| 1. |
- 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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| 2. |
- Ossiansson, Elin, 1983, et al.
(författare)
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Primary filtration of municipal wastewater with sludge fermentation – Impacts on biological nutrient removal
- 2023
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 902
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Tidskriftsartikel (refereegranskat)abstract
- Primary filtration is a compact pre-treatment process for municipal wastewater, which can lead to high removal of total suspended solids (TSS) if polymer is added prior to filtration. Extensive carbon removal with rotating belt filter (RBF) can be combined with filter primary sludge fermentation at ambient temperature, in order to produce volatile fatty acids (VFAs) as carbon source for biological nutrient removal (BNR). This process was implemented at large pilot-scale and operated for more than a year. The results showed that the RBF efficiently removed particles >10 μm, and that the TSS removal had a strong linear correlation to the influent TSS concentration. Fermentation of the sludge at ambient temperature and five days retention time and addition of the fermentate to the wastewater could nearly double the VFA concentration in the wastewater by adding 31 ± 9 mg VFA-COD/L. Meanwhile, an increase of 2 mg/L of ammonium nitrogen, and 0.7 mg /L of phosphate phosphorus would be added to the wastewater with the fermentate. Adding the fermented sludge to the wastewater stream and removing the particles with RBF makes it possible to utilize nearly all the produced VFAs for BNR, and the feasibility of this configuration was shown at pilot-scale. According to simulations of subsequent BNR, the pre-treatment would lead to lower effluent total nitrogen concentrations. Alternatively, the required BNR volume could be reduced by 11–18 %. The estimated total biogas production was similar for pre-treatment with primary settler and RBF with fermentation. RBF without fermentation gave the most favourable energy balance, but did not reach the same low effluent value for total nitrogen as RBF with fermentation.
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| 3. |
- Ossiansson, Elin, 1983, et al.
(författare)
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Seasonal variations in acidogenic fermentation of filter primary sludge
- 2023
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Ingår i: Water Research. - 0043-1354 .- 1879-2448. ; 242
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Tidskriftsartikel (refereegranskat)abstract
- Primary treatment of municipal wastewater by rotating belt filtration followed by hydrolysis and acidogenic fermentation of the filter primary sludge (FPS) at ambient temperature was studied at pilot-scale during one year. The seasonal variations of volatile fatty acids (VFAs), nutrient release and soluble COD production as well as microbial community assembly were assessed, leading to novel findings for fermentation at ambient temperature. The reproducibility of VFA production performance was first established by operating the two fermentation reactors under the same conditions, showing similar results regarding VFA production and microbial community structure. One year of operation at 5 d retention time (RT) and 16–29 °C resulted in an average VFA yield of 180±35 mg COD/g VSin and soluble COD yield of 242±40 mg COD/g VSin. The VFA formation was temperature-dependent, with ϴ=1.033±0.005 (r=r20·Θ(T−20∘C)). The seasonal variations of the acetic and propionic acid productions were pronounced, whereas the productions of VFAs with longer chains were more stable regardless of temperature. The community structure of the reactor microbiomes was also clearly affected by season and temperature and linked with the production spectrum of VFAs. The ammonium and phosphate releases were stable during the year, leading to a decrease in ratios of soluble COD to NH4+-N and PO43−-P during winter. The soluble COD yield was 11% and 27% higher at 5 d RT compared to 3 and 2 d RT respectively, but the corresponding volumetric productivities were lower. The dissimilarities between microbiomes in influent FPS and fermenters were significant even at a short RT of 2 d, and increased with longer RT of 3 and 5 d, primarily caused by selection of bacteria within Bacteroidota in the fermentation reactors.
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