| 1. |
- Moshi, Anselm, et al.
(författare)
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Production of raw starch-degrading enzyme by Aspergillus sp. and its use in conversion of inedible wild cassava flour to bioethanol.
- 2015
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Ingår i: Journal of Bioscience and Bioengineering. - : Elsevier BV. - 1347-4421 .- 1389-1723.
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Tidskriftsartikel (refereegranskat)abstract
- The major bottlenecks in achieving competitive bioethanol fuel are the high cost of feedstock, energy and enzymes employed in pretreatment prior to fermentation. Lignocellulosic biomass has been proposed as an alternative feedstock, but because of its complexity, economic viability is yet to be realized. Therefore, research around non-conventional feedstocks and deployment of bioconversion approaches that downsize the cost of energy and enzymes is justified. In this study, a non-conventional feedstock, inedible wild cassava was used for bioethanol production. Bioconversion of raw starch from the wild cassava to bioethanol at low temperature was investigated using both a co-culture of Aspergillus sp. and Saccharomyces cerevisiae, and a monoculture of the later with enzyme preparation from the former. A newly isolated strain of Aspergillus sp. MZA-3 produced raw starch-degrading enzyme which displayed highest activity of 3.3 U/mL towards raw starch from wild cassava at 50°C, pH 5.5. A co-culture of MZA-3 and S. cerevisiae; and a monoculture of S. cerevisiae and MZA-3 enzyme (both supplemented with glucoamylase) resulted into bioethanol yield (percentage of the theoretical yield) of 91 and 95 at efficiency (percentage) of 84 and 96, respectively. Direct bioconversion of raw starch to bioethanol was achieved at 30°C through the co-culture approach. This could be attractive since it may significantly downsize energy expenses.
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| 2. |
- Paul, Catherine, et al.
(författare)
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A GH57 4-α-glucanotransferase of hyperthermophilic origin with potential for alkyl glycoside production.
- 2015
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 99:17, s. 7101-7113
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Tidskriftsartikel (refereegranskat)abstract
- 4-α-Glucanotransferase (GTase) enzymes (EC 2.4.1.25) modulate the size of α-glucans by cleaving and reforming α-1,4 glycosidic bonds in α-glucans, an essential process in starch and glycogen metabolism in plants and microorganisms. The glycoside hydrolase family 57 enzyme (GTase57) studied in the current work catalyzes both disproportionation and cyclization reactions. Amylose was converted into cyclic amylose (with a minimum size of 17 glucose monomers) as well as to a spectrum of maltodextrins, but in contrast to glycoside hydrolase family 13 cyclodextrin glucanotransferases (CGTases), no production of cyclodextrins (C6-C8) was observed. GTase57 also effectively produced alkyl-glycosides with long α-glucan chains from dodecyl-β-D-maltoside and starch, demonstrating the potential of the enzyme to produce novel variants of surfactants. Importantly, the GTase57 has excellent thermostability with a maximal activity at 95 °C and an activity half-life of 150 min at 90 °C which is highly advantageous in this manufacturing process suggesting that enzymes from this relatively uncharacterized family, GH57, can be powerful biocatalysts for the production of large head group glucosides from soluble starch.
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| 3. |
- Suresh, Prashanth, et al.
(författare)
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Arsenic adsorption by iron-aluminium hydroxide coated onto macroporous supports : Insights from X-ray absorption spectroscopy and comparison with granular ferric hydroxides
- 2016
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 302, s. 166-174
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Tidskriftsartikel (refereegranskat)abstract
- This paper evaluates the arsenic adsorption characteristics of a macroporous polymer coated with coprecipitated iron-aluminium hydroxides (MHCMP). The MHCMP adsorbent-composite fits best with a pseudo-second order model for As(III) and a pseudo-first order kinetic model for As(V). The MHCMP shows a maximum adsorption capacity of 82.3 and 49.6 mgAs/g adsorbent for As(III) and As(V) ions respectively, and adsorption followed the Langmuir model. Extended X-ray absorption fine structure showed that binding of As(III) ions were confirmed to take place on the iron hydroxides coated on the MHCMP, whereas for As(V) ions the binding specificity could not be attributed to one particular metal hydroxide. As(III) formed a bidentate mononuclear complex with Fe sites, whereas As(V) indicated on a bidentate binuclear complex with Al sites or monodentate with Fe sites on the adsorbent. The column experiments were run in a well water spiked with a low concentration of As(III) (100 mu g/L) and a commercially available adsorbent (GEH (R) 102) based on granular iron-hydroxide was used for comparison. It was found that the MHCMP was able to treat 7 times more volume of well water as compared to GEH (R) 102, maintaining the threshold concentration of less than 10 mu gAs/L, indicating that the MHCMP is a superior adsorbent.
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| 4. |
- Önnby, Linda, et al.
(författare)
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Applications of Cryogels in Water and Wastewater Treatment
- 2016
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Ingår i: Supermacroporous Cryogels : Biomedical and Biotechnological Applications - Biomedical and Biotechnological Applications. - : CRC Press. - 9781482228823 ; , s. 331-364
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Bokkapitel (refereegranskat)abstract
- Cryogels have potential for applications in water and wastewater treatment. However, maximum levels of exposure to both incorporated materials in cryogels (i.e., nanoparticles [NPs]) and monomers, as a result of leakage, must be established before cryogel composites can be implemented in the large-scale treatment of water. Other factors, such as cost and reuse, must also be studied for each specific adsorbent. One of the greater advantages of cryogels is the flexibility of their preparation. The material can be prepared as monoliths, discs, beads or particles, to suit specific requirements. Results on a laboratory scale may be different from those obtained when treating real water and wastewater due to differences in scale and water chemistry. The social acceptance of the technology and its overall environmental impact must also be assessed. This chapter starts with describing how cryogel materials have been developed from their initial applications in water treatment to more recent developments. This is followed by current published results obtained from the treatment of water from different sources, including both lab-scale evaluations as well as real water samples. As the main application of cryogels within water treatment today is as adsorbent materials, these will be given the main focus for this chapter but still include more recent research results from applications regarding disinfection and oil absorption. The main pollutants of interest for this chapter are inorganic pollutants such as metals and metalloids (e.g. cadmium and arsenic), but organic contaminants are also mentioned. Future challenges in this area today, regarding cryogel applications, cover the need for system regeneration, the deposition of the pollutant and, finally, the total cost of the treatment.
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| 5. |
- Önnby, Linda, et al.
(författare)
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Cryogel-supported titanate nanotubes for waste treatment: Impact on methane production and bio-fertilizer quality.
- 2015
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 207, s. 58-66
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Tidskriftsartikel (refereegranskat)abstract
- By reducing the cadmium (Cd(2+)) content in biomass used for bio-based products such as biogas, a less toxic bio-based fertilizer can be obtained. In this work, we demonstrate how a macroporous polymer can support titanate nanotubes, and we take advantage of its known selective adsorption behavior towards Cd(2+) in an adsorption process from real nutrient-rich process water from hydrolysis of seaweed, a pollutant-rich biomass. We show that pretreatment steps involving alteration in area-to-volume ratio performed in aerated and acidic conditions release the most Cd(2+) from the solid material. By integrating an adsorption step between hydrolysis and the biomethane, we show that it was possible to obtain high Cd(2+) removal (ca. 94%) despite molar excess (between 100 and 500) of co-present ions (e.g., Mg(2+), Ca(2+), Na(+), K(+)) and with maintained total phosphorous content. The bio-methane potential did not significantly decrease as compared to a process without cadmium removal and the yielded bio-fertilizer followed Swedish guideline values. This study provides a sound and promising alternative for a novel remediation step, enabling higher use of otherwise tricky and to some extent overlooked biomass sources.
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