View Full Version : Bio-solids as fertilizer?

07-11-2007, 10:10 PM
Just curious to hear what you guys think.

Super fast background on me, I don't run a business yet, probably be next year by the time i'm done learning and purchasing equipment.

I'm currently a wastewater plant operator with the county.

We just installed a system that makes class AA sludge out of the plant waste. It's sterilized and tested and theoretically you could grow vegetables with it.

The particular process we're using is the first of it's kind in the world and basically uses patented chemical processes to treat the sludge.

This company hasn't made any plans to do anything with this "product" as of yet, other than dump it on a farmers field somewhere.

I used to live near Seattle and I know that the City of Tacoma creates a product called "TAGRO" out of their sludge and sells it to the public. http://www.cityoftacoma.org/Page.aspx?nid=306

Is this something you would consider using? There really isn't any odor, it's rather earthy smelling when it's processed and could be mixed with sand and/or mulch. Best of all, there is a steady supply of the stuff and it's virtually free. Lots of possibilities floating around in my head.

I guess i'm just thinking of using or marketing this stuff down the road when things come together and wanted to know what your thoughts were on the subject.

07-12-2007, 05:16 PM
If you can pelletize it, you would have the same product as Milorganite.

07-12-2007, 08:58 PM
Sky, activated bio sludge has literally been around for fifty years.
Started in Milwaukee Wisconsin, hence the name Milorganite and has been moved to many cities since then.
I really like this product and have used it to grow in everything from putting greens on a golf course to residential turf sites.
Regardless of the patented process, the end result is the same unless I am seriously mistaken here.
Post a label or guidelines for more info.

07-12-2007, 10:43 PM
You're completely correct about the end product, the process to achieve the result is irrelevant as you pointed out. I wasn't aware that it was being used commercially so it's interesting to hear that you're familiar with a similar product.

Might be good to give sluggish lawns a quick nitrogen burst, the markup vs. using a traditional fertilizer would be significant.

I checked out the milorganite site and watched their process. They use a more traditional heating process to sterilize the sludge where as we're using a chemical process, which is much lower in energy costs, however it produces a thick cake and not dry little granules, so this stuff would need to be additionally processed to some extent to achieve a similar texture and consistency. None-the-less, very interesting, thanks for the info.

Focal Point Landscapes
07-12-2007, 10:55 PM
I ain't going to use it , no matter how you processed it , particularly on a client's residence. The local water and sewer district here purchased land in an adjacent county to store their processed sludge , then use it for farmers . Caused a huge controversy and the plan was scrapped. Safe or not , people generally cannot overcome the issue of what that stuff used to be ....

07-13-2007, 11:23 PM
Well, it's really all in the marketing.

City of Tacoma's TAGRO product is very well marketed. You can pull up in your pickup and get loaded right at the plant, they mix it with mulch and sand and create several different products out of it. The University of Washington uses it for silviculture experiments and their vegetables have won awards at the Pierce County fair.

If your'e just dumping a big pile of stinky poo somewhere then yes, people aren't going to want it.

I spoke to the company rep about the malorganite, which he was well aware of. While widely successful, he claimed that since they literally cook the stuff, it still smells like crap when the pellets get wet. The chemical process they use leaves the sludge with an earthy smell, not very offensive, so it might be more widely accepted than other products.

07-14-2007, 10:08 AM
Sky, I have a great deal of experience in working with activated bio-sludge cpmpounds.
The N ratio of Milorganite and similar products is only about 5-6% WIN so it does not provide a quick clean up.
The benefit to bio solids is in microbial populations and relative activity (respiration) level as compared with the existent population.
What happens is that as the bio sludge is broken down by the parent microbial population, the microbes become more numerous and respire more. When they respire more they demand more C based nutrients and while consuming these C based nutrients alter the available N to a form more readily available to the host plant for uptake.
Eventually what happens is the bio sludge is completely broken down and over a gradual period of time the turf grass looses it appearance so you have to reapply again.
The trick is that soil types and climatic conditions all interact with microbial species and populations which changes the target time and amount of material that is needed to promote healthy turf. So what works up north may or may not work down south.
And as one additional point, the thermophillic based bio solids do have an ash content to them - a by product from the break down of the bio solid. So aerification is a vital part of the cultural program necessary to extract the most possible from a program utilizing bio solids.

07-14-2007, 10:21 AM
i would like to know what chem they r treating the sludge with and is any left over after it is done?

07-14-2007, 02:22 PM
Dusty, typically not as the thermophillic process basically incinerates any trace metals and solids leaving behind a fairly well weathered cake which is then pelletized.
Actually, as fertilizers are concerned, there is no salt or ammonium based N sources so the osmotic pressure of these types of fertilizers is amazingly minor.
The draw back to these ferts is it takes between 10-15 lbs per 1K square feet depending upon soil structure and type to achieve any measurable (from soil analysis) N inputs.
Also bear in mind the percentage of WIN is very low and since it has no salt or ammonia water uptake isn't the trigger point making this stuff very very easy to use.
Odor really isn't an issue either - this stuff kind of looks like a somewhat powered Cocoa Puff cereal - and it is dusty to use.
About the only achilles heel to this type of fert is mode of action (slow), requires much greater amounts meaning labor is higher to apply yet overall costs remain equivalent, and the potential for ash build up in the soil mandates a rigorous aerification program or laying is a real problem.