Mo-Si-B系原位复合材料的研究

Mo-Si-B系原位复合材料是一族新型的高温结构材料,目前的研究主要集中在其中的α-Mo Mo3Si Mo 5SiB2(T2)、Mo 5Si3Bx(T1) Mo3Si Mo5SiB2(T2)和Mo5Si3Bx(T1) MoSi2 MoB 3个体系.详细介绍了Mo-Si-B系原位复合材料的研究进展及应用前景,并在此基础上提出了进一步研究的重点和方向.     

Removal of a dye from simulated wastewater by adsorption using treated parthenium biomass

In the present study adsorption of rhodamine-B from aqueous solution on formaldehyde treated parthenium biomass (WC) and phosphoric acid treated parthenium carbon (PWC) was studied. Aqueous solutions of various concentrations (50-500 mg/l) were shaken with certain amount of adsorbent to determine the adsorption capacity of rhodamine-B on WC and PWC. The effectiveness of formaldehyde treated parthenium biomass (WC) and phosphoric acid treated parthenium carbon (PWC) in adsorbing rhodamine-B from aqueous solution has been studied as a function of agitation time, adsorbent dose, initial dye concentration and pH. The adsorption capacities of the studied adsorbents were in the order PWC>WC. Initial pH had negligible effect on the adsorption capacity. Maximum dye was sequestered from the solution within 60min after the start of every experiment. After that, the concentration of rhodamine-B in the liquid-phase remained constant. The adsorption of rhodamine-B onto PWC and WC followed second-order kinetic model. Adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity Q(0) was 59.17 mg/g at initial pH 7.0 for the particle size 0.3-1.0mm for phosphoric acid treated parthenium carbon (PWC). The FT-IR spectra of the adsorbents were recorded to explore number and position of functional groups available for the binding of dye cation onto studied adsorbents. SEMs of the adsorbents were recorded to explore the morphology of the studied adsorbents.     

Dye wastewater treated by Fenton process with ferrous ions electrolytically generated from iron-containing sludge

Fenton process was employed to treat synthetic dye wastewater with supply of Fe(II) electrolytically generated from iron-containing sludge which was recycled and reused throughout the study. Treated water quality and properties of iron sludge after being repeatedly used were reported and discussed. Experimental results showed that COD was mainly removed by oxidation other than coagulation. Although, the process was quite effective for COD and color removal, conductivity of treated water was enormously high. Meanwhile, repeated use of iron-containing sludge results in accumulation of organic materials embedded in the sludge as indicated by increasing volatile suspended solid (VSS)/TSS ratio and decreasing zeta potential.     

Improvement of COD and color removal from UASB treated poultry manure wastewater using Fenton's oxidation

The applicability of Fenton's oxidation as an advanced treatment for chemical oxygen demand (COD) and color removal from anaerobically treated poultry manure wastewater was investigated. The raw poultry manure wastewater, having a pH of 7.30 (+/-0.2) and a total COD of 12,100 (+/-910) mg/L was first treated in a 15.7 L of pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB reactor was operated for 72 days at mesophilic conditions (32+/-2 degrees C) in a temperature-controlled environment with three different hydraulic retention times (HRT) of 15.7, 12 and 8.0 days, and with organic loading rates (OLR) between 0.650 and 1.783 kg COD/(m3day). Under 8.0 days of HRT, the UASB process showed a remarkable performance on total COD removal with a treatment efficiency of 90.7% at the day of 63. The anaerobically treated poultry manure wastewater was further treated by Fenton's oxidation process using Fe2+ and H2O2 solutions. Batch tests were conducted on the UASB effluent samples to determine the optimum operating conditions including initial pH, effects of H2O2 and Fe2+ dosages, and the ratio of H2O2/Fe2+. Preliminary tests conducted with the dosages of 100 mg Fe2+/L and 200 mg H2O2/L showed that optimal initial pH was 3.0 for both COD and color removal from the UASB effluent. On the basis of preliminary test results, effects of increasing dosages of Fe2+ and H2O2 were investigated. Under the condition of 400 mg Fe2+/L and 200 mg H2O2/L, removal efficiencies of residual COD and color were 88.7% and 80.9%, respectively. Under the subsequent condition of 100 mg Fe2+/L and 1200 mg H2O2/L, 95% of residual COD and 95.7% of residual color were removed from the UASB effluent. Results of this experimental study obviously indicated that nearly 99.3% of COD of raw poultry manure wastewater could be effectively removed by a UASB process followed by Fenton's oxidation technology used as a post-treatment unit.     

Fixed bed column study for Cd(II) removal from wastewater using treated rice husk

A fixed bed of sodium carbonate treated rice husk was used for the removal of Cd(II) from water environment. The material as adopted was found to be an efficient media for the removal of Cd(II) in continuous mode using fixed bed column. The column having a diameter of 2 cm, with different bed depths such as 10, 20 and 30 cm could treat 2.96, 5.70 and 8.55 l of Cd(II) bearing wastewater with Cd(II) concentration 10 mg/l and flow rate 9.5 ml/min. Different column design parameters like depth of exchange zone, adsorption rate, adsorption capacity, etc. was calculated. Effect of flow rate and initial concentration was studied. Theoretical breakthrough curve was drawn from the batch isotherm data and it was compared with experimental breakthrough curve. An amount of 0.01 mol/l HCl solution was used for desorption of adsorption column. Column regeneration and reuse studies were conducted for two cycles of adsorption-desorption.     

Optimization of the aerobic biological treatment of thermophilically treated refractory wastewater

A pilot scale conventional activated sludge was operated for over 600 days to study its effectiveness at further remediating the effluent of an existing industrial site's thermophilic biological treatment stage. During the course of the study, the activated sludge was able to further biodegrade the contaminants in the incoming industrial wastewater in terms of both BOD and nitrogen reductions at varying hydraulic and solids retention times, despite elevated concentrations of soluble copper being present. A limiting hydraulic retention time (HRT) for BOD removal of 1.5 days was observed as well as the loss of nitrification occurred at a solids retention time (SRT) of approximately 6 days. Biokinetic coefficients were determined with the maximum rate of substrate utilization per unit mass of microorganisms, k, of 0.14 mgVSS/(mgsBOD-d) and the Monod half velocity constant, K(s), of 9.4 mgsBOD/L. Simultaneous nitrification and denitrification (SND) of the nitrogenous compounds found in this wastewater was observed throughout the majority of the experimentation while the bulk DO in the system was greater than 1 mg/L. The activated sludge was estimated to contain soluble copper on the order of 1 mg/L throughout the course of operation with no apparent detriment to nitrification. Additionally, the activated sludge was able to biologically remove the main solvents found in the influent wastewater. The removals of trace levels of N-nitrosodimethylamine (NDMA) were also observed.     

Reduction of organic matter and trihalomethane formation potential in reclaimed water from treated industrial estate wastewater by coagulation

Raw water from treated industrial estate wastewater in northern Thailand was used in jar-test coagulation experiments with variations of separate alum and ferric chloride dosages from 10 to 80 mg/L at pH conditions ranging from 5 to 6.5. Natural organic matter (NOM) surrogates and trihalomethane formation potential (THMFP) were determined to study their reduction. The obtained results showed that total organic carbon (TOC) were gradually reduced from the average value of about 6.1 mg/L to a level of about 4.0 mg/L by alum and ferric chloride dosages of approximately 40 mg/L. Moreover, dissolved organic carbon (DOC) were reduced from an average value of 5.1 mg/L to a level of about 4.0 mg/L by alum and ferric chloride dosages of approximately 40 mg/L. Specific ultraviolet absorption (SUVA) were decreased from an average value of approximately 4.7 L/mgm to a level of about 2 L/mgm by alum and ferric chloride dosages of approximately 20 mg/L. In addition, chlorine demands at 1 day reaction were the same as those of 7-day demands with a correlation coefficient of 0.98 (n = 10, correlation significant at the 0.01 level). Interestingly, chloroform of approximately 65 and 60% of total THMFP was found as the predominant THMFP species in treated industrial estate wastewater and reclaimed water, respectively, in comparison with other THM species. Maximum THMFP percentage removal of 25 and 28 by using alum and ferric chloride dosages of about 80 mg/L at pH 5.5 and 5 were obtained, respectively, at the examined conditions.     

水利水电工程网络进度计划标准化系统研发

水利水电工程网络进度计划是施工组织设计的重要组成部分。针对目前大多数网络进度计划软件在进度计划生成、分析等方面提供的功能有限,使得网络进度计划编制费时、费力,效率不高,且标准化程度不高等问题,本文在分析了水利水电工程网络进度计划标准化内涵的基础上,对网络进度计划标准化的基本内容进行了研究;在此基础上设计开发了水利水电工程网络进度计划标准化系统,详细介绍了网络进度计划辅助生成、分析、评价与审阅,以及成果输出等功能。该系统不仅界面友好、直观可视化,而且提供了强大的计算及优化功能,大大提高了工程人员网络进度计划编制的效率和质量,为网络进度计划快速分析和优化提供了一种新的思路和手段。     

AnMBR处理活性黑KN-B印染废水

实验对厌氧膜生物反应器(AnMBR)处理活性黑KN-B印染废水进行了探讨.研究了厌氧反应器内活性污泥的驯化培养状况,考察了厌氧反应器与管式超滤膜对印染废水BOD5,COD的去除作用,并对厌氧反应器产气量、出水的碳酸氢盐碱度和VFA进行了分析,通过UV-Vis光谱图分析了AnMBR对活性黑KN-B的脱色效果.结果表明,液流较低的低负荷启动方式使该AnMBR活性污泥的驯化培养顺利进行,厌氧反应器污泥床区域的污泥浓度培养至35 g/L;AnMBR对废水BOD5和COD的去除率分别达到90%和85%以上;该厌氧反应器的活性污泥体系和缓冲体系相对稳定,出水的碳酸氢盐碱度和VFA分别在16~18mmol/L与1.0~3.5 mmol/L的范围内波动,pH稳定在7.70~8.00之间;AnMBR对500mg/L的活性黑KN-B废水的脱色率能达到90%以上.     

Flocculation behaviour of model textile wastewater treated with a food grade polysaccharide

In this study, the application of a food grade polysaccharide namely Plantago psyllium mucilage has been assessed for the removal of dyes from model textile wastewater containing golden yellow (C.I. Vat Yellow 4) and reactive black (C.I. Reactive Black 5). A series of contact time experiments were conducted to assess the system variables such as concentrations of mucilage and dyes and pH. This mucilage reduces the dye concentration by flocculation and settling. The optimal flocculant concentration required to affect flocculation is independent of dye concentration within the range examined. The dye removal obtained was influenced by the salts concentrations in the wastewater sample. The flocculation efficiency was sensitive to pH when pure aqueous solutions of dyes were used, but it was relatively unaffected by pH change when salts were added to the dye solutions. The experimental results show that the mucilage is more effective for removal of solubilised vat dye than for reactive black.     

Optimum lipid production using agro-industrial wastewater treated microalgae as biofuel substrate

Abundant wastewater discharges from palm oil industries in tropical nations being a valuable resource of biodiesel need proper exploration. Research hinted that such wastewater as economical nutrient source or substrate can support the cultivation of microalgae. In this experiment, we have tested the growth and lipid production of five different microalgal strains in palm oil mill effluent (POME). POME as a biofuel substrate is demonstrated to be lucrative for microalgae-assisted lipids production. POME is rich in macro- and micronutrients can be used as a growth medium for algal growth in order to reduce the growth medium cost and environmental pollutions. Among the five microalgal strains tested, Chlorella sorokiniana revealed optimum biomass and lipid production. The productivity was evaluated in terms of chlorophyll content, growth rate, biomass, and lipid content, which discerned to be 0.099/day, 8.0 mg/L day and 2.68 mg/mg cell dry weight (CDW). Furthermore, in this study, an optimization study was carried out to enhance the microalgae to produce high lipid content using carbon-to-nitrogen ratio and different light/dark periods. The presence of nitrogen combined glucose (with a carbon-to-nitrogen ratio 100:7) as an alternative source to carbon displayed higher lipid production of 2.68 (mg/mg CDW) by C. sorokiniana. This study confirms that 8:16 h light/dark condition at C:TN ratio of 100:7 supported to produce high lipid content of 17 mg lipid/mg CDW. The above results revealed that POME could be a suitable growth media for the alga C. sorokiniana to improve the maximum lipid yield for biofuels production.     

膜技术处理印染废水研究进展

介绍了膜分离及集成技术在印染水处理中的应用,分析了膜污染存在的原因及解决膜污染问题的研究现状,重点介绍具有自清洁功能的电催化膜及其抗污染机理.最新结果显示,电催化膜利用膜分离与间接氧化协同作用能够实现印染废水高效降解,是一种绿色环保的污水处理新技术,具有广阔的应用前景.开发具有抗污染、长寿命、高通量的膜材料以及集成技术...     

Removing endocrine-disrupting compounds from wastewater

This brief article highlights research work that is being carried out at the Institut für Verfahrenstechnik, RWTH-Aachen, Aachen, Germany, which is seeking to develop ways of removing endocrine-disrupting compounds from wastewater using membrane processes.     

陶瓷膜法处理退浆废水工艺研究及工业化装置运行评价

针对以聚甲基丙烯酸甲酯为主要成分的退浆废水,采用孔径为50nm的陶瓷膜过滤,实现废水的资源化利用.采用两级串联先循环后浓缩的操作方式.循环过滤时,拟稳态通量为423L/(m2·h)和453L/(m2·h).循环结束后进行浓缩,浓缩倍数达到22倍时通量为66L/(m2·h)和54L/(m2·h);膜对COD的截留率为87.5%,产水浊度低于1NTU,废水中的氢氧化钠等小分子物质均透过膜层进入渗透液;膜污染是以聚甲基丙烯酸酯在膜表面形成滤饼为主;碱洗及酸洗膜通量恢复至新膜的95%以上.陶瓷膜出水回用于生产过程;工业化陶瓷膜运行稳定,经济效益显著.     

Enhancement of bioseparation and dewaterability of domestic wastewater sludge by fungal treated dewatered sludge

A promising biological, sustainable, non-hazardous, safe and environmental friendly management and disposal technique of domestic wastewater sludge is global expectation. Fungal entrapped biosolids as a result of prior fungal treated raw wastewater sludge was recycled to evaluate its performance as inoculum for bioseparation/bioconversion of supplemented sludge in view of continuous as well as scale up wastewater sludge treatment. Encouraging results were achieved in bioseparation of suspended solids and in dewaterability/filterability of treated domestic wastewater sludge. Fungal entrapped biosolids offered 98% removal of total suspended solids (TSS) in supplemented sludge treatment at 6-day without nutrient (wheat flour, WF) supply. Consequently, 99% removal of turbidity and 87% removal of chemical oxygen demand (COD) were achieved in supernatant of treated sludge. The lowest value (1.75 x 10(12)m/kg) of specific resistance to filtration (SRF) was observed at 6-day after treatment, which was equivalent to the 70% decrease of SRF. The all results except SRF were not influenced further in treatments accompanied with WF supplementation. The present treatments offered significant (P相似文献   

Development of a high performance electrochemical wastewater treatment system

In order to construct a high performance electrochemical system for practical use in industrial and municipal wastewater treatment, laboratory scale electrochemical experiments were performed to select anode materials by applying pulse voltage. Based on the results obtained from laboratory experiments, a pilot plant of electrochemical treatment system (0.3 m3 h(-1)) was successfully developed, in which electrocoagulation and electrooxidation processes were used. The performance of the treatment system was evaluated by treating domestic wastewater, pond water containing algae and wastewater from hog raising. As a result, production of hydroxyl radicals detected with p-nitrosodimethylaniline (RNO) at Ti/RuO(2)-TiO(2) anode was larger than with a platinum anode, and hydroxyl radicals were not detected at Ti anode. Moreover, a significant difference in electrocatalytic properties for ammonia oxidation between platinum and Ti/RuO(2)-TiO(2) electrodes was not observed from the cyclic voltammogram. The removal of T-N, T-P, NH(4)-N and COD from domestic wastewater and pond water containing algae was approximately 90%, while the removal of chlorophyll-a (chl-a) of algae was approximately 100%. Although the electrochemical treatment system was effective on biologically treated wastewater from hog raising, the treatment of raw wastewater was not remarkable. Therefore, the electrochemical treatment system requires pretreatment when used with wastewater containing high concentrations of suspended solids.     

Electrodialytic removal of cadmium from wastewater sludge

This paper presents for the first time laboratory results demonstrating electrodialytic removal of Cd from wastewater sludge, which is a method originally developed for soil remediation. During the remediation a stirred suspension of wastewater sludge was exposed to an electric dc field. The liquid/solid (ml/g fresh sludge) ratio was between 1.4 and 2. Three experiments were performed where the sludge was suspended in distilled water, citric acid or HNO3. The experimental conditions were otherwise identical. The Cd removal in the three experiments was 69, 70 and 67%, respectively, thus the removal was approximately the same. Chemical extraction experiments with acidic solutions showed that 5-10 times more Cd could be extracted from decomposed sludge than from fresh sludge. It is likely that the mobilization of Cd during decomposition of the sludge contributes to the efficient removal of Cd by the electrodialytic method. Extraction experiments and electrodialytic remediation using distilled water as enhancement agent showed that 0.3% Cd could be extracted from decomposed sludge during 1 week in closed flasks, whereas 69% was removed during 2 weeks of electrodialytic remediation in a stirred solution in contact with atmospheric air. A combination of aerobic decomposition and electrodialytic treatment could be a promising method for Cd removal from wastewater sludge, and thus Cd could be removed without the addition of chemicals to the sludge.     

Ultra-low resistivity in-situ phosphorus doped Si and SiC epitaxy for source/drain formation in advanced 20 nm n-type field effect transistor devices

We present an effective epitaxy process based on a cyclical deposition-etch (CDE) technique to obtain ultra-low resistivity in situ phosphorus-doped silicon carbon (SiCP) layers for raised source/drain applications. The combined low process temperature and high growth rate of the CDE technique is shown to maximize the incorporation of phosphorus and carbon into the crystal. We also present a complementary procedure based upon high-temperature annealing to further improve the phosphorus activation. This process and procedure enable the formation of raised SiCP source/drains on advanced 20 nm fully-depleted-silicon-on-insulator devices with a carrier density up to 3 × 10²⁰ cm^− 3 for 5 × 10²⁰ cm^− 3 total P, and with fully-substitutional carbon in the range from 0% to 2%. It was found that a 1250 °C millisecond laser anneal improves resistivity by 30% and 42% for SiP and SiC_2.1%P, respectively. This result is in contrast with a 1060 °C spike anneal, where the gain in activated P is shown to be insignificant for SiCP. It is shown that the formation of C clusters or precipitates during spike anneal adversely affects P activation. With an optimized annealing process, resistivity values as low as 0.46 MΩ cm for SiC_2.1%P and 0.3 MΩ cm for SiP were obtained.