§ 271.933. Vector attraction reduction.
(a) Options.
(1) One of the vector attraction reduction requirements in subsection (b)(1)—(10) shall be met when sewage sludge is applied to agriculture land, forest, a public contact site or a reclamation site.
(2) One of the vector attraction reduction requirements in subsection (b)(1)—(8) shall be met when sewage sludge is applied to a lawn or a home garden.
(3) One of the vector attraction reduction requirements in subsection (b)(1)—(8) shall be met when sewage sludge is sold, given away or otherwise distributed, in a bag or other container for application to the land.
(4) One of the vector attraction reduction requirements in subsection (b)(9), (10) or (11) shall be met when residential septage is applied to agricultural land, forest or a reclamation site.
(b) Standards.
(1) The mass of volatile solids in the sewage sludge shall be reduced by a minimum of 38% (see calculation procedures in ‘‘Environmental Regulations and Technology—Control of Pathogens and Vector Attraction in Sewage Sludge,’’ EPA-625/R-92/013, 1992, United States Environmental Protection Agency, Cincinnati, Ohio 45268).
(2) When the 38% volatile solids reduction requirement in paragraph (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 86° and 98°F (or 30° and 37°C). 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%, vector attraction reduction is achieved.
(3) When the 38% volatile solids reduction requirement in paragraph (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 2% or less aerobically in the laboratory in a bench-scale unit for 30 additional days at 68°F (or 20°C). 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%, vector attraction reduction is achieved.
(4) The 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 68°F (or 20°C).
(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 104°F (or 40°C) and the average temperature of the sewage sludge shall be higher than 113°F (or 45°C).
(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 2 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% 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% based on the moisture content and total solids prior to mixing with other materials.
(9) Sewage sludge shall be injected below the surface of the land. No significant amount of the sewage sludge may be present on the land surface within 1 hour after the sewage sludge is injected. 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 8 hours after being discharged from the pathogen treatment process.
(10) Sewage sludge applied to the land surface shall be incorporated into the soil within 6 hours after application to the land. When sewage sludge that is incorporated into the soil is Class A with respect to pathogens, the sewage sludge shall be applied within 8 hours after being discharged from the pathogen treatment process.
(11) The pH of residential 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.
Cross References This section cited in 25 Pa. Code § 271.821 (relating to application for general permit); 25 Pa. Code § 271.911 (relating to special requirements); 25 Pa. Code § 271.916 (relating to operational standards—pathogens and vector attraction reduction); 25 Pa. Code § 271.917 (relating to frequency of monitoring); 25 Pa. Code § 271.918 (relating to recordkeeping); 25 Pa. Code § 271.931 (relating to special definitions); 25 Pa. Code § 271.932 (relating to pathogens); and 25 Pa. Code § 273.513 (relating to sewage sludge).
APPENDIX A
PATHOGEN TREATMENT PROCESSES
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 68°F (or 20°C) and 60 days at 59°F (or 15°C).
2. Air Drying—Sewage sludge is dried on sand beds or on paved or unpaved basins. The sewage sludge dries for a minimum of 3 months. During 2 of the 3 months, the ambient average daily temperature is above 32°F (or 0°C).
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 95° to 131°F (or 35° to 55°C) and 60 days at 68°F (or 20°C).
4. Composting—Using either the within-vessel, static aerated pile, or windrow composting methods, the temperature of the sewage sludge is raised to 104°F (or 40°C) or higher and remains at 104°F (or 40°C) or higher for 5 days. For 4 hours during the 5 days, the temperature in the compost pile exceeds 131°F (or 55°C).
5. Lime Stabilization—Sufficient lime is added to the sewage sludge to raise the pH of the sewage sludge to 12 after 2 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 131°F (or 55°C) or higher for 3 days.
Using the windrow composting method, the temperature of the sewage sludge is maintained at 131°F (or 55°C) or higher for 15 days or longer. During the period when the compost is maintained at 131°F (or 55°C) 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% or lower. Either the temperature of the sewage sludge particles exceeds 176°F (or 80°C) or the wet bulb temperature of the gas in contact with the sewage sludge as the sewage sludge leaves the dryer exceeds 176°F (or 80°C).
3. Heat Treatment—Liquid sewage sludge is heated to a temperature of 356°F (or 180°C) 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 131° to 140°F (or 55° to 60°C).
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. 68°F or 20°C).
6. Gamma Ray Irradiation—Sewage sludge is irradiated with gamma rays from certain isotopes, such as Cobalt 60 and Cesium 137, at room temperature (CA. 68°F or 20°C).
7. Pasteurization—The temperature of the sewage sludge is maintained at 158°F (or 70°C) or higher for 30 minutes or longer.
Source The provisions of this Appendix A adopted January 24, 1997, effective January 25, 1997, 27 Pa.B. 521.
Cross References This appendix cited in 25 Pa. Code § 273.513 (relating to sewage sludge).
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