| 1. |
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| 2. |
- Cimbritz, Michael, et al.
(författare)
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PAC dosing to an MBBR – Effects on adsorption of micropollutants, nitrification and microbial community
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 677, s. 571-579
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Tidskriftsartikel (refereegranskat)abstract
- Two nitrifying MBBR reactors were operated in parallel, one with PAC dosing and one without, to determine the effects of PAC dosing on nitrification and micropollutant adsorption in municipal wastewater. The removal of micropollutants was evaluated for several doses of PAC and batch experiments were performed to measure adsorption kinetics and nitrification rates. The influence of PAC on the nitrifying microbial community was examined by high-throughput amplicon sequencing. Long-term operation of the pilot reactors showed that nitrification could be maintained while supplying PAC at increasing doses, as confirmed by high nitrification rates and significant abundance of nitrifying bacteria. The adsorption of organic micropollutants could be controlled by the PAC dose, and increased dosing resulted in corresponding improvements in removal efficiency. Biomass, suspended or attached to carriers, did not interfere with the adsorption of organic micropollutants. Freundlich isotherms obtained from the batch experiments were used to predict removal of organic micropollutants in the pilot reactors, suggesting that batch adsorption experiments can be used to predict micropollutant removal on a full scale. Collectively, the results show that nitrification and adsorption of organic micropollutants can be performed simultaneously in an MBBR.
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| 3. |
- Edefell, Ellen, et al.
(författare)
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MBBRs as post-treatment to ozonation : Degradation of transformation products and ozone-resistant micropollutants
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 754
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Tidskriftsartikel (refereegranskat)abstract
- The degradation potential of micropollutants and transformation products in biological post-treatment after ozonation is partly unknown. A pilot plant with ozonation and subsequent biological treatment in a moving bed biofilm reactor (MBBR) was thus operated over 16 months to investigate the removal of micropollutants and the formation and removal of N-oxide transformation products. Lab-scale kinetic experiments were performed in parallel. At a moderate ozone dose of 0.5 g O3 g−1 DOC, further degradation of gabapentin and 3 iodinated contrast media (iomeprol, iopamidol, and iohexol) could be induced by the biofilm at prolonged exposure times. To facilitate comparison of feeding regimens in biofilm systems a new surface-related degradation rate constant was introduced. The availability of substrates in the pilot MBBR influenced the micropollutant degradation kinetics with increasing and decreasing degradation rates. N-oxides from erythromycin, clarithromycin, tramadol, and venlafaxine were formed during ozonation and could not be degraded by the biofilm.
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| 4. |
- Edefell, Ellen, et al.
(författare)
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Promoting the degradation of organic micropollutants in tertiary moving bed biofilm reactors by controlling growth and redox conditions
- 2021
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894. ; 414
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Tidskriftsartikel (refereegranskat)abstract
- A novel process configuration was designed to increase biofilm growth in tertiary moving bed biofilm reactors (MBBRs) by providing additional substrate from primary treated wastewater in a sidestream reactor under different redox conditions in order to improve micropollutant removal in MBBRs with low substrate availability. This novel recirculating MBBR was operated on pilot scale for 13 months, and a systematic increase was seen in the biomass concentration and the micropollutant degradation rates, compared to a tertiary MBBR without additional substrate. The degradation rates per unit carrier surface area increased in the order of ten times, and for certain micropollutants, such as atenolol, metoprolol, trimethoprim and roxithromycin, the degradation rates increased 20–60 times. Aerobic conditions were critical for maintaining high micropollutant degradation rates. With innovative MBBR configurations it may be possible to improve the biological degradation of organic micropollutants in wastewater. It is suggested that degradation rates be normalized to the carrier surface area, in favor of the biomass concentration, as this reflects the diffusion limitations of oxygen, and will facilitate the comparison of different biofilm systems.
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| 5. |
- El-taliawy, H., et al.
(författare)
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Ozonation efficiency in removing organic micro pollutants from wastewater with respect to hydraulic loading rates and different wastewaters
- 2017
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 325, s. 310-321
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Tidskriftsartikel (refereegranskat)abstract
- Organic micro pollutants can be removed from water by ozonation. In this article we studied the performance of ozonation under real life conditions and compared results of the same ozonation pilot plant installed at different wastewater treatment plants (WWTPs) thus operating with different waters. The comparability of the removal and reaction rate constants from one waste water treatment plant were low in respect to reaction rate, removal as well as to response to the specific ozone dose. Neither pH-value nor residual nitrite concentrations were the driving force considering these differences. Further tests with different loadings were conducted at the same WWTP under different weather conditions. For the different hydraulic loading of the biological plant, the ozonation was running with rather similar removal rates concerning the same specific (TOC normalized) ozone dose. The compounds that were removed quantitatively under dry weather were still removed well with three times dry weather flow. Using a dataset from one WWTP to optimize operation in another one is thus questionable.
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| 6. |
- Eriksson, Eva, 1973-, et al.
(författare)
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Biocides in urban wastewater treatment plant influent at dry and wet weather : concentrations, mass flows and possible sources
- 2014
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 60, s. 64-74
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, exterior thermal insulation systems became more and more important leading to an increasing amount of houses equipped with biocide-containing organic façade coatings or fungicide treated wood. It is known that these biocides, e.g. terbutryn, carbendazim, and diuron, as well as wood preservatives as propiconazole, leach out of the material through contact with wind driven rain. Hence, they are present in combined sewage during rain events in concentrations up to several hundred ng L(-1). The present study focused on the occurrence of these biocides in five wastewater treatment plants in Denmark and Sweden during dry and wet weather. It was discovered, that biocides are detectable not only during wet weather but also during dry weather when leaching from façade coatings can be excluded as source. In most cases, the concentrations during dry weather were in the same range as during wet weather (up to 100 ng L(-1)); however, for propiconazole noteworthy high concentrations were detected in one catchment (4.5 μg L(-1)). Time resolved sampling (12 × 2 h) enabled assessments about possible sources. The highest mass loads during wet weather were detected when the rain was heaviest (e.g. up to 116 mg h(-1) carbendazim or 73 mg h(-1) mecoprop) supporting the hypothesis that the biocides were washed off by wind driven rain. Contrary, the biocide emissions during dry weather were rather related to household activities than with emissions from buildings, i.e., emissions were highest during morning and evening hours (up to 50 mg h(-1)). Emissions during night were significantly lower than during daytime. Only for propiconazole a different emission behaviour during dry weather was observed: the mass load peaked in the late afternoon (3 g h(-1)) and declined slowly afterwards. Most likely this emission was caused by a point source, possibly from inappropriate cleaning of spray equipment for agriculture or gardening.
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| 7. |
- Fernández-Calviño, David, et al.
(författare)
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Ecotoxicological assessment of propiconazole using soil bacterial and fungal growth assays
- 2017
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 115, s. 27-30
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Tidskriftsartikel (refereegranskat)abstract
- Effects of the fungicide propiconazole on soil microorganisms were tested using [3H] leucine incorporation and [14C] acetate in ergosterol incorporation to measure bacterial and fungal growth inhibition, respectively. Growth was compared to basal respiration (BR) and substrate-induced respiration (SIR) in soil microcosms established according to the OECD 217 guideline. Fungal growth was most sensitive with IC50 values remaining around 300 mg kg−1 during 40 days of incubation. SIR was initially less sensitive (IC50 1300 mg kg−1), but IC50 values progressively decreased over time to reach 380 mg kg−1 after 40 days. Bacterial growth was affected at concentrations ≥200 mg kg−1, but exhibited more complex dose-response relationships possibly due to a combination of direct toxicity, bacterial community adaptation, and competitive release from the more severely affected fungi. BR was either stimulated or not affected by propiconazole. Our results indicate that group-specific endpoints targeting microbial growth will improve ecotoxicological assessment of toxicants for environmental risk assessment.
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| 8. |
- Fernández-Calviño, David, et al.
(författare)
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Isothiazolinone inhibition of soil microbial activity persists despite biocide dissipation
- 2023
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- Soil microbial growth and activity are generally assumed to recover rapidly after dissipation of organic toxicants. We studied the effects of four readily degradable isothiazolinone biocides (benzisothiazolinone, BIT; methylisothiazolinone, MIT; octylisothiazolinone, OIT; 4,5-dichloro-2-octyl-isothiazolinone, DCOIT) on bacterial growth, fungal growth, basal respiration, and substrate-induced respiration in controlled soil microcosm experiments. Bacterial growth followed by fungal growth were the two most sensitive endpoints during the first two days. Significant dissipation of biocides occurred within just 8 h and 94–100% had dissipated after 40 days except for DCOIT tested at a high concentration (50 mg kg−1, 54% remaining after 40 d). Despite biocide dissipation, all isothiazolinones inhibited bacterial growth for >7 days, whereas fungal growth and substrate-induced respiration were inhibited for up to 40 days. Bacterial growth recovery after 40 days was linked to development of bacterial community tolerance for DCOIT, but not for the other less persistent isothiazolinones. Our study is the first to report on toxic effects of isothiazolinones on soil microbial growth and demonstrates that inhibitory effects of isothiazolinones on soil microbial growth and activity (especially fungal growth and substrate-induced respiration) persisted even long after biocide dissipation, indicating “legacy effects” and retarded recovery of soil microbial functions. We propose that retarded recovery of fungal, relative to bacterial, growth may be a general phenomenon during the dissipation of toxicants in contaminated soils and that it may be explained by intrinsic differences between bacterial and fungal biology in soil and by competitive interactions between these two dominant groups of soil microbial decomposers.
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| 9. |
- Fernández-Calviño, David, et al.
(författare)
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Short-term toxicity assessment of a triazine herbicide (terbutryn) underestimates the sensitivity of soil microorganisms
- 2021
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 154
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the impacts of persistent triazine herbicides and biocides on soil microorganisms. Terbutryn toxicity in soil microorganisms was studied using bacterial and fungal growth, substrate induced respiration (SIR) and basal respiration as ecotoxicological end-points. In the short-term (0–7 days), increasing concentrations of terbutryn (0–800 mg kg−1) progressively inhibited bacterial and fungal growth by up to 33–36% (4 h) and 49–55% (7 days), whereas SIR and basal soil respiration remained unaffected. Following long-term (40 days) exposure to terbutryn, both bacterial and fungal growth were inhibited by up to 76–78%, and SIR was inhibited by up to 53%. Hence, our results unexpectedly demonstrate time-cumulative microbial growth inhibition over extended time periods in soil and indicate that current ecotoxicological guidelines may underestimate risks posed by chemicals to soil microorganisms.
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| 10. |
- Haghighatafshar, Salar, et al.
(författare)
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Microsieving coupled with O3 or ClO2 for treatment and disinfection of combined sewer overflows
- 2018
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; 74:3, s. 123-134
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Tidskriftsartikel (refereegranskat)abstract
- A compact combined sewer overflow (CSO) treatment unit is set up and evaluated in pilot-scale. The pilotplant consisted of flocculation, coagulation and a microsieving system followed by a disinfection unit with either O3 or ClO2. Efficiency of the pilot-plant was evaluated with respect to reduction of Escherichia coli, coliform bacteria and intestinal enterococci as well as removal of biocides. Results showed that 10 mg L-1 of ClO2 as disinfectant was sufficient to meet the European Union (EU) requirements as per Bathing Water Directive (2006/7 EC) while the same results were only achieved when higher O3 dose (20 mg O3 L-1) was applied. This study revealed that chlorine dioxide was the most effective disinfectant agent in reducing the number of bacteria to below the limits set by the EU Bathing Water Directive and that the pre-treatment used was highly efficient. Regarding biocides, the efficiency of the removal was highly dependent on the type of substance. However, ozone was found to be able to remove a broader range of the investigated biocides.
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