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Resultados 1721-1730 de 4,042
Removal Performance, Antibacterial Effects, and Toxicity Assessment of Ciprofloxacin Treated by the Electrocoagulation Process Texto completo
2016
Espinoza-Quiñones, FernandoR. | de Souza, AriádineR. C. | Módenes, AparecidoN. | Trigueros, DanielaE. G. | de Pauli, AlineR. | de Souza, PatríciaS. C. | Kroumov, AlexanderD.
This study is concerned with the removal performance of the antibiotic ciprofloxacin (CIP) from synthetic solutions by electrocoagulation (EC), as well as the toxic effects of treated CIP solutions. A response surface analysis (RSA) was applied to search optimal operational parameter values of the pH of solution, electrical current density (ECD), and electrolysis time (ET). The EC efficiency was evaluated by determining the total organic carbon (TOC) and CIP concentration performed by high-performance liquid chromatography. Although the best EC efficiency was attained at pH = 8, ECD = 22.2 A m⁻², and ET = 75 min, toxicity and antibacterial tests were performed using Artemia salina cysts and Staphylococcus aureus and Escherichia coli microorganisms in a wide ET range and other pH and ECD values. Increasing optimal pH value (9), along with reducing optimal ECD value (18 A m⁻²) and regarding low ET values, similar results for the removal of CIP (98%) and TOC (87%) were also attained. Toxicity variation was observed during EC process in synthetic solutions with the lowest antibacterial effects due to CIP and recalcitrant compound residues after 40 min of ET. These results clearly showed that the EC process presents a promising alternative method for the treatment of wastewaters containing high CIP concentrations.
Mostrar más [+] Menos [-]Distribution and origins of n-alkanes, hopanes, and steranes in rivers and marine sediments from Southwest Caspian coast, Iran: implications for identifying petroleum hydrocarbon inputs Texto completo
2016
Shirneshan, Golshan | Bakhtiari, Alireza Riyahi | Memariani, Mahmoud
The occurrence of n-alkanes and biomarkers (hopane and sterane) in surface sediments from Southwestern coasts of Caspian Sea and 28 rivers arriving to this lake, determined with a gas chromatography–mass spectrometry method, was used to assess the impacts of anthropogenic activities in the studied area. The concentrations of total n-alkanes (Σ21 n-alkane) in costal and riverine sediments varied from 249.2 to 3899.5 and 56 to 1622.4 μg g⁻¹, respectively. An evaluation of the source diagnostic indices indicated that petroleum related sources (petrogenic) were mainly contributed to n-alkanes in costal and most riverine sediments. Only the hydrocarbons in sediment of 3 rivers were found to be mainly of biogenic origin. Principal component analysis using hopane diagnostic ratios in costal and riverine sediments, and Anzali, Turkmenistan, and Azerbaijan oils were used to identify the sources of hydrocarbons in sediments. It was indicated that the anthropogenic contributions in most of the costal sediment samples are dominated with inputs of oil spills from Turkmenistan and Azerbaijan countries.
Mostrar más [+] Menos [-]Metal contamination status of the soil-plant system and effects on the soil microbial community near a rare metal recycling smelter Texto completo
2016
Li, Zhu | Ma, Tingting | Yuan, Zheng | Hou, Jinyu | Wang, Qingling | Wu, Longhua | Christie, Peter | Luo, Yongming
Four heavy metals (Cd, Cu, Pb and Zn), two metalloids (As and Sb) and two rare metals (In and Tl) were selected as target elements to ascertain their concentrations and accumulation in the soil-plant system and their effects on the structure of the soil microbial community in a typical area of rare metal smelting in south China. Twenty-seven soil samples 100, 500, 1000, 1500 and 3000 m from the smelter and 42 vegetable samples were collected to determine the concentrations of the target elements. Changes in soil micro-organisms were investigated using the Biolog test and 454 pyrosequencing. The concentrations of the eight target elements (especially As and Cd) were especially high in the topsoil 100 m from the smelter and decreased markedly with increasing distance from the smelter and with increasing soil depth. Cadmium bio-concentration factors in the vegetables were the highest followed by Tl, Cu, Zn, In, Sb, Pb, and then As. The concentrations of As, Cd and Pb in vegetables were 86.7, 100 and 80.0 %, respectively, over the permissible limits and possible contamination by Tl may also be of concern. Changes in soil microbial counts and average well colour development were also significantly different at different sampling distances from the smelter. The degree of tolerance to heavy metals appears to be fungi > bacteria > actinomycetes. The 454 pyrosequencing indicates that long-term metal contamination from the smelting activities has resulted in shifts in the composition of the soil bacterial community.
Mostrar más [+] Menos [-]Synergy Between Diazinon and Nonylphenol in Toxicity During the Early Development of the Rhinella arenarum Toad Texto completo
2016
Aronzon, Carolina Mariel | Svartz, Gabriela Verónica | Coll, Cristina Silvia Pérez
Diazinon is an extensively applied organophosphate pesticide, and nonylphenol is one of the major degradation products of nonylphenol polyethoxylates which are commonly used as surfactant in pesticide formulations. Both pollutants are widely distributed and often coexist in agroecosystems, where they might cause toxic effects to wild biota. This study assessed single and joint toxicity of binary mixtures of these organic compounds on the early development of Rhinella arenarum by means of a standardized test. Joint toxicity of diazinon/nonylphenol mixtures were assessed in embryos and larvae exposed to three different proportions at different exposure times. Embryo and larval toxicity was time-dependent, and larvae were significantly more sensitive than embryos to both compounds. For both embryos and larvae, nonylphenol was between 11 and 18 times more toxic than diazinon. Joint toxicity of the chemicals showed a tendency to be significantly higher than the predicted by additivity effects highlighting the threat that diazinon/nonylphenol mixtures represent for Rhinella arenarum populations.
Mostrar más [+] Menos [-]Photocatalytic Degradation of Acid Orange II Using Activated Carbon Fiber-Supported Cobalt Phthalocyanine Coupled with Hydrogen Peroxide Texto completo
2016
Wang, Tiecheng | Li, Yujuan | Qu, Guangzhou | Liang, Dongli | Hu, Shibin
Activated carbon fiber-supported cobalt phthalocyanine photocatalyst (Co-TDTAPc-F) was prepared in this study, and its performance for dye wastewater decoloration was investigated, and Acid Orange II (AO7) was selected as the target pollutant. The morphology analysis of Co-TDTAPc-F was conducted, and the effects of catalyst loading, H₂O₂ addition, solution pH, and catalyst reuse on AO7 decoloration efficiency were evaluated. The results showed that AO7 decoloration efficiency increased by 23.2% during the Co-TDTAPc-F photocatalytic process as compared with solely Co-TDTAPc-F adsorption, and the decoloration process was fitted by pseudo first-order reaction. The increase of catalyst loading and H₂O₂ content both benefitted AO7 decoloration. Strong photocatalytic activities were observed at both acidic and alkaline conditions; however, total organic carbon (TOC) removal efficiency decreased with the increase of solution pH. Strong photocatalytic activity was still observed after four times reuse. The mechanisms of AO7 photocatalytic decomposition by Co-TDTAPc-F were proposed.
Mostrar más [+] Menos [-]Toxicities of 48 pharmaceuticals and their freshwater and marine environmental assessment in northwestern France Texto completo
2016
Minguez, Laetitia | Pedelucq, Julie | Farcy, Emilie | Ballandonne, Céline | Budzinski, Hélène | Halm-Lemeille, Marie-Pierre
A risk assessment for freshwater and marine ecosystems is presented for 48 pharmaceutical compounds, belonging to 16 therapeutic classes, and prescribed in northwestern France. Ecotoxicity data were obtained on two freshwater organisms, i.e., crustacean Daphnia magna and the green algae Pseudokirchneriella subcapitata, and on two marine organisms, i.e., the crustacean Artemia salina and the diatom Skeletonema marinoi. Measured environmental concentrations (MEC), in the Orne River and sea off Merville-Franceville in the Basse-Normandie region, were compared to the predicted environmental concentrations (PEC). Predicted no-effect concentrations (PNEC) were derived from acute data for each compound. Then, a risk assessment for each compound and the mixture was performed by calculating risk quotients (RQ as PEC or MEC/PNEC ratio). Results showed that no immediate acute toxicities were expected even if some compounds displayed strong toxicities at very low concentrations. Antibiotics, antidepressants, and antifungals would deserve attention because of their high or median ecological risk suspected on marine and freshwater ecosystems. Marine ecosystems would be more sensitive to pharmaceutical residues.
Mostrar más [+] Menos [-]Simulation of the Contribution of Phosphorus-Containing Minerogenic Particles to Particulate Phosphorus Concentration in Cayuga Lake, New York Texto completo
2016
Gelda, Rakesh K. | Effler, Steven W. | Prestigiacomo, Anthony R. | Peng, Feng | Auer, Martin T. | Kuczynski, Anika | Chapra, Steven C.
Phosphorus (P) associated with minerogenic particles delivered from watersheds can interfere with the common use of total P (TP) concentration as a trophic state metric in lacustrine systems, particularly proximate to tributary entries, because of its limited bioavailability. The concentration of unavailable minerogenic particulate P (PPₘ/ᵤ), where it is noteworthy, should be subtracted from TP in considering primary production potential and trophic state levels. A first mass balance model for PPₘ/ᵤ is developed and tested here for Cayuga Lake, New York. This is supported by a rare combination of detailed information for minerogenic particle level dynamics for the tributaries and lake, the bioavailability of tributary particulate P (PP), and previously tested hydrothermal/transport and minerogenic particle concentration submodels. The central roles of major runoff events and localized tributary loading at one end of the lake in driving patterns of PPₘ/ᵤ in time and space are well simulated, including (1) the higher PPₘ/ᵤ concentrations in a shallow area (“shelf”) adjoining the inputs, relative to pelagic waters, following runoff events, and (2) the positive dependence of the shelf increases on the magnitude of the event. The PPₘ/ᵤ component of P was largely responsible for the higher summer average TP on the shelf vs. pelagic waters and the exceedance of a TP water quality limit on the shelf. The effective simulation of PPₘ/ᵤ allows an appropriate adjustment of TP values to avoid overrepresentation of potential primary production levels.
Mostrar más [+] Menos [-]Polyhydroxyalkanoate Biosynthesis from Paper Mill Wastewater Treated by a Moving Bed Biofilm Reactor Texto completo
2016
Baeza, Rocío | Jarpa, Mayra | Vidal, Gladys
One potential way for organic matter recovering contained in paper mill effluents can be obtaining polyhydroxyalkanoate (PHA). The aim of this work was to evaluate PHA biosynthesis from paper mill effluents by moving bed biofilm reactor (MBBR) under different operational strategies of the BOD₅/nitrogen (N)/phosphorus (P) ratio. The operational strategies were evaluated in two phases. During phase I, organic loading rates (OLRs) were increased from 0.13 to 2.99 biological oxygen demand kg BOD₅ m⁻³ day⁻¹, and in phase II, kg BOD₅ m⁻³ day⁻¹ was increased from 0.81 to 2.83. In both phases, the BOD₅/N/P ratios were 100:5:1 and 100:1:0.3. The maximum percentages of PHA-accumulating cells and organic matter removal were 85.10 and 95.60 % for phase I, both with a BOD₅/N/P ratio of 100:5:1, while in phase II, PHA biosynthesis and organic removal were 89.41 and 97.10 % with 100:1:0.3 and 100:5:1, respectively.
Mostrar más [+] Menos [-]Multidisciplinary Approaches to Handling Wastes in Sugar Industries Texto completo
2016
Bhatnagar, Amit | Kesari, Kavindra Kumar | Shurpali, Narasinha
The global sugarcane production is about 1.91 billion tons annually and is concentrated in tropical regions, particularly in developing nations in Latin America and Asia. According to the UN Food and Agricultural Organization (FAO), there are over 100 countries producing sugarcane today. The increase in sugarcane production implies a proportional increase in sugar industry wastes. As a consequence of such increasing trend, sugar industries are facing severe environmental problems due to the lack of sustainable solutions for their waste management. Therefore, immediate attention is required to find a proper way of management to deal with sugar industry wastes and effluent in order to minimize environmental pollution and associated health risks. In this paper, different sources of solid and liquid wastes from sugarcane agriculture and associated sugar agro-industries are reviewed and valorization approaches of these different wastes are discussed. Some of the important resource recovery options from sugar industry wastes, which have been discussed in this review, include ethanol production, recovery of chemicals, use of bagasse and bagasse fly ash as adsorbents in water treatment and building materials. Technologies associated with the treatment of wastewater from sugar industries and efficient ways of utilization of this treated water in agriculture with special attention to measurement of crop water use efficiency are reviewed in view of our own research activities carried out in the past.
Mostrar más [+] Menos [-]Influence of Abiotic Factors on the Spatio-temporal Distribution of Rotifers in a Subtropical Lake of Western Himalaya Texto completo
2016
Inaotombi, S. | Gupta, P. K. | Mahanta, P. C.
Spatial and temporal variation of rotifers in Lake Sattal of Western Himalaya was studied from January 2011 to December 2012. A total of 22 rotifer species could be identified in the lake with a biannual mean abundance of 2.07 × 10⁶ individuals/m³ in eastern basin and 1.92 × 10⁶ individuals/m³ in western basin having maximum abundance during summer season. The main factors regulating distribution patterns of rotifers are nutrients, viz. NH₄-N, PO₄-P, NO₂-N, and NO₃-N, and turbidity, pH, and transparency. Six species of rotifers were deliberated as important species based on importance value index. Keratella quadrata, Colurella obtusa, and Asplanchna priodonta flourish under low turbid conditions. Philodina roseola demonstrated as a phosphorous-tolerant species, whereas K. quadrata and C. obtusa are thermophilous and their distributions are highly influenced by pH and transparency. The total organic matter (TOM) of the sediment has a significant positive correlation with species richness and diversity. The hierarchical environmental descriptor suggests water chemistry has a greater significant role in assemblages of rotifers as compared to sediment characteristics.
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