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(continued) one year after application of the sewage sludge when the harvested turf is placed on either land with a high potential for public exposure or a lawn, unless otherwise specified by the permitting authority.
(vii) Public access to land with a high potential for public exposure shall be restricted for one year after application of sewage sludge.
(viii) Public access to land with a low potential for public exposure shall be restricted for 30 days after application of sewage sludge.
(c) Domestic septage. (1) The site restrictions in §503.32(b)(5) shall be met when domestic septage is applied to agricultural land, forest, or a reclamation site; or
(2) The pH of domestic septage applied to agricultural land, forest, or a reclamation site shall be raised to 12 or higher by alkali addition and, without the addition of more alkali, shall remain at 12 or higher for 30 minutes and the site restrictions in §503.32 (b)(5)(i) through (b)(5)(iv) shall be met.
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42571, Aug. 4, 1999]
§ 503.33 Vector attraction reduction.
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(a)(1) One of the vector attraction reduction requirements in §503.33 (b)(1) through (b)(10) shall be met when bulk sewage sludge is applied to agricultural land, forest, a public contact site, or a reclamation site.
(2) One of the vector attraction reduction requirements in §503.33 (b)(1) through (b)(8) shall be met when bulk sewage sludge is applied to a lawn or a home garden.
(3) One of the vector attraction reduction requirements in §503.33 (b)(1) through (b)(8) shall be met when sewage sludge is sold or given away in a bag or other container for application to the land.
(4) One of the vector attraction reduction requirements in §503.33 (b)(1) through (b)(11) shall be met when sewage sludge (other than domestic septage) is placed on an active sewage sludge unit.
(5) One of the vector attraction reduction requirements in §503.33 (b)(9), (b)(10), or (b)(12) shall be met when domestic septage is applied to agricultural land, forest, or a reclamation site and one of the vector attraction reduction requirements in §503.33 (b)(9) through (b)(12) shall be met when domestic septage is placed on an active sewage sludge unit.
(b)(1) The mass of volatile solids in the sewage sludge shall be reduced by a minimum of 38 percent (see calculation procedures in “Environmental Regulations and Technology—Control of Pathogens and Vector Attraction in Sewage Sludge”, EPA–625/R–92/013, 1992, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268).
(2) When the 38 percent volatile solids reduction requirement in §503.33(b)(1) cannot be met for an anaerobically digested sewage sludge, vector attraction reduction can be demonstrated by digesting a portion of the previously digested sewage sludge anaerobically in the laboratory in a bench-scale unit for 40 additional days at a temperature between 30 and 37 degrees Celsius. When at the end of the 40 days, the volatile solids in the sewage sludge at the beginning of that period is reduced by less than 17 percent, vector attraction reduction is achieved.
(3) When the 38 percent volatile solids reduction requirement in §503.33(b)(1) cannot be met for an aerobically digested sewage sludge, vector attraction reduction can be demonstrated by digesting a portion of the previously digested sewage sludge that has a percent solids of two percent or less aerobically in the laboratory in a bench-scale unit for 30 additional days at 20 degrees Celsius. When at the end of the 30 days, the volatile solids in the sewage sludge at the beginning of that period is reduced by less than 15 percent, vector attraction reduction is achieved.
(4) The specific oxygen uptake rate (SOUR) for sewage sludge treated in an aerobic process shall be equal to or less than 1.5 milligrams of oxygen per hour per gram of total solids (dry weight basis) at a temperature of 20 degrees Celsius.
(5) Sewage sludge shall be treated in an aerobic process for 14 days or longer. During that time, the temperature of the sewage sludge shall be higher than 40 degrees Celsius and the average temperature of the sewage sludge shall be higher than 45 degrees Celsius.
(6) The pH of sewage sludge shall be raised to 12 or higher by alkali addition and, without the addition of more alkali, shall remain at 12 or higher for two hours and then at 11.5 or higher for an additional 22 hours.
(7) The percent solids of sewage sludge that does not contain unstabilized solids generated in a primary wastewater treatment process shall be equal to or greater than 75 percent based on the moisture content and total solids prior to mixing with other materials.
(8) The percent solids of sewage sludge that contains unstabilized solids generated in a primary wastewater treatment process shall be equal to or greater than 90 percent based on the moisture content and total solids prior to mixing with other materials.
(9)(i) Sewage sludge shall be injected below the surface of the land.
(ii) No significant amount of the sewage sludge shall be present on the land surface within one hour after the sewage sludge is injected.
(iii) When the sewage sludge that is injected below the surface of the land is Class A with respect to pathogens, the sewage sludge shall be injected below the land surface within eight hours after being discharged from the pathogen treatment process.
(10)(i) Sewage sludge applied to the land surface or placed on an active sewage sludge unit shall be incorporated into the soil within six hours after application to or placement on the land, unless otherwise specified by the permitting authority.
(ii) When sewage sludge that is incorporated into the soil is Class A with respect to pathogens, the sewage sludge shall be applied to or placed on the land within eight hours after being discharged from the pathogen treatment process.
(11) Sewage sludge placed on an active sewage sludge unit shall be covered with soil or other material at the end of each operating day.
(12) The pH of domestic septage shall be raised to 12 or higher by alkali addition and, without the addition of more alkali, shall remain at 12 or higher for 30 minutes.
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42571, Aug. 4, 1999]
Subpart E—Incineration
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§ 503.40 Applicability.
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(a) This subpart applies to a person who fires sewage sludge in a sewage sludge incinerator, to a sewage sludge incinerator, and to sewage sludge fired in a sewage sludge incinerator.
(b) This subpart applies to the exit gas from a sewage sludge incinerator stack.
(c) The management practice in §503.45(a), the frequency of monitoring requirement for total hydrocarbon concentration in §503.46(b) and the recordkeeping requirements for total hydrocarbon concentration in §503.47(c) and (n) do not apply if the following conditions are met:
(1) The exit gas from a sewage sludge incinerator stack is monitored continuously for carbon monoxide.
(2) The monthly average concentration of carbon monoxide in the exit gas from a sewage sludge incinerator stack, corrected for zero percent moisture and to seven percent oxygen, does not exceed 100 parts per million on a volumetric basis.
(3) The person who fires sewage sludge in a sewage sludge incinerator retains the following information for five years:
(i) The carbon monoxide concentrations in the exit gas; and
(ii) A calibration and maintenance log for the instrument used to measure the carbon monoxide concentration.
(4) Class I sludge management facilities, POTWs (as defined in 40 CFR 501.2) with a design flow rate equal to or greater than one million gallons per day, and POTWs that serve a population of 10,000 people or greater submit the monthly average carbon monoxide concentrations in the exit gas to the permitting authority on February 19 of each year.
[58 FR 9387, Feb. 19, 1993, as amended at 59 FR 9099, Feb. 25, 1994]
§ 503.41 Special definitions.
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(a) Air pollution control device is one or more processes used to treat the exit gas from a sewage sludge incinerator stack.
(b) Auxiliary fuel is fuel used to augment the fuel value of sewage sludge. This includes, but is not limited to, natural gas, fuel oil, coal, gas generated during anaerobic digestion of sewage sludge, and municipal solid waste (not to exceed 30 percent of the dry weight of sewage sludge and auxiliary fuel together). Hazardous wastes are not auxiliary fuel.
(c) Average daily concentration is the arithmetic mean of the concentration of a pollutant in milligrams per kilogram of sewage sludge (dry weight basis) in the samples collected and analyzed in a month.
(d) Control efficiency is the mass of a pollutant in the sewage sludge fed to an incinerator minus the mass of that pollutant in the exit gas from the incinerator stack divided by the mass of the pollutant in the sewage sludge fed to the incinerator.
(e) Dispersion factor is the ratio of the increase in the ground level ambient air concentration for a pollutant at or beyond the property line of the site where the sewage sludge incinerator is located to the mass emission rate for the pollutant from the incinerator stack.
(f) Fluidized bed incinerator is an enclosed device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles suspended in the combustion chamber gas.
(g) Hourly average is the arithmetic mean of all measurements, taken during an hour. At least two measurements must be taken during the hour.
(h) Incineration is the combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device.
(i) Incinerator operating combustion temperature is the arithmetic mean of the temperature readings in the hottest zone of the furnace recorded in a day (24 hours) when the temperature is averaged and recorded at least hourly during the hours the incinerator operates in a day.
(j) Monthly average is the arithmetic mean of the hourly averages for the hours a sewage sludge incinerator operates during the month.
(k) Performance test combustion temperature is the arithmetic mean of the average combustion temperature in the hottest zone of the furnace for each of the runs in a performance test.
(l) Risk specific concentration is the allowable increase in the average daily ground level ambient air concentration for a pollutant from the incineration of sewage sludge at or beyond the property line of the site where the sewage sludge incinerator is located.
(m) Sewage sludge feed rate is either the average daily amount of sewage sludge fired in all sewage sludge incinerators within the property line of the site where the sewage sludge incinerators are located for the number of days in a 365 day period that each sewage sludge incinerator operates, or the average daily design capacity for all sewage sludge incinerators within the property line of the site where the sewage sludge incinerators are located.
(n) Sewage sludge incinerator is an enclosed device in which only sewage sludge and auxiliary fuel are fired.
(o) Stack height is the difference between the elevation of the top of a sewage sludge incinerator stack and the elevation of the ground at the base of the stack when the difference is equal to or less than 65 meters. When the difference is greater than 65 meters, stack height is the creditable stack height determined in accordance with 40 CFR 51.100 (ii).
(p) Total hydrocarbons means the organic compounds in the exit gas from a sewage sludge incinerator stack measured using a flame ionization detection instrument referenced to propane.
(q) Wet electrostatic precipitator is an air pollution control device that uses both electrical forces and water to remove pollutants in the exit gas from a sewage sludge incinerator stack.
(r) Wet scrubber is an air pollution control device that uses water to remove pollutants in the exit gas from a sewage sludge incinerator stack.
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42571, Aug. 4, 1999]
§ 503.42 General requirements.
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No person shall fire sewage sludge in a sewage sludge incinerator except in compliance with the requirements in this subpart.
§ 503.43 Pollutant limits.
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(a) Firing of sewage sludge in a sewage sludge incinerator shall not violate the requirements in the National Emission Standard for Beryllium in subpart C of 40 CFR part 61.
(b) Firing of sewage sludge in a sewage sludge incinerator shall not violate the requirements in the National Emission Standard for Mercury in subpart E of 40 CFR part 61.
(c) Pollutant limit—lead. (1) The average daily concentration for lead in sewage sludge fed to a sewage sludge incinerator shall not exceed the concentration calculated using Equation (4).
Where:
C = Average daily concentration of lead in sewage sludge.
NAAQS = National Ambient Air Quality Standard for lead in micrograms per cubic meter.
DF = Dispersion factor in micrograms per cubic meter per gram per second.
CE = Sewage sludge incinerator control efficiency for lead in hundredths.
SF = Sewage sludge feed rate in metric tons per day (dry weight basis).
(2) The dispersion factor (DF) in equation (4) shall be determined from an air dispersion model in accordance with §503.43(e).
(i) When the sewage sludge stack height is 65 meters or less, the actual sewage sludge incinerator stack height shall be used in the air dispersion model to determine the dispersion factor (DF) for equation (4).
(ii) When the sewage sludge incinerator stack height exceeds 65 meters, the creditable stack height shall be determined in accordance with 40 CFR 51.100(ii) and the creditable stack height shall be used in the air dispersion model to determine the dispersion factor (DF) for equation (4).
(3) The control efficiency (CE) for equation (4) shall be determined from a performance test of the sewage sludge incinerator in accordance with §503.43(e).
(d) Pollutant limit—arsenic, cadmium, chromium, and nickel. (1) The average daily concentration for arsenic, cadmium, chromium, and nickel in sewage sludge fed to a sewage sludge incinerator each shall not exceed the concentration calculated using equation (5).
Where:
C = Average daily concentration of arsenic, cadmium, chromium, or nickel in sewage sludge.
CE = Sewage sludge incinerator control efficiency for arsenic, cadmium, chromium, or nickel in hundredths.
DF = Dispersion factor in micrograms per cubic meter per gram per second.
RSC = Risk specific concentration for arsenic, cadmium, chromium, or nickel in micrograms per cubic meter.
SF = Sewage sludge feed rate in metric tons per day (dry weight basis).
(2) The risk specific concentrations for arsenic, cadmium, and nickel used in equation (5) shall be obtained from Table 1 of §503.43.
Table 1 of § 503.43_Risk Specific Concentration for Arsenic,
Cadmium, and Nickel
------------------------------------------------------------------------
Risk specific
concentration
Pollutant (micrograms
per cubic
meter)
------------------------------------------------------------------------
Arsenic.................................................. 0.023
Cadmium.................................................. 0.057
Nickel................................................... 2.0
------------------------------------------------------------------------
(3) The risk specific concentration for chromium used in equation (5) shall be obtained from Table 2 of §503.43 or shall be calculated using equation (6).
Table 2 of § 503.43_Risk Specific Concentration For Chromium
------------------------------------------------------------------------
Risk specific
concentration
Type of Incinerator (micrograms
per cubic
meter)
------------------------------------------------------------------------
Fluidized bed with wet scrubber.......................... 0.65
Fluidized bed with wet scrubber and wet electrostatic 0.23
precipitator............................................
Other types with wet scrubber............................ 0.064
Other types with wet scrubber and wet electrostatic 0.016
precipitator............................................
------------------------------------------------------------------------
Where:
RSC=risk specific concentration for chromium in micrograms per cubic meter used in equation (5).
r=decimal fraction of the hexavalent chromium concentration in the total chromium concentration measured in the exit gas from the sewage sludge incinerator stack in hundredths.
(4) The dispersion factor (DF) in equation (5) shall be determined from an air dispersion model in accordance with §503.43(e).
(i) When the sewage sludge incinerator stack height is equal to or less than 65 meters, the actual sewage sludge incinerator stack height shall be used in the air dispersion model to determine the dispersion factor (DF) for equation (5).
(ii) When the sewage sludge incinerator stack height is greater than 65 meters, the creditable stack height shall be determined in accordance with 40 CFR 51.100(ii) and the creditable stack height shall be used in the air dispersion model to determine the dispersion factor (DF) for equation (5).
(5) The control efficiency (CE) for equation (5) shall be determined from a performance test of the sewage sludge incinerator in accordance with §503.43(e).
(e) Air dispersion modeling and performance testing. (1) The air dispersion model used to determine the dispersion factor in §503.43 (c)(2) and (d)(4) shall be appropriate for the geographical, physical, and population characteristics at the sewage sludge incinerator site. The performance test used to determine the control efficiencies in §503.43 (c)(3) and (d)(5) shall be appropriate for the type of sewage sludge incinerator.
(2) For air dispersion modeling initiated after September 3, 1999, the modeling results shall be submitted to the permitting authority 30 days after completion of the modeling. In addition to the modeling results, the submission shall include a description of the air dispersion model and the values used for the model parameters.
(3) The following procedures, at a minimum, shall apply in conducting performance tests to determine the control efficiencies in §503.43(c)(3) and (d)(5) after September 3, 1999:
(i) The performance test shall be conducted under representative sewage sludge incinerator conditions at the highest expected sewage sludge feed rate within the design capacity of the sewage sludge incinerator.
(ii) The permitting authority shall be notified at least 30 days prior to any performance test so the permitting authority may have the opportunity to observe the test. The notice shall include a test protocol with incinerator operating conditions and a list of test methods to be used.
(iii) Each performance test shall consist of three separate runs using the applicable test method. The control efficiency for a pollutant shall be the arithmetic mean of the control efficiencies for the pollutant from the three runs.
(4) The pollutant limits in §503.43 (c) and (d) of this section shall be submitted to the permitting authority no later than 30 days after completion of the air dispersion modeling and performance test.
(5) Significant changes in geographic or physical characteristics at the incinerator site or in incinerator operating conditions require new air dispersion modeling or performance testing to determine a new dispersion factor or a new control efficiency that will be used to calculate revised pollutant limits.
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42572, Aug. 4, 1999]
§ 503.44 Operational standard—total hydrocarbons.
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(a) The total hydrocarbons concentration in the exit gas from a sewage sludge incinerator shall be corrected for zero percent moisture by multiplying the measured total hydrocarbons concentration by the correction factor calculated using equation (7).
Where:
X=decimal fraction of the percent moisture in the sewage sludge incinerator exit gas in hundredths.
(b) The total hydrocarbons concentration in the exit gas from a sewage sludge incinerator shall be corrected to seven percent oxygen by multiplying the measured total hydrocarbons concentration by the correction factor calculated using equation (8).
Where:
Y=Percent oxygen concentration in the sewage sludge incinerator stack exit gas (dry volume/dry volume).
(c) The monthly average concentration for total hydrocarbons in the exit gas from a sewage sludge incinerator stack, corrected for zero percent moisture using the correction factor from equation (7) and to seven percent oxygen using the correction factor from equation (8), shall not exceed 100 parts per million on a volumetric basis when measured using the instrument required by §503.45(a).
§ 503.45 Management practices.
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(a)(1) An instrument that continuously measures and records the total hydrocarbons concentration in the sewage sludge incinerator stack exit gas shall be installed, calibrated, operated, and maintained for a sewage sludge incinerator.
(2) The total hydrocarbons instrument shall employ a flame ionization detector; shall have a heated sampling line maintained at a temperature of 150 degrees Celsius or higher at all times; and shall be calibrated at least once every 24-hour operating period using propane.
(b) An instrument that continuously measures and records the oxygen concentration in the sewage sludge incinerator stack exit gas shall be installed, calibrated, operated, and maintained for a sewage sludge incinerator.
(c) An instrument that continuously measures and records information used to determine the moisture content in the sewage sludge incinerator stack exit gas shall be installed, calibrated, operated, and maintained for a sewage sludge incinerator.
(d) An instrument that continuously measures and records combustion temperatures shall be installed, calibrated, operated, and maintained for a sewage sludge incinerator.
(e) Operation of a sewage sludge incinerator shall not cause the operating combustion temperature for the sewage sludge incinerator to exceed the performance test combustion temperature by more than 20 percent.
(f) An air pollution control device shall be appropriate for the type of sewage sludge incinerator and the operating parameters for the air pollution control device shall be adequate to indicate proper performance of the air pollution control device. For sewage sludge incinerators subject to the requirements in subpart O of 40 CFR part 60, operation of the air pollution control device shall not violate the requirements for the air pollution control device in subpart O of 40 CFR part 60. For all other sewage sludge incinerators, operation of the air pollution control device shall not cause a significant exceedance of the average value for the air pollution control device operating parameters from the performance test required by §503.43 (c)(3) and (d)(5).
(g) Sewage sludge shall not be fired in a sewage sludge incinerator if it is likely to adversely affect a threatened or endangered species listed under section 4 of the Endangered Species Act or its designated critical habitat.
(h) The instruments required in §503.45(a)–(d) shall be appropriate for the type of sewage sludge incinerator.
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42573, Aug. 4, 1999]
§ 503.46 Frequency of monitoring.
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(a) Sewage sludge. (1) The frequency of monitoring for beryllium shall be as required in subpart C of 40 CFR part 61, and for mercury as required in subpart E of 40 CFR part 61.
(2) The frequency of monitoring for arsenic, cadmium, chromium, lead, and nickel in sewage sludge fed to a sewage sludge incinerator shall be the frequency in Table 1 of §503.46.
Table 1 of § 503.46_Frequency of Monitoring_Incineration
------------------------------------------------------------------------
Amount of sewage sludge \1\ (metric
tons per 365 day period) Frequency
------------------------------------------------------------------------
Greater than zero but less than 290.. Once per year.
Equal to or greater than 290 but less Once per quarter (four times per
than 1,500. year).
Equal to or greater than 1,500 but Once per 60 days (six times per
less than 15,000. year).
Equal to or greater than 15,000...... Once per month (12 times per
year).
------------------------------------------------------------------------
\1\ Amount of sewage sludge fired in a sewage sludge incinerator (dry
weight basis).
(3) After the sewage sludge has been monitored for two years at the frequency in Table 1 of §503.46, the permitting authority may reduce the frequency of monitoring for arsenic, cadmium, chromium, lead, and nickel.
(b) Total hydrocarbons, oxygen concentration, information to determine moisture content, and combustion temperatures. The total hydrocarbons concentration and oxygen concentration in the exit gas from a sewage sludge incinerator stack, the information used to measure moisture content in the exit gas, and the combustion temperatures for the sewage sludge incinerator shall be monitored continuously.
(c) Air pollution control device operating parameters.For sewage sludge incinerators subject to the requirements in subpart O of 40 CFR part 60, the frequency of monitoring for the appropriate air pollution control device operating parameters shall be the frequency of monitoring in subpart O of 40 CFR part 60. For all other sewage sludge incinerators, the appropriate air pollution control device operating parameters shall be at least daily.
(Approved by the Office of Management and Budget under control number 2040–0157)
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42573, Aug. 4, 1999]
§ 503.47 Recordkeeping.
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(a) The person who fires sewage sludge in a sewage sludge incinerator shall develop the information in §503.47(b) through §503.47(n) and shall retain that information for five years.
(b) The concentration of lead, arsenic, cadmium, chromium, and nickel in the sewage sludge fed to the sewage sludge incinerator.
(c) The total hydrocarbons concentrations in the exit gas from the sewage sludge incinerator stack.
(d) Information that indicates the requirements in the National Emission Standard for beryllium in subpart C of 40 CFR part 61 are met.
(e) Information that indicates the requirements in the National Emission Standard for mercury in subpart E of 40 CFR part 61 are met.
(f) The operating combustion temperatures for the sewage sludge incinerator.
(g) Values for the air pollution control device operating parameters.
(h) The oxygen concentration and information used to measure moisture content in the exit gas from the sewage sludge incinerator stack.
(i) The sewage sludge feed rate.
(j) The stack height for the sewage sludge incinerator.
(k) The dispersion factor for the site where the sewage sludge incinerator is located.
(l) The control efficiency for lead, arsenic, cadmium, chromium, and nickel for each sewage sludge incinerator.
(m) The risk specific concentration for chromium calculated using equation (6), if applicable.
(n) A calibration and maintenance log for the instruments used to measure the total hydrocarbons concentration and oxygen concentration in the exit gas from the sewage sludge incinerator stack, the information needed to determine moisture content in the exit gas, and the combustion temperatures.
(Approved by the Office of Management and Budget under control number 2040–0157)
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42573, Aug. 4, 1999]
§ 503.48 Reporting.
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Class I sludge management facilities, POTWs (as defined in 40 CFR 501.2) with a design flow rate equal to or greater than one million gallons per day, and POTWs that serve a population of 10,000 people or greater shall submit the information in §503.47(b) through §503.47(h) to the permitting authority on February 19 of each year.
(Approved by the Office of Management and Budget under control number 2040–0157)
Appendix A to Part 503—Procedure To Determine the Annual Whole Sludge Application Rate for a Sewage Sludge
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Section 503.13(a)(4)(ii) requires that the product of the concentration for each pollutant listed in Table 4 of §503.13 in sewage sludge sold or given away in a bag or other container for application to the land and the annual whole sludge application rate (AWSAR) for the sewage sludge not cause the annual pollutant loading rate for the pollutant in Table 4 of §503.13 to be exceeded. This appendix contains the procedure used to determine the AWSAR for a sewage sludge that does not cause the annual pollutant loading rates in Table 4 of §503.13 to be exceeded.
The relationship between the annual pollutant loading rate (APLR) for a pollutant and the annual whole sludge application rate (AWSAR) for 1a sewage sludge is shown in equation (1).
Where:
APLR=Annual pollutant loading rate in kilograms per hectare per 365 day period.
C=Pollutant concentration in milligrams, per kilogram of total solids (dry weight basis).
AWSAR=Annual whole sludge application rate in metric tons per hectare per 365 day period (dry weight basis).
0.001=A conversion factor.
To determine the AWSAR, equation (1) is rearranged into equation (2):
The procedure used to determine the AWSAR for a sewage sludge is presented below.
Procedure:
1. Analyze a sample of the sewage sludge to determine the concentration for each of the pollutants listed in Table 4 of §503.13 in the sewage sludge.
2. Using the pollutant concentrations from Step 1 and the APLRs from Table 4 of §503.13, calculate an AWSAR for each pollutant using equation (2) above.
3. The AWSAR for the sewage sludge is the lowest AWSAR calculated in Step 2.
Appendix B to Part 503—Pathogen Treatment Processes
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A. Processes To Significantly Reduce Pathogens (PSRP)
1. Aerobic digestion—Sewage sludge is agitated with air or oxygen to maintain aerobic conditions for a specific mean cell residence time at a specific temperature. Values for the mean cell residence time and temperature shall be between 40 days at 20 degrees Celsius and 60 days at 15 degrees Celsius.
2. Air drying—Sewage sludge is dried on sand beds or on paved or unpaved basins. The sewage sludge dries for a minimum of three months. During two of the three months, the ambient average daily temperature is above zero degrees Celsius.
3. Anaerobic digestion—Sewage sludge is treated in the absence of air for a specific mean cell residence time at a specific temperature. Values for the mean cell residence time and temperature shall be between 15 days at 35 to 55 degrees Celsius and 60 days at 20 degrees Celsius.
4. Composting—Using either the within-vessel, static aerated pile, or windrow composting methods, the temperature of the sewage sludge is raised to 40 degrees Celsius or higher and remains at 40 degrees Celsius or higher for five days. For four hours during the five days, the temperature in the compost pile exceeds 55 degrees Celsius.
5. Lime stabilization—Sufficient lime is added to the sewage sludge to raise the pH of the sewage sludge to 12 after two hours of contact.
B. Processes to Further Reduce Pathogens (PFRP)
1. Composting—Using either the within-vessel composting method or the static aerated pile composting method, the temperature of the sewage sludge is maintained at 55 degrees Celsius or higher for three days.
Using the windrow composting method, the temperature of the sewage sludge is maintained at 55 degrees or higher for 15 days or longer. During the period when the compost is maintained at 55 degrees or higher, there shall be a minimum of five turnings of the windrow.
2. Heat drying—Sewage sludge is dried by direct or indirect contact with hot gases to reduce the moisture content of the sewage sludge to 10 percent or lower. Either the temperature of the sewage sludge particles exceeds 80 degrees Celsius or the wet bulb temperature of the gas in contact with the sewage sludge as the sewage sludge leaves the dryer exceeds 80 degrees Celsius.
3. Heat treatment—Liquid sewage sludge is heated to a temperature of 180 degrees Celsius or higher for 30 minutes.
4. Thermophilic aerobic digestion—Liquid sewage sludge is agitated with air or oxygen to maintain aerobic conditions and the mean cell residence time of the sewage sludge is 10 days at 55 to 60 degrees Celsius.
5. Beta ray irradiation—Sewage sludge is irradiated with beta rays from an accelerator at dosages of at least 1.0 megarad at room temperature (ca. 20 degrees Celsius).
(6) Gamma ray irradiation—Sewage sludge is irradiated with gamma rays from certain isotopes, such as 60 Cobalt and 137 Cesium, at dosages of at least 1.0 megarad at room temperature (ca. 20 °Celsius).
7. Pasteurization—The temperature of the sewage sludge is maintained at 70 degrees Celsius or higher for 30 minutes or longer.
[58 FR 9387, Feb. 19, 1993, as amended at 64 FR 42573, Aug. 4, 1999]