It is estimated that approximately half of treated sewage sludge – about seven million dry tons per year – is applied to farm fields as fertilizer. Also known as "biosolids," it is often provided to farmers for free. While it may be an environmentally sound example of recycling, in many cases it’s merely relocating pathogens rather than disposing of them.
The Real Dirt on Sewage Sludge
By Wendy Priesnitz - Natural Life's editor and author of twelve books.
This article won an Outstanding Media Contribution Award from the Recycling Council of Ontario.
Hold your nose! Waste from households and industries treated at a sewage plant may be spread on a farmer's field near you. Unfortunately, it may contain heavy metals and other nasty surprises that could end up on your dinner plate.
 |
| Photo US Fish and Wildlife Service |
The safe disposal of hazardous waste has been a challenge for both industry and governments for decades. Under increasing assault by environmental groups for dumping waste into landfills, oceans, rivers and lakes, or burning it in incinerators, corporations and governments seem to have agreed upon a new solution.
They rename the waste as fertilizer or dust suppressant and spread it on farmers’ fields and country roads. The code word for this practice is “beneficial use”. While it may be an environmentally sound example of recycling, in many cases it’s merely relocating pathogens rather than disposing of them.
Although many different industries are “recycling” their toxic waste in this manner, one of the most controversial substances is sewage sludge, which is widely used as a soil amendment by farmers in both the United States and Canada.
Sewage Sludge By Any Other Name
Sludge is the mud-like material that remains after treatment of the wastes that flow into local sewage treatment plants. In the U.S., it is estimated that approximately half of treated sewage sludge – about seven million dry tons per year – is applied to farm fields as fertilizer. In many cases, it is provided to farmers for free.
If human wastes were the only thing entering the sewage treatment plants, then sewage sludge would be a relatively safe, nutrient-rich fertilizer that could be safely used in this manner. However, sewage treatment plants also inevitably receive industrial and household toxic wastes.
In a November, 1990 edition of the United States Federal Register, the Environmental Protection Agency (EPA) had this to say of sewage sludge:
“Typically, these constituents may include volatiles, organic solids, nutrients, disease-causing pathogenic organisms (bacteria, viruses, etc.), heavy metals and inorganic ions, and toxic organic chemicals from industrial wastes, household chemicals and pesticides.”
In fact, there are thousands of substances that can be found in typical sewage sludge, including any of the 100,000 or so chemicals produced and used in industrialized nations, many of which illegally end up in the sewers. Anything that is dumped into a sewer – and that is removed from water by the treatment process – becomes sludge.
Footage shows huge flames erupting from methane gas bubbling to the surface of the Condamine River, a result of ongoing coal seam gas mining in the region, some locals say.
