July 2021

We have a new feature in our eNews: “Dear Dr. Biosolids”

Dr. Biosolids is here to answer all your questions about biosolids research! Canoodling over contaminants of emerging concern? Asking about application rates? Perplexed about PFAS? Stewing on soil science? Northwest Biosolids maintains contracts with university researchers who are here to answer your most vexing questions. This is part of our service to you, our valued members!

Starting this month, you can send in your questions for Dr. Biosolids c/o liz@nwbiosolids.org. In the grand tradition of Dear Abby and Ann Landers, we will assume you’d like to remain anonymous. We will share your question, as well as the answer from one of our researchers, a.k.a. Dr. Biosolids (who will not remain anonymous) in an upcoming eNews.

Northwest Biosolids funds ongoing research projects, but you may not know that a portion of our research contracts is also dedicated to providing funding for researchers to answer inquiries that come in from the public. We want to be sure that our members—YOU!—know that you have that chance to ask your questions. And that our entire biosolids community can benefit from the reply. Please start thinking of your questions now, and send in your questions to liz@northwestbiosolids.org!

*Bing* Oh look! We have a new question in now!

Dr. Biosolids

Dear Dr. Biosolids:

I don’t know what to do – I’m up to my knees in…solid waste. We have 5-10 tons of biosolids that are stinking up our facility, which is hard to get rid of because no one wants smelly biosolids. We do not have a composting facility like other operators, so are there additive options to help with the smell so they are more enticing for folks to take them? How do we get them to smell better?


Something smells rotten in Denmark


Dear Something smells rotten in Denmark,

Nobody likes a stinky pile- I feel your pain.  But for some smell can be taken as a sign of strength.  Go to any farmer who has ever worked with animal manures and they will realize that the smell is an indicator of just how potent your product really is.  With a tiny pile like that – four acres of wheat will take care of your pile in no time.  Those 4 acres are just a speck on a map in Douglas County.

Say however, that you are hosting a pile that tests as a Class A and you are hoping to distribute to people used to growing roses and not grains.  You have the opposite problem of lipstick on a pig.  You have lipstick that smells like a pig and no home rose grower is likely to want any of that near his/her/ their blossoms.  To see what options you have to take the pig away from the lipstick, I consulted with Dan Eberhart, master of the pile at Tagro.  He and I came up with some options for you.

First of all- that stink comes from moisture.  Anaerobic conditions reduce sulfur into very smelly stuff.  There are a range of compounds with reduced sulfur that top the list for nuisance odors.  Dimethyl disulfide is just one example.  Then there is the class of compounds with nitrogen in them that stink. Cadaverine (C5H14N2) is a prime example.  Not too much of a challenge to guess what the odor on that one is like.  Biosolids are chock full of both sulfur and nitrogen- take away the air and those beneficial nutrients turn around to bite you in the butt. 

The key to reducing the odor is to take away the conditions that cause it.  Number one thing to do is to get rid of the moisture.  There are two ways to do this.  You can spread your pile out- it is summer time now and optimal drying weather.  That will likely increase odors initially but they should dissipate pretty quickly.  Hopefully the initial burst of smell won’t result in a work boycott at your plant.  A second option would be to mix a chunky woody material with your cake.  You don’t have to compost to start getting some air flow going through the pile.  A coarse mixing with plenty of coarse wood and maybe even some sawdust will help you out. 

These are the answers that Dan and I came up with.  The real answer is troubleshooting any issues in the treatment process that got you the stinky material in the first place. 


Sally Brown, Ph.D., University of Washington

a.k.a. Dr. Biosolids