miun.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
HALMBASERAD DJUPSTRÖGÖDSEL I KONTINUERLIGA BIOGASPROCESSER PÅ GÅRDSNIVÅ
Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
2012 (Swedish)Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Production of biogas from organic waste is one part in a sustainable energy system.  Biogas based on residues and organic materials from agricultural production can increase the level of energy self-sufficiency on the farm and will provide a better recycling of nutrients. For that reason it is important to development methods to increase the efficiency at agricultural based biogas. Biogas production on farm scale level is often dimensioned on the quantity of the liquid manure available, which has high water content. This results in a relatively low utilization of the microorganisms in the biogas process. On the other hand, most livestock farms have access to manure which is mixed with bedding material (often straw), called “deep litter manure”. Solid materials to be processed in the anaerobic process need some kind of pre-treatment and the milling, pumping and mixing of the substrates that are needed, results in an increase of energy requirements. The study was conducted to identify the possibilities for a more efficient utilization of the anaerobic digester and a better energy yield when deep litter manure is added to the process. Managing deep litter manure in the biogas process also results in an increase in the availability of nitrogen in the farm's manure.

To investigate the relevance of pre-treatment for the biogas potential (B0) of deep litter manure a chopping method for particle size reduction was developed in the project. Deep litter manure from two farms was used. The potential for biogas was investigated in a batchprocess, in a process temperature of 39 C °. Methane and carbon dioxide were analyzed in gas chromatography to calculate the methane production from deep litter manure. The results showed that the production of methane from the chopped sample of deep litter manure was twice as high compared to the production from the untreated sample. Furthermore, the specific methane yield of the first 13 days was significantly higher for the pretreated fraction of the substrate, 156 l VS CH4/kg, compared with 62 l CH4/kg VS of the untreated sample. A fast startup phase for the biogas process will decrease the retention time form the substrate in the digester. No significant difference could be demonstrated in the experiments with regards to different degrees of chopping of the substrate.

One problem of mechanical pre-treatment methods of the solid substrate is the energy consumption.  The method is however the most common on farm scale biogas digesters, according to the interview conducted among Swedish suppliers of biogas systems. The Swedish suppliers recommend a solution in which the solid substrate is mixed with the liquid substrate in a pre-treatment reactor.  The experiments show that solid substrate provides more gas at the same time as it costs energy and investment to get it into the biogas plant. Results of the batch experiment were used to calculate the possible investment level for pre-treatment methods. An investment level of about 450 000 SEK with an amortization period of ten years and operating costs of 10% of the amount, is needed in order include deep litter manure in the biogas process. The possibility for a farm to use all its manure in the biogas process will provide better biogas yields, in addition to greater effect in relation to the invested volume of the digester. The potential of deep litter manure in farm biogas process should be carefully analyzed on a case-by-case basis as the heterogeneity of the substrate is large and the energy exchange is strongly connected with the choice of pre-treatment technology.

Place, publisher, year, edition, pages
2012. , p. 43
Keywords [en]
Farm scale biogas production, deep litter manure, mechanical pre-treatment, batch process
National Category
Environmental Sciences
Identifiers
URN: urn:nbn:se:miun:diva-17343OAI: oai:DiVA.org:miun-17343DiVA, id: diva2:567850
Subject / course
Ecotechnology and Environmental Science
Presentation
2010-11-18, L210, Mittuniversitetet, Östersund, 13:50 (English)
Supervisors
Examiners
Available from: 2013-11-06 Created: 2012-11-14 Last updated: 2013-11-06Bibliographically approved

Open Access in DiVA

No full text in DiVA

By organisation
Department of Engineering and Sustainable Development
Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 100 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf