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CONTRIBUTION OF BENTHIC BLUE-GREEN-ALGAL RECRUITMENT TO LAKE POPULATIONS AND PHOSPHORUS TRANSLOCATION

FRESHWATER BIOLOGY 1992年第2期27卷 249-260页

作者： BARBIERO, RP WELCH, EB Environmental Engineering & Science Program Department of Civil Engineering University of Washington Seattle WA U.S.A.

1. A two-season investigation was undertaken to determine the contribution of benthic recruitment to the population development of several species of blue-green algae. 2. Gloeotrichia echinulata populations were shown to be heavily subsidized by benthic recruitment, deriving on average 40% of their planktonic colonies from the benthos. 3. Benthic recruitment of Aphanizomenon flos-aquae;Anabaena flos-aquae and a second Anabaena species contributed less than 2% to planktonic increases, while Microcystis aeruginosa recruitment was negligible. 4. Phosphorus translocation via migrating G. echinulata accounted for most of the phosphorus (P) in the planktonic colonies, and constituted a significant portion of the internal loading of the lake. 5. Estimated P translocation via Aph. flos-aquae was relatively minor, although there was evidence of luxury uptake in the benthos.

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Biotreatability test of bleach wastewaters from pulp and paper mills

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WATER SCIENCE AND TECHNOLOGY 1997年第2-3期35卷 101-108页

作者： Wang, X Mize, TH Saunders, FM Baker, SA Environmental Engineering Program School of Civil and Environmental Engineering Georgia Institute of Technology Atlanta GA 30332-0512 USA

Research is focused on an integrated way to simultaneously optimize the bleaching operations and subsequent wastewater treatment for pulp and paper mills. Bleach wastewaters from ClO2-bleached pulping studies at Institute of Paper Science and Technology (IPST) were used as the feed for batch reactors to test and rank the treatability and kinetics. The key aspect of the system is the use of sequential anaerobic/aerobic phases to enhance reductive dehalogenation of chloro-organic materials. Two continuous reactor systems, one operated in an anaerobic-aerobic mode and a second in an aerobic-aerobic mode, received bleaching wastewater obtained from a full-scale plant. Acclimated cultures from both continuous reactors were used to quantify the AOX (Adsorbable Organic Halide) and COD removal from various bleaching wastewaters. In general, the sequential anaerobic/aerobic treatment of bleach wastewater can improve both biotreatability and degradation rates. (C) 1997 IAWQ.

关键词： anaerobic/aerobic biotreatability bleach wastewater dechlorination single-sludge

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INTEGRATING SANDWICH - A NEW METHOD OF MEASUREMENT OF THE LIGHT-ABSORPTION COEFFICIENT FOR ATMOSPHERIC PARTICLES

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APPLIED OPTICS 1982年第16期21卷 3011-3020页

作者： CLARKE, AD []The author is with University of Washington Department of Civil Engineering Environmental Engineering Science Program Seattle Washington 98195.

A new technique has been developed for determination of optical depths δa as low as 0.0005 for thin layers of absorbing materials or particles. The measurement involves optical amplification of the absorption and is ... 详细信息

A new technique has been developed for determination of optical depths δ_a as low as 0.0005 for thin layers of absorbing materials or particles. The measurement involves optical amplification of the absorption and is not affected by the scattering properties of the absorber. This is accomplished by introducing the absorber into the virtually isotropic radiation field between two high-reflectance diffusing wafers and measuring the resultant attenuation of the transmitted light. The technique has been directed toward determination of the absorption coefficient of atmospheric aerosols in remote and relatively unpolluted locations. Provided appropriate collection filters and sampling conditions are used, the method can establish an absorption coefficient for the aerosol as low as 5 × 10^?9 m^?1 within a 10-h sampling period. A proportionally higher absorption coefficient requires proportionally less sample time. This paper discusses instrument design, the theoretical optical model, laboratory calibration, and a field test of the technique.

关键词： Absorption coefficient Atmospheric absorption Cloud effects Multiple scattering Optical depth Radiative transfer

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EFFECTS OF FILTER INTERNAL-REFLECTION COEFFICIENT ON LIGHT-ABSORPTION MEASUREMENTS MADE USING THE INTEGRATING PLATE METHOD

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APPLIED OPTICS 1982年第16期21卷 3021-3031页

作者： CLARKE, AD []The author is with University of Washington Department of Civil Engineering Environmental Engineering Science Program Seattle Washington 98195.

Optical properties of Nuclepore filter media, as used in the integrating plate (IP) method for determination of aerosol light absorption, have been examined. It has been shown that the internal reflectance is high for the Nuclepore filters typically used and that changes in this value result in spurious contributions to absorption measurements. It has been found that aerosol particles on the filter surface can substantially alter the internal reflection coefficient of this material for a wide variety of aerosol types. The amount and nature of this change are found to vary with optical and physical properties of the aerosol in contact with the filter surface. A simple mathematical model of the optical system is described that allows for variations in Nuclepore internal reflectance. Implications of this model and data suggest that light absorption measurements as determined via the IP method may be systematically overestimated for certain samples by as much as 30%. Estimates of the magnitude of this inaccuracy for a given IP absorption measurement are presented based on the model and supplementary back reflectance measurements.

关键词： Absorption coefficient Diffuse reflectance Multiple scattering Optical properties Particle scattering Reflection coefficient

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Hybrid membrane filtration process for leachate treatment

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WATER RESEARCH 1996年第11期30卷 2691-2706页

作者： Pirbazari, M Ravindran, V Badriyha, BN Kim, SH Environmental Engineering Program Department of Civil Engineering University of Southern California Los Angeles CA 90089-2531 U.S.A.

A hybrid technology known as the ultrafiltration-biologically active carbon (UF-BAC) process that amalgamates adsorption, biodegradation and membrane filtration is found to be highly efficient for treatment of landfill leachates. The process employs bioactive powdered activated carbon (PAC) with a leachate-acclimated microbial culture for the simultaneous sorption and biodegradation of organic constituents. Tubular cross-flow ultrafiltration membrane modules separate out colloids and microorganisms, and a high quality permeate is obtained. Batch biokinetic studies were performed for the two leachates to evaluate their extent of biodegradability and biodegradation kinetics. The process efficiencies for both leachates were in the range of 95-98% in terms of TOC removal, and exceeded 97% for specific organic pollutants. The UF-BAC process compared well with the PACT process in terms of organic removal, and produced higher quality effluent in terms of suspended solids (100% removal). The study demonstrated that addition of 1% PAC mitigated permeate flux deterioration attributed to membrane fouling and concentration polarization, and enhanced permeate transport. Possible mechanisms for flux amelioration are discussed. Copyright (C) 1996 Elsevier Science Ltd

关键词： hybrid membrane filtration ultrafiltration bioactive carbon biofilm landfill leachate membrane fouling concentration polarization permeate flux

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Axisymmetric alternating direction explicit scheme for efficient coupled simulation of hydro-mechanical interaction in geotechnical engineering-Application to circular footing and deep tunnel in saturated ground

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Journal of Rock Mechanics and Geotechnical engineering 2018年第2期10卷 259-279页

作者： Simon Heru Prassetyo Marte Gutierrez Department of Civil and Environmental Engineering Colorado School of MinesGoldenUSA Mining Engineering Program Institut Teknologi BandungBandungIndonesia

Explicit solution techniques have been widely used in geotechnical engineering for simulating the coupled hydro-mechanical(H-M) interaction of fluid flow and deformation induced by structures built above and under saturated ground, i.e. circular footing and deep tunnel. However, the technique is only conditionally stable and requires small time steps, portending its inefficiency for simulating large-scale H-M problems. To improve its efficiency, the unconditionally stable alternating direction explicit(ADE)scheme could be used to solve the flow problem. The standard ADE scheme, however, is only moderately accurate and is restricted to uniform grids and plane strain flow conditions. This paper aims to remove these drawbacks by developing a novel high-order ADE scheme capable of solving flow problems in nonuniform grids and under axisymmetric conditions. The new scheme is derived by performing a fourthorder finite difference(FD) approximation to the spatial derivatives of the axisymmetric fluid-diffusion equation in a non-uniform grid configuration. The implicit Crank-Nicolson technique is then applied to the resulting approximation, and the subsequent equation is split into two alternating direction sweeps,giving rise to a new axisymmetric ADE scheme. The pore pressure solutions from the new scheme are then sequentially coupled with an existing geomechanical simulator in the computer code fast Lagrangian analysis of continua(FLAC). This coupling procedure is called the sequentially-explicit coupling technique based on the fourth-order axisymmetric ADE scheme or SEA-4-AXI. Application of SEA-4-AXI for solving axisymmetric consolidation of a circular footing and of advancing tunnel in deep saturated ground shows that SEA-4-AXI reduces computer runtime up to 42%-50% that of FLAC’s basic scheme without numerical instability. In addition, it produces high numerical accuracy of the H-M solutions with average percentage difference of only 0.5%-1.8%.

关键词： Hydro-mechanical(H-M) interaction Explicit coupling technique Alternating direction explicit(ADE) scheme High-order finite difference(FD) Non-uniform grid Axisymmetric consolidation Circular footing Deep tunnel in saturated ground

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DEALING WITH NEAR COLLINEARITY IN CHEMICAL MASS BALANCE RECEPTOR MODELS

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ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS 1992年第5期26卷 933-938页

作者： HENRY, RC University of Southern California Civil Engineering Department Environmental Engineering Program Los Angeles CA 90089-2531 U.S.A.

The amount of airborne particulate pollution attributable to various sources can be estimated from a linear least squares (LLS) fit of concentrations of chemical elements observed at a receptor to the known elemental composition of the particles emitted by the sources. The resulting least squares problem often displays a high degree of ill-conditioning and associated inflation of the uncertainties in the estimates. Because of the physical constraints of the problem, variable selection and ridge regression cannot be used to remedy the ill-conditioning. In particular, it is shown that a stable ridge regression solution is equivalent to assuming sources of airborne particulates with negative elemental composition. A method is developed which defines, for a specific level of acceptable uncertainty, three classes of sources;those which can be estimated accurately by LLS, those which cannot be so estimated and those which cannot be accurately estimated individually but participate in linear combinations which can be accurately estimated. A technique is presented which determines those linear combinations of source contributions of minimum variance.

关键词： RECEPTOR MODELS AIRBORNE PARTICLES CHEMICAL MASS BALANCE NEAR COLLINEARITY REGRESSION

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IDENTIFICATION OF TRIHALOACETALDEHYDES IN OZONATED AND CHLORINATED FULVIC-ACID SOLUTIONS

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ANALYST 1993年第1期118卷 71-72页

作者： XIE, YF RECKHOW, DA Environmental Engineering Program Department of Civil Engineering University of Massachusetts Amherst MA 01003 United States

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.

关键词： MASS SPECTRA CHLORINATION OZONATION DISINFECTION BY-PRODUCTS TRIHALOACETALDEHYDES

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SOIL COLOR VARIATIONS ALONG AN IRON-OXIDE GRADIENT IN A MINE DRAINAGE TREATMENT WETLAND

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WETLANDS 1994年第3期14卷 243-246页

作者： TARUTIS, WJ UNZ, RF Program in Ecology and Department of Civil & Environmental Engineering The Pennsylvania State University University Park

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.

关键词： ACID MINE DRAINAGE CONSTRUCTED WETLANDS IRON OXIDES SOIL COLOR

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HYDRAULIC AND MECHANICAL CHARACTERISTICS OF A COMPACTED MUNICIPAL SOLID-WASTE COMPOST

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WASTE MANAGEMENT & RESEARCH 1993年第2期11卷 127-142页

作者： BENSON, CH OTHMAN, MA Environmental Geotechnics Program Department of Civil and Environmental Engineering University of Wisconsin-Madison Madison Wisconsin 53706 U.S.A.

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.

关键词： MUNICIPAL SOLID WASTE SLUDGE COMPOST CO-COMPOSTER HYDRAULIC CONDUCTIVITY PERMEABILITY LANDFILL COVER DESICCATION FREEZE THAW SLOPE STABILITY

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