Pa. Code tit. 25, pt. I, subpt. D, art. VIII, ch. 271, subch. J, PATHOGENS AND VECTOR ATTRACTION REDUCTION, app A
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.
Pa. Code tit. 25, pt. I, subpt. D, art. VIII, ch. 271, subch. J, PATHOGENS AND VECTOR ATTRACTION REDUCTION, app A
This appendix cited in 25 Pa. Code § 273.513 (relating to sewage sludge).