Wyoming Administrative Code › Agency 020 - Environmental Quality, Dept. of › Sub-Agency 0011 - Water Quality › Chapter 15 - USE OF SURFACE DISPOSAL OF BIOSOLIDS, APP. A-C › Part C - SURFACE DISPOSAL › Appendix B - Pathogen Treatment Processes

Current through July 13, 2024
(a) Process to Significantly Reduce Pathogens
					 (PSRF).
(i) Aerobic digestion. Biosolids are 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.
(ii) Air drying. Biosolids are dried on sand beds or on
					 paved or unpaved basins. The biosolids dries for a minimum of three months.
					 During two of the three months, the ambient average daily temperature is above
					 zero degrees Celsius.
(iii) Anaerobic digestion. Biosolids are 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.
(iv) Composting. Using either the within-vessel, static
					 aerated pile, or windrow composting methods, the temperature of the biosolids
					 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.
(v) Lime stabilization. Sufficient lime is added to the
					 biosolids to raise the pH of the biosolids to 12 after two hours of
					 contact.
(b) Process to Further Reduce Pathogens (PFRP).
(i) Composting. Using either the within-vessel composting
					 method or the static aerated pile composting method, the temperature of the
					 biosolids is maintained at 55 degrees Celsius or higher for three days.
Using the windrow composting method, the temperature of the
					 biosolids 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.
(ii) Heat drying. Biosolids are dried by direct or indirect
					 contact with hot gases to reduce the moisture content of the biosolids to ten
					 percent (10%), or lower. Either the temperature of the biosolids particles
					 exceeds 80 degrees Celsius or the wet bulb temperature of the gas in contact
					 with the biosolids as the biosolids leaves the dryer exceeds 80 degrees
					 Celsius.
(iii) Heat treatment. Liquid biosolids are heated to a
					 temperature of 180 degrees Celsius or higher for 30 minutes.
(iv) Thermophilic aerobic digestion. Liquid biosolids are
					 agitated with air or oxygen to maintain aerobic conditions and the mean cell
					 residence time of the biosolids is tne (10) days at 55 to 60 degrees
					 Celsius.
(v) Beta ray irradiation. Biosolids are irradiated with
					 beta rays from an accelerator at dosages of at least 1.0 megarad at room
					 temperature (ca. 20 degrees Celsius).
(vi) Gamma ray irradiation. Biosolids are irradiated with
					 gamma rays from certain isotopes, such as Cobalt 60 and Cesium 137, at room
					 temperature (ca. 20 degrees Celsius).
(vii) Pasteurization. The temperature of the biosolids is
					 maintained at 70 degrees Celsius or higher for 30 minutes or
					 longer.