Scenario analysis: a review of methods and applications for engineering and environmental systems

Changing environment, uncertain economic conditions, and socio-political unrest have renewed interest in scenario analysis, both from theoretical and applied points of view. Nevertheless, neither the processes for scenario analysis (SA) nor evaluation criteria and metrics have been regularized. In this paper, SA-reported applications and implementation methodology are discussed in the context of an extensive literature review covering papers published between 2000 and 2010. Over 340 papers were identified through a series of queries in the web of science database. The papers were classified based on the North American Industrial Classification System and SA application goals (environmental, business, and social). SA methodology used in each paper was assessed based on four main criteria: coverage, consistency, uncertainty assessment, and efficiency. We find a significant increase in SA applications, especially in the environmental field. Theoretical developments in the field represent a small fraction of published studies and do not increase in time. The methods used to develop different scenarios vary widely across the academic literature and applications reviewed. Similarly, the methods and data used to characterize the scenarios and develop response strategies are extremely diverse and are limited by factors such as computational tractability and available time and resources. Based on this review, we recommend a regular process for scenario analysis that includes the steps of analysis, scenario definition, and evaluation.     

Heavy metal phytoextraction—natural and EDTA-assisted remediation of contaminated calcareous soils by sorghum and oat

The abilities of sorghum (Sorghum bicolor L.) and oat (Avena sativa L.) to take up heavy metals from soils amended with ethylenediaminetetraacetic acid (EDTA) were assessed under greenhouse conditions. Both plants were grown in two soils contaminated with heavy metals (Gujranwala—silty loam and Pacca—clay loam). The soils were treated with 0, 0.625, 1.25, and 2.5 mM EDTA kg^?1 soil applied at both 45 and 60 days after sowing (DAS); the experiment was terminated at 75 DAS. Addition of EDTA significantly increased concentrations of Cd, Cr, and Pb in roots and shoots, and bio-concentration factors and phytoextraction rates were also increased. Post-harvest soil analysis showed that soluble fractions of metals were also increased significantly. The increase in Cd was ≈ 3-fold and Pb was ≈ 15-fold at the highest addition of EDTA in Gujranwala soil; in the Pacca soil, the increase was less. Similarly, other phytoremediation factors, such as metal translocation, bio-concentration factor, and phytoextraction, efficiency were also maximum when soils were treated with 2.5 mM EDTA kg^?1 soil. The study demonstrated that sorghum was better than oat for phytoremediation.     

Fabrication of cerium titanate cellulose fiber nanocomposite materials for the removal of methyl orange and methylene blue from polluted water by photocatalytic degradation

In this study, cellulose fibers (Cf), extracted from sunflower seed husk, and different molar ratios of cerium titanate (Ce-Ti) NPs were prepared from sunflower seed husk extract by a green biosynthesis approach. Cf and Ce-Ti NPs were reacted via cross-linking reaction to synthesize a novel nanocomposite photocatalyst of Ce-Ti/Cf. Using Fourier-transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM-EDX) spectroscopy, all manufactured materials were characterized. The results obtained from FTIR and EDX analyses indicated that Cf and its nanocomposites (0.1 Ce-Ti/Cf, 0.3 Ce-Ti/Cf, and 0.5 Ce-Ti/Cf) were successfully prepared by harnessing biomass extract from sunflower seed husk. Furthermore, XRD revealed that the degree of crystallinity of the nanocomposites was enhanced by increasing the molar ratios of the Ce-Ti NPs. The photocatalytic activity of as-fabricated 0.1 Ce-Ti/Cf, 0.3 Ce-Ti/Cf, and 0.5 Ce-Ti/Cf nanocomposite samples was investigated on methylene blue (MB) and methyl orange (MO) dyes as model organic compounds found in wastewaters. The effects of dose, contact time, and pH on the photocatalytic activity of the synthesized nanocomposites, the photodegradation kinetic parameters of MB, and MO degradation with/without the addition of H₂O₂ were also studied. The results revealed that high photodegradation efficiency could be obtained as the ratio of TiO₂ in the Ce-Ti nanocomposite formula increases. Moreover, after sunlight irradiation, the adsorption capacity and the dye decomposition ratio significantly increase during the early contact time and reach equilibrium at about 240 and 120 min for 0.5 Ce-Ti/Cf nanocomposite photocatalyst in the absence and presence of hydrogen peroxide, respectively. In light of the obtained results and the practical wastewater treatment study conducted, the prepared photocatalyst from Ce-Ti/Cf nanocomposites could be a promising material for treating dye wastewater especially collected from Egypt.