Anaerobic Digestion of Manure: There has been a breakthrough in the throughput of manure-fed AD Plants!
A new pre-treatment process development by Ductor™, raises new hope for super-efficient on-farm manure fed biogas plants.
The Problem With Anaerobic Digestion of Manure
Almost all organic materials such as manure are good feedstock materials for biogas production.
Farm manures, from dairy manure, to chicken litter are available in abundance as a feedstock, but until now the AD Plants which process them have all suffered from a huge draw-back.
The reactors have to be very large, because the fermentation process is very slow for these high Nitrogen (high-N) materials, and biogas production is low compared with other lower N feeds.
This means that for on-farm manure anaerobic digestion to be economically viable only very large farms which can provide economy of scale can benefit from these large AD plants.
The Need for a Breakthrough in Manure AD Plant Productivity
Until now the (high-N) reactors have had to be very large, because the fermentation process is very slow for these high Nitrogen (high-N) materials.
A breakthrough in AD process technology is needed to raise the throughput rate, and we know this is possible because every cow on the planet does it far more efficiently than any man made biogas reactor!
The Ductor™ Approach which Resulted in AD Plant Productivity Doubled In Tests
High-N materials hamper biogas production by inhibiting the bacteria in charge of breaking down organic material.
So, Ductor’s process designers said: “What if nitrogen could be separated from feedstock BEFORE biogas production?”
So, they embarked on a research and development project to find a way to do just that.
And, now this is possible, as a new approach to AD Plant process design using an additional fermentation stage to pre-treat feedstock, which has been developed in Finland by Ductor.
This process is known as the Ductor™ fermentation technology, where feedstock is (currently) fermented for about five days to convert organic nitrogen into inorganic one, namely ammonia (NH3).
Ammonia is then processed out from slurry by stripping it out and storing it in liquid form, which can be used as a raw material for fertilizer production. According to Ductor’s website in a trial the ratio of output fertiliser was 115 tons of ammonium sulphate, and 640 tons of solid organic material (fibrous digestate).
The Benefits of Ductor Fermentation Technology
This approach brings three clear benefits:
- Nitrogen is separated from bulk material, which now becomes a phosphorous fertilizer, and if potassium hydroxide is used as the pH controlling agent, a P & K fertilizer.
- Nitrogen no longer hampers the main biogas process, and thus a higher efficiency can be achieved.
- The removal of nitrogen allows new, high N feedstock materials such as poultry manure.
So, it really is possible to select new methods and approaches, and thus recycle the nutrients in a more efficient way.
A great benefit is that additional costs are more than compensated by the benefits brought in as side-effects such as improved biogas yield.
However, subject to ABP Regulations compliance, the separated fertiliser (ammonium sulphate) can become a premium value product sold off-farm as a renewable chemical fertiliser for income, while the fibrous digestate is returned to the farm fields to provide fertiliser for the farm itself.
Furthermore, it is understood that this process technology, which is very much still in its infancy, can be further developed for even better efficiency.
What Ductor Says About Their Fermentation Technology
“The biological method developed and patented by Ductor eliminates the nitrogen dilemma by turning problem waste into profitable recyclable goods. Fraunhofer UMSICHT has been supporting the development of Ductor™ technology for removing ammonia since 2013. “Here, the process principle and the results of the pilot plant in Helsinki were evaluated. From the results so far, it can be concluded that the technology will work,” says Joachim Krassowski, Group Manager of Energy Supply Systems at Fraunhofer UMSICHT. “The process development of DUCTOR, in my opinion, is very professional and has covered all the necessary steps, from laboratory tests to the development of a semi-industrial test facility, up to the first plant on an industrial scale which was erected in Tuorla.” December 2016
“The Ductor® solution has a global market”
“Removing 60% of nitrogen – before biogas fermentation – is a ground-breaking innovation for the biogas industry. This is done by adding one fermentation step, prior to biogas fermentation, and a nitrogen stripping unit. This solution opens up a variety of new possibilities for improving the biogas economy and nutrient recycling. Ductor™’s technology has a global market, since the demand for solutions to improve the profitability of biogas production is tremendous everywhere.”
A “Retro-fitting” Opportunity
At anaerobic-digestion.com we see this process as a retro-fitting opportunity for existing AD plants that are possibly struggling to make a good profit from their current biogas output. Biogas producing businesses in that position may wish to investigate the economic viability of ammonia removal by pre-treatment for their existing biogas plants.
About Ductor™ Corporation:
Ductor™ is a company with a unique portfolio of proprietary and patented technology to improve waste management, energy, and food production. Ductor™ has developed a unique fermentation system that removes more than 60 per cent of nitrogen from organic waste before biogas fermentation. Last year, Ductor™ was awarded a GCCA TOP 10 prize in Taipei.
Visit their website at: www.ductor.com