bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant Genetic Resources Conservation and Utilization: The Accomplishments and Future of a Societal Insurance Policy
Authors: Gepts Paul
Published: September 2006

Concerns about the genetic erosion of crop genetic resources (CGR) were first articulated by scientists in the mid‐20th century and have since become an important part of national policies and international treaties. The C‐8 (Plant Genetic Resources) section of the Crop Science Society of America (CSSA) was created in 1990 in response to these concerns. Over the last 50 yr, both ex situ and in situ conservation have been set up to maintain threatened CGR. During this period, a set of tools (core collections, molecular markers, and geographic information systems) has been adopted to facilitate conservation and utilization by breeders. Current and future trends include characterization of the genotypic basis of phenotypic variation and the evolutionary, ecological, and human factors that have shaped CGR. The intellectual property regime to which CGR are subjected since 1980 has limited the exchange of germplasm. It remains to be seen if these regimes will evolve so as to achieve basic goals of conservation of genetic diversity and traditional knowledge associated with diversity, while at the same time reward breeders and farmers. Funding of biodiversity conservation remains a critical point. Finally, broadening the conservation circle to establish closer collaborations with grassroots conservation movements and community seed banks is necessary to better conserve the broad range of CGR and as an essential starting point for participatory breeding efforts.
Fifty Years of Grassland Science Leading to Change
Authors: Nelson C. Jerry , Burns J. C.
Published: September 2006

Division C‐6 was established in 2000, but members associated with forages and grazinglands have been active in the Crop Science Society of America (CSSA) since its inception; 21 have served as President and many authored textbooks and comprehensive reference works. Complex forage and pasture mixtures were common in 1955, but shifted to monocultures in the 1960s and 1970s. Mixtures returned in the 1980s as N prices increased, broader values of legumes became known, nutritive value was better understood, and environmental issues increased. Alfalfa (Medicago sativa L.) for dairy production had strong leadership from the private sector in seed production and breeding. Tall fescue (Festuca arundinacea Schreb.) was well‐adapted, conserved soil, and extended grazing in the transition zone to increase beef cow–calf production. Bermudagrass [Cynodon dactylon (L.) Pers.] benefited from vegetative propagation, conserved soil, and was improved for adaptation, yield, and nutritive value. Yield advancements, except for a few species, have been discouraging. Management benefited from advances in disease resistance, methods for assessing nutritive value, and understanding the role of endophytic fungi. Modest increases in nutritive value, coupled with improved pasture management, have increased animal performance. Emerging interests include biomass, carbon sequestration, and roles of biodiversity. Molecular techniques offer potential to better understand the plants and make genetic progress.
An Evergreen Revolution
Authors: Swaminathan Monkombu Sambasivan
Published: September 2006

The Green Revolution was the product of alteration in plant architecture and physiological properties through breeding in wheat (Triticum aestivum L.), rice (Oryza sativa L.), corn (Zea mays L.), sorghum (Sorghum bicolor L.), and other crops. The semidwarf plant stature contributed to providing adequate nutrition to the plant for high productivity, without inducing lodging. It also increased the harvest index. Similarly, photoinsensitivity helped to match the crop cultivar to seasons with appropriate moisture availability. The Green Revolution led to increased production through higher productivity and, thereby, conserved arable land and forests. Green Revolution technology, however, was criticized by environmentalists, economists, and social scientists for its deficiencies. Economists stressed that, because market‐purchased inputs are needed for output, only resource‐rich farmers are able to take advantage of high‐yielding cultivars. Environmentalists emphasized that the excessive use of fertilizers and pesticides, as well as the monoculture of a few crop cultivars, will create serious environmental problems, including the breakdown of resistance and the degradation of soil fertility. Social scientists stressed that often women were excluded from technology‐based agriculture, leading to their marginalization. The Green Revolution, however, helped many developing countries, including India and China, to achieve a balance between population growth and food production. It contributed to an alignment of population growth to the human capacity to produce the needed food and other agricultural commodities.
Effects of different biosolids treatment systems on pathogen and pathogen indicator reduction
Authors: Ponugoti Prabhakar R. , Dahab Mohamed F. , Surampalli Rao
Published: September 2006

In this study, the effectiveness of different treatment systems in reducing pathogenic density levels was evaluated according to the criteria established by the U.S. Environmental Protection Agency municipal sludge rule (40 CFR Part 503 Rule). In a year‐long effort, wastewater and biosolids samples were analyzed for both indicator and pathogenic organisms from different existing treatment systems. The results indicate that anaerobic digestion was superior to aerobic digestion in reducing pathogen density levels under the given field conditions. Composting was far more superior to both anaerobic and aerobic digestion. This study demonstrates that the Class B requirements under the 503 Rule are reasonable and can be achievable by most existing treatment systems, whereas the Class A requirements under the same rule may not be easily achieved by many existing treatment works. The effects of volatile solids loading rates on anaerobic and aerobic digester performance were investigated. Under anaerobic digestion conditions, the log reductions in fecal coliform and fecal streptococci appeared to be dependent on volatile suspended solids (VSS) loading rates. However, this trend was not evident in aerobic digestion systems sampled. Salmonella density reductions did not appear to be dependent on VSS loading rates in either case.
Short‐term toxicity test based on algal uptake by Ceriodaphnia dubia
Authors: Lee Sang‐III , Na Eun‐Jung , Cho Young‐Ok , Koopman Ben , Bitton Gabriel
Published: September 2006

A Ceriodaphnia algal uptake suppression test (CAUST) was developed for short‐term toxicity screening. The test is based on the feeding behavior of C. dubia and requires as little as 1 hour contact time between C. dubia neonates and toxicant. Before the test, neonate digestive tracts were cleared by feeding yeast to the daphnids. Neonates were then exposed to toxicant, followed by addition of Scenedesmus subspicatus to the bioassay vessels. Daphnids were examined under bright‐field microscopy for presence of algae (indicated by a green‐colored digestive tract) or absence of algae. Uptake indicated no toxic effect, whereas absence of uptake indicated toxic inhibition. Median effective concentrations (EC50 values) were computed based on results over a range of dosed toxicant concentrations. Results for cadmium, zinc, copper, pentachlorophenol, phenol, cyanide, and selected pesticides showed that CAUST was similar in sensitivity to the standard 48‐hour C. dubia acute bioassay and was as sensitive as or more sensitive than the 1‐hour I.Q. test and 30‐minute Microtox.
Evaluating the conversion of an automotive paint spray‐booth scrubber to an activated‐sludge system for removing paint volatile organic compounds from air
Authors: Kim Byung R. , Podsiadlik Diane H. , Yeh Daniel H. , Salmeen Irving T. , Briggs Linda M.
Published: September 2006

Volatile organic compound emissions from painting operations are of primary concern in the automotive industry and require costly control measures using vapor‐phase activated‐carbon adsorption. At Ford Research Laboratory, Dearborn, Michigan, a process modification has been proposed as a supplemental or an alternative control measure to convert an existing paint‐sludge pit, part of a spray‐booth scrubber system, to an activated‐sludge reactor. Under this scheme, water‐soluble paint solvents, captured by the scrubber water from the booth air in the spray booth, are to be biologically degraded in the sludge pit. For this paper, the technical feasibility of the conversion was evaluated by conducting a laboratory experiment using a bench‐scale activated‐sludge reactor fed with nine selected paint solvents; analyzing the experimental data with Monod kinetics for substrate utilization and a first‐order kinetics for endogenous respiration; and estimating the performance of the paint‐sludge pit as a bioreactor at a typical assembly plant. Results showed that a paint‐sludge pit is sufficiently large to biologically destroy all captured paint solvents at a typical paint‐spraying rate if the pit is converted to a bioreactor; most of the oxygen‐supply requirement for degrading paint solvents, which is a significant operating cost item for activated sludge, could be provided by the existing spray‐booth air circulation at no extra cost; the rate of biomass production was estimated to be comparable to the rate of accumulation of overspray paint polymers; and the data agreed well with the Monod and first‐order respiration kinetics.
Principles in the design of single‐sludge activated‐sludge systems for biological removal of carbon, nitrogen, and phosphorus
Authors: Wentzel Mark C. , Ekama George A.
Published: September 2006

The function of the single‐sludge activated‐sludge system has expanded from chemical oxygen demand (COD) removal to include, progressively, nitrification, denitrification, and phosphorus removal, all biological. With such complexity, design procedures based on fundamental behavioral patterns are required. The fundamental principles of a steady‐state model for biological excess phosphorus removal (BEPR) that is based on the current understanding of the mechanisms of BEPR are described. The model can be used for design and to predict the expected system response under constant flow and load conditions. With the aid of the model, the influence of various parameters on the magnitude of phosphorus removal and the interactions between BEPR and nitrification and denitrification are examined. Principle variables that influence phosphorus removal are an influent wastewater characteristic—readily biodegradable chemical oxygen demand concentration— and process design parameters—anaerobic mass fraction and its subdivision and sludge age. Also, the model indicates that, in agreement with observations, preventing recycling of nitrate to the anaerobic reactor is one of the main considerations in design.
A simple technique for estimating the contribution of abiotic mechanisms to the removal of synthetic organic chemicals by completely mixed activated sludge
Authors: Grady C.P.L. , Magbanua B.S. , Brau S. , Sanders R.W.
Published: September 2006

Estimation of the contribution of abiotic removal mechanisms, such as volatilization and sorption, to the overall removal of a synthetic organic chemical (SOC) by the activated‐sludge process is often necessary. Recognition that the only effect of the abiotic mechanisms is to reduce the concentration of biomass involved in the biodegradation of the SOC provides the means for estimating that contribution. Knowledge of the fraction of the influent SOC concentration remaining in the effluent, the hydraulic and solids retention times, the mixed liquor suspended solids concentration, the volatilization rate coefficient, and the sorption coefficient allows rapid computation of the fractional removal resulting from the abiotic mechanisms.
Heterogeneous photocatalytic oxidation of nitrotoluenes
Authors: Kumar Shiva , Davis Allen P.
Published: September 2006

The photocatalytic oxidation rates of nitrotoluene (2‐NT and 3‐NT) and dinitrotoluene (2,4‐DNT and 2,6‐DNT) in aqueous suspensions of Degussa P‐25 were found to be pH independent because these compounds do not exhibit any pH‐dependent speciation. The reaction rates of mononitrotoluenes were found to be 60 to 80% greater than those of dinitrotoluenes. A Langmuir–Hinshelwood (L–H) rate form is used to describe the kinetics of the photocatalytic oxidation of these compounds. The L–H constant k1 has been found to be essentially independent of the compound being degraded. At low concentrations, the reaction rates of nitrotoluenes decrease with increasing nitration. This has been explained through the electron‐withdrawing characteristics of the nitro group, employing the Hammett relationship, with the reaction rates following the sequence Toluene > 3‐NT > 2‐NT > 2,4‐DNT > 2,6‐DNT > TNT (trinitrotoluene, predicted) The photocatalytic oxidation of 2,6‐DNT produces ammonium and nitrate ions. Attempts at augmenting the reaction rate by addition of hydrogen peroxide or Cu2+ ions did not significantly increase the reaction rate.
A case study of longitudinal dispersion in small lowland rivers
Authors: Sukhodolov Alexander N. , Nikora Vladimir I. , Rowiński Paweł M. , Czemuszenko Włodzimerz
Published: September 2006

Contaminant transport in natural streams is considered on the basis of tracer studies in Moldovian small lowland rivers. Theories describing the spread of conservative and passive pollutants in the context of a longitudinal dispersion model, as well as attempts to estimate the discrepancy between this model and natural processes, are discussed. It is shown that the model agrees with experimental data, with an accuracy ranging from 15 to 20%, at least in the upper [C(t) > 0.5Cmax] concentration distributions. The process behaves in a quasi‐Fickian manner only at distances greater than 80 to 100 times the river width. Primarily, the nonuniformity of the average velocities over cross sections affects the process. An estimate of the Lagrangian spatial scales was proposed, and it was shown that those scales are as large as two to four times the length of alternate bars.
Subsurface flow constructed wetlands treating municipal wastewater for nitrogen transformation and removal
Authors: Kemp Michael C. , George Dennis B.
Published: September 2006

Research was conducted on pilot‐scale, subsurface flow constructed wetland systems treating municipal wastewater. Increasing the hydraulic retention time (HRT) from 1.7 days to 4.3 days reduced the mean effluent NH4 concentration by 2.7 mg N/L. Hydroperiod manipulation caused a 2.9‐mg N/L decrease in effluent NH4. The influent NH4 concentration for the 9‐month study period averaged 21 mg N/L. The lowest average effluent NH4 concentration observed in single‐stage treatment cells was 13 mg N/L. The mean effluent NH4 concentration from the second‐stage cells of two wetland cells in series was 10 mg N/L. During the period from May through September, the second‐stage cells produced an effluent NH4 concentration of 6 mg N/L. A variable‐order kinetic model for sizing the second‐stage cells of a series system yielded a coefficient of determination, r2 of 0.94 for the summer NH4 removal data. The predicted HRT to reduce NH4 from 20 mg N/L to 5 mg N/L was 3.9 days, if the cells were subjected to cyclic draw and fill.
Quantitative near‐surface remote sensing of wastewater quality in oxidation ponds and reservoirs: a case study of the Naan system
Authors: Gitelson Anatoly , Stark Robert , Dor Inka
Published: September 2006

This study develops a remote sensing technique for real‐time monitoring of wastewater effluents stored before irrigation. Reflectance and attenuation coefficients for downwelling irradiance spectra (400 to 950 nm spectral resolution of 2 nm) were acquired simultaneously with turbidity, chlorophyll, organic matter, and total suspended matter concentrations in the Naan wastewater system, Israel. High‐spectral‐resolution spectrometric data were used to select the most suitable spectral bands for remote sensing of “optically active” constituent concentrations. Algorithms for remote estimation of wastewater quality expressed as chlorophyll‐a, bacteriochlorophyll‐a, and total suspended matter concentrations were developed. Reflectance height at 720 nm and an area above the base line from 670 to 950 nm was used in algorithms for chlorophyll‐a assessment (r2 > 0.83). For bacteriochlorophyll‐a assessment, an area under the base line through 780 to 900 nm was used, allowing its quantitative estimation (r2 > 0.94). Reflectance of approximately 570 and from 400 to 950 nm correlated closely with total suspended matter concentration (r2 > 0.82) and was used to retrieve it from reflectance spectra. This is the first reported study on the quantitative remote assessment of wastewater quality. The results suggest that four spectral bands be used for real‐time monitoring of wastewater ponds quality.
Full‐scale evaluation of factors affecting the performance of anoxic selectors
Authors: Marten William L. , Daigger Glen T.
Published: September 2006

Five full‐scale nitrifying activated‐sludge systems incorporating anoxic selectors were evaluated. Operating records were reviewed to determine selector performance (filament control) and to identify operating conditions that affected selector performance. Key operating parameters found to influence anoxic selector performance were selector loading, expressed in terms of the selector food‐to‐microorganism (F:M) ratio, wastewater temperature, and activated‐sludge system aerobic solids retention time (SRT). A target selector F:M ratio of 0.7 to 1.2 kg CBOD5 (carbonaceous biochemical oxygen demand)/kg MLSS (mixed liquor suspended solids) · d (lower values at cooler temperatures, higher values at warmer temperatures) and an aerobic SRT of 8 to 12 days were found to produce excellent selector performance. Increasing selector F:M or system aerobic SRT to greater than these ranges was found to result in persistent filamentous bulking.
Biodegradation of two polyethoxylated nonionic surfactants in sequencing batch reactors
Authors: Figueroa Linda A. , Miller Johanna , Dawson Helen E.
Published: September 2006

Application of surfactants to increase the mobility of hydrophobic contaminants in soils will create a secondary aqueous waste stream containing mobilized contaminant and surfactant that may be biodegraded. Previous research on surfactant biodegradation focused on low surfactant concentrations, typically less than 0.01% (weight/weight). The goal of this project was to investigate the effect of surfactant concentration, greater than 0.01%, on the rate and extent of surfactant biodegradation. Two nonionic polyethoxylated surfactants, Neodol 91‐8 and Makon 12, were selected for study based on their ability to solubilize hydrophobic organic compounds. Investigations were conducted in bench‐scale sequencing batch reactors at initial surfactant concentrations of 0.01, 0.025, and 0.05%. The surfactants served as the sole carbon source. The average residual nondegradable fractions of surfactant were 0.35 and 0.15 for Makon 12 and Neodol 91‐8, respectively. Although the extent of degradation did not change with initial surfactant concentration, the residual concentration did increase with initial surfactant concentration. Organic carbon removal was best fit by a modified first‐order model. The first‐order rate constant seemed to decrease exponentially with increasing initial surfactant concentration.
Low sludge carbohydrate content: a prerequisite for enhanced biological phosphate removal
Authors: Liu Yan‐Hua
Published: September 2006

The relationship between sludge carbohydrate (CH) content and phosphate (P) removal performance has been studied in two sequencing batch reactors (SBRs) exhibiting enhanced biological phosphorus removal (EBPR). Glucose and acetate were used as the main organic substrates for the two SBRs, respectively. The phosphorus removal performance was excellent when the sludge CH content ranged from 8 to 10% (CH/mixed liquor suspended solids), but it declined concomitantly as the sludge CH content increased beyond this range. The sludge CH content was found to be a reliable parameter representing its capacity for phosphorus removal. The change of the sludge CH content was mainly influenced by the characteristics of the substrates, as well as by the operation modes. The study, as a whole, suggests that the control of sludge CH content to low levels is a prerequisite for achieving enhanced phosphorus removal in EBPR process.
A novel process for recovery of phenol from alkaline wastewater: laboratory study and predesign cost estimate
Authors: Dutta Narendra N. , Borthakur Somiran , Baruah Rasna
Published: September 2006

A novel process for recovery of phenol from alkaline wastewater has been demonstrated at laboratory scale. The process is based on the polymer‐supported phase‐transfer‐catalyzed reaction of alkaline phenols with benzoyl chloride dissolved in toluene. The reaction conducted in a triphase system at room temperature generates phenyl benzoate, which is subsequently recovered as the product. Phosphonium ion immobilized on chloromethyl polystyrene crosslinked with divinylbenzene was used as the catalyst. Laboratory experiments were conducted in a batch slurry reactor and a fixed‐bed reactor to assess the suitability of a particular reactor type to practical applications. An aqueous phase to organic phase volume ratio of 1:2 was found to be suitable. The slurry reactor was found to be more attractive for the reaction. Based on the result of experiments in batch slurry reactors and other processing steps, a conceptual flow scheme was proposed for the process, and a predesign cost estimate was made. As such, the treatment cost of the proposed process is higher than that of the usual solvent extraction process, but the capital cost is comparable. However, the cost of the recovered phenyl benzoate will more than offset the higher treatment cost. This is reflected in a payback period of 1.5 years for the proposed process as compared to 2.5 years for the typical solvent extraction process. For industrial applications, a pilot‐plant study needs to be performed for a detailed cost analysis.
Secondary clarification of activated sludge: development of operating diagrams
Authors: Hermanowicz Slawomir W.
Published: September 2006

Operating diagrams for secondary clarification of activated sludge were developed based on the solids flux theory. The diagrams connect the process operational parameters—mixed liquor suspended solids, return activated sludge solids, and recycle ratio—in a unified graphical form. The diagrams can be used to design and analyze the performance of secondary clarification and to evaluate operating strategies in response to changes in flow rate or solids settleability.
A model for predicting contaminant removal by adsorption within the International Space Station water processor: 1. Multicomponent equilibrium modeling
Authors: Bulloch John L. , Hand David W. , Crittenden John C.
Published: September 2006

A thermodynamic model is developed to predict adsorption equilibrium in the International Space Station water processor's multifiltration beds. The model predicts multicomponent adsorption equilibrium behavior using single‐component isotherm parameters and fictitious components representing the background matrix. The fictitious components are determined by fitting total organic carbon and tracer isotherms with the ideal adsorbed solution theory. Multicomponent isotherms using a wastewater with high surfactant and organic compound concentrations are used to validate the equilibrium description on a coconut‐shell–based granular activated carbon (GAC), coal‐based GAC, and a polymeric adsorbent.
Effect of simultaneous biodegradation of multiple substrates on the extant biodegradation kinetics of individual substrates
Authors: Ellis Timothy G. , Smets Barth F. , Grady C.P. Leslie
Published: September 2006

A respirometric technique was developed to quantify the extant kinetics for biodegradation of an organic compound by biomass that is simultaneously degrading a complex mixture of substrates. The technique uses a fed‐batch feed to supply the mixture of substrates at a rate consistent with the organic loading on the completely mixed activated sludge (CMAS) bioreactor from which the biomass was obtained. The results were compared to results from a batch test wherein the target compound served as the sole carbon and energy source. Results from the fed‐batch technique showed that simultaneous biodegradation of multiple substrates caused an increased ability for the removal of the target compound, phenol, although the increase was relatively small. A 7 to 12% increase in the maximum specific growth rate was observed for biomass receiving a fed‐batch feed at a rate of one to three times the specific mass flow rate to the CMAS system. An increase in the fed‐batch feed rate to six times the CMAS rate caused a decrease from the maximum enhancement, which was observed at the threefold rate, indicating that there was an upper limit on the stimulatory effect. Less extensive studies with acrylamide, 4‐chlorophenol, ethylene glycol, and m‐toluate gave similar results. Because the effects of simultaneous substrate biodegradation were small, single‐substrate extant kinetic tests should be adequate for describing the capabilities of a biomass for degrading a particular substrate in a multisubstrate environment.
Estimating the safety of wastewater reclamation and reuse using enteric virus monitoring data
Authors: Tanaka Hiroaki , Asano Takashi , Schroeder Edward D. , Tchobanoglous George
Published: September 2006

The reliability of wastewater reclamation and reuse to meet a given annual risk of infection, considering the variability of enteric virus concentrations, has been investigated. Two concepts related to the reliability and safety of wastewater reclamation and reuse are presented. The first is reliability, defined as the probability that the risk of infection from enteric viruses in reclaimed wastewater does not exceed an acceptable risk. The second is based on the expectation of the acceptable annual risk in which the exposure to enteric viruses may be estimated stochastically by numerical simulation. To assess the potential risks associated with the use of reclaimed wastewater in various reuse applications, four exposure scenarios were tested: golf course irrigation, food crop irrigation, recreational impoundments, and groundwater recharge. Past monitoring data on enteric virus concentrations in unchlorinated secondary effluents in California were used. Because enteric virus concentrations in unchlorinated secondary effluents were found to vary over a wide range, characterizing their variability was found to be extremely important. The reliability criterion of meeting the less than 10−4 annual risk of infection (less than or equal to one infection per 10 000 population per year) at least 95% of the time was used to assess the safety of using reclaimed wastewater in the four different exposure scenarios. The methodologies used in this study should be refined, based on a larger enteric virus database developed using standardized field and laboratory protocols.
Anaerobic fluidized‐bed treatment of propellant wastewater
Authors: Maloney Stephen W. , Engbert Edward G. , Suidan Makram T. , Hickey Robert F.
Published: September 2006

Treatment of propellant wastewater by anaerobic fluidized‐bed bioreactors (FBRs) containing granular activated carbon has been shown to be effective in laboratory and field feasibility studies. These studies were conducted in 100 mm (4 in.) diameter columns (8 L volume) treating low volumes of water taken directly from a propellant‐production operation. The contaminant of interest, dinitrotoluene, was converted anaerobically to diaminotoluene (DAT), with subsequent aerobic mineralization of the DAT in an activated‐sludge process. A demonstration of this technology has been conducted at Radford, Virginia, Army Ammunition Plant, using a commercially available 500 mm (20 in.) diameter column (710 L volume) FBR modified for anaerobic operation. The FBR was followed in series by a rotating biological contactor to simulate anaerobic pretreatment at a point source, followed by aerobic treatment at the existing facilities. Significant differences in the composition of the wastewater stream were encountered between the feasibility study and demonstration. The concentrations of easily degraded solvents (ethanol and ether) were much lower during the demonstration than during the feasibility studies. The events encountered in scaling up the process from the laboratory to pilot scale are reported, and the results of the pilot‐scale demonstration are compared with the laboratory‐scale data.
Biodegradation of dichloromethane in a granular activated carbon fluidized‐bed reactor
Authors: Flanagan William P.
Published: September 2006

A biological fluidized‐bed reactor (FBR) containing biomass attached to granular activated carbon (GAC) was investigated for the treatment of aqueous‐phase dichloromethane (DCM). The system was directly inoculated with fresh biomass solids collected from a General Electric Plastics wastewater treatment facility, located in Mount Vernon, Indiana. The biomass consumed DCM as its sole carbon and energy source following an acclimation period of approximately 8 days. Dichloromethane biodegradation rates in excess of 40 kg/m3 · d were achieved during continuous operation, with no detectable DCM (<1 mg/L) in the process effluent. Steady‐state data were collected to enable process scale‐up. This study confirmed that the biological GAC FBR is an environmentally acceptable waste treatment configuration for the destruction of aqueous‐phase DCM.
Development of a revised metabolic model for the growth of phosphorus‐accumulating organisms
Authors: Filipe Carlos D.M. , Daigger Glen T.
Published: September 2006

The performance of a metabolic model for biological phosphorus removal (BPR) and that of a model based on continuous‐flow data were compared. Analysis showed that the metabolic model does not correctly simulate the behavior of BPR systems. The reason was found to be the kinetic expressions forming the basis of the model. A new set of kinetic expressions was selected, and a revised metabolic model was tested. It was shown that the revised metabolic model is capable of describing reported data using a single set of stoichiometric and kinetic parameters (except for the maintenance coefficient). This finding suggests that the model may be broadly applicable to a wide range of applications. A model for the dependence of the ratio of phosphorus released per acetate taken up (P/Hac ratio) on the pH of the medium was also developed, and this relationship was found to be linear.
A laboratory study of the bioremediation of 2,4,6‐trinitrotoluene‐contaminated soil using aerobic/anoxic soil slurry reactor
Authors: Boopathy Ramaraj , Manning John , Kulpa Charles F.
Published: September 2006

The successful operation of an aerobic/anoxic laboratory‐scale soil slurry reactor showed that soil contaminated with 2,4,6‐trinitrotoluene (TNT) and hexahydro‐l,3,5‐trinitro‐l,3,5‐triazine (RDX) could be treated in batches or semicontinuously. Batch treatment resulted in the transformation of TNT. Semicontinuous treatment resulted in complete degradation of TNT. In addition to removing TNT, the slurry reactor also removed contaminants such as trinitrobenzene, 2,4‐dinitrotoluene, RDX, and octahydro‐l,3,5,7‐tetranitro‐l,3,5,7‐tetraazocine (HMX). Radiolabeled TNT incubated with reactor biomass showed that 23% of [14C]TNT was mineralized, 27% was converted to biomass, and 8% was adsorbed onto the soil. The rest of the [14C]TNT was accounted for as metabolites, including a ring cleavage product identified as 2,3‐butanediol. Increasing the frequency of soil addition from once to two or three times weekly did not affect the TNT removal rates. The soil slurry reactor also maintained the bacterial population fairly well, needing only 0.3% molasses as a cosubstrate.
Sludge volume index settleability measures: effect of solids characteristics and test parameters
Authors: Bye Christopher M. , Dold Peter L.
Published: September 2006

Sludge volume index (SVI) type activated‐sludge settleability measures are used in the design and control of secondary settling tanks. Considerable confusion exists as to the best parameter and experimental technique to use. The common settleability measures (SVI, diluted sludge volume index, stirred specific volume index [SSVI], and SSVI at 3.5 g/L) are outlined. This discussion is used as the basis for commenting on the validity of these measures and their relation to zone settling velocity measurements. A simple mechanistic model is used to evaluate the effects of solids characteristics and test parameters on SVI‐type indices. Solids settleability and compactability, settling column height, and solids concentration in the test have an interactive effect on the measured SVI. The applied model explains many of the artifacts associated with SVI and questions the validity of correlations for zone settling parameters based on SVI‐type measurements.
Substrate inhibition of degradation of 2,4‐dinitrophenol in activated sludge
Authors: Jo Kwan‐Hyung , Silverstein JoAnn
Published: September 2006

Substrate inhibition of 2,4‐dinitrophenol (2,4‐DNP) degradation was investigated in activated sludge previously adapted to mineralize low concentrations of DNP. Typically, the time required for 95% degradation of 10 mg/L DNP under aerobic conditions and with mixed liquor suspended solids (MLSS) of 600 to 1 000 mg/L was less than 4 hours without any lag. However, when the initial DNP concentration increased to 75 mg/L, lags and even complete inhibition of DNP degradation were observed. The length of the lag was found to increase proportionally with decreasing MLSS. When dilute activated sludge was incubated for extended periods (192 hours), degradation of 75 mg/L DNP did eventually occur after lag periods of 37 to 144 hours, depending on MLSS concentration. Assays for most probable number of DNP‐degrading bacteria were made to ascertain the effect of high DNP concentrations on bacterial populations in the activated sludge.
Acute and chronic toxicity of industrial and municipal effluents in Maryland, U.S.
Authors: Fisher Daniel J. , Knott Melvin H. , Turley Bonnie S. , Yonkos Lance T. , Ziegler Gregory P.
Published: September 2006

Since 1987, an effluent biomonitoring program of major and selected minor industrial and municipal point source dischargers has been conducted for Maryland's Department of the Environment. Acute and chronic toxicity test procedures were developed and implemented for testing freshwater (Pimephales promelas, Daphnia magna, and Ceriodaphnia dubia) and estuarine (Cyprinodon variegatus and Mysidopsis bahia) invertebrates and fish. Results from the laboratory bioassays were used by Maryland to identify toxic discharges to state waters. Beginning in 1987, totals of 488 and 89 effluent samples were tested for acute and chronic toxicity, respectively. Both the frequency of acute and chronic toxicity and the severity of the toxicity of the remaining toxic effluents have decreased dramatically since the inception of the program. Examples are presented concerning the use of these data by Maryland to regulate toxic discharges. These results indicate the important role whole‐effluent toxicity testing plays in controlling the point source discharge of toxic substances to surface waters.
A biological index to predict pulp mill pollution levels
Authors: Bard Shannon Mala
Published: September 2006

The species diversity of mid to low rocky intertidal beaches along the protected coast of British Columbia, Canada, increases significantly as exposure to pulp mill effluent decreases. Species were categorized according to hardiness and ranked as either pollution tolerant, sensitive, or intolerant. Indicator species whose presence or abundance is highly correlated to exposure to mill effluent were discovered. A biological index (Bioindex) was developed to predict a rocky shore's exposure to mill effluent by analyzing the hardiness of the resident biota. The Bioindex is useful to evaluate the environmental stress from pulp mills, to pinpoint depleted beaches for cleanup, and to evaluate pristine areas to be protected. The Howe Sound mills were found to have the most detrimental and widespread effect on rocky shore beaches of all regions surveyed, followed, in order of decreasing severity, by the Crofton mill, the Prince Rupert mill, and the Powell River mill.
Molecular Modeling
Authors: Boyd Donald B.
Published: September 2006

The article contains sections titled:1.Definitions2.Purpose of Modeling3.Brief History4.Methodologies of Molecular Modeling4.1.Computer Graphics4.2.Databases4.3.Conformational Modeling4.4.Quantum Mechanical Modeling4.5.Force Field Modeling4.6.Statistical Modeling4.7.Homology Modeling4.8.Drug Design Modeling5.Economic Aspects

Molecular modeling is used to understand the characteristics of molecules and to design new molecules in industry and elsewhere. The computer‐based techniques of molecular modeling include molecular mechanics, molecular graphics, and many other methodologies of computational chemistry. Most large research‐based companies involved in molecular science, particularly pharmaceutical companies, use molecular modeling daily.
Enzyme and Immunoassays
Authors: Miller James N. , Niessner Reinhard , Knopp Dietmar
Published: September 2006

The article contains sections titled:

1.Enzymatic Analysis Methods1.1.Introduction1.2.Enzymes: Basic Kinetics1.3.Enzyme Assays: Practical Aspects1.3.1.General Considerations1.3.2.Spectrometric Methods1.3.3.Other Methods1.3.4.Effects of pH, Buffer, Composition, and Temperature1.3.5.Sources and Activity of Enzymes1.4.Enzyme Assays: Determination of Substrates1.4.1.General Considerations1.4.2.Determination of Glucose1.4.3.Determination of Ethanol1.5.Enzyme Assays: Determination of Inhibitors1.5.1.Inhibitors of Cholinesterase Enzymes1.5.2.Other Inhibition Methods1.6.Enzyme Assays: Determination of Activators1.6.1.Determination of Metal Ions by Metalloenzymes1.6.2.Other Activator Analyses1.7.Immobilized Enzymes1.7.1.Introduction1.7.2.Properties of Immobilized Enzymes1.7.3.Application of Immobilized Enzymes2.Immunoassays in Analytical Chemistry2.1.Introduction2.2.Polyclonal, Monoclonal, and Recombinant Antibodies2.3.Sample Conditioning2.4.Immunoassays2.4.1.Radioimmunoassay2.4.1.1.Isotopic Dilution Radioimmunoassay2.4.1.2.Immunoradiometric Assay (IRMA)2.4.2.Nonisotopic Homogeneous Immunoassay2.4.2.1.Latex Particle Agglutination Immunoassay2.4.2.2.Enzyme‐Multiplied Immunoassay Technique (EMIT)2.4.2.3.Apoenzyme Reconstitution Immunoassay System (ARIS)2.4.2.4.Fluorophore‐Labeled Homogeneous Immunoassay2.4.2.5.Homogeneous Fluorescence Polarization Immunoassay (FPIA)2.4.2.6.Homogeneous Liposome Immunoassay2.4.3.Nonisotopic Heterogeneous Immunoassay2.4.3.1.Enzyme‐Linked Immunosorbent Assay (ELISA)2.4.3.2.Sandwich Immunoassay2.4.3.3.Immunoassays using Immobilized Affinity Ligands2.4.3.4.Immunoassays with Biotin and Avidin2.4.3.5.Magnetic Particle Immunoassay2.5.Immunoaffinity Techniques2.6.Immunoassays on Test Strips and other Planar Structures2.7.Characterization and Interference2.8.Future Immunological Applications and Techniques
Metallocenes
Authors: Kaminsky Walter
Published: September 2006

The article contains sections titled:

1.

Introduction

2.

Polyethylene and Polypropylene

3.

Cycloolefin Copolymers

4.

Syndiotactic Polystyrene

5.

Supporting of Metallocene Catalysts

By application of metallocenes a new catalyst family has been introduced into polyolefin production, the most quickly growing market in the polymer industries. The easy modification of the metallocene catalyst structure brought about improvements in catalyst activities, comonomer incorporation, and polymer properties. It became possible to tailor in a wide range the microstructure of polyolefins such as chain length, molecular mass distribution, polypropylene tacticity, and comonomer distribution.

Ethylene/oct‐1‐ene and cycloolefin copolymers, syndiotactic or isoblock polypropylenes and syndiotactic polystyrene are some types of new industrially produced polymers. The polyolefins synthesized by metallocene catalysts show a narrow molecular mass distribution of 2 and in some cases long chain branches.
Centrifuges, Sedimenting
Authors: Axelsson Hans , Madsen Bent
Published: September 2006

The article contains sections titled:

1.Introduction2.Fundamentals2.1.Centrifugal Sedimentation2.2.Centrifugal Sedimentation with Continuous Flow3.Centrifugal Separators with Continuous Feed3.1.General3.2.Disk‐Bowl Machines3.3.Chamber and Multichamber Bowls3.4.Tubular Bowl Centrifuges3.5.Decanter Centrifuges3.6.Other Bowl Geometries4.Batch Centrifuges4.1.General4.2.Bottle Centrifuges4.3.Batch Zonal Centrifuges5.Fluid Dynamics in Centrifuges5.1.Chamber and Tubular Bowl Centrifuges5.2.Disk‐Bowl Centrifuges5.3.Decanter Centrifuges6.Centrifuge Technology6.1.Rotor Dynamics6.2.Materials Selection7.Centrifuge Selection7.1.Introduction7.2.Main Process Parameters7.3.Test Tube Centrifugation (Spin Test)7.4.Important Properties of the Process Streams7.5.Improvement of Separability7.6.Pilot Machine Testing7.7.Scale‐Up8.Applications
Custom Synthesis and Custom Chemicals
Authors: Polastro Enrico T.
Published: September 2006

The article contains sections titled:

1.

Introduction

2.

Genesis

3.

Supply Structure

4.

Customer Base

5.

Contractual Relations

6.

Key Success Factors

7.

Industry Size and Growth

8.

Concluding Remarks
Intermetallics
Authors: Sauthoff Gerhard
Published: September 2006

The article contains sections titled:1.Introduction1.1.Definition of Intermetallics1.2.Historical Remarks2.General Considerations2.1.Crystal Structure and Compound Stability2.2.Basic Properties2.3.Criteria for Compound Selection3.Magnetic Materials3.1.AlNiCo Alloys3.2.FeCo Alloys3.3.Sendust Alloy3.4.Laves Phases3.5.Rare‐Earth Compounds4.Superconducting Materials4.1.Laves Phases4.2.A15 Compounds4.2.1.V3Si4.2.2.V3Ga4.2.3.Nb3Sn4.2.4.Nb3Al4.2.5.Nb3Si5.Electronic Materials5.1.Silicides5.2.Other Compounds6.Electric Materials7.Thermoelectric and Thermomagnetic Materials7.1.Silicides7.2.Other Thermoelectric Compounds7.3.Thermomagnetic Compounds8.Optical Materials9.Hydrogen‐Storage Materials9.1.B2 Compounds9.2.Laves Phases9.3.Rare Earth Metal Compounds and Other Phases10.Electrode Materials10.1.Mg2Ni Alloys10.2.Laves Phase Alloys10.3.RNi5Alloys11.Coating Materials11.1.Aluminides11.2.Silicides12.Shape‐Memory Materials12.1.Cu‐Base Alloys12.1.1.Cu ‐ Zn ‐ Al Shape Memory Alloys12.1.2.Cu ‐ Al ‐ Ni Shape‐Memory Alloys12.2.NiAl Alloys12.3.NiTi Alloys13.Medical Biomaterials14.Dental Materials14.1.Amalgams14.2.Cu ‐ Au Alloys15.Wear‐Resistant Materials16.Structural High‐Temperature Materials16.1.Titanium Aluminide Alloys16.1.1.Ti3Al Alloys16.1.2.TiAl Alloys16.2.Iron Aluminide Alloys16.2.1.Fe3Al Alloys16.2.2.FeAl Alloys16.3.Nickel Aluminide Alloys16.3.1.Ni3Al alloys16.3.2.NiAl Alloys16.4.Silicide Alloys
Cover Picture: Solution‐Processed Organic Tandem Solar Cells (Adv. Funct. Mater. 14/2006)
Authors: Hadipour A. , de Boer B. , Wildeman J. , Kooistra F. B. , Hummelen J. C. , Turbiez M. G. R. , Wienk M. M. , Janssen R. A. J. , Blom P. W. M.
Published: September 2006

The fabrication of a solution‐processed polymer tandem cell by stacking two single cells in series is reported by de Boer and co‐workers on p. 1897. The bottom and top cell are complementary with respect to their absorption spectra and the layer thickness of the bottom cell was optimized in order to create an optical cavity that efficiently transmits the required wavelength for the top cell. The combination of this tandem architecture with more efficient small‐bandgap materials will enable the realization of highly efficient organic solar cells.

A solution‐processed polymer tandem cell fabricated by stacking two single cells in series is demonstrated. The two bulk‐heterojunction subcells have complementary absorption maxima at λmax ∼ 850 nm and λmax ∼ 550 nm, respectively. A composite middle electrode is applied that serves both as a charge‐recombination center and as a protecting layer for the first cell during spin‐coating of the second cell. The subcells are electronically coupled in series, which leads to a high open‐circuit voltage of 1.4 V, equal to the sum of each subcell. The layer thickness of the first (bottom) cell is tuned to maximize the optical absorption of the second (top) cell. The performance of the tandem cell is presently limited by the relatively low photocurrent generation in the small‐bandgap polymer of the top cell. The combination of our tandem architecture with more efficient small‐bandgap materials will enable the realization of highly efficient organic solar cells in the near future.
Cover Picture: A Single Polymer Nanowire Photodetector (Adv. Mater. 18/2006)
Authors: O'Brien G. A. , Quinn A. J. , Tanner D. A. , Redmond G.
Published: September 2006

Redmond and co‐workers report on p. 2379 the successful application of solution‐assisted template wetting to the high‐yield controlled synthesis of poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐co‐(bithiophene)] (F8T2) nanowires (main picture and lower inset). Photoconductivity measurements (schematic in center) yield single‐nanowire device responsivities of ca. 0.4 mA W–1 and external quantum efficiencies of ca. 0.1 % under monochromatic illumination, comparable with data reported for single inorganic nanowire devices.
The One‐Pot Wittig Reaction: A Facile Synthesis of α,β‐Unsaturated Esters and Nitriles by Using Nanocrystalline Magnesium Oxide
Authors: Choudary Boyapati M. , Mahendar Koosam , Kantam M. Lakshmi , Ranganath Kalluri V. S. , Athar Taimur
Published: September 2006

Nanocrystalline magnesium oxide was found to be an effective heterogeneous, solid base catalyst for the one‐pot Wittig reaction to afford α,β‐unsaturated esters and nitriles in excellent yields with high E‐stereoselectivity in the presence of triphenylphosphine under mild conditions.
Pyridin‐, Quinolin‐ and Acridinylidene Palladium Carbene Complexes as Highly Efficient C–C Coupling Catalysts
Authors: Schneider Sabine K. , Roembke Patric , Julius Gerrit R. , Raubenheimer Helgard G. , Herrmann Wolfgang A.
Published: September 2006

A series of four new complexes bearing N‐heterocyclic carbene ligands (NHCs) as well as four compounds bearing N‐heterocyclic carbene ligands with remote heteroatoms (rNHCs) of the general types [(NHC)(PPh3)2PdCl]+BF4− and [(rNHC)(PPh3)2PdCl]+BF4−, respectively, have been prepared in high yields. Crystal and molecular structures have been determined for four representative examples. These compounds proved to be efficient catalysts for aryl coupling reactions of the Heck and Suzuki types (reaching TONs of as high as 6,200,000). Both aryl bromides and aryl chlorides can be used as substrates. Like the well known mixed, standard (NHC)(phosphine) compounds, the new six‐numbered, one‐N‐heterocyclic carbene complexes (and in particular certain rNHC‐containing ones) also combine the advantageous stability of bis(carbene) and the high activity of bis(phosphine) complexes. Furthermore, their good catalytic performance and, especially, their easy synthesis based on cheap and commercially available starting materials, make them by far superior when compared to the mixed (NHC)(phosphine) catalysts known thus far.