| 1. |
- Mshandete, Anthony, et al.
(författare)
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Enhancement of anaerobic batch digestion of sisal pulp waste by mesophilic aerobic pre-treatment
- 2005
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Ingår i: Water Research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 39:8, s. 1569-1575
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Tidskriftsartikel (refereegranskat)abstract
- Pre-treatment of sisal pulp prior to its anaerobic digestion was investigated using an activated sludge mixed culture under aerobic conditions in batch bioreactors at 37 degrees C. The progression of aerobic pre-treatment of the residue in relation to the activities of some extracellular hydrolytic enzymes in the slurry was monitored. The highest activity of hydrolytic enzymes was obtained at 9 h of pre-treatment. Filter paper cellulase had a maximum activity of 0.90 IU/ml, while carboxymethyl cellulase, amylase and xylanase were produced to a maximum of about 0.40 IU/ml. The methane yield obtained after anaerobic digestion of the pre-treated pulp ranged between 0.12 and 0.24 m(3) CH4/kg VS added. The highest and lowest values were obtained for 9 and 72 h of pre-treatment, respectively. Nine hours of pre-treatment of sisal pulp prior to anaerobic digestion demonstrated a 26 % higher methane yield when compared to the sisal pulp without pre-treatment. The consortia of microorganisms in activated sludge demonstrated a useful potential in the production of hydrolases acting on major macromolecules of sisal pulp. The fact that a correlation was observed between high enzyme activity and high methane yield at 9h of aerobic pre-treatment suggests that such a short pretreatment period could be an alternative option for increasing solubilization of sisal pulp and promoting methane productivity. (c) 2005 Elsevier Ltd. All rights reserved.
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| 2. |
- Mshandete, Anthony, et al.
(författare)
-
Performance of a sisal fibre fixed-bed anaerobic digester for biogas production from sisal pulp waste
- 2005
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Ingår i: Tanzania Journal of Science. - : African Journals Online (AJOL). - 0856-1761. ; 31:2, s. 41-52
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Tidskriftsartikel (refereegranskat)abstract
- A single stage anaerobic digester employing a sisal fibre waste fixed bed was studied for biogas production from sisal pulp waste. The fibre was colonized by microorganisms involved in biogas production. The sisal pulp waste to be digested was fed from the top and was sprinkled intermittently with recirculating leachate from the material. Organic loading rates of 0.1-10 kg volatile solids (VS) m-3d-1 could be applied and methane yields in the range of 0.13-0.48 m3 CH4 kg-1 VS added were obtained. The average methane content in the biogas produced from sisal pulp waste was 55%, and the biogas production rate was 0.15-0.54 m3m-3d-1. The methane yield obtained and the highest organic loading rate that could be sustained by this simple, fixed-bed digester are indications of an attractive system in terms of performance and reliability. It is concluded that the sisal fibre waste fixed bed is a promising carrier for microbes and can be employed for long-term operation without changing the bed.
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| 3. |
- Svensson, Mattias, et al.
(författare)
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Biogas production from crop residues on a farm-scale level: is it economically feasible under conditions in Sweden?
- 2005
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Ingår i: Bioprocess and Biosystems Engineering. - : Springer Science and Business Media LLC. - 1615-7605 .- 1615-7591. ; 28:3, s. 139-148
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion would enable the energy potential of agricultural crop residues such as sugar beet tops and straw to be harnessed. Sweden is so spread out that full utilisation of this potential by centralised slurry-based technology is difficult. It appears that simple but effective high-solids reactor systems have a better chance of being economically viable on a farm-scale level (50500 kW). In the present study, the financial prospects of high-solids digestion, using either single-stage fed-batch or two-stage batch reactor systems, are compared on a farm-scale level (50 kW) with those of conventional slurry digestion, on the basis of experimental results and observations on a laboratory- and pilot-scale. The gas produced can be used for heat, combined heat and power or as vehicle fuel. The results indicate high-solids single-stage fed-batch operations to stand the best chances of being competitive, particularly in connection with organic farming. The methane yield, degree of gas utilisation, and operational costs were found to have the strongest impact on the financial success of the process.
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| 4. |
- Svensson, Mattias, et al.
(författare)
-
Biogas production from crop residues on a farm-scale level: Scale, choice of substrate and utilisation rate most important parameters for financial feasibility
- 2005
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Anaerobic digestion would enable the energy potential of agricultural crop residues such as ley crops, sugar beet tops and straw to be harnessed in Sweden. These residues are so spread out that full utilisation of the potential by centralised slurry-based technology is difficult, its appearing that simple but effective high-solids reactor systems have a better chance of being economically viable on a farm-scale level (30-300 kW). In the present study, the financial prospects of single-stage fed-batch high-solids digestion on three different scales, 51, 67 and 201 kW, were calculated, on the basis of experimental results and observations on a laboratory- and pilot-scale. The biogas was disposed as heat, combined heat and power or as vehicle fuel. The results indicate the importance of choosing substrates with a high methane yield and a high nitrogen content, and the necessity of fully utilising both the capacity of the equipment installed and the energy carriers produced.
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