| 1. |
- Mattsson, Ann, 1964, et al.
(författare)
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Heavy metal content of Swedish municipal wastewater sludge - status and goals
- 2017
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 76:4, s. 869-876
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Tidskriftsartikel (refereegranskat)abstract
- In 2014, 25% of the sludge produced at Swedish municipal wastewater treatment plants was applied to agricultural land. Even though the Swedish heavy metal limits for sludge to be used in agriculture are amongst the most stringent in the EU, more stringent heavy metal limits are proposed. Most sludge applied to agricultural land is recycled within a certification system, Revaq. Revaq has targets for control at source management and improvement of sludge quality. Statistics based on data collected within the Revaq system was used to differentiate between local and general sources of heavy metals and assess the need to improve sludge quality. The analysis indicates that proposed future national limits on the quality of the sludge can be met by most of the sludge. The improvement needed for about 20% of the sludge is feasible through local control at source management. The levels of cadmium, copper and mercury need to be reduced if these metals are not to limit the amount of sludge that may be applied per unit area of arable land. Finally, the long term Revaq targets for cadmium and silver will be difficult to meet.
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| 2. |
- Modin, Oskar, 1980, et al.
(författare)
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A relationship between phages and organic carbon in wastewater treatment plant effluents
- 2022
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Ingår i: Water Research X. - : Elsevier BV. - 2589-9147. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- With stringent effluent requirements and the implementation of new processes for micropollutant removal, it is increasingly important for wastewater treatment plants (WWTPs) to understand the factors affecting effluent quality. Phages (viruses infecting prokaryotes) are abundant in the biological treatment processes. They can contribute to organic carbon in the treated effluent both because they are organic in nature and occur in the effluent and because they cause lysis of microorganisms. Today very little is known about the effects of phages on effluent quality. The goal of this study was, therefore, to determine the relationship between phages and organic carbon in WWTP effluents. We also examined the diversity, taxonomy, and host-association of DNA phages using metagenomics. Effluent samples were collected from four WWTPs treating municipal wastewater. Significant differences in both organic carbon and virus-like particle concentrations were observed between the plants and there was a linear relationship between the two parameters. The phage communities were diverse with many members being taxonomically unclassified. Putative hosts were dominated by bacteria known to be abundant in activated sludge systems such as Comamonadaceae. The composition of phages differed between the WWTPs, suggesting that local conditions shape the communities. Overall, our findings suggest that the abundance and composition of phages are related to effluent quality. Thus, there is a need for further research clarifying the association between phage dynamics and WWTP function.
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| 3. |
- Neth, Maria, 1980, et al.
(författare)
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A collaborative planning process to develop future scenarios for wastewater systems
- 2022
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 316
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Tidskriftsartikel (refereegranskat)abstract
- Wastewater infrastructure has a long lifetime and is subject to changing conditions and demands. When plans are made to upgrade or build new infrastructure, transdisciplinary planning processes and a robust analysis of future conditions are needed to make sustainable choices. Here, we provide a stepwise collaborative planning process in which future scenarios are developed together with local stakeholders and expert groups. The process was implemented at one of the largest wastewater treatment plants (WWTPs) in Scandinavia. With a combination of workshops and the use of a web-based digital tool, future scenarios including flows, pollutant loads, and treatment requirements could be created. Furthermore, sustainability prioritizations affecting the WWTP, were identified. The future scenarios developed for the WWTP in the case study, predict stricter and new regulations, constant or lower future loads and ambiguous future flows. The highest ranked sustainability priority was low resource and energy consumption together with low CO2 footprint. The quantified future scenarios developed in the planning process were used as input to a process model to show the consequences they would have on the WWTP in the case study. Applying this collaborative process revealed future scenarios with many, sometimes conflicting, expectations on future WWTPs. It also highlighted needs for improvements of both the collection system and the WWTP.
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| 4. |
- Parchami, Mohsen, et al.
(författare)
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MBR-Assisted VFAs production from excess sewage sludge and food waste slurry for sustainable wastewater treatment
- 2020
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- The significant amount of excess sewage sludge (ESS) generated on a daily basis by wastewater treatment plants (WWTPs) is mainly subjected to biogas production, as for other organic waste streams such as food waste slurry (FWS). However, these organic wastes can be further valorized by production of volatile fatty acids (VFAs) that have various applications such as the application as an external carbon source for the denitrification stage at a WWTP. In this study, an immersed membrane bioreactor set-up was proposed for the stable production and in situ recovery of clarified VFAs from ESS and FWS. The VFAs yields from ESS and FWS reached 0.38 and 0.34 gVFA/gVSadded, respectively, during a three-month operation period without pH control. The average flux during the stable VFAs production phase with the ESS was 5.53 L/m2/h while 16.18 L/m2/h was attained with FWS. Moreover, minimal flux deterioration was observed even during operation at maximum suspended solids concentration of 32 g/L, implying that the membrane bioreactors could potentially guarantee the required volumetric productivities. In addition, the techno-economic assessment of retrofitting the membrane-assisted VFAs production process in an actual WWTP estimated savings of up to 140 €/h for replacing 300 kg/h of methanol with VFAs. © 2020 by the authors.
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