Environmental Science & Engineering - www.esemag.com - June 2003
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Biosolids not affected by SARS virus
Government regulated treatment of biosolids eliminates all Coronavirus before any land applications occur
The Coronavirus that has been implicated as the likely
cause of SARS cannot be passed to humans or
animals through the spreading of biosolids as fertilizer
by farmers. So says the Water Environment
Association of Ontario (WEAO) which disputes the position
taken by the Sierra Club of Canada that there is a possible
link between the land application of biosolids and the
spreading of the virus that causes SARS. The Sierra Club
has used information related to wastewater and has tried to
apply that information to biosolids. This is a distortion of
the facts and is unfounded.
“Any link between SARS and biosolids is erroneous and
based on speculation, not science,” said Tony Petrucci,
WEAO President, in a news release May 26, 2003.
Even if the virus is present in wastewater, it will not survive
in the waste stream due to the level of biological treatment
and destruction that occurs in the wastewater treatment
facility. Further, the vigorous and long retention time
within the biosolids treatment process is designed to
destroy pathogenic and objectionable materials. The Water
Environment Research Foundation
(WERF) is currently conducting a
study on the Fate of Emerging
Pathogens in Biosolids and has
found that human viruses, such as
the Coronavirus, have their microbial
concentration reduced by 90%
of the initial detected level within
hours of being anaerobically digested.
SARS has not been found in
biosolids, and should not be found
after such high rates of treatment.
In Canada, wastewater is
processed in government regulated
treatment plants. Wastewater is
treated in process tanks for several
days before solids are transferred to
digesters where they are further
treated for a minimum 15 days to
produce biosolids. After this period,
these treated biosolids are applied
on agricultural land safely as fertilizer
under guidelines written by the
Ministries of Health, Environment,
and Agriculture and Food.
The Sierra Club is basing its claims on a statement
made by Hong Kong’s health secretary, Dr. Yeoh Engkiong,
that wastewater may be responsible for SARS
infecting residents of a high-rise apartment complex in
Hong Kong. Yet, public health officials in Hong Kong
traced the outbreak at the complex to a 33-year old man
from Guangdong province in China, where the original
outbreak began. The man visited his brother in the apartment
complex. The building has many small apartments.
“The close person-to-person contact in these residences
and in public areas such as elevators contributed to the
spread of the infection,” said Dr. Eng-kiong.
In a CTV News story, some scientists believe that the
outbreak in a Hong Kong apartment complex was as a
result of leaky wastewater pipes. When asked if a similar
situation could happen at home, Dr. Donald Low,
Microbiologist in-chief at Toronto’s Mount Sinai Hospital
reviewed the data and states that, “no, that was a very
unusual circumstance, and the structural defects that were
found in the apartment complex with a cross contamination
of the sewage pipes with water and in drain pipes was
really unusual”. Furthermore, Dr. Low suggests that the
virus could survive in diarrhea for up to four days. Other
scientists also suggest that the Coronavirus associated with
SARS is not known to survive longer than three to four
days.
Dr. Syed Sattar, a noted professor in the Department of
Biochemistry, Microbiology and Immunology at the
University of Ottawa, agrees that transfer of the virus that
causes SARS through wastewater is
unlikely. Dr. Sattar suggests that,
“even if the Coronavirus was found to
be excreted in feces, it may not survive
in the waste stream, since the dilution
factor in the sewage system is expected
to be immense and the Coronavirus
is most likely to lose its infectivity
quite rapidly in the waste stream and
in the sewage treatment process
itself ”. Furthermore, Dr. Sattar believes that the pattern of
spread of SARS seen thus far does not support its spread
from the feces of infected individuals.
Other experts support Dr. Sattar’s position, that it is
unlikely that SARS would be spread through wastewater
in North America, as it has done in Hong Kong.
“In North America, we have the best sanitary systems
anywhere, and we have great public health here,” said
Barbara Robinson-Dunn, Technical Director of
Microbiology at the William Beaumont Hospital in Royal
Oak, Michigan. “One of the keys to public health is (proper
handling of) bodily waste.”
“I find it unfortunate that an organization with the
stature of the Sierra Club would take advantage of the
SARS crisis and make negative statements against the
beneficial use of biosolids on agricultural land without
first consulting with water and wastewater treatment professionals,
scientists and the medical community,” said
Tony Petrucci.
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