Q&As Regarding the WERF Report:
It would appear waste disposal scientists have a complete disregard for the intelligence of the public, and have no
qualms about lying to the public. Witness the report on viable, but non-culturable bacteria in sludge they playfully call
biosolids. Then we have to wonder why it has taken 25 years, according to the report, to discover the viable, but
Lets look at seven points in this question and answer document.
1. How do wastewater treatment plant processes kill pathogens in wastewater treatment solids?
As the study indicates, since the 1980, the treatment processes are designed to make one non-pathogenic bacteria
non-detectable (i.e. Viable, but non-culturable) by standard culture methods (SCM)..
2. These forms of treatment are designed to kill disease-causing microscopic organisms (pathogens).
Treatment processes are not designed to kill pathogens. Class B standards allow culturable fecal coliform levels of
two billion cfu per kilogram of sludge. Class A standards allow culturable fecal coliform levels of one million cfu per
kilogram of sludge.
3. In addition, the National Academy of Sciences has reviewed current practices, public health concerns,
and regulatory standards and concluded that "the use of these materials in the production of crops for
human consumption, when practiced in accordance with existing federal guidelines and regulations,
presents negligible risk to the consumer, to crop production, and to the environment."
The WERF study on viable, but non-culturable phenomenon proves that disposal is not in accordance with existing
federal guidelines.The scientific statement by the National Academy of Science is very blunt: FINDINGS,"-----the
remaining uncertainty for complex mixtures of chemical and biological agents is sufficient to preclude the
development of risk-management procedures that can reliability result in acceptable levels of risk." (5)
4. In addition, an epidemiological study of the health of farm families using biosolids found that the use of
biosolids is safe
Actually the epidemiological study, Municipal Sewage Sludge Application on Ohio Farms: Health Effects, was never
competed, even though WEF has been quoting it for years. And there was a disclaimed against using the results
for sludge with higher levels of disease organisms, higher disposal rates and larger acreages. And it referenced a
study which indicate a positive cycle of infection from humans to sludge to cattle and back to humans.
5. U.S. EPA reviewed extensive data throughout the world, including findings from thousands of field trials
and laboratory experiments, on the human health and environmental impacts from the use or disposal of
In his 2004 paper, Evaluation of bacteriological indicators of disinfection for alkaline treated biosolids, EPA's Mark
Meckes, cautioned, "Again, it can be stated that lime treatment did not significantly reduce the number of spore
forming bacteria." (4) In a 1982 EPA study, M. C. Meckes' noted, "In 1959, Wantanabe (31) discovered that some
Escherichia coli strains could transfer antibiotic-senstive strains of shigella spp. Subsequent research has
demonstrated that bacteria carrying transmissible R-factors (DNA/RNA) are responsible for the spread of multiple
antibiotic resistence among members members of the Entero-bacteriaceae (such as E. coli, Samonella typi, and
Shigella dysenteriae) Aeromonas and Yersinis species (4), Pseudomonas, and Vibro cholerae (34),"(35)
6. More than four decades of scientific research and the excellent health histories of the personnel who
work at wastewater treatment plants, who land apply biosolids, and of the farmers who use biosolids
underscore the safety of biosolids when managed in accordance with federal regulations.
WASTEWATER INDUSTRY -- the most dangerous career field Hadeed reported that the wastewater industry has
retained its number one status as the most dangerous career field based on the results of the 1986 Annual WPCF
(former name of WEF) Safety Survey. Actually, farming is a much more dangerous career now EPA/WEF/WERF
assure farmers that sludge is safe with no disease causing organisms or dangerous chemicals in it. Of course, WEF
has spent millions of dollars trying to discredit the long list of victims -- some of them farmers.
7. The researchers also suggest some simple chemical additions to the sludge cake, such as a low-dose of
lime, could be used to control reactivation and regrowth.
See item 5.
In 1973, John Walker, retired head of EPA sludge program, who was with the USDA at that time, explained to EPA
that non-detection of Salmonella did not mean the bacteria were dead. USDA research showed that liming sludge, or
liming the soil, only inactivated Salmonella for about 30 days. Then there was regrowth to the original levels.. EPA
also noted in the 1989 proposed 503 sludge regulation that there could be explosive regrowth of Salmonella.
(National Association of State Universities and Land Grant Colleges, 1973)".
8. The Water Environment Federation is assembling a task force of scientists and engineers with a wide
variety of backgrounds and perspectives to provide a consensus-based evaluation of the implications
of the WERF study for public health protection, effective operational practices, and monitoring and
After 25 years these waste disposal scientists and engineers still have not done a literature review and are looking
for more government funding to do more research to do a consensus-based evaluation. What happened to
WEF’s Q&As Regarding the WERF Report:
“Examination of Reactivation and Regrowth of Fecal Coliforms in Centrifuge
Dewatered, Anaerobically Digested Sludges”
What is the issue here?
A recent research project based on a small sampling of wastewater treatment plants indicated that fecal coliform
bacteria may reactivate during certain biosolids treatment processes.
Why is this important?
The concentration of fecal coliform bacteria is used as an indicator of the average
amounts of bacterial and viral pathogens in biosolids treated by biological processes.
Some wastewater treatment facilities test for the presence of these indicator organisms to
assure compliance with the U.S. EPA federal regulations that govern biosolids use and
disposal (Title 40 of the Code of Federal Regulations, Part 503). Testing for fecal
coliforms is one of three options available to wastewater agencies to demonstrate
compliance with the Class B pathogen requirements of these regulations.
Who conducted the research?
The research was sponsored by the Water Environment Research Foundation (WERF) and conducted by scientists at
the District of Columbia Water and Sewer Authority and Bucknell University.
Where was it conducted?
This initial research phase collected samples from seven out of 16,000 U.S. wastewater
treatment plants. Samples from four of those plants indicated possible bacterial
reactivation, while three did not. All of the facilities at which testing was performed used
anaerobic digestion followed by dewatering using high-solids centrifuges for solids
processing. While many plants use anaerobic digestion, there are numerous alternative
means of dewatering, such as belt filter presses and standard centrifuges
How do wastewater treatment plant processes kill pathogens in wastewater treatment solids?
There are five approved processes to significantly reduce pathogens in sewage sludge.
They include aerobic and anaerobic digestion, air drying, composting, and lime
stabilization. These forms of treatment are designed to kill disease-causing microscopic
organisms (pathogens). Biosolids treated using these processes are considered to be
Class B with respect to pathogen destruction. While Class B biosolids may contain some
pathogens, restrictions on crop harvesting, animal grazing, and public access ensure
pathogen exposure is further reduced by environmental factors.
There are six approved processes for demonstrating Class A pathogen reduction. These
processes further reduce pathogens and therefore no additional treatment or site
restrictions are required by the regulations to protect public health and the environment.
What, according to the study, appears to be happening in this treatment process?
The WERF research, while limited in scope, suggests a potential that high-solids
centrifuge dewatering following anaerobic digestion, can, in some instances, result in the
reactivation of fecal coliform bacteria. The study did not determine the mechanisms for
any reactivation or regrowth.
How is compliance with the current pathogen requirements of federal regulations determined?
Each of the following processes are options under Part 503 for Class B biosolids testing.
The WERF investigators, however, used a competitive polymerase chain reaction (cPCR)
method that looked at DNA mapping to explain the regrowth-reactivation phenomenon.
The Part 503 regulations (Subpart D) provide three options or alternatives for facilities to
demonstrate compliance with Class B pathogen requirements:
Alternative 1: Test for fecal coliform density as an indicator for all pathogens to
demonstrate the biosolids meet the regulatory limits.
Alternative 2: Treat the biosolids in one of the five EPA-approved Processes to
Significantly Reduce Pathogens (PSRP).
Alternative 3: Treat the biosolids in a process equivalent to one of the PSRPs, as
determined by the permitting authority.
Monitoring after treatment is not required if Alternative 2 is selected; the biosolids are
considered in compliance with the regulations if the biosolids are treated according to the
specifications provided in Appendix B of Part 503.
Regardless of the Class B option chosen, the Part 503 regulations also include mandatory
site restrictions that prevent crop harvesting, animal grazing, and public access for a
certain period of time, all of which are designed to ensure additional protection of public
health and the environment.
How do we know that the EPA-approved processes for treating biosolids are safe?
During the development of the 40 CFR Part 503 Regulation for the Use or Disposal of
Sewage Sludge (Biosolids) (1993), U.S. EPA reviewed extensive data throughout the
world, including findings from thousands of field trials and laboratory experiments, on
the human health and environmental impacts from the use or disposal of biosolids. Field
trials on biosolids have been conducted in the United States and other countries for at
least 40 years. Some biosolids sites have undergone repeated application of biosolids for
nearly 30 years. Information gathered from monitoring these field trials and biosolids
sites indicates no environmental degradation or human health effects when used in
accordance with federal criteria.
In addition, the National Academy of Sciences has reviewed current practices, public
health concerns, and regulatory standards and concluded that "the use of these materials
in the production of crops for human consumption, when practiced in accordance with
existing federal guidelines and regulations, presents negligible risk to the consumer, to
crop production, and to the environment." In addition, an epidemiological study of the
health of farm families using biosolids found that the use of biosolids is safe.
Doesn’t this study confirm the claims of health problems that have been heard over the years?
No. This is a preliminary study focused on a small number of treatment plants. EPA
continues to believe that the pathogen requirements and operational standards of Subpart
D of the 40 CFR Part 503 regulations are protective of public health. More than four
decades of scientific research and the excellent health histories of the personnel who
work at wastewater treatment plants, who land apply biosolids, and of the farmers who
use biosolids underscore the safety of biosolids when managed in accordance with federal
What happens to the fecal coliform levels in biosolids during storage?
Studies conducted on stored biosolids indicate there is significant fecal coliform “die off”
during prolonged storage. Many treatment plants store biosolids for long periods before
Did the study provide any insight on possible mitigation or control strategies?
The study results provide some insight into possible control strategies. For example, a
multi-stage thermophilic process was able to completely destroy the fecal coliforms and
Escherichia coli, suggesting that reactors in series or in more general terms, reactor
hydraulics, may be an important factor. The researchers also suggest some simple
chemical additions to the sludge cake, such as a low-dose of lime, could be used to
control reactivation and regrowth. They also note that longer-term storage could be a
strategy to reduce fecal coliforms to desired levels.
Will utilities or municipalities need to modify their existing biosolids management practices?
It is important to remember that this study was conducted only at facilities that use
anaerobic digestion followed by high-solids centrifugation. Plants that do use these
processes will be closely monitoring the findings of this ongoing research as part of their
commitment to public health protection through safe biosolids management practices.
The next phase of the study will provide additional insights. Some potential
modifications, identified by the researchers, such as longer storage times or lime
stabilization, can be accomplished by many treatment plants without significant expense.
Other process changes could result in major expenses for new equipment or facilities.
Why is WERF releasing this study?
The Water Environment Research Foundation is dedicated to advancing science and
technology regarding water quality issues as they affect water resources, the atmosphere,
the land, and quality of life.
WERF subscribers are utilities and municipalities, environmental engineering and
consulting firms, government agencies, equipment manufacturers, and industrial
organizations, all with a common interest in promoting research and development in
water quality science and technology.
Is more research being conducted?
Additional research is currently being conducted by WERF to better define the conditions
under which these increases in fecal coliform are likely to occur, the extent of this
phenomenon, and options for wastewater treatment facilities to consider if bacterial
concentration increases are observed.
What does WEF plan to do in response to the study?
The Water Environment Federation is assembling a task force of scientists and engineers
with a wide variety of backgrounds and perspectives to provide a consensus-based
evaluation of the implications of the WERF study for public health protection, effective
operational practices, and monitoring and testing. The findings of the task force will be
available by the end of August 2006. WEF, along with WERF, and EPA remain
committed to continuing research on issues related to biosolids management and the
development and dissemination of best practices based on the results of this research.