| 1. |
- Meng, Pingping, et al.
(författare)
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Efficient removal of perfluorooctane sulfonate from aqueous film-forming foam solution by aeration-foam collection
- 2018
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 203, s. 263-270
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous film-forming foams (AFFFs) used in fire-fighting are one of the main contamination sources of perfluorooctane sulfonate (PFOS) to the subterranean environment, requiring high costs for remediation. In this study, a method that combined aeration and foam collection was presented to remove PFOS from a commercially available AFFF solution. The method utilized the strong surfactant properties of PFOS that cause it to be highly enriched at air-water interfaces. With an aeration flow rate of 75 mL/min, PFOS removal percent reached 96% after 2 h, and the PFOS concentration in the collected foam was up to 6.5 mmol/L, beneficial for PFOS recovery and reuse. Increasing the aeration flow rate, ionic strength and concentration of co-existing surfactant, as well as decreasing the initial PFOS concentration, increased the removal percents of PFOS by increasing the foam volume, but reduced the enrichment of PFOS in the foams. With the assistance of a co-existing hydrocarbon surfactant, PFOS removal percent was above 99.9% after aeration-foam collection for 2 h and the enrichment factor exceeded 8400. Aeration-foam collection was less effective for short-chain perfluoroalkyl substances due to their relatively lower surface activity. Aeration-foam collection was found to be effective for the removal of high concentrations of PFOS from AFFF-contaminated wastewater, and the concentrated PFOS in the collected foam can be reused.
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| 2. |
- Meng, Pingping, et al.
(författare)
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Role of the air-water interface in removing perfluoroalkyl acids from drinking water by activated carbon treatment
- 2020
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 386
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Tidskriftsartikel (refereegranskat)abstract
- Contamination of drinking water by per- and polyfluoroalkyl substances (PFASs) is a worldwide problem. In this study, we for the first time revealed the role of the air-water interface in enhancing the removal of long-chain perfluoroalkyl carboxylic (PFCAs; CnF2n+1COOH, n >= 7) and perfluoroalkane sulfonic (PFSAs; CnF2n+1SO3H, n >= 6) acids, collectively termed as perfluoroalkyl acids (PFAAs), through combined aeration and adsorption on two kinds of activated carbon (AC). Aeration was shown to enhance the removal of long-chain PFAAs through adsorption at the air-water interface and subsequent adsorption of PFAA-enriched air bubbles to the AC. The removal of selected long-chain PFAAs was increased by 50-115 % with the assistance of aeration, depending on the perfluoroalkyl chain length. Aeration is more effective in enhancing long-chain PFAA removal as air-water interface adsorption increases with PFAA chain length due to higher surface activity. After removing adsorbed air bubbles by centrifugation, up to 80 % of the long-chain PFAAs were able to desorb from the sorbent, confirming the contribution of the air-water interface to the adsorption of PFAAs on AC. Aeration during AC treatment of water could enhance the removal of long-chain PFAAs, and improve the performance of AC during water treatment.
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| 3. |
- Mustafa, Majid, et al.
(författare)
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Identification of resistant pharmaceuticals in ozonation using QSAR modeling and their fate in electro-peroxone process
- 2021
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Ingår i: Frontiers of Environmental Science and Engineering. - : Higher Education Press. - 2095-2201 .- 2095-221X.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The abatements of 89 pharmaceuticals in secondary effluent by ozonation and the electro-peroxone (Eperoxone) process were investigated. Based on the results, a quantitative structure-activity relationship(QSAR) model was developed to explore relationship between chemical structure of pharmaceuticalsand their oxidation rates by ozone. The orthogonal projection to latent structure (OPLS) method wasused to identify relevant chemical descriptors of the pharmaceuticals, from large number ofdescriptors, for model development. The resulting QSAR model, based on 44 molecular descriptorsrelated to the ozone reactivity of the pharmaceuticals, showed high goodness of fit (R2 = 0.963) andpredictive power (Q2 = 0.84). After validation, the model was used to predict second-order rateconstants of 491 pharmaceuticals of special concern (kO3 ) including the 89 studied experimentally. The predicted kO3 values and experimentally determined pseudo-first order rate constants of thepharmaceuticals’ abatement during ozonation (kOZ) and the E-peroxone process (kEP) were then usedto assess effects of switching from ozonation to the E-peroxone process on removal of thesepharmaceuticals. The results indicate that the E-peroxone process could accelerate the abatement ofpharmaceuticals with relatively low ozone reactivity (kO3 < ~102 M–1.s–1) than ozonation (3–10 min versus 5–20 min). The validated QSAR model predicted 66 pharmaceuticals to be highly O3-resistant.The developed QSAR model may be used to estimate the ozone reactivity of pharmaceuticals ofdiverse chemistry and thus predict their fate in ozone-based processes.
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| 4. |
- Wang, Bin, et al.
(författare)
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A primary estimate of global PCDD/F release based on the quantity and quality of national economic and social activities
- 2016
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Ingår i: Chemosphere. - Oxford, United Kingdom : Elsevier. - 0045-6535 .- 1879-1298. ; 151, s. 303-309
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Tidskriftsartikel (refereegranskat)abstract
- The correlations between polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) releases and factors relevant to human social-economic activities (HSEAs) were analyzed. The multiple linear regression model was successfully developed to estimate the total global PCDD/F release. The PCDD/F releases significantly correlated with population, area, GDP and GNI, suggesting that "quantity" of HSEAs have significantly contributed to the PCDD/F releases. On another aspect, advanced technologies are usually adopted in developed countries/regions, and hence reduce the PCDD/F release. The significant correlation between PCDD/F release and CO2 emission implies the potential of simultaneous reduction of CO2 emission and PCDD/F release. The total global PCDD/F release from 196 countries/regions was estimated to be 100.4 kg-TEQ yr(-1). The estimated annual PCDD/F release per unit area ranged from 0.007 to 28 mg-TEQ km(-2). Asia is estimated to have the highest PCDD/F release of 47.1 kg-TEQ yr(-1), almost half of the total world release. Oceania is estimated to have the smallest total release but the largest per-capita release. For the developed areas, such as Europe and North America, the PCDD/F release per unit GDP is lower, while for Africa, it is much higher.
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| 5. |
- Wang, Huijiao, et al.
(författare)
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Oxidation of emerging biocides and antibiotics in wastewater by ozonation and the electro-peroxone process
- 2019
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 235, s. 575-585
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the abatement of a number of antimicrobials frequently detected in municipal wastewater by conventional ozonation and a recently developed ozone-based advanced oxidation process, the electro-peroxone (E-peroxone) process. A synthetic water and a real secondary wastewater effluent were spiked with fourteen antimicrobials, including antibiotics and biocides, and then treated by the two processes. The results show that most of the antibiotics investigated (e.g., ofloxacin, trimethoprim, norfloxacin, and ciprofloxacin) readily react with ozone (O3) and could therefore be efficiently eliminated from the water matrices by direct O3 oxidation during both processes. In contrast, most of the biocides tested in this study (e.g., clotrimazole, pentamidine, bixafen, propiconazole, and fluconazole) were only moderately reactive, or non-reactive, with O3. Therefore, these biocides were removed at considerably lower rate than the antibiotics during the two ozone-based processes, with hydroxyl radical (OH) oxidation playing an important role in their abatement mechanisms. When compared with conventional ozonation, the E-peroxone process is defined by the in situ electrogeneration of hydrogen peroxide, which considerably enhances the transformation of O3 to OH. As a result, the E-peroxone process significantly accelerated the abatement of biocides and required a considerably shorter treatment time to eliminate all of the tested compounds from the water matrices than conventional ozonation. In addition, the E-peroxone process enhanced the contributions of OH fractions to the abatement of moderately ozone reactive benzotriazoles. These results demonstrate that the E-peroxone process holds promise as an effective tertiary treatment option for enhancing the abatement of ozone-resistant antimicrobials in wastewater.
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| 6. |
- Du, Chenqiu, et al.
(författare)
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Grey image recognition-based mold growth assessment on the surface of typical building materials responding to dynamic thermal conditions
- 2023
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- Mold growth on building materials poses a threat to both the building structural integrity and occupants' well-being. However, it is generally studied under suitable conditions in laboratory; the assessment is based on visual inspection but lacks an objective criterion. This research explored the effects of simulated dynamic thermal conditions on mold growth on three typical building materials artificially contaminated with Aspergillus niger spores. Test specimens were assessed based on a developed digital image-based method, where image seg-mentation, processing, and greyscale recognition via the OpenCV visual library were introduced. The results showed that the high temperature-high humidity condition in a 24-h cyclic change facilitated mold growth on the surfaces of three materials, especially for gypsum board, with an identified area proportion of 1.13% on the 80th day. This was consistent with the changes of the counted number of mold colonies, and no significant differences were found among the gypsum board, latex paint, and wallpaper. The growth extents of mold spores were objectively evaluated by the mean greyscale values; the values decreased gradually with time, and the decrements were different compared high-temperature to low-temperature conditions. The mold growth models were developed, where the area proportion of mold growth was linearly related to the counted colonies and greyscale values under different material surfaces. This novel grey image recognition-based method provides an accurate means of evaluating mold growth abilities and extents, overcoming the inaccuracy of visual observa-tion. The findings have significant implications for visual inspection, mold prediction, and building management.
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| 7. |
- Wang, Yujue, et al.
(författare)
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Quantifying Uncertainties of Security and QoS for Design of Power Grid Communications Systems
- 2016
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Ingår i: 2016 49th Hawaii International Conference on System Sciences (HICSS). - : IEEE Computer Society. - 9780769556703 ; , s. 2566-2575
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Konferensbidrag (refereegranskat)abstract
- Reliable and secure communication, and high quality of service (QoS) (low latency, high availability, etc.) of data are critical to the successful operation of power systems. However, uncertainties, both aleatory and epistemic, are inherent to the system, which makes it difficult to secure the communication while fulfilling the QoS requirements. Nowadays, the administrators of the power grid's communication system have much flexibility in choosing a specific security scheme but the uncertainties make answering the question "what is the best scheme" or even "what is an adequate scheme" very difficult. Appropriately quantifying uncertainty and its effects on security is a key to choosing a sufficiently secure communication system for power grid while meeting QoS requirements. In this paper, we model aleatory and epistemic uncertainties using probability distributions and subjective logic respectively. Comprehensive quantification of the uncertainties can greatly sharpen administrators' understanding of the trade-offs between security and QoS and help them to select the most fitting security scheme to meet the QoS requirements. A case study demonstrates how our method works for two different application scenarios.
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| 8. |
- Yiming, Wu, 1987-, et al.
(författare)
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Adaptive Cyber-Security Scheme Incorporating QoS Requirements for WAMC Applications
- 2018
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Ingår i: Power Systems Computation Conference (PSCC2018). - : IEEE conference proceedings.
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Konferensbidrag (refereegranskat)abstract
- Smart Grid integrates power systems and communication systems to support intelligent control and operation applications. The inputs of those applications are normally measured data collected anywhere in the system and they are transmitted over Wide Area Networks (WAN). Challenges associated with Quality of Service (QoS) and cyber-security in the delivery of these data need to be addressed. In most research work in Smart Grid, QoS and cyber-security are considered separately. However, there is tension between the two: in order to maintain a certain level of QoS security might have to be compromised. The relationship is not, however, deterministic as both QoS and the performance of cyber-security countermeasures may vary over time. To address such challenges, this paper proposes a novel adaptive cyber-security scheme. It quantifies experts opinions of available cyber-security algorithms into a metric called security coverage. Then security coverage is adaptively optimized, by switching cyber-security algorithms, depending on observed data link QoS performance. The scheme is validated with simulation studies on a typical Wide Area Monitoring Control (WAMC) application, power oscillation damping control. The proposed adaptive cyber-security scheme is generally applicable to Smart Grid or power system applications that face varying communication performance during operation.
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