New Concerns Over Wastewater Sludge

  • Triclosan is an active ingredient in many products claiming antibacterial properties. (Photo by Kinna Ohman)

After sewage is cleaned at a wastewater treatment plant, sludge is left behind. This
sludge is often used on farms as fertilizer. But the wastewater treatment doesn’t get
rid of all the drugs and chemicals we flush down the drain. Kinna Ohman reports
researchers are finding some of these chemicals are affecting wildlife and could be
getting into our food:

Transcript

After sewage is cleaned at a wastewater treatment plant, sludge is left behind. This
sludge is often used on farms as fertilizer. But the wastewater treatment doesn’t get
rid of all the drugs and chemicals we flush down the drain. Kinna Ohman reports
researchers are finding some of these chemicals are affecting wildlife and could be
getting into our food:


Take a tour of any wastewater treatment plant and you’ll soon understand the main
objective: to separate the liquids from the solids. Until the mid 90s, most of these solids,
or sludge, used to go into landfills or were dumped in the ocean. But in 1994 the U.S.
Environmental Protection Agency started a program to promote the use of sludge on farm
fields as fertilizer. The EPA thought this was the perfect solution… turning waste into a
useful product.


But scientists have found something which could turn the EPA program on its head.
Rolf Halden is an assistant professor at the Johns Hopkins Center for Water
and Health. He says sludge contains most of the chemicals we use:


“If you look at municipal sludge, it really is a matrix that reflects the chemical footprint
of our society.”


Halden’s focused on one chemical he’s found in sludge called Triclosan – and
there’s a lot of it out there. It’s in antibacterial soaps, and can even be in our toothpastes,
deodorants, and shampoos. Until recently, most if it was thought to break down. Now,
Halden says they found something different:


“In the work that we have done at Johns Hopkins, we have demonstrated for example that
Triclosan when it enters a wastewater treatment plant is not effectively being degraded
and half of the mass is left over.”


Halden and his colleagues found this leftover mass in sludge. And since half the sludge
produced each year in the US goes to fertilize farm fields, Halden says we might want to
think about our food supply:


“We really create a pipeline of contaminants that are first discharged into the water and
then accumulated in sludge and then applied in agriculture which opens a pathway for the
contamination of the food supply and the further distribution of these chemicals in the
environment.”


At this point, scientists are still studying levels of this chemical. They haven’t even
begun to understand Triclosan’s effects in agriculture. But there’s something they do
know about it.


Researchers found Triclosan can mimic a thyroid hormone in the North American
bullfrog and disrupt its growth. When its tadpoles were exposed to low levels of
this chemical for a short amount of time, their growth into a juvenile frog was impaired.


But this doesn’t sound like that big of a deal… the frog doesn’t die, it just doesn’t grow
properly, right? Keep in mind that this study tracked exposure to Triclosan over four
hours. Halden says by spreading wastewater sludge in agriculture, we could be exposing
wildlife to chemicals like Triclosan for their entire lives.


“When these chemicals are transported into the environment with the agricultural
fertilizer, which is the municipal sludge, then they sit there for in the soil, not only for
seconds but for days and weeks and for months and to even years and in some situations
in sediments, in aquatic sediments, they can sit there for decades and this implies that
organisms are, for their lifespan, exposed to very high levels of these contaminants.
What the outcome of that is really not fully understood right now and requires more research.”


The U.S. Geological Survey has also been looking for chemicals in sludge – or biosolids –
and they’ve found steroids, antihistamines, and antidepressants. Ed Furlong, a research chemist
with the USGS in Denver, Colorado, says they are now studying how these chemicals react in agricultural
fields:


“We’ve identified that many of the compounds are consistently present in biosolids from
across the country. We’re now trying to understand what happens after those biosolids
are applied to the soil.”


The USGS is not the only agency looking at this issue. The Environmental Protection Agency has been conducting its own survey of chemicals like Triclosan in sludge. They say the results of the survey won’t be released until next
summer. Then comes the complicated process of deciding what to do with the survey
results. A decision about whether to stop using sludge with hormone disrupting
chemicals to fertilize farm fields could be years away.


For the Environment Report, I’m Kinna Ohman.

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Using Sewage Sludge on Crops

  • Sludge being spread over a field with a manure spreader. (Photo by D. Seliskar, Halophyte Biotechnology Center, Univ. of Delaware)

The more people inhabit the earth – the more sewage there is. Something has to be done with it. Before chemical fertilizers were invented, farmers used human manure to improve their crops. Some still do. About three million dry tons of treated sewage – called sludge – fertilize sod, pasture land and even food crops every year in the United States. The Great Lakes Radio Consortium’s Amy Tardif looks at what the practice may be doing to the environment:

Transcript

The more people inhabit the earth – the more sewage there is. Something has to be done with it.
Before chemical fertilizers were invented, farmers used human manure to improve their crops.
Some still do. About three million dry tons of treated sewage – called sludge – fertilize sod,
pasture land and even food crops every year in the United States. The Great Lakes Radio
Consortium’s Amy Tardif looks at what the practice may be doing to the environment:


The U.S. Environmental Protection Agency says using treated human waste as fertilizer is the
most environmentally sound way to get rid of it. It used to get dumped in the oceans. The
pollution caused dead zones.


Now, using it on land is becoming controversial. As people move closer to rural areas, they
discover what’s happening. It smells. It might also cause damage. Tommy Drymon insists the
creek near his Florida home has changed because farmers near his house use sludge as fertilizer.


“This was the most beautiful place I’ve ever settled down to. And the creek just looks awful now.
It used to be clear and now it’s just black and mucky all the time.”


Drymon says not only has the color changed – there’s more icky residue on the shore. He rarely
sees otters, deer and other wildlife any more. He definitely stopped swimming in it. Drymon and
his neighbors think the human fertilizer nearby farmers use – known as sewage sludge – is to
blame.


Sludge is made at sewage treatment plants. The water people flush down their toilets gets pretty
clean with today’s methods. That means more of what’s leftover stays pretty dirty. It resembles a
thin pudding or a powder depending on how it’s treated. It can contain viruses, bacteria,
chemicals and cancer-causing heavy metals.


“Now this sewage sludge includes not just human waste, it includes Pine Sol if you clean your
toilet bowl with Pine Sol, or if you do oil painting and you flush the paints down the drain or if
you work in a chemistry lab….”


Eric Giroux is an attorney for Earthjustice. He’s handling a lawsuit for Tommy Drymon and his
neighbors. It claims sewage sludge dumped on farms there is wafting through the air making
them sick and running off into the creek.


There are federal, state and county rules meant to prevent runoff. There are buffer zones from
water bodies and rules to protect groundwater. But sludge is not always applied according to the
rules. And there are things missing from the rules – according to The Cornell Waste
Management Institute. They don’t deal with poisons such as flame retardants, the drugs we take
and toxic chemicals that harm fish and wildlife and inhibit plant growth.


But those who use sludge as fertilizer like it.


“It’s a product that has to have something done with it. And if it’s done properly there are no
problems.”


Dennis Carlton has used the free product on his cow pastures for ten years. He says the calves
raised on those pastures end up weighing more than others. Sludge saves him sixty to 160 dollars
an acre on expensive chemicals.


“It’s cost effective and it does a better job than the commercial fertilizer because it last longer
because of the slow release qualities.”


Sludge contains lots of nitrogen – which is food for plants. It’s organic. Plants absorb it very
slowly. And that’s good.


Since 1997, University of Florida Soil scientist Martin Adjei has compared typical commercial
fertilizer – ammonium nitrate – with sludge. He says his studies show the good stuff in sludge gets
into the plants very nicely, and he says plants don’t seem to absorb the heavy metals.


“We measured lead, barium, cadmium, nickel in the plant. They were all point zero, zero two or
something parts per million in the plant.”


That’s lower than the EPA says it has to be. Adjei says only trace amounts of metals sunk into the
groundwater. He doesn’t know yet whether the metals drift into the soil. But he found too much
of the nutrient phosphorous builds up in the soil when fertilized with sludge year after year. He
admits there are many more tests to be done.


This year the EPA responded to complaints about sludge. It plans to test it for 50 chemicals – far
more than ever before. Geff Grubbs is the EPA’s Director of Science and Technology.


“We’re focusing on a couple of things, one is beginning to ramp up some of the research
investments to strengthen our understanding of some of the processes and nature of the
contaminants that could be present in sludge and what risk they might or might not pose. And we
do have a number of things that are in the works both near and longer term that might lead to
changes in the underlying regulations about what can be in biosolids before they are applied to
land.”


And, the EPA and a few industry groups have created a best practices program for willing
utilities. They pledge to control the odor and dust as well as manage the nutrients in their sludge.
The utilities are then audited by impartial, independent, third parties. There are only 48
municipalities participating nationwide.


For the Great Lakes Radio Consortium, I’m Amy Tardif.

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