Understanding Class A and
Pathogen Equivalency
Mark C. Meckes
U.S. EPA
Office of Research and Development
Senior Research Microbiologist
Chair: Pathogen Equivalency Committee
Northwest Biosolids Management Association
Annual Conference
Chelan, WA
September 19-21, 2010
Overview
• Wastewater sources
• Classifying biosolids and treatment alternatives
• Vector attraction reduction
• Process equivalency
• The Pathogen Equivalency Committee (PEC)
• Web resources: www.epa.gov/nrmrl/pec
• The road to demonstrating equivalency (the process)
• Some of those on the road
• Research
SOURCES OF WASTEWATER &
ASSOCIATED MICROORGANISMS
Sources of
microorganisms
• Contributors to municipal
wastewater collection systems.





Homes.
Commercial establishments.
Hospitals.
Industries.
Storm water.
Human pathogens
• 1415 species of infectious
organisms.





538 bacteria and rickettsiae.
217 viruses.
307 fungi.
287 helminths.
66 protozoa.
Source: Taylor, Latham & Woolhouse, 2001
Pathogenic bacteria of
concern
AeromonasE
BurkholderiaE
Campylobacter
Clostridium perfringensI
E.coliE Pathogenic
Helicobacter pyloriE
Legionella
Leptospira*
Listeria
Mycobacterium
Neisseria meningitidisE
Pseudomonas
Salmonella
Shigella
StaphylococcusI
StreptococcusI
Vibrio cholerae*
Yersinia enterocolitica
Antibiotic resistant
bacteria
• Affect control of bacterial infections.
• Caused by:
 Prophylactic dosages in medicine.
 Recurring infections – increased doses.
 Prophylactic dosages in animal
husbandry.
 Discharges from manufacturing
processes.
 Genetic exchanges.
 Competitive advantage.
Biosolids: Schematic Representation
Treated
Discharge
Wastewater
Clarifier
Oxidation
Solids treatment
Solids treatments:
•Dewater and dispose
•Beneficial reuse
•Energy recovery
•Land application
Clarifier
CURRENT PRODUCTION & MANAGEMENT OF
SLUDGE/BIOSOLIDS
• Produce 7 MILLION DMT/Y
• 54 % IS LAND APPLIED/BENEFICIALLY USED
• 18 % IS SURFACE DISPOSED
Classification of sludge treatments
Federal Regulations
Federal Register Vol. 58, No. 32 February 19, 1993
Subpart D-Pathogens and Vector Attraction Reduction
•Class B – Some pathogens present. Site restrictions are required.
•Class A – Free of measurable pathogens. No site restrictions required.
•Vector Attraction Reduction is required regardless of Class.
40 CFR 503 Subpart D
Class B Alternatives
• Alternative 1 Monitoring of fecal coliform
 Seven samples of treated sewage sludge collected at the time
of use or disposal.
 Geometric mean of the samples must be less than 2 million
per gram dry weight.
• Alternative 2 Use of a PSRP process.





Aerobic digestion
Anaerobic digestion
Composting
Lime addition
Air drying
• Alternative 3 Use of processes equivalent to PSRP
Class B Processing Alternatives
Alternative
1 – Testing
Percentage of Total
Systems
27
2 – PSRP
71
3 – PSRP
Equivalent
2
PSRP PROCESS EMPLOYMENT
AEROBIC DIGESTION
• 36 %
ANAEROBIC DIGESTION
• 38 %
CHEMICAL (LIME)
•
COMPOSTING
• 12 %
OTHER
•
9%
5%
Class A vs.Class B
76%
12%
12%
A
B
?
CLASS A Approach
1. Thermal Treatment – Batch reactors or plug flow
conditions. Time at temperature restrictions
based upon solids content.
2. Alkaline Treatment + heat (≥52°)
3. Prior Testing for Enteric Virus & Viable Helminth
4. Routine monitoring of each batch of treated
sewage sludge.
5. Use one of the Processes to Further Reduce
Pathogens (PFRP) – composting, heat drying.
6. Use PFRP Equivalent Process.
Microbiological standards
(40 CFR 503)
• Class A:
At the time of use or disposal (dry weight) :
 1000 fecal coliform/g or <3 salmonellae/4g
 <1pfu enterovirus/4g
 <1viable helminth ova/4g
 Class B:
 Use of a PSRP or equivalent process or <2 million fecal
coliform/g at the time of use or disposal.
40 CFR 503 Subpart D
Class A Alternatives
• Alternative 1 (19 %) Time and temperature.
 Derived from experience with fluids; all parts of sludge must
meet the requirements for time and temperature.
 In general these processes are limited to batch reactors or
plug flow rather than continuous flow reactors.
• Alternative 2 (12 %) Alkaline treatment at elevated
temperature.
 The process partially described here is that of N-Viro’s PFRP
equivalent process.
• Alternative 3 (4 %) Monitoring.
 This is sometimes labeled a “self equivalency.”
 Demonstration of PFRP equivalency (Alternative 6)
40 CFR 503 Subpart D
Class A Alternatives
• Alternative 4 (9 %) AKA: Orphaned sludge rule.
 Limitations and/or concerns include the cost of analyses.
 Limited availability of qualified laboratories.
 Adequate sampling plan.
 Absence of enteric viruses and helminth ova does not insure
the absence of other pathogenic organisms.
• Alternative 5 (52 %) PFRP Processes.
 Composting, pasteurization, and heat drying are most
frequently used.
 Limitations of Add on Processes: (Like irradiation and
pasteurization) – Be aware of vector attraction concerns.
ALTERNATIVE 5: PFRP
PROCESSES TO FURTHER REDUCE PATHOGENS
Alternative 6 ~ Equivalent processes
•
Created in 1985 to provide technical expertise to permitting
authorities on PFRP/PSRP Equivalencies
• 11 members with direct or
related expertise and diverse
Pathogen
points of view
Equivalency Committee
Center for Disease Control
& Prevention (CDC)
U.S. EPA
Office of
Research &
Development
Regional
Offices
Office
of
Water
National Institute of
Occupational Safety & Health
National Center for
Environmental Health
Region VIII
National Exposure
Research Laboratory
Office of Science &
Technology
National Homeland Security
Research Center
Office of Wastewater
Management
National Risk Management
Research Laboratory (chair)
 Microbiology
 Virology
 Parasitology
 Medicine
 Environmental engineering
 Wastewater treatment
 Industrial hygiene
 Federal regulations
Requirements for Reducing
Vector Attraction
• Vector - Living organisms capable of
transmitting a pathogen from one living
organism to another.
• Intent: Decrease transport of pathogens
• Organisms most likely to serve as vectors
 Insects
 Rodents and other small mammals
 Birds
Vector Attraction Reduction Options
•
•
•
•
•
•
•
•
•
•
•
Reduction in volatile solids (>38%)
Additional anaerobic digestion (<17%)
Additional aerobic digestion (<15%)
Specific Oxygen Uptake Rate ≤ 1.5mg/hr/g
Aerobic process > 40°C
Addition of Alkali pH≥12 2hr, pH≥11.5 22hr
Moisture reduction stabilized solids - 75%
Moisture reduction unstabilized solids – 90%
Subsurface injection
Incorporation within 6 hours
Daily cover (surface disposal sites only)
VAR Usage by POTWs
Method
38% VSR
POTW Estimate
(based on 4500)
1535
SOUR
669
14 Day @ 40ºC
204
pH 12 – 22hr
448
Inject
588
Incorporate
361
VECTOR ATTRACTION
REDUCTION
• THE CALCULATION OF 38 PERCENT VOLATILE SOLIDS
REDUCTION IS NOT APPROPRIATE FOR COMPOST
• THE SOUR TEST SHOULD BE RUN ONLY ON AEROBICALLY
DIGESTED LIQUID SLUDGES PROCESSED BETWEEN 10 AND
30 DEGREES; THE SOUR TEST SHOULD BE RUN AT THE
TEMPERATURE AT WHICH THE SEWAGE SLUDGE WAS
PROCESSED
• THE SOUR TEST IS NOT APPROPRIATE FOR SOLIDS; IT
SHOULD NOT BE USED FOR COMPOST OR DRIED SLUDGE
PRODUCTS
VECTOR ATTRACTION
REDUCTION
• PRODUCTS THAT HAVE BEEN STABILIZED BY
ADDING LIME TO RAISE THE pH SHOULD BE
DISTRIBUTED AND USED BEFORE pH DROPS
BELOW 10.5
• HEAT-DRIED PRODUCTS SHOULD BE STORED
UNDER COVER SO THAT MOISTURE IS NOT REINTRODUCED
Alternative 6 ~ Equivalent processes
•
Created in 1985 to provide technical expertise to permitting
authorities on PFRP/PSRP Equivalencies
• 11 members with direct or
related expertise and diverse
Pathogen
points of view
Equivalency Committee
Center for Disease Control
& Prevention (CDC)
U.S. EPA
Office of
Research &
Development
Regional
Offices
Office
of
Water
National Institute of
Occupational Safety & Health
National Center for
Environmental Health
Region VIII
National Exposure
Research Laboratory
Office of Science &
Technology
National Homeland Security
Research Center
Office of Wastewater
Management
National Risk Management
Research Laboratory (chair)
 Microbiology
 Virology
 Parasitology
 Medicine
 Environmental engineering
 Wastewater treatment
 Industrial hygiene
 Federal regulations
www.epa.gov/nrmrl/pec
Website Resources
www.epa.gov/nrmrl/pec
Website Resources
How to Apply page
www.epa.gov/nrmrl/pec
Website Resources
• Contact permitting authority first if applicable
•
•
•
•
A must for site-specific cases
Specific region targeted
Treatment plant where testing will
occur has already been identified
Coordinator Locator page
• Permitting authority will
make initial contact with
PEC
• Contact PEC directly
otherwise
• General mailbox:
pec@epa.gov
QAPP
• QAPP = Quality Assurance Project Plan
•
•
Provides framework and details for sampling and analysis
Ensures the validity of the data
• Now REQUIRED!
• Prior agreement with PEC on QAPP will save time and $
• Head start on application
QAPP
www.epa.gov/nrmrl/pec
Website Resources
• QAPP page
•
•
•
•
QAPP guidelines - annotated outline
Example QAPPs
A checklist used by the PEC to review
A list of applicable analytical methods,
plus links
• Equivalency Criteria page
- Treatment time
- Temperature
- Chemical dosing
- pH
- %TS range
- etc.
• Provides QAPP objectives
• 4 necessary criteria:
Identify Critical Process Parameters
Verify Pathogen Reduction
Demonstrate scale-up
Provide Appropriate Documentation
(i.e., QAPP)
QAPP Phase
www.epa.gov/nrmrl/pec
Website Resources
PSRP Equivalency:
≥ 2 log red. FC*;
and
≤ 2,000,000 MPN or CFU/g TS
FC in treated sludge
• QAPP page
•
•
•
•
QAPP guidelines - annotated outline
Example QAPPs
A checklist used by the PEC to review
A list of applicable analytical methods,
plus links
PFRP Equivalency:
≥ 3 log red. enteric viruses;
≥ 2 log red. viable helminth
(Ascaris) ova;
• Equivalency Criteria page
≥ 3 log red. FC*;
and
• Provides QAPP objectives
≤ 1 pfu/4
g TS totaltime
enteric viruses;
- Treatment
• 4 necessary criteria:
≤ 3 viable helminth (Ascaris)
- Temperature
ova/4
g TS;
• Identify Critical Process Parameters
≤ 1,000- Chemical
MPN FC/ gdosing
TS or ≤ 3
• Verify Pathogen Reduction
MPN- Salmonella
spp./4 g TS
pH
• Demonstrate scale-up
- %TS range
*FC can be replaced by E. coli,
- etc.
• Provide Appropriate Documentation
Enterococcus, or Salmonella (PFRP only)
(i.e., QAPP)
QAPP Phase
www.epa.gov/nrmrl/pec
Website Resources
PSRP Equivalency:
≥ 2 log red. FC*;
and
≤ 2,000,000 MPN or CFU/g TS
FC in treated sludge
• QAPP page
•
•
•
•
QAPP guidelines - annotated outline
Example QAPPs
A checklist used by the PEC to review
A list of applicable analytical methods,
plus links
PFRP Equivalency:
≥ 3 log red. enteric viruses;
≥ 2 log red. viable helminth
(Ascaris)
Issues
withova;
spiking
• Equivalency Criteria page
≥3
log
red.
FC*;
make verification
and
• Provides QAPP objectives
difficult
at
full-scale.
≤ 1 pfu/4 g TS total enteric viruses;
• 4 necessary criteria:
≤ 3 viable helminth (Ascaris)
Lab-scale
ova/4
g TS;verification.
Identify Critical Process Parameters
≤ 1,000 MPN FC/ g TS or ≤ 3
Verify Pathogen Reduction
MPN
Salmonella
spp./4
g
TS
Use of surrogates may
Demonstrate scale-up
be
necessary.
*FC can be replaced by E. coli,
Enterococcus, or Salmonella (PFRP only)
Provide Appropriate Documentation
(i.e., QAPP)
www.epa.gov/nrmrl/pec
Website Resources
How to Apply page
• Application
Guidelines
• New Equivalency
Application
Package Form
• Ready-made fill-in
form
• summary information
& attachment list
• Detailed line-by-line
instructions
Autothermal Thermophilic
Aerobic Digestion (ATAD)
• ATAD is a two-stage, autothermal aerobic digestion
process. The stages are of equal volume. Treated sludge
amounting to 1/3 the volume of a stage is removed every
24 hours from the second stage as product. An equal
amount then is taken from the first stage and fed to the
second stage. Similarly, an equal amount of untreated
sludge is then fed to the first stage. In the 24-hour period
between feedings, the sludge in both stages is vigorously
agitated and contacted with air. Bio-oxidation takes place
and the heat produced increases the temperature. Sludge
temperature in the reactors averages between 56 and
57°C for ≥ a 16-hour period, while the overall hydraulic
residence time is 6 days.
Alkaline Stabilization
• Manchak process uses quicklime to
simultaneously stabilize and pasteurize
biosolids.
• Quicklime, or a combination of quicklime and
flyash, is mixed with dewatered biosolids at a
predetermined rate in a confined space. An
instant exothermic reaction is created in the
product wherein the pH is raised in excess of 12
after two hours of contact, in addition, the
temperature is raised in excess of 70°C for > 30
minutes.
OxyOzonation
• Operation occurs in a batch mode and under the following
conditions:






sludge temperature of > 20°C
sludge solids of < 6% TSS
pH during ozonation of 2.5 - 3.1
pH during nitrite contact of 2.6 - 3.5
ORP after ozonation of > 100 mV
nitrite dose of ≥ 670 mg (NO2)/1 sludge or 16 g (NO2)/kg sludge
solids, whichever is greater is to be mixed into the ozonated
sludge.
• Ozonation takes place in a pressure vessel at 60 psig.
On the road to equivalency
ID 2PAD SYSTEM
TWO PHASE
ANAEROBIC DIGESTION
Lyonnaise des Eaux’s Two-Phase
Thermo-Meso Feed Sequencing
Anaerobic Digestion Process
•Sewage sludge is treated in the absence of air in an acidogenic
thermophilic reactor and a mesophilic methanogenic reactor
connected in series.
•The mean cell residence time shall be at least 2.1 days (± 0.05 d) in
the acidogenic thermophilic reactor followed by 10.5 days (± 0.3 d) in
the mesophilic methanogenic reactor.
•Feeding of each digester shall be intermittent and occurring 4 times
per day every 6 hours.
•The mesophilic methanogenic reactor shall be fed in priority from the
acidogenic thermophilic reactor.
•Between two consecutive feedings, temperature inside the acidogenic
thermophilic reactor should be between 49°C and 55°C with 55°C
maintained during at least 2.8 hours.
•Temperature inside the mesophilic methanogenic reactor shall be
constant and at least 37°C.
PERFORMANCE OF 2PAD
SYSTEM PILOT PLANT
Schwing-Bioset
INFLUENCE OF TEMPERATURE, TIME, % AMMONIA, &
PRESSURE ON ASCARIS INACTIVATION
PEC’S RECOMMENDATION OF
The BIOSET PROCESS AS A PFRP
• The sludge is held at a temperature of 55̊C or greater for a
minimum of 25 minutes.
• The solids content of the sludge being treated is in the
range of 6% to 35%.
• The ammonia content in the reactor is 1% (10,000 mg/L) on
a volume basis.
• The pressure in the reactor is 30 psi.
• The amount of lime added is 0.55 to 0.75 lbs. lime to 1 dry
lb. of sludge.
• The amount of acid added is 8 to 10 lbs. per dry ton of
sludge.
• The pH is greater than 12.
CHARACTERISTICS OF BCR’s
NEUTRALIZER PROCESS
DISINFECTION CAPABILITY OF
BCR’s NEUTRALIZER PROCESS
Vermicomposting
Vermitech Process formerly
Granville, Pennsylvania
The MagnaGro Process
Research
•
•
•
•
•
Validated methods of analysis.
Indicator organisms relationship to pathogens.
Holding times, how long is reasonable?
Transport - air, soil and runoff.
Survival – natural attenuation factors.
WHAT WAS DISCUSSED
• Wastewater sources
• Classifying biosolids and treatment alternatives
• Vector attraction reduction
• Process equivalency
• The Pathogen Equivalency Committee (PEC)
• Web resources: www.epa.gov/nrmrl/pec
• The road to demonstrating equivalency (the process)
• Some of those on the road
• Research
Questions?
meckes.mark@epa.gov
www.epa.gov/nrmrl/pec