Grinding rye silage

[Jim Pace]

i was wondering if anyone has pre ground rye or grass silage before pitting it into the AD solid feeder. Has anyone done the same with top bale straw? Clearly this year has not seen much second rate straw but..

I am wondering if grinding will pay for itself in terms of increased gas yield and reduced mixing time and improved pump-ability. We have also picked up a second hand cavitator following the auction of the equipment from the former Crouchlands biogas plant. We hope this will help us access the fibrous material that passes through the plant and finishes up in the solid fraction of the digestate. The thought is to compare the two systems over a retention period which for us is around 120days depending on how much we recirculate separated material. Our typical feedstock is 70% maize and 30% rye silage. We have pushed the rye to 40% but we then bung up and we see higher pump and stiring costs as well as more frequent failures.

Any thoughts or observations would be welcome. Rye harvesting starts tomorrow.

 

[thesilentone]

i was wondering if anyone has pre ground rye or grass silage before pitting it into the AD solid feeder. Has anyone done the same with top bale straw? Clearly this year has not seen much second rate straw but..

I am wondering if grinding will pay for itself in terms of increased gas yield and reduced mixing time and improved pump-ability. We have also picked up a second hand cavitator following the auction of the equipment from the former Crouchlands biogas plant. We hope this will help us access the fibrous material that passes through the plant and finishes up in the solid fraction of the digestate. The thought is to compare the two systems over a retention period which for us is around 120days depending on how much we recirculate separated material. Our typical feedstock is 70% maize and 30% rye silage. We have pushed the rye to 40% but we then bung up and we see higher pump and stiring costs as well as more frequent failures.

Any thoughts or observations would be welcome. Rye harvesting starts tomorrow.

Great, an interesting practical challenge. Of course grinding/hammer mill/extruder/shredder used on the rye will have a positive impact on all the areas you suggest, plus additional benefits.By opening out the fiber's you will speed up incorporation into the process, increase gas yields and reduce stirring energy and time, so its win win all the way. However the down side is the energy required for whatever equipment you decide to use, and if the cost is outweighed by the benefits.

Straw is a different challenge.

Straw has a high lignin content, and therefore requires a long retention time. So, there are various different ways including mechanical / heat treatment / sonic and cell rupture etc etc. to break down lignin and try to make straw more acceptable as a feed-stock. in volume. Some already claim they have the solution, I would make sure you see conclusive independent research or visit a site using the chosen technology (and ask difficult questions )

Combining both the rye and the straw treatment would save costs, however the straw brings the greater challenge.

 

[Will Wilson]

Interesting!! Like a human with the mechanical (teeth) then the biological (stomach).

What would happen if you soaked the WC silage / straw in water for 24 hours before feeding it? then feeding the water and all - you could pump it in like porridge?

 

[thesilentone]

Interesting!! Like a human with the mechanical (teeth) then the biological (stomach).

What would happen if you soaked the WC silage / straw in water for 24 hours before feeding it? then feeding the water and all - you could pump it in like porridge?

There are many ways to hydrolyze the feed-stocks, however it is all about cost and return on investment.

 

[Valmetal Inc]

I have a Valmetal agrichopper machine grinding silage feedstock before an AD plant in Bedford...the farmer is getting on well with it, machine was delivered in Jan 2018...pm me if you want details or references

 

[sjt01]

The thought is to compare the two systems over a retention period which for us is around 120days depending on how much we recirculate separated material.

How long are your separated solids laying outside between separation and re-feeding to the digester?
When we fed fodder beet rather than energy beet, and had to re-feed separated solids to keep the dry matter % up, the solids started to grow a white mycelium after a few days. I believe this started the lignin breakdown, as we ran for about 9 months without removing any solids from the system. We feed a bit of straw in the cow slurry, which normally forms the bulk of the separated solids, and this was all digested.

 

[thesilentone]

I have a Valmetal agrichopper machine grinding silage feedstock before an AD plant in Bedford...the farmer is getting on well with it, machine was delivered in Jan 2018...pm me if you want details or references

Are you willing to share more detail on here ?

Types of silage, TPH, Retention time, operating temp, Organic Loading rate, uplift in production, energy consumption and or efficiency / operating hours / kwhr etc of the agri-chopper. Cost of maintenance and operation etc

 

[Valmetal Inc]

I don't know an awful lot if I am honest about the technical pieces regarding the AD plant,

But I do know the farmer using grass silage and also whole crop baled as large Hesston's. This is chopped in the agrichopper similar to picture and blown into a tank with a macerator using a pipe kit. The drive can be a 45kW 3 phase motor or tractor of 85 HP in 1000 rpm drive...which ever is suitable ….results are quite good, chop length 25 - 50 mm, throughput between 5 - 8 tph depending on substrate