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Resultados 3191-3200 de 4,308
Integrated management of ash from industrial and domestic combustion: a new sustainable approach for reducing greenhouse gas emissions from energy conversion Texto completo
2017
Benassi, Laura | Dalipi, Rogerta | Consigli, Veronica | Pasquali, Michela | Borgese, Laura | Depero, Laura E. | Clegg, Francis | Bingham, Paul A. | Bontempi, Elza
This work supports, for the first time, the integrated management of waste materials arising from industrial processes (fly ash from municipal solid waste incineration and coal fly ash), agriculture (rice husk ash), and domestic activities (ash from wood biomass burning in domestic stoves). The main novelty of the paper is the reuse of wood pellet ash, an underestimated environmental problem, by the application of a new technology (COSMOS-RICE) that already involves the reuse of fly ashes from industrial and agricultural origins. The reaction mechanism involves carbonation: this occurs at room temperature and promotes permanent carbon dioxide sequestration. The obtained samples were characterized using XRD and TGA (coupled with mass spectroscopy). This allowed quantification of the mass loss attributed to different calcium carbonate phases. In particular, samples stabilized using wood pellet ash show a weight loss, attributed to the decomposition of carbonates greater than 20%. In view of these results, it is possible to conclude that there are several environmental benefits from wood pellet ash reuse in this way. In particular, using this technology, it is shown that for wood pellet biomass the carbon dioxide conversion can be considered negative.
Mostrar más [+] Menos [-]Effects of Cd and Zn on physiological and anatomical properties of hydroponically grown Brassica napus plants Texto completo
2017
Benáková, Martina | Ahmadi, Hassan | Dučaiová, Zuzana | Tylová, Edita | Clemens, Stephan | Tůma, Jiří
Clarifying the connection between metal exposure and anatomical changes represents an important challenge for a better understanding of plant phytoextraction potential. A hydroponic screening experiment was carried out to evaluate the effects of combined interactions of Cd and Zn on mineral uptake (Mg, K, Ca, Na) and on the physiological and anatomical characteristics of Brassica napus L cv. Cadeli, Viking, and Navajo. Plants were exposed to 5 μM Cd (CdCl₂), 10 μM Zn (ZnSO₄), or both Cd + Zn, for 14 days. Cadmium exposure led to a significant reduction in root growth, shoot biomass, and chlorophyll content. After Cd-only and Cd + Zn treatment, primary root tips became thicker and pericycle cells were enlarged compared to the control and Zn-only treatment. No differences between metals were observed under UV excitation, where all treatments showed more intensive autofluorescence connected with lignin/suberin accumulation compared to control conditions. The highest concentrations of Cd and Zn were found in the roots of all tested plants, and translocation factors did not exceed the threshold of 1.0. The root mineral composition was not affected by any treatment. In the shoots, the Mg concentration slightly increased after Cd-only and Cd + Zn treatments, whereas Zn-only treatment caused a sharp decrease in Ca content. Slight increases in K were seen after the addition of Zn. Significantly higher concentrations of Na were induced by Cd- or Zn-only treatment.
Mostrar más [+] Menos [-]Titanium dioxide-based sonophotocatalytic mineralization of bisphenol A and its intermediates Texto completo
2017
Sunasee, Sharmini | Wong, Kien Tiek | Lee, Gooyong | Pichiah, Saravanan | Ibrahim, Shaliza | Park, Chulhwan | Kim, Nam Chan | Yoon, Yeomin | Jang, Min
In this study, bisphenol A (BPA) removal by sonophotocatalysis coupled with commercially available titanium dioxide (TiO₂, P25) was assessed in batch tests using energy-based advanced oxidation combining ultrasound (US) and ultraviolet (UV). The kinetics of BPA removal were systematically evaluated by changing operational parameters, such as US frequency and power, mechanical stirring speed, and temperature, but also comparison of single and coupled systems under the optimum US conditions (35 kHz, 50 W, 300 rpm stirring speed, and 20 °C). The combination of US/UV/P25 exhibited the highest BPA removal rate (28.0 × 10⁻³ min⁻¹). In terms of the synergy index, the synergistic effect of sonophotocatalysis was found to be 2.2. This indicated that sonophotocatalysis has a considerably higher removal efficiency than sonocatalysis or photocatalysis. The removal of BPA was further investigated to identify BPA byproducts and intermediates using high-performance liquid chromatography–mass spectrometry. Five main intermediates were formed during sonophotocatalytic degradation, and complete removal of BPA and its intermediates was obtained after 3 h of operation. The degradation pathway of BPA by sonophotocatalysis was also elucidated.
Mostrar más [+] Menos [-]Heavy metals bioconcentration from soil to vegetables and appraisal of health risk in Koka and Wonji farms, Ethiopia Texto completo
2017
Eliku, Temesgen | Leta, Seyoum
Heavy metal accumulation in agricultural crops has grown a major concern globally as a result of a significant health impact on human. The quantification of heavy metals (Cd, Pb, Cr, Zn, Cu, and Ni) in the soil and vegetables at two sites (Koka and Wonji Gefersa) was done using flame atomic absorption spectrophotometer. The mean concentrations of heavy metals in vegetable fields’ soil samples obtained from Koka were higher for Pb, Cr, Zn, Cu, and Ni. The overall results of soil samples ranged 0.52–0.93, 13.6–27.3, 10.0–21.8, 44.4–88.5, 11.9–30.3, and 14.7–34.5 mg kg⁻¹ for Cd, Pb, Cr, Zn, Cu, and Ni, respectively. The concentrations of heavy metals were maximum for Cd (0.41 ± 0.03 mg kg⁻¹), Pb (0.54 ± 0.11 mg kg⁻¹), Zn (14.4 ± 0.72 mg kg⁻¹), Cu (2.84 ± 0.27 mg kg⁻¹), and Ni (1.09 ± 0.11 mg kg⁻¹) in Cabbage and for Cr (2.63 ± 0.11 mg kg⁻¹) in green pepper. The result indicated that Cd has high transfer factor value and Pb was the lowest. The transfer pattern for heavy metals in different vegetables showed a trend in the order: Cd > Zn > Cu > Cr > Ni > Pb. Among different vegetables, cabbage showed the highest value of metal pollution index and bean had the lowest value. Hazard index of all the vegetables was less than unity; thus, the consumption of these vegetables is unlikely to pose health risks to the target population.
Mostrar más [+] Menos [-]Effects of supersaturation control strategies on hydroxyapatite (HAP) crystallization for phosphorus recovery from wastewater Texto completo
2017
Dai, Hongliang | Lu, Xiwu | Peng, Y. (Yonghong) | Yang, Zixuan | Zhsssu, Huaqing
The HAP crystallization for phosphorus removal from wastewater contributes to an environmental friendly production due to the fact that it helps reduce or eliminate the water eutrophication as well as increases the recovery of mineral resources. However, the generated microcrystalline with poor settleability in high levels of supersaturation solution has a negative effect on the phosphorus recovery efficiency. To overcome the drawback, multiple reagent feed ports (four feed ports) and different recirculation ratio (1.0, 1.5, 2.0, 2.5, 3.0) were investigated to control the levels of supersaturation in an air-agitated reactor with calcite as seeds. Results showed that the approach of multiple reagent feed ports could improve the conversion ratio of orthophosphate, but it had a limited effect (∼3% improvement) on phosphorus recovery efficiency (deposition on the seeds). With the increase of the recirculation ratio, the recovery efficiency was increased gradually and reached an optimal value of 85.63% under the recirculation ratio of 2.5 and four feed ports. This is because the adopted strategies could reduce the level of supersaturation by diluting the concentration of the reagents and inhibit large numbers of microcrystalline coinstantaneous occurrence. Meanwhile, the crystallized products were detected and analyzed by scanning electron micrograph (SEM) with energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD), which were proved to be HAP with a high purity. Collectively, these results demonstrated that supersaturation control using conventional approaches had a limited improvement on the phosphorus recovery efficiency in the form of HAP, and the new control strategies for supersaturation dispersion should be developed in the further study.
Mostrar más [+] Menos [-]Formetanate toxicity and changes in antioxidant enzyme system of Apis mellifera larvae Texto completo
2017
Staroň, Martin | Sabo, Rastislav | Sobeková, Anna | Sabova, Lucia | Legáth, Jaroslav | Lohajová, Ľuboslava | Javorský, Peter
Substantial percentage of world food production depends on pollinating service of honeybees that directly depends on their health status. Among other factors, the success of bee colonies depends on health of developed larvae. The crucial phase of larval development is the first 6 days after hatching when a worker larva grows exponentially and larvae are potentially exposed to xenobiotics via diet. In the present study, we determined the lethal concentration LC₅₀ (72 h) following single dietary exposure of honeybee larvae to formetanate under laboratory conditions, being also the first report available in scientific literature. Activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) were also measured in the homogenates of in vitro reared honeybee larvae after single formetanate exposure. Decreased specific activity of SOD and increased activities of CAT and GST suggest the induction of oxidative stress. Higher levels of thiobarbituric reactive species in all samples supported this fact. Comparing determined larval toxicity (LC₅₀ of 206.01 mg a.i./kg diet) with adult toxicity data, we can suppose that the larvae may be less sensitive to formetanate than the adult bees.
Mostrar más [+] Menos [-]Aqueous clay suspensions stabilized by alginate fluid gels for coal spontaneous combustion prevention and control Texto completo
2017
Qin, Botao | Ma, Dong | Li, Fanglei | Li, Yong
We have developed aqueous clay suspensions stabilized by alginate fluid gels (AFG) for coal spontaneous combustion prevention and control. Specially, this study aimed to characterize the effect of AFG on the microstructure, static and dynamic stability, and coal fire inhibition performances of the prepared AFG-stabilized clay suspensions. Compared with aqueous clay suspensions, the AFG-stabilized clay suspensions manifest high static and dynamic stability, which can be ascribed to the formation of a robust three-dimensional gel network by AFG. The coal acceleration oxidation experimental results show that the prepared AFG-stabilized clay suspensions can improve the coal thermal stability and effectively inhibit the coal spontaneous oxidation process by increasing crossing point temperature (CPT) and reducing CO emission. The prepared low-cost and nontoxic AFG-stabilized clay suspensions, exhibiting excellent coal fire extinguishing performances, indicate great application potentials in coal spontaneous combustion prevention and control.
Mostrar más [+] Menos [-]Toxicities of monoterpenes against housefly, Musca domestica L. (Diptera: Muscidae) Texto completo
2017
Zhang, Zhilin | Xie, Yongjian | Wang, Yong | Lin, Zhufeng | Wang, Lihua | Li, Guoyuan
The development of natural plant extracts and essential oils will assist to decrease the negative effects of synthetic chemicals. Many plant extracts and essential oils contain monoterpenes, sesquiterpenes, and aliphatic compounds. In the present study, the fumigation activity of 42 pure monoterpenes against housefly, Musca domestica, was evaluated. Results from fumigation tests revealed that ρ-cymene, terpinolene, (±)-menthol, thymol, carvacrol, (−)-carvone, (+)-camphor, (+)-pulegone, (−)-menthone, citral, (±)-citronellal, cuminaldehyde, and citronellyl acetate exhibited strong fumigation activity against M. domestica. Specifically, the compounds of (+)-pulegone, cuminaldehyde, citral, and ρ-cymene had a highest toxicity toward M. domestica with LC₅₀ values of 0.26, 0.60, 0.64, and 0.77 μl/L, respectively. The present results indicated that (+)-pulegone, cuminaldehyde, citral, and ρ-cymene are promising toxicants against M. domestica and could be useful in the search for new natural insecticides.
Mostrar más [+] Menos [-]The efficiency of Eichhornia crassipes in the removal of organic and inorganic pollutants from wastewater: a review Texto completo
2017
Mishra, Saurabh | Maiti, Abhijit
Water is a basic necessity of life, but due to overextraction and heavy input of nutrients from domestic and industrial sources, the contamination level of water bodies increase. In the last few decades, a potential interest has been aroused to treat wastewater by biological methodologies before discharge into the natural water bodies. Phytoremediation using water hyacinth is found to be an effective biological wastewater treatment method. Water hyacinth (Eichhornia crassipes), a notorious weed, being the most promising plant for removal of contaminants from wastewater is studied extensively in this regard. It has been successfully used to accumulate heavy metals, dyes, radionuclides, and other organic and inorganic contaminants from water at laboratory, pilot, and large scale. The plant materials are also being used as sorbent to separate the contaminant from water. Other than phytoremediation, the plant has been explored for various other purposes like ethanol production and generation of biogases and green manures. Such applications of this have been good support for the technocrats in controlling the growth of the plant. The present paper reviews the phytoremedial application of water hyacinth and its capability to remove contaminants in produced water and wastewater from domestic and isndustrial sources either used as a whole live plant grown in water or use of plant body parts as sorbent has been discussed.
Mostrar más [+] Menos [-]The knowledge, awareness, attitude and motivational analysis of plastic waste and household perspective in Malaysia Texto completo
2017
Afroz, Rafia | Rahman, Ataur | Masud, Muhammad Mehedi | Akhtar, Rulia
The focus of this study is to analyze the level of knowledge, awareness, and attitude toward plastic waste and to distinguish the key drivers that encourage the households in Kuala Lumpur, Malaysia, to participate in “No plastic campaign,” This study used the logistic regression model to explain the factors that may affect the willingness to participate (WTP) of households in the campaign. In this study, it is found that 35 % of households are willing to participate in the campaign. The results of the study also indicate that people who are more informed and more convinced of their knowledge have a more positive attitude toward recycling than their counterparts do. Furthermore, this study provides additional evidence of the level and classification of importance of motivating factors for plastic recycling, using the modified average and coefficient of variation of the models. From the analysis, the factor “helps reduce landfill use” is found as the most important factor and the factor of “raising money for charity” is found as the least important factor that motivates households to participate in recycling. The determinations of the study suggest some strategies that could hold implications for government and households to boost them to participate in the campaign “No Plastic Bag.”
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