细化搜索
结果 1891-1900 的 3,243
Factors affecting the adsorptive removal of bisphenol A in landfill leachate by high silica Y-type zeolite
2015
Chen, Xiaoqiang | Fujiwara, Taku | Fukahori, Shuji | Ishigaki, Tomonori
Although bisphenol A (BPA), a representative endocrine-disrupting compound, has been detected frequently in landfill leachate, effective technologies for BPA removal from landfill leachates are limited. We used high silica Y-type zeolite (HSZ-385) for the selective adsorption of BPA from landfill leachate, and factors affecting this adsorption are discussed. Higher removal efficiencies at pH 5.0–9.0 imply that neutral BPA is adsorbed more easily onto HSZ-385 than monomeric or divalent BPA anions. An increase in ionic strength and sodium acetate concentration did not affect BPA adsorption significantly, while the removal efficiency decreased slightly when more than 50 mgC/L of humic acid was added. HSZ-385 was applied to synthetic leachates that simulate the composition of landfill leachate at various degradation stages. In young acidic leachates that contain sodium acetate, the use of HSZ-385 for the adsorptive removal of BPA appears to be more effective than in old alkaline leachates, which contain large amounts of humic acid. In addition, 82 % BPA removal was achieved from young raw leachates using HSZ-385, which demonstrates that selective BPA removal from actual landfill leachate has been achieved.
显示更多 [+] 显示较少 [-]Managing produced water from coal seam gas projects: implications for an emerging industry in Australia
2015
Davies, Peter J. | Gore, Damian B. | Khan, Stuart J.
This paper reviews the environmental problems, impacts and risks associated with the generation and disposal of produced water by the emerging coal seam gas (CSG) industry and how it may be relevant to Australia and similar physical settings. With only limited independent research on the potential environmental impacts of produced water, is it necessary for industry and government policy makers and regulators to draw upon the experiences of related endeavours such as mining and groundwater extraction accepting that the conclusions may not always be directly transferrable. CSG is widely touted in Australia as having the potential to provide significant economic and energy security benefits, yet the environmental and health policies and the planning and regulatory setting are yet to mature and are continuing to evolve amidst ongoing social and environmental concerns and political indecision. In this review, produced water has been defined as water that is brought to the land surface during the process of recovering methane gas from coal seams and includes water sourced from CSG wells as well as flowback water associated with drilling, hydraulic fracturing and gas extraction. A brief overview of produced water generation, its characteristics and environmental issues is provided. A review of past lessons and identification of potential risks, including disposal options, is included to assist in planning and management of this industry.
显示更多 [+] 显示较少 [-]The impact of aluminum, fluoride, and aluminum–fluoride complexes in drinking water on chronic kidney disease
2015
Wasana, Hewa M. S. | Perera, Gamage D. R. K. | De Gunawardena, Panduka S. | Bandara, Jayasundera
It is suspected that drinking water containing fluoride and aluminum results in negative health effects especially on brain, liver, and kidney. In this investigation, the effect of F, Al, and AlFₓ complex on chronic kidney disease (CKD) was investigated. Mice were treated either with WHO recommended or slightly higher F and Al levels in drinking water. Treatment solutions contained 0.05–10.0 mg/L of F, 0.08–10.0 mg/L of Al, or 0.07–15 mg/L of AlFₓ, and the treatment period was 42 weeks. Blood urea level and creatinine levels were investigated as a measure of malfunction of kidneys. Histopathological evaluations of kidney tissues were carried out to assess the extent of damage that F, Al, and AlFₓ complex could cause. It was demonstrated that the treated drinking water containing F and Al with par with WHO or moderately above the WHO levels or AlFₓ in low level (0.07–15 mg/L) does not lead to CKD in mice.
显示更多 [+] 显示较少 [-]Anaerobic treatability of liquid residue from wet oxidation of sewage sludge
2015
Bertanza, Giorgio | Galessi, Raniero | Menoni, Laura | Pedrazzani, Roberta | Salvetti, Roberta | Zanaboni, Sabrina
Wet Oxidation (WO) of sewage sludge is a chemical oxidation of sludge at high temperatures and pressures by means of an oxygen-containing gas. The liquid stream originated by WO is easily biodegradable, and therefore, the recirculation to the biological Waste Water Treatment Plant (WWTP) may be a feasible solution. However, the WO effluent has a residual organic and nitrogen content so that its treatment may be required when the receiving WWTP has no surplus treatment capacity left. The aim of this research was the assessment of the anaerobic treatability of the WO liquid residue, in order to reduce the organic load to be recirculated to the WWTP, simultaneously promoting energy recovery. For this purpose, the liquid residue obtained during full scale WO tests on two different types of sludge was submitted to anaerobic digestion in a continuous flow pilot reactor (V = 5 L). Furthermore, batch tests were carried out in order to evaluate possible inhibition factors. Experimental results showed that, after the start-up/acclimation period (~130 days), Chemical Oxygen Demand (COD) removal efficiency was stably around 60 % for about 120 days, despite the change in operating conditions. In the last phase of the experimental activity, COD removal reached 70 % under the following treatment conditions: Hydraulic Retention Time (HRT) = 20 days, Volumetric Organic Loading Rate (VOLR) = 0.868 kg COD/m³/day, Organic Loading Rate per Volatile Suspended Solids (OLRᵥₛₛ) = 0.078 kg COD/kg VSS/day, temperature (T) = 36.5 °C, pH = 8. Energy balance calculation demonstrated anaerobic treatment sustainability.
显示更多 [+] 显示较少 [-]Techno-economic and environmental assessment of sewage sludge wet oxidation
2015
Bertanza, Giorgio | Canato, Matteo | Heimersson, Sara | Laera, Giuseppe | Salvetti, Roberta | Slavik, Edoardo | Svanström, Magdalena
Today, several technologies and management strategies are proposed and applied in wastewater treatment plants (WWTPs) to minimise sludge production and contamination. In order to avoid a shifting of burdens between different areas, their techno-economic and environmental performance has to be carefully evaluated. Wet oxidation (WO) is an alternative solution to incineration for recovering energy in sewage sludge while converting it to mostly inorganic residues. This paper deals with an experimentation carried out within the EU project “ROUTES”. A mass balance was made for a WWTP (500,000 person equivalents) in which a WO stage for sludge minimisation was considered to be installed. Both bench- and full-scale test results were used. Design of treatment units and estimation of capital and operational costs were then performed. Subsequently, technical and economic aspects were evaluated by means of a detailed methodology which was developed within the ROUTES project. Finally, an assessment of environmental impacts from a life cycle perspective was performed. The integrated assessment showed that for the specific upgrade considered in this study, WO technology, although requiring a certain increase of technical complexity at the WWTP, may contribute to environmental and economic advantages. The paper provides guidance in terms of which aspects need a more thorough evaluation in relation to the specific case in which an upgrade with WO is considered.
显示更多 [+] 显示较少 [-]Spatial and seasonal variability of pico-, nano- and microphytoplankton at the bottom seawater in the north coast of Sfax, Eastern Mediterranean Sea
2015
Rekik, Amira | Denis, Michel | Maalej, Sami | Ayadi, Habib
In the frame of the Taparura Project, we studied the distribution of pico-, nano- and microphytoplankton communities in relation to environmental variables at 18 stations sampled during four coastal cruises conducted between October 2009 and July 2010 at the bottom, on the north coast of Sfax (Tunisia, Eastern Mediterranean Sea). The restoration effect on coastal ultraphytoplankton (<10 μm) and microphytoplankton (<200 μm) was investigated using conventional flow cytometry and inverted microscopy. Flow cytometry analysis of ultraphytoplankton resolved six groups (Prochlorococcus, Synechococcus, nanoeukaryotes and three distinct subgroups within picoeukaryotes). In addition to these autotrophic groups, two unknown groups were characterised on the north coast. Picophytoplankton abundance shifted from a summer dominance of Synechococcus to a dominance of picoeukaryotes and Prochlorococcus during spring. Nanoeukaryotes were the most abundant in spring. Microphytoplankton was resolved into five groups, labelled Bacillariophyceae, Dinophyceae, Cyanobacteriae, Euglenophyceae and Chlorophyceae. A total of 90 microphytoplankton species were identified in all stations, with an overwhelming abundance of large diatoms, a typical trait of benthic communities (Coscinodiscus sp., Grammatophora sp., Navicula sp., Pleurosigma sp., Striatella unipunctata …). Results collected in this study are favouring a beneficial impact on the ecosystem of the Sfax north coast restoration achieved by the Taparura Project.
显示更多 [+] 显示较少 [-]Pb(II), Cr(VI) and atrazine sorption behavior on sludge-derived biochar: role of humic acids
2015
Zhou, Fengsa | Wang, Hong | Fang, Sheng’en | Zhang, Weihua | Qiu, Rongliang
Pyrolyzing municipal wastewater treatment sludge into biochar can be a promising sludge disposal approach, especially as the produced sludge-derived biochar (SDBC) is found to be an excellent sorbent for heavy metals and atrazine. The aim of this study was to investigate how and why the coexisting humic acids influence the sorption capacity, kinetic, and binding of these contaminants on SDBC surface. Results showed humic acids enhanced Pb(II)/Cr(VI) sorption binding, and increased the corresponding Pb(II) Langmuir sorption capacity at pH 5.0 from 197 to 233 μmol g⁻¹, and from 688 to 738 μmol g⁻¹ for Cr(VI) at pH 2.0. It can be mainly attributed to the sorbed humic acids, whose active functional groups can offer the additional sites to form stronger inner-sphere complexes with Pb²⁺, and supply more reducing agent to facilitate the transformation of Cr(VI) to Cr(III). However, humic acids reduced the atrazine adsorption Freundlich constant from 1.085 to 0.616 μmol g⁻¹. The pore blockage, confirmed by the decreased BET-specific surface area, as well as the more hydrophilic surface with more sorbed water molecules may be the main reasons for that suppression. Therefore, the coexisting humic acids may affect heavy metal stabilization or pesticide immobilization during SDBC application to contaminated water or soils, and its role thus should be considered especially when organic residues are also added significantly to increase the humic acid content there.
显示更多 [+] 显示较少 [-]Decomposition of birch leaves in heavily polluted industrial barrens: relative importance of leaf quality and site of exposure
2015
Kozlov, Mikhail V. | Zvereva, Elena L.
The decrease in litter decomposition rate in polluted habitats is well documented, but the factors that explain the observed variation in the magnitude of this pollution effect on litter decomposition remain poorly understood. We explored effects of environmental conditions and leaf quality on decomposition rate of mountain birch (Betula pubescens ssp. czerepanovii) leaves in a heavily polluted industrial barren near the nickel-copper smelter at Monchegorsk. Litter bags filled with leaves collected from two heavily polluted barren sites and from two control forest sites were buried at 2.5-cm depth and exposed for 2 and 4 years at each of these four sites. The relative mass loss of native leaves in the industrial barren during 2 years of exposure was reduced to 49 % of the loss observed in the unpolluted forest. We found a similar reduction in mass loss when leaves from control sites were exposed to polluted sites and when leaves from polluted sites were exposed to control sites. We conclude that the reduction in leaf litter decomposition in an industrial barren is caused by pollution-induced changes in both environmental conditions and leaf quality. This reduction is much smaller than expected, given the four-fold decrease in soil microbial activity and nearly complete extinction of saprophagous invertebrates in the polluted soil. We suggest that a longer snowless period and higher spring and summer temperatures at the barren sites have partially counterbalanced the adverse effects caused by the toxicity of metal pollutants.
显示更多 [+] 显示较少 [-]Phytoremediation of cadmium by the facultative halophyte plant Bolboschoenus maritimus (L.) Palla, at different salinities
2015
Santos, Márcia S. S. | Pedro, Carmen A. | Gonçalves, Sílvia C. | Ferreira, Susana M. F.
The cadmium phytoremediation capacity of the halophyte plant Bolboschoenus maritimus (L.) Palla and the influence of water salinity were assessed in a greenhouse experiment, in order to better understand the bioremediation capacity of this plant. Three concentrations of cadmium (0, 50 and 100 μg l⁻¹) and four salinity conditions (0, 5, 10 and 20) were chosen to evaluate the cadmium accumulation, in order to test these plants as a potential phytoremediation tool in brackish environments. The cadmium content in water and plants (underground organs, stems and leaves) was analysed with graphite furnace atomic absorption spectrometry. All the plants submitted to salinity 20 and in the three cadmium treatments died. The plants’ survival was highest in the lowest salinities, where highest growth and biomasses were also obtained. The plants presented more cadmium content in the rhizomes, followed by stems and even less in leaves. The salt stress of the plants interfered with their cadmium accumulation capacity. The highest cadmium accumulation in the rhizomes occurred at salinity 0, while the salinities 0 and 5 were the most adequate for stems and leaves. The experiment pointed out that B. maritimus represents a good possible intervenient for cadmium bioremediation in freshwater and low salinity brackish water environments, but its use is limited in the habitats of higher salinity.
显示更多 [+] 显示较少 [-]Effects of permissible maximum-contamination levels of VOC mixture in water on total DNA, antioxidant gene expression, and sequences of ribosomal DNA of Drosophila melanogaster
2015
Doganlar, Oguzhan | Doganlar, Zeynep Banu | Tabakcioglu, Kiymet
In this study, we aimed to investigate the mutagenic and carcinogenic potential of a volatile organic compound (VOC) mixture with references to the response of D.melanogaster using selected antioxidant gene expressions, RAPD assay and base-pair change of ribosomal 18S, and the internal transcribed spacer, ITS2 rDNA gene sequences. For this purpose, Drosophila melanogaster Oregon R, reared under controlled conditions on artificial diets, were treated with the mixture of thirteen VOCs, which are commonly found in water in concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. In the random amplified polymorphic DNA (RAPD) assay, band changes were clearly detected, especially at the 50 and 75 ppb exposure levels, for both treatment periods, and the band profiles exhibited clear differences between the treated and untreated flies with changes in band intensity and the loss/appearance of bands. Quantitative real-time PCR (qRT-PCR) analysis of Mn-superoxide dismutase (Mn-SOD), catalase (CAT) and glutathione-synthetase (GS) expressions demonstrated that these markers responded significantly to VOC-induced oxidative stress. Whilst CAT gene expressions increased linearly with increasing concentrations of VOCs and treatment times, the 50- and 75-ppb treatments caused decreases in GS expressions compared to the control at 5 days. Treatment with VOCs at both exposure times, especially in high doses, caused gene mutation of the 18S and the ITS₂ ribosomal DNA. According to this research, we thought that the permissible maximum-contamination level of VOCs can cause genotoxic effect especially when mixed.
显示更多 [+] 显示较少 [-]