Dealing with Digestate - How to Valorize the Liquid Digestate by-product from an Anaerobic Digestor (primary source of biomass is human pee) - question from Canada

  • ttmarie
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Dealing with Digestate - How to Valorize the Liquid Digestate by-product from an Anaerobic Digestor (primary source of biomass is human pee) - question from Canada

Hello Everyone,

My name is Antoinette and I'm new to the Forum! Over the past few months I’ve been working to establish an AD facility in Montreal, Canada. My primary source of biomass is human pee, subsequently my biomass is 95% liquid.

My digestate is estimated to be a Nitrogen-based liquid with an N content is 40mg per Liter. Seeing that Nitrogen is a very cheap commodity, at this level of concentration, it is too low for fertilizer use (compared to others on the market) and too high for disposal. Additionally, the agrarian industry is not enthusiastic of liquid fertilizer deriving from human fecal matter so most AD operators here in Quebec choose to treat and dispose of the digestate.

Seeing that I'm approaching my business model with a high level of corporate social responsibility, I want to avoid disposal of the digestate at all costs. I’m trying to find a way to valorize it instead, and was wondering if any of you have come across examples of digestate use other than a soil amendment. I was thinking perhaps pharmaceutical companies, chemical companies or even camping companies.
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  • canaday
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Re: Dealing with Digestate - How to Valorize the Liquid Digestate by-product from an Anaerobic Digestor

Bonjour Antoinette,

Welcome to the Forum.

Please tell us more about your overall project.
--Where does the urine you are treating come from?
--How much urine do you treat?
--Are you in downtown Montreal without agricultural fields anywhere close?
--How do you do Anaerobic Digestion (AD) of urine?
--Do you work within a larger company or are you on your own?
--Why do you mention camping companies?

Here are some initial ideas:
--If you want to extract pharmaceuticals, it seems you would want to do that before AD.
--Growing algae for biodiesel (and other products) might be feasible, especially if you have a rooftop on which to put enclosed, transparent reactors ... and CO2-rich exhaust from motors, heaters or factories to also clean at the same time.
--If you have a source of magnesium, production of potassium-rich Struvite fertilizer may be an option.
--Hydrolysis to produce hydrogen?
--The final effluent could irrigate and fertilize vertical gardens.
--The treatment could vary according the strongly marked seasons that you have there.

Feel free to post messages and documents in French, if that is easier. A large number of the members of this Forum also read French. (I, for example, did my last year in high school as an exchange student at College Saint Anne de la Pocatiere in the Bas de Fleuve of Quebec.) Plus there is the Google Translate option at the bottom of this page to allow users to read posts in whatever language they prefer. (We know this is not perfect, but it should be pretty good between English and French.)

I look forward to hearing more about your project.

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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  • muench
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Re: Dealing with Digestate - How to Valorize the Liquid Digestate by-product from an Anaerobic Digestor

Dear Antoinette,

Chris has already asked you a bunch of questions - the same ones I would have also asked.

I don't understand why you want to put urine through anaerobic digestion (without any other organic matter??). I don't think this would work, as the ammonia concentrations would be too high.

Also you said:
My digestate is estimated to be a Nitrogen-based liquid with an N content is 40mg per Liter.
you might have missed a zero there, it is more like 400 or even 4000 mg/L?

We're always happy to help but first we need to understand your question better.

As you speak of pharmaceutical companies: I was once part of a project in the Netherlands where a company was collecting the urine of pregnant women in their first trimester (at a commercial level) to extract a certain hormone from this urine which was used for fertility treatment for other women. I think they were also able to make said hormone synthetically but at that time the synthetic production was more expensive than extracting it from urine. But it only worked for the urine of women pregnant in their first trimester, as the concentration of that hormone drops off later on in pregnancy. I can look up which hormone it was if interested.


Cheers,
Elisabeth

P.S. Have you also looked here on the forum about more information on urine treatment and reuse options: forum.susana.org/component/kunena/175-ur...euse-or-infiltration

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