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- 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. |
- 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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