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Influence of hydraulic retention time in a two-phase upflow anaerobic sludge blanket reactor treating textile dyeing effluent using sago effluent as the co-substrate
2011
Senthilkumar, M. | Gnanapragasam, G. | Arutchelvan, V. | Nagarajan, S.
Purpose Textile dyeing and sago industries are the most polluting industries in South India, especially in industrial cities like Salem, Tamil Nadu, where textile dyeing and sago industries are clumped together geographically. Conventional physicochemical treatment followed by biological processes for the effluent generated from these industries are ineffective, costlier and produce huge quantities of hazardous sludge and harmful by-products which requires further treatment and safe disposal. Hence, the development of an alternative treatment method will become important. The main objective of this investigation is to establish a sustainable biotreatment technology for the treatment of textile dyeing effluent using sago effluent as co-substrate in a two-phase upflow anaerobic sludge blanket (UASB) reactor. Methods In this study, influence of hydraulic retention time (HRT) in a two-phase UASB reactor treating textile dyeing effluent using sago effluent as co-substrate was investigated with different HRTs (36, 30, 24 and 18 h) with an optimum mixing ratio of 70:30 (sago to textile dye wastewaters). Results The results revealed that the HRT had a high influence on the chemical oxygen demand (COD) and colour removal. The maximum COD removal efficiency of 39.4% and 88.5% and colour removal efficiency of 43.7% and 84.4% in the acidogenic and methanogenic reactors, respectively was achieved at 24 h of HRT. The biogas production was 312 L/day. Conclusion The biphasic UASB reactor could be a very feasible alternative, cost-effective, eco-friendly and sustainable treatment system for textile dyeing effluent with sago effluent as a co-substrate.
显示更多 [+] 显示较少 [-]Degradative fate of 3-chlorocarbazole and 3,6-dichlorocarbazole in soil
2011
Tröbs, Lisa | Henkelmann, Bernhard | Lenoir, Dieter | Reischl, Arthur | Schramm, Karl-Werner
Background, aim, and scope 3-Chlorocarbazole and 3,6-dichlorocarbazole were isolated from Bavarian soils. The stereospecific formation of the isomers of these chlorinated carbazols can be explained by quantum mechanical calculations using the DFT method. It was shown that chlorination of carbazole and 3-chlorocarbazole respectively is preferred via the sigma-complexes 3-chlorocarbazole and 3,6-dichlorocarbazole as the most stable products. The dioxin-like toxicological potential of 3,6-dichlorocarbazole, determined by the Micro-EROD Test, is in the range of some picogram TCDD equivalents per milligram carbazole. The degradative fate of 3-chlorocarbazole and 3,6-dichlorocarbazole was analysed within a long-term study (57 days) in soil. Materials and methods The soil was extracted by ASE (accelerated solvent extraction) and a further clean-up procedure with column chromatography and chromatography with C18-SPE stationary phases. Quantification of 3-chlorocarbazole and 3,6-dichlorocarbazole was performed employing the isotope-dilution method. The samples were measured with high-resolution GC/MS. Results The degradation (ln(c/c₀) vs. time with best-fit line) showed in almost every storage condition a very small degradation (slopes (h⁻¹) in −10⁻⁴ range). However, the decay for the controls were two to three times (−28°C) and six times (with sodium azide) higher, than the decrease of 3-chlorocarbazole and 3,6-dichlorocarbazole in the samples of environmental conditions. Discussion Especially because of the toxicological potential of 3-chlorocarbazole and 3,6-dichlorocarbazole the proven degradative fate is of large interest. The results show that the analysed carbazoles are not readily degradable in this time period. Conclusions The expected results of exponential decay behaviour could not be proven. Recommendation and perspectives Longer-lasting studies are expected to reveal more accurate half-lives, although it has been shown here, that the compounds are not readily degradable in their native soil environment.
显示更多 [+] 显示较少 [-]Polychlorinated biphenyls and organochlorinated pesticides in birds from a contaminated region in South China: association with trophic level, tissue distribution and risk assessment
2011
Zhang, Xiu-Lan | Luo, Xiao-Jun | Liu, Juan | Luo, Yong | Chen, She-Jun | Mai, Bi-Xian
Purpose Birds have been used successfully for biomonitoring of the levels and effects of persistent organic pollutants (POPs) in the environments; however, there is exceedingly little data on organochlorinated pesticide (OCPs) and polychlorinated biphenyls (PCBs) residues in bird inhabiting in China. In the present study, we detected the concentrations of PCBs, dichlorodiphenyltrichloroethane and its metabolites (DDTs) and hexachlorocyclohexanes (HCHs) in muscle, liver and kidney of birds that inhabit in an e-waste recycling site. Associated with the stable isotope ratio (δ ¹⁵N), we investigated the effect of trophic level on the body burdens of persistent contaminants in birds. The tissue distributions of contaminants in these birds were examined, and a preliminary risk assessment was also conducted. Materials and methods Specimens from eight bird species were collected from Qingyuan County, Guangdong Province, South China. Pectoral muscle, liver and kidney tissues were Soxhlet-extracted and finally dissolved in isooctane. Both PCBs and OCPs were analyzed by gas chromatography-mass spectrometry. The subsamples for nitrogen stable isotope analysis were lyophilized, ground and analyzed by a flash EA 112 series elemental analyzer interfaced with an isotope ration mass spectrometer. Results and discussion PCBs exhibited the highest concentrations among all target compounds, and a preliminary risk assessment suggested that adverse effects might occur in some birds for its high level. Generally, the concentrations of pollutants in liver and kidney were higher than those in muscle, which was mainly driven by passive diffusion to the ‘lipid-compartment'. Significant differences in level of contaminants were obtained among species due to the varieties in dietary composition and habitat. An increasing trend was obtained between concentrations of PCBs and DDTs with trophic levels; however, HCHs exhibited the same level among species. Recommendations and perspectives Because of the e-waste recycling activities, the study area has been heavily polluted by PCBs. Studies on the species-specific hazard assessment associated with exposure to PCBs are urgently needed in the study of birds in the area.
显示更多 [+] 显示较少 [-]Manganese in the urban atmosphere: identifying anomalous concentrations and sources
2011
Moreno, Teresa | Pandolfi, Marco | Querol, X (Xavier) | Lavín, Javier | Alastuey, A (Andrés) | Viana, Mar | Gibbons, Wes
Purpose Industrial emissions can raise urban background levels of inhalable Mn particles in an order of magnitude above normal, eclipsing the contribution made by natural sources and traffic. Methods The source of such emissions can be identified using a multidisciplinary approach which integrates ICP-MS chemical analyses of PM₁₀ and PM₂.₅ samples with positive matrix factorization source apportionment modelling, scanning electron microscopy and meteorological data. Results We apply this methodology to data from Santander (N Spain), where morning Mn-bearing industrial contamination sourcing from the SW is returned towards the city by afternoon NE sea breezes. This wind direction reversal carries the industrial pollution plume inland, detectably raising urban background levels of MnPM₁₀ in the town of Torrelavega 20 km away. Industrially sourced daily urban background Mn levels at Santander reach >1,000 ng/m³, average >150 ng/m³. Conclusions We demonstrate the anomalous nature of such concentrations by comparing them with >2,500 PM₁₀ chemical analyses of ambient PM₁₀ from other sites in Spain which show how current background Mn levels in urban air typically average only 10 ng/m³, rising to 20-25 ng/m³ in city traffic sites. Daily levels of atmospheric Mn PM₁₀ only rarely exceed 50 ng/m³, usually during desert dust intrusions which, in extreme cases (such as Canary Islands “calima” events from Africa) can produce Mn concentrations of 100-125 ng/m³.
显示更多 [+] 显示较少 [-]Organic matter compounds as source indicators and tracers for marine pollution in a western Mediterranean coastal zone
2011
Amorri, Jalila | Geffroy-Rodier, Claude | Boufahja, Fehmi | Mahmoudi, Ezzeddine | Aïssa, Patricia | Ksibi, Mohamed | Amblès, André
INTRODUCTION: Complex organic compounds found in oil and sediments linked with a particular source (such as algae, bacteria or vascular plants) are defined as biomarkers and are useful dating indicators in organic geochemistry. METHODS AND RESULTS: This paper presents the composition of the organic matter (OM) on marine surface sediments from a degraded Tunisian coast analysed by pyrolysis and gas chromatography–mass spectrometry (GC-MS). High total OM contents (0.3–4.2%) were detected with high levels of saturated linear hydrocarbons. The aliphatic lipids had contributed with up to 11.7% of the total OM, and their distribution had consisted of resolved compounds (n-alkanes and fatty acid (FAs)) and an unresolved complex mixture. Hydrocarbons, primarily n-alkanes, were ranged from 368 to 3,886 μg g−1. The FAs (674–2,568 μg g−1) were dominated by derived primary production, and the short chain FAs (C16 and C18) were the most abundant throughout. The ubiquitous presence of petroleum contamination, mainly from offshore oil exploration, discharge of pollutants from rivers, shipping activities and atmospheric deposition was found in all samples. The Gabès littoral seems to be quite to very polluted near the industrial zone of Ghannouch. The C/H ratio (generally around 5.9), the thermal analysis and GC-MS of n-alkanes and FAs showed that the OM in the studied area was composed of anthropogenic/petrogenic, marine and continental sources. CONCLUSIONS: Our study represents an innovative approach to assessing environmental pollution. The evaluation of organic matter by examination of sterols, alkanes and fatty acids allows the identification of source, both anthropogenic and natural.
显示更多 [+] 显示较少 [-]Interpreting methamphetamine levels in a high-use community
2011
Chiaia-Hernandez, Aurea C. | Banta-Green, Caleb J. | Field, Jennifer A.
INTRODUCTION: Illicit drug use is a largely hidden phenomenon, and population measures are notoriously problematic. Reliable and valid data for local, regional, and national public health and other interventions are needed. METHODS: To address this information, we examined temporal trends within and across weeks in methamphetamine (MA) in a single location in order to inform a sampling plan for understanding long-term trends in MA use based on sampling raw influent to wastewater treatment plants. The measured concentrations in the wastewater are used to estimate the total mass of MA consumed rather than the number of doses due to the uncertainty surrounding methamphetamine purity, mass of MA per dose, and the number of doses used per day. RESULTS: Results from a region with high levels of MA use indicate that MA levels do not differ significantly between weekdays and weekends (p = 0.1), consistent with a predominately regular, daily use pattern use. The potential contribution of legal sales of D: - and L: -MA to the mass of MA consumed within the community was estimated to range from 3–8%. Limitations and uncertainties associated with estimating the mass of MA consumption include small contributions of prescription and over-the-counter drugs that are metabolized to MA as well as measurement and sampling variability.
显示更多 [+] 显示较少 [-]Removal of alkylphenols from polluted sites using surfactant-assisted soil washing and photocatalysis
2011
Davezza, Manuela | Fabbri, Debora | Bianco Prevot, Alessandra | Pramauro, Edmondo
Background and purpose Surfactant-assisted soil washing and photocatalysis are well-known remediation processes of environmental concern. The application of photocatalysis to treat soil washing extracts containing 4-methylphenol, 4-ethylphenol and 4-tert-butylphenol in the presence of nonionic (C₁₂E₈ and C₁₂E₂₃) and anionic (SDS) surfactants and some of their binary mixtures was investigated in this work by studying the pollutants degradation in the presence of TiO₂ dispersions irradiated with simulated solar light. Materials and methods Clean soil samples were spiked with the investigated alkylphenols. Aqueous solutions of the chosen surfactants were placed in contact for some hours with the spiked soil samples in a rotatory mixer. The pollutants recoveries were evaluated via HPLC analysis. Photocatalytic experiments were performed in solarbox on aqueous solutions and on aqueous surfactant solutions containing the pollutants. Results The pollutants removal from the soil was proven effective using the examined surfactant solutions. The photocatalytic treatment of the wastes was faster using Brij 35, but also SDS and C₁₂E₈-SDS mixtures can be applied. After 2-5 h the complete pollutants abatement was obtained, depending on the surfactant chosen and on the amount of TiO₂ employed. On the contrary, the treatment of wastes containing C₁₂E₈ was an extremely slow process. Conclusions The photocatalytic approach can be applied to remove the examined aromatic pollutants from the washing wastes, confirming the viable coupling between this advanced oxidation method and the surfactant-based soil remediation treatments. Surfactant adsorption onto TiO₂ and micelles concentration play a dominant role.
显示更多 [+] 显示较少 [-]The performance of nature reserves in capturing the biological diversity on Hainan Island, China
2011
Wu, Ruidong | Ma, Guangzhi | Long, Yongcheng | Yu, Jiehua | Li, Shining | Jiang, Haisheng
Purpose The performance of nature reserves depends on the degree to which they represent a region's full biodiversity. Here, we conducted a study on Hainan Island, China, to assess how well Hainan's biodiversity features were captured by existing nature reserves. We also explored the driving forces behind the current protection pattern so as to provide guidelines for improving the island's conservation system. Methods We integrated the information on nature reserves, ecological variables, and human activities into a spatial database, then assessed the performance of nature reserves in representing natural variation, vegetation types, and species, and examined the impacts of human activities and land ownership on the current protection pattern. Results About 8.4% of Hainan Island was protected by nature reserves; the coverage was geographically biased toward its central mountainous areas with higher elevation, rugged terrain, and fertile soils. We found that 60% of the environmental units and 39.4% of the natural vegetation types had more than 10% of their area protected, respectively. Lowlands tended to have higher animal species richness, and the protection for endangered species was less efficient. Nature reserve coverage was negatively correlated with amount of converted habitats, human population density, and road density, and 82.4% of the total reserved area was allocated on state-owned land. Conclusions Nature reserve coverage was not enough to capture lowlands biodiversity features. The current protection pattern was significantly driven by several major conservation targets, human development, planning methods, and land ownership. To improve its conservation system, Hainan should enhance protection in the north and northeast plains and coastal regions, implement systematic planning approaches to define clear visions for guiding future conservation actions, and develop flexible management and funding mechanisms toward sustainable use of natural resources.
显示更多 [+] 显示较少 [-]Statistical analysis and isotherm study of uranium biosorption by Padina sp. algae biomass
2011
Khani, Mohammad Hassan
Introduction The application of response surface methodology is presented for optimizing the removal of U ions from aqueous solutions using Padina sp., a brown marine algal biomass. Methods Box-Wilson central composite design was employed to assess individual and interactive effects of the four main parameters (pH and initial uranium concentration in solutions, contact time and temperature) on uranium uptake. Results and discussion Response surface analysis showed that the data were adequately fitted to second-order polynomial model. Analysis of variance showed a high coefficient of determination value (R ² = 0.9746) and satisfactory second-order regression model was derived. Conclusion The optimum pH and initial uranium concentration in solutions, contact time and temperature were found to be 4.07, 778.48 mg/l, 74.31 min, and 37.47°C, respectively. Maximized uranium uptake was predicted and experimentally validated. The equilibrium data for biosorption of U onto the Padina sp. were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 376.73 mg/g.
显示更多 [+] 显示较少 [-]Uranium biosorption by Padina sp. algae biomass: kinetics and thermodynamics
2011
Khani, Mohammad Hassan
INTRODUCTION: Kinetic, thermodynamic, and equilibrium isotherms of the biosorption of uranium ions onto Padina sp., a brown algae biomass, in a batch system have been studied. DISCUSSION: The kinetic data were found to follow the pseudo-second-order model. Intraparticle diffusion is not the sole rate-controlling factor. The equilibrium experimental results were analyzed in terms of Langmuir isotherm depending with temperature. Equilibrium data fitted very well to the Langmuir model. The maximum uptakes estimated by using the Langmuir model were 434.8, 416.7, 400.0, and 370.4 mg/g at 10°C, 20°C, 30°C, and 40°C, respectively. Gibbs free energy was spontaneous for all interactions, and the adsorption process exhibited exothermic enthalpy values. Padina sp. algae were shown to be a favorable biosorbent for uranium removal from aqueous solutions.
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