Iowa Administrative Code › Agency 567 - Environmental Protection Commission › Title IV - Wastewater Treatment and Disposal › Chapter 67 - Standards for the Land Application of Sewage Sludge › Rule 567-67.8 - Land Application Requirements for Class Ii Sewage Sludge

Current through Register Vol. 47, No. 3, July 24, 2024
(1)
Class
				II sludge criteria.
Class II sewage sludge is sewage sludge that meets
				the pollutant concentrations in paragraph 67.8(1)
"a,"
the
				pathogen reduction standards in paragraph 67.8(1)
"b,"
and the
				vector attraction reduction requirements in paragraph
				67.8(1)
"c"
below.
a.
Pollutant concentrations for Class II sewage sludge.
The
				concentration of any pollutant in the sewage sludge shall not exceed the
				ceiling concentration for the pollutant in Table 3.
TABLE 3-CEILING CONCENTRATIONS
Pollutant
Ceiling Concentration milligrams per
								kilogram*
Arsenic
75
Cadmium
85
Copper
4300
Lead
840
Mercury
57
Molybdenum
75
Nickel
420
Selenium
100
Zinc
7500
*Dry weight basis
b.
Pathogen reduction requirements
				for Class II sewage sludge.
The sewage sludge shall meet one of the
				following three alternatives.
(1) Seven
				samples of the sewage sludge shall be collected at the time the sewage sludge
				is disposed, and the geometric mean of the density of fecal coliform shall be
				less than 2,000,000 Most Probable Number per gram of total solids (dry weight
				basis).
(2) Sewage sludge shall be
				treated in one of the Processes to Significantly Reduce Pathogens (PSRP)
				described in 567-67.11 (455B).
(3) Sewage sludge shall be treated in a
				process that is equivalent to a Process to Significantly Reduce Pathogens
				(PSRP), as determined by the department.
c.
Vector attraction reduction
				requirements for Class II sewage sludge.
The sewage sludge shall meet
				one of the following vector attraction reduction requirements.
(1) The mass of volatile solids in the sewage
				sludge shall be reduced by a minimum of 38 percent.
(2) Digest a portion of the previously
				anaerobically 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. If, 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) Digest a portion of the previously
				aerobically digested sewage sludge that has a percent solids of 2 percent or
				less aerobically in the laboratory in a bench-scale unit for 30 additional days
				at 20 degrees Celsius. If, 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, measured at 25 degrees Celsius, 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 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) Sewage sludge shall
				be injected below the surface of the land and no significant amount of the
				sewage sludge shall be present on the land surface within one hour after the
				sewage sludge is injected.
(10)
				Sewage sludge applied to the land surface or placed on a surface disposal site
				shall be incorporated into the soil within six hours after application to or
				placement on the land.