Sewage Biosolids - Managing Urban Nutrients Responsibly for Crop Production
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Table of Contents
- Sewage biosolids result from municipal wastewater
treatment
- Sewage biosolids contain nutrients
- Crop production can be enhanced by biosolids
- Applying biosolids to agricultural land benefits
urban and rural communities alike
- Municipal wastewater treatment
- Typical sewage biosolids characteristics
- Suitable crops for biosolids land application
- Metal concentrations in sewage biosolids
- Separation distances
- Provincial standards and on-farm management ensure
sewage biosolids are applied safely.
- A farm-specific nutrient management plan balances
crop requirements, land base, and available nutrients.
- Other off-farm generated materials may also benefit
crop production or soil quality.
- Roles and responsibilities
- For more information ...
Sewage biosolids result from municipal wastewater
treatment
The treatment of municipal wastewater produces:
- clean effluent that is discharged to a nearby watercourse
- sewage biosolids, which are high-organic solid, semi-solid, or
liquid materials that are retained for further treatment and processing.
Sewage biosolids are then stabilized by methods such as digestion
or addition of lime to reduce the pathogen content and odour-producing
potential. Once stabilized, biosolids can be applied to land in liquid
form, or be dewatered and applied as a solid material.

Sewage biosolids contain nutrients
Biosolids contain nutrients and organic matter that are important
to plant growth, such as:
- mineral and organic nitrogen, and phosphorus
- micronutrients such as zinc, magnesium, and copper.
They may also contain trace amounts of other elements such as arsenic,
lead, and mercury. Concentrations of these elements in land-applied
sewage biosolids are regulated under the Nutrient Management Act,
2002, and the Environmental Protection Act.
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Crop production can be enhanced by biosolids
When applied according to best management practices, sewage biosolids
will:
- improve soil fertility - offsetting the need for commercial fertilizers
- add organic matter - enhancing soil structure, moisture retention
and permeability, while reducing the potential for wind and water
erosion.
Applying biosolids to agricultural land benefits
urban and rural communities alike
Sewage biosolids have been utilized on agricultural land in Canada,
the United States and Europe for more than 30 years. Applying sewage
biosolids to farmland is an important means of recycling nutrients
in the environment. As such, the process offers economic and environmental
advantages to society at large.
As with spreading manure, applying biosolids may produce odours.
And as with manure, odours can be reduced by timely incorporation
into the soil. When planning biosolids application, it's of utmost
importance to use best management practices, which help to maximize
benefit by conserving nitrogen, while minimizing odour.
The sewage biosolids land application program in Ontario is regulated.
Land application is regulated under Regulation 347 of the Environmental
Protection Act and Regulation 267/03 under the Nutrient Management
Act, 2002. Environmental quality, food safety, and human health issues
and concerns are addressed in both Regulations and supporting land
application publications of the Ontario Ministry of Agriculture, Food
and Rural Affairs and the Ontario Ministry of the Environment. In
addition, each farm site receiving sewage biosolids must be approved
by the Ministry of the Environment.
Municipal wastewater treatment

Text
Equivalent of Diagram
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Typical sewage biosolids characteristics
Aerobic liquid sewage biosolids
Total Solids: 1.6% wet weight
Total Nitrogen: 5.1% dry weight
Fertilizer Equivalent Nitrogen: 0.25 kg/m3 (wet
weight); 2.5 Lbs/1000 gal (wet weight)
Total Phosphorus: 2.7% dry weight
Phosphate Fertilizer Equivalent (as P2O5):
0.4 kg/m3 (wet weight); 4 Lbs/1000 gal (wet weight)
Anaerobic liquid sewage biosolids
Total Solids: 3.0% wet weight
Total Nitrogen: 6.5% dry weight
Fertilizer Equivalent Nitrogen: 1.07kg/m3
(wet weight.); 10.7 Lbs/1000 gal (weight weight)
Total Phosphorus: 3.6% dry weight
Phosphate Fertilizer Equivalent (as P2O5):
1.0 kg/m3 (wet weight); 10 Lbs/1000 gal (wet weight)
Anaerobic semi-solid (dewatered) sewage biosolids
Total Solids: 26% wet weight
Total Nitrogen: 4.0% dry weight
Fertilizer Equivalent Nitrogen: 3.98 kg/m3 (wet
weight); 8.0 Lbs/ton (wet weight)
Total Phosphorus: 2.7% dry weight
Phosphate Fertilizer Equivalent (as P2O5):
6.45 kg/m3 (wet weight); 13 Lbs/ton (wet weight)
Notes:
- Fertilizer equivalent nitrogen is the sum of the inorganic nitrogen
plus 30% of the organic nitrogen applied. It is assumed that no
nitrogen is lost during application.
- Phosphate Fertilizer equivalent assumes 40% phosphorus availability
in the year of application.
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Suitable crops for biosolids land application
Field corn, hay, haylage, pasture, and commercial sod
These crops are well-suited to using nitrogen supplied by biosolids.
Nutrients such as nitrogen should be applied within crop recommendations.
Cereals
Nitrogen management is critical to avoid over application that may
result in the crop lodging (falling down) before harvest.
Perennial legumes and soybeans
Soybeans and hay crops containing more than one-half legumes do not
require added nitrogen but will use added nitrogen rather than fix
nitrogen from the atmosphere. Biosolids that supply
phosphorus and/or organic matter can be of benefit to these crops.
Some materials may cause management concerns. For example, viable
tomato seeds if present in sewage biosolids can
pose a weed problem in a soybean crop
Tree Fruits and Grapes
Some biosolids may be applied in late fall. However, as is the case
for other crops, nitrogen management is critical to avoid over or
under application that may cause poor fruit quality, delayed hardening
of trees or vines, or winter injury.
Notes:
- The maximum application rate per hectare for sewage biosolids
must not exceed the maximum rate specified in the site Certificate
of Approval or as determined by the Nutrient Management Plan, whichever
is most restrictive.
- Nitrogen application rates for individual crops should not exceed
recommended rates. Refer to Ontario Ministry of Agriculture, Food
and Rural Affairs Publications 811 - Agronomy Guide for Field
Crops, 360 - Fruit Production Recommendations, and 363
- Vegetable Production Recommendations, for recommended nutrient
application rates.
- The Ontario Ministry of Agriculture, Food and Rural Affairs nutrient
management computer program, NMAN, can be used for the determination
of suitable application rates.
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Metal concentrations in sewage biosolids
| Metal |
Maximum Concentration
(mg/kg solids) |
Typcial Concentration
(mg/kg solids) |
Arsenic
|
170 |
4.3 |
| Cadmium |
34 |
3.4 |
| Cobalt |
340 |
6.5 |
| Chromium |
2800 |
80 |
| Copper |
1700 |
550 |
| Mercury |
11 |
1.4 |
| Molybdenum |
94 |
6.5 |
| Nickel |
420 |
12 |
| Lead |
1100 |
48 |
| Selenium |
34 |
2.7 |
| Zinc |
4200 |
506 |
Source: 2002 Survey of Municipal Sewage Biosolids Quality (Ontario
Ministry of Agriculture, Food and Rural Affairs and the Ministry of
the Environment)
Separation Distances
| Feature |
Distance (m) |
| Bedrock |
1.5 |
| Drilled well (> 15m depth) |
15 |
| Dug well |
90 |
| Residence |
90/25* |
| Residential area |
450/50* |
90/25* - Residence: 90m if surface applied or 25m if injected or
incorporated within 6 hours.
450/50* - Residential Area: 450m if surface applied or 50m if injected
or incorporated within 6 hours.
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Watercourses
Regulation 267/03 under the Nutrient Management Act, 2002, requires
a minimum 20m separation distance between the top of the nearest bank
of a surface watercourse and the area of application of municipal
sewage biosolids. Greater separation distances may be required depending
on the soil type, the slope of the land and the application method
used in the area near the watercourse. Separation distances are determined
on a case by case basis.

Provincial standards and on-farm management ensure
sewage biosolids are applied safely.
Municipal wastewater treatment plants receive raw sewage from residential,
industrial, and commercial sources. Bylaws regarding municipal sewer-use
do much to control the quality of the raw sewage received at sewage
treatment plants. However, treated biosolids may still contain some
chemicals that aren't beneficial to crops, but pose minimal risk to
the environment when applied to land in accordance with the Regulations.

The Regulations were developed to ensure that any biosolids being
used are of benefit to crops, and are applied to land so as not to
degrade the natural environment or pose harm to human or animal health.
The Regulations set out criteria for:
- concentrations of 11 elements of concern
- amount, method and timing of application
- separation distances from sensitive areas
- suitable soil types and topography.
The key to successful sewage biosolids utilization is management,
which is a combination of:
- proper application methods
- best management practices
- nutrient management planning.
Wise management will get the most benefit from the applied biosolids,
while protecting the environment and the health of people and animals.

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A farm-specific nutrient management plan balances
crop requirements, land base, and available nutrients.
Improperly applied, nutrients can be deleterious to soil and water
resources. For example:
- excessive nutrient applications can pollute surface and ground
water
- nitrate nitrogen is very dynamic, and excessive soil nitrate
at the end of the growing season can leach into ground water, posing
a risk to human and animal health
- phosphorus binds to soil, and can move with eroded soil to rivers
and lakes, degrading water quality and harming fish and wildlife
habitat.
Over application of nutrients is also a waste of money.
As nutrient sources, sewage biosolids should only be applied in accordance
with nutrient management planning principles - meaning that total
available nutrients applied should not exceed what the crop can use.
The three commandments of nutrient management planning:
- Know what you have.
- Know what you need.
- Know how much you are applying.
Other off-farm generated materials may also benefit
crop production or soil quality.
Some industrial processes produce organic and inorganic residuals
that may benefit crop production, such as food processing by-products
and paper mill biosolids.
As with sewage biosolids, application of these residuals to land
must be in accordance with the Regulations. In addition, these residuals
may be subject to a more rigorous review by the Biosolids Utilization
Committee (BUC). For more information about BUC, or land application
of materials other than sewage biosolids, contact the nearest office
of the Ontario Ministry of the Environment or the Ontario Ministry
of Agriculture, Food and Rural Affairs.
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Roles and responsibilities
The success of a biosolids land application program depends on:
- communication
- management
- all parties being aware of their responsibilities.
Municipality (as generator of the biosolids)
- must keep records of:
- biosolids quality
- location of all application sites
- volumes applied to each site
- is also responsible for:
- ensuring land-applied biosolids meet the criteria in the
Regulations
- providing alternative destinations if biosolids don't meet
the criteria or can't be applied due
to weather or field conditions
- preparing a Nutrient Management Strategy
Hauler/Applicator
- is responsible for:
- uniform land application that does not exceed the maximum
application rate
- timely application that is mutually beneficial for the hauler
and the farmer
- must provide the farmer with a report indicating the fertilizer
equivalent values of the land-applied biosolids
- this is essential for the farmer to make sound nutrient management
decisions

Farmer
- has the right to:
- request flexibility in the land application program
- stop or refuse biosolids application at any time
- is responsible for:
- ensuring that biosolids are land-applied at times that are
beneficial for crop production, but not disruptive to normal
farming practices
- ensuring that all waiting periods (as outlined in the Regulations)
between biosolids application and harvesting or grazing are
observed
- utilizing best management practices in order to optimize
the benefit and minimize the risk of sewage biosolids land application
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For more information
- For more information or to obtain a ministry publication call
the Ontario Ministry of Agriculture, Food and Rural Affairs,
Agricultural Information Contact Centre at 1-888-466-2372 from within
Ontario.
- Email your requests to products.omafra@ontario.ca
or visit the OMAFRA website at www.omafra.gov.on.ca.
Orders can be faxed to (519) 826-3633 or mailed to ServiceOntario,
1 Stone Road West, Guelph, Ontario, N1G 4Y2
- Call the OMAFRA nutrient management line at 1-866-242-4460 or
email: nman.omafra@ontario.ca
- Contact the nearest ServiceOntario centre or office of
the Ministry of the Environment
Additional OMAFRA Resources
- Land Application of Sewage Biosolids for Crop Production
Factsheet, Order No. 00-023
- Agronomy Guide for Field Crops, Publication 811
- Soil Fertility Handbook, Publication 611
- Best Management Practices books
- Nutrient Management BMP 05
- Soil Management BMP 06
- Water Management BMP 07
- Nutrient Management Planning BMP 14

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For more information:
Toll Free: 1-866-242-4460
E-mail: nman.omafra@ontario.ca
|