bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation between Cloud-Seeding and Air-Pollution Effects
Authors: Givati Amir , Rosenfeld Daniel
Published: October 2005

Enhancement of precipitation by cloud-seeding operations has been reported in many studies around the world in the last several decades. On the other hand, suppression of rain and snow by urban and industrial air pollution recently has been documented and quantified. Here it is shown that the two effects are the opposite sides of the same coin, demonstrating the sensitivity of clouds to anthropogenic aerosols of different kinds. This is done by analyzing the rainfall amounts in northern Israel during the last 53 years and explaining the changes there as the combined opposite effects of precipitation suppression by air pollution and enhancement by glaciogenic cloud seeding. Time series based on precipitation from rain gauges were analyzed for seeded and nonseeded days and periods in the experimental control and the target areas. The response variable is Ro, the orographic enhancement factor, which is the ratio of gauge-measured rainfall in inland hilly areas (500–1000 m) to the rainfall at the upwind coasts and plains. The results show that for the whole period of 1950–2002 the Ro of the hilly areas decreased by 15%. In the early nonseeded period (1950–60) Ro was found to be higher than the nonseeded days of the following period, which was the randomized experimental period (1961–74). This result apparently shows the effect of the increasing pollution. Factor Ro had an identical decreasing trend during the seeded days of the experimental period and through the subsequent fully operationally seeded period (1975–2002). However, the trend line of Ro was shifted upward by 12%–14% for the seeded rain time series in comparison with the unseeded time series. Thus, the opposite effects of air pollution and seeding appear to have nearly canceled each other in recent years, leading to the false impression that cloud seeding is no longer effective. However, the findings here suggest that if the operational seeding were to stop, Ro would decrease further by about 12%–14%. The sensitivity of Ro to both seeding and pollution effects was greatest in the areas with the greatest natural orographic enhancement factor and was practically nonexistent in areas in which Ro is near unity. This result suggests that the orographic clouds are the most sensitive to air pollution as well as to cloud-seeding effects on clouds and precipitation, in agreement with the large susceptibility of precipitation from such short-living shallow clouds to aerosols. Based on previous studies and on the results of this paper, it is suggested that the proposed mechanism is the most likely explanation to the observations, and no alternative explanations such as long-term trends in the cross-mountain moisture flux were found probable. It is certain that additional research is required.
Generating Multiyear Gridded Daily Rainfall over New Zealand
Authors: Tait Andrew , Turner Richard
Published: October 2005

Daily rainfall totals are a key input for hydrological models that are designed to simulate water and pollutant flow through both soil and waterways. Within New Zealand there are large areas and many river catchments where no long-term rainfall observations exist. A method for estimating daily rainfall over the whole of New Zealand on a 5-km grid is described and tested over a period from January 1985 to April 2002. Improvement over a spatial interpolation method was gained by scaling high-elevation rainfall estimates using simulated mesoscale model rainfall surfaces that are generated for short periods in 1994 and 1996. This method is judged to produce reasonable and useful estimates of daily rainfall.
Retrieval of Microscale Wind and Temperature Fields from Single- and Dual-Doppler Lidar Data
Authors: Newsom Rob K. , Ligon David , Calhoun Ron , Heap Rob , Cregan Edward , Princevac Marko
Published: October 2005

Dual-Doppler lidar observations are used to assess the accuracy of single-Doppler retrievals of microscale wind and temperature fields in a shear-driven convective boundary layer. The retrieval algorithm, which is based on four-dimensional variational data assimilation, is applied by using dual- and single-Doppler lidar data that are acquired during the Joint Urban 2003 field experiment. The velocity field that was retrieved using single-Doppler data is compared directly with radial velocities that were measured by a second noncollocated lidar. Dual-Doppler retrievals are also performed and then compared with the single-Doppler retrieval. The linear correlation coefficient and rms deviation between the single-Doppler retrieval and the observations from the second lidar are found to be 0.94 and 1.2 m s−1, respectively. The high correlation is mainly the result of good agreement in the mean vertical structure as observed by the two lidars. Comparisons between the single- and dual-Doppler retrieval indicate that the single-Doppler retrieval underestimates the magnitude of fluctuations in the crossbeam direction. Vertical profiles of horizontally averaged correlations between the single- and dual-Doppler retrievals also show a marginal correlation (0.4–0.8) between one of the horizontal velocity components. Again, this suggests that the retrieval algorithm has difficulty estimating the crossbeam component from single-Doppler data.
An Integrated Turbulence Scheme for Boundary Layers with Shallow Cumulus Applied to Pollutant Transport
Authors: Angevine Wayne M.
Published: October 2005

A scheme is described that provides an integrated description of turbulent transport in free convective boundary layers with shallow cumulus. The scheme uses a mass-flux formulation, as is commonly found in cumulus schemes, and a 1.5-order closure, involving turbulent kinetic energy and eddy diffusivity. Both components are active in both the subcloud and cloud layers. The scheme is called “mass flux–diffusion.” In the subcloud layer, the mass-flux component provides nonlocal transport. The scheme combines elements from schemes that are conceptually similar but differ in detail. An entraining plume model is used to find the mass flux. The mass flux is continuous through the cloud base. The lateral fractional entrainment rate is constant with height, while the detrainment-rate profile reduces the mass flux smoothly to zero at the cloud top. The eddy diffusivity comes from a turbulent kinetic energy–length scale formulation. The scheme has been implemented in a simple one-dimensional (single column) model. Results of simulations of a standard case that has been used for other model intercomparisons [Atmospheric Radiation Measurement (ARM), 21 June 1997] are shown and indicate that the scheme provides good results. The model also simulates the profile of a conserved scalar; this capability is applied to a case from the 1999 Southern Oxidants Study Nashville (Tennessee) experiment, where it produces good simulations of vertical profiles of carbon monoxide in a cloud-topped boundary layer.
A New Empirical Model of the Temperature–Humidity Index
Authors: Schoen Carl
Published: October 2005

A simplified scale of apparent temperature, considering only dry-bulb temperature and humidity, has become known as the temperature–humidity index (THI). The index was empirically constructed and was presented in the form of a table. It is often useful to have a formula instead for use in interpolation or for programming calculators or computers. The National Weather Service uses a polynomial multiple regression formula, but it is in some ways unsatisfactory. A new model of the THI is presented that is much simpler—having only 3 parameters as compared with 16 for the NWS model. The new model also more closely fits the tabulated values and has the advantage that it allows extrapolation outside of the temperature range of the table. Temperature–humidity pairs above the effective range of the NWS model are occasionally encountered, and the ability to extrapolate into colder temperature ranges allows the new model to be more effectively contained as part of a more general apparent temperature index.
A Proposed Solution to the Range–Doppler Dilemma of Weather Radar Measurements by Using the SMPRF Codes, Practical Results, and a Comparison with Operational Measurements
Authors: Pirttilä Juha , Lehtinen Markku S. , Huuskonen Asko , Markkanen Markku
Published: October 2005

Based on the measurement principles used on incoherent scatter radars, the authors have developed the Simultaneous Multiple Pulse Repetition Frequency (SMPRF) code that is intended to solve the range–Doppler dilemma and that can be used with modern magnetron radars. The working principle of the code is explained in mathematical terms and with the help of a simplified model. Results from the SMPRF and traditional fixed PRF weather radar measurements are compared, and the reasons for the differences are explained. The practical results show that the SMPRF code seems to work in the manner that is predicted by the theoretical and model calculations. The SMPRF code provides enough information to produce a high-resolution measured spectrum for each range gate. The shape of these measured spectra are seldom purely Gaussian. It is possible that more advanced raw products, other than just reflectivity, velocity, and width, can be produced with the help of these high-resolution spectra.
Validation of a Physical Retrieval Scheme of Solar Surface Irradiances from Narrowband Satellite Radiances
Authors: Deneke H. , Feijt A. , van Lammeren A. , Simmer C.
Published: October 2005

An algorithm is presented to derive the downwelling solar surface irradiance from satellite measurements of the 0.63-μm reflectance, which explicitly accounts for variations in cloud optical depth and integrated water vapor. For validation, a long-term dataset of 40 356 pyranometer measurements and 1450 NOAA-14 Advanced Very High Resolution Radiometer (AVHRR) satellite scenes of the Netherlands is used. A mean overestimate of the satellite-retrieved irradiance by 7% is found, which is consistent with numerous other studies reporting positive biases of atmospheric transmissivities that are calculated by radiative transfer schemes in comparison with measurements. The bias can be explained by the calibration and measurement uncertainties of both the AVHRR and pyranometer. A strong solar zenith angle dependence of the bias is found when water clouds are assumed in the retrieval. Such a dependence is not observed for ice clouds. Currently, there is not enough information for a conclusive explanation of this behavior. Comparing individual pyranometer measurements at 30 stations within a region of about 150 km2 averaged over 40 min, a large rmse of 86 W m−2 is found. If the average of all of the stations for a satellite overpass is considered instead, a much better accuracy is achieved (rmse of 33 W m−2). For monthly averages of all of the stations, the rmse is further reduced to 12 W m−2. Evidence is presented that suggests that a significant fraction of the rmse in the comparison originates from the variability of the irradiance field, which limits the representativeness of the reference ground-based pyranometer measurements for the satellite-retrieved values.
Developing Clear-Sky Flux Products for the Geostationary Earth Radiation Budget Experiment
Authors: Futyan J. M. , Russell J. E.
Published: October 2005

This paper describes the planned processing of monthly mean and monthly mean diurnal cycle flux products for the Geostationary Earth Radiation Budget (GERB) experiment. The use of higher-spatial-resolution flux estimates based on multichannel narrowband imager data to improve clear-sky sampling is investigated. Significant improvements in temporal sampling are found, leading to reduced temporal sampling errors and less dependence on diurnal models for the monthly mean products. The reduction in temporal sampling errors is found to outweigh any spatial sampling errors that are introduced. The resulting flux estimates are used to develop an improved version of the half-sine model that is used for the diurnal interpolation of clear-sky longwave fluxes over land in the Earth Radiation Budget Experiment (ERBE) and Clouds and the Earth’s Radiant Energy System (CERES) missions. Maximum outgoing longwave radiation occurs from 45 min to 1.5 h after local noon for most of the GERB field of view. Use of the ERBE half-sine model for interpolation therefore results in significant distortion of the diurnal cycle shape. The model that is proposed here provides a well-constrained fit to the true diurnal shape, even for limited clear-sky sampling, making it suitable for use in the processing of both GERB and CERES second-generation monthly mean clear-sky data products.
Sensitivity of MM5-Simulated Boundary Layer Characteristics to Turbulence Parameterizations
Authors: Berg Larry K. , Zhong Shiyuan
Published: October 2005

The sensitivity of high-resolution mesoscale simulations to boundary layer turbulence parameterizations is investigated using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) and observations from two field campaigns. Three widely used turbulence parameterizations were selected for evaluation, two of which [Blackadar (BK) and Medium Range Forecast (MRF) schemes] are simple first-order nonlocal schemes and one [Gayno–Seaman (GS) scheme] of which is a more complex 1.5-order local scheme that solves a prognostic equation for turbulence kinetic energy (TKE). The two datasets are the summer 1996 Boundary Layer Experiment (BLX96) in the southern Great Plains and the autumn 2000 Vertical Transport and Mixing (VTMX) field campaign in the Salt Lake Valley in Utah. Comparisons are made between observed and simulated mean variables and turbulence statistics. Despite the differences in their complexity, all three schemes show similar skill predicting near-surface and boundary layer mean temperature, humidity, and winds at both locations. The BK and MRF schemes produced daytime boundary layers that are more mixed than those produced by the GS scheme. The mixed-layer depths are generally overestimated by the MRF scheme, underestimated by the GS scheme, and well estimated by the BK scheme. All of the schemes predicted surface latent heat fluxes that agreed reasonably well with the observed values, but they substantially overestimated surface sensible heat fluxes because of a significant overprediction of net radiation. In addition, each parameterization overestimated the sensible and latent heat flux aloft. The results suggest that there is little gain in the overall accuracy of forecasts with increasing complexity of turbulence parameterizations.
Treatment of Anterior Cruciate Ligament Injuries, Part 2
Authors: Beynnon Bruce D. , Johnson Robert J. , Abate Joseph A. , Fleming Braden C. , Nichols Claude E.
Published: October 2005

Anterior cruciate ligament tears, common among athletes, are functionally disabling; they predispose the knee to subsequent injuries and the early onset of osteoarthritis. A total of 3810 studies published between January 1994 and the present were identified and reviewed to determine the current state of knowledge regarding the treatment of anterior cruciate ligament injuries. Part 1 of this article focused on studies pertaining to the biomechanical behavior of the anterior cruciate ligament, the prevalence of and risk factors for injuries related to it, the natural history of the ligament-deficient knee, injuries associated with anterior cruciate ligament disruption, indications for the treatment of anterior cruciate ligament injuries, as well as nonoperative and operative treatments. Part 2 includes technical aspects of anterior cruciate ligament surgery, bone tunnel widening, graft healing, rehabilitation after anterior cruciate ligament reconstruction, and the effects of sex, age, and activity level on the outcome of such reconstructive surgery.
LIN-12/Notch trafficking and regulation of DSL ligand activity during vulval induction inCaenorhabditis elegans
Authors: Shaye Daniel D. , Greenwald Iva
Published: October 2005

A novel mode of crosstalk between the EGFR-Ras-MAPK and LIN-12/Notch pathways occurs during the patterning of a row of vulval precursor cells(VPCs) in Caenorhabditis elegans: activation of the EGFR-Ras-MAPK pathway in the central VPC promotes endocytosis and degradation of LIN-12 protein. LIN-12 downregulation in the central VPC is a prerequisite for the activity of the lateral signal, which activates LIN-12 in neighboring VPCs. Here we characterize cis-acting targeting sequences in the LIN-12 intracellular domain and find that in addition to a di-leucine motif,serine/threonine residues are important for internalization and lysine residues are important for post-internalization trafficking and degradation. We also identify two trans-acting factors that are required for post-internalization trafficking and degradation: ALX-1, a homolog of yeast Bro1p and mammalian Alix and the WWP-1/Su(dx)/Itch ubiquitin ligase. By examining the effects of mutated forms of LIN-12 and reduced wwp-1or alx-1 activity on subcellular localization and activity of LIN-12,we provide evidence that the lateral signal-inhibiting activity of LIN-12 resides in the extracellular domain and occurs at the apical surface of the VPCs.
Hydrothermal Synthesis and Photocatalytic Property of 2-Dimensional Bismuth Molybdate Nanoplates
Authors: Yu Jianqiang , Kudo Akihiko
Published: October 2005

Bi2MoO6 nanoplates with an Aurivillius structure and a uniform thickness of 15–30 nm were fabricated by a hydrothermal process at 413 K for 48 h with the assistance of the surfactant cetyltrimethylammonium bromide (CTAB). The nanoplate structure was favorable to the photocatalytic O2-evolution performance under visible light irradiation.
Water-soluble Poly(3,4-ethylenedioxythiophene) Nanocomposites Created by a Templating Effect of β-1,3-Glucan Schizophyllan
Authors: Li Chun , Numata Munenori , Hasegawa Teruaki , Fujisawa Tomohisa , Haraguchi Shuichi , Sakurai Kazuo , Shinkai Seiji
Published: October 2005

Chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of single-chain schizophyllan (s-SPG) gave water-soluble nanocomposites with the very uniform globular structure. The findings indicate that s-SPG is capable of acting not only as a one-dimensional host to create fibrous architectures but also as a neutral host to create nanoparticles. The mechanism is reasonably explained by the difference in the hydrophobicity of guest polymers or assemblies.
Assured Structural Identification of the Spin Adducts Generated from the Nitrone Spin Traps by ESR, MASS, and HPLC Analyses
Authors: Fuji Tomoki , Yuzuri Tomoaki , Sakakibara Kazuhisa
Published: October 2005

Structural identification of the spin adducts produced by α-phenyl-N-tert-butylnitrone (PBN) with short-lived carbon centered radicals (phenyl, n-butyl, and tert-butyl) can be carried out unambiguously by combining the data obtained with ESR, Mass, and HPLC analyses.
Photopolymerization of Acrylamide Derivatives in Polyelectrolyte Microcapsules
Authors: Lu Zonghuan , Shutava Tatsiana , Sahiner Nurettin , John Vijay , Lvov Yuri
Published: October 2005

Multilayered polyelectrolyte poly(sodium 4-styrenesulfonate)/poly(allylamine hydrochloride) microcapsules prepared using layer-by-layer (LbL) assembly technology were filled by UV-photopolymerization of acrylamide derivatives directly into the capsule interior. Influences of component properties and polymerization conditions on the structure of the obtained composites are discussed. Mixing formed polymer chains with the capsule wall material stabilizes the initial wall conformation and lowers capsule sensitivity to environmental conditions.
Synthesis and Structures of the First Titanium(IV) Complexes with Cyclic Tetrasiloxide Ligands: Incomplete and Complete Cage Titanosiloxanes
Authors: Hirotsu Masakazu , Taruno Shinsuke , Yoshimura Takashi , Ueno Keiji , Unno Masafumi , Matsumoto Hideyuki
Published: October 2005

The first titanium(IV) complexes with cyclic tetrasiloxide ligands, [Ti(L1H)(OSiMe3)]2(H2O) (1) and (CpTiCl)4(L2)2 (2), were synthesized using the all-cis isomer of cyclotetrasiloxanetetraols R4(SiO)4(OH)4 (L1H4: R = Ph, L2H4: R = iPr) as ligand precursors. X-ray analysis revealed that 1 is a dinuclear complex with bridging siloxy and aqua ligands while 2 has a tetranuclear cage structure capped by two L2 ligands.
A Novel Molecular Structure of a Ferrocene Derivative Containing Mesogenic Group, 1,1′-Bis[2-[4-(4-methoxyphenoxycarbonyl)phenoxy]ethoxycarbonyl]ferrocene
Authors: Nakamura Naotake , Nishikawa Masako
Published: October 2005

The molecular and crystal structures of 1,1′-disubstituted ferrocene derivative, 1,1′-bis[2-[4-(4-methoxyphenoxycarbonyl)phenoxy]ethoxycarbonyl]ferrocene (bMAF-2) were determined by X-ray diffraction method using the single crystals. The trans conformation (novel “Z” shape) in which the two substituents existed in the opposite directions was found out newly. The structure was different from the cis conformation (“U” shape) and the trans conformation (“S” shape) reported already. It may be one of the most important reasons why bMAF-2 (“Z” shape) shows no liquid crystallinity that the ratio of the width to length is rather large compared with those of other liquid crystalline homologues (“U” shape and “S” shape).
Porous Carbons from Octafluoronaphthalene by Chemical Reaction and Heat-treatment
Authors: Yamada Yoshio , Ohno Hiroyuki , Tanaike Osamu , Hatori Hiroaki
Published: October 2005

Porous carbons were obtained from octafluoronaphthalene defluorinated with sodium metal. When the by-product, NaF was removed with acid solution and the product was treated at 1073 K, the carbon gave a high surface area with mesopores as well as micropores. The coexistence of NaF during heat-treatment of the defluorinated product, however, brought about the formation of pores with a squarish shape.
Crystal Structure of Light-induced Colored Species from Photochromic Dimer of 1,4-Bis(imidazolyl)tetrafluorobenzene
Authors: Kikuchi Azusa , Abe Jiro
Published: October 2005

On irradiation with UV light, the photochromic dimer of 1,4-bis(imidazolyl)tetrafluorobenzene produced the colored transient species in solution and solid. Though the dimerization reaction to form the photochromic dimer prevents the isolation and characterization of the colored species at room temperature, the single crystals of the colored species could be successfully obtained from the light-irradiated toluene solution of the dimer at 200 K, and the molecular structure of the colored species is unambiguously determined by the X-ray diffraction analysis.
Highly Efficient Synthesis of Oligo-N-acetylglucosamines by Iterative Glycosylation of Di- and Tetrachlorophthaloyl-protected Thioglucosamines
Authors: Yamada Takeshi , Kinjyo Shigemori , Yoshida Jun-ichi , Yamago Shigeru
Published: October 2005

The iterative glycosylation of di- and tetrachlorophthaloyl-protected thioglucosamines, which act as both glycosyl donors and acceptors, gives the corresponding protected oligoglucosamines. Subsequent removal of the protecting groups followed by acetylation of the free amines affords oligo-N-acetylglucosamines in good to excellent combined yields.
Vanadate as a Futile, Superoxide Ion-producing Substrate of Trypanothione Reductase from Trypanosoma cruzi
Authors: Khan Mohammed Omar Faruk , Parveen Seheli , Seddon Gavin Malcolm , Douglas Kenneth Thomas
Published: October 2005

Recombinant Trypanosoma cruzi trypanothione reductase can oxidize NADPH in a futile cycle in the presence of vanadate ion as a result of the generation of reactive oxygen and other radical species from the active site dithiol and the NADPH. This process is inhibited by competitive inhibitors of trypanothione reductase catalyzed reduction of trypanothione disulfide.
Challenges in Biodegradation of Trace Organic Contaminants—Gasoline Oxygenates and Sex Hormones
Authors: Suidan M. T. , Esperanza M. , Zein M. , McCauley P. , Brenner R. C. , Venosa A. D.
Published: October 2005

Advances in analytical methods have led to the identification of several classes of organic chemicals that are associated with adverse environmental effects. Two such classes of organic chemicals, gasoline oxygenates and sex hormones, are used to illustrate challenges associated with the biodegradation of trace organic contaminants. Gasoline oxygenates can be present in groundwater, alone, or commingled with xylene, at appreciable concentrations. However, target‐treated water standards dictate that gasoline oxygenates be reduced to the microgram‐per‐liter concentration range before consumption. Sex hormones, on the other hand, are present in wastewater matrixes in the part‐per‐trillion concentration range, and the biggest challenge that must be met, before optimizing their removal, is facilitating their detection.
The Fate of Estrogenic Hormones in an Engineered Treatment Wetland with Dense Macrophytes
Authors: Gray James L. , Sedlak David L.
Published: October 2005

Recently, the estrogenic hormones 17β‐estradiol (E2) and 17α‐ethinyl estradiol (EE2) have been detected in municipal wastewater effluent and surface waters at concentrations sufficient to cause feminization of male fish. To evaluate the fate of steroid hormones in an engineered treatment wetland, lithium chloride, E2, and EE2 were added to a treatment wetland test cell. Comparison of hormone and tracer data indicated that 36% of the E2 and 41% of the EE2 were removed during the cell's 84‐h hydraulic retention time (HRT). The observed attenuation was most likely the result of sorption to hydrophobic surfaces in the wetland coupled with biotransformation. Sorption was indicated by the retardation of the hormones relative to the conservative tracer. Biotransformation was indicated by elevated concentrations of the E2 metabolite, estrone. It may be possible to improve the removal efficiency by increasing the HRT or the density of plant materials.
Rejection of Emerging Organic Micropollutants in Nanofiltration–Reverse Osmosis Membrane Applications
Authors: Xu Pei , Drewes Jörg E. , Bellona Christopher , Amy Gary , Kim Tae‐Uk , Adam Marc , Heberer Thomas
Published: October 2005

The rejection of emerging trace organics by a variety of commercial reverse osmosis (RO), nanofiltration (NF), and ultra‐low‐pressure RO (ULPRO) membranes was investigated using TFC‐HR, NF‐90, NF‐200, TFC‐SR2, and XLE spiral membrane elements (Koch Membrane Systems, Wilmington, Massachusetts) to simulate operational conditions for drinking‐water treatment and wastewater reclamation. In general, the presence of effluent organic matter (EfOM) improved the rejection of ionic organics by tight NF and RO membranes, as compared to a type‐II water matrix (adjusted by ionic strength and hardness), likely as a result of a decreased negatively charged membrane surface. Rejection of ionic pharmaceutical residues and pesticides exceeded 95% by NF‐90, XLE, and TFC‐HR membranes and was above 89% for the NF‐200 membrane. Hydrophobic nonionic compounds, such as bromoform and chloroform, exhibited a high initial rejection, as a result of both hydrophobic–hydrophobic solute‐membrane interactions and steric exclusion, but rejection decreased significantly after 10 hours of operation because of partitioning of solutes through the membranes. This resulted in a partial removal of disinfection byproducts by the RO membrane TFC‐HR. In a type‐II water matrix, the effect of increasing feed water recoveries on rejection of hydrophilic ionic and nonionic compounds was compound‐dependent and not consistent for different membranes. The presence of EfOM, however, could neutralize the effect of hydrodynamic operating condition on rejection performance. The ULPRO and tight NF membranes were operated at lower feed pressure, as compared to the TFC‐HR, and provided a product water quality similar to a conventional RO membrane, regarding trace organics of interest.
Presence of Macrolide‐Lincosamide‐Streptogramin B and Tetracycline Antimicrobials in Swine Waste Treatment Processes and Amended Soil
Authors: Zilles Julie , Shimada Toshio , Jindal Archana , Robert Matt , Raskin Lutgarde
Published: October 2005

Little is known about the fate of antimicrobials during common agricultural waste handling procedures. To better define the potential scope of this problem, concentrations of antimicrobials throughout the waste treatment process were estimated based on known antimicrobial usage, and the resulting predictions of high antimicrobial concentrations indicated the need for further investigation. Samples from building pits, a solids settling basin, a holding pond, and soil amended with waste treatment byproducts were therefore analyzed for traditional chemical parameters and macrolide, lincosamide, and tetracycline antimicrobials. Substantial improvements in water quality were observed during the treatment process. While the macrolide tylosin was not detected, chlortetracycline, oxytetracycline, and lincomycin were found at high concentrations throughout the waste treatment process. Oxytetracycline and lincomycin were also detected in soil from a field amended with waste treatment byproducts.
The Fate and Removal of Triclosan during Wastewater Treatment
Authors: Thompson A. , Griffin P. , Stuetz R. , Cartmell E.
Published: October 2005

This work examines the variation in removal efficiency of triclosan in wastewater treatment works in the United Kingdom between November 2003 and April 2004. Concentrations of triclosan were measured at set points within three different types of wastewater treatment works: rotating biological contactors, trickling filters, and activated sludge. Overall removal of triclosan through these plants ranged from 58 to 96% (rotating biological contactors), 86 to 97% (trickling filter), and 95 to 98% (activated sludge).
Legal Aspects and Technical Alternatives for the Treatment of Reservoir Brines at the Activo Luna Oilfield, Mexico
Authors: Birkle Peter , Cid Vázquez Adolfo L. , Fong Aguilar J. L.
Published: October 2005

Deep formation water, extracted as an undesired byproduct from on‐shore production wells at the Activo Luna oilfield and processed in adjacent oil fields, are highly enriched in salt minerals, especially in sodium chloride (NaCl) (262 000 mg/L), but also in metals and nonmetals, such as strontium (Sr) (2068 mg/L), bromine (Br) (2034 mg/L), boron (B) (396 mg/L), iodine (I) (43.4 mg/L), selenium (Se) (3.74 mg/L), and arsenic (As) (0.55 mg/L). Direct reinjection of the brine underground is not possible because of elevated pressure conditions within the petroleum reservoir. The disposal into near shore areas of the Gulf of Mexico without treatment must be rejected because of a) elevated concentrations of some toxic elements, such as B, silver (Ag), thallium (Tl), Se and cadmium (Cd), which exceed permissible limits of environmental legislation for surface discharge (Official Mexican norms NOM‐001‐ECOL‐1998 and CE‐CCA‐001/89), and b) differences in density that could cause the descent of hypersaline fluid to the ocean floor, potentially affecting the diversity and survival of the benthic ecosystem. Conventional treatment techniques, such as microfiltration or reverse osmosis, are not suitable for the Activo Luna brines because of their extreme mineralization, which will cause pressure conditions exceeding 200 bars across the membrane. As an alternative process, the evaporation of the entire brine volume of approximately 200 m3/day by solar ponds or industrial crystallization plants is suggested. The residual precipitated residuals are composed mainly of chlorine (Cl) (9460 tons/year), sodium (Na) (4230 tons/year), calcium (Ca) (1028 tons/year), potassium (K) (207 tons/year), and magnesium (Mg) (65.8 tons/year). As an alternative to its disposal on a dumpsite, some special minerals (especially NaCl, Mg, Sr, and Br) could be recovered for its economic value.
Performance Comparison of Structural Stormwater Best Management Practices
Authors: Barrett Michael E.
Published: October 2005

This paper describes a method for comparing the pollutant removal of a number of structural stormwater treatment devices, commonly referred to as best management practices (BMPs). Historically, the pollutant removal ability of a BMP has been expressed as a percent reduction in concentration or load. Unfortunately, the calculated percent reduction in pollutant concentration is strongly affected by the influent concentration, with the calculated reduction generally being much lower when the event mean concentrations (EMCs) in the untreated runoff from the test watershed are low. The objective of the proposed methodology is to eliminate this problem by predicting BMP performance for an arbitrary influent concentration, so that BMPs evaluated in different watersheds can be compared as if the influent quality at all sites were the same. This method allows BMPs to be compared based on the quality of effluent produced and the mass reduction. The proposed method uses linear regression as the primary tool to compute the expected effluent concentration from a BMP, given a specific influent concentration of interest and was developed using data collected in the California Department of Transportation BMP Retrofit Pilot Program. This technique reveals that for media filters, the concentration of sediment and other particle‐associated pollutants in treated runoff is generally unrelated to influent quality and is relatively constant. Wet basins with large permanent pool volumes also have effluent concentrations that are constant for most constituents and unrelated to influent concentrations. In these situations, the “percent reduction” in a pollutant EMC is not an inherent characteristic of the BMP, but a function of the influent EMC, because the quality of effluent produced is constant. Predicting the effluent quality of several types of conventional BMPs based on a common influent concentration allows an objective comparison of their performance and the selection of a BMP that addresses specific constituents of concern.
Optimization of Enhanced Biological Phosphorus Removal after Periods of Low Loading
Authors: Miyake Haruo , Morgenroth Eberhard
Published: October 2005

Enhanced biological phosphorus removal is a well‐established technology for the treatment of municipal wastewater. However, increased effluent phosphorus concentrations have been reported after periods (days) of low organic loading. The purpose of this study was to evaluate different operating strategies to prevent discharge of effluent after such low‐loading periods. Mechanisms leading to these operational problems have been related to the reduction of polyphosphate‐accumulating organisms (PAOs) and their storage compounds (polyhydroxy alkanoates [PHA]). Increased effluent phosphorus concentrations can be the result of an imbalance between influent loading and PAOs in the system and an imbalance between phosphorus release and uptake rates. The following operating conditions were tested in their ability to prevent a reduction of PHA and of overall biomass during low organic loading conditions: (a) unchanged operation, (b) reduced aeration time, (c) reduced sludge wastage, and (d) combination of reduced aeration time and reduced sludge wastage. Experiments were performed in a laboratory‐scale anaerobic–aerobic sequencing batch reactor, using acetate as the carbon source. Without operational adjustments, phosphorus‐release rates decreased during low‐loading periods but recovered rapidly. Phosphorus‐uptake rates also decreased, and the recovery typically required several days to increase to normal levels. The combination of reduced aeration time and reduced sludge wastage allowed the maintenance of constant levels of both PHA and overall biomass. A mathematical model was used to explain the influence of the tested operating conditions on PAO and PHA concentrations. While experimental results were in general agreement with model predictions, the kinetic expression for phosphorus uptake deviated significantly for the first 24 hours after low‐loading conditions. Mechanisms leading to these deviations need to be further investigated.
Development of a Gravity‐Independent Wastewater Bioprocessor for Advanced Life Support in Space
Authors: Nashashibi‐Rabah Majda , Christodoulatos Christos , Korfiatis George P.
Published: October 2005

Operation of aerobic biological reactors in space is controlled by a number of challenging constraints, mainly stemming from mass transfer limitations and phase separation. Immobilized‐cell packed‐bed bioreactors, specially designed to function in the absence of gravity, offer a viable solution for the treatment of gray water generated in space stations and spacecrafts. A novel gravity‐independent wastewater biological processor, capable of carbon oxidation and nitrification of high‐strength aqueous waste streams, is presented. The system, consisting of a fully saturated pressurized packed bed and a membrane oxygenation module attached to an external recirculation loop, operated continuously for over one year. The system attained high carbon oxidation efficiencies often exceeding 90% and ammonia oxidation reaching approximately 60%. The oxygen supply module relies on hydrophobic, nonporous, oxygen selective membranes, in a shell and tube configuration, for transferring oxygen to the packed bed, while keeping the gaseous and liquid phases separated. This reactor configuration and operating mode render the system gravity‐independent and suitable for space applications.
Field Demonstration of the Combined Effects of Absorption and Evapotranspiration on Septic System Drainfield Capacity
Authors: Rainwater Ken , Jackson Andrew , Ingram Wesley , Lee Chang Yong , Thompson David , Mollhagen Tony , Ramsey Heyward , Urban Lloyd
Published: October 2005

Drainfields for disposal of septic tank effluents are typically designed by considering the loss of water by either upward evapotranspiration into the atmosphere or lateral and downward absorption into the adjacent soil. While this approach is appropriate for evapotranspiration systems, absorption systems allow water loss by both mechanisms. It was proposed that, in areas where high evapotranspiration rates coincide with permeable soils, drainfield sizes could be substantially reduced by accounting for both mechanisms. A two‐year field demonstration was conducted to determine appropriate design criteria for areas typical of the Texas High Plains. The study consisted of evaluating the long‐term acceptance rates for three different drainfield configurations: evapotranspiration only, absorption only, and combined conditions. A second field demonstration repeated the experiments for additional observation of the combined evapotranspiration and absorption and achieved similar results as the first study. The field tests indicated that the current design loading criteria may be increased by at least a factor of two for the Texas High Plains region and other Texas areas with similar soil composition and evapotranspiration rates, while still retaining a factor of safety of two.
Evaluation of Membrane Bioreactor Process Capabilities to Meet Stringent Effluent Nutrient Discharge Requirements
Authors: Fleischer Edwin J. , Broderick Thomas A. , Daigger Glen T. , Fonseca Anabela D. , Holbrook R. David , Murthy Sudhir N.
Published: October 2005

A six‐stage membrane bioreactor (MBR) pilot plant was operated to determine and demonstrate the capability of this process to produce a low‐nutrient effluent, consistent with the nutrient reduction goals for the Chesapeake Bay. Biological nitrogen removal was accomplished using a multistage configuration with an initial anoxic zone (using the carbon in the influent wastewater), an aerobic zone (where nitrification occurred), a downstream anoxic zone (where methanol was added as a carbon source), and the aerated submerged membrane zone. The capability to reliably reduce effluent total nitrogen to less than 3 mg/L as nitrogen (N) was demonstrated. A combination of biological (using an initial anaerobic zone) and chemical (using alum) phosphorus removal was used to achieve effluent total phosphate concentrations reliably less than 0.1 mg/L as phosphorus (P) and as low as 0.03 mg/L as P. Alum addition also appeared to enhance the filtration characteristics of the MBR sludge and to reduce membrane fouling. Aeration of the submerged membranes results in thickened sludge with a high dissolved oxygen concentration (approaching saturation), which can be recycled to the main aeration zone rather than to an anoxic or anaerobic zone to optimize biological nutrient removal. Biological nutrient removal was characterized using the International Water Association Activated Sludge Model No. 2d. The stoichiometry of chemical phosphorus removal was also consistent with conventional theory and experience. The characteristics of the solids produced in the MBR were compared with those of a parallel full‐scale conventional biological nitrogen removal process and were generally found to be similar. These results provide valuable insight to the design and operating characteristics of MBRs intended to produce effluents with very low nutrient concentrations.
Specific Resistance to Filtration of Biomass from Membrane Bioreactor Reactor and Activated Sludge: Effects of Exocellular Polymeric Substances and Dispersed Microorganisms
Authors: Ng How Y. , Hermanowicz Slawomir W.
Published: October 2005

This study investigates the effect of dispersed microorganisms and exocellular polymeric substances on biomass dewaterability. Specific resistance to filtration (SRF) was measured for biomass from a membrane bioreactor and a completely mixed activated sludge system. Both laboratory‐scale reactors were fed with synthetic wastewater and operated at a high food‐to‐microorganism ratio (F/M) (1 to 11 kilograms chemical oxygen demand per kilogram mixed liquor volatile suspended solids per day [kgCOD/(kg MLVSS·d)]) and short solids retention times (0.25 to 5 d). The SRF values were affected by strong interactions of three parameters: (1) the mixed liquor suspended solids concentration, (2) the amount of dispersed microorganisms, and (3) the exocellular polymeric substances (EPS) concentration. At F/M smaller than 2 kg COD/(kg MLSS·d) and mixed liquor suspended solids (MLSS) concentration higher than 2000 mg/L, increasing amount of dispersed microorganisms in the biomass yielded higher SRF values. However, at high F/M (>5 kg COD/kg MLSS·d) and low MLSS concentrations (<600 mg/L), lower EPS concentrations resulted in slightly smaller SRF values, even though the amount of dispersed microorganisms in the biomass was much higher. Thus, at low MLSS concentrations, EPS concentrations rather than the amount of dispersed microorganisms tend to control SRF.
A Strategy for Controlling Deposition of Struvite in Municipal Wastewater Treatment Plants
Authors: Wu Qingzhong , Bishop Paul L. , Keener Tim C.
Published: October 2005

This paper presents strategies to reduce the risk of struvite deposition by controlling its location of formation. Two technical routes were investigated: (1) to fix the phosphate into the dewatered sludge cake, and (2) to remove phosphate from centrate or filtrate. Chemicals used include magnesium hydroxide [Mg(OH)2], both of reagent grade and reclaimed from a flue gas desulfurization system, magnesium chloride (MgCl2), calcium hydroxide [Ca(OH)2], ferric chloride (FeCl3) and aluminum sulfate [Al2(SO4)3]. Research results indicate that (1) for anaerobically well‐digested sludge, Mg(OH)2 is effective in fixing phosphate into sludge cake and improving sludge dewaterability, and (2) adding Mg(OH)2 into a reactor, located between the sludge dewatering facilities and the centrate or filtrate discharge line, and using air for mixing and carbon dioxide stripping, proves feasible in reducing struvite deposition in centrate or filtrate discharge lines and can generate a potentially valuable plant fertilizer—struvite.
Utility of Stormwater Monitoring
Authors: Lee Haejin , Stenstrom Michael K.
Published: October 2005

Stormwater runoff is now a major contributor to the pollution of coastal waters in the United States. Public agencies are responding by requiring stormwater monitoring to satisfy the National Pollutant Discharge Elimination System stormwater permit. However, studies to understand the utility of the current programs or to improve their usefulness have not yet been performed. In this paper, we evaluate the land‐use‐based program, the industrial stormwater permit program, and beach water‐quality monitoring in the County of Los Angeles, California, to determine if the results will be helpful to planners and regulators in abating stormwater pollution. The utility of the program has been assessed based on the programs' ability to accurately estimate the emissions for different classes of land use. The land‐use program appears successful, while the industrial monitoring program does not. Beach water‐quality monitoring suffers from a lack of real‐time monitoring techniques. We also provide suggested improvements, such as sampling method and time, and parameter selection.
Optimization of the Intermittent Aeration in a Full‐Scale Wastewater Treatment Plant Biological Reactor for Nitrogen Removal
Authors: Habermeyer Patrícia , Sánchez Antoni
Published: October 2005

The optimization of the intermittent aeration in a full‐scale biological reactor treating municipal and industrial wastewater has been studied by means of an experimental design, where the main factors considered have been the on–off period of aeration and the dissolved‐oxygen set point. The objective of the work has been to determine the optimal configuration of the aeration control to achieve a simultaneous removal of carbon (expressed as chemical oxygen demand [COD]) and nitrogen.  The results were obtained in a full‐scale bioreactor located at the wastewater treatment plant of Sant Celoni (Barcelona, Spain), where a nitrogen removal based on a nitrification–denitrification process is being tested. It has been shown that the crucial parameter to ensure a complete removal of COD and nitrogen is to give the system a long time of on–off aeration to complete both the nitrification and the denitrification processes, whereas the dissolved‐oxygen set point has a minor influence on the overall performance.  The results presented can be applied to a great number of similar systems, in which a nitrogen removal, based on a nitrification–denitrification scheme, is currently being tested or implemented.
Nitrogen Transformations Modeling in Subsurface‐Flow Constructed Wetlands
Authors: Liu Wenxin , Dahab Mohamed F. , Surampalli Rao Y.
Published: October 2005

Subsurface‐flow constructed wetlands (CWs) wastewater treatment typically results in satisfactory organics removal. However, the removal of nutrients, particularly nitrogen, is often unreliable, and typically less than desired, and nitrogen transformations in wetlands systems are not well‐understood. The principal objective of this study was to establish a basis for quantification of nitrogen transformations through subsurface flow CW systems. Actual performance data from a full‐scale facility located near Lincoln, Nebraska, were used to calibrate a proposed nitrogen transformations model, which, in turn, was used to replicate and predict the wetlands performance. To realize this objective, a compartmental analysis technique, which uses a set of differential equations and nonlinear optimization numerical methods, was used for solving nitrogen transformation rates and for predicting wetland performance. The model satisfactorily reproduced the mean effluent concentrations for organic nitrogen, ammonium‐nitrogen, and nitrate‐nitrogen, but with lesser accuracy with respect to peak high and low effluent concentrations. Nitrogen mass balance in the wetland was used to identify likely nitrogen transformation pathways. Generally, it was found that approximately one‐third of the influent nitrogen mass was removed through nitrification and denitrification, one‐third was removed through vegetative assimilation, and the remainder was discharged in the wetland effluent.