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- Svensson, Mattias, et al.
(författare)
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Startup of an anaerobic single stage digester with a fixed wheat straw bed
- 2001
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Ingår i: 9th World Congress, Anaerobic Digestion 2001, Anaerobic Conversion for Sustainability, Proceedings. - 9076019169 ; , s. 549-551
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The most common form of technology for energy utilization via anaerobic treatment is slurry digestion with a low solids contents, such as sewage sludge or manure. Process control and maintenance are relatively simple, but costs involved with liquid handling and heating favour large, centralised plants. Raising the solids content of a digester to 30% significantly improves the economy of anaerobic digestion, increasing the methane production per volume unit reactor, and avoiding the handling and heating of large volumes of process water. One simple and potentially cheap method of high-solids reactor implementation is a single stage fixed bed reactor, with a solid substrate as the bed and a recycled leachate stream One potential problem with this design is an initial organic acid production during reactor startup, which originates from the easily degradable substrate. A low initial loading rate gives a safer but prolonged startup, and decreases gas production in this period. The choice of substrate strongly influences the probability of clogging. A more careful choice of carrier material allows quicker startup, and reduces the risk of clogging. The material should degrade slowly, to avoid overload during startup, and have a rigid structure in order to avoid clogging. This bed can then be fed from the top with more easily degradable substrate, e.g. crop residue. In this study, we demonstrate startup of a single stage wheat straw (low biodegradability) reactor in a fixed bed.
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| 2. |
- Svensson, Mattias, et al.
(författare)
-
The effect of packing density on the startup and operation of an anaerobic single stage fixed wheat straw bed digester
- 2002
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Ingår i: Proceedings of 3rd International Symposium for Anaerobic Digestion of Solid Wastes. ; , s. 14-14
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In Southern Sweden, production of renewable energy from crop residues digestion is viewed as a worthwhile alternative. Also, the process gives valuable mineralised nitrogen as a by-product, which when produced at farm-scale can be recycled for ecological farming. It is difficult to achieve economic utilisation of crop residues in centralised slurry digestion, mainly because of the greater transport costs. Traditional reactor designs have a too low cost efficiency on farm-scale level, and therefore it is essential to introduce technologies and practices leading to economically viable reactor systems on this scale. One very simple reactor design being considered is the vertical column fixed bed digester. This allows relatively high loading rates, combined with a low maintenance requirement. Plant material can be used as a biofilm carrier, and is an inexpensive and highly efficient alternative to traditional support materials, and wheat straw, with its rigid structure and low biodegradability, is a good candidate. In this study, the influence of packing density on startup and single stage semi-batch operation of vertical column fixed bed digesters was examined in one laboratory-scale and three pilot-scale systems.
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