This document summarizes regulations for biosolids from wastewater treatment under Title 40 of the Code of Federal Regulations (CFR) Part 503. Biosolids must meet pollution concentration limits for heavy metals, as well as pathogen and vector attraction reduction requirements. There are two pathogen reduction classifications - Class A requires eliminating measurable pathogens, while Class B significantly reduces pathogens. Various treatment processes can achieve Class A or B, such as composting or digestion. Vector attraction reduction aims to eliminate pathogens, destroy their food source, and prevent regrowth. Biosolids meeting all standards are considered Exceptional Quality.

1. Biosolids Regulations
WATR-082: ADVANCED WASTEWATER TREATMENT
SPRING 2019

2. Biosolids
Treated solids
from wastewater
operations
Can be
disposed or
recycled
beneficially
Grit &
screenings – are
not considered
as biosolids
Must meet
standards under
Title 40 CFR
Part 503
Rich in nutrients
and substantial
organic content
Most common
biosolids
management
method – Land
Application
Utilizes this
biosolids attribute

3. CFR Title 40 Part 503 Requirements
Each of the following three standards must be met
POLLUTION
CONCENTRATIO
N LIMITS
PATHOGEN
REDUCTION
STANDARDS
VECTOR
ATTRACTION
REDUCTION

4. Pollutant Concentration Limits
Sludge exceeding Ceiling Concentration
Thresholds cannot be classified as biosolids
Cannot be
land
applied
Stipulation on concentration levels of ten heavy metals listed Pollutant
Arsenic
Cadmium
Copper
Lead
Mecury
Molybdenum
Nickel
Selenium
Zinc
Biosolids at or below the Pollutant Concentration Limit are
– High Quality Biosolids
Fewer
restrictions

5. Pathogen Reduction Requirement
Biosolids are classified based upon level of pathogen reduction
during sludge stabilization
• Solids are free of measurable pathogens
• No pathogen related site restriction – including home
& gardens
• Approved processes - Process to Further Reduce
Pathogens (PFRP), which are approved to meet
Class A standards:
• Heat Treatment
• Composting
• Thermophilic aerobic digestion
Pathogens are disease
causing organisms
• Pathogen levels reduced to levels unlikely to cause
threat to public health
• Site restriction imposed to protect public health
• Approved processes - Process to Significantly
Reduce Pathogens (PSRP), which are approved to
meet Class B standards:
• Aerobic & anaerobic digestion
• Air drying
• Composting
Class A Biosolids Class B Biosolids

6. Vector Attraction Reduction Requirement
Vectors are agents that can
transfer/transmit pathogens
Required of all biosolids – no exceptions for
pathogen class
Rodents Birds Insects
Options for
meeting Vector
Reduction
Approach 1: Specifying stabilization process
Example: Digestion and Alkaline Addition
Approach 2: Specifying biosolids injection or
incorporation process
Vector attraction reduction requirements
aim to:
• Eliminate pathogens
• Destroy pathogen’s food source, and
• Prevent pathogen regrowth
Meeting
minimum of
38% VS
destruction
during
sludge
stabilization
Most common method of demonstrating complianc

7. Exceptional Quality (EQ) Biosolids
• Exceptional Quality (EQ) Standard Biosolids must meet all of
the following:
1. Pollutant concentration limits
2. Class A requirements
3. Vector attraction reduction standards
• Application of EQ biosolids is almost unrestricted