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Coupling of bio-PRB and enclosed in-well aeration system for remediation of nitrobenzene and aniline in groundwater Полный текст
2016
A laboratory-scale bio-permeable reactive barrier (bio-PRB) was constructed and combined with enclosed in-well aeration system to treat nitrobenzene (NB) and aniline (AN) in groundwater. Batch-style experiments were first conducted to evaluate the effectiveness of NB and AN degradation, using suspension (free cells) of degrading consortium and immobilized consortium by a mixture of perlite and peat. The NB and AN were completely degraded in <3 days using immobilized consortium, while 3–5 days were required using free cells. The O₂ supply efficiency of an enclosed in-well aeration system was assessed in a box filled with perlite and peat. Dissolved O₂ (DO) concentrations increased to 8–12 mg L⁻¹ in 12 h for sampling ports within 12 cm of the aeration well. A diffusion coefficient as 33.5 cm² s⁻¹ was obtained. The DO concentration was >4 mg L⁻¹ when the aeration system was applied into the bio-PRB system. The NB and AN were effectively removed when the aeration system was functional in the bio-PRB. The removal efficiency decreased when the aeration system malfunctioned for 20 days, thus indicating that DO was an important factor for the degradation of NB and AN. The regain of NB and AN removal after the malfunction indicates the robustness of degradation consortium. No original organics and new formed by-products were observed in the effluent. The results indicate that NB and AN in groundwater can be completely mineralized in a bio-PRB equipped with enclosed in-well aeration system and filled with perlite and peat attached with degrading consortium.
Показать больше [+] Меньше [-]Speciation of potentially mobile Si in Yangtze Estuary surface sediments: estimates using a modified sequential extraction technique Полный текст
2016
Zhu, Huagang | Wang, Chao | Wang, Peifang | Hou, Jun | Qian, Jin | Ao, Yanhui | Liu, Cui
To improve our understanding of the Si-related biogeochemical processes that occur in estuarine ecosystems with large subaqueous deltas (e.g., the Yangtze Estuary; YE), the speciation of Si in the surface sediments of the YE was investigated. The relationships between the different Si species and sediment bulk parameters were also discussed. Based on modified sequential extraction method, we can successfully estimate the following five sedimentary potentially mobile Si pools: weak acid leachable Si (W-Si); Si bound to organic matter (H-Si); Si coprecipitated with amorphous Fe/Al oxides (O-Si); Si coprecipitated with crystalline Fe/Al oxides (Oᵤᵥ-Si), and biogenic silica (B-Si). The total potentially mobile Si pool (T-Si) ranged between 1689.31 and 5487.10 μg/g, with high values observed in deltaic mud deposits. The Si fractions were closely correlated with grain size compositions, except for O-Si. In deltaic mud deposits, efficient loss of organic matters and recycling of Fe oxides probably resulted in the amorphous or poorly crystalline Fe oxides uncoupled with the clay fractions, and thus leading to the lack of correlation between O-Si and grain size. As compared with Oᵤᵥ-Si, the O-Si should possess stronger mobility, which highlights the importance of quantifying the O-Si pool in deltaic sediments.
Показать больше [+] Меньше [-]EDTA and hydrochloric acid effects on mercury accumulation by Lupinus albus Полный текст
2016
Rodríguez, Luis | Alonso-Azcárate, Jacinto | Villaseñor, José | Rodríguez-Castellanos, Laura
The efficiency of white lupine (Lupinus albus) to uptake and accumulate mercury from a soil polluted by mining activities was assessed in a pot experiment with chemically assisted phytoextraction. The mobilizing agents tested were ethylenediaminetetracetic acid (EDTA) and hydrochloric acid (HCl). Two doses of each amendment were used (0.5 and 1.0 g of amendment per kg of soil), and unamended pots were used as a control. Addition of HCl to the soil did not negatively affect plant biomass, while the use of EDTA led to a significant decrease in plant growth when compared to that found for non-treated pots, with plants visually showing symptoms of toxicity. The addition of hydrochloric acid increased root, shoot and total plant Hg uptake of white lupine by 3.7 times, 3.1 times and 3.5 times, respectively, in relation to non-amended plants. The greatest efficiency was obtained for the highest HCl dose. EDTA led to higher concentrations of total plant Hg than that found with the control, but, due to the aforementioned decrease in plant biomass, the Hg phytoextraction yield was not significantly increased. These results were attributed to the capability of both amendments to form stable Hg complexes. The concentration of Hg in the water of the soil pores after the phytoextraction experiment was very low for all treatments, showing that risks derived from metal leaching could be partially avoided by using doses and chemicals suitable to the concentration of metal in the soil and plant performance.
Показать больше [+] Меньше [-]Optimizing the position of insulating materials in flat roofs exposed to sunshine to gain minimum heat into buildings under periodic heat transfer conditions Полный текст
2016
Shaik, Saboor | Talanki, Ashok Babu Puttranga Setty
Building roofs are responsible for the huge heat gain in buildings. In the present work, an analysis of the influence of insulation location inside a flat roof exposed directly to the sun’s radiation was performed to reduce heat gain in buildings. The unsteady thermal response parameters of the building roof such as admittance, transmittance, decrement factor, and time lags have been investigated by solving a one-dimensional diffusion equation under convective periodic boundary conditions. Theoretical results of four types of walls were compared with the experimental results available in literature. The results reveal that the roof with insulation placed at the outer side and at the center plane of the roof is the most energy efficient from the lower decrement factor point of view and the roof with insulation placed at the center plane and the inner side of the roof is the best from the highest time lag point of view among the seven studied configurations. The composite roof with expanded polystyrene insulation located at the outer side and at the center plane of the roof is found to be the best roof from the lowest decrement factor (0.130) point of view, and the composite roof with resin-bonded mineral wool insulation located at the center plane and at the inner side of the roof is found to be energy efficient from the highest time lag point (9.33 h) of view among the seven configurations with five different insulation materials studied. The optimum fabric energy storage thicknesses of reinforced cement concrete, expanded polystyrene, foam glass, rock wool, rice husk, resin-bonded mineral wool, and cement plaster were computed. From the results, it is concluded that rock wool has the least optimum fabric energy storage thickness (0.114 m) among the seven studied building roof materials.
Показать больше [+] Меньше [-]Power generation by high head water in a building using micro hydro turbine—a greener approach Полный текст
2016
M. M. S. R. S., Bhargav | V., Ratna Kishore | S. P., Anbuudayasankar | K., Balaji
Demand for green energy production is arising all over the world. A lot of emphasis is laid in making the buildings green. Even a small amount of energy savings made contribute to saving the environment. In this study, an idea is proposed and studied to extract power from the high head water in the pipelines of a building. A building of height 15 m is considered for this study. Water flowing in the pipe has sufficient energy to run a micro hydro turbine. The feasibility of producing electrical energy from the energy of pipe water is found. The motivation is to find the feasibility of generating power using a low-cost turbine. The experimental setup consists of micro turbine of 135 mm diameter coupled to a 12-V DC generator; LEDs and resistors are employed to validate the results. The theoretical calculations were presented using the fundamental equations of fluid mechanics. The theoretical results are validated using experimental and numerical results using CFD simulation. In addition, exergy analysis has been carried out to quantify the irreversibilities during the process in the system.
Показать больше [+] Меньше [-]Short-term association between particular matter air pollution and pediatric clinical visits for wheezing in a subarea of Shanghai Полный текст
2016
Shan, Wenjie | Lu, Yanming | Guo, Yinshi | Li, Yaqin | Xu, Lingyun | Cao, Lanfang
To assess the association between the concentration of ambient particulate matter (PM) and the pediatric clinical visits for wheezing among children under 3 years old, data of daily air pollutants (PM₂.₅, PM₁₀, NO₂, SO₂, CO), meteorological reports, along with the number of daily clinical visits of the children with wheezing at the Pediatric Department of Shanghai Renji Hospital (South Campus) were collected from January through December 2014. Correlation between the levels of air pollutants and the number of clinical patients for wheezing were analyzed by a time series analysis with a generalized addictive model (GAM). During the study period, the daily average concentrations of PM₂.₅, PM₁₀, NO₂, SO₂, and CO were 51.84 ± 32.51, 72.69 ± 41.15, 43.25 ± 18.07, 17.45 ± 10.42, and 0.82 ± 0.26 μg/m³, respectively, which were abnormally higher compared to the standard defined by the Chinese Ministry of Environment Protection. The average number of daily clinical patients with wheezing was 23 ± 14 persons/day. The number of clinical visit by children with wheezing was significantly correlated with concentration of PM₂.₅ or PM₁₀ when the effect of SO₂ and NO₂ was adjusted (P < 0.05). It was also found that exposure-response relationship was a linear non-threshold mode when it was analyzed by the GAM, and the percent of the clinical visits of children with wheezing increased from 0 to nearly 20 % with every interquartile increase of PM₂.₅. The visiting number of children at a pediatric outpatient clinic increased due to the increase of PM₂.₅ in Pujiang, Shanghai, China.
Показать больше [+] Меньше [-]Hydrogen storage studies on palladium-doped carbon materials (AC, CB, CNMs) @ metal–organic framework-5 Полный текст
2016
Viditha, V. | Srilatha, K. | Himabindu, V.
Metal organic frameworks (MOFs) are a rapidly growing class of porous materials and are considered as best adsorbents for their high surface area and extraordinary porosity. The MOFs are synthesized by using various chemicals like triethylamine, terepthalic acid, zinc acetate dihydrate, chloroform, and dimethylformamide (DMF). Synthesized MOFs are intercalated with palladium/activated carbon, carbon black, and carbon nanomaterials by chemical reduction method for the purpose of enhancing the hydrogen adsorption capacities. We have observed that the palladium doped activated carbon on MOF-5 showed high hydrogen storage capacity. This may be due to the affinity of the palladium toward hydrogen molecule. The samples are characterized by X-ray diffraction, scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. We have observed a clear decrease in the BET surface area and pore volume. The obtained results show a better performance for the synthesized sample. To our best knowledge, no one has reported the work on palladium-doped carbon materials (activated carbon, carbon black, carbon nanomaterials) impregnated to the metal–organic framework-5. We have attempted to synthesize carbon nanomaterials using indigenously fabricated chemical vapor deposition (CVD) unit as a support. We have observed an increase in the hydrogen storage capacities.
Показать больше [+] Меньше [-]Quality of the Solimões River water for domestic use by the riverine community situated in Manacapuru-Amazonas-Brazil Полный текст
2016
Pantoja, N. G. P. | Castro, L. M. | Rocha, S. D. | Silva, J. A. | Ribeiro, J. S. P. | Donald, A. R. | Silva, L. M. | Oliveira, T. C. S.
The Amazon has the largest watershed in the world, with abundant fresh water reserves. Such abundance contrasts with the quality of the water consumed in the riverine communities. This work highlights the importance of assessing the quality of water of the Solimões River in the stretch situated opposite the Community Nossa Senhora das Graças-Costa do Pesqueiro, in front of the town of Manacapuru-Amazonas-Brazil. The research aimed to evaluate environmental indicators for the quality of the river water as well as in households in this community, according to the regional seasonality. The monitored parameters such as conductivity, dissolved oxygen, turbidity, color, pH, nitrate, nitrite, and sulfate were compared with the water quality standards in force in Brazil. Values well above the maximum level allowed (MLA) for color and turbidity parameters were found in some households, indicating that the water collected from the river is not getting appropriate treatment. The analysis of the correlation matrix of the parameters in the flood period of the river evidenced high correlation among dissolved oxygen (D.O), NO₃ ⁻, Cl⁻, SO₄ ²⁻, and color. In this study, by principal component analysis (PCA), it was observed that the characteristics of the water, obtained from the river to be consumed in the households, in the flood period showed similarities with the river water samples, indicating absence of efficient treatment for human consumption.
Показать больше [+] Меньше [-]Eco-friendly drugs from the marine environment: spongeweed-synthesized silver nanoparticles are highly effective on Plasmodium falciparum and its vector Anopheles stephensi, with little non-target effects on predatory copepods Полный текст
2016
Mosquitoes act as vectors of devastating pathogens and parasites, representing a key threat for millions of humans and animals worldwide. The control of mosquito-borne diseases is facing a number of crucial challenges, including the emergence of artemisinin and chloroquine resistance in Plasmodium parasites, as well as the presence of mosquito vectors resistant to synthetic and microbial pesticides. Therefore, eco-friendly tools are urgently required. Here, a synergic approach relying to nanotechnologies and biological control strategies is proposed. The marine environment is an outstanding reservoir of bioactive natural products, which have many applications against pests, parasites, and pathogens. We proposed a novel method of seaweed-mediated synthesis of silver nanoparticles (AgNP) using the spongeweed Codium tomentosum, acting as a reducing and capping agent. AgNP were characterized by UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). In mosquitocidal assays, the 50 % lethal concentration (LC₅₀) of C. tomentosum extract against Anopheles stephensi ranged from 255.1 (larva I) to 487.1 ppm (pupa). LC₅₀ of C. tomentosum-synthesized AgNP ranged from 18.1 (larva I) to 40.7 ppm (pupa). In laboratory, the predation efficiency of Mesocyclops aspericornis copepods against A. stephensi larvae was 81, 65, 17, and 9 % (I, II, III, and IV instar, respectively). In AgNP contaminated environment, predation was not affected; 83, 66, 19, and 11 % (I, II, III, and IV). The anti-plasmodial activity of C. tomentosum extract and spongeweed-synthesized AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. Fifty percent inhibitory concentration (IC₅₀) of C. tomentosum were 51.34 μg/ml (CQ-s) and 65.17 μg/ml (CQ-r); C. tomentosum-synthesized AgNP achieved IC₅₀ of 72.45 μg/ml (CQ-s) and 76.08 μg/ml (CQ-r). Furthermore, low doses of the AgNP inhibited the growth of Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi, using the agar disk diffusion and minimum inhibitory concentration protocol. Overall, C. tomentosum metabolites and spongeweed-synthesized AgNP may be potential candidates to develop novel and effective tools in the fight against Plasmodium parasites and their mosquito vectors. The employ of ultra-low doses of nanomosquitocides in synergy with cyclopoid crustaceans seems a promising green route for effective mosquito control programs.
Показать больше [+] Меньше [-]The removal of organic precursors of DBPs during three advanced water treatment processes including ultrafiltration, biofiltration, and ozonation Полный текст
2016
The removal efficiency of organic matter, the formation potential of trihalomethanes (THMFP), and the formation potential of haloacetic acids (HAAFP) in each unit of three advanced treatment processes were investigated in this paper. The molecular weight distribution and the components of organic matter in water samples were also determined to study the transformation of organic matter during these advanced treatments. Low-molecular-weight matter was the predominant fraction in raw water, and it could not be removed effectively by ultrafiltration and biofiltration. The dominant species of disinfection by-product formation potential (DBPFP) in raw water were chloroform and monochloroacetic acid (MCAA), with average concentrations of 107.3 and 125.9 μg/L, respectively. However, the formation potential of chloroform and MCAA decreased to 36.2 and 11.5 μg/L after ultrafiltration. Similarly, biological pretreatment obtained high removal efficiency for DBPFP. The total THMFP decreased from 173.8 to 81.8 μg/L, and the total HAAFP decreased from 211.9 to 84.2 μg/L. Separate ozonation had an adverse effect on DBPFP, especially for chlorinated HAAFP. Numerous low-molecular-weight compounds such as aldehydes, ketones, and alcohols were generated during the ozonation, which have been proven to be important precursors of HAAs. However, the ozonation/biological activated carbon (BAC) combined process had a better removal efficiency for DBPFP. The total DBPFP decreased remarkably from 338.7 to 113.3 μg/L after the O₃/BAC process, far below the separated BAC of process B (189.1 μg/L).
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