QUESTIONS WITH ANSWERS
VIABLE, BUT NON-CULTURABLE DISEASE CAUSING ORGANISMS STUDY
The implication of this background information document is that WEF and WERF are two separate
and independent entities and the waste disposal scientists have never done a literature review on
disease causing organisms. But they are going to spent government money to do more research.
And they are beginning to be scared of being caught in years of lies!
This study is an example of our commitment to build on the extensive body of science in this field, which will lead to
enhanced processes, testing, and operational procedures.
It is important to note that this research was initiated by the wastewater community based on priorities developed in a
multi-stakeholder research summit. 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
Water Environment Federation
Background Information Regarding WERF Study
“Examination of Reactivation and Regrowth of Fecal Coliforms in Centrifuge
Dewatered, Anaerobically Digested Sludges”
A recently published Water Environment Research Foundation (WERF) study reported
levels of fecal coliform bacteria in dewatered solids at seven wastewater treatment
facilities. The study is the first phase of research initiated by wastewater professionals as
part of ongoing efforts to apply the most effective practices to protect public health and
At four of the seven facilities studied, higher levels of fecal coliforms were detected after
dewatering in high solids centrifuges than before this dewatering treatment. At three
facilities no increase was observed. One potential explanation for the finding at the
facilities that showed an increase in bacterial counts is that fecal coliform bacteria were
reactivated during the dewatering process. Because of the limited scope of the study —
the initial research phase assessed the operations of only seven of 16,000 U.S. wastewater
treatment plants — further study is warranted.
Many wastewater treatment plants use digesters that treat wastewater sludge to a specific
temperature for a designated time period, along with other forms of treatment, to kill
disease-causing microscopic organisms (pathogens).
Fecal coliform bacteria concentrations are 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 ensure
compliance with the U. S. Environmental Protection Agency (EPA) regulations that
govern biosolids use and disposal (Title 40 of the Code of Federal Regulations, Part 503).
Testing for fecal coliform bacteria is one of three options available to wastewater
agencies to demonstrate compliance with the Class B pathogen requirements of these
This initial research, while limited in scope, raises a question as to whether high-solids
centrifuge dewatering after anaerobic digestion, can result in the reactivation of fecal
coliform bacteria. The study did not determine the mechanisms for reactivation and
regrowth of fecal coliform bacteria.
According to WERF, a follow-on phase of research is already underway to help define
the nature and extent of this phenomenon and to propose actions for wastewater treatment
facilities. In addition, the Water Environment Federation (WEF) is assembling a task
force that will evaluate the initial study’s implications and related operational and process
options. This information will be available to WEF members and wastewater treatment
facilities by the end of August 2006.
Safe practices for the use of biosolids as an agricultural fertilizer are based on decades of
ongoing research and practical experience. The treatment processes and land application
site restrictions required by EPA and additional state regulations continue to provide
multiple layers of protection for human and animal health and for the environment.
The thousands of municipalities and utilities that treat the public’s wastewater are
engaged in ongoing research to enhance our ability to protect public health and the
environment. This study is an example of our commitment to build on the extensive body
of science in this field, which will lead to enhanced processes, testing, and operational
It is important to note that this research was initiated by the wastewater community based
on priorities developed in a multi-stakeholder research summit. 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