60 research outputs found
Pollutant removals of an urban riparian artificial wetland and its reconstruction in Taipei Basin after Typhoon Aere.
No full textAn innovative modeling approach using Qual2K and HEC-RAS integration to assess the impact of tidal effect on river water quality simulation
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Comparative study of multimedia models applied to the risk assessment of soil and groundwater contamination sites in Taiwan
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Treatment of Septic Tank Effluents by a Full Scale Capillary Seepage Soil Biofiltration System.
No full textUrban Pollutant Removal by a Constructed Riparian Wetland before Typhoon Damage and after Reconstruction.
No full textComparative Study of Multimedia Models Applied to the Risk Assessment of Soil and Groundwater Contamination Sites in Taiwan
No full textSolubilities of PAHs in alcohol-water mixtures
No full textSolubilities of phenanthrene, pyrene, and perylene were determined in aqueous solutions containing either methanol, ethanol, or propanol at alcohol volume fractions ranging from zero to nearly one, at 25\sp\circC under atmospheric pressure. These data, and data from the literature on naphthalene, were compared to 2, 3, and 4 interaction-parameter Margules equations and UNIFAC predictions. For each solute-solvent-cosolvent (i.e., PAH-water-alcohol) system examined, the solubility of each PAH increased with increasing alcohol volume fraction. The UNIFAC model poorly estimated solubilities at cosolvent volume fractions near 0.5. Analysis of the data with various forms of the Margules equations suggests that, in addition to solute-solvent and solute-cosolvent interactions, solvent-cosolvent (i.e., water-alcohol) and solute-solvent-cosolvent interactions are important at cosolvent volume fractions near 0.5. A simplified three-suffix Margules model is proposed, which includes terms for all these interactions and accurately estimates the experimental data with a consistent set of interaction parameters. All interaction parameters involving solute molecules may be estimated from the octanol-water partition coefficient, K\sb{ow}, of the respective solute. This empirical result suggests that the solubility of other PAHs in similar alcohol-water mixtures may be estimated from K\sb{ow}, and enthalpy of fusion. Additionally, extension of Margules equations to quaternery systems were conducted and evaluated. Generally, the two-suffix model is able to calculate the PAHs solubilities in ternary solvent systems studied. The deviation of calculated PAH\u27s solubilities from experimental measurements for systems containing phenol as cosolvent results from the complex molecular interactions of phenol. Similar solubility data for phenanthrene and pyrene were determined at 4\sp\circ and 43\sp\circC. Combined the data at 25\sp\circC, these data were analyzed with van\u27t Hoff\u27s equation. At each temperature, solubility increases as alcohol volume fraction concentration increases. The data suggests that excess enthalpies of the solute are close to zero. Assuming excess enthalpies as zero, excess entropy was calculated to be nearly independent of temperature
Degradation of Methyl Paraben by the Aerated Pebble-bed Biofilm System
No full textAbstractMethyl parben is an often-used anti-septic chemical in personal care products, and its discharge along with domestic sewage or municipal wastewater resulted in the elevated concentration in natural water bodies. To mitigate its impact to the aquatic environment, this study aimed to investigate the methyl paraban degradation by an aerated pebble-bed biofilm system at various hydraulic retention times. The influent methyl paraben concentration was 10mg/L. The degradation of methyl paraben and synthetic municipal wastewater mixture was evaluated at their respective concentrations of 10mg/L and 50mg COD/L. The results indicated that the removal efficiency of BOD at 1 hour hydraulic retention time was 83.7%, and this efficiency increased to 92.54% as the hydraulic retention time increased to 3hours. The BOD removal efficiencies for methyl paraben and municipal wastewater mixture were higher than those for wastewaters containing only methyl paraben. The influent initial pH was around 4.7 because of hydrolysis of methyl paraben, during which hydrogen ions were released. The pH exhibited an increasing trend as the wastewater travelled through the system. For methyl paraben removal, the efficiencies for wastewater containing only methyl paraben were higher than those for methyl paraben and municipal wastewater mixture. An apparent competition between methyl paraben and municipal wastewater was observed. The methyl paraben degradation followed the 1st order kinetics
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