خيارات البحث
النتائج 2341 - 2350 من 4,935
Characteristic of adsorption cadmium of red soil amended with a ferromanganese oxide-biochar composite النص الكامل
2019
Zhou, Qiwen | Liao, Bohan | Lin, Lina | Song, Zhengguo | Khan, Zulqarnain Haider | Lei, Ming
The increasing scarcity of arable land necessitates the development of effective decontamination techniques to re-gain contaminated areas and make them suitable for agricultural and other activities. Herein, we prepare a ferromanganese binary oxide-biochar composite (FMBC) and compare its potential for remediating Cd-contaminated red soil with that of biochar (BC), showing that (i) the obtained adsorption data are well described by the Langmuir model and (ii) Cd adsorption capacity increases with increasing adsorbent dosage. Specifically, the Cd adsorption capacity of FMBC-amended soil (6.72 mg g⁻¹) is demonstrated to significantly exceed that of BC-amended red soil (4.85 mg g⁻¹) and that of the control (2.28 mg g⁻¹) and increases with increasing temperature and pH, while the results of instrumental analyses indicate that Cd sorption on the soil surface occurs via the formation of CdO and Cd(OH)₂. Thus, FMBCs are concluded to play an important role in the adsorption of Cd, having the potential to prevent red soil acidification and improve soil quality, and are found to be promising remediation materials for mitigating the risks posed by Cd-contaminated red soil.
اظهر المزيد [+] اقل [-]Consumers’ knowledge, attitude and behavioural patterns towards the liquid wastes (cooking oil) in Istanbul, Turkey النص الكامل
2019
Gurbuz, Ismail Bulent | Ozkan, Gulay
This study was carried out to reveal the people’s knowledge level about the harmful effects of waste oils, especially waste cooking oil, on the environment. It also aims to understand the attitude and behavioural patterns related to the safe disposal of them. Istanbul is chosen because it represents the entire country with its diverse socio-demographic and socio-cultural structure. A total of 408 respondents were randomly chosen and interviewed in the designated regions. The research data were obtained by using a structured survey consisting demographic and Likert scale questions. SPSS 23.0 statistical software was used to analyse the survey data. Results suggest that despite the high educational level, participants did not know that household liquid waste has a negative impact on the environment. They disagreed on the statement that liquid waste can damage water resources. Public spots, and formal and informal education were not found effective and failed to make the desired impact. Majority of participants did not know their duties in the disposal of waste. They also did not know where the liquid waste collection units were and what projects were being implemented in their neighbourhood. Fewer participants were concerned at what point and how the hazardous liquid wastes collected by municipalities were disposed of after leaving their habitat and whether these methods were reliable or acceptable. This research concludes that user behaviour was disappointing in cooking oil usage and waste oil disposal. The collection of waste cooking oils remains far below the developed countries.
اظهر المزيد [+] اقل [-]A dualistic water cycle system dynamic model for sustainable water resource management through progressive operational scenario analysis النص الكامل
2019
Peng, Jiayu | Lu, Shaoyong | Cao, Yimei | Wang, Xing | Hu, Xiaozhen | Wang, Minghao | Zheng, Binghui
A reliable system simulation of the reciprocal mechanism between water resource utilization and dualistic water cycle is essential to the basin water resource sustainability management. In this study, a system dynamic model was built to simulate the water cycle change and lake water environmental pressure under the influence of water resources utilization, and the procedure of a progressive operational scenario analysis of how to relieve water environment pressure was illustrated. Dianchi Lake, which is the sixth largest and the most severely polluted freshwater lake in China, was employed as a case study to demonstrate the applicability of the model. The change of runoff components and pollution load of total nitrogen from 2000 to 2030 were discussed. Also, the sustainable water resource management was ultimately realized in the planning period through three progressive levels of water resource regulation scenarios. Compared with business-as-usual scenario, the TN pollution load into lake and total water demand decrease by 27.1 and 27.3%, and the domestic water use, industry water use, tertiary industry water use, and irrigation decrease 9.0, 16.8, 29.5, and 30% in the scenario 3.
اظهر المزيد [+] اقل [-]Effects of Mixed Surfactant on Enhancing High Concentration Anthracene and Pyrene Removal from Contaminated Soil النص الكامل
2019
Yang, Min | Ke, Junfeng | Zhang, Qiwu | He, Xiaoman
Surfactants are considered promising and practical substances for enhancing polycyclic aromatic hydrocarbon (PAHs) removal from contaminated soil. In order to explore the effects of single and mixed surfactants on the removal of high-concentration PAHs from soil, a series of experiments have been conducted. In this study, Tween80-saponin (a mixed surfactant), Tween80 (a nonionic surfactant), and saponin (a biosurfactant) were used to remove two typical and high concentration PAHs (anthracene and pyrene) from contaminated soil. Results showed that the mixed surfactant had better performance on the solubilization of anthracene and pyrene than Tween80, but its performance was worse than saponin. When the proportion and concentration of the mixed surfactant were 1:9 and 800 mg L⁻¹ respectively, the elution rate of anthracene could reach 97.67%, it was better than that by Tween80 and saponin. In addition, the Tween80-saponin mixed surfactant had good performance on actual PAHs contaminated soil remediation. When the proportion and concentration of Tween80-saponin were 1:9 and 800 mg L⁻¹ respectively, the PAHs elution rate of actual contaminated soil could reach 81.31%.
اظهر المزيد [+] اقل [-]Discovery and mechanism study of a novel chromium-accumulating plant, Lonicera japonica Thunb النص الكامل
2019
Meng, Fanxu | Gao, Yuan | Feng, Qingyuan
Finding chromium-accumulating plants is of great interest for phytoremediation of soil contaminated by chromium (Cr). Inspired by Traditional Chinese Medicine, we examined the Cr-resistance and Cr-accumulation of Lonicera japonica Thunb. After a two-phase study using both soil and water culture, we found that L. japonica could be a novel Cr-accumulating plant, which contains an average Cr(III) content of 1297.14 mg.kg⁻¹ in its leaves. The Cr enrichment factor and the Cr transport coefficient of Lonicera japonica was 5.19 and 1.79, respectively. Lonicera japonica is the fifth Cr-accumulating plant discovered worldwide, and the first Cr-accumulating woody plant ever discovered. The results support the conclusions drawn from studies of Cr-accumulating Leersia hexandra that oxalic acid production can increase Cr tolerance whereas citric acid or malic acid has no effect, suggesting that oxalic acid might be a common reason for Cr tolerance in all Cr-accumulating plants. Moreover, this study revealed that the production of anthocyanin and carotene can also increase Cr(III) tolerance, suggesting that anthocyanin and carotene might also account for Cr tolerance in Cr-accumulating plants. We believe that the discovery of Lonicera japonica as a Cr-accumulating plant will offer great opportunities in phytoremediation, and the success should be a strong sign that Traditional Chinese Medicine harbors more secrets to be uncovered with modern science.
اظهر المزيد [+] اقل [-]Modeling and performance improvement of an anaerobic–anoxic/nitrifying-induced crystallization process via the multi-objective optimization method النص الكامل
2019
Dai, Hongliang | Chen, Wenliang | Peng, Lihong | Wang, Xingang | Lu, Xiwu
The trade-off between energy savings and emission reductions of an activated sludge process is a multi-objective problem relating to several potentially conflicting objectives. Therefore, the optimal modification of an anaerobic–anoxic/nitrifying/induced crystallization (A2N-IC) process by multi-objective optimization method was studied in this work. The multi-objective optimization model comprised three evaluative indices, (effluent quality (EQ), operation cost (OC), and total volume (TV) of structures), and 14 process parameters (decision variables) solving by non-dominated sorting genetic algorithm II (NSGA-II) in MATLAB. The trade-off relationships among EQ, OC, and TV were investigated under 30 days of dynamic influent with different constraint conditions. A series of Pareto solutions were obtained, and one Pareto solution was selected for further analysis. Results showed improved effluent concentrations of chemical oxygen demand (COD), total nitrogen (TN), ammonia-nitrogen (NH₄⁺-N), and total phosphorous (TP) under the optimized strategy compared to the original strategy, where the average effluent concentrations decreased by 2.22, 0.47, 0.13, and 0.02 mg/L, respectively. The values of EQ and OC decreased from 0.015 kg/day and 0.15 ¥/m³ to 0.0023 kg/day and 0.12 ¥/m³, respectively, while the TV increased from 0.31 to 0.33 m³. These results indicated that the multi-objective optimization method is useful for modifying activated sludge processes.
اظهر المزيد [+] اقل [-]Multi-response optimization to obtain better performance and emission level in a diesel engine fueled with water-biodiesel emulsion fuel and nanoadditive النص الكامل
2019
Vellaiyan, Suresh | Subbiah, Arunkumar | Chockalingam, Prabha
The present study aims to investigate the optimum condition of stationary diesel engine’s operating parameters to obtain better performance and emission level, where the diesel engine is fueled with different concentrations of soybean biodiesel (SB), water, and alumina (Al) nanoadditive. Taguchi method coupled with gray relational analysis has been implemented in this study to obtain the optimum concentration of SB, water, and Al nanoparticle, and statistical analysis of variance (ANOVA) is applied to obtain the individual response of operating parameters on overall engine performance and emission level. Various concentration of SB (10%, 20%, and 30%), water (10%, 20%, and 30%), and Al nanoparticle (50 ppm, 100 ppm, and 150 ppm) are mixed with base diesel (BD) by mechanical agitation and followed by an ultra-sonication process. The fuel properties are measured based on EN590 standards, and the experiments are conducted in a single-cylinder, four-stroke, natural aspirated stationary diesel engine based on an L₉ orthogonal array fuel combination. From the obtained gray relational co-efficient (GRC) and signal-to-noise (S/N) ratio, the optimum concentration of SB, water, and nanoadditive are identified as 20%, 10%, and 100 ppm, respectively, and a confirmation experiment has also been carried out to confirm the improvements at optimum condition. The ANOVA results imply that water concentration (WC) has the maximum influence on overall diesel engine’s performance and emission level followed by nanoparticle and SB concentrations. Overall, it can be concluded that the engine exhibits better performance and greener emissions at optimal condition.
اظهر المزيد [+] اقل [-]Discharge of biocidal products from healthcare activities into a sewage system—a case study at a French university hospital النص الكامل
2019
Lasek, Florence | Karpel Vel Leitner, Nathalie | Rauwel, Gaëtan | Blanchier, Ludovic | Castel, Olivier | Ayraud-Thevenot, Sarah | Deborde, Marie
This study focused on the presence of three biocidal products specific to healthcare facilities, i.e. chlorhexidine digluconate (CHD), bis(aminopropyl)laurylamine (BAPLA), and didecyldimethylammonium chloride (DDAC), in a hospital sewage system. Five sampling campaigns were conducted in 2016 and 2017 throughout the entire Poitiers University Hospital sewage system. DDAC concentrations ranging from 933 ± 119 to 3250 ± 482 μg/L were detected in 24-h composite samples, while lower concentrations (both within the same range) were detected for the two other compounds (i.e. 25 ± 5 to 97 ± 39 μg/L for CHD and 18 ± 3 to 142 ± 16 μg/L for BAPLA). Based on these findings, a mass balance was determined for these discharged compounds to compare the quantities detected in discharges to the amounts used for healthcare in the hospital. Hence, 60–90% of the quantities of DDAC used were found to be present at the hospital sewage outfall. Higher percentages of CHD (100–242%) were noted because of the high presumably quantities used for antiseptic applications, which were not considered in mass balance calculation. Finally, only 10–30% of BAPLA quantities used were detected at the site outfall. Analysis of the results for the different sampling points revealed the nature of the emission sources. For surface applications of DDAC and BAPLA, management of hospital linen is thus a major source of discharged biocidal products, probably following the washing of biocide-soaked textiles used for hospital facility maintenance. Moreover, discharge of biocidal products from a healthcare establishment depends especially on biocide handling practices in the emitting establishment. For BAPLA, compliance with hospital recommended dosages and practices whereby operators are required to prepare tailored quantities of detergents and disinfectants for each specific task could largely explain the limited release of this compound.
اظهر المزيد [+] اقل [-]The effect of temperature on airborne filamentous fungi in the indoor and outdoor space of a hospital النص الكامل
2019
Abbasi, Fariba | Samaei, Mohammad Reza
Fungi are one of the bioaerosols in indoor air of hospitals. They have adverse effects on staff and patients. The aim of this study was to investigate the effects of three incubation temperature on the density and composition of airborne fungi in an indoor and outdoor space of hospital. Sabouraud dextrose agar was used for culture the fungi. For improvement of aseptic properties, chloramphenicol was added to this medium. The density of airborne fungi was less than 282 CFU/m³. The highest density was detected in emergency room and the lowest of them was in neonatal intensive care unit (NICU) and operation room (OR). Results showed that fungi levels at 25 °C were higher than 37 and 15 °C (p = 0.006). In addition, ten different genera of fungi were identified in all departments. The predominant fungi were Fusarium spp., Penicillium spp., Paecilomyces spp., and Aspergillus niger. Moreover, the density and trend of distribution of Fusaruim spp. in the indoor space was directivity to outdoor space by ventilation system. The present study has provided that incubation temperature had effect on airborne fungi remarkably. We are suggested that more studies would be conducted on incubation temperature and other ambient factors on airborne fungi.
اظهر المزيد [+] اقل [-]Impacts of suspended sediment and metal pollution from mining activities on riverine fish population—a review النص الكامل
2019
Affandi, Farhana Ahmad | Ishak, Mohd Yusoff
Mining activities are responsible for the elevated input levels of suspended sediment and hazardous metals into the riverine ecosystem. These have been shown to threaten the riverine fish populations and can even lead to localized population extinction. To date, research on the effects of mining activities on fish has been focused within metal contamination and bioaccumulation and its threat to human consumption, neglecting the effects of suspended sediment. This paper reviews the effects of suspended sediment and metal pollution on riverine ecosystem and fish population by examining the possibilities of genetic changes and population extinction. In addition, possible assessments and studies of the riverine fish population are discussed to cope with the risks from mining activities and fish population declines.
اظهر المزيد [+] اقل [-]