[Digestion] Digestate as fertilizer.

Randy Mott randymott at ceeres.eu
Wed Jun 29 01:05:04 CDT 2011


Okay. My nickname is the Gordon Gecko of biogas: cost per ton? Value of
separate constituents per ton? 

 

Randy Mott

CEERES

 

From: digestion-bounces at lists.bioenergylists.org
[mailto:digestion-bounces at lists.bioenergylists.org] On Behalf Of Peter
Allison
Sent: Wednesday, June 29, 2011 4:31 AM
To: digestion
Subject: Re: [Digestion] Digestate as fertilizer.

 

Hi All,

With regard to utilizing digestate as a crop fertilizer, it is often stated
the slurry is spread on fields with the inherent problem of biological
toxicity and crusting of surface applications.

I believe this process is an incomplete and basically a cheap and nasty
means of disposing a potentially valuable resource.

The addition of a 1.5% potassium hydroxide solution of  to the spent
digestate enables a disassociation of the solid fraction from the colloidal
material. When the un-reacted and fibrous remains are filtered from the
treated mix and the resultant fluid is allowed to settle, colloidal
concentrate or fulvic acid will be found in the top fraction, humic acid in
the lower portion and carbon rich nutrient at the bottom. 

The increased pH also enables a stabilization of biological activity within
the fluids until dilution with water.

These fractions are the most valuable components of the AD process. The
bio-gas is a bonus.

The fulvic acid is a supreme foliar fertilizer, the humic acid is best
suited to soil applications and the carbon mud is an excellent binder for a
wide range of solid crop fertilizer inclusions such as rock-dust, blood and
bone, etc, before pelletizing for broadcast operations.

We are desperately looking for sustainable solutions to chemical based crop
fertilizers. Most agriculturalists are aware of the folly of NPK reliance. 

AD, like the composting of organic waste materials provides all of the
nutritional requirements for every form of plant-life.

Recycling of crop nutrients via AD has the ability to negate the detrimental
effects of chemical agriculture, repair degraded soils, help resolve
salinity problems, increase nutritional food values of crops, increase soil
moisture holding capacity and put an end to the contamination of precious
waterways. 

Simply dumping spent digestate on fields is a lazy and mindless means for
disposal.

Don't waste waste.

Regards,

Peter.  

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