| 1. |
- Ahrens, Lutz
(author)
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Exploring the adsorption of short and long chain per- and polyfluoroalkyl substances (PFAS) to different zeolites using environmental samples
- 2023
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In: Environmental Science: Water Research & Technology. - 2053-1400 .- 2053-1419.
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Journal article (peer-reviewed)abstract
- Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants that are gaining attention for their ubiquitous distribution, persistence, and toxicity in the environment and ecosystem. Among the PFAS removal techniques from water, adsorption treatment techniques are considered most promising. In this study for the first time, 9 different zeolites and powdered activated carbon (PAC) were tested for 18 PFAS including C-3-C-13 perfluoroalkyl carboxylates acids (PFCAs), C-4, C-6, C-8 perfluoroalkane sulfonates (PFSA), three fluorotelomer sulfonate (FTSAs), and perfluorooctane sulfonamide (FOSA) in batch sorption experiments using ultrapure and real environmental water samples. Adsorption experiments showed that zeolite beta with SAR = 25 (silica alumina ratio, SiO2/Al2O3) (99.5% n-ary sumation PFAS uptake) and SAR = 300 (99.2% n-ary sumation PFAS uptake), and mordenite with SAR = 240 (87.8% n-ary sumation PFAS uptake) were the most promising adsorbent media. Sorption of individual PFAS depended on the perfluoroalkyl chain length, functional group and molecule size. Overall, AgY390 and AgY760 silver (Ag) functionalized zeolites (76.4% and 78.3% n-ary sumation PFAS uptake respectively) showed better uptake capacity for PFAS compared to the as-synthetized Y390 and Y760 (68.6% and 68.3% n-ary sumation PFAS uptake respectively), and could favor catalytic reactions in PFAS degradation. PFAS sorption to PFAS-fortified real contaminated water samples was as follows: Beta25 (99.4%) < Beta360 (97.5%) < MOR (97.1%) < Y760 (95.5%) < CHA (71.4%) (with respect to PAC 99.9%). X-ray structural data revealed that changes in unit cell parameters arise from channel distortions caused by the encapsulation of PFAS inside the zeolites cages. Thermal analyses corroborate these results and revealed degradation of the perfluoroalkyl chain and expulsion upon heating are accompanied by exothermic reactions registered in the differential thermal analysis (DTA). The features of the zeolites, including the specific surface area, pores size and distribution, SAR, temperature, presence of extraframework cations and polarity significantly affected their PFAS adsorption capacity.
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| 2. |
- Furén, Robert, Industridoktorand, et al.
(author)
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Concentration, distribution, and fractionation of metals in the filter material of 29 bioretention facilities: a field study
- 2023
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In: Environmental Science. - : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; 9:12, s. 3158-3173
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Journal article (peer-reviewed)abstract
- Pollutant loads stemming from anthropogenic activities conveyed in urban stormwater runoff contribute to the impairment of downstream water bodies. Cities and municipalities are increasingly turning toward green infrastructure stormwater control measures to treat pollutants at the source of runoff. One example of these technologies is bioretention, which is commonly applied for stormwater treatment in urban areas due to its demonstrated effectiveness in removing various pollutants from water, including sediment, nutrients (e.g., N and P), and metals. As metals are mainly removed by filtration or adsorption to soil particles, the filter media is important for metal removal in bioretention. However, the capacity to remove metals through adsorption by bioretention media is finite; thus, the media may need to be replaced and disposed of after maintenance or at the end of its operational lifespan. Pollutant accumulation in bioretention media has the potential to approach toxicity thresholds, which may introduce complexities for safe handling and disposal. To fully capture the potential challenges associated with metals accumulation in media over time, it is important to understand the accumulation processes and mobility of metals in bioretention facilities as they age. Although several studies have investigated metal accumulation and distribution in bioretention media, few have assessed metal mobility by fractionation using sequential extraction methods in older (i.e., >7 years) facilities. In November 2019, we conducted a comprehensive field study of older facilities in Ohio, Michigan, and Kentucky (USA) to improve the understanding of the accumulation processes and metal mobility in bioretention. In this study, concentrations of several metals (i.e., Cr, Cu, Ni, Pb, and Zn) were analyzed in samples of filter material from 29 bioretention sites in operation for 7–16 years. Except for Cd, all metals were found in all samples. Metals accumulation was clear with highest concentrations found in the top (0–5 cm) layer of the filter material, attributable to the filtration of particles percolating through the media profile. Lower concentrations were observed in deeper (i.e., >10 cm) layers of the bioretention media. The fractionation showed that the metals of interest were present at high levels with a risk of leaching over time, among which Cd, Zn, and Pb were suggested to be mobile from the filter material during precipitation. Thus, there is a potential risk of leakage from filter material or sediment removed from biofilters, e.g., during maintenance and disposal. The results of principal component analysis indicated specifically correlations between metal concentrations and the filter material soil texture including the organic matter content. These results contribute to improved design and operation and suggest regular maintenance to reduce long-term risks associated with the accumulation of metals in bioretention and similar urban stormwater treatment facilities. Since most metals are trapped in the top layer of the filter it may be enough to remove only the top layer. However, metal fractionation should be considered when handling the material.
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| 3. |
- Mantovani, Sebastiano, et al.
(author)
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Amino acid-driven adsorption of emerging contaminants in water by modified graphene oxide nanosheets
- 2023
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In: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 9:4, s. 1030-1040
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Journal article (peer-reviewed)abstract
- Graphene oxide nanosheets have shown promising adsorption properties toward emerging organic contaminants in drinking water. Here, we report a family of graphene oxide nanosheets covalently modified with amino acids and the study on their adsorption properties toward a mixture of selected contaminants, including pharmaceuticals, additives, and dyes. Graphene oxides modified with l-glutamic acid and l-methionine (GO-Glu and GO-Met) were synthesized and purified with a scalable and fast synthetic and purification procedure, and their structure was studied by combined X-ray photoelectron spectroscopy and elemental analysis. An amino acid loading of about 5% and a slight reduction (from 27% down to 14-20% oxygen) were found and associated with the adsorption selectivity. They were compared to unmodified GO, reduced GO (rGO), GO-lysine, and to the reference sample GO-NaOH. Each type of modified GO possesses a higher adsorption capacity toward bisphenol A (BPA), benzophenone-4 (BP4), and carbamazepine (CBZ) than standard GO and rGO, and the adsorption occurred within the first hour of contact time. The maximum adsorption capacity (estimated from the adsorption isotherms) was strictly related to the amino acid loading. Accordingly, molecular dynamics simulations highlighted higher interaction energies for the modified GOs than unmodified GO, as a result of higher van der Waals and hydrophobic interactions between the contaminants and the amino acid side chains on the nanosheet surface.
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| 4. |
- Odhiambo, Michael, 1984, et al.
(author)
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Health risks due to intrusion into the drinking water distribution network : hydraulic modelling and quantitative microbial risk assessment
- 2023
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In: Environmental Science. - : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; 9:6, s. 1701-1716
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Journal article (peer-reviewed)abstract
- Ageing water infrastructure is prone to increased physical deficiencies. These form pathways for pathogen intrusion into drinking water distribution networks (WDNs), hence posing major health risks to consumers. This study aimed at estimating the risk of infection from pipe breaks and intermittent water supply, which are some of the major causes of sustained low pressure within the WDN and hence the triggers for pathogen intrusion. Further, the effect of groundwater level on pathogen intrusion was investigated. Three risk scenarios were evaluated on the example of a real WDN in Sweden: (i) pipe break with no intrusion from leak holes, (ii) pipe break with intrusion due to leak holes, and (iii) insufficient water supply in the presence of leak holes. Pressure distribution from hydraulic modelling, estimated groundwater levels, and pathogen concentration in intruding water (from field study) were used to estimate the intrusion and the number of pathogens entering the WDN. Reference pathogens Campylobacter, Cryptosporidium, and norovirus were used in quantitative microbial risk assessment (QMRA) for assessing the health risks. Results indicated that the daily probability of infection exceeded an acceptable target value of 10−6 for most of the WDN and for all scenarios. The findings were consistent with the estimated annual burden of acute gastrointestinal illness in Sweden. The concentration of pathogens in intruding water and the duration of the low-pressure-causing event were observed to influence the probability of infection the most. The results from this study can be used to identify vulnerable sections in the WDN, which can be targeted for additional investment in monitoring and/or renewal.
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| 5. |
- Parvage, Mohammed Masud, et al.
(author)
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Sequential removal of nitrate and sulfate in woodchip and hematite : coated biochar bioreactor
- 2023
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In: Environmental Science. - : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; 9:2, s. 489-499
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Journal article (peer-reviewed)abstract
- Laboratory column experiments have been used to study the sequential removal of nitrate (NO3−) and sulfate (SO42−) from mine water, where NO3− was removed through denitrification and SO42− was removed through SO42− reduction and the subsequent precipitation of hydrogen sulfide (H2S) in a hematite-coated biochar (HCB) bioreactor. Denitrification and SO42− reduction were investigated in columns filled with pine woodchips and pine woodchips + biochar, both with and without the addition of lactate. Experimental results indicated that a >90% NO3− removal from 50 mg L−1 NO3−-N was achieved at a hydraulic residence time of 5 days without lactate addition, but that SO42− reduction was minimal after an initial startup period. Lactate was added to stimulate SO42− reduction, producing H2S with >90% SO42− removal from an initial concentration of 361 mg L−1 SO42−-S. Sulfate concentrations were reduced to a greater extent in the woodchip + biochar column, and NH4+ production was enhanced in both columns after lactate addition. After treatment in the HCB columns, H2S and NH4+ were removed to >95%. X-ray photoelectron spectroscopy (XPS) indicated that S2−, S22−, S0 and NH4+ were accumulating in the HCB columns and surface-bound iron was converted from Fe(III) to Fe(II). The XPS results suggested that the reductive dissolution of hematite preceded the precipitation of H2S as FeS, pyrite and elemental sulfur on the HCB surfaces.
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| 6. |
- Vezzaro, Luca, et al.
(author)
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Urban stormwater management
- 2023
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In: Environmental Science. - : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; 9:12, s. 3091-3093
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Journal article (other academic/artistic)
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| 7. |
- Vinnerås, Björn
(author)
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Resource recovery technologies as microbial risk barriers: towards safe use of excreta in agriculture based on hazard analysis and critical control point
- 2023
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In: Environmental Science: Water Research & Technology. - : Royal Society of Chemistry (RSC). - 2053-1400 .- 2053-1419. ; 9, s. 1008–1029-
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Journal article (peer-reviewed)abstract
- Agricultural use of human excreta contributes to sustainable nutrient resource management. In contrast, resource recovery from human excreta is associated with the risk of infection by pathogenic microorganisms. The microbial risk associated with human excreta needs to be properly managed. Pathogen inactivation efficacy of resource recovery technologies should be evaluated so that individual resource recovery processes can be monitored as health risk barriers. To this end, we reviewed the sanitization potential of resource recovery technologies from human excreta and identified the monitoring parameters of hazard analysis and critical control point (HACCP). We describe the inactivation of surrogate microorganisms in selected technologies in terms of the physicochemical conditions of matrices, different tolerances among surrogate microorganisms, and inactivation mechanisms. The estimated storage/operating time required to achieve the target log reduction values (LRVs) is shortened in thermal processes such as thermophilic storage, drying, composting, microwaving, and thermophilic digestion. In most processes, phage and helminth eggs were found to be appropriate indicators for conservative estimation. Finally, we argue that sanitization is congruent with decomposition of readily degradable organic matter and resource recovery. The barrier efficacy of resource recovery technologies should be validated using a pathogen inactivation kinetics model so that the exposure risk to infectious pathogens is sufficiently reduced through a reasonable combination of non-treatment and non-technical health risk barriers.
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