| 1. |
- Anderson, Leif G, 1951, et al.
(författare)
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Shelf-Basin interaction along the East Siberian Sea
- 2017
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Ingår i: Ocean Science. - : Copernicus GmbH. - 1812-0784 .- 1812-0792. ; 13:2, s. 349-363
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Tidskriftsartikel (refereegranskat)abstract
- Extensive biogeochemical transformation of organic matter takes place in the shallow continental shelf seas of Siberia. This, in combination with brine production from sea-ice formation, results in cold bottom waters with relatively high salinity and nutrient concentrations, as well as low oxygen and pH levels. Data from the SWERUS-C3 expedition with icebreaker Oden, from July to September 2014, show the distribution of such nutrient-rich, cold bottom waters along the continental margin from about 140 to 180 degrees E. The water with maximum nutrient concentration, classically named the upper halocline, is absent over the Lomonosov Ridge at 140 degrees E, while it appears in the Makarov Basin at 150 degrees E and intensifies further eastwards. At the intercept between the Mendeleev Ridge and the East Siberian continental shelf slope, the nutrient maximum is still intense, but distributed across a larger depth interval. The nutrient-rich water is found here at salinities of up to similar to 34.5, i.e. in the water classically named lower halocline. East of 170 degrees E transient tracers show significantly less ventilated waters below about 150 m water depth. This likely results from a local isolation of waters over the Chukchi Abyssal Plain as the boundary current from the west is steered away from this area by the bathymetry of the Mendeleev Ridge. The water with salinities of similar to 34.5 has high nutrients and low oxygen concentrations as well as low pH, typically indicating decay of organic matter. A deficit in nitrate relative to phosphate suggests that this process partly occurs under hypoxia. We conclude that the high nutrient water with salinity similar to 34.5 are formed on the shelf slope in the Mendeleev Ridge region from interior basin water that is trapped for enough time to attain its signature through interaction with the sediment.
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| 2. |
- Sandberg, Maria, 1968-, et al.
(författare)
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Black Liquor and Alkaline Shocks in a Multiple Stage Biological Treatment Plant
- 2008
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Ingår i: Journal of Environmental Engineering and Science. - 1496-2551 .- 1496-256X. ; 7:4, s. 335-344
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Tidskriftsartikel (refereegranskat)abstract
- To find the impact that alkaline and black liquor spills have on multiple stage biological treatment plants, trials were made in a MultiBio lab-scale treatment plant. It was shown that the concentration of black liquor was diluted between the multiple stages. The initial bacterial stages were inhibited by high concentration of black liquor but recovered when the concentration decreased. Low pH in the feed contaminated with black liquor gave less inhibition than high pH. In a MultiBio treatment plant the active sludge stages, which are sensitive to toxic spills, are placed after the fast growing bacterial stages and are therefore protected. During normal conditions the activated sludge stages receive low concentrations of biodegradable COD. During the trials extra COD in the form of diluted black liquor induced the COD reduction. To evaluate the results, measured concentrations were compared with a computer model.
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| 3. |
- Stoica, Alina, 1980-, et al.
(författare)
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Energy Use and Recovery Strategies within Wastewater Treatment and Sludge Handling at Pulp and Paper Mills
- 2009
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 100:14, s. 3497-3505
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an inclusive approach with focus on energy use and recovery in wastewater management, including wastewater treatment (WWT) and sludge handling. Process data from three Swedish mills and a mathematical model were used to evaluate seven sludge handling strategies. The results indicate that excess energy use in WWT processes counters the potential energy recovery in the sludge handling systems. Energy use in WWT processes is recommended to aim for sufficient effluent treatment, not for sludge reduction. Increased secondary sludge production is favourable from an energy point of view provided it is used as a substrate for heat, biogas or electricity production.
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