Eliminating Mercury in Sewage Treatment

A city along Lake Michigan is fighting the construction of a waste-treatment plant. The town filed a lawsuit against the local waste-treatment company that wants to dry and burn sludge from half the surrounding county. City officials say they don’t want an eye sore on their lake front and environmentalists are worried about mercury getting into the lake. But the sanitary district says it has a system that will virtually eliminate emissions. As the Great Lakes Radio Consortium’s Annie MacDowell reports, environmentalists say that’s not enough:

Transcript

A city along Lake Michigan is fighting the construction of a waste-treatment plant. The
town filed a lawsuit against the local waste-treatment company that wants to dry and burn
sludge from half the surrounding county. City officials say they don’t want an eye sore on
their lake front and environmentalists are worried about mercury getting into the lake.
But the sanitary district says it has a system that will virtually eliminate emissions. As
the Great Lakes Radio Consortium’s Annie Macdowell reports, environmentalists say
that’s not enough:


After rolling out of bed in the morning, what’s the first thing you do? Do you use the
toilet? Take a shower? Brush your teeth? Probably one or all of the above. And what
happens to that unwanted dirty water? It just vanishes, right? Flushes into oblivion?
Disappears down the drain? Wrong. All that scummy sludge heads straight for your
local waste water treatment plant.


The North Shore Sanitary District along Lake Michigan in northern Illinois receives 187
tons of waste water a day. That adds up to 20 trillion gallons of the stuff a year. And in
among all that waste there are 26 different toxic metals. At this point, North Shore is
trucking the toxic sludge to landfills and dumping it. Brian Jensen is the general manager
of North Shore. He says toxic chemicals aren’t necessarily safe in a landfill because a
landfill liner can leak.


“If in fact, that liner were to leak, and there’s been a history around our country and in
Europe that these liners do leak, when that happens, the environmental liability is
extremely significant.”


With these worries in mind, a couple of years ago Jensen started looking around for a
new way to dispose of the sludge. He says a process called “sludge-drying” was the best
option.


Here’s how the system works: the sludge is pumped into a dryer where most of the water
is sucked out. Then the dried sludge is burned as fuel for the next part of the process –
the melter. The melter burns up the organic part of the sludge at 3000 degrees. That’s
hot enough to melt heavy metals. So after everything else is burned away, what remains
are the toxic metals locked up in a glass matrix that looks a lot like lava. It’s called glass
aggregate. It can be used in concrete where it’s sealed and can no longer pollute water or
soil.


The only toxic metal that doesn’t go into the glass matrix meltdown is mercury. That’s
because in the hot melter, mercury becomes a vapor. Over the course of the year, north
shore gets about 33 pounds of mercury – a third of it comes from fillings in people’s
teeth. The rest is from industry and commercial sources.


People in the area and environmentalists, object to the idea of the plant emitting all that
mercury into the air. That’s because it could further contaminate Lake Michigan which
already is contaminated by mercury from coal-burning power plants. Cameron Davis is
the head of the Lake Michigan Federation. He says mercury is a dangerous neurotoxin.


“You know the MadHatter in Alice in Wonderland? That character was developed
because in the old days, people who made hats actually used mercury in the hat
manufacturing process, and that mercury being around it in the manufacturing of hats,
would cause people, literally, to go insane, to go crazy.”

Davis says Lake Michigan already has a fish advisory because mercury has contaminated
the water so badly. If people eat the fish, especially expectant mothers and children,
there could be serious health effects. Mothers could pass mercury poisoning onto their
infants. Children’s bodies are especially susceptible because they’re developing so fast.
Davis says anyone who cares about the environment is against the construction of any
new source of mercury emissions.


But Brian Jensen says the North Shore sludge incinerator will fix that problem too. The
plans include a filtration system, to catch mercury in the vapor state. The air travels
through carbon canisters and the mercury particles cling to the carbon. The canisters last
for up to 5 years and then the mercury is recycled and reused. The result is something
less than two pounds of mercury emissions a year. Jensen says that’s such a small
amount that today’s scientific instruments can’t detect it in the normal emissions each day.
They’ve tried. And in the end, Jensen says it could very well be that the new North Shore
Plant will emit no mercury at all.


But Cameron Davis says any uncertainty is unacceptable.


“We do want to encourage different ways to be able to get to zero and if we are in fact
getting to zero, then we’ve got a different game here, and that’s important, but we are
talking about zero.”


But Davis doesn’t have any better ideas for getting rid of the sludge. He says North
Shore should continue landfilling for now.


Michael Murray with the National Wildlife Federation’s Great Lakes Office says there is
a better alternative. It’s a process called land application. That’s when sludge is used as
fertilizer for crops.


“There’s a study published on work in France recently where they looked at number of
different options for sewage sludge treatment and they found that land application in
general had the lowest environmental cost, in other words it was the best environmental
option.”


Murray says companies must have a really good pre-treatment program if they’re going
to use land application. That means capping levels of toxic metals before they get into
the sludge.


Brian Jensen at North Shore says he looked into land application and saw too many
problems. He says North Shore already has an award-winning pre-treatment program,
but they still get too many metals to land apply. And he’s heard about problems like e-coli bacteria growths from the fecal matter in the sludge. Beyond that, he says they just
have too much sludge and not enough land to fertilize.


Jensen says he’s confident the judge will not let the lawsuit stop north shore sanitary
district from building the plant. It already has the permits from the Illinois Environmental
Protection Agency. He’s amazed that people are giving north shore such a hard time,
when right next door to where they want to build the waste treatment plant, a coal-burning incinerator emits up to 450 pounds of mercury a year.


“The North Shore Sanitary District is truly people that are concerned about the
environment. And this process, even though it probably, it does, in fact, cost a little more
to own and operate than a landfill, the environmental gains, I’m saying the environmental
gains, not losses, are significantly greater than any other sludge disposal method.”


Jensen says environmentalists should be the first to recognize when a waste water
treatment plant is doing the very best job that’s possible with the most recent technology
available instead of criticizing the effort.


For the Great Lakes Radio Consortium, I’m Annie Macdowell.

Educating Parents About Mercury

Over the years, parents have become more aware of the dangers
in their own homes. So they keep kids away from things like pesticides,
electrical cords, and plastic bags. Still, most people remain unaware of
another threat from a common household item. Ironically, it may be the
first thing you reach for when your child is sick. The Great Lakes Radio
Consortium’s Wendy Nelson reports:

Educating Parents About Mercury

Over the years, parents have become more aware of the dangers in their ownhomes. So they keep kids away from things like pesticides, electricalcords, and plastic bags. Still, most people remain unaware of another threatfrom a common household item. Ironically, it may be the first thing youreach for when your child is sick. The Great Lakes Radio Consortium’s WendyNelson reports: