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1.
Riverine organic carbon in the Xijiang River (South China): seasonal variation in content and flux budget 总被引:11,自引:0,他引:11
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Y. L. Li J. W. Liu J. Y. Chen Y. F. Shi W. Mao H. Liu Y. Li S. He J. K. Yang 《International Journal of Environmental Science and Technology》2014,11(1):233-240
High water and organic content of sewage sludge constricts its reuse and disposal. It is often necessary to solidify/stabilize the dewatered sludge with solidifying agents before landfill disposal. In this study, the sewage sludge was conditioned with skeleton builders, i.e., fly ash and lime combined with ferric chloride for the purpose of improving the dewatering efficiency. The dewatered sewage sludge was then directly reused as landfill cover materials since the skeleton builders also play a role in solidification of sludge. The geotechnical properties of the dewatered sewage sludge were investigated. The results show that the plasticity index of the dewatered sludge increases compared to that of the dewatered sludge without any conditioner, and the permeability coefficient changes from 10?8 to 10?5 cm s?1. Furthermore, the strength of specimens increase with curing days. Microstructure analyses reveal that the main hydrated products are calcium silicate hydrate and ettringite, which contribute to the solidification/stabilization of the dewatered sludge. The results indicate that the dewatered sewage sludge conditioned with skeleton builders can be used as landfill covers. This study provides an alternative for traditional sewage sludge treatment and disposal. 相似文献
3.
采用自主改装的变压头黏土渗透仪,模拟疏浚淤泥脱水过程中水分在淤泥颗粒多孔介质中的迁移运动过程,通过测定疏浚淤泥脱水过程中渗透系数与过滤常数、渗水量与滤液量、泥饼含水率与孔隙率,探究了负载压力为100 kPa时,不同负载方式(负载时间及负载压力梯度变化)对疏浚淤泥脱水过程中过滤和渗流规律的影响。研究发现:负载下的过滤和渗流同时进行,负载1 h期间,前期0~40 min内过滤占主导地位,后期40~60 min内渗流起关键作用。负载压力梯度由原来1 h内间隔变化1次,变为以20 kPa为梯度递增变化5次,随着压力变化梯度减小,渗透系数、过滤常数增加,淤泥脱水性能得到较明显的改善,并且前期负载压力越小,脱水效果越好。 相似文献
4.
Lead distribution on a public shotgun range 总被引:1,自引:0,他引:1
James R. Craig David Edwards Donald J. Rimstidt Patrick F. Scanlon Thomas K. Collins Oliver Schabenberger Jeffrey B. Birch 《Environmental Geology》2002,41(8):873-882
5.
H. Khorsandi Ph.D. H. Movahedyan Ph.D. B. Bina Ph.D. H. Farrokhzadeh M.Sc. 《International Journal of Environmental Science and Technology》2011,8(2):417-424
In this research, a novel laboratory scale anaerobic/upflow sludge blanket filtration combined bioreactor was designed and operated to improve the efficiency of the upflow sludge blanket filtration process for the simultaneous removal of phosphorus and nitrogen from wastewater. The anaerobic/upflow sludge blanket filtration technique was developed by adding an anaerobic reactor to its influent and operated by varying the main process parameters in order to gain the optimum conditions. The results showed that biological removal efficiency of nitrogen and preservation of sludge blanket strongly depend on wastewater characteristics, hydraulic retention time, sludge age and process controlling parameters. The combined bioreactor performed a total nitrogen removal efficiency of 96.6 % with the sludge age of 25 days, total hydraulic retention time of 24 h and optimum “chemical oxygen demand/nitrogen/phosphorus” ratio of 100/ 5/1. This ratio also improved the compaction quality of sludge blanket in the upflow sludge blanket filtration clarifier. The average specific nitrification and denitrification rates occurred during the process can be expressed as 4.43 mg NOx-N produced/g VSS.d and 5.50 mg NOx-N removed/g VSS.d at the optimum ratio, respectively. To avoid sludge rising due to denitrification process, the optimum total hydraulic retention time of 16 to 24 h was achieved based on the effluent quality. This study suggested that the anaerobic/upflow sludge blanket filtration bioreactor at the optimum operational conditions can be an effective process for removal of nutrients from municipal wastewater. 相似文献
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Hydro-mechanical evaluation of stabilized mine tailings 总被引:3,自引:0,他引:3
8.
Influence of acidic atmospheric deposition on soil solution composition in the Daniel Boone National Forest,Kentucky, USA 总被引:1,自引:0,他引:1
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10.
Sediment masses and heavy-metal accumulation rates for the recent deposits of the Göta älv estuary were calculated using a GIS. Total masses of 4,000 t Zn and >20 t Hg were recorded, of which 367 t Zn and >0.72 t Hg occur in the inner estuary, the Göteborg harbour, and 3,657 t Zn and 19 t Hg are in the outer estuary, suggesting a high trapping efficiency of the estuary. The accumulation rates are 5 g m-2 year-1 Zn and 0.01 g m-2 year-1 Hg in the harbour, and 1.5 g m-2/year-1 Zn and 0.007 g m-2 year-1 Hg in the outer estuary. The Zn and Hg accumulation rates are highest close to the outlet of a sewage treatment plant, and decrease by a factor of 5 for Zn, and a factor of 2 for Hg in the outer estuary. The accumulation rates in the outer estuary decrease after 1980 A.D. 相似文献
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GIS applied to determine environmental impact indicators made by sand mining in a floodplain in southeastern Brazil 总被引:4,自引:0,他引:4
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Arsenic pollution in groundwater from Hetao Area,China 总被引:3,自引:0,他引:3
14.
Y. Shi J. Yang S. Liang W. Yu J. Xiao J. Song X. Xu Y. Li C. Yang X. Wu J. Hu B. Liu H. Hou 《International Journal of Environmental Science and Technology》2016,13(9):2283-2292
Sludge samples taken from different sources and times may have different characteristics that could affect dewatering performance. In this study, 20 sludge samples from five wastewater treatment plants and different seasons in 1 year were characterized. Pearson correlation analysis indicated that solid content (SC), total suspended solid (TSS), polysaccharides and proteins contents had positive correlations with the capillary suction time (CST), whereas volatile suspended–solid/total suspended solid (VSS/TSS) exhibited negative correlations with CST. Moreover, no correlations between CST and specific resistance to filtration were found among these different sludge samples. The principal component analysis confirmed that only two group variables could represent most of the sludge characteristic parameters. The first set of variables represents the particulate nature of the biotic factors (SC, VSS/TSS, SCOD, TSS, polysaccharides and proteins), and the second set is the pH. CST could not be a reasonable indicator of dewaterability in sludge deep dewatering by Fe2+/S2O8 2?-phosphogypsum composite conditioning. Furthermore, the results of diaphragm filter press dewatering showed that initial SC and VSS/TSS were the most dominant sludge characteristics affecting the solid content of dewatered cake (R p = 0.610, p = 0.016; R p = ?0.838, p = 0.000, respectively) with Fe2+/S2O8 2?-phosphogypsum composite conditioning. Results from this study suggest that dewatering performance is predictable by sludge characteristics parameters for Fe2+/S2O8 2?-phosphogypsum conditioning. 相似文献
15.
A regional study of saltwater intrusion in southeastern Nigeria based on the analysis of geoelectrical and hydrochemical data. 总被引:1,自引:1,他引:1
Vertical electrical sounding (VES) and hydrochemical data have been used to examine the extent of saltwater intrusion into shallow aquifers (depth<300 m) beneath the coastal plains of southeastern Nigeria underlain by siliciclastic sedimentary rocks of the Cenozoic Niger Delta. The VES data indicate that the coastal regions not affected by saltwater are characterised by K-and H-type geoelectrical curves and models in which high-layer resistivities (in excess of about 100 ohm-m) reflect the presence of freshwater aquifers at depths greater than 5 m below the surface. By contrast, Q-type curves and models denote saltwater-infiltrated islands with the upper boundary of the saline zone at depths of about 25 to 30 m. Chemical analysis results of precipitation and ground water show that, compared to coastal and continental sites, island localities have higher concentrations of major ions (Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, SO42-, NO3) due to saltwater intrusion. In addition, these ions, which also characterise seawater, show very good correlations (>0.70). Furthermore, the coastal sites are marked by Ca-Cl and Ca-HCO3 water types whereas Na-Cl dominated both the islands ( at depths greater than 20 m) and the seawater. This gives an indication of seawater contamination. Seawater contamination is also indicated by the results of five assessment parameters as follows: high chloride concentration (>500 mg/l), high saturation index (halite>10-6), high ionic strength (>0.05), low formation resistivity (<25 ohm-m), and low formation factor (<0.05). Two of these parameters (chloride concentration, ionic strength) have been used to compose an assessment scheme with five major classes (AA, BB, CC, DD, EE) corresponding to various degrees of salinity. Generally in the study area, saltwater contamination is a feature of island locations at depths greater than about 20 m. Water within the inland coastal regions is fresh. 相似文献
16.
Regional Metamorphism of the Waits River Formation, Eastern Vermont: Delineation of a New Type of Giant Metamorphic Hydrothermal System 总被引:4,自引:0,他引:4
Metamorphic isograds and time-integrated fluid fluxes were mappedover the 1500 km2 exposure of the Waits River Formation, easternVermont, south of latitude 4430'N. Isograds based on the appearanceof oligoclase, biotite, and amphibole in metacarbonate rocksdefine elongated metamorphic highs centered on the axes of twolarge antiforms. The highest-grade isograd based on the appearanceof diopside is closely associated spatially with synmetamorphicgranitic plutons. Pressure, calculated from mineral equilibria,was fairly uniform in the area, 7 1.5 kb; calculated temperatureincreases from {small tilde} 480C at the lowest grades in thearea to {small tilde} 575C in the diopside zone. CalculatedXco2f equilibrium metamorphic fluid increases from <0-03at the lowest grades to 0.2 in the amphibole zone and decreasesto 0.07 in the diopside zone. Time-integrated fluid fluxesincrease with increasing metamorphic grade, with the followingmean values for each metamorphic zone (in cm3/cm2): ankerite-oligoclasezone, 1 x 104; biotite zone, 7 x 104; amphibole zone, 2 x 105;diopside zone, 7 x 105. The mapped pattern of time-integrated fluxes delineates twolarge deep-seated ({small tilde} 25-km depth) regional metamorphichydrothermal systems, each centered on one of the major antiforms.Fluid flowed subhorizontally perpendicular to the axis of theantiforms from their low-temperature flanks to their hot axialregions and drove prograde decarbonation reactions as they went.Along the axes of the antiforms fluid flow was further focusedaround synmetamorphic granitic intrusions. In the hot axialregion fluid changed direction and flowed subvertically outof the metamorphic terrane, precipitating quartz veins. Estimatesof the total recharge, based on progress of prograde decarbonationreactions, nearly match estimates of the total discharge, basedon measured quartz vein abundance, (2-10) x 1012 cm3 fluid percm system measured parallel to the axes of the antiforms. Withinthe axial regions fluids had lower XCO2 and rocks record greatertime-integrated fluxes close to the intrusions than at positionsmore than {small tilde} 5 km from them. The differences in bothfluid composition and time-integrated flux can be explainedby mixing close to the intrusions of regional metamorphic fluidsof XCO2/ with fluids from another source with XCO2{small tilde}0 in the approximate volume ratio of 1:2. 相似文献
17.
Contact-mctamorphic assemblages in ophicarbonate from the Bergellaureole correspond either to model isobaric invariant T-XCO2points [Atg-Cal-Di-Tr-Fo (6 samples) and Atg-Cal-Tr-Fo-Dol (2)]or to isobaric univariant T-XCO2, curves [Tr-Cal-Di-Atg (18),Tr-Dol-Atg-Cal (1), Atg-Cal-Fo-Di (1), and Atg-Cal-Tr-Fo (1)].Calcite-dolomite thermometry and mineral-fluid equilibria inthe invariant assemblages record T=440540C at P=35kbar. Equilibrium metamorphic fluids were very H2O rich withX CO2,=00010027. In the invariant assemblagesTr + Fo were produced by prograde decarbonation-dehydrationreactions. In contrast, measured modes and reaction texturesin samples with univariant assemblages indicate thai Tr wasproduced by carbonation reactions. The apparent paradox of simultaneousdecarbonation reactions in the model isobaric invariant assemblagesand carbonation reactions in univariant assemblages is resolvedby local mineral-fluid equilibrium and fluid flow through ophicarbohatesin the direction of decreasing temperature as the aureole heated.Time-integrated flux (q) was computed from measured reactionprogress in 28 samples for models of both horizontal and verticaldown-temperature flow. Results are similar, with q decreasingrapidly from (0251) 105 cm3 fluid/cm2 rock1317 km from the intrusion to 006105cm3/cm2 at 1840 km. The decrease in q ismore consistent with vertical than horizontal flow. Variationsin time-integrated flux of more than an order of magnitude arerecorded by samples from the same outcrop. The absence of carbonatein adjacent metaperidotite indicates that flow was confinedto the ophicarbonate. Channelized, spatially heterogeneous,vertical flow can be explained by the brecciation and strongvertical foliation of the ophicarbonate relative to surroundingmassive metaperidotite. Generation of metamorphicfluids by decarbonation-dehydrationreactions within the ophicarbonates explains larger averageflux 12 km from the intrusion compared with more distalpoints. KEY WORDS: Bergell; contact metamorphism; fluid flow; ophicarbonate
*Telephone: (410) 516-8121. Fax: (410) 516-7933 相似文献
18.
Z. H. Zhang Y. J. Feng P. Gao J. F. Liu N. Q. Ren 《International Journal of Environmental Science and Technology》2012,9(2):247-256
The adsorption and desorption behaviors of 17??-ethinylestradiol on various sludges derived from different treatment units of a sewage treatment plant were investigated using batch equilibration experiments. The results showed that adsorption process could be well described by pseudo-second-order kinetic model and fast adsorption played a main role. Adsorption ability varied as the order of aerobic sludge????anoxic sludge????primary sludge?>?sludge cake?>?anaerobic sludge. Adsorption/desorption isotherms were well fitted by the modified Freundlich model, and $ K_{f}^{\prime } $ values increased with the organic matter content. Thermodynamic analysis indicated that 17??-ethinylestradiol adsorption/desorption was exothermic and conducted spontaneously. After heat treatment for removing the organic carbon, $ K_{f}^{\prime } $ values decreased by more than 78%, but organic carbon normalized adsorption constant was 7.76?C29.51?mg/g. The 17??-ethinylestradiol adsorption capacity was found to decrease from 0.95?C1.39 to 0.44?C0.49?mg/g with sludge concentration increasing from 500 to 4,000?mg/L, being almost unchanged at pH 3?C10 and sharply decreasing with pH?>?10. The adsorption capacity was also found to fluctuate in the range of 2.0?C3.0?mg/g when Ca2+ concentration was <0.5?mol/L and increased rapidly above 0.5?mol/L. Addition of methanol and acetonitrile could improve 17??-ethinylestradiol desorption effect, which increased with the content of organic solvents, and the desorption degree of acetonitrile was higher than methanol. 相似文献
19.
D. Tao B. K. Parekh J. T. Liu S. Chen 《International Journal of Mineral Processing》2003,70(1-4):235-249
Ultrafine coal dewatering is of great importance to the coal industry due to its impacts on the handling and utilization characteristics of coal products. Commercially available filtration techniques are either ineffective or costly for dewatering of ultrafine coal to the desired moisture level of about 20%. Considerable efforts have been devoted to understanding the dewatering process and developing new technologies for applications in the coal industry. Most of the previous work on ultrafine coal filtration was focused on the final filter cake moisture and few studies have been conducted to investigate the filtration kinetics. The present investigation was undertaken to better understand the kinetics of vacuum filtration of ultrafine coal under various conditions. The filtrate weight was continuously monitored using a precise load cell during the entire filtration process. Operating parameters such as vacuum pressure and reagent conditioning time were examined for their impacts on filtration kinetics. Use of cationic and anionic flocculants showed significant improvement in filtration kinetics. Kinetic data obtained from the study were used to determine the fundamental parameters of filtration such as cake permeability, specific cake resistance, and filter medium resistance using the integrated form of the Darcy's law. 相似文献
20.
A new thermobarometer, based on the equilibrium:
has been calibrated with experiments carried out in the piston-cylinderapparatus. Reversed equilibria were obtained using well-calibrated2.54 cm NaCl furnace assemblies and Ag80Pd20capsules with fO2bufferedat or near iron-wustite. The equilibrium is located between5.25.4, 6.66.8, and 8.68.8 kb at 880, 940,and 1020?C, respectively, and at 5.2 and 8.8 kb between 865880and 10201030?C, respectively. X-ray refinement data indicate that the hercynite (a = 8.15546?) has approximately 18 per cent inverse character. M?ssbauerspectra reveal that 4 mol per cent of the Fe is ferric (2 percent magnetite component). Broad Mossbauer lines and a Fe2+energy level splitting of 3.7 kJ mol1 calculated fromthe Mossbauer spectra are consistent with the X-ray determineddegree of inversion, although no separate octahedral Fe2+ spectraldoublet is resolved. Calibration of this equation allows calculation of the equilibrium:
Thermobarometers based on the above equilibria are widely applicablein granulite fades rocks and yield pressure/temperature datathat are consistent with other well-calibrated barometers andthermometers. 相似文献