Biosolids not affected by SARS virus

    June, 2002
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    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.

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    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.