Venturi (incorporated by reference, 

see §98.7).

(2) ASME MFC–5M–1985 (Reaffirmed 1994) Measurement of 

Liquid Flow in Closed Conduits Using Transit-Time Ultrasonic 

Flowmeters (incorporated by reference, see §98.7).
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(3) ASME MFC–16–2007 Measurement of Liquid Flow in Closed 

Conduits with Electromagnetic Flowmeters (incorporated by 

reference, see §98.7).

(4) ASTM D1941–91 (Reapproved 2007) Standard Test Method 

for Open Channel Flow Measurement of Water with the Parshall 

Flume, approved June 15, 2007, (incorporated by reference, see 

§98.7).

(5) ASTM D5614–94 (Reapproved 2008) Standard Test Method 

for Open Channel Flow Measurement of Water with Broad-Crested 

Weirs, approved October 1, 2008, (incorporated by reference, see 

§98.7).

(e) All wastewater flow measurement devices must be 

calibrated prior to the first year of reporting and recalibrated 

either biennially (every 2 years) or at the minimum frequency 

specified by the manufacturer. Wastewater flow measurement 

devices must be calibrated using the procedures specified by the 

device manufacturer.

(f) For each anaerobic process (such as anaerobic reactor, 

sludge digester, or lagoon) from which biogas is recovered, you 

must make the measurements or determinations specified in 

paragraphs (f)(1) through (f)(3) of this section.

(1) You must continuously measure the biogas flow rate as 

specified in paragraph (h) of this section and determine the 

cumulative volume of biogas recovered.
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(2) You must determine the CH4 concentration of the 

recovered biogas as specified in paragraph (g) of this section 

at a location near or representative of the location of the gas 

flow meter. You must determine CH4 concentration either 

continuously or intermittently. If you determine the 

concentration intermittently, you must determine the 

concentration at least once each calendar week that the 

cumulative biogas flow measured as specified in paragraph (h) of 

this section is greater than zero, with at least three days 

between measurements.

(3) As specified in §98.353(c) and paragraph (h) of this 

section, you must determine temperature, pressure, and moisture 

content as necessary to accurately determine the biogas flow 

rate and CH4 concentration. You must determine temperature and 

pressure if the gas flow meter or gas composition monitor do not 

automatically correct for temperature or pressure. You must 

measure moisture content of the recovered biogas if the biogas 

flow rate is measured on a wet basis and the CH4 concentration is 

measured on a dry basis. You must also measure the moisture 

content of the recovered biogas if the biogas flow rate is 

measured on a dry basis and the CH4 concentration is measured on 

a wet basis.

(g) For each anaerobic process (such as an anaerobic 

reactor, sludge digester, or lagoon) from which biogas is 
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recovered, operate, maintain, and calibrate a gas composition 

monitor capable of measuring the concentration of CH4 in the 

recovered biogas using one of the methods specified in 

paragraphs (g)(1) through (g)(6) of this section or as specified 

by the manufacturer.

(1) Method 18 at 40 CFR part 60, appendix A–6.

(2) ASTM D1945–03, Standard Test Method for Analysis of 

Natural Gas by Gas Chromatography (incorporated by reference, 

see §98.7).

(3) ASTM D1946–90 (Reapproved 2006), Standard Practice for 

Analysis of Reformed Gas by Gas Chromatography (incorporated by 

reference, see §98.7).

(4) GPA Standard 2261–00, Analysis for Natural Gas and 

Similar Gaseous Mixtures by Gas Chromatography (incorporated by 

reference, see §98.7).

(5) ASTM UOP539–97 Refinery Gas Analysis by Gas 

Chromatography (incorporated by reference, see §98.7).

(6) As an alternative to the gas chromatography methods 

provided in paragraphs (g)(1) through (g)(5) of this section, 

you may use total gaseous organic concentration analyzers and 

calculate the CH4 concentration following the requirements in 

paragraphs (g)(6)(i) through (g)(6)(iii) of this section.

(i) Use Method 25A or 25B at 40 CFR part 60, appendix A–7 

to determine total gaseous organic concentration. You must 
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calibrate the instrument with CH4 and determine the total gaseous 

organic concentration as carbon (or as CH4; K=1 in Equation 25A–1 

of Method 25A at 40 CFR part 60, appendix A–7).

(ii) Determine a non-methane organic carbon correction 

factor at the routine sampling location no less frequently than 

once a reporting year following the requirements in paragraphs 

(g)(6)(ii)(A) through (g)(6)(ii)(C) of this section.

(A) Take a minimum of three grab samples of the biogas with 

a minimum of 20 minutes between samples and determine the 

methane composition of the biogas using one of the methods 

specified in paragraphs (g)(1) through (g)(5) of this section.

(B) As soon as practical after each grab sample is 

collected and prior to the collection of a subsequent grab 

sample, determine the total gaseous organic concentration of the 

biogas using either Method 25A or 25B at 40 CFR part 60, 

appendix A–7 as specified in paragraph (g)(6)(i) of this 

section.

(C) Determine the arithmetic average methane concentration 

and the arithmetic average total gaseous organic concentration 

of the samples analyzed according to paragraphs (g)(6)(ii)(A) 

and (g)(6)(ii)(B) of this section, respectively, and calculate 

the non-methane organic carbon correction factor as the ratio of 

the average methane concentration to the average total gaseous 
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organic concentration. If the ratio exceeds 1, use 1 for the 

non-methane organic carbon correction factor.

(iii) Calculate the CH4 concentration as specified in 

Equation II–8 of this section.

(Eq. II-8)

Where:

CCH4 = Methane (CH4) concentration in the biogas 

(volume %) for use in Equation II–4 of this 

subpart.

fNMOC = Non-methane organic carbon correction factor 

from the most recent determination of the nonmethane organic carbon correction factor as 

specified in paragraph (g)(6)(ii) of this 

section (unitless).

CTGOC = Total gaseous organic carbon concentration 

measured using Method 25A or 25B at 40 CFR 

part 60, appendix A–7 during routine 

monitoring of the biogas (volume %).

(h) For each anaerobic process (such as an anaerobic 

reactor, sludge digester, or lagoon) from which biogas is 

recovered, install, operate, maintain, and calibrate a gas flow 

meter capable of continuously measuring the volumetric flow rate 

of the recovered biogas using one of the methods specified in 

paragraphs (h)(1) through (h)(8) of this section or as specified 

by the manufacturer. Recalibrate each gas flow meter either 

biennially (every 2 years) or at the minimum frequency specified 

by the manufacturer. Except as provided in §98.353(c)(2)(iii), 
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each gas flow meter must be capable of correcting for the 

temperature and pressure and, if necessary, moisture content.

(1) ASME MFC–3M–2004, Measurement of Fluid Flow in Pipes 

Using Orifice, Nozzle, and Venturi (incorporated by reference, 

see §98.7).

(2) ASME MFC–4M–1986 (Reaffirmed 1997), Measurement of Gas 

Flow by Turbine Meters (incorporated by reference, see §98.7).

(3) ASME MFC–6M–1998, Measurement of Fluid Flow in Pipes 

Using Vortex Flowmeters (incorporated by reference, see §98.7).

(4) ASME MFC–7M–1987 (Reaffirmed 1992), Measurement of Gas 

Flow by Means of Critical Flow Venturi Nozzles (incorporated by 

reference, see §98.7).

(5) ASME MFC–11M–2006 Measurement of Fluid Flow by Means of 

Coriolis Mass Flowmeters (incorporated by reference, see §98.7). 

The mass flow must be corrected to volumetric flow based on the 

measured temperature, pressure, and biogas composition.

(6) ASME MFC–14M–2003 Measurement of Fluid Flow Using Small 

Bore Precision Orifice Meters (incorporated by reference, see 

§98.7).

(7) ASME MFC–18M–2001 Measurement of Fluid Flow using 

Variable Area Meters (incorporated by reference, see §98.7).

(8) Method 2A or 2D at 40 CFR part 60, appendix A–1.

(i) All temperature, pressure, and, moisture content 

monitors required as specified in paragraph (f) of this section 
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must be calibrated using the procedures and frequencies where 

specified by the device manufacturer, if not specified use an 

industry accepted or industry standard practice.

(j) All equipment (temperature, pressure, and moisture 

content monitors and gas flow meters and gas composition 

monitors) must be maintained as specified by the manufacturer.

(k) If applicable, the owner or operator must document the 

procedures used to ensure the accuracy of measurements of COD or 

BOD5 concentration, wastewater flow rate, biogas flow rate, 

biogas composition, temperature, pressure, and moisture content. 

These procedures include, but are not limited to, calibration of 

gas flow meters, and other measurement devices. The estimated 

accuracy of measurements made with these devices must also be 

recorded, and the technical basis for these estimates must be 

documented.

§ 98.355 Procedures for estimating missing data.

A complete record of all measured parameters used in the 

GHG emissions calculations is required. Therefore, whenever a 

quality-assured value of a required parameter is unavailable 

(e.g., if a meter malfunctions during unit operation or if a 

required sample is not taken), a substitute data value for the 

missing parameter must be used in the calculations, according to 

the following requirements in paragraphs (a) through (c) of this 

section:
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(a) For each missing weekly value of COD or BOD5 or 

wastewater flow entering an anaerobic wastewater treatment 

process, the substitute data value must be the arithmetic 

average of the quality-assured values of those parameters for 

the week immediately preceding and the week immediately 

following the missing data incident.

(b) For each missing value of the CH4 content or biogas flow 

rates, the substitute data value must be the arithmetic average 

of the quality-assured values of that parameter immediately 

preceding and immediately following the missing data incident.

(c) If, for a particular parameter, no quality-assured data 

are available prior to the missing data incident, the substitute 

data value must be the first quality-assured value obtained 

after the missing data period. If, for a particular parameter, 

the “after” value is not obtained by the end of the reporting 

year, you may use the last quality-assured value obtained 

“before” the missing data period for the missing data 

substitution. You must document and keep records of the 

procedures you use for all such estimates.

§ 98.356 Data reporting requirements.

In addition to the information required by §98.3(c), each 

annual report must contain the following information for each 

wastewater treatment system.
Page 23 of 28

(a) A description or diagram of the industrial wastewater 

treatment system, identifying the processes used to treat 

industrial wastewater and industrial wastewater treatment 

sludge. Indicate how the processes are related to each other and 

identify the anaerobic processes. Provide a unique identifier 

for each anaerobic process, indicate the average depth in meters 

of each anaerobic lagoon, and indicate whether biogas generated 

by each anaerobic process is recovered. The anaerobic processes 

must be identified as:

(1) Anaerobic reactor.

(2) Anaerobic deep lagoon (depth more than 2 meters).

(3) Anaerobic shallow lagoon (depth less than 2 meters).

(4) Anaerobic sludge digester.

(b) For each anaerobic wastewater treatment process 

(reactor, deep lagoon, or shallow lagoon) you must report:

(1) Weekly average COD or BOD5 concentration of wastewater 

entering each anaerobic wastewater treatment process, for each 

week the anaerobic process was operated.

(2) Volume of wastewater entering each anaerobic wastewater 

treatment process for each week the anaerobic process was 

operated.

(3) Maximum CH4 production potential (B0) used as an input 

to Equation II–1 or II–2 of this subpart, from Table II–1 to 

this subpart.
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(4) Methane conversion factor (MCF) used as an input to 

Equation II–1 or II–2 of this subpart, from Table II–1 to this 

subpart.

(5) Annual mass of CH4 generated by each anaerobic 

wastewater treatment process, calculated using Equation II–1 or 

II–2 of this subpart.

(c) For each anaerobic wastewater treatment process from 

which biogas is not recovered, you must report the annual CH4

emissions, calculated using Equation II–3 of this subpart.

(d) For each anaerobic wastewater treatment process and 

anaerobic sludge digester from which some biogas is recovered, 

you must report:

(1) Annual quantity of CH4 recovered from the anaerobic 

process calculated using Equation II–4 of this subpart.

(2) Total weekly volumetric biogas flow for each week (up 

to 52 weeks/year) that biogas is collected for destruction.

(3) Weekly average CH4 concentration for each week that 

biogas is collected for destruction.

(4) Weekly average biogas temperature for each week at 

which flow is measured for biogas collected for destruction, or 

statement that temperature is incorporated into monitoring 

equipment internal calculations.

(5) Whether flow was measured on a wet or dry basis, 

whether CH4 concentration was measured on a wet or dry basis, and 
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if required for Equation II–4 of this subpart, weekly average 

moisture content for each week at which flow is measured for 

biogas collected for destruction, or statement that moisture 

content is incorporated into monitoring equipment internal 

calculations.

(6) Weekly average biogas pressure for each week at which 

flow is measured for biogas collected for destruction, or 

statement that pressure is incorporated into monitoring 

equipment internal calculations.

(7) CH4 collection efficiency (CE) used in Equation II–5 of 

this subpart.

(8) Whether destruction occurs at the facility or off-site. 

If destruction occurs at the facility, also report whether a 

back-up destruction device is present at the facility, the 

annual operating hours for the primary destruction device, the

annual operating hours for the back-up destruction device (if 

present), the destruction efficiency for the primary destruction 

device, and the destruction efficiency for the back-up 

destruction device (if present).

(9) For each anaerobic process from which some biogas is 

recovered, you must report the annual CH4 emissions, as 

calculated by Equation II–6 of this subpart.

(e) The total mass of CH4 emitted from all anaerobic 

processes from which biogas is not recovered (calculated in 
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Equation II–3 of this subpart) and from all anaerobic processes 

from which some biogas is recovered (calculated in Equation II–6 

of this subpart) using Equation II–7 of this subpart.

§ 98.357 Records that must be retained.

In addition to the information required by §98.3(g), you 

must retain the calibration records for all monitoring 

equipment, including the method or manufacturer's specification 

used for calibration.

§ 98.358 Definitions.

Except as provided below, all terms used in this subpart 

have the same meaning given in the CAA and subpart A of this 

part.

Biogas means the combination of CO2, CH4, and other gases 

produced by the biological breakdown of organic matter in the 

absence of oxygen.

Ethanol production means an operation that produces ethanol 

from the fermentation of sugar, starch, grain, or cellulosic 

biomass feedstocks, or the production of ethanol synthetically 

from petrochemical feedstocks, such as ethylene or other 

chemicals.

Food processing means an operation used to manufacture or 

process meat, poultry, fruits, and/or vegetables as defined 

under NAICS 3116 (Meat Product Manufacturing) or NAICS 3114 

(Fruit and Vegetable Preserving and Specialty Food 
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Manufacturing). For information on NAICS codes, see 

http://www.census.gov/eos/www/naics/ .

Industrial wastewater means water containing wastes from an 

industrial process. Industrial wastewater includes water which 

comes into direct contact with or results from the storage, 

production, or use of any raw material, intermediate product, 

finished product, by-product, or waste product. Examples of 

industrial wastewater include, but are not limited to, paper 

mill white water, wastewater from equipment cleaning, wastewater 

from air pollution control devices, rinse water, contaminated 

stormwater, and contaminated cooling water.

Industrial wastewater treatment sludge means solid or semisolid material resulting from the treatment of industrial 

wastewater, including but not limited to biosolids, screenings, 

grit, scum, and settled solids.

Wastewater treatment system means the collection of all 

processes that treat or remove pollutants and contaminants, such 

as soluble organic matter, suspended solids, pathogenic 

organisms, and chemicals from wastewater prior to its reuse or 

discharge from the facility.

Table II–1 to Subpart II—Emission Factors

Factors

Default 

value Units

B0—for facilities monitoring COD 0.25 Kg CH4/kg COD

B0—for facilities monitoring BOD5 0.60 Kg CH4/kg 
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Table II–1 to Subpart II—Emission Factors

Factors

Default 

value Units

BOD5

MCF—anaerobic reactor 0.8 Fraction.

MCF—anaerobic deep lagoon (depth more than 2 

m)

0.8 Fraction.

MCF—anaerobic shallow lagoon (depth less than 

2 m)

0.2 Fraction.

Table II–2 to Subpart II—Collection Efficiencies of Anaerobic 

Processes

Anaerobic process type Cover type

Methane collection 

efficiency

Covered anaerobic lagoon 

(biogas capture)

Bank to bank, 

impermeable

0.975

Modular, 

impermeable

0.70

Anaerobic sludge digester; 

anaerobic reactor

Enclosed Vessel 0.99