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Resultados 1651-1660 de 3,243
Adsorption Characteristics of Lead (Pb2+) and Cadmium (Cd2+) by an Isolated Bacterium from Soil Samples Obtained from a Tungsten Mine
2015
Ming Chen | Qingyun Cai | Jinxia Nie | Qinghua Zeng
Eight bacterial strains were isolated from lead-cadmium contaminated soil samples obtained from a Tungsten mine. Pb2+ and Cd2+ adsorption abilities of the isolated strains were screened. One isolate, referred to as Strains S, was selected for further study because of its relatively high adsorption ability. Five factors affecting adsorption of Pb2+ and Cd2+ were studied, namely, the initial concentration of Pb2+ or Cd2+, temperature, pH, biomass of Strains S, and adsorption time. Results indicated that Strains S best adsorbed Pb2+ when the initial concentration of Pb2+ was 100 mg/L, temperature was 35°C, pH was 6.5, dosage was 0.1 g, and adsorption time was 20 min. In contrast, Strain S best adsorbed Cd2+ at an initial Cd2+ concentration of 100 mg/L, temperature of 40°C, pH 6.5, dosage of 0.1 g, and adsorption time of 20 min. The experimental data were fitted to the Langmuir and Freundlich adsorption isotherm models, and the results indicated that the Langmuir model better fitted the experimental data. The results of infrared spectroscopy revealed that the functional groups involved in adsorption of Cd2+ and Pb2+ were -OH, -NH2, -S=O and -P=O. Using 16S rDNA sequencing and phenotypic properties test, Strains S was identified as Enterobacter sp.
Mostrar más [+] Menos [-]Effect of Salinity and Photoperiod on Growth of Microalgae Nannochloropsis sp. and Tetraselmis sp.
2015
Fakhri M. | Arifin N. B. | Budianto B. | Yuniarti A. | Hariati A. M.
In this present study, the effect of salinity and photoperiod on the growth of Nannochloropsis sp. and Tetraselmis sp. was examined to optimize microalgal growth. Different salinities (5, 10, 15 and 20‰) for Nannochloropsis sp. and (10, 15, 20 and 25‰) for Tetraselmis sp. were studied. Both microalgae were cultivated at two different photoperiod cycles (24:0 and 12:12 h light:dark). Maximum growth rates and cell concentrations for Nannochloropsis sp. and for Tetraselmis sp. were achieved at salinities of 10 and 15‰, respectively. In terms of photoperiod, the maximum growth rates and cell concentrations for both microalgae were obtained at photoperiod of 24:0 h light:dark. This study shows that the cell concentrations and growth rates of both microalgae are highly dependent on salinity and photoperiod.
Mostrar más [+] Menos [-]Study of Material Flow Analysis of Paper Waste in Municipal Solid Waste of Lahore Cantonment
2015
Fatima Syeda Amber | Ilyas Fizza
This research study explains the material flow of paper from households to containers and ultimately to landfills. Moreover, it shows different behavior of various households towards the consumption of different paper products and the way they reuse them. Sampling was carried out from households, kerbside containers and landfills where material flow of paper was studied. Percentage composition was calculated on different waste items including paper. Six major paper items were segregated namely glossy paper, cardboard, tissue paper, boxboard, office paper and newspaper. Moreover, proximate analysis was carried out to find out the values for fixed carbon, ash content, moisture content and volatile organic compounds (VOC’s) for different paper items mentioned above. Material flow of paper from households to kerbside containers and then to landfills was observed. The results showed that waste paper from the households is of very fine quality and before reaching to the landfill site it is either sold, reused or recovered. Today in Pakistan, the act of recovering paper from the waste stream is carried out by the informal sector which if followed by the formal sector too can raise profits and economic development.
Mostrar más [+] Menos [-]Calculation and Estimation of the Carbon Footprint of Paint Industry
2015
Saif Samia | Feroz Anum | Khan M. Asif | Akhtar Sana | Mehmood Asim
The world’s climate is changing rapidly, and these changes are having detrimental impacts on human health and the environment. Major part of it is contributed by the anthropogenic activities. The current study is undertaken for the estimation and calculation of the carbon footprint of the paint industry. In order to find out the greenhouse gas emissions released by the industry, the carbon footprint of the industry was calculated following the greenhouse gas (GHG’s) protocol guidelines. The study includes emissions from different sources. Scope 1 emissions account for the direct emissions, these include emissions from industry owned boilers, generators, furnaces and vehicles. The Scope 2 emissions account for the indirect emissions, emitted from purchased electricity and natural gas generation. And Scope 3 emissions include emissions generated from waste disposal and employee business travel. The highest amount of emissions was released from Scope 1 which was 714 tCO2e followed by Scope 2 emissions which were calculated to be 703.011 tCO2e and then Scope 3 emissions which were 105.733 tCO2e. The total carbon footprint calculated for the industry was 2105.733 tCO2e.
Mostrar más [+] Menos [-]Comparative Study of Performance Evaluation of UASB Reactor for Treating Synthetic Dairy Effluent at Psychrophilic and Mesophilic Temperatures
2015
Sivakumar R. | Sekaran V.
Dairy industry contributes to the pollution of the environment, both in quality and quantity. It generates about 0.2 to 10 L of effluent per liter of milk processed. Up-flow anaerobic sludge blanket is most suitable for biodegradable wastes, hence the present study evaluated the performance of UASBR through a laboratory model (25 liters of volume) for treating the dairy effluent with maintained psychrophilic temperature (15-20ºC) at phase I and mesophilic temperature (30-40ºC) at phase II. This model was studied for its treatment efficiency in terms of COD reduction. In the phase I, the average varying influent COD applied over the model are 1684, 2693, 3160, 3637, and 4059 mg/L with flow rates for each average influent COD as 4.80, 9.60, 14.40, 19.20 and 24.00 L/d. It was found that, successful COD removal of 91.42% was for the operating conditions of OLR at 0.039 kg COD/kg VSS day, VLR at 0.70 kg COD/m3 day and HRT at 5.21 days. In the phase II the average varying influent COD of 2316, 2827, 3329, 3908 and 4522 mg/L were applied with same flow rates. The experimental work on UASBR model was found successful with 94.70% COD removal under the operating conditions of OLR at 0.037 kg COD/kg VSS day, VLR at 0.630 kg COD/m3day and HRT at 5.21 days. The reactor achieved BOD, TSS, TDS, N and P removal efficiency, observed in phase I and II, as 91%, 82%, 89%, 42% and 46% and 96.4%, 86%, 91%, 41% and 50% respectively.
Mostrar más [+] Menos [-]Application of Regression Analytical Method in Dynamic Prediction of River Water Quality
2015
Pan Jianbo | Zhou Gao | Liu Dedong
It is very important to accurately predict the river water quality. Prediction of river water quality has been closely watched in water resources evaluation, and is the primary work of scientific planning and management of water resources and exploitation. The accuracy of prediction will directly influence whether we can work out a reasonable plan and management measures. According to the relationship of river water quality with the influencing factors, regression method is used to predict the tendency of river water quality. The influencing factors include rainfall, sediment and runoff. This study could provide reference and guidance for further exploitation of river water.
Mostrar más [+] Menos [-]Spatial Pattern and Environmental Quality Assessment of Potentially Toxic Elements in Soils of Central Agricultural Areas, China
2015
Yang Chunlin | Guo Ruiping
Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, and Zn concentrations in surface soils of central agricultural areas were investigated to evaluate the environmental quality of these potentially toxic elements using 603 samples. The following average concentrations were obtained: Cu, 21.8 mg/kg | Ni, 28.4 mg/kg | Cr, 74.0mg/kg | Co, 13.2 mg/kg | Mn, 677.1 mg/kg | Pb, 28.2 mg/kg | Hg, 0.047 mg/kg | Cd, 0.194 mg/kg | Zn, 63.7 mg/kg. Correlation analysis was applied to evaluate the results and identifying the possible sources of these potentially toxic elements. Distribution maps of the elements were created using the inverse distance weighted interpolation method. The nine metals exhibited generally distinct geographical patterns. Results showed that 6,730 km2 of the study area presented higher pollution indices and was slightly polluted.
Mostrar más [+] Menos [-]Managing Multi-functional Forests Using Forest Development types (FDTs) - A Perspective from Monoculture Forests in Southern Subtropical China
2015
Pang Lifeng | Jiang Jun | Lu Yuanchang
The Chinese Government wants to develop mixed stands with complex structures, particularly in monoculture forest areas. However, despite the enthusiasm for planting trees, is sufficient thought being given to the development of forestry objectives? A logical alternative would seem to describe the structure of such mixed stands through the use of specific-model management tools. This paper conceptualizes and assesses forest development types (FDTs) of management designs and silvicultural principles across three contemporary forest development types: the restoration, the nature-based, and the commercial paradigms. Forest development type design and silvicultural treatments were conceptualized from a review and case studies. The study was conducted as a case study focusing on the planning and development of long-term management goals for three mixed stands for multiple uses. Using FDTs, visual representations of planting design and stand development were obtained as a basis for the “expert” assessment of five criteria: the forest overview, the objectives, the proportion of tree species, the mix type, and the management operations. The assessment showed that forests vary considerably among planting designs and silvicultural systems. FDTs utilizing succession and variation in species, diversity, growth and tree regeneration offer an extended paradigm of multi-functional management. With regard to the ongoing move from timber-dominated forestry to the multifunctional management of mixed stands, fostering dialogue may be the most effective means for forest development types to contribute to the implementation of new management paradigms.
Mostrar más [+] Menos [-]Effect of Forest Composition and Dynamics of Light on Seedlings and Saplings of Korean pine (Pinus koraiensis) in Northeastern China
2015
Yang Junlong | Zhang Guochun | Liu Wenhui | Liu Qijing
Natural regeneration of Korean pine (Pinus koraiensis Siebold & Zucc.) in northeastern China has often been problematic in mixed broad-leaved Korean pine forests (primary forest), but not in deciduous broad-leaved forests (secondary forest). Light transmittance, soil temperature, leaf area index (LAI), height and diameter of Korean pines were estimated in order to examine the contribution of composition and the dynamics of light to Korean pine regeneration in two forests. A spatial point pattern analysis was carried out to investigate the response of seedlings and saplings to light regimes and their relationship with mature trees, graded by size. We draw the following results: (1) light conditions were better in the secondary forest than in the primary forest in late spring (June and July) before the leaf expansion and the secondary forest received more light before leaf expansion and less light penetration in the early summer (August) | (2) our spatial analysis indicated that seedlings are negatively correlated with saplings and exhibit a higher degree of clumping than saplings. Relationships of seedlings with mature pines and all sizes of other mature trees appeared random, whereas saplings were negatively associated with small, medium and large mature trees. Our findings suggest that the effect of forest composition on regeneration mainly occurred before the leaf expansion in late spring.
Mostrar más [+] Menos [-]A Model for Assessing Water Purification Capacity of Algae to Eutrophication at Large-Scale
2015
Wei-zhuo Wang | Jian-min Bian | Wenxi Lu
It has been observed that water in the reservoirs has a trend towards eutrophication even under natural environment, while human activity makes the situation worse. Studies on eutrophication are mainly focused on nutritive salt control. It is an effective method to remove the nutrient substance by using attached algae | however, due to experimental limitations, the theoretical results from the lab study are commonly inapplicable to the natural environment. In this paper, based on a case study on the Hada reservoir, we have built a hydrodynamic-quality model that represents the current state of the reservoir. With the help of the model, we can verify the development of eutrophication of the reservoir and simulate the spatial-temporal evolvement, using Cladophora, to deal with eutrophication within a shallow water reservoir.
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