摘要 :
Anodizing wastewater contains principally phosphate (PO_4~(3-) ) anions according to previous studies, but with the purpose to promote water reuse in this type of industry, a complete characterization of wastewater was made to rem...
展开
Anodizing wastewater contains principally phosphate (PO_4~(3-) ) anions according to previous studies, but with the purpose to promote water reuse in this type of industry, a complete characterization of wastewater was made to remove other anions and cations also present in significant concentration. Particularly, the adsorption of sodium (Na~+), potassium (K~+), fluoride (F~-), sulfate (SO_4~(2-)) and phosphate (PO_4~(3-)) was studied using different sorbents such as: coconut shell activated carbon, bone char, bituminous coal activated carbon, natural zeolite, silica, anionic and cationic exchange resins, a coated manganese-calcium zeolite, coconut shell activated carbon containing iron and iron hydroxide. All sorbents were characterized using FT-IR spectroscopy, potentiometric titration, nitrogen adsorption isotherms at 77 K, X-ray diffraction and SEM/EDX analysis to study the adsorption mechanism. The adsorption studies were performed in batch systems under constant agitation using both standard solutions of each ion and real anodizing wastewater. Results showed that, in general, the adsorption of all anions and cations is higher when mono-component standard solutions were used, since in the anodizing wastewater all species are competing for the active sites of the adsorbent. Na~+ present in anodizing wastewater was efficiently adsorbed on coated manganese-calcium zeolite (20.55 mg/g) and natural zeolite (18.55 mg/g); while K~+ was poorly adsorbed on all sorbents (less than 0.20 mg/g). Anions such as F~-, SO_4~(2-) and PO_4~(3-), were better adsorbed on the anionic resin (0.17, 45.38 and 2.92 mg/g, respectively), the iron hydroxide (0.14, 7.95 and 2.87 mg/g, respectively) and the bone char (0.34, 8.71 and 0.27 mg/g, respectively). All these results suggest that adsorption is a promising tertiary treatment method to achieve water reuse in the anodizing industry.
收起
摘要 :
Pistachia lentiscus (LPw) and date palm leaves (PDw) are two biosorbents that are mainly used for the removal of chromium and cobalt from an aqueous solution. These biosorbents were characterized by physicochemical procedures, inc...
展开
Pistachia lentiscus (LPw) and date palm leaves (PDw) are two biosorbents that are mainly used for the removal of chromium and cobalt from an aqueous solution. These biosorbents were characterized by physicochemical procedures, including Fourier transform infrared spectroscopy, zero charge point, Boehm method, and Brunauer-Emmett-Teller (BET) method. Various parameters, such as contact time, biosorbent quantities, diameter of the biosorbent particles, ionic strength, initial pH, and initial concentration of solutions, were optimized. The reactions of PDw+Co, LP+Co, and LPw+Cr exhibited similar isotherm profiles of type L, but indicated isotherm type C in the reaction PDw+Cr profile, according to the BET classification. All reactions mentioned above were described by the Freundlich and Temkin adsorption isotherm models, with R~2 greater than 0.97. The kinetics most likely followed the pseudo-second-order model which was confirmed by error calculation.
收起
摘要 :
Introduction. At home suture or staple removal can be stressful for patients and may lead some to seek out additional instruction via online resources as an adjunct to what was explained to them by their provider. The purpose of t...
展开
Introduction. At home suture or staple removal can be stressful for patients and may lead some to seek out additional instruction via online resources as an adjunct to what was explained to them by their provider. The purpose of this study was to examine the existing online resources available to patients who may be interested in or have been instructed to remove sutures at home after a simple procedure such as a skin biopsy or excision. Methods. ?A systematic search was conducted using internet search engines to identify videos and webpages targeting at home suture removal instruction. The DISCERN instrument was used to evaluate the information quality of each included resource. Results. ?There was no statistically significant difference between average DISCERN scores for videos and webpage resources, and the majority were rated poor in quality. Conclusions. ?The online resources for at home suture and staple removal are often not comprehensive and are below the standard quality for written information. Healthcare providers should consider referring their patients to validated online sources for suture removal to prevent misinformation and improve patient safety.
收起
摘要 :
The development of an adsorbent system and process conditions for the removal of sulfur-compounds from natural gas at ambient conditions of temperature and pressure to meet the purity specifications required for use in the fuel pr...
展开
The development of an adsorbent system and process conditions for the removal of sulfur-compounds from natural gas at ambient conditions of temperature and pressure to meet the purity specifications required for use in the fuel processor of a PEM fuel cell is described. The sulfur compounds to be removed from the natural gas were H2S, dimethyl sulfide (DMS), carbonyl sulfide (COS), ethyl mercaptan (EM) and tertiary butyl mercaptan (TBM). The water content of natural gas was 120 ppmw. Metal-exchanged zeolites (Ca-X and Na-X) and mixed metal oxides (of Cu-Mn and Fe-Mn) supported on alumina were used as adsorbents. Even though some of the adsorbents were active for the removal of particular sulfur compounds (Ca-X, for example, for the removal of DMS), none of them could remove all the sulfur impurities simultaneously. Multiple adsorbents are necessary. The choice of the combination of adsorbents depends on the type and relative amounts of the various sulfur compounds. The latter vary with the origin and source of the natural gas feedstock. The sequential location and quantity of the individual adsorbents in the total adsorbent bed is also a critical parameter. A sequential bed system comprising of Ca-X followed by Fe-Mn oxides had significant desulfurization capacity at 38 °C, 15 psig, and a natural gas space velocity of 6000 h~(-1). This combination of adsorbents was also tolerant to the presence of water, aromatics, CO2, higher hydrocarbons and other such impurities sometimes present in the pipeline natural gas.
收起
摘要 :
The paper presents a clutter detection and removal algorithm for complex document images. This distance transform based technique aims to remove irregular and independent unwanted clutter while preserving the text content. The nov...
展开
The paper presents a clutter detection and removal algorithm for complex document images. This distance transform based technique aims to remove irregular and independent unwanted clutter while preserving the text content. The novelty of this approach is in its approximation to the clutter–content boundary when the clutter is attached to the content in irregular ways. As an intermediate step, a residual image is created, which forms the basis for clutter detection and removal. Clutter detection and removal are independent of clutter’s position, size, shape, and connectivity with text. The method is tested on a collection of highly degraded and noisy, machine-printed and handwritten Arabic and English documents, and results show pixel-level accuracies of 99.18 and 98.67 % for clutter detection and removal, respectively. This approach is also extended to documents having a mix of clutter and salt-and-pepper noise.
收起
摘要 :
The paper presents a clutter detection and removal algorithm for complex document images. This distance transform based technique aims to remove irregular and independent unwanted clutter while preserving the text content. The nov...
展开
The paper presents a clutter detection and removal algorithm for complex document images. This distance transform based technique aims to remove irregular and independent unwanted clutter while preserving the text content. The novelty of this approach is in its approximation to the clutter-content boundary when the clutter is attached to the content in irregular ways. As an intermediate step, a residual image is created, which forms the basis for clutter detection and removal. Clutter detection and removal are independent of clutter's position, size, shape, and connectivity with text. The method is tested on a collection of highly degraded and noisy, machine-printed and handwritten Arabic and English documents, and results show pixel-level accuracies of 99.18 and 98.67 % for clutter detection and removal, respectively. This approach is also extended to documents having a mix of clutter and salt-and-pepper noise.
收起
摘要 :
Purpose The performances of filter systems that use earthworms and plants, combined with earthworm eco-filter (EE) systems in treating synthetic domestic sewage (SDS) with different C/N ratios, were investigated for a 9-month peri...
展开
Purpose The performances of filter systems that use earthworms and plants, combined with earthworm eco-filter (EE) systems in treating synthetic domestic sewage (SDS) with different C/N ratios, were investigated for a 9-month period. Methods The effects of the combination of filters, earthworms, plants, as well as the combination of earthworms and plants on SDS nutrient removal efficiency were separately investigated to select the optimum system for treating SDS. The results of the current study could be used to determine how treatment performance responds to different C/N ratios and to explain and predict the performance of an operating EE system.Results EE systems with earthworms and plants (EP groups) consistently performed better than the other types of systems (CK, E, and P; that is, without earthworms and without plants, with earthworms and without plants, and without earthworms and with plants, respectively) under all C/N ratios. The highest removal efficiencies of chemical oxygen demand, total nitrogen, total phosphorus, and total organic carbon were achieved under C/N ratios of 6:1, 6:1, 6:1, and 9:1, respectively. The optimum nutrient removal efficiency was achieved at C/N=6, and the contribution order for nutrient removal was EP > P > E > CK. Conclusions Influent C/N ratios, the time of year, and the synergetic effects of earthworm behavior and microorganisms significantly affected nutrient removal efficiencies. Considering the removal of all nutrients, EE systems with plants and earthworms achieved optimum removal effects in July when the influent C/N ratio was controlled at 6. Appropriate control of carbon and nitrogen source concentrations permitted the achievement of optimal nutrient removal effects.
收起
摘要 :
Biogas is an environment-friendly fuel but that must be upgraded before being utilized. The method about removing CO_2 from biogas by microalgal culturing using biogas effluent as nutrient medium in this study could effectively up...
展开
Biogas is an environment-friendly fuel but that must be upgraded before being utilized. The method about removing CO_2 from biogas by microalgal culturing using biogas effluent as nutrient medium in this study could effectively upgrade biogas and simultaneously reduce the biogas effluent nutrient. Results showed that the optimum parameters for microalgal growth and biogas effluent nutrient reduction was moderate light intensity with middle photoperiod. While low light intensity with long photoperiod and moderate light intensity with middle photoperiod obtained the best biogas CO_2 removal and biogas upgrade effects. Therefore, the optimal parameters were moderate light intensity 350μmolm~(-2)s~(-1) with middle photoperiod 14h light:10h dark. Under this condition, the microalgal dry weight, CH_4 concentration, reduction efficiency of chemical oxygen demand, total nitrogen, and total phosphorus was 615.84±33.07mgL~(-1), 92.16±2.83% (v/v), 88.74±3.45%, 83.94±3.51%, and 80.43±4.17%, respectively.
收起
摘要 :
In Japan, nearly 30 percent of piggery farms installed wastewater treatment facilities. Most of the facilities adopt aerobic treatment system based on the activated sludge process. This process is reliable and has high performance...
展开
In Japan, nearly 30 percent of piggery farms installed wastewater treatment facilities. Most of the facilities adopt aerobic treatment system based on the activated sludge process. This process is reliable and has high performance of organic pollutant removal. However, running cost reduction and implementation of advanced treatment process for removing phosphorus, nitrogen and color become more and more important for farmers due to embarrassed economy and strengthen of environmental legislation on effluent water quality. Thus, development of new treatment process has become important task, which process has performance of phosphorus, nitrogen and color removal with low running cost. Though this task is difficult to accomplish, several new fundamental processes have been investigated which are anticipated a contribution to the improvement of the treatment systems.
收起
摘要 :
The purpose of this study was to investigate the influence of increasing sulfate concentrations on chromium removal, to evaluate the effect of the presence of Cr(VI) on sulfate removal by Streptomyces sp. MC1 and to analyze the di...
展开
The purpose of this study was to investigate the influence of increasing sulfate concentrations on chromium removal, to evaluate the effect of the presence of Cr(VI) on sulfate removal by Streptomyces sp. MC1 and to analyze the differential protein expression profile in the presence of this metal for the identification of proteins repressed or overexpressed. In the presence of Cr(VI) but in the absence of sulfate ions, bacterial growth was negligible, showing the Cr(VI) toxicity for this bacterium. However, the sulfate presence stimulated bacterium growth and Cr(VI) removal, regardless of its concentrations. Streptomyces sp. MC1 showed ability to remove chromium and sulfate simultaneously. Also, the sulfate presence favored the decrease of total chromium concentration from supernatants reaching a decrease of 50% at 48h. In presence of chromium, seven proteins were down-expressed and showed homology to proteins involved in protein biosynthesis, energy production and free radicals detoxification while two proteins involved in oxidation-reduction processes identified as dihydrolipoamide dehydrogenase and S-adenosyl-l-methionine synthase were overexpressed.
收起
原文获取