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- Andersson, Sofia, et al.
(författare)
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Biofilm formation and interactions of bacterial strains found in wastewater treatment systems
- 2008
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Ingår i: FEMS Microbiology Letters. - OXFORD : BLACKWELL PUBLISHING. - 0378-1097 .- 1574-6968. ; 283:1, s. 83-90
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Tidskriftsartikel (refereegranskat)abstract
- Biofilm formation and adherence properties of 13 bacterial strains commonly found in wastewater treatment systems were studied in pure and mixed cultures using a crystal violet microtiter plate assay. Four different culture media were used, wastewater, acetate medium, glucose medium and diluted nutrient broth. The medium composition strongly affected biofilm formation. All strains were able to form pure culture biofilms within 24 h in at least one of the tested culture media and three strains were able to form biofilm in all four culture media, namely Acinetobacter calcoaceticus ATCC 23055, Comamonas denitrificans 123 and Pseudomonas aeruginosa MBL 0199. The adherence properties assessed were initial adherence, cell surface hydrophobicity, and production of amyloid fibers and extracellular polymeric substances. The growth of dual-strain biofilms showed that five organisms formed biofilm with all 13 strains while seven formed no or only weak biofilm when cocultured. In dual-strain cultures, strains with different properties were able to complement each other, giving synergistic effects. Strongest biofilm formation was observed when a mixture of all 13 bacteria were grown together. These results on attachment and biofilm formation can serve as a tool for the design of tailored systems for the degradation of municipal and industrial wastewater.
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| 2. |
- Andersson, Sofia, et al.
(författare)
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Characterization of extracellular polymeric substances from denitrifying organism Comamonas denitrificans
- 2009
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 82:3, s. 535-543
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Tidskriftsartikel (refereegranskat)abstract
- Extracellular polymeric substances (EPS) play an important role in the formation and activity of biofilms in wastewater treatment (WWT). The EPS of the denitrifying biomarker Comamonas denitrificans strain 110, produced in different culture media and growth modes, were characterized. The EPS mainly contained protein (3-37%), nucleic acids (9-50%), and carbohydrates (3-21%). The extracellular DNA was found to be important for initial biofilm formation since biofilm, but not planktonic growth, was inhibited in the presence of DNase. The polysaccharide fraction appeared to consist of at least two distinct polymers, one branched fraction (A) made up of glucose and mannose with a molecular weight around 100 kDa. The other fraction (B) was larger and consisted of ribose, mannose, glucose, rhamnose, arabinose, galactose, and N-acetylglucosamine. Fraction B polysaccharides were mainly found in capsular EPS which was the dominant type in biofilms and agar-grown colonies. Fraction A was abundant in the released EPS, the dominant type in planktonic cultures. Biofilm and agar-grown EPS displayed similar overall properties while planktonic EPS showed clear compositional disparity. This study presents results on the physiology of a key WWT organism, which may be useful in the future development of improved biofilm techniques for WWT purposes.
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| 4. |
- Dalhammar, Carl
(författare)
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An Emerging Product Approach in Environmental Law: Incorporating the life cycle perspective
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the noticeable trends in recent years is that products have received increasing attention in environmental policy. The focus on products and their life cycle impacts is often referred to as ?life cycle thinking?. This implies a shift away from the traditional focus on production processes and the environmental impacts of point-source pollution, towards a stronger focus on emissions from the other stages of the life cycle of products. Consumer products have a number of life cycle phases, including: the extraction of raw materials and refinement, production of intermediates and finished goods, sales, transportation, storage, use/consumption and final disposal. The environmental impacts from various life cycle phases can be reduced through improved product design and various measures taken by actors throughout the product chain. Minimising life cycle environmental impacts requires initiative and participation from several key actors throughout the product chain, and this in turn requires clear incentives. A key question concerns how much government intervention is necessary for this purpose, or what type of government policies that are necessary or desirable. The aim of this research has been to explore the potential to use law as a tool to improve the environmental performance of products over the entire life cycle. In doing so, it examines the potential to use mandatory legal standards for life cycle environmental improvements, taking into account the political and economic context where laws are initiated, negotiated and implemented.
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| 8. |
- Dalhammar, Carl
(författare)
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Miljökvalitetsmålen i rättstillämpningen - vad tycker användarna
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En kärnfråga i miljömålsarbetet rör hur miljömålen kan respektive bör användas vid tillämpningen av miljöbalkens olika styrmedel. Rapporten redogör för olika aktörers erfarenheter och åsikter i dessa frågor. Forskningen bygger på djupintervjuer med personer inom bland annat kommuner, länsstyrelser, miljödomstolar och näringslivet. Fokus ligger på två styrmedel: tillstånd till miljöfarlig verksamhet och miljötillsyn. I rapporten redogörs för de problem som olika myndigheter ställs inför när de ska integrera miljömålsfrågor i det lagstyrda myndighetsarbetet, hur de ser på den fortsatta utvecklingen, och deras behov av stöd och resurser. Vidare undersöks hur industrin ser på miljömålen och hur dessa kan respektive bör användas vid tillståndsgivning och tillsyn.
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