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- Hörsing, Maritha, 1970-, et al.
(författare)
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Effects of Temperature and Landfill Ageing on leaching and Degradation of Phtalates from a Poly(vinyl chloride) Carpet under Simulated Landfill Conditions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Phthalic ether esters are a group of chemicals used in the manufacture of PVC plastics, often as plasticizing additives, hence they may leach from the material and/or finished products before, during and after their use. This article presents results from laboratory-scale investigations of the fates of di-2-ethylhexyl phthalate (DEHP) and benzyl-butyl phthalate (BBP) under simulated landfill conditions, in custom-designed incubation units filled with model municipal solid waste. More specifically, the effects of temperature and landfill degradation phase on both the leaching and degradation potential of the two phthalates from a PVC carpet were examined, by measuring them in samples from units maintained at 20, 37, 55 and 70°C as they progressed through anaerobic acidogenic and methanogenic landfill phases. The results show that both BBP and DEHP leached from the carpet. For DEHP there was a clear temperature effect, and the highest losses were observed at 70°C, while for BBP slight increases in losses with temperature were observed from 20 to 55°C, and from 55 to 70°C, but the largest losses were seen at 37°C, probably due to biodegradation. Further degradation of the leached phthalates occured at all temperatures. Apparent degradation products observed included phthalic acid (PA) and mono (2-ethylhexyl)-, monobutyl- and monobenzyl-phthalate. In all cases the biological degradation of the phthalates occurred mainly after the systems switched to methanogenic conditions. The rate-limiting step of degradation in the 20 and 37°C units seemed to be the transformation of the monoesters, which tended to accumulate more than PA, while at 55 and 70°C PA accumulated to a higher extent.
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- Jonsson, Susanne, 1965-, et al.
(författare)
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Behaviour of mono- and diesters of o-phthalic acid in leachates released during digestion of municipal solid waste under landfill conditions
- 2003
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Ingår i: Advances in Environmental Research. - 1093-0191 .- 1093-7927. ; 7:2, s. 429-440
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Tidskriftsartikel (refereegranskat)abstract
- In order to investigate phthalates in landfill leachates, four landfill simulation reactors, filled with municipal solid waste from a housing area, were studied. Plasticised polyvinyl chloride (PVC) was added to two of the reactors. Two reactors, one with and one without the additional PVC, were aerated for 3 months to achieve methanogenic conditions. The other two became acidogenic a few days after filling and closing. After approximately 3 years, the acidogenic waste became methanogenic. The leachates were analysed for phthalic acid diesters and their degradation products, phthalic acid monoesters and o-phthalic acid. The occurrence of monobenzyl phthalate (MbenzP) and mono(2-ethylhexyl) phthalate (MEHP) showed that the diesters, butylbenzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP), released from the PVC products had been transformed, and that they were not completely sorbed to particles or to the waste material. Monoesters were observed once methanogenic conditions were established. The monoesters and phthalic acid were present in concentrations several orders of magnitude higher than the diesters themselves. Our results show that it is important to include monoesters in studies of the fate of diesters. To date, monoesters have been neglected in investigations of organic pollutants in landfill leachates.
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- Jonsson, Susanne, 1965-, et al.
(författare)
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Mono- and diesters from o-phthalic acid in leachates from different European landfills
- 2003
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Ingår i: Water Research. - 0043-1354 .- 1879-2448. ; 37:3, s. 609-617
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Tidskriftsartikel (refereegranskat)abstract
- Leachates from 17 different landfills in Europe were analysed with respect to phthalates, i.e. phthalic acid diesters (PAEs) and their degradation products phthalic acid monoesters (PMEs) and ortho-phthalic acid (PA). Diesters are ubiquitous and the human possible exposure and potential to human health and environment has put them in focus. The aim of this study was to elucidate whether monoesters and phthalic acid could be traced in landfill leachates and in what concentrations they may be found. The results showed that phthalates were present in the majority of the leachates investigated. The monoesters appeared from 1 to 20 μg/L and phthalic acid 2–880 μg/L (one divergent value of 19 mg phthalic acid/L). Their parental diesters were observed from 1 to 460 μg/L. These observed occurrences of degradation products, of all diesters studied, support that they are degraded under the landfill conditions covered by this study. Thus, we have presented strong evidences to conclude that microorganisms in landfills degrade diesters released from formulations in a variety of products, including polyvinyl chloride (PVC) species.
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- Jonsson, Susanne, 1965-, et al.
(författare)
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Transformation of phthalates in young landfill cells
- 2003
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 641-651
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Tidskriftsartikel (refereegranskat)abstract
- Phthalic acid diesters are additives in a variety of materials that can end up in landfills. Leachates from a series of full-scale young landfill cells were analysed over time for dimethyl, diethyl, dibutyl, butylbenzyl, and di(2-ethylhexyl) phthalate (respectively designated DMP, DEP, DBP, BBP, and DEHP), and their corresponding monoesters monomethyl, monoethyl, monobutyl, monobenzyl, and mono(2-ethylhexyl) phthalate (MMP, MEP, MbutP, MbenzP, and MEHP, respectively), as well as o-phthalic acid (PA). One landfill cell was created in each of three consecutive years by deposition of the same type of waste in July and August. The pH, volatile fatty acids (VFAs), and total organic carbon (TOC) were measured to characterise development of the degradation phases in three landfill cells, which revealed early acidogenic to initial methanogenic stages. Analysis of the phthalate compounds showed that observed concentrations of the degradation products were below the detection limit in the acidogenic leachates but exceeded concentrations of their corresponding diesters in leachates from cells in the initial methanogenic phase. Maximum and average concentrations of phthalic acid were 50 and 23 mg/l, respectively, and the corresponding values for the other phthalates were 430 and 27 ╡g/l. The concentrations of all phthalates decreased during the establishment of stable methanogenic conditions. ⌐ 2003 Elsevier Ltd. All rights reserved.
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| 7. |
- Magnusson, Björn, et al.
(författare)
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Combining high-rate aerobic wastewater treatment with anaerobic digestion of waste activated sludge at a pulp and paper mill
- 2018
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 77:8, s. 2068-2076
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Tidskriftsartikel (refereegranskat)abstract
- The activated sludge process within the pulp and paper industry is generally run to minimize the production of waste activated sludge (WAS), leading to high electricity costs from aeration and relatively large basin volumes. In this study, a pilot-scale activated sludge process was run to evaluate the concept of treating the wastewater at high rate with a low sludge age. Two 150 L containers were used, one for aeration and one for sedimentation and sludge return. The hydraulic retention time was decreased from 24 hours to 7 hours, and the sludge age was lowered from 12 days to 2–4 days. The methane potential of the WAS was evaluated using batch tests, as well as continuous anaerobic digestion (AD) in 4 L reactors in mesophilic and thermophilic conditions. Wastewater treatment capacity was increased almost four-fold at maintained degradation efficiency. The lower sludge age greatly improved the methane potential of the WAS in batch tests, reaching 170 NmL CH4/g VS at a sludge age of 2 days. In addition, the continuous AD showed a higher methane production at thermophilic conditions. Thus, the combination of high-rate wastewater treatment and AD of WAS is a promising option for the pulp and paper industry.
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- Ometto, Francesco, 1985-, et al.
(författare)
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Anaerobic digestion: an engineered biological process
- 2019
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Ingår i: Substitute natural gas from waste: technical assessment and industrial applications of biochemical and thermochemical processes. - London : Elsevier. - 012815554X - 9780128155547 - 9780128156445 ; , s. 63-74
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Bokkapitel (refereegranskat)abstract
- Anaerobic digestion (AD) is a biological process where a variety of microorganisms are the key factors for transforming complex organic structure into biogas, a mixture of methane, carbon dioxide, and other trace gases. Linked to the production of biogas is also the unique possibility to utilize and recycle nutrients released during the digestion. This gives the AD-process a key role in the development of many biorefinery concepts supporting industrial symbiosis and circular economy. The overall process efficiency is linked to the microbial steps which are affected by regulating factors including the characteristic of the substrate and the engineered process layout, together with the targeted outputs (raw biogas, compressed/liquid biogas, fertilizer, and/or other refined products). Between the digestion steps, the hydrolysis, the first microbial step, is often the rate-limiting step in degradation of polymeric substrates. As such, securing efficient and cost-effective hydrolysis represents today the key to process complex biomasses not yet fully utilized within the AD despite its high methane potential.
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| 9. |
- Ometto, F., et al.
(författare)
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Inclusion of Saccharina latissima in conventional anaerobic digestion systems
- 2018
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Ingår i: Environmental technology. - : Taylor & Francis. - 0959-3330 .- 1479-487X. ; 39:5, s. 628-639
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Tidskriftsartikel (refereegranskat)abstract
- Loading macroalgae into existing anaerobic digestion (AD) plants allows us to overcome challenges such as low digestion efficiencies, trace elements limitation, excessive salinity levels and accumulation of volatile fatty acids (VFAs), observed while digesting algae as a single substrate. In this work, the co-digestion of the brown macroalgae Saccharina latissima with mixed municipal wastewater sludge (WWS) was investigated in mesophilic and thermophilic conditions. The hydraulic retention time (HRT) and the organic loading rate (OLR) were fixed at 19 days and 2.1 g l-1 d-1of volatile solids (VS), respectively. Initially, WWS was digested alone. Subsequently, a percentage of the total OLR (20%, 50% and finally 80%) was replaced by S. latissima biomass. Optimal digestion conditions were observed at medium-low algae loading (=50% of total OLR) with an average methane yield close to [Formula: see text] and [Formula: see text] in mesophilic and thermophilic conditions, respectively. The conductivity values increased with the algae loading without inhibiting the digestion process. The viscosities of the reactor sludges revealed decreasing values with reduced WWS loading at both temperatures, enhancing mixing properties.
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| 10. |
- Safaric, Luka, 1988-, et al.
(författare)
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A Comparative Study of Biogas Reactor Fluid Rheology : Implications for Mixing Profile and Power Demand
- 2019
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Ingår i: Processes. - Basel, Switzerland : MDPI. - 2227-9717. ; 7:10
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion (AD) is an established process for integrating waste management with renewable energy and nutrient recovery. Much of the research in this field focuses on the utilisation of new substrates, yet their effects on operational aspects such as fluid behaviour and power requirement for mixing are commonly overlooked, despite their importance for process optimisation. This study analysed rheological characteristics of samples from 21 laboratory-scale continuous stirred-tank biogas reactors (CSTBRs) digesting a range of substrates, in order to evaluate substrate effect on mixing efficiency and power demand through computational fluid dynamics (CFD). The results show that substrate and process parameters, such as solids content and organic loading, all have a significant effect on CSTBR fluid rheology. The correlation levels between rheological and process parameters were different across substrates, while no specific fluid behaviour patterns could be associated with substrate choice. Substrate should thus be considered an equally important rheology effector as process parameters. Additional substrate-related parameters should be identified to explain the differences in correlations between rheological and process parameters across substrate groups. The CFD modelling revealed that the rheology differences among the AD processes have significant implications for mixing efficiency and power demand of the CSTBRs, highlighting the importance of considering the substrate-induced effects on CSTBR rheology before including a new substrate.
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