Characterization of a simple bacterial consortium for effective treatment of wastewaters with reactive dyes and Cr(VI)

A microbial consortia consisting of three bacteria isolated from tanning and textile wastewaters revealed high capacity to simultaneously bioaccumulate dye and Cr(VI). The identity of the bacteria were determined by 16S rRNA gene analysis to be closely related to Ochrobactrium sp., Salmonella enterica and Pseudomonas aeruginosa. Dependence of initial pH values and range of concentrations of the dye Reactive Black B (33.2-103.1 mg l(-1)) and Cr(VI) (19.9-127.6 mg l(-1)) were examined to find the effect of pH on the dye and Cr(VI) bioaccumulation. Optimal pH for growth of the consortia in media containing 35 mg l(-1) dye and 50 mg l(-1) Cr(VI) was determined to be around 8. The Cr(VI) bioaccumulation by the consortia was rapid in media containing molasses with or without reactive dye with a maximum Cr(VI) bioaccumulation yield ranging from 90% to 99% within a 2-4d period. A slightly lower yield for the dye bioaccumulation was measured with a maximum dye bioaccumulation of 80% at 59.3 mg l(-1) dye and 69.8 mg l(-1) Cr(VI). The highest specific Cr uptake value was obtained as 76.7 mg g(-1) at 117.1 mg l(-1) Cr(VI) and 50.8 mg l(-1) dye concentration. This ability to bioaccumulate dye and Cr(VI) was more efficient than the enriched sludge from which they were isolated.     

A model for prediction of product distributions for the reactions of phenol derivatives with hydroxyl radicals

In this study, with the intention of estimating the photocatalytic or photodegradation rates and finding certain predictors to be used for the determination of the most probable reaction path and the primary intermediate, the reactions of (*)OH radicals with 11 phenol derivatives including benzene were modeled. For 43 possible reaction routes, calculations of the geometric parameters, the electronic and thermodynamic properties of the reactants, the product radicals and the transition state complexes were performed with the semiempirical PM3 and DFT/B3LYP/6-31G(*) methods. The solvation effects were computed using COSMO as the solvation model. Based on the results of quantum mechanical calculations, the rate constants, the branching ratios and the product distributions of all the possible reaction paths were calculated by means of the transition state theory. Three predictors were determined for the prediction of the most probable transition state and the reaction path. The differences in the reaction rates were explained in terms of the presence of hydrogen bonds in the transition state complexes and the entropy effects. Finally the results obtained were compared with the available experimental data in order to assess the reliability of the proposed model.     

An 'artificial mussel' for monitoring heavy metals in marine environments

A new chemical sampling device, artificial mussel (AM), has been developed for monitoring metals in marine environments. This device consists of a polymer ligand suspended in artificial seawater within a Perspex tubing, and enclosed with semi-permeable gel at both ends. Laboratory and field experiments were carried out to examine the uptake of five metals (Cd, Cr, Cu, Pb and Zn) by the AM. Uptake of metals by AM was proportional to the exposure metal concentrations, and the AM was able to accumulate the ASV labile fractions of metals. Uptake and release of the metals of AM are similar to those of the mussel Perna viridis, but less affected by salinity and temperature. Field studies demonstrated that the AM can not only provide a time-integrated estimate of metals concentrations, but also allows comparisons of metal levels in different environments and geographical areas beyond the natural distribution limits of biomonitors.     

Optimal planning of co-firing alternative fuels with coal in a power plant by grey nonlinear mixed integer programming model

Energy supply and use is of fundamental importance to society. Although the interactions between energy and environment were originally local in character, they have now widened to cover regional and global issues, such as acid rain and the greenhouse effect. It is for this reason that there is a need for covering the direct and indirect economic and environmental impacts of energy acquisition, transport, production and use. In this paper, particular attention is directed to ways of resolving conflict between economic and environmental goals by encouraging a power plant to consider co-firing biomass and refuse-derived fuel (RDF) with coal simultaneously. It aims at reducing the emission level of sulfur dioxide (SO(2)) in an uncertain environment, using the power plant in Michigan City, Indiana as an example. To assess the uncertainty by a comparative way both deterministic and grey nonlinear mixed integer programming (MIP) models were developed to minimize the net operating cost with respect to possible fuel combinations. It aims at generating the optimal portfolio of alternative fuels while maintaining the same electricity generation simultaneously. To ease the solution procedure stepwise relaxation algorithm was developed for solving the grey nonlinear MIP model. Breakeven alternative fuel value can be identified in the post-optimization stage for decision-making. Research findings show that the inclusion of RDF does not exhibit comparative advantage in terms of the net cost, albeit relatively lower air pollution impact. Yet it can be sustained by a charge system, subsidy program, or emission credit as the price of coal increases over time.     

Photocatalytic decomposition of N<Subscript>2</Subscript>O over g-C<Subscript>3</Subscript>N<Subscript>4</Subscript>/WO<Subscript>3</Subscript> photocatalysts

Although the nitrous oxide belongs among three of the most contributing greenhouse gases to global warming, it is quite neglected by photocatalytic society. The g-C₃N₄ and WO₃ composites were therefore tested for the photocatalytic decomposition of N₂O for the first time. The pure photocatalysts were prepared by simple calcination of precursors, and the composites were prepared by mixing of suspension of pure components in water followed by calcination. The structural (X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy), textural (N₂ physisorption), and optical properties (diffuse reflectance spectroscopy, photoluminescence spectroscopy, photoelectrochemical measurements) of all composites were correlated with photocatalytic activity. The experimental results and results from characterization techniques confirmed creation of Z-scheme in the WO₃/g-C₃N₄ composites, which was confirmed by hydroxyl radicals’ trapping measurements. The photocatalytic decomposition of N₂O was carried out in the presence of UVA light (peak intensity at 365 nm) and the 1:2 WO₃/g-C₃N₄ composite was the most active one, but the photocatalytic activity was just negligibly higher than that of pure WO₃. This is caused by relatively weak interaction between WO₃ and g-C₃N₄ which was revealed from XPS.     

Concentrations of polycyclic aromatic hydrocarbon in the surface sediments from inter-tidal areas of Kenting coast,Taiwan

The main objective of this study was to investigate the concentrations of polycyclic aromatic hydrocarbons (PAHs) in inter-tidal sediments of the Kenting coast, Taiwan, to assess the levels and origin of PAHs, and to provide useful information on the potential ecological risk of PAHs to benthic organisms. The total concentrations of 38 PAHs ranged from 0.2 to 493 ng/g dry weight. The high variation in total PAH concentrations was caused by the sand content of the sediment in the area. Compared with other coasts and bays in the world, the concentrations of PAHs in the inter-tidal surface sediment of the Kenting coast is low to moderate. Based on the sediment quality guidelines, the total PAH concentrations were below the effects range low value, indicating that the PAH levels in the Kenting area were within minimal effects ranges for benthic organisms. Principal component analysis and isomer ratios were analyzed to identify the contamination source in the inter-tidal surface sediment of the Kenting coast. The results of compounds’ pattern and origin analysis suggest that the source of PAHs in the inter-tidal surface sediment of the Kenting coast is the combustion of petroleum and biomass.     

Toxicity of wood leachate to algae Desmodesmus subspicatus and plant Lemna minor

Environmental Science and Pollution Research - Wood is one of the extensively used goods on the earth due to its large accessibility and usage in a wide range of human life. When woods are exposed...     

Feasibility study on high-temperature sorption of hydrogen sulfide by natural soils

In this study, seven natural soils were tested for the sorption of hydrogen sulfide from coal gasification gas at high temperature. Results indicate that the LP natural soil has the best performance and the highest sulfur sorption capacity. After extracting free iron oxides, most natural soils have no sorption efficiency. The free iron oxides, therefore, proved to be the major components that react with hydrogen sulfide to form iron sulfides. The sulfur sorption capacity, either determined by EA or breakthrough time, is very close to the theoretical value based on the stoichiometric calculation with the content of free iron oxides. Moreover, the presence of CO is a positive effect while H2 is a negative effect. This can be explained via the water-shift reaction. On the basis of the results of temperature-programmed sulfidation (TPS), the starting temperature for the sorption of hydrogen sulfide is between 623-673 K. From the analyses of temperature-programmed oxidation (TPO) and XPS, the iron polysulfides are the major products and approximately 90% regeneration efficiency can be theoretically achieved while the temperature is controlled higher than 813 K. In the regeneration tests, the results show that the LP natural soil can be regenerated and thus reused after the oxidation process. No significant degeneration occurs on the LP natural soil after five sorption/regeneration cycles. The sulfur sorption capacity of the tenth regenerated soil can be achieved at least 80% compared to the fresh one. The experimental analyzed SO2 concentration from the regeneration process is almost identical to the theoretical calculated equilibrium concentration of the process. Maghemite is the main product after the regeneration process.     

Survey of urinary nickel in residents of areas with a high density of electroplating factories

The soil metal contamination arising from the discharge of the high density of electroplating factories in the geographic center of Taiwan has prompted concern about human exposure to harmful metals. This study aimed to determine the levels of nickel (Ni) in urine of residents living in the high vs. low factory-density areas, and to examine how these levels relate to gender and age. A total of 660 subjects, resident in the area for the last five years, were sampled according to the stratified random sampling approach, at ages 35-44, 45-54, and 55-64years for both genders. Metals in urine samples were analyzed by inductively coupled plasma mass spectrometry (ICPMS). The geometric mean (95% confidence interval (CI)) of urinary Ni was 6.30 (5.99-6.62)mug/l. The 0.95 parametric reference interval (90% CI) of urinary Ni was estimated to be 1.74 (1.62-1.88) to 22.73 (21.14-24.44)mug/l. Subjects in the areas with a high density of electroplating factories had significantly higher urinary Ni levels than those in the low-density areas, but both types of areas had obviously higher urinary Ni levels when compared to the non-occupationally exposed population from western countries. The health significance of elevated urinary Ni and its causative factors remain to be determined.     

Health risk of aerosols and toxic metals from incense and joss paper burning

We report for the first time the distribution and hazard potential of aerosol and metals resulting from joss paper burning. Burning joss paper and incense is a traditional custom in many Oriental countries. Large amounts of air pollutants, including particles, polycyclic aromatic hydrocarbons, toxic metals and other gaseous pollutants, are released into the environment during the burning stage. Many investigations have reported on the emission of pollutants from the incense burning. However, no work has been reported until now on the analysis of the released pollutants apart from polycyclic aromatic hydrocarbons. In this study, a micro-orifice uniform-deposit impactor and inductively coupled plasma optical emission spectrometry were, respectively, used to collect aerosols and characterize the toxic metals from joss paper burning. We studied two types of particulate matter (PM): PM_2.5 that are particles with a diameter smaller than 2.5 μm and PM₁₀ that are particles with a diameter smaller than 10 μm. PM_2.5 are the most potentially toxic particles. Our results showed that PM_2.5 are the major component of the pollutants and that the PM_2.5 to PM₁₀ ratio ranged from 62 to 99%. The metals Na, Ca, Mg, Al and K were the main species in the aerosol and in the bottom ash.