Section R18-9-1006. Class A and Class B Pathogen Reduction Requirements

A.      An applicator shall ensure that all biosolids applied to land meet Class A or Class B pathogen reduction requirements at the time the biosolids are:

1.        Placed on an active sewage sludge unit unless the biosol- ids are covered with soil or other material at the end of each operating day, or

2.        Land applied.

B.       Biosolids that are sold or given away in a bag or other con- tainer for land application, or that are applied on a lawn or home garden, shall meet the Class A pathogen reduction requirements established in subsection (D).

C.      Land on which biosolids with Class B pathogen reduction requirements are applied is subject to the use restrictions established in R18-9-1009.

D.      Biosolids satisfy the Class A pathogen reduction requirements when the density of fecal coliform is less than 1000 Most Probable Number per gram of total solids (dry-weight basis), or the density of Salmonella sp. bacteria is less than three Most Probable Number per four grams of total solids (dry-weight basis), and any one of the following alternative pathogen treat- ment options is used:

1.        Alternative 1. The pathogen treatment process meets one of the following time and temperature requirements:

a.         When the percent solids of the biosolids are seven percent or greater, the temperature of the biosolids shall be held at 50° C or higher for at least 20 min- utes. The temperature and time period is determined using the equation in subsection (D)(1)(b), except when small particles of the biosolids are heated by either warmed gases or an immiscible liquid;

b.        When the percent solids of the biosolids are seven percent or greater, and small particles of the biosol- ids are heated by either warmed gases or an immisci- ble liquid, a temperature of 50° C or higher shall be held for 15 seconds or longer. The temperature and time period is determined using the following equa- tion:

D =  -----                       -

 

131, 700, 000

--------------------------- 10[0.1400t]

D = time in days, and

t = temperature in degrees Celsius;

c.         When the percent solids of the biosolids are less than seven percent, the temperature of the biosolids is 50° C or higher and the time period is 30 minutes or lon- ger. The temperature and time period shall be deter- mined using the following equation:

D =                    --

 

50, 070, 000

---------------------------- 10[0.1400t]

D = time in days, and

t = temperature in degrees Celsius; or

d.        When the percent solids of the biosolids are less than seven percent, and the time of heating is at least 15 seconds, but less than 30 minutes, the time and tem- perature is determined using the following equation:

D =  -----                 -

 

131, 700, 000

--------------------------- 10[0.1400t]

D = time in days, and

t = temperature in degrees Celsius.

2.        Alternative 2. The pathogen treatment process meets all the following parameters:

a.         The pH of the quantity of biosolids treated is raised to 12 or higher and held at least 72 hours;

b.        During the period that the pH is above 12, the tem- perature of the biosolids is held above 52° C for at least 12 hours; and

c.         At the end of the 72-hour period during which the pH is above 12, the biosolids are air dried to achieve a percent solids in the biosolids greater than 50%.

3.        Alternative 3. The following conditions are met:

a.         The biosolids, before pathogen treatment and until the next monitoring event, have an enteric virus den- sity less than one plaque-forming unit for four grams of total solids (dry-weight basis);

b.        The biosolids, before pathogen treatment and until the next monitoring event, have a viable helminth ova density less than one for four grams of total sol- ids (dry-weight basis); and

c.         Once the density requirements in subsections (D)(3)(a) and (D)(3)(b) are consistently met after pathogen treatment and the values and ranges of the pathogen treatment process used are documented, the biosolids continue to be Class A with respect to enteric viruses and viable helminth ova when the values for the pathogen treatment process operating parameters are consistent with the previously docu- mented values or ranges of values.

4.        Alternative 4. The following requirements are met at the time the biosolids are used or disposed or at the time the biosolids are prepared for sale or given away in a bag or other container for application to the land:

a.         The biosolids have an enteric virus density less than one plaque-forming unit for four grams of total sol- ids (dry-weight basis), and

b.        The biosolids have a viable helminth ova density less than one for four grams of total solids (dry- weight basis).

5.        Alternative 5. Composting.

a.         Use either the within-vessel or the static-aerated-pile composting method, maintaining the temperature of the biosolids at 55° C or higher for three days; or

b.        Use the windrow composting method, maintaining the temperature of the biosolids at 55° C or higher for at least 15 days. The windrow shall be turned at least five times when the compost is maintained at 55° C or higher.

6.        Alternative 6. Heat drying. The biosolids are dried by direct or indirect contact with hot gases to reduce the moisture content to 10% or lower by weight. During the process:

a.         The temperature of the sewage sludge particles shall exceed 80° C, or

b.        The wet bulb temperature of the gas as the biosolids leave the dryer shall exceed 80° C.

7.        Alternative 7. Heat treatment. The quantity of liquid bio- solids treated are heated to a temperature of 180° C or higher for at least 30 minutes.

8.        Alternative 8. Thermophilic aerobic digestion. Liquid biosolids are agitated with air or oxygen to maintain aero- bic conditions and the mean cell residence time of the biosolids is 10 days at 55 ° to 60° C.

9.        Alternative 9. Beta ray irradiation. Biosolids are irradi- ated with beta rays from an accelerator at dosages of at least 1.0 megarad at room temperature (approximately 20° C).

10.     Alternative 10. Gamma ray irradiation. Biosolids are irra- diated with gamma rays from certain isotopes, such as 60Cobalt and 137Cesium at dosages of at least 1.0 mega-

rad at room temperature (approximately 20° C).

11.     Alternative 11. Pasteurization. The temperature of the biosolids is maintained at 70° C or higher for at least 30 minutes.

12.     Alternative 12. The Director shall approve another pro- cess if the process is equivalent to a Process to Further Reduce Pathogens specified in subsections (D)(5) through (D)(11),  as determined  by the  EPA Pathogen Equivalency Committee.

E.       Biosolids satisfy the Class B pathogen reduction requirements when the biosolids meet any one of the following options:

1.        Alternative 1. The geometric mean of the density of fecal coliform in seven representative samples is less than either 2,000,000 Most Probable Number per gram of total solids (dry-weight basis), or 2,000,000 colony forming units per gram of total solids (dry-weight basis);

2.        Alternative 2. Air drying. The biosolids are dried on sand beds or paved or unpaved basins for at least three months. During at least two of the three months, the ambient aver- age daily temperature is above 0° C;

3.        Alternative 3. Lime stabilization. Sufficient lime is added to the biosolids to raise the pH of the biosolids to 12 after at least two hours of contact;

4.        Alternative 4. Aerobic digestion. The biosolids are agi- tated with air or oxygen to maintain aerobic conditions for a specific mean cell residence time at a specific tem- perature between 40 days at 20° C and 60 days at 15° C;

5.        Alternative 5. Anaerobic digestion. The biosolids are treated in the absence of air for a specific mean cell resi- dence time at a specific temperature between 15 days at 35° C to 55° C and 60 days at 20° C;

6.        Alternative 6. Composting. Using the within-vessel, static-aerated-pile or windrow composting methods, the temperature of the biosolids is raised to 40° C or higher for five consecutive days. For at least four hours during the five days, the temperature in the compost pile exceeds 55° C; or

7.        Alternative 7. The Director shall approve another process if it is equivalent to a Process to Significantly Reduce

Pathogens specified in subsections (E)(2) through (E)(6), as determined by the EPA Pathogen Equivalency Com- mittee.

Historical Note

New Section recodified from R18-13-1506 at 7 A.A.R. 2522, effective May 24, 2001 (Supp. 01-2). Amended by

final rulemaking at 7 A.A.R. 5879, effective December 7,

2001 (Supp. 01-4). Amended by final rulemaking at 8

A.A.R. 4923, effective January 5, 2003 (Supp. 02-4).