Pathogens, respectively) illustrate EPA's adoption of both a
process based and performance based regulatory strategy.
The Class A and B alternatives provide for performance based
approvals of certain levels of pathogen or indicator
organism reduction, if such reductions can be proven to be produced consistently by the process for which approval is being sought. The Class A and Class B alternatives also allow for the same process based options that were
originally established in the 1979 rule. If the treatment process is conducted within the parameters outlined in the
treatment alternatives, it is assumed to achieve the
required pathogen reductions. Management restrictions round out the regulatory strategy to hopefully, reduce any risk to human health that is not sufficiently safeguarded by the
Table 34
Class A Alternative Requirements
Alternative 1:
•Fecal Coliforms = less than 1000 MPN/g total
solids(dry wt.)
or
Salmonella sp. = less than 3 MPN/4 g total
solids(dry wt.)
and
•Temperature requirements met -
If sludge >7% solids and not heated by warm gases or an immiscible liquid, then 50°C or higher shall
be achieved for 20 min. or more. Exact
temp./time determined by the following equation:
D = 1.317x10* 2^q0.14001
where D = time in days t = temperature in °C
If >7% solids and heated by warm gas or immiscible
liquid, then 50°C or higher for 15 sec. or more
shall be achieved. Exact temp./time determined as
above.
If <7% solids and time period (t) is 15sec.< t < 30min., then temp./time determined as above.
If <7% solids and temperature is 50°C or higher
and time is 30 min. or longer, then exact
temp./time determined by the following equation:
D = 5.007X10''
ͣ
j^qO.MOCK Alternative 2:
•Same microbial standards as Alternative 1
and
•pH of sludge raised to above 12 and remains so for 72
hr. and
•the temperature of the sludge remains above 52°C for
12 hr. and
•after the 72 hr. period, sludge is air dried to achieve 50% solids or greater.
Table 34 (continued)
Class A Alternative Requirements
Alternative 3:
•Same microbial standards as alternative 1
and
•sludge analyzed prior to pathogen treatment to see if
it contains enteric viruses.
If the density is less than 1 pfu/4 g total solids
(dry wt.) •
or
If the density is greater than 1 pfu/4 g total solids, and is then treated (by a process that has been documented as able to meet enteric virus
standard) and achieves less than 1 pfu/4 g total
solids, and
•sludge analyzed prior to pathogen treatment to see if
it contains helminth ova.
If the density is less than 1 ova/4 g total solids
(dry wt.).
or
If the density is greater than 1 ova/4 g total solids, and is then treated (by a process that has been documented as able to meet helminth standard)
and achieves less than 1 ova/4 g total solids.
Alternative 4:
•Same microbial standard as Alternative 1
and
•enteric virus density is less than 1 pfu/4 g total
solids (dry wt.) at time of reuse/disposal, and
•helminth ova density is less than 1 ova /4 g total
solids (dry wt.) at time of reuse/disposal.
Alternative 5:
•Same microbial standard as Alternative 1
and
•the sewage sludge is treated in one of the Processes
to Further Reduce Pathogens (PFRP), in Appendix B,
before use/disposal. Alternative 6:
•Same microbial standard as Alternative 1
and
•the sewage sludge is treated in a process that is deemed equivalent to a Process to Further Reduce Pathogens (PFRP), as determined by the permitting authority, before reuse/disposal.
Table 35
Class B Alternative Requirements
Alternative 1:
The geometric mean for fecal coliform bacteria from seven samples of sludge collected at the time of
use/disposal must be less than 2x10* MPN/g total solids
(dry wt.)
or
less than 2x10'' CFU/g total solids (dry wt.)-
Alternative 2:
The sewage sludge is treated in one of the Processes to Significantly Reduce Pathogens (PSRP), in Appendix B,
before use/disposal. Alternative 3:
The sewage sludge is treated in a process that is
deemed equivalent to a Process to Significantly Reduce Pathogens (PSRP), as determined by the permitting
authority, before reuse/disposal.
Table 36
Class B Site Restrictions (for disposal/reuse Practice I)
Restriction l:
Food crops with harvested parts that touch the sewage sludge/soil mixture and are totally above the land
surface shall not be harvested for 14 months after the application of sewage sludge.
Restriction 2:
Food crops with harvested parts below the surface of
the land shall not be harvested for 20 months after the
application of sewage sludge when the sewage sludge remains on the land surface for four months or longer prior to incorporation into the soil.
Restriction 3:
Food crops with harvested parts below the surface of
the land shall not be harvested for 38 months after the
application of sewage sludge when the sewage sludge
remains on the land surface for less than four months
prior to incorporation into the soil.
Restriction 4:
Food crops, feed crops, and fiber crops shall not be harvested for 30 days after application of sewage
3. Establishment of Sludge Classes
For each Class A alternative, the density of fecal