The relationship between soil color and iron oxide content in a surface-flow constructed wetland that successfully treats acid mine drainage (AMD) is examined with regard to its potential importance to wetland treatme...
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The relationship between soil color and iron oxide content in a surface-flow constructed wetland that successfully treats acid mine drainage (AMD) is examined with regard to its potential importance to wetland treatment of AMD. Twenty-one oxidized surficial soil samples (<5 cm depth) were collected along a 100-meter wetland transect and were characterized for Munsell color and iron oxide content. Soil color, expressed in terms of both a redness index as well as dominant wavelength, was found to be significantly correlated (p < 0.001) with iron oxide content. In addition, an apparent red-shift in soil color was observed from the wetland effluent toward the influent in response to increasing concentrations of iron in both the soil and the drainage water. If this relationship between soil color-iron oxide content-iron removal is shown to exist for other surface-flow AMD wetlands, evaluation of soil color can give a relatively quick and inexpensive estimate of iron retention for a given influent iron concentration entering a wetland.
Three brominated trihaloacetaldehydes (THAs), bromodichloroacetaldehyde, dibromochloroacetaldehyde and tribromoacetaldehyde, were identified, by gas chromatography-mass spectrometry, in ozonated and chlorinated aqueou...
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Three brominated trihaloacetaldehydes (THAs), bromodichloroacetaldehyde, dibromochloroacetaldehyde and tribromoacetaldehyde, were identified, by gas chromatography-mass spectrometry, in ozonated and chlorinated aqueous fulvic acid solutions containing inorganic bromide. Mass spectra of these THAs were obtained in the electron-impact and positive chemical-ionization modes. The significance of the formation of brominated THAs on water quality and future disinfection by-product regulation is discussed.
Emerging contaminants(ECs)in drinking water pose threats to public health due to their environmental prevalence and potential *** occurrence of ECs in our drinking water supplies depends on their physicochemical prope...
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Emerging contaminants(ECs)in drinking water pose threats to public health due to their environmental prevalence and potential *** occurrence of ECs in our drinking water supplies depends on their physicochemical properties,discharging rate,and susceptibility to removal by water treatment *** health effects of long-term exposure to ECs justify their regular monitoring in drinking water *** this review article,we will summarize the current status and future opportunities of surface-enhanced Raman spectroscopy(SERS)for EC analysis in drinking *** principles of SERS are first introduced and a comparison of SERS and liquid chromatography-tandem mass spectrometry in terms of cost,time,sensitivity,and availability is ***,we discuss the strategies for designing effective SERS sensors for EC analysis based on five categories—per-and polyfluoroalkyl substances,novel pesticides,pharmaceuticals,endocrine-disrupting chemicals,and *** addition to maximizing the intrinsic enhancement factors of SERS substrates,strategies to improve hot spot accessibilities to the targeting ECs are equally *** is a review article focusing on SERS analysis of ECs in drinking *** discussions are not only guided by numerous endeavors to advance SERS technology but also by the drinking water regulatory policy.
Results of a laboratory study are presented that describe hydraulic and mechanical properties of a compacted compost derived from a mixture of municipal solid waste and treatment plant sludge. The objective of the stu...
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Results of a laboratory study are presented that describe hydraulic and mechanical properties of a compacted compost derived from a mixture of municipal solid waste and treatment plant sludge. The objective of the study was to determine if compacted compost has properties desirable of a hydraulic barrier used in liners and final covers of landfills. Ordinarily, the hydraulic barrier is constructed with compacted clay and/ or a geomembrane. Laboratory tests were performed to determine the particle size distribution, compaction characteristics, hydraulic conductivity and shear strength of the compacted compost. Tests have also been conducted to evaluate: (1) the resistance of compost to changes caused by desiccation and freeze-thaw, (2) the effects of extended permeation and (3) the concentration of contaminants leached during permeation. The results of the study show that compost can be compacted into a dense mass with low hydraulic conductivity (2 x 10-10 m s-1). It is also more resistant to increases in hydraulic conductivity caused by desiccation and freeze-thaw than compacted clay. Compacted compost also has greater shear strength than compacted clay and therefore is likely to remain stable on typical landfill slopes. However, contaminants considered hazardous, such as heavy metals, were leached from the compost at levels exceeding United States drinking water standards. The results suggest that the compost used in this study has hydraulic and mechanical properties desirable of a hydraulic barrier and further detailed study of its use is warranted.
Aquatic humic substances can be removed by chemical coagulation during water treatment. Hydrolyzing metals such as Al(III) and Fe(III), as well as commercially available cationic polyelectrolytes, can effectively remo...
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Aquatic humic substances can be removed by chemical coagulation during water treatment. Hydrolyzing metals such as Al(III) and Fe(III), as well as commercially available cationic polyelectrolytes, can effectively remove humic substances prior to chlorination, thus reducing the formation of trihalomethanes. Synthetic waters, produced by adding soil-extracted fulvic acids to distilled water containing a clay source and various salts, have some merit in approximating the behavior of aquatic humic substances during chemical coagulation; however, caution must be exercised in the interpretation and applicability of the results.
Artificial support material was examined to determine the removal capacity of organic pollutants and nutrients on laboratory scale using PFR system. The experiment was performed using artificial water with similar cha...
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Internal loading of P was implicated as a major eutrophicating factor in Long Lake, Washington (Kitsap County) [USA]. As a result of such loading, summer total P concentrations approach or exceed 100 .mu.g P l-1. Most...
Internal loading of P was implicated as a major eutrophicating factor in Long Lake, Washington (Kitsap County) [USA]. As a result of such loading, summer total P concentrations approach or exceed 100 .mu.g P l-1. Most of the summer loading of P is thought to have been released directly from the rich, flocculent sediment in the mid and northern part of the lake as a result of high pH (up to 10) related to phytoplankton photosynthesis. The lake also supports a dense submersed macrophyte crop (areal weighted mean dry weight of .apprx. 220 g m-2) composed primarily of Elodea densa. Although excretion of P from healthy E. densa was minimal, the potential contribution of P indirectly from sediment via macrophyte uptake and subsequent decomposition in the winter was on the order of 200-400 kg yr-1 or .apprx. 25-50% of the external loading. Nevertheless, loading of P during predrawdown summers is thought to have originated largely as a direct release from sediment due to high pH. Estimates of sediment P release determined from laboratory experiments, mass balance and core analyses ranged from 2.2-5.6 mg m-2 day-1. As a component of the restoration program, the lake (mean depth of 2 m) was drawn down nearly 2 m for 4 mo. during the summer and fall of 1979. The lake''s trophic status was expected to improve due to sediment consolidation and/or macrophyte reduction. The drawdown resulted in an 84% reduction in macrophyte biomass in 1980 but minimal sediment consolidation (0.1 m). Winter decomposition of the much smaller macrophyte crop, apparently provided insufficient P in the spring to stimulate phytoplankton and to enrich midlake sediments, which has probably occurred in previous years. Low water column pH during the postdrawndown summer of 1980 resulted from relatively low rates of plankton photosynthesis. During the summer of 1980 internal loading of P was reduced and total P remained below 50 .mu.g l-1.
The increasing CO2 concentration in the atmosphere has substantial impacts on the global temperature. For energy sustainability and minimization of the effects of global warming, an approach to understand CO2 capturin...
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The kinetics of the catalyzed autoxidation of H2S to S, S2O3 and sulfate in aqueous solution was investigated potentiometrically over the pH range 5-12. The catalytic effects of Co(II), Ni(II) and Cu(II) 4,4''...
The kinetics of the catalyzed autoxidation of H2S to S, S2O3 and sulfate in aqueous solution was investigated potentiometrically over the pH range 5-12. The catalytic effects of Co(II), Ni(II) and Cu(II) 4,4'',4",4"''-tetrasulfophthalocyanine were determined and differences in catalytic ability were explained in terms of relative capacity of the octahedral complexes to reversibly bind O2. Kinetic data were analyzed in terms of a bisubstrate Michaelis-Menten rate law. The rate law and other data indicate that the catalyzed reaction proceeds via the formation of a tertiary-activated complex in which HS- and O2 reversibly bind with CoTSP2-. pH variations were explained in terms of the acid dissociation of H2S, general base catalysis and deprotonation of pyrrole nitrogens within the phthalocyanine ring.
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