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Södertälje, Sweden

Wahlberg C.,Stockholm Water Company | Bjorlenius B.,Stockholm Water Company | Paxeus N.,Gryaab AB
Water Science and Technology | Year: 2011

Mass flows of 13 pharmaceutical active ingredients (APIs) found in drinking water were studied in the water cycle of Stockholm. Data were collected by analyzing samples of surface water, raw water and drinking water as well as influents, effluents and sludges from waste water treatment plants (WWTPs) in Stockholm area. A mass balance was performed, based on sold amounts of pharmaceuticals and the measured concentrations in water and sludge. The selected APIs were all present in WWTP effluents and the removal rates for many of them were poor. Mass balance calculations showed that the three studied WWTPs in Stockholm release considerable amounts of the selected APIs into the Baltic Sea while the portions ending up in WWTP sludge were significantly lower. The levels of APIs found in drinking water are low at present, but may increase in the future unless the releases from WWTPs in the catchment of Lake Mälaren are mitigated. © IWA Publishing 2011. Source


Gustavsson D.J.I.,VA SYD | Tumlin S.,Gryaab AB
Water Science and Technology | Year: 2013

This study estimates the carbon footprints of 16 municipal wastewater treatment plants (WWTPs), all situated in Scandinavian countries, by using a simple model. The carbon footprint calculations were based on operational data, literature emission factors (efs) and measurements of greenhouse gas emissions at some of the studied WWTPs. No carbon neutral WWTPs were found. The carbon footprints ranged between 7 and 108 kg CO2e P.E.-1 year-1. Generally, the major positive contributors to the carbon footprint were direct emissions of nitrous oxide from wastewater treatment. Whether heat pumps for effluents have high coefficient of performance or not is extremely important for the carbon footprint. The choice of efs largely influenced the carbon footprint. Increased biogas production, efficient biogas usage, and decreased addition of external fossil carbon source for denitrification are important activities to decrease the carbon footprint of a WWTP. © IWA Publishing 2013. Source


Wilen B.-M.,Chalmers University of Technology | Johansen A.,Chalmers University of Technology | Mattsson A.,Gryaab AB
Water Practice and Technology | Year: 2012

To meet stricter effluent discharge limits of total phosphorus, microscreens can be applied for tertiary effluent treatment. The Rya WWTP has recently been upgraded with microscreens in the form of disc filters. Extensive characterisation of the wastewater from different locations in the plant (influent, after primary settling) and secondary settler effluent, was performed to increase the understanding of the potential of removing different components from the wastewater. The wastewater was fractionated by filtration through filter cloths with pore sizes 40, 20, 15, and 10 μm and through finer filters with pore size 1.2, 0.45, 0.2 and 0.1 μm. Particle size analysis (PSA) was used to assess the removal efficiency of the filter cloths. High removal degrees were achieved were particles larger or equal in size to the pore size were strained. Some floc break-up took place leading to an increased number of small particles (1-5 μm) after filtration. The suspended solids concentration could be reduced to 1 mg/l with total phosphorus concentrations of <0.2 mg/l. Some removal of metals could be observed when filtering wastewater with higher concentrations (influent and secondary settler effluent) whereas no effect could be seen for the effluent wastewater, probably due to the low concentrations present. The results from this study indicate a poor removal efficiency of pathogens measured as indicator microorganisms. © IWA Publishing 2012. Source


Wilen B.-M.,Chalmers University of Technology | Lumley D.,Gryaab AB | Mattsson A.,Gryaab AB | Mino T.,University of Tokyo
Water Environment Research | Year: 2010

A comprehensive study of the dynamics in settling and flocculation properties at a full-scale activated sludge treatment plant with secondary settlers operated at their maximum capacity is presented. An extensive set of process data was analyzed to assess physical parameters affecting the capacity and performance of the secondary settlers. There was a large variation in the settling and compaction properties, and they changed quickly, as a result of the short sludge age. Even though the flocculation properties changed throughout the year, they were generally improved during the summer, with lower values of effluent turbidity and effluent suspended solids concentration. The shear sensitivity, which is a measure of floc stability, was higher during the winter, when the water temperatures were lower. The sludge floc morphology had, in general, a different internal structure, with more round microbial colonies during the warmer summer months and a more net-like open structure during the winter. Source


Holmberg A.,Gothenburg University | Fogel J.,Gothenburg University | Albertsson E.,Gothenburg University | Fick J.,Umea University | And 5 more authors.
Journal of Hazardous Materials | Year: 2011

Citalopram is one of several selective serotonin reuptake inhibitors (SSRIs) commonly found in treated sewage effluents. Accordingly, there are concerns about possible adverse effects of SSRIs on aquatic organisms, particularly behavioural effects similar to those associated with SSRI use in humans. Rainbow trout fry and adult male guppies were therefore exposed to waterborne citalopram, ranging from environmentally relevant to high concentrations (1, 10, 100 μg/L) for 3-7 days. Under these experimental conditions citalopram does not appear to cause significant effects on aggression in rainbow trout fry or on sexual behaviour in male guppies. This may be explained by a relatively low uptake of citalopram from water to fish. © 2011 Elsevier B.V. Source

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