Environmental Science & Engineering - www.esemag.com - June 2004
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Ontario seeks comment on its composting guidelines
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Ontario’s Interim Guidelines for the Production
and Use of Aerobic Compost in Ontario was published
as a temporary guideline in 1991 to assist
in the selection and approval of appropriate aerobic
composting methods and the production of quality
compost. The guideline establishes criteria for metals,
pathogens, foreign matter and maturity for a compost product
before it can be used in an unrestricted manner.
The metal criteria in the Ontario guidelines were developed
based on the objective of not significantly affecting
the background soil level when used in an unrestricted
manner. It was noted in the guideline that the compost
quality criteria requirements would be modified as new
and updated information became available.
The Canadian Council of Ministers of the Environment
(CCME) researched and published a national compost
guideline titled "Guidelines for Compost Quality (CCME-
106E March 1996). The CCME guidelines were developed
based on several objectives including the protection of
public health and the environment across the country. It
was also to encourage source separation of Municipal Solid
Waste (MSW) to produce a high quality compost. Other
provincial jurisdictions have adopted the CCME guideline.
The Ontario Ministry of the Environment had proposed
to harmonize with the CCME standard for metals in 1998.
This initiative was part of a comprehensive waste management
regulatory review proposal which was posted for public
comment on the EBR (RA8E0023-1998). At that time,
respondents who commented were supportive of this part
of the proposal. However, the Ministry did not proceed
with the comprehensive waste management proposal
(RA8E0023-2002).
The Ministry’s interim compost guideline used known
upper levels of soil background concentrations to develop
metal criteria for compost. Experience has shown that in
some instances these criteria may be overly restrictive. The
CCME used a combination of soil background concentrations
and concentrations achievable using existing composting
technology for source separated organics to establish
their criteria. The CCME numbers were limited at the
top end by the CCME effects-based soil quality criteria to
protect public health and the environment.
The Ministry is proposing to harmonize its criteria for
metals with that of the CCME guideline. The proposed criteria
for the eleven metals are described below (all values
based on dry weight):
- Arsenic: proposed criteria is 13 mg/kg,
- Cadmium: proposed criteria is 3 mg/kg, (unchanged)
- Chromium: proposed criteria is 210 mg/kg,
- Cobalt: proposed criteria is 34 mg/kg,
- Copper: proposed criteria is 100 mg/kg,
- Lead: proposed criteria is 150 mg/kg, (unchanged)
- Mercury: proposed criteria is 0.8 mg/kg,
- Molybdenum: proposed criteria is 5 mg/kg,
- Nickel: proposed criteria is 62 mg/kg,
- Selenium: proposed criteria is 2 mg/kg, (unchanged)
- Zinc: proposed criteria is 500 mg/kg. (unchanged)
The existing criteria for the same 11 metals are:
- Arsenic: 10 mg/kg,
- Cadmium: 3 mg/kg,
- Chromium: 50 mg/kg,
- Cobalt: 25 mg/kg,
- Copper: 60 mg/kg,
- Lead: 150 mg/kg,
- Mercury: 0.15 mg/kg,
- Molybdenum: 2 mg/kg,
- Nickel: 60 mg/kg,
- Selenium: 2 mg/kg,
- Zinc: 500 mg/kg.
This harmonization of the metal criteria allows for the
production of a high quality compost and enables easier use
and marketing of the end product.
Comments should be directed to: Sr. Program Advisor,
Waste Management Policy Branch, 135 St. Clair Ave. West,
7th Floor, Toronto, Ontario, M4V 1P5, Tel: (416) 314-9404
Fax: (416) 325-4437.
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