| 1. |
- Hey, Tobias, et al.
(författare)
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Evaluation of direct membrane filtration and direct forward osmosis as concepts for compact and energy-positive municipal wastewater treatment
- 2018
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Ingår i: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 39:3, s. 264-276
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Tidskriftsartikel (refereegranskat)abstract
- Municipal wastewater treatment commonly involves mechanical, biological and chemical treatment steps to protect humans and the environment from adverse effects. Membrane technology has gained increasing attention as an alternative to conventional wastewater treatment due to increased urbanization. Among the available membrane technologies, microfiltration (MF) and forward osmosis (FO) have been selected for this study due to their specific characteristics, such as compactness and efficient removal of particles. In this study, two treatment concepts were evaluated with regard to their specific electricity, energy and area demands. Both concepts would fulfil the Swedish discharge demands for small- and medium-sized wastewater treatment plants at full scale: (1) direct MF and (2) direct FO with seawater as the draw solution. The framework of this study is based on a combination of data obtained from bench- and pilot-scale experiments applying direct MF and FO, respectively. Additionally, available complementary data from a Swedish full-scale wastewater treatment plant and the literature were used to evaluate the concepts in depth. The results of this study indicate that both concepts are net positive with respect to electricity and energy, as more biogas can be produced compared to that using conventional wastewater treatment. Furthermore, the specific area demand is significantly reduced. This study demonstrates that municipal wastewater could be treated in a more energy- and area-efficient manner with techniques that are already commercially available and with future membrane technology.
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| 2. |
- Hey, Tobias, et al.
(författare)
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Influences of mechanical pretreatment on the non-biological treatment of municipal wastewater by forward osmosis
- 2017
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Ingår i: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 38:18, s. 2295-2304
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Tidskriftsartikel (refereegranskat)abstract
- Municipal wastewater treatment involves mechanical, biological and chemical treatment steps for protecting the environment from adverse effects. The biological treatment step consumes the most energy and can create greenhouse gases. This study investigates municipal wastewater treatment without the biological treatment step, including the effects of different pretreatment configurations, for example, direct membrane filtration before forward osmosis. Forward osmosis was tested using raw wastewater and wastewater subjected to different types of mechanical pretreatment, for example, microsieving and microfiltration permeation, as a potential technology for municipal wastewater treatment. Forward osmosis was performed using Aquaporin Inside™ and Hydration Technologies Inc. (HTI) membranes with NaCl as the draw solution. Both types of forward osmosis membranes were tested in parallel for the different types of pretreated feed and evaluated in terms of water flux and solute rejection, that is, biochemical oxygen demand (BOD7) and total and soluble phosphorus contents. The Aquaporin and HTI membranes achieved a stable water flux with rejection rates of more than 96% for BOD7 and total and soluble phosphorus, regardless of the type of mechanical pretreated wastewater considered. This result indicates that forward osmosis membranes can tolerate exposure to municipal waste water and that the permeate can fulfil the Swedish discharge limits.
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| 3. |
- Nilsson, Filip, et al.
(författare)
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Impact of activated sludge ozonation on filamentous bacteria viability and possible added benefits
- 2019
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Ingår i: Environmental Technology. - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 40:20, s. 2601-2607
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Tidskriftsartikel (refereegranskat)abstract
- Ozone was applied to return activated sludge in full-scale to study how ozone impacts filamentous bacteria viability (Live/Dead®). Additionally, the ozonated sludges were subjected to anaerobic digestion trials and analysis of micropollutants. Ozone treatment (3-4.8 g O3/kg TSS) improved the settling properties of the sludge by lowering the diluted sludge volume with 7-35%. Ozone inactivated filamentous bacteria outside the floc structures and the fraction of inactivated filaments increased with an increasing ozone dose. It was observed that ozone treatment may act selectively towards different types of filaments. With respect to the two dominating morphotypes present, Type 0041 filamentous bacteria were found to be more resistant to ozone attack than Microthrix parvicella. Thus, higher ozone doses may be required to mitigate sludge bulking caused by Type 0041 filaments. No effects could be discerned by ozone addition on neither the methane production of the sludge nor on the concentrations of micropollutants analysed for this study. The lack of effect on both methane production and micropollutant removal was deemed to be caused by insufficient ozone doses.
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| 4. |
- Nilsson, Filip, et al.
(författare)
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Removal of pharmaceuticals with ozone at 10 Swedish wastewater treatment plants
- 2017
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Ingår i: Water Practice & Technology. - : IWA Publishing. - 1751-231X. ; 12:4, s. 871-881
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Tidskriftsartikel (refereegranskat)abstract
- Pilot-scale tests were run with ozonation for reduction of 24 pharmaceuticals at 10 full-scale wastewater treatment plants in southern Sweden. Reduction was evaluated based on doses of 3, 5 and 7 g O3/m3 at all plants. The reduction of pharmaceuticals reached on average 65% at 3 g O3/m3, 78% at 5 g O3/m3 and 88% for 7 g O3/m3 in terms of total concentration of pharmaceuticals. Specific ozone dose (ratio O3:TOC) was found to be highly influential on pharmaceutical removal. At two WWTPs, the pharmaceutical removal was severely reduced.
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| 5. |
- Piculell, Maria, et al.
(författare)
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The inhibitory effects of reject water on nitrifying populations grown at different biofilm thickness
- 2016
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 104:1 Nov, s. 292-302
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Tidskriftsartikel (refereegranskat)abstract
- Suppression of nitrite oxidizing bacteria (NOB) is of vital importance to achieve successful, energy efficient, mainstream anammox processes for wastewater treatment. In this study, biofilm carriers from a fully nitrifying MBBR system, fed with mainstream wastewater, were temporarily exposed to reject water from sludge dewatering, to evaluate this as a possible strategy to inhibit NOB and achieve nitrite production under realistic conditions. Two different carrier types were compared, in which biofilm thickness was maintained at approximately 400 and 50 mm, respectively, and reject treatment was tested at different exposure time and loading rates. Reject exposure almost always resulted in an increased nitrite production in the thinner biofilm, and overall, nitrifiers growing in the thin biofilm were more sensitive than those grown in the thicker biofilm. The effect from reject exposure remained in the systems for four days after returning to mainstream operation, with nitrite production gradually increasing for three days. Increased concentrations of free ammonia correlated with reject exposure and may be the cause of inhibition, although other factors cannot be excluded.
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