scholarly journals The Use of Biochar of High Growth Rate Plants to Agriculturally Remediate Heavy Metal Polluted Acidic Mine Wastes

2021 ◽  
Author(s):  
Arturo Aguirre Gómez ◽  
Laura Virginia Nuñez Balderas ◽  
Claudia Hidalgo Moreno ◽  
Jorge Dionisio Etchevers Barra
Keyword(s):  
Heavy Metal ◽  
Mine Tailings ◽  
Metal Speciation ◽  
Mine Waste ◽  
Oxygen Demand ◽  
High Growth ◽  
High Growth Rate ◽  
National Standards ◽  
High Rate ◽  
Mine Wastes

The chapter is meant to expose how a sound methodology can be instrumented to both, remediate acidic metal polluted mine wastes, taking advantage of the neutralizing power and high metal sorption affinity of biochar, and to utilize pyrolyzed material derived from high-rate growth plants (water hyacinth, Eichhornia crassipes Mart, and Eucalyptus, Eucalyptus globulus Labill), which have become of ecological relevance due to their unwanted proliferation over specific terrestrial, lacustrine or riverine environments. In addition, the proposal considers not only neutralizing the mine tailings and abating the toxic levels of specific heavy metals like Pb, Cd, Cu, Zn, etc., to fulfill the international and national standards and norms, but to conveniently combine biochar with widely used soil amendments to pass widely recognized biological tests of growth using heavy metal-sensitive plants. The approach addresses firstly: a) characterizing physiochemically mine tailings and biochar, in terms of their properties (metal speciation and contents, potential acidity and neutralization potential, chemical oxygen demand, heavy metal-biochar sorption-complexing affinities, among others), and secondly; b) creating a” fertile environment” by reconditioning, agriculturally, the heavy metal-polluted acidic mine waste to allow native vegetation, or other reforesting species, to regrow on the reclaimed site, based on the bioassay tests performances.

Control of Materials and Interfaces in μc-Si:H-based Solar Cells Grown at High Rate

2011 ◽  
Vol 1321 ◽  
Author(s):  
Yasushi Sobajima ◽  
Chitose Sada ◽  
Akihisa Matsuda ◽  
Hiroaki Okamoto
Keyword(s):  
Growth Rate ◽  
Solar Cells ◽  
Film Growth ◽  
Defect Density ◽  
Density Measurement ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Bulk Region ◽  
Dangling Bond

ABSTRACTGrowth process of microcrystalline silicon (μc-Si:H) using plasma-enhanced chemicalvapor- deposition method under high-rate-growth condition has been studied for the control of optoelectronic properties in the resulting materials. We have found two important things for the spatial-defect distribution in the resulting μc-Si:H through a precise dangling-bond-density measurement, e. g., (1) dangling-bond defects are uniformly distributed in the bulk region of μc- Si:H films independent of their crystallite size and (2) large number of dangling bonds are located at the surface of μc-Si:H especially when the film is deposited at high growth rate. Starting procedure of film growth has been investigated as an important process to control the dangling-bond-defect density in the bulk region of resulting μc-Si:H through the change in the electron temperature by the presence of particulates produced at the starting period of the plasma. Deposition of Si-compress thin layer on μc-Si:H grown at high rate followed by thermal annealing has been proposed as an effective method to reduce the defect density at the surface of resulting μc-Si:H. Utilizing the starting-procedure-controlling method and the compress-layerdeposition method together with several interface-controlling methods, we have demonstrated the fabrication of high conversion-efficiency (9.27%) substrate-type (n-i-p) μc-Si:H solar cells whose intrinsic μc-Si:H layer is deposited at high growth rate of 2.3 nm/sec.

Morphological instabilities in the low pressure synthesis of diamond

1992 ◽  
Vol 7 (2) ◽  
pp. 384-393 ◽  
Author(s):  
K.V. Ravi
Keyword(s):  
Growth Rates ◽  
Diamond Films ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Diamond Growth ◽  
Diamond Crystals ◽  
Pressure Synthesis ◽  
Morphological Instabilities ◽  
The Individual

Morphological instabilities attending the high growth rate of diamond films are examined. Pertinent literature on morphological instabilities and microstructure evolution in vapor deposited films is reviewed and theoretical treatments related to the case of diamond growth are discussed. Diamond films of various thicknesses have been synthesized utilizing the combustion flame synthesis technique involving diamond growth rates of ∼1 μm/min. Films of thicknesses under 20 μm are found to be dense and the surface smoothness of such films is governed by facets on the individual crystallites that make up the film. Increasing film thicknesses, at high growth rates, results in extremely rough surfaces, the trapping of voids and discontinuities, and the incorporation of non-diamond phases in the growing film. These characteristics are typical of morphological instabilities when surface diffusion and re-evaporation processes are absent and instability is promoted by the high rate arrival of the appropriate species from the flame ambient to the surface. Factors contributing to morphological instabilities include competitive shadowing and nutrient starvation and growth anisotropy of the different crystallographic faces on individual diamond crystals. It is shown that surface temperature and the presence of oxidizing species in the flame ambient contribute to anisotropic growth of diamond crystals and hence to morphological instabilities in diamond films. An approach to avoiding these instabilities is briefly discussed.

Development of a High Rate 4H-SiC Epitaxial Growth Technique Achieving Large-Area Uniformity

2008 ◽  
Vol 600-603 ◽  
pp. 111-114 ◽  
Author(s):  
Masahiko Ito ◽  
L. Storasta ◽  
Hidekazu Tsuchida
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Free Exciton ◽  
High Growth ◽  
Maximum Growth ◽  
High Growth Rate ◽  
Maximum Growth Rate ◽  
High Rate ◽  
Intrinsic Defect ◽  
Large Area

A vertical hot-wall type epi-reactor that makes it possible to simultaneously achieve both a high rate of epitaxial growth and large-area uniformity at the same time has been developed. A maximum growth rate of 250 µm/h is achieved at 1650 °C. Thickness uniformity of 1.1 % and doping uniformity of 6.7 % for a 65 mm radius area are achieved while maintaining a high growth rate of 79 µm/h. We also succeeded in growing a 280 µm-thick epilayer with excellent surface morphology and long carrier lifetime of ~1 µs on average. The LTPL spectrum shows free exciton peaks as dominant, and few impurity-related or intrinsic defect related peaks are observed. The DLTS measurement for an epilayer grown at 80 µm/h shows low trap concentrations of 1.2×1012 cm-3 for Z1/2 center and 6.3×1011 cm-3 for EH6/7 center, respectively.

scholarly journals The danger of high growth combined with a large non-cash working capital base: A descriptive analysis

2002 ◽  
Vol 33 (1) ◽  
pp. 41-47
Author(s):  
W. Steyn ◽  
W. D. Hamman ◽  
E. V.D.M. Smit
Keyword(s):  
Growth Rate ◽  
Cash Flow ◽  
Descriptive Analysis ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Working Capital ◽  
Net Profit ◽  
A Company ◽  
Operating Activities

A high growth rate may not be the ultimate measure of a successful company. This article shows that growth at too high a rate, for a company with a high non-cash working capital component, may lead to financial difficulties.While the income statement of a company is based on the accrual of income and expenses, the cash flow statement is based on the receipt and payment of cash. A company experiencing high sales growth, depending on the extent of its non-cash working capital, will find that the cash flow from operating activities before the payment of dividends will not grow as quickly as the net profit after taxation. This is because the accrual part included in the net profit after taxation is also growing at a high rate. At such a growth rate, operating activities do not generate sufficient cash to sustain the day-to-day activities of the company.

Investigation into the microbiology of a high rate jet loop activated sludge reactor treating brewery wastewater

1996 ◽  
Vol 34 (5-6) ◽  
pp. 107-112 ◽  
Author(s):  
F. B. Dilek ◽  
G. K. Anderson ◽  
J. Bloor
Keyword(s):  
Activated Sludge ◽  
Klebsiella Oxytoca ◽  
High Growth ◽  
Basic Feature ◽  
High Growth Rate ◽  
High Rate ◽  
Klebsiella Pneumonia ◽  
Brewery Wastewater ◽  
Vibrio Fluvialis ◽  
Activated Sludge Reactor

The microbiology of a jet loop activated sludge reactor treating brewery wastewater has been investigated, with a venturi system combining liquid pumping with air diffusion being the basic feature of the system. The high F/M ratio, the high growth rate of the bacteria and the high levels of turbulence registered in the jet loop reactor caused the disappearance of filamentous bacteria and the production of a cloudy effluent. The population in the reactor was mainly formed by aerobic bacteria all belonging to the Pseudomonas species. Facultative anaerobes were present in small numbers, namely Klebsiella oxytoca, Klebsiella pneumonia ssp. pneumo., Vibrio fluvialis and Aeromonas hydrophila. Very high levels of respirometric activities were recorded for the mixed liquor of the reactor. The respirometric activities of individual isolates were also found to be remarkably high, especially when treating brewery wastewater. The magnitudes of their activities were a function of their relative abundance within the reactor.

Migration and speciation of heavy metal in salinized mine tailings affected by iron mining

2017 ◽  
Vol 76 (7) ◽  
pp. 1867-1874 ◽  
Author(s):  
Xu Zhang ◽  
Huanhuan Yang ◽  
Zhaojie Cui
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Mine Tailings ◽  
Metal Speciation ◽  
Transformation Process ◽  
Laboratory Research ◽  
Human Beings ◽  
Negative Effects ◽  
Field Investigations ◽  
Close Relationship

The negative effects of heavy metals have aroused much attention due to their high toxicity to human beings. Migration and transformation trend of heavy metals have a close relationship with soil safety. Researching on migration and transformation of heavy metals in tailings can provide a reliable basis for pollution management and ecosystem restoration. Heavy metal speciation plays an important role in risk assessment. We chose Anshan tailings for our study, including field investigations and laboratory research. Four typical heavy metal elements of mine tailings {Fe (373.89 g/kg), Mn (2,303.80 mg/kg), Pb (40.99 mg/kg) and Cr (199.92 mg/kg)} were studied via Tessier test in vertical and horizontal direction. The main speciation of heavy metals in Anshan tailings was the residual. However, heavy metals have a strong ability for migration and transformation in vertical and horizontal directions. Its tendency to change from stable to unstable speciation results in increasing bioavailability and potential bioavailability. Fe, Mn, Pb and Cr showed different ability in the migration and transformation process (Mn > Pb > Fe > Cr) depending on the characteristics of heavy metals and physicochemical properties of the environment.

Experimental Study on the Solidification/Stabilization of Textile Dyeing Sludge

2011 ◽  
Vol 197-198 ◽  
pp. 1010-1015
Author(s):  
Xun An Ning ◽  
Jian Bo Zhou ◽  
Jing Yong Liu ◽  
Zuo Yi Yang ◽  
Yu Tian ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Compressive Strength ◽  
Oxygen Demand ◽  
Heavy Metal Concentration ◽  
National Standards ◽  
Curing Time ◽  
Optimum Conditions ◽  
Heavy Metal Concentrations ◽  
Textile Dyeing ◽  
Compressive Strength Test

Sludge from the textile dyeing industries was solidified and stabilized using cement, fly ash（PFA）and cinder as the solidifying agents, and the optimum conditions of sludge solidification/stabilization were analyzed. The mechanical property of solidified sludge block was evaluated by compressive strength test, at the same time， the chemical oxygen demand (COD） and heavy metal concentration of the leaching from the cured block were tested as well. With the dosage of cement, PFA and cinder, 0.15kg/kg, 0.02kg/kg and 0.08kg/kg respectively, and curing time was 6ds, the compressive strength of the solidified sludge block reached 330kPa.Results showed that addition of cement and cinder had good effects on the compressed strength of sludge block, cement, PFA and cinder enhanced the solidification and stabilization of organic and heavy metal in the sludge. Under the above conditions, COD of the leaching from the sludge solidification block was 488mg/L, and the heavy metal concentrations had reached the related national standards. After 6ds of curing time, water ratio of the solidified block was maintained at 40%~45%, which met the prescribed standards of landfill.

Experimental Study on New Technology for Solidifying/Stabilizing Papermaking Sludge

2010 ◽  
Vol 156-157 ◽  
pp. 84-89
Author(s):  
Xu Nan Ning ◽  
Shi Wen Li ◽  
Jing Yong Liu ◽  
Zuo Yi Yang ◽  
Zhu Ying
Keyword(s):  
Mechanical Properties ◽  
Heavy Metals ◽  
Heavy Metal ◽  
Compressive Strength ◽  
New Technology ◽  
Oxygen Demand ◽  
Heavy Metal Concentration ◽  
National Standards ◽  
Curing Time ◽  
Water Ratio

For better harmlessly treatment of papermaking sludge, a new technology for solidifying and stabling of sludge was studied. Papermaking sludge was solidified and stabilized by the solidifying agents including cement, powder fly ash (PFA) and cinder. The mechanical properties of solidified sludge block were evaluated by compressive strength, chemical oxygen demand (COD) and heavy metals concentration in the leachate from the solidified block were tested as well. When the solidifying agents has the following composition (cement 0.12kg/kg, PFA 0.02kg/kg and cinder 0.10kg/kg respectively), and the curing time was 6ds, the compressive strength of the solidified sludge blocks reached 360kPa. The results showed that cement and cinder were all positive in the compressed strength of sludge block. If they were mixed with PFA together, they could enhanced the solidification of organic and heavy metals in the sludge. Under this conditions, the COD in leachate from the solidified block was 115.7 mg/L, and the heavy metal concentration had reached the related national standards, after 6ds of curing time, water ratio of the solidified block kept from 35% to 40%, which met the prescribed standards of landfill.

scholarly journals Options for Financing the Budgetary Deficit, Money Supply, and Growth of Banking Sector

1991 ◽  
Vol 30 (4II) ◽  
pp. 769-784
Author(s):  
A. R. Kemal
Keyword(s):  
Money Supply ◽  
Banking Sector ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Price Stability ◽  
Fiscal Deficit ◽  
Monetary Expansion ◽  
Rate Structure ◽  
The Impact

The fiscal deficit has assumed alarming proportions in Pakistan; it was as large as 8.5 percent of the GDP in 1987-88. Though it has fallen somewhat in recent years, yet it still is around 6.7 percent of GDP. While the fiscal deficit was expected to result in a high rate of inflation and slow growth of output, Pakistan has sustained a high growth rate of output with price stability. This makes Pakistan a fascinating case study.l The impact of the fiscal deficit on monetary expansion, growth of output and price stability in various countries has been extensively analysed. For example, see Cline (1987); Collins and Park (1989), Corbo (1985,1989); Corbo and de Melo (1989); Corbo and Nam (1988); Dornbusch and de Pablo (1989); Easterly (1989); Edwards (1989); Enders and Mattione (1984); Gil Diaz (1988); Haque (1987); Kim and Yun (1988); Kormendi (1983); Modigliani and Sterling (1986); Nash (1988); Ocampo (1987); Reisen and van Trotsenburg (1988); van Wijnbergen (1987) and Yellen (1989). However, very little work is available on Pakistan. The present study is an attempt to fill that important gap. By analysing trends in the budgetary deficit and in the pattern of financing the deficit, the present study explores their implications for the interest rate structure, monetary expansion, and growth of the banking sector in Pakistan. The paper is divided into four sections. Section I traces the trends in the fiscal deficit over time. Patterns of financing the deficit and implications for monetary expansion are analysed in Section II. Section III examines the implications of changes in the rate structure of interest for the growth of money supply and the banking sector. Section IV presents the main conclusions of the study.

High-Rate Growth of Stable a-Si:H

1999 ◽  
Vol 557 ◽  
Author(s):  
T. Takagi ◽  
R. Hayashi ◽  
A. Payne ◽  
W. Futako ◽  
T. Nishimoto ◽  
...  
Keyword(s):  
Vapour Deposition ◽  
Film Growth ◽  
Density Ratio ◽  
Excitation Frequency ◽  
Chemical Vapour ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Hydrogenated Amorphous ◽  
Silane Plasma

AbstractCorrelation between the gas phase species in silane plasma measured by mass spectrometry and the properties of hydrogenated amorphous silicon (a-Si:H) films deposited by plasma enhanced chemical vapour deposition (PECVD) has been investigated. We have especially been interested in the higher-order silane related species in the plasma, whose contribution to the film growth is considered to be the cause of light-induced degradation in the film quality, especially at high growth rate. In this study, we varied excitation frequency, gas pressure and power density to vary the growth rates of a-Si:H films ranging from 2 Å/s to 20 Å/s.Molecular density ratio of trisilane, representative of higher silane related radicals, to monosilane has shown a clear correspondence to the fill factor after light soaking of Schottky cells fabricated on the resulting films.

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