Finding a safe home for poultry manure

Finding a safe home for poultry manure 1
Poultry manure on field

A recent article in the website entitled After millions spent, solution for excess [poultry] manure still elusive, looks at the level of success of a number of projects on how to deal with poultry manure. 

The projects were funded by the Maryland Department of Agriculture’s Animal Waste Technology Fund. This Fund “provides incentives to companies that demonstrate new technologies on farms and provide alternative strategies for managing animal manure. These technologies generate energy from animal manure, reduce on-farm waste streams, and repurpose manure by creating marketable fertilizer and other products and by-product”. 

Since 2014 the Fund has provided $6 million to 8 projects to develop uses of poultry nature other than spreading to fields. Maryland produces c. 400,000 tons (360,000 tonnes) of poultry manure each year, resulting in potential contamination of the Chesapeake Bay.  So far, no project has proven to be a sliver bullet to solve the poultry manure problem.

[The 2019 request for proposals for the Fund closed on 28 December 2018.]

How much poultry manure is produced in the USA?

Coincidentally, I have just been re-reading an excellent 2017 article by Craig Coker of Coker Consulting, published in my bedside-reading website Biocycle. The article considered the use of the 550 million tons (506 million tonnes) of poultry manure produced annually in the U.S. by 10.7 billion broilers, layers and turkeys. Craig’s two-part article looks at how poultry manure can be anaerobically digested to produce electricity. 

Problems with anaerobically digesting poultry manure

A great deal of research and many trials have been carried out on how to successfully anaerobically digest nitrogen-rich poultry manure. This high level of nitrogen produces problems with the digestion process and therefore poultry manure is commonly added as only a minor component of the feedstock for the digesters. 

However, one facility has been designed specifically to use only poultry manure as feedstock. This is the £23 million ($30 million) Stream Bioenergy facility at Ballymena in Northern Ireland that opened in 2017 and uses the Danish company Xergi as technology supplier. Xergi is owned by Nature Energy. The facility uses the Nix (Nitrogen Extraction) pre-treatment system to get around the high-nitrogen problem. 

A video of the facility in operation is available. 

Using poultry manure to grow microalgae

I not only  work in anaerobic digestion and commercial-scale composting but also in the cultivation and use of microalgae. I am always encouraged when these technologies come together.

It is known that an extract of the digestate produced by the anaerobic digestion of poultry manure can be used to grow microalgae such as Chlorella, and Scenedesmus

The University of Maryland is working with Baltimore-based HY-TEK Bio to go a step further by using an extract of fresh poultry manure to grow microalgae. A summary of the project is available.

The study used a strain of the microalga Scenedesmus obliquus called HTB1 that was isolated from the Chesapeake Bay.  The strain has a tolerance to high levels of carbon dioxide. HY-TEK bio are focused on using HTB1 to mitigate the high levels of carbon dioxide in the flue gas produce by the gas engines at anaerobic digestion facilities and elsewhere.

The growth of HTB1 in a standard microalgal nutrient solution (BG11) was compared to growth in a number of poultry manure extracts. Growth levels in media containing poultry manure extract exceeded that in BG11. The project concluded that poultry extracts could be used as a cost-effective fertiliser for the large-scale production of microalgae.

The commerical cultivation of microalgae to produce animal feed, fish feed, protein, pharmaceuticals and nutraceuticals is increasing rapidly in many countries.  The farming of poultry is also increasing and – as nature demands – so is the production of poultry manure.

I think there is a great opportunity for these two developments to travel hand in hand, with extracted poultry manure being used as a cost-effective source of nutrients for microalgal growth at commercial levels.

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