Just to make things clear, the portagester system is not designed for large-scale cattle dung processing. It was originally designed to separate cattle dung from straw, as straw is often used for cattle bedding in the UK. The original system was used on a farm that had about 300 cattle. Being a "portagester", i.e. portable on wheels, it is limited in how much it can process at one time.
When Burdens took over Bioplex Ltd (who developed the portagester), the idea was to use the system to separate the fibrous part of food from the digestible part. Again, the aim is to use it for relatively small-scale operations, as opposed to the large-scale systems that are being installed in UK and the rest of Europe. Local processing saves the financial and energy costs of transporting wastes. The food waste that is used in the existing commercial food waste digesters in the UK can be transported from as far as 80 miles away, which rather negates the carbon saved from using a renewable source of energy to generate electricity.
The Bioplex process is being commercialized under a new company, Oak Bioenergy Ltd, which is still being set up. We hope to have a system ready for the market (initially farms in the UK) within six months.
The portagester acts as a pre-digester and removes the digestible matter as liquid and leaves the solids behind. The liquid contains the VFAs, which the anaerobes use to generate biogas. Dewatering the dung, as Rex suggests, would remove most of the biogas potential of the dung. The solids from the portagester, after the liquid is removed, are used as a fertilizer via aerobic processing (i.e. composting).
There was a system set up in the UK, Holsworthy, that transported dung from several farms to a central site. It went bankrupt twice, once when the original German installers ran it and again, when a consortium of farmers bought it from them. There were many complaints from local people about the trucks transporting the dung along narrow local roads. It is now run as a food waste processing plant under another company.
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Best regards,
David
mailto:dav...@kingdombio.com
Monday, January 9, 2012, 4:08:52 PM, you wrote:
| Dear Rex, I would suggest contacting Burdens who is distributing the "Portagester" system in the UK and that could be useful for your intended use and scale. Their web is www.bioplex.co.uk/portagester.shtml Best regards, Pablo. 2012/1/9 Alexander Eaton <a...@sistemabiobolsa.com> I concur on Paul's preference for smaller systems. I have seen a handful of proposals based on trucking waste from a number of small to medium farms where they have tried to show energy balance (all the trucks are methane powered, etc.), but the numbers never add up. Specifically, de-watering this waste requires relatively well developed systems at each site, and likely still leaves you with a serious amount of waste water treatment for each site to achieve healthy discharge levels (in Mexico it is the water, not the solids that is the treatment challenge). The management system is also more complex and requires a high level of coordination. The alternative de-centralized option will likely have similar initial capital costs, but you can make a better case for farmer investment as they will reap the benefits. You then have much smaller long-term operating costs, and all that energy for trucking can go to good use (or maybe still trucking some effluent fertilizer to local fields). As Paul mentioned, the option to eventually pipe gas a larger distance for centralized use is an option that may make sense (but I have not seen it outside of the European context or large landfill gas context yet). Cheers A On Sun, Jan 8, 2012 at 10:51 PM, Paul Harris <paul.har...@adelaide.edu.au> wrote: G’day Rex, Apparently a lot of the biogas comes from the fines/solutes in the liquid – I noticed that with piggery effluent the raw effluent was almost impermeable to water (it would hold puddles for quite a while) but after treatment the solids were pretty free draining (water disappeared in minutes). I will also raise my usual point in favour of distributed systems – why not put smaller (cheaper!) digesters at each farm and if necessary pipe the biogas to a central generator (depending on distance)? You will be spending a lot of energy on trucking waste in and then you have to truck the digestate out from the central facility again. The total capital cost may be higher, with more units to maintain, but you can start with one or two and spread the finances out a bit as well as helping local employment (I guess people will be working on digesters instead of driving trucks!). Happy digesting, HOOROO -- Mr. Paul Harris, Room 202, Charles Hawker Building Faculty of Sciences, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond SA 5064 Ph : +61 8 8303 7880 Fax : +61 8 8303 4386 mailto:paul.har...@adelaide.edu.au http://www.adelaide.edu.au/directory/paul.harris CRICOS Provider Number 00123M ----------------------------------------------------------- This email message is intended only for the addressee(s) and contains information which may be confidential and/or copyright. If you are not the intended recipient please do not read, save, forward, disclose, or copy the contents of this email. If this email has been sent to you in error, please notify the sender by reply email and delete this email and any copies or links to this email completely and immediately from your system. No representation is made that this email is free of viruses. Virus scanning is recommended and is the responsibility of the recipient. From: digestion-boun...@lists.bioenergylists.org [mailto:digestion-boun...@lists.bioenergylists.org] On Behalf Of REX Sent: Sunday, 8 January 2012 5:26 PM To: digestion@lists.bioenergylists.org Subject: [Digestion] 5000 dairy cow AD system Hi All, I have been approached to put together a proposal for a centralised AD using the manure from 5000 dairy cows. The intention is to pre-concentrate the dairy manure slurry and to truck the solids to a central processing unit. As silage and grass is extensively used as feed, we would be able to co-digest this with the manure to increase the gas output. Furthermore, it is intended to use the exhaust gas and the AD liquor to grow macro algae or a plant such as hyacinth (an indigenous variety that is not likely to become an invader should it get out) which can be shredded and added back to digestion. We aim to use the gas for power generation and to use the heat to keep the digester(s) warm. Questions: 1. By leaving the water behind, do we lose most/all/some of the FFA? What impact would it have on gas production? 2. Can anyone recommend a supplier of technology for this size of plant? 3. 5000 cows is an arbitrary amount at this stage - 10 farms of 500 cows each. Is there a better/more economical size? Kind regards Rex Zietsman _______________________________________________ Digestion mailing list to Send a Message to the list, use the email address digest...@bioenergylists.org to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org for more information about digestion, see Beginner's Guide to Biogas http://www.adelaide.edu.au/biogas/ and the Biogas Wiki http://biogas.wikispaces.com/ -- Alexander Eaton Sistema Biobolsa IRRI-Mexico RedBioLAC Mex cel: (55) 11522786 US cel: 970 275 4505 a...@irrimexico.org a...@sistemabiobolsa.com sistemabiobolsa.com www.irrimexico.org www.redbiolac.org _______________________________________________ Digestion mailing list to Send a Message to the list, use the email address digest...@bioenergylists.org to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org for more information about digestion, see Beginner's Guide to Biogas http://www.adelaide.edu.au/biogas/ and the Biogas Wiki http://biogas.wikispaces.com/ |
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Dr David Fulford CEnv MEI, 15, Brandon Ave, Woodley, Reading RG5 4PU
d.j.fulf...@btinternet.com, Tel: +44(0)118 326 9779 Mob: +44(0)7746 806401
Kingdom Bioenergy Ltd, www.kingdombio.com, dav...@kindombio.com
_______________________________________________ Digestion mailing list to Send a Message to the list, use the email address digest...@bioenergylists.org
to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org for more information about digestion, see Beginner's Guide to Biogas http://www.adelaide.edu.au/biogas/ and the Biogas Wiki http://biogas.wikispaces.com/
