Sewage sludge is what remains after wastewater treatment plants have completed their work. North America’s wastewater includes not only urine and feces that goes down toilets but the waste that goes down the drain from households, hospitals, garages, factories.
When the disposal of sewage into waterbodies, resulted in fish deaths, habitat destruction and citizen uproar, the Clean Water Act of 1972 required better treatment and other means of disposal. In the mid-1990s, the treatment industry rebranded the toxic sludge that is the end product of wastewater treatment as “biosolids” and spread it on agricultural lands. Initially, farmers took it as free fertilizer; soon they would have to be paid significant amounts of cash to do so.
According to the EPA, 7 million tons of sewage sludge is applied to US land. Most of this is Class B biosolids, the result of sewage treatment that renders sewage 95% free of pathogenic organisms. (Rare cities, such as Tacoma WA, undertake costly wastewater treatment to produce Class A biosolids, with pathogens reduced “below detectable levels.)
Since wastewater is a mix of household waste, industrial chemicals and storm water, the presence of industrial chemicals and toxins is a more serious issue. Typical biosolid samples contain between 30 to 45 contaminants. Of the heavy metals, the EPA has set limits for only eight, including arsenic and mercury. EPA’s monitoring and oversight of federal regulations regarding wastewater treatment and spreading, moreover, appears to have become increasingly lax.
Thanks to investigative journalists and vigilant citizen groups, however, we have growing body of knowledge about the effects of disposal of the products of North America’s wastewater treatment plants.
“Biosolids Hit the Fan“ An excellent overview of the food safety implications of sludge spreading by Portland journalist Joel Preston Smith.
United Sludge-Free Alliance is a organization whose mission is “to provide information on the issue of sludge”; this includes a Tool Kit with ready-to-use handouts. Because there is no other group nationally tracking sludge issues this, this grassroots group started by Pennsylvania farmers is stepping up. Join them!
Sludge Watch Working Group Led by Canadian Maureen Reilly, issues Sludgewatch Digest with daily updates and succinct comments. A free subscription is highly recommended. Sludgewatch Archives go back to 2002.
“A Critical Review of the U.S. EPA’s Risk Assessment for the LandApplication of Sewage Sludge” . By Jennifer M. J. Matheny. New SolutionsVol 21 (1) 43-56, 2011
Toxic Sludge is Good for You! By John Stauber, Common Courage Press. The wastewater treatment industry’s rebranding of sewage sludge as “biosoilds” is documented in this study by PR Watch of the Center for Media and Democracy.