0
points
Is it safe to use biosolids on edibles?

General    Pennsylvania, USA

I read this article from NPR with interest

http://www.npr.org/blogs/thesalt/2013...

and I wondered if anybody would be able to provide me with some further information. The article addresses the use of biosolids in urban gardening and agriculture. The Environmental Protection Agency defines biosolids as:

"nutrient-rich organic materials resulting from the treatment of sewage sludge (the name for the solid, semisolid or liquid untreated residue generated during the treatment of domestic sewage in a treatment facility)"

Given that there is no scientific evidence for a link between the use of biosolids and adverse health effects what exactly are activists claims against its use? I am unfamiliar with this and the article does not specify exactly what the "contaminants" of concern are - could anyone enlighten me? I would also be interested to read any of the original articles which explain why there is no risk to the environment. What research has been done so far?



Posted by: Lindsay McMenemy (2 points) Lindsay McMenemy
Posted: May 14, 2013




Answers

3
points
Because what gets flushed down drains and toilets ends up in treatment plants that produce "biosolids" (a word that replaced "sewer sludge" for obvious reasons), they are incredibly varied. USDA regulates two broad classes of biosolids, Class A and Class B. Class A products, which undergo a higher level of pathogen reduction, are the only biosolids allowed on lawns and home gardens; certain restrictions are imposed on land application of Class B biosolids on commercial farms and forestlands.

The big concerns are pathogens (bacteria, viruses, protozoa, helminths), heavy metals that remain in the biosolids after the basic stabilizing treatments, excess phosphorus loading, and nutrient imbalances.

Odor (not regulated) can be a serious problem in many jurisdictions. Public aversion to the origin of the product itself creates a monumental marketing/acceptance problem for the industry.

The issues around land application of bioslids are hugely complex, even regarding the fertilizer value of a particular biosolid product. Here's a good overview of the topic: http://bit.ly/17qRfEt


Posted by: Peg Boyles (3 points) Peg Boyles
Posted: May 14, 2013


Lindsay McMenemy commented,
Thank you, that is exactly what I was looking for. Also a very informative article which filled in a few blanks from the NPR story. Namely the heavy metals and the low N:P ratio of biosolids that can potentially cause a loading of P in the soil. The issue of metals seems to be purely a matter of regulation but is it possible to balance the N by simultaneous addition of something with a HIGH N:P ratio? I also found the acceptable pathogen densities interesting for Class A. e.g. less than 1 viable helminth ova per 4 gram total solids. How do these values compare with, say, home produced compost containing manure? That classification would include plant parasitic nematodes also. Sorry, I'm thinking out loud here, some more interesting things for me to look up and share :)
about 7 years ago.



3
points
Just to add one more concern in using processed waste, in areas where they may be using reclaimed water you need to know what they mean by reclaimed. It can go thru a couple of processes or 5 or actually just be retention pond water with a little chlorine added. Also, this reclaimed water has nitrogen in it and sometimes salts that can create some problems with your fertilizing program. We don't recommend using this type of water on herbs or vegetables/fruits you would not peel unless the irrigation is from the bottom only. From a personal viewpoint, if I am going to the trouble to grow my own food or food to sell, I would want to know that it is healthy and free of metals, bacteria, etc. I know farmers who use the sludge and have great crops and swear by it; I just prefer to use my simple horse manure and a little mushroom compost and mix it in that sandy Florida "soil."


Posted by: Susan League, UF/IFAS Sumter Program Assistant (1 point) Susan League, UF/IFAS Sumter Program Assistant
Posted: May 14, 2013


Lindsay McMenemy commented,
Interesting, I didn't realize that there was such differences in treatment. Thanks
about 7 years ago.

Susan League, UF/IFAS Sumter Program Assistant commented,
Here's a link to a UF document with FAQs about reclaimed water that you might find interesting. http://edis.ifas.ufl.edu/ss544
about 7 years ago.

Lindsay McMenemy commented,
Thanks Susan!
about 7 years ago.



2
points
Another concern you may want to add to the list is all the medications and chemicals (cleaning products/ pesticide residues and God only knows what else) that are flushed down the drain. Most of these are broken down by the treatment process.Her's an article about these chemicals being found in treated water. http://usatoday30.usatoday.com/news/n... I can only imagine what is left behind in the biosolids if these are still in the treated water.


Posted by: J.D. Archer (31 points) J.D. Archer
Posted: May 14, 2013


Peg Boyles commented,
Good points! (I think you meant to say that most industrial chemicals and pharmaceuticals--both human and veterinary--AREN'T removed or broken down during sewerage treatment.)

While drugs are a becoming a serious problem in drinking water, and some research shows that a few of them show up in biosolids, where plant roots may be able to absorb some of them, the research to date suggests that most pharmaceuticals and industrial chemicals flush out in the water fraction of the sewerage (which is how they end up as a drinking-water concern, since most folks get their water from surface-water sources.

And, depending on what drugs the animals received, you'll get similar problems in animal manures, even composted.

about 7 years ago.



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