Sewage Sludge Compost: The Sludge Hits the Fan in San Francisco

San Francisco had the audacity to label waste sludge as "organic" and give it away to home gardeners and even school gardens. The city's actions are outrageous, but they serve as a wake-up call.
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When San Francisco, one of the greenest cities in America, offered its residents free compost, many were excited to take it. Few of the gardeners who lined up to receive the free compost at events like last September's Big Blue Bucket Eco-Fair suspected that the 20 tons of free bags labeled "organic biosolids compost" actually contained sewage sludge from nine California counties. On Thursday, March 4, angry San Franciscans returned the toxic sludge to the city, dumping it at Mayor Gavin Newsom's office in protest.

Sewage sludge is the end product of the treatment process for any human waste, hospital waste, industrial waste and -- in San Francisco -- stormwater that goes down the drain. The end goal is treated water (called effluent), which San Francisco dumps into the Pacific Ocean and San Francisco Bay. But the impurities and toxins removed from the water do not go away. With the water removed, the remaining byproduct is a highly concentrated toxic sludge containing anything that went down the drain but did not break down during the treatment process. That usually includes a number of heavy metals, polycyclic aromatic hydrocarbons, pharmaceuticals, steroids, flame-retardants, bacteria (including antibiotic-resistant bacteria), fungi, parasites and viruses.

The EPA only requires treatment plants to kill off any fecal coliforms in the sludge and ensure that nine heavy metals (arsenic, cadmium, chromium, copper, lead, mercury, molybdenum, selenium and zinc) are not present in unacceptable levels. But that only cleans up a tiny fraction of the harmful substances present in the sludge. A recent EPA study of 84 sludge samples from around the country found 27 metals, three pharmaceuticals (Ciprofloxacin, Diphenhydramine and Triclocarban), four anions (nitrates/nitrites, fluoride and water-extractable phosphorus), three steroids (Campesterol, Cholestanol and Coprostanol), and a number of toxic flame-retardants in nearly every single sample tested. Many of the other contaminants tested for showed up in a high percentage of samples as well.

The land application of sewage sludge is actually a national issue, not merely an issue limited to San Francisco or even California. It can be traced back to the Clean Water Act and the subsequent outlawing of dumping sewage sludge into the ocean. The Clean Water Act of 1972 required sewage plants to remove at least 85 percent of pollutants in the waste they received before discharging the resulting effluent. Waste treatment reform advocate Abby Rockefeller points out the irony that the more successful a plant is in removing impurities and toxins from wastewater, the more concentrated and toxic the resulting sludge.

Other options to dispose of the sludge exist, such as dumping into landfills, incineration (releasing pollutants into the air), or gasification to generate methanol for energy (the most environmentally sound and most expensive option), but land application is the cheapest. That is -- it's the cheapest to the dumper, but perhaps not to the dumpee. One year after sludge was spread on an adjacent farm, the cows began to die on the Washington dairy farm of Linda and Raymond Zander. Tests revealed heavy metals in the soil where the sludge was applied and in two neighborhood wells. The casualties were not limited to the cows; Raymond Zander suffered from nickel poisoning and 16 neighboring families reported a range of health problems they believe are linked to the sludge.

So where does this leave San Francisco? According to the EPA, about half of all sewage sludge is applied to farmland as fertilizer. As seen in the McElmurray case, even when sludge is limited to use on fields growing animal feed, the toxins in it can still find their way to the human food supply. Also, Class A biosolids are approved for unrestricted use, meaning they can be applied to farms growing food for humans (although they cannot be applied on land where organic food is grown). EPA expert Hugh Kaufman warns that government regulation for Class A biosolids ignores 99 percent of the pollutants found in it.

In San Francisco, the sludge hit the fan because the city had the audacity to label sludge as "organic" and give it away to home gardeners and even school gardens. The city's actions are outrageous, but they serve as a wake-up call that the entire nation regularly consumes foods grown on fields fertilized with sludge. The so-called beneficial use of our sewage sludge is actually the distribution of sludge into our land, our water and our bodies.

This is an excerpt of a piece originally published on on March 4, 2010. To read the full article, go here.

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