Waste Not Want Not
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Sludge Happens

Recycling sewage into fertilizer might be making us sick. Why doesn't the EPA give a crap?

The official response to new discoveries of contaminated sludge remains tepid. In May 2007, the EPA learned that sludge had contaminated as many as 5,000 acres of grazing land about 25 miles from Kimbrough's Alabama ranch with perfluorooctanoic acid (PFOA), a probable carcinogen used in Teflon. The chemical was traced back to a local manufacturer that had dumped contaminated wastewater straight into the sewer. The case prompted the EPA to issue its first-ever advisory on PFOA in drinking water, but it did not ban the dumping of the chemical into sewers or require sludge to be tested for it. Even though the exceedingly high PFOA concentrations in the Lawrence County fields could pose a health threat to animals or humans, as of press time, the Department of Agriculture hadn't tested local cattle for the chemical.

Why does the EPA remain so unconcerned about sludge? Much of it is expediency, maintains Stauber. "You had some individuals who decided that 'out of sight, out of mind' would be the easiest way to handle this massive toxic disposal problem," he says.

Suzanne Rudzinski, who oversees biosolids in the EPA's Office of Water, says the agency's approach has been prudent and balanced. "There's always somebody, no matter who, that doesn't like what the EPA is doing," she says. She grants that the pervasiveness of flame retardants and other chemicals in sludge is a concern, but would like to see more research before recommending whether to regulate them. "I think we agree that there's a lot more that we could learn," she says, "and that's what we're trying to do."

But Chris Nidel, the attorney for two Virginia families that recently resolved a lawsuit with Synagro, says the EPA's wait-and-see stance is nothing but wishful thinking: "This is an experiment—with the initial results being negative—that we are going to continue ad nauseam until we have a regulatory agency that has a backbone."

 

MIGHT THERE BE a better way to get rid of sludge? Perhaps, thanks to this nifty fact: A single American's daily sludge output can generate enough power to light a 60-watt bulb for more than nine hours a day. Sludge is rich in methane, the main component of natural gas. That means that the wastewater sector, which uses about 1 percent of the nation's electricity, could power itself with sludge and possibly have wattage to spare.

So far, however, fewer than 10 percent of the nation's 6,000 public wastewater plants have anaerobic digesters that can extract methane from sludge; of those, just 20 percent burn the gas for energy. However, other promising projects are under way. Flint, Michigan, is one of several cities worldwide to fuel buses with gas from sludge. Last summer, Los Angeles began injecting sludge into a mile-deep well, where pressure and heat are expected to release enough methane to power 1,000 homes.

Sludge power is only a partial solution. At best, methane removal cuts sludge's volume in half. Currently, leftover sludge is often incinerated, releasing heavy metals into the air and packing landfills with enough ash each year to fill more than 3,100 dump trucks. New high-efficiency poop-to-power plants can minimize those impacts. Using high-temperature or low-oxygen reactions, they covert sludge into a synthetic gas or oil, or a char similar to barbecue briquettes. The process can produce twice as much energy as it consumes, says Brian Dooley, a spokesman for Atlanta-based EnerTech, which built the first commercial plant of its kind in Southern California last year. The plant converts sludge from about a third of Los Angeles and Orange counties into a char that replaces coal at a local cement kiln; its ash is mixed into the cement. Such efforts, which reduce landfilling and emissions, have earned praise from some anti-sludge groups. Caroline Snyder, the founder of Citizens for Sludge-Free Land, calls it a "win-win situation."

The EPA says sludge power holds promise, but it's not quite ready to quit pushing sludge as a wonder fertilizer. This hasn't deterred the sewage industry, which sees a chance to get into the renewable energy business and put a stop to the stream of health complaints and costly lawsuits. "After almost 40 years of working in biosolids," a WERF official wrote in a recent newsletter, "I never thought I'd say this: it is an exciting time for sludge!"

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