Frequently Asked Questions

 on Biosolids

What are biosolids?

Municipal biosolids are the treated, nutrient-rich and organic residual of local wastewater treatment.  Biosolids contain nitrogen, phosphorous and organic matter as well as essential micro-nutrients such as copper, iron, molybdenum and zinc, all of which are important for plant growth and soil fertility. 

Biosolids come from a treatment process that transforms dewatered sewage sludge into a low-pathogen, organic material that helps plants and trees thrive. The material is a benefit to foresters, farmers, and other biosolids users. Pathogens, or harmful bacteria, are decreased by physical and chemical treatment processes that raise the PH level, add heat, and remove water.

What is the difference between biosolids and sewage sludge?

N-Viro’s product is not “sludge”.  It looks like ordinary lime/fertilizer and is applied to fields using fertilizer application equipment. “Sludge” refers to the solids that are settled out at various points in the wastewater treatment process. These solids cannot be removed from the wastewater treatment facilities without further treatment. The term biosolids is used to describe the material after it has been stabilized. The Biosolids Processing Facility (BPF) is able to take unprocessed dewatered wastewater biosolids and produce a treated product that meets or exceeds all applicable guidelines.

Is it safe?

According to the Department of the Environment, its new guidelines regarding biosolids and their use are the most stringent in Canada.  These guidelines are based on the latest biosolid science and research.  In Canada, biosolids must also be federally approved for use.  The United States Environmental Protection Agency has concluded that land application of high-quality biosolids is safe for the environment and humans.

HRM’s Biosolids Processing Facility (BPF), located in the Aerotech Business Park and operated by N-Viro Canada, produces a Class A rated product as defined by Nova Scotia Environment guidelines and regularly attains the Class A standard.  

N-Viro soil also meets the requirements of the United States Environmental Protection Agency’s standard for Exceptional Quality Class A Pathogen Reduction Material.  It also meets the Canadian Food Inspections Agency’s standard as a soil amendment. Rigorous testing by independent laboratories ensures N-Viro soil meets or exceeds these parameters.

The N-Viro process was developed by the Ohio State Medical College and is used in a number of countries other than Canada. All of N-Viro’s test results are posted on its web site at: www.n-viro.ca. 

Does this just take place in Nova Scotia?

The safe, sustainable use of biosolids is something all jurisdictions must deal with, so the use of biosolids on land is common throughout Canada, the United States, and other countries. In terms of the actual processor, N-Viro currently operates similar facilities in Leamington, Sarnia and Niagara Region in Ontario as well as Summerside, PEI. N-Viro markets the product throughout the Maritimes.

Do biosolids smell?

Biosolids may have their own distinctive odour depending on the treatment used on the product.  It can be similar to a regular bag of manure.  Some have a slight musty or ammonia smell, while others have a stronger odour that may be offensive to individuals.  Much of the odour is caused by compounds containing sulphur and ammonia, both of which are plant nutrients. 

Why the noticeably bad smell in the Clayton Park/Rockingham area application?

In 2004, Council approved the $12 million to build a Biosolids facility and secured a contract with N-Viro to operate it and market the product.  Once the plant was a reality, HRM staff sought to look within its own operation to see if there were appropriate uses for the biosolids material which would be acceptable to the public and a positive addition to the environment. 

One opportunity identified in HRM was to support the capital urban forestry project, especially to help with trees in traffic right-of-ways where there is generally poor-grade soil, making it difficult for trees to grow.   HRM staff set out to use a 25/75 blend (25% N-Viro product / 75% topsoil) with biosolids from N-Viro to test its effectiveness in a Clayton Park/Rockingham site.   Those in the vicinity reported an unacceptable smell from the recommended blend of soil and biosolids for this use.

Because of the negative response to that application in terms of odour, HRM Council requested in August that staff prepare a report on issues surrounding the use of biosolids, especially future uses of the product on HRM property.  That report is expected to be presented to Council soon.

Are biosolids bad for the environment?

According to the Provincial Environment Department, biosolids help to protect the environment by keeping treated wastewater sludge from entering the environment by heating and treating it until a useful soil supplement is created. 

N-Viro soil is a beneficial re-use product with soil neutralizing and conditioning properties.  The treatment process destroys the pathogens normally present in raw unprocessed, biosolids.  The biosolids facility has additional environmental benefits. The process lowers greenhouse gas emissions by diverting biosolids from landfills and the former Aerotech stabilization lagoon.

How do biosolids benefit the agriculture sector?

The product is a cost-effective, soil improvement product used by the agricultural community in Nova Scotia.   Because it is sustainable and cost-effective, it helps support the growth of the Nova Scotia economy because of the difference in price for this product versus the more expensive fertilizers.  N-Viro soil also has beneficial uses in the composting process, mixing with other soils to produce topsoil or for gravel pit or mine-site rehabilitation.  Untreated wastewater or sewage on agricultural land is not permitted in Nova Scotia. N-Viro soil is also not used in the production of food crops in Nova Scotia.

The latest provincial guidelines only allow for the highest quality biosolids on agricultural lands.  Agricultural Land is described in the provincial guidelines as land on which food, feed, or fibre crops are grown. This includes range land and/or land used as pasture.

Why not use biosolids to produce energy instead?

Many countries and jurisdictions are looking to use this sustainable and inexpensive product as a source of energy.   

Halifax Water is currently funding studies on the possibility of utilizing biosolids as an energy source.   Results are expected in the near future.

Is the use of biosolids regulated?

In Fall of 2009, the Province of Nova Scotia announced stricter guidelines for the land-application and storage of municipal biosolids. The stricter guidelines were developed from recommendations by an independent committee of citizens, facility managers, wastewater researchers, regulators, and representatives from all levels of government.  The guidelines are based on the latest biosolids science and research.   A copy can be found at:  http://www.gov.ns.ca/nse/water/docs/BiosolidGuidelines.pdf.

The recycling process for biosolids is an environmentally acceptable way to manage the sewage sludge that continues to be generated by municipal treatment facilities.

The Province stated in Spring 2010 that it is working with other jurisdictions across the country to develop national standards and policies for the use of biosolids.

The Nova Scotia Biosolids Science and Advisory Committee gave its report, Biosolids Management in Nova Scotia: Issues and Recommendations, to the Department of Environment in 2009.   The report contains recommendations intended to improve the way biosolids are managed and used.  The Minister of the Environment has said the province is implementing all recommendations, many through the guideline revisions.

How do the new guidelines affect HRM?
The province has said that its renewed guidelines will help protect the environment by helping biosolids users with proper land application and storage of the material. Municipal treatment facilities that make biosolids must follow the guidelines and have approval from the Department of Environment.   All facilities' approvals are to be reviewed to ensure the guidelines are being followed.

The new guidelines will also mean more intensive analysis to test for contaminants such as dioxins, furans, and fire retardants for treatment plants.

What happens to contaminants such as pharmaceuticals and personal care products which flow through our wastewater system?  Are treated biosolids tested for these materials?