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- Granström, Karin, 1974-, et al.
(författare)
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Biogas from algae farmed in pulp and paper mill wastewater
- 2015
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Ingår i: GGROS 2015, Örnsköldsvik, Sweden, 23-25 March 2015..
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Konferensbidrag (refereegranskat)abstract
- Pulp and paper mills have waste streams that can be used for the farming of algae. The mills wastewater treatment provides heat to the algae ponds and the flue gas provides carbon dioxide. A current project is aiming at producing oil, for biodiesel or lubricating oil, from mill-farmed algae. Ten pools have been constructed and seeded with different strains of algae. After harvest and separation of oil, there is a leftover algae pulp. The fate of this algae remnant is an important part in achieving economic and energy viability for the whole process.The purpose of this work was to study the potential to produce biogas from algae grown in pulp and paper mill wastewaters, for different algae strains and pond conditions, with differing degrees of oil separation before the anaerobic digestion stage. The methane potential of the various algae pulps was tested by anaerobic digestion batch assays under thermophilic conditions for 23 days. Pre-treatment of substrate is sometimes done in order to reduce the necessary retention time of biogas production. One batch of algae was subjected to either thermal pre-treatment or NaOH or comminution, to assess the effect on these methods on methane production.Ammonia concentration and pH in the digestate was analyzed to monitor the anaerobic digestion process, and the algae pulp’s content of fat, protein and carbohydrates were analyzed to characterize the substrate. In addition, the dewaterability of algae and of algae digestate was examined, as the dewaterability affects transport costs and possible use of the digestate.During the first year of operation, the algae in the range pond produced 186 ml CH4/g VS. The pre-treatments did not significantly affect the methane potential. The second year of operation saw more adapted strains of algae which are expected to produce somewhat different results [data from these experiments can be presented at the conference]. The research is of importance for the development of the biogas market as new substrates are needed to reach the volumes that are necessary to achieve economic viability for biogas plants. By characterizing the algae, it should be easier to see which role they are suitable to play in a co-digestion mix. Furthermore, the production of bio-oil and biogas together benefit the bioenergy system as a whole.
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| 3. |
- Granström, Karin, 1974-
(författare)
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Regler för hantering av rötrest
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- InnehållsförteckningINLEDNINGPROBLEM MED ATT TA TILLVARA RÖTRESTTungmetallerSmittaREGLERING AV ANVÄNDANDET AV RÖTREST SOM GÖDNINGCertifiering av biogödselHygieniseringskrav för biogödselCertifiering av rötslamHygieniseringskrav för rötslamACCEPTANS?MÖJLIGHETER OCH RISKER MED SAMRÖTNINGREFERENSER
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| 5. |
- Granström, Karin, 1974-, et al.
(författare)
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Pre-Treatment To Enhance Biogas Yield from Pulp and Paper Mill Sludge
- 2014
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Ingår i: Journal of Chemistry and Chemical Engineering. - Libertyvill IL : David Publishing Company. - 1934-7375 .- 1934-7383. ; :8, s. 825-833
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to study the potential to enhance biogas production from pulp and paper mill sludge by the use of thermal pre-treatment in combination with chemical pre-treatment. Biogas from waste is a renewable fuel with very low emissions during combustion. To further reduce the use of fossil fuels, more biogas substrates are necessary. Pulp and paper mill sludge is a large untapped reservoir of potential biogas. Pulp and paper mill sludge was collected from a mill that produces both pulp and paper and has a modified waste activated sludge system as part of its wastewater treatment. Pre-treatments were chosen heat (70 oC or 140 oC) combined with either acid (pH 2 or pH 4) or base (pH 9 or pH 11, obtained with Ca(OH)2 or NaOH). Biogas potential was tested by anaerobic digestion batch assays under mesophilic conditions. All pre-treatments were tested in six replicates. Biogas volume was measured with a gas-tight syringe and methane concentration was measured with a gas chromatograph. The methane yield from sludge subjected to thermal pre-treatment at 70 oC did not differ from the untreated sludge, but thermal pre-treatment at 140 oC had a positive effect. Within the 70 oC thermal pre-treatment group, the pH 2 acid was the most successful chemical pre-treatment, and Ca(OH)2 pH 9 had the least effect with no measurable improvement in methane yield. For the 140 oC thermal pre-treatment group, acid and NaOH impacted methane production negatively, while the Ca(OH)2-treated sludge did not differ from sludge with no chemical pre-treatment. In conclusion, thermal pre-treatment at 70 oC showed no effect, whereas, pre-treatment at 140 oC improved methane yield with 170%, and for this sludge additional, chemical pre-treatments are unnecessary.
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