Sludge Watch ==> AP Story on Sludge - Sludge Makeup Hard to Know - thallium, radiation, PCB etc

[Maureen Reilly]

Photo and text:

Thomas A. Burke, professor at The Johns Hopkins School of Public Health in 
Baltimore, Md., Thursday, July 19, 2007. The idea that sludge, the leftover 
semisolid wastes filtered from water pollution at 16,500 treatment plants, 
can be turned into something harmless, even if swallowed, has been a tenet 
of federal policy for three decades. A series of reports by the EPA's 
inspector general and the National Academy of Sciences between 1996 and 2002 
faulted the adequacy of the science behind the EPA's 1993 regulations on 
sludge. The chairman of the 2002 academy panel, Thomas Burke, a professor at 
the Johns Hopkins Bloomberg School of Public Health, says epidemiological 
studies have never been done to show whether spreading sludge on land is 
safe.(AP Photo/Kathleen Lange

...................................

Sludge Makeup Hard to Know
By KEVIN S. VINEYS – 4 hours ago

ARLINGTON, Va. (AP) — Every day Larry Slattery goes to work, the 
Environmental Protection Agency asks him to do the impossible.

Not only does Arlington County's water pollution control chief have to 
separate sewage and other pollutants from the wastewater gushing into the 
treatment plant. He also must turn the leftover sludge into a fertilizer and 
eliminate any risks of spreading illness when it is used.

"Now, it's not possible to totally eliminate everything," he said.

No one can say exactly what is in sludge. It's a constantly changing brew of 
human, commercial, hospital and industrial wastes. The primary organic 
ingredient is human excrement, which proponents say makes sludge a useful 
fertilizer.

Critics worry about the metals and pathogens that remain.

"These sludges are the worst media you can imagine because they will 
generate antibiotic resistant organisms," said Murray McBride, director of 
the Cornell Waste Management Institute.

What's not monitored raises even bigger concerns: perhaps tens of thousands 
of industrial chemicals, drugs, personal care products, flame retardants and 
other byproducts of modern civilization — virtually anything flushed down a 
toilet or poured into a drain.

All can end up being spread on land used to grow food or animal feed, or 
used on parks and ball fields, or sold to consumers as garden fertilizer.

"There are lots of things that make it through the treatment plants," said 
Thomas Burke, an epidemiologist at the Johns Hopkins Bloomberg School of 
Public Health in Baltimore. He headed the National Academy of Science's last 
study of sludge.

Some of the more alarming things found in treated sludge used as fertilizer 
include:

_PCBs. Last year, Milwaukee sludge tainted with polychlorinated biphenyls 
was spread on parks and athletic fields. Officials believe the PCBs, a 
cancer-causing chemical banned in 1977, were illegally dumped or stirred up 
during sewer maintenance.

_Thallium. Dairy farmers in Georgia say their herds were poisoned by sludge 
in the 1990s and that tests they conducted on milk bound for store shelves 
showed elevated levels of thallium, which was once used as rat poison.

_Radiation. For years, Plutonium-239 was discharged from the Lawrence 
Livermore National Laboratory to the local treatment plant in California, 
which converted the sludge to fertilizer that was distributed to residents 
and spread on parkland. A federal probe determined in 2003 that although 
radiation levels in the area where sludge was used were elevated, there was 
no threat to human health. A 1994 General Accounting Office report listed 
nine treatment plants where radioactive contamination had been found.

When water first enters a treatment plant, wood, rocks, plastics and other 
big objects are screened out. What's left goes into large tanks where the 
heavy solids settle to the bottom. Bacteria and other microorganisms eat the 
organic pollutants. Chlorine is added to the water to kill these bugs; 
sodium bisulfite removes the chlorine.

The cleansed water is then discharged into local waterways.

The remaining pollutants are pumped to tanks where other bugs digest some of 
them. The sludge is then spun to remove excess water. It may be mixed with 
caustic lime or may be heat-treated to kill disease-causing microorganisms.

EPA rules for reducing these pathogens set up a two-part system for 
classifying sludge:

_Class A, heated and composted to kill pathogens, is considered safe for 
direct contact immediately after it is made. Varieties are sold to consumers 
under brand names such as Milorganite and Orgro. But fecal coliform and 
salmonella regrowth can occur.

_Class B, not treated as much, is still considered safe for use as a 
fertilizer, but there are restrictions on how soon people and livestock can 
come in contact with it, as well as on its use for growing crops for human 
consumption.

Treatment plant officials rely on old-fashioned chemistry to tell them if 
something toxic has made it into the plant: often the smell in the air will 
change or the bacteria digesting the sewage will die off when contaminated 
by hazardous chemicals.

"Most of what's coming in here is pure water," Slattery said. "But that 
little bit of solids that's in there is a big deal."


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