It was only fifty years ago when thousands of North American cities dumped raw sewage directly into water bodies. A growing body of evidence on the risks of this practice to both human health and the environment led to a surge in legislation on water pollution.
The rapid proliferation of such regulatory controls on wastewater treatment plants (WWTPs) resulted in growing attention on alternative applications for biosolids generated in WTTPs .
A key North American regulatory reform occurred in 1972 when the US amended their Federal Water Pollution Control Act in order to place further restrictions on the discharge of wastewater to waterways whilst encouraging other disposal methods such as land application of biosolids. Biosolids are defined by the US Environmental Protection Agency (EPA) as “the nutrient-rich organic materials resulting from the treatment of sewage sludge.”Further incentives to find alternatives to disposal included additional restrictions on typical options such as legislated Ocean Dumping Bans and increasing costs of incineration or landfill disposal.
The convergence of the above two policy approaches opened the door for WWTPs across North America to explore how biosolids can be treated safely for responsible land application as fertilizers. Over 10 million dry tonnes of biosolids are generated annually at municipal WWTPs in Canada and the US alone. Such quantities offer a compelling reason for WWTPs to evaluate how they can generate additional value streams to their core business. Biosolids treated in accordance with federal and/or state/provincial regulations can be used as fertilizer to enhance plant growth and maintain productive soils in agricultural, residential and even mining site regeneration applications.
In the US, land application of biosolids takes place in all 50 states and are regulated under a federal rule 40 CFR Part 503 (see Plain-English Guide to the Rule). To meet the regulatory requirements, the material has to undergo initial treatment to reduce pathogens and attractiveness to vectors. This rule also sets strict quality standards such as specified limits for metals in biosolids, site restriction, crop harvesting restrictions and monitoring. Additional record keeping and reporting requirements apply to land applied biosolids and biosolids that are surface disposed or incinerated. Class A biosolids, also known as exceptional quality biosolids, contain no detectible levels of pathogens (disease-causing organisms), do not attract vectors and have low levels of metals.
In Canada, the regulations and guidelines for use of biosolids are at the provincial/territorial level rather than the federal level. At a federal level the Canadian Food Inspection Agency (CFIA) has been working in collaboration with provincial governments to ensure comprehensive regulatory oversight and sound management of biosolids.
The emergence of such a regulatory framework across North America has challenged the development of technologies that can provide for safe land application of biosolids. One such example is the Lystek process- an innovative, patented, award-winning biosolids treatment technology that offers many benefits including:
- Registration and recognition as a true fertilizer by the CFIA – with a freeze-thaw stable quality valuable in winter climates.
- A product that meets/exceeds strict quality criteria (US EPA Class A)
- Provides an economic and environmentally responsible recycling option for WWTPs
The controlled land application of biosolids helps provide organic alternatives to fertilizer for agricultural use and helps complete a natural cycle in the environment. Thanks to continuing sound policies across North America which recognize and endorse the safe application of biosolids – the regulatory certainty exists for WWTPs to make cost-effective investments to pursue value-added streams for their sludge. A technology to consider and evaluate when making such investment decisions is the Lystek Process.