This work is not a product of the U.S. Government or the U.S. environmental Protection Agency, and the author is not doing this work in any governmental capacity. This research was not performed or funded by EPA and w...
The photo-oxidative dissolution of cadmium sulfide has been investigated in the presence of several complexing organic and inorganic compounds under oxygen-saturated conditions. At pH 4 and 7, aromatic organic ligands...
The photo-oxidative dissolution of cadmium sulfide has been investigated in the presence of several complexing organic and inorganic compounds under oxygen-saturated conditions. At pH 4 and 7, aromatic organic ligands enhance the cadmium dissolution rate by a factor of 5–6 over that without the organic present; EDTA, NTA, and citric and oxalic acids have little effect. Sulfite and hydrogen sulfide/bisulfide slightly enhance the dissolution. Conversely, at pH 10, EDTA and NTA produce a significant increase in dissolved cadmium (factor of approximately 18) while the other compounds exert little effect. These phenomena are explained by ligand surface complexation, and both surface and homogeneous ligand-enhanced dissolution.
This study examined the feasibility of using the grey wolf optimizer(GWO)and artificial neural network(ANN)to predict the compressive strength(CS)of self-compacting concrete(SCC).The ANN-GWO model was created using 11...
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This study examined the feasibility of using the grey wolf optimizer(GWO)and artificial neural network(ANN)to predict the compressive strength(CS)of self-compacting concrete(SCC).The ANN-GWO model was created using 115 samples from different sources,taking into account nine key SCC *** validation of the proposed model was evaluated via six indices,including correlation coefficient(R),mean squared error,mean absolute error(MAE),IA,Slope,and mean absolute percentage *** addition,the importance of the parameters affecting the CS of SCC was investigated utilizing partial dependence *** results proved that the proposed ANN-GWO algorithm is a reliable predictor for SCC’s *** that,an examination of the parameters impacting the CS of SCC was provided.
Operational strategies have been applied in constructed wetlands to optimize the removal of nutrients and hormones that are still a concern in wastewater treatment. The strategy of intensifying intermittent aeration w...
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Operational strategies have been applied in constructed wetlands to optimize the removal of nutrients and hormones that are still a concern in wastewater treatment. The strategy of intensifying intermittent aeration was investigated in two microcosm-scale vertical-flow constructed wetlands (VFCWs) planted with Eichhornia crassipes onto autoclaved aerated concrete (AC) in the removal of nutrients, estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2). CW-1 (2.4 LO2 min−1) and CW-2 (1.4 LO2 min−1) were fed with synthetic wastewater in sequencing-batch mode (cycles 48-48-72 h) and intermittently aerated for 1 h, followed by 7 h without aeration for 377 days. Combined with the intensification strategy, the use of planted free-floating macrophytes and concrete-based material (emergent) as filtering media stand out as the innovation and originality aspects of this study. Despite the hormone addition, intensifying aeration enhanced the efficiencies since CW-1 achieved the highest removals with 91% COD, 77% TN, 74% TAN, 60% nitrate, and 97% TP in Stage I (no hormone addition) and 90% COD, 80% TN, 93% TAN, 63% nitrate, and 82% TP in Stage II (with hormone addition). CW-1 achieved the highest removal efficiencies of E1 (84%), E2 (95%), and EE2 (73%). Conversely, the efficiencies decreased under the lower aeration rate (in CW-2) for all parameters. Macrophyte uptake and adsorption stood out for TN (>60.25%) and TP (>27.6%) removal as the main mechanisms in the VFCWs. The characteristics of AC favored ion exchange and precipitation, reinforcing the potential of this material as filtering media in VFCWs. Intensification of intermittent aeration combined with hormone addition diverse and riched the microbial community with the presence of Thauera, Lentimicrobium (denitrification), Candidatus Accumulibacter (phosphorus removal), Pseudomonas, Fusibacter, and Azoarcus (EE2 degradation). Intensifying intermittent aeration was an important strategy to enhance the simultaneou
Concrete carbonation resistance is essential for ensuring durability and extending the service life of concrete structures, as carbonation can lead to the degradation of reinforcing steel and compromised structural in...
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Precipitation was collected and chemically analyzed for a 1 yr period at four sites in western Washington. Spatial and seasonal variabilities in concentrations were identified with the highest concentrations nearest e...
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Precipitation was collected and chemically analyzed for a 1 yr period at four sites in western Washington. Spatial and seasonal variabilities in concentrations were identified with the highest concentrations nearest emission sources and in the summer. Multiple correlations among measured species revealed five groupings which were interpreted as the influences of seasalt, metals from a Cu smelter, an urban factor, soil, and acidic sulfate aerosol. A simple washout model predicted that the Cu smelter was the major contributor to a budget for rainwater sulfate. Measurement uncertainties were estimated for each analyte.
The status of fundamental models of the performance of deep bed filters is reviewed and a modified model for monodisperse suspensions is presented. Particle removal is described by a modified version of the Vigneswara...
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The status of fundamental models of the performance of deep bed filters is reviewed and a modified model for monodisperse suspensions is presented. Particle removal is described by a modified version of the Vigneswaran and Tulachan model for the complete cycle of transient filter performance. A modification of the O'Melia and Ali approach and two linear approaches for headless modeling are also described. The sensitivity of model predictions to variations in parameter values is presented. A comparison with experimental results for ripening and steady state conditions shows that particle removal can be described well while the observed linear (with time) headless results cannot be described by modifications of the O'Melia and Ali approach. A surface area based linear headless model appears to capture the effects of suspended particle size on headless development while effects of coagulant type must be described by changes in model parameter values.
Heat stress is a notable occupational health hazard, particularly because global climate change intensified environmental heat exposure. Workers in high-temperature environments, such as landfill sites, encounter sign...
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In this article, the author’s name Habuer was incorrectly written as Mongolian Habuer. Incorrect version: Mongolian Habuer1 · Takeshi Fujiwara1 · Spoann Vin2 · Phat Chandara3 · Makoto Tsukiji1 Cor...
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