Monday, July 01, 2019

Let's Make Biogas from Straw - Rika Biogas Bioextrusion® - Anaerobic Diggestion

Why not make biogas from straw! New extrusion process it possible that a good feedstock can be created through the far more rapid development of anaerobic digestion of straw.


Research Sources for the Bioextrusion Process

The Bioextruder can create totally new feedstock options such as straw and desiccated grasses, or increase the biogas yield of traditional substrates such as maize or grass silage.

Depending on the solution required Rika Biogas Technologies can also specify equipment that can increase yields, speed up digestion and remove extraneous materials. These items normally sit in line with the extruder to produce a fully integrated feeding and feedstock processing solution that ultimately reduces your running costs. www.bioextruder.co.uk

Bioextrusion was Originated by LEHMANN

The Process of "Bioextrusion research and development was begun by LEHMANN®"

[Bioextrusion] leads to the formation of new bacteria stains and an improved C/N-ratio, because celluloses and hemicelluloses is decomposed and liberated from the embedding lignin layer. The 5- and 6-times sugar is faster available. Low-molecular and fast transforming substances like alcohol and other compounds develop.

The Fraunhofer institute IKTS in Dresden and LEHMANN Maschinenbau GmbH Jocketa have investigated to to what extent these difficult substrates are suitable for biogas production. via www.lehmann-maschinenbau.de

New insights into the impact of bioextrusion on biomass deconstruction using carbohydrate-binding modules

Lignocellulosic biomass is a sustainable source of renewable substrate to produce low carbon footprint energy and materials. Biomass conversion is usually performed in two steps: a biomass pretreatment for improving cellulose accessibility followed by enzymatic hydrolysis of cellulose. In this study we investigated the efficiency of a bioextrusion pretreatment (extrusion in the presence of cellulase enzyme) for production of reducing sugars from corn crop agricultural residues. Our results demonstrate that bioextrusion increased the reducing sugar conversion yield by at least 94% at high solid/liquid ratio (14%–40%). via www.sciencedirect.com

During the process the substrate is decomposed into its cell structure by a double-screw extruder with pressure with that high temperature and resulting of alternating load and multiple pressure/relaxation cycles in the machine. The biogas yield increases due to a better biochemical-availability and a strong enhanced surface area. The fiber is ideal culture medium of metabolizing bacteria.

This leads to the formation of new bacteria stains and an improved C/N-ratio, because celluloses and hemicelluloses is decomposed and liberated from the embedding lignin layer. The 5- and 6-times sugar is faster available. Low-molecular and fast transforming substances like alcohol and other compounds develop.

The sustainability and efficiency of biogas production is primarily determined by the substrate costs. It is necessary to exploit new substrates and to increase the energetic utilization ratio of the used substrates. Till now, highly lignocellulosic substrates or residues like straw or landscaping residue materials as "not or limited usable for biogas production".

The raw fibre is also degradable by bioextrusion. via www.energy-xprt.com

The transcription text of the video: "Let's Make Biogas from Straw" follows:

Video Transcription

Let's Make Biogas from Straw Not Field Crops.

Around 30 million tonnes of cereal straw are produced in Germany annually.

It has been estimated that 8 to 13 million tonnes of this could be used sustainably for different energetic paths of utilization.

Large quantities of straw are also produced in the UK, and throughout temperate climate regions globally.

Straw is one of the agricultural residues with the largest untapped potential for use as a biomass feed for biogas.

But, so far here has been only limited use of the energy in straw and what has been used has been based on thermal recovery, such as by pelletizing straw for domestic heating.

The disadvantages of this are the extremely large storage capacity needed for the dry material, as well as the high CO2 emissions from transport and processing.

In contrast, the use of straw in anaerobic digestion seems sensible.

The nutrients and organic matter, which was not converted into biogas in the fermentation process, are available again as a high quality digestate after fermentation, with the resulting digestate available to sustain this as a cycle by, its use as a crop fertilizer.

But there is a problem with this. Straw has a very high content of lignocelluloses and a low portion of readily fermentable materials.

During the fermentation process this causes very long digestion times and a low biogas yield.

Also, straw tends to float in the digester, even after being shredded.

Unwanted floating layers can then easily become a mixing problem, again reducing biogas production.

While some digester mixers might be able to cope, the mixing energy used reduces the remaining energy which can be sold.

A Solution to Low Straw Biogas Yields

One German company has devised a solution which they call Bioextrusion®.

The treatment (extrusion) of the straw has 3 beneficial effects:

1 - It reduces the particle size (fibre length) for reduced viscosity and easier mixing.

2 - The lignocellulosic structure is partially destroyed and,

3 - At the same time, the absorptive capacity of the straw increases, and the floating behavior of straw fibers inside the fermenter is much reduced.

After Bioextrusion® the straw is described as spreading almost perfectly in the operating volume of the fermenter.

Straw substrate which is modified by Bioextrusion® is then suitable for wet-fermentation in the standard CSTR process.

On arable farms Bioextrusion® may also be used to raise biogas output from other crop residues such as maize.

Want to know more?

Visit their article about Rika Biogas Technologies at: www.bioextruder.co.uk

Phone: +44 (0)1746 714 704


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