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Sewage biosolids result from municipal wastewater treatment

The treatment of municipal wastewater produces:

Sewage biosolids are then treated by methods such as digestion or addition of lime to reduce the pathogen content and odour-producing potential. Once treated, biosolids can be applied to land in liquid form, or be dewatered and applied as a solid material following provincial requirements.

Sewage biosolids contain nutrients

Biosolids contain nutrients and organic matter that are important to plant growth, such as:

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, (NMA) and the Environmental Protection Act (EPA).

Crop production can be enhanced by biosolids

When applied according to the General Nutrient Management Regulation, sewage biosolids will:

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.

On September 18, 2009 the General Nutrient Management Regulation (O. Reg 267/03), under the Nutrient Management Act, 2002(NMA), was amended to make changes to the regulatory framework for non-agricultural source materials (NASM). The purpose of these changes is to remove duplicate requirements under the NMA and the Environmental Protection Act (EPA) and to introduce quality-based standards for the agricultural land application of NASM. These standards enhance environmental protection by strengthening and clarifying the rules around the beneficial use of this material.

The requirements will take effect in two stages.  Stage 1 changes will take effect immediately upon filing of the regulation and consists of general requirements that establish the framework. The general requirements are needed to transition to the requirements of the new system for managing NASM which take effect at stage 2 on January 1, 2011. Transition periods are also outlined within the regulation to assist in moving from the current framework of approvals to the new requirements.

NASM includes pulp and paper biosolids, other food processing residuals and sewage biosolids. The change from two regulations to one regulation will be complete by January 1, 2016 (when no more Certificates of Approval for land application will exist). 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 have a NASM plan approved by the Ministry of Agriculture, Food and Rural Affairs or a C of A (waste disposal site) under the EPA prior to January 1, 2016.

Municipal wastewater treatment

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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:

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 crops falling over 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:

Metal concentrations in sewage biosolids

Source: 2002 Survey of Municipal Sewage Biosolids Quality (Ontario Ministry of Agriculture, Food and Rural Affairs and the Ministry of the Environment)

Separation Distances

0.30 to 1.0* - separation distance to bedrock varies according to the type of material (i.e. solid or liquid nutrient) and the proposed application rate.  In general liquid nutrients and high application rate require greater separation setback to bedrock.  For more specific distance, refer to section 50 of O.Reg. 267/03.

0.30 to 0.90*- the minimum depth of unsaturated soil at the surface of the application site varies according to the quality of the material and soil type, which may also affect the maximum application rate. For more specific distance, refer to section 48 and 49 of O.Reg. 267/03.

25 to 450* - Setback to dwellings vary according to the odour classification of the material to be land applied and the method of application (surface applied, surface applied and incorporated within 6 or 24 hours, or injected). For more specific information, refer to section 47 of O.Reg. 267/03.

50 to 900* - Setback to residential areas or commercial, community or institutional uses vary according to the odour classification of the material to be land applied and the method of application (surface applied, surface applied and incorporated within 6 or 24 hours, or injected). For more specific information, refer to section 47 of O.Reg. 267/03.

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 is of utmost importance to follow O.Reg 267/03 and use best management practices, which help to maximize benefit by conserving nitrogen, while minimizing odour. The Odour Guide as part of the regulation under the NMA, establishes which category the biosolids will fall into and then O. Reg. 267/03 establishes the setbacks that must be followed for land application of the material. Some discretion is afforded for the director to assign a different odour category to the material. The procedures to do this are set out in the Odour Guide.

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 as part of the NASM plan.

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 are not beneficial to crops, but pose minimal risk to the environment when applied to land in accordance with the Regulation.

The Regulation was 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 Regulation sets out criteria for:

The key to successful sewage biosolids utilization is management, which is a combination of:

Wise management will get the most benefit from the applied biosolids, while minimizing the risk to the environment and the health of people and animals.

A farm-specific NASM plan balances crop requirements, land base, and available nutrients.

Improperly applied, nutrients can be deleterious to soil and water resources. For example:

Over application of nutrients is also a waste of money.

As nutrient sources, sewage biosolids must only be applied in accordance with nutrient management planning principles - meaning that total available nutrients applied must not exceed what the crop can use.

The three commandments of nutrient management planning:

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 some of these residuals to agricultural land is regulated under 267/03; others must be reviewed by the Director who will establish the parameters for testing the material and determining land application restrictions. For more information about unlisted material, 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.

Roles and responsibilities

The success of a biosolids land application program depends on:

Municipality (as generator of the biosolids) have requirements with their C of A:

Hauler/Applicator

Farmer

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