Environmental Science & Engineering – January 2002

WEAO biosolids report now available

Tony Ho

The Water Environment Association of Ontario has completed the report
entitled: Fate and Significance of Selected Contaminants in Sewage Biosolids
Applied to Agricultural Land Through Literature Review and Consultation with
Stakeholder Groups. Study results which had been presented at conferences
and meetings, are available in the report.

WEAO initiated the study in late 1999 as part of an ongoing effort to update
and improve the agricultural land application of sewage biosolids in Ontario.
Specific objectives of the project were to:

• Review, assess, and summarize information assembled from literature and
  consultation with credible non-government organizations, farming associations,
  experts and regulatory agencies (Stakeholders) regarding the fate and
  significance of contaminants in sewage biosolids after they are applied to
  agricultural lands.


• Use the information to divide specific contaminants in sewage biosolids
  into two groups. Group I contaminants have sufficient credible scientific
  information to assure the public that the current agricultural land application
  program/guidelines are adequate to protect the well-being of soils, crops,
  animals, human health, ground and surface water qualities. Group II
  contaminants do not yet have such information.


• Recommend a long-term study program to complete the information gaps and
  actions that can mitigate any adverse effects that may be caused by the presence
  of specific contaminants in sewage biosolids. Comprehensive Terms of Referencefor the top three studies identified in the long-term study program should be
  provided.


• Disseminate the study findings and recommendations to the Stakeholders and
  municipalities through report(s) and workshop(s).

Major study conclusions and recommendations are summarized as follows:

Heavy metals: the current 11 metals being regulated in the biosolids
guidelines are deemed to be adequate and are classified as Group I. The other
metals silver, antimony, etc., are deemed to be Group II, and more data
collection in biosolids and soil are recommended.

Pathogens: are deemed as Group II. Human health impacts of
pathogens in land-applied sewage biosolids have been studied by many experts.
They all arrived at a similar conclusion that application of biosolids on
agricultural land is safe, provided the guidelines are followed. This included
a three-year epidemiological study done by Ohio University which compared the
health of the people living on farms that received biosolids to those living on
farms that did not receive biosolids. Some members of the public, however, are
still skeptical and remain unconvinced by the evidence. Their concerns arise
from a variety of incidences: the Walkerton E. coli outbreak; microbial
contamination of tile drainage water following animal manure application; and a
perceived inadequate monitoring and control of biosolids application. The study
recommended more studies be carried out to define and build consensus on risk
assessment and management, and to develop and/or evaluate best management
practices to minimize risks.

Trace Organics: which include VOCs, PAHs, pesticides, dioxins and
furans, and LAS surfactants, are deemed to be Group I, due to their low
concentrations in biosolids and/or rapid loss in the soil.

Endocrine Disrupters: Alkylphenol surfactants and their degradation
products including 4-nonyl phenol are deemed to be Group I because these
contaminants biodegraded rapidly in aerobic soil. Estrogenic hormones are
considered as Group II due to lack of data. However, ongoing work at
Agriculture and Agri-Food Canada on concentrations and fate of estrogenic
hormones in land-applied animal manure would be useful to estimate the
significance of hormones in sewage biosolids.

Pharmaceuticals: are considered as Group II due to lack of
information in biosolids. By nature, most pharmaceuticals are designed to be
water-soluble, biodegradable and have short half-lives. The study recommended
that analytical methods for measuring pharmaceuticals in biosolids be developed
and then to be followed by field surveys.

Radionuclides: are deemed as Group II. Ontario sewer use bylaws
prohibit the discharge of radionuclides. Medically used radionuclides that may
be discharged with human wastes are short-lived.

Nitrogen and Phosphorus: are deemed to be Group I due to loading
limits of 135 kg of plant-available nitrogen per hectare per five years.

The study was co-sponsored by the Ontario Ministry of Environment, Ontario
Ministry of Agriculture, Food and Rural Affairs, Environment Canada, City of
Windsor, Regional Municipality of Waterloo, City of Hamilton, Regional
Municipality of Niagara, Regional Municipality of Halton, City of Toronto,
Regional Municipality of Durham, City of Peterborough, City of Ottawa and
Ontario Federation of Agriculture.

Tony Ho and Dan Ionescu, of the Ontario Ministry of Environment, are the
co-chairs of the Technical Steering Committee for the study. The study was
carried out by R.V. Anderson Associates Limited, M.D. Webber Environmental
Consultant and SENES Consultants Limited.

The final report can be downloaded from: www.weao.org.

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