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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