types of requirements must be demonstrated separately.
Therefore, demonstration that a requirement for reduced vector
attraction has been met does not imply that a pathogen reduction
requirement also has been met, and vice versa.
Pathogen Reduction Requirements
Sewage Sludge [503.32(a) and (b)]. The pathogen
reduction requirements for sewage sludge are divided into two
categories: Class A and Class B. These requirements use a
combination of technological and microbiological requirements to
ensure reduction of pathogens.
The implicit goal of the Class A requirements is to
reduce the pathogens in sewage sludge (including enteric viruses,
pathogenic bacteria, and viable helminth ova) to below detectable
levels. The implicit goal of the Class B requirements is to
ensure that pathogens have been reduced to levels that are
unlikely to pose a threat to public health and the environment
under the specific use conditions. For Class B solids that are
applied to land, site restrictions are imposed to minimize the
potential for human and animal contact for a period of time
following land application, until environmental factors have
further reduced pathogens. Class B solids cannot be sold or
given away in bags or other containers for application to the
land. There are no site restrictions for Class A solids.
Domestic Septage [503.32(c)]. Domestic septage is
a form of sewage sludge. The requirements for domestic septage
vary depending on how it is used or disposed. Domestic septage
applied to a public contact site, lawn, or home garden must meet
the same requirements as other forms of sewage sludge. Separate,
less complicated requirements for pathogen reduction, apply to
domestic septage applied to agricultural land, forests, or
reclamation sites. These requirements include site restrictions
to reduce the potential for human contact and to allow for
restrictions only on harvesting crops. No pathogen requirements
apply if domestic septage is placed on a surface disposal site.
Vector Attraction Reduction Requirements [503.33].
Subpart D specifies 12 options to demonstrate reduced vector
attraction. Eight of the options apply to sewage sludges that
have been treated in some way to reduce vector attraction (e.g.,
aerobic or anaerobic digestion, composting, alkali addition, and
drying). These options consist of operating conditions or tests
to demonstrate that vector attraction has been reduced in the