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<International Source Book On Environmentally Sound Technologies
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Effluent discharge criteria
In Canada, discharge criteria for federal facilities are set by Environment
Canada, and all other discharge criteria are set by the provinces and
territories. Most permits are determined on a case by case basis, depending on
the quality and type of receiving water and the amount of discharge.
Environmental impact studies are required for all federally funded and regulated
discharges, and may be required by provincial authorities depending on the
volume of the discharge or the sensitivity of the receiving environment.
When discharging to the ocean, until recently preliminary treatment only has
been required, and is still being practiced in many coastal areas. Many plants
discharging to the ocean have primary treatment only, but this is changing. For
example, previously discharges greater than 0.45 ML/d to open marine outfalls
required only primary treatment in the province of British Columbia, but
effective July 15, 1999, a new regulation mandates secondary treatment as a
When discharging to streams and lakes or embayed marine waters higher
effluent standards apply. Typically a minimum effluent quality of 45 mg/L BOD5
and 60 mg/L TSS is required for most non-ocean discharges in Canada. Discharges
to lakes and streams with low dilutions require a more stringent effluent
quality. Health Regulations for small discharges to ground with poor soil
conditions are often less than 10/10 (10 mg/L BOD5
and 10 mg/L TSS) with
stringent fecal coliform criteria (i.e. less than 2.2 MPN/100 mL). Similar
stringent criteria apply for effluent re-use and irrigation applications.
Storm overflows in municipal areas are generally not regulated, unless they
are from an industrial site.
Nutrients and toxicity
Legislation can identify environmentally sensitive zones, which require more
stringent effluent quality standards. This is often based on geological
characteristics such as river valley or lake systems. The Okanagan Valley in
British Columbia is an example of one such zone which has stringent effluent
total phosphorus and total nitrogen requirements for all municipal discharges.
Effluent toxicity is also a common parameter, usually expressed as a
concentration in which no more than fifty percent of the fish die over a
ninety-six hours test period (96hLC50). Often the toxicity is directly related
to the effluent ammonia concentration, and effluent ammonia levels are becoming
more common in permit criteria for this reason. Effluent toxicity can also be
due to high BOD concentrations (eg. primary effluent) which causes oxygen
depletion during the test sufficient to suffocate the fish, as the test protocol
allows for only marginal aeration during the test.
If chlorine is used, permits may specify minimum dosage, retention time and
chlorine residual requirements, as well as sampling, measurement, and
dechlorination requirements. Some provinces have standards for management of
chlorine and sulfur dioxide containers.
In Ontario, if sufficient time downstream of a discharge is provided,
disinfection may not be required. Disinfection from lagoons is generally not
required unless there are sensitive downstream conditions such as a potable
water intake or shellfish beds. Seasonal relaxation of disinfection requirements
may be allowed if the receiving water is not used for recreational, agricultural
or consumptive purposes. Most large population centres disinfect year round, but
some, as in Vancouver, British Columbia, disinfect only in summer when swimming
The provinces of British Columbia, Saskatchewan, Quebec and Prince Edward
Island do not favour the use of chlorine for disinfection. In British Columbia,
dechlorination is mandatory, in other provinces dechlorination requirements are
determined on a case by case basis. There is a growing trend across North
America to disinfect wastewater effluent using ultra-violet radiation, in place
Biosolids are regulated in all provinces in Canada. Agriculture and Agri-Food
Canada (AAFC), the Canadian Council of the Ministers of the Environment (CCME)
and the Standards Council of Canada (SCC) (through the Bureau du Normalization
du Quebec (BNQ)) are involved in development of composting standards for
biosolids. In 1995, the hoped for outcomes of collaboration of the above
- a national Canadian standard for the composting industry (BNQ)
- guidelines for compost (CCME)
- the adoption of new mandatory criteria for compost (AAFC)
Voluntary standardization is coordinated by the SCC, that represents Canada
within the International Standards Organization (ISO). BNQ is one of five
standards writing organizations that is authorized by SCC. Among other things,
BNQ has been given responsibility for soil amendments, organic fertilizers,
fertilization, and treatment of municipal sewage.
CCME guidelines are being developed with four criteria for compost quality
and safety: maturity, foreign matter, trace elements and pathogenic organisms.
Composting is seen as an alternative for management of the organic portion of
municipal waste, since Canada is aiming to divert 50 percent of the waste stream
The Plant Products Division of AAFC administers the Fertilizers Act and
Regulation, and controls compost sold as soil amendment or fertilizer. Soil
amendment or fertilizer must be safe, efficacious and properly labelled, must
not pose significant risk to humans, plants, animals or environment when used
according to directions. Random sampling and analysis of products must meet
established the criteria. The AAFC is currently (1995) working to include a
direct reference to BNQ standard in the Fertilizers Regulation.
Limits are often set by provincial regulatory authorities for effluent
parameters which may be of concern in specific discharges. These are mainly
limits upon metal levels or toxic organic contaminants in industrial or other
special waste discharges.