bluuebunny/crossref_metadata_2025 huggingface dataset:
A philosophy for a performance specification for road foundations
Authors: Rogers C. D. F. , Fleming P. R. , Frost M. W.
Published: November 2009

The road foundation layers perform several functions both during construction and when the road is in service, for example load-spreading, temporary haul routes, and a base for the overlying construction layers. The critical loading condition is usually directing trafficking where the applied stresses are greatest. The capping and sub-base layers during construction require adequate stiffness and strength to resist these stresses. The current UK specification for road foundations is based on a recipe approach, and, unless permission is granted to use an analytical design, the pavement foundation designs are based entirely on the California Bearing Ratio (CBR) to characterise the subgrade, capping and sub-base materials. Here CBR is used as an index of both material strength and stiffness, although it measures neither directly. Such an approach is potentially inefficient and does not readily facilitate the use of new and marginal materials or alternative design procedures. Recent technical advances in laboratory and in situ testing of pavement foundation materials now allow the performance parameters of stiffness, strength and resistance to permanent deformation to be measured both for design and during construction. This in turn enables a performance-based specification for road foundation layers to be introduced to provide some assurance of the as-constructed quality, and by permitting the use of secondary or recycled aggregates, to contribute to the parallel goal of sustainable construction. This paper sets out an idealised philosophy for a performance-based specification for road foundations, examines the individual elements of the specification in relation to current knowledge and makes recommendations for a phased introduction alongside CBR-based methods.
Vision 2030: transport visions for strategic highways
Authors: Eastman R. , Miles J. C. , Wilkinson J.
Published: November 2009

This paper reports work done three years ago for the Highways Agency in England to stimulate long-term thinking about how to develop and operate the strategic highway network in the UK. The effects of road traffic are becoming a critical problem throughout the world, and without some radical solutions the situation is forecast to get worse. Problems such as traffic congestion, global warming and how to achieve sustainability are politically sensitive yet require positive action. Innovative thinking is needed now to develop solutions and actions that are good for the long term. The Highways Agency in its role as network operator is responsible for managing, maintaining and improving the strategic road network in England—over 8000 km of motorways and trunk roads. In a bid to look beyond the usual 5–10 year planning cycle, the Highways Agency commissioned the Vision 2030 Project. Visioning techniques and innovative thinking were used to develop several possible scenarios and propositions for the long-term future of inter-urban transport. These transport visions have influenced the Highways Agency in developing suitable action plans to achieve the desired levels of service for users of the strategic road network, against a changing and challenging background.
Injuries and fatalities in Turkish road traffic accidents
Authors: Gökdağ M. , Kaya M. D. , Atalay A. , Haşiloğlu A. S.
Published: November 2009

This study aims to describe quantitatively the injuries and fatalities from high rates of serious road traffic accidents (RTAs) in Turkey, to identify any trends during the period 1980–2000, to compare the results with those of developed countries and to evaluate the information available on possible causes with a view to identifying the most useful direction for future research. Data were obtained from the Turkish police, State Institute of Statistics, health sources and, for international comparison, from the published literature. Estimates of trends were made using linear regression. The results revealed that during the period 1980–2000, the rates of RTAs per 100 000 population and per 100 000 motor vehicles increased. Deaths in each RTA increased in the short period (1980–1987) and declined during the period 1987–2000. RTA injuries during the period 1980–2000 increased steadily. Between 1980 and 2000 the severity rate (the ratio of fatalities per 1000 RTAs) decreased threefold in Turkey. Turkey's rates were compared to a number of selected countries. Further investigation requiring close collaboration between police and health authorities is therefore essential.
Railway risks, safety values and safety costs
Authors: Evans A. W.
Published: November 2009

This paper has two principal sections. The first reviews railway risks since 1967, focusing on fatal collisions, derailments and overruns on running lines of the national railway system. Risks for most types of accident have declined substantially, but until the recent completion of the train protection and warning system, fatal accidents due to trains passing signals at danger at conflicting junctions persisted at about one accident per billion train-kilometres. The second main section discusses the valuation and costs of preventing rail fatalities, contrasting these with the valuation and costs of preventing road fatalities. The paper concludes by noting that society could prevent more fatalities at the same cost by devoting relatively more resources to road safety and less to rail safety, but is apparently content not to do so.
Increased damage to uphill flexible pavements from trucks
Authors: Razouki S. S. , Radeef H. Y.
Published: November 2009

The destructive effect of single-unit trucks on uphill slopes expressed in terms of flexible pavement truck equivalency factors was established. Charts for the truck equivalency factors for various truck weights were developed for various practical values of upgrades, H/B ratio (where H refers to the height of centre of gravity of the truck above the pavement and B refers to the length of wheel base of the truck), structural number (SN) and terminal level of serviceability (pt). The parameters introduced were derived from an axle load survey extending over about five months and covering 314 single-unit trucks. During the survey, the weight of each truck and the corresponding individual axles were determined together with the length of the wheel base. Based on the geometrical data collected during the survey, an estimate for the upper and lower limits for the H/B ratio was established. Due to the redistribution of axle loads on upgrades, use was made of equilibrium equations for determining the axle loads on each upgrade. The paper reveals that the truck equivalence factor is strongly affected by the H/B ratio and the magnitude of upgrade, particularly for truck weights exceeding about 200–250 kN.
Driving style extremes and potential vehicle emission effects
Authors: Felstead T. , McDonald M. , Fowkes M.
Published: November 2009

Chassis dynamometer driving cycles designed to quantify vehicle emissions often miss the extremes in driver behaviour. The vehicle emissions measured during these driving cycles are used for modelling and policy purposes. To better understand the impact of omitting such extremes, two drivers were asked to follow a set of behavioural rules to replicate ‘aggressive’ and ‘passive’ driving styles along a real-world route in Southampton, UK. The test route included a wide range of traffic conditions that could be expected on urban roads. The resulting driving profiles were compared to a number of legislative driving cycles – this indicated that aggressive driving was poorly addressed by these cycles. When replicated on a chassis dynamometer, the aggressive profile produced carbon monoxide, oxides of nitrogen and carbon dioxide emission rates of 2·68, 0·853 and 183·6 g/km, respectively, whereas the passive profile produced only 0·064, 0·011 and 124·4 g/km, respectively. Non-inclusion of aggressive driving styles in legislative driving cycles will mean that driving events that lead to disproportionately high emissions are not addressed by legislation designed to improve overall vehicle emissions control performance (e.g. Euro standards). In addition, a proportion of vehicle emissions will be missed from the modelling process which may have implications for local authorities declaring Air Quality Management Areas.
Control of structural risks arising from track replacement
Authors: Bailey R. P.
Published: November 2009

Metronet's extensive programme of ballasted track replacements on London Underground lines causes a large number of high-consequence, low-probability structural risks. (The name ‘Metronet’ has recently ceased being used.) The acceptable level of risk is discussed. Many of the risks involve small temporary adverse changes, and it is shown that these are not acceptable simply because they are small. Economical mitigations of risk, involving reasoning or modest modification of the conditions during the track replacement, are described for situations where calculation alone cannot demonstrate an acceptable level of risk.
User Perspective: Blind people and shared surface developments
Authors: Bates M. David
Published: November 2009

Few engineers and planners understand how a blind person navigates through the urban infrastructure they create. Shared surface areas have no safe footways for the blind and can be very disorientating, especially when the navigation markers used by the blind are moved or missing. This is written from the perspective of a blind engineer, and it enables the reader to imagine what being a pedestrian without sight is like.
Aggregate‐Scale Heterogeneity in Iron (Hydr)oxide Reductive Transformations
Authors: Tufano Katharine J. , Benner Shawn G. , Mayer Klaus U. , Marcus Matthew A. , Nico Peter S. , Fendorf Scott
Published: November 2009

There is growing awareness of the complexity of potential reaction pathways and the associated solid‐phase transformations during the reduction of Fe (hydr)oxides, especially ferrihydrite. An important observation in static and advective‐dominated systems is that microbially produced Fe(II) accelerates Ostwald ripening of ferrihydrite, thus promoting the formation of thermodynamically more stable ferric phases (lepidocrocite and goethite) and, at higher Fe(II) surface loadings, the precipitation of magnetite; high Fe(II) levels can also lead to green rust formation, and with high carbonate levels siderite may also be formed. This study expands this emerging conceptual model to a diffusion‐dominated system that mimics an idealized micropore of a ferrihydrite‐coated soil aggregate undergoing reduction. Using a novel diffusion cell, coupled with micro‐x‐ray fluorescence and absorption spectroscopies, we determined that diffusion‐controlled gradients in Fe2+(aq) result in a complex array of spatially distributed secondary mineral phases. At the diffusive pore entrance, where Fe2+ concentrations are highest, green rust and magnetite are the dominant secondary Fe (hydr)oxides (30 mol% Fe each). At intermediate distances from the inlet, green rust is not observed and the proportion of magnetite decreases from approximately 30 to <10%. Across this same transect, the proportion of goethite increases from undetectable up to >50%. At greater distances from the advective‐diffusive boundary, goethite is the dominant phase, comprising between 40 and 95% of the Fe. In the presence of magnetite, lepidocrocite forms as a transient‐intermediate phase during ferrihydrite‐to‐goethite conversion; in the absence of magnetite, conversion to goethite is more limited. These experimental observations, coupled with results of reactive transport modeling, confirm the conceptual model and illustrate the potential importance of diffusion‐generated concentration gradients in dissolved Fe2+ on the fate of ferrihydrite during reduction in structured soils.
In Situ Monitoring of Water Percolation and Solute Transport Using a Vadose Zone Monitoring System
Authors: Dahan Ofer , Talby Ruti , Yechieli Yoseph , Adar Eilon , Lazarovitch Naftali , Enzel Yehouda
Published: November 2009

Water percolation and tracer migration through the vadose zone underneath an ephemeral channel were studied using a vadose zone monitoring system (VMS) and application of a multitracer test. The VMS included flexible time‐domain reflectometry (FTDR) probes for continuous tracking of water content profiles, and vadose zone sampling ports (VSPs) for frequent sampling of the deep vadose pore water at multiple depths. The VMS was installed directly under an infiltration pond with several infiltration rings containing a traceable solution. Water content measurements by the FTDR probes allowed detailed visualization of the vadose wetting process; VSP samples allowed the establishment of tracer breakthrough curves at various depths. Flow velocities and fluxes were calculated from both the wetting process and the tracer breakthrough curves. The multitracer experiment revealed an unsteady flow pattern strongly affected by the layered structure of the sediments. The tracer breakthrough curves indicated domination of a mobile–immobile flow mechanism controlling contaminant migration across the vadose zone. The experimental setup demonstrated the ability of the VMS to provide real‐time monitoring of water flow and contaminant transport in the vadose zone.
Soil Profile Water Content Determination: Spatiotemporal Variability of Electromagnetic and Neutron Probe Sensors in Access Tubes
Authors: Evett Steven R. , Schwartz Robert C. , Tolk Judy A. , Howell Terry A.
Published: November 2009

Since the late 1980s, electromagnetic (EM) sensors for determination of soil water content from within nonmetallic access tubes have been marketed as replacements for the neutron moisture meter (NMM); however, the accuracy, variability and physical significance of EM sensor field measurements have been questioned. We studied the accuracy and variability of four EM sensors and the NMM, compared with gravimetric measurements, in transects of 10 to 20 access tubes during three field seasons, using soil‐specific calibrations. The three capacitance EM sensors produced water content readings for which SD values were up to an order of magnitude larger than those from the NMM. The EM sensor based on travel time (waveguide) principles produced SD values up to six times larger than those of the NMM or gravimetric sampling. The EM sensors would require from two to 72 times as many access tubes to obtain a mean profile water content to a given precision than would the NMM or gravimetric sampling, with more tubes required for drier conditions. The NMM exhibited spatial variation of similar magnitude and pattern as that of gravimetrically sampled profile water contents. The EM methods poorly reproduced the spatial and temporal behavior of NMM and gravimetric sampling and implied spatial variability of profile water content that was not evident in either the NMM or gravimetric data, even though EM sensing volumes were larger than the ∼75‐cm3 volume of the gravimetric samples. We infer that EM sensors were influenced not only by the mean water content in the sampling volume but by the smaller scale structure of soil electrical properties.
The Solute Diffusion Coefficient in Variably Compacted, Unsaturated Volcanic Ash Soils
Authors: Hamamoto Shoichiro , Perera Mandadige Samintha Anne , Resurreccion Augustus , Kawamoto Ken , Hasegawa Shuichi , Komatsu Toshiko , Moldrup Per
Published: November 2009

The solute diffusion coefficient in soil (Ds) and its dependency on the soil water content (θ), soil type, and compaction govern the transport and fate of dissolved chemicals in the soil vadose zone. Only a few studies have quantified solute diffusivity (Ds/D0, where Ds and D0 are the solute diffusion coefficients in soil and pure water, respectively) for variably compacted soils with different textures. We measured the Ds for KCl on five different soils from Japan: two volcanic ash soils (Andisols) at different bulk densities, two sandy soils, and a loamy soil. The Ds was measured across a wide range of θ using the half‐cell method. The Ds/D0 values for Andisols with bimodal pore size distribution were comparatively lower than for the other soils. Opposite to the behavior for sandy soils, the Ds/D0 for Andisols at a given θ decreased markedly with increasing bulk density under wet conditions but increased with increasing bulk density under dry conditions. Data for all soil types including sandy soils with unimodal pore size distribution implied a two‐region behavior when plotted as log(Ds/D0) vs. θ. We suggest that the similar behavior across soil types can be explained by regions of low and high water phase connectivity for relatively structureless soils and by high intraaggregate and low interaggregate water phase tortuosity for aggregated soils. Among a number of tested predictive models for Ds/D0, the Penman–Millington–Quirk model, which requires knowledge of only θ and total porosity, performed best across soil types.
The Influence of Rain Sensible Heat and Subsurface Energy Transport on the Energy Balance at the Land Surface
Authors: Kollet Stefan J. , Cvijanovic Ivana , Schüttemeyer Dirk , Maxwell Reed M. , Moene Arnold F. , Bayer Peter
Published: November 2009

In land surface models, which account for the energy balance at the land surface, subsurface heat transport is an important component that reciprocally influences ground, sensible, and latent heat fluxes and net radiation. In most models, subsurface heat transport parameterizations are commonly simplified for computational efficiency. A simplification made in all models is to disregard the sensible heat of rain, Hl, and convective subsurface heat flow, qcv, i.e., the convective transport of heat through moisture redistribution. These simplifications act to decouple heat transport from moisture transport at the land surface and in the subsurface, which is not realistic. The influence of Hl and qcv on the energy balance was studied using a coupled model that integrates a subsurface moisture and energy transport model with a land surface model of the land surface energy balance, showing that all components of the land surface energy balance depend on Hl The strength of the dependence is related to the rainfall rate and the temperature difference between the rain water and the soil surface. The rain water temperature is a parameter rarely measured in the field that introduces uncertainty in the calculations and was approximated using the either air or wet bulb temperatures in different simulations. In addition, it was shown that the lower boundary condition for closing the problem of subsurface heat transport, including convection, has strong implications on the energy balance under dynamic equilibrium conditions. Comparison with measured data from the Meteostation Haarweg, Wageningen, the Netherlands, shows good agreement and further underscores the importance of a more tightly coupled subsurface hydrology–energy balance formulation in land surface models.
Abstraction from Infiltrating Water Content Waves during Weak Viscous Flows
Authors: Hincapié Ingrid A. , Germann Peter F.
Published: November 2009

Based on observations of constant wetting front velocities throughout a depth range of 1 to 2 m, we simplify infiltration as gravity‐driven weak viscous flow. In theory, time‐limited constant infiltration generates a sharp‐crested water‐content wave, WCW, at the surface that suddenly increases the soil water content as it arrives at a particular depth. This is in contrast to the more gradual increases produced by observed WCWs. The deviation between theoretical and observed WCWs is ascribed to water abstraction from the WCW to finer soil pores due to the gradient of capillary potential, ∇ψ. Water abstraction occurs across a finite time interval. The total amount of abstraction is the difference between the WCW's maximal water content and its antecedent water content, while its time interval lasts from the first increase to steady water content. The WCWs' maximal water contents are usually below complete saturation. The wave velocity multiplied by the time interval of abstraction yields the depth increment ZA of water abstraction during the passing of the wave. The frequency distribution of 215 ZA values was deduced from WCWs that were measured in situ under sprinkler irrigation. The ZA distribution covered a range from 0.2 to about 10 m, with its 50% midpoint at about 1 m. The limited depth range of increments indicates that abstraction is also a time‐limited process that may end before the pores surrounding the WCW are completely water saturated
Implicit Subtime Stepping for Solving Nonlinear Flow Equations in an Integrated Surface–Subsurface System
Authors: Park Young-Jin , Sudicky Edward A. , Panday Sorab , Matanga George
Published: November 2009

A diverse group of problems requires quantification of the entire hydrologic cycle by the integrated simulation of water flow in the surface and subsurface regimes. In a transient integrated simulation of the water cycle, the time step size is a key factor in controlling the solution accuracy and the simulation efficiency for a given spatial discretization. In general, if the time step size is sufficiently small, the resulting solution becomes more accurate but with higher computational cost. Thus, to maintain an acceptable level of solution accuracy in the entire simulation domain, the time step size is restricted by the relatively rapid responses in the surface flow regime. As the relatively rapid responses are typically limited to a small portion of the surface domain compared with the groundwater system, a large portion of the domain tends to be temporally overdiscretized. The implicit subtime stepping approach described here can apply smaller subtime steps only to the subdomain where the accuracy requirements are needed. In this work, generalized formulations for implicit subtime stepping in the numerical solution of the nonlinear coupled surface–subsurface equations were derived and implemented into the integrated model HydroGeoSphere. Application to several problems showed that implicit subtime stepping can significantly improve the simulation efficiency with minimal loss in accuracy. The methodology was successfully applied to enhance the computational efficiency of an integrated flow simulation in the San Joaquin Valley, California, where the characteristic response time near surface drainage streams is orders of magnitude shorter than in the groundwater regime.
A Second‐Order Accurate, Finite Volume–Based, Integrated Hydrologic Modeling (FIHM) Framework for Simulation of Surface and Subsurface Flow
Authors: Kumar Mukesh , Duffy Christopher J. , Salvage Karen M.
Published: November 2009

Surface water, the vadose zone, and groundwater are linked components of a hydrologic continuum. In order to capture the interaction between different components of a hydrologic continuum and to use this understanding in water management situations, an accurate numerical model is needed. The quality of model results depends on accurate representation of the physical processes and the data describing the area of interest, as well as performance of the numerical formulation implemented. Here we present a physics‐based, distributed, fully coupled, second‐order accurate, upwind cell‐centered, constrained unstructured mesh based finite‐volume modeling framework (FIHM) that simultaneously solves two‐dimensional unsteady overland flow and three‐dimensional variably saturated subsurface flow in heterogeneous, anisotropic domains. A multidimensional linear reconstruction of the hydraulic gradients (surface and subsurface) is used to achieve second‐order accuracy. Accuracy and efficiency in raster data and vector‐boundary representations are facilitated through the use of constrained Delaunay meshes in domain discretization. The experiments presented here (i) explore the influence of initial moisture conditions, soil properties, anisotropy, and heterogeneity in determining the pressure head distributions in the vadose and saturated zones, (ii) show the existence of localized “flux rotation” phenomenon due to heterogeneous anisotropy, leading to the creation of convergence–divergence zones, (iii) show the influence of vertical drainage from unsaturated zone on the response of an unconfined aquifer to pumping, and (iv) show the effects of capillarity, saturation excess, infiltration excess, and initial water table location on determining the overland flow generation.
The Influence of Biofilm Spatial Distribution Scenarios on Hydraulic Conductivity of Unsaturated Soils
Authors: Rosenzweig Ravid , Shavit Uri , Furman Alex
Published: November 2009

The development of biofilms in unsaturated soils is likely to influence the hydraulic conductivity function. Despite its importance, this effect has received little attention. Mostafa and Van Geel (2007, Vadose Zone Journal, 6:175–185) proposed several hydraulic conductivity models that acount for the effect of bacteria in unsaturated soils. We have expanded these models by considering the change in biofilm pore‐size distribution and its effect on the entire hydraulic conductivity function. Three scenarios were considered: (i) the biofilm fills the smallest pores first; (ii) a biofilm of uniform thickness coats all pore walls; and (iii) the biofilm coats the soil with a constant volume fraction of each pore. The results show that the pore‐scale distribution of the biofilm has a significant effect on the hydraulic properties of the soil and therefore has to be accounted for when modeling flow and transport in biofilm‐affected soils.
Comparison of Data Assimilation Techniques for a Coupled Model of Surface and Subsurface Flow
Authors: Camporese Matteo , Paniconi Claudio , Putti Mario , Salandin Paolo
Published: November 2009

Data assimilation in the geophysical sciences refers to methodologies to optimally merge model predictions and observations. The ensemble Kalman filter (EnKF) is a statistical sequential data assimilation technique explicitly developed for nonlinear filtering problems. It is based on a Monte Carlo approach that approximates the conditional probability densities of the variables of interest by a finite number of randomly generated model trajectories. In Newtonian relaxation or nudging (NN), which can be viewed as a special case of the classic Kalman filter, model variables are driven toward observations by adding to the model equations a forcing term, or relaxation component, that is proportional to the difference between simulation and observation. The forcing term contains four‐dimensional weighting functions that can, ideally, incorporate prior knowledge about the characteristic scales of spatial and temporal variability of the state variable(s) being assimilated. In this study, we examined the EnKF and NN algorithms as implemented for a complex hydrologic model that simulates catchment dynamics, coupling a three‐dimensional finite element Richards' equation solver for variably saturated porous media and a finite difference diffusion wave approximation for surface water flow. We report on the retrieval performance of the two assimilation schemes for a small catchment in Belgium. The results of the comparison show that nudging, while more straightforward and less expensive computationally, is not as effective as the ensemble Kalman filter in retrieving the true system state. We discuss some of the strengths and weaknesses, both physical and numerical, of the NN and EnKF schemes.
A Quasilinear Model for Solute Transport under Unsaturated Flow
Authors: Houseworth J. E. , Leem J.
Published: November 2009

We developed an analytical solution for solute transport under steady‐state, two‐dimensional, unsaturated flow and transport conditions for the investigation of high‐level radioactive waste disposal. The two‐dimensional, unsaturated flow problem is treated using the quasilinear flow method for a system with homogeneous material properties. Dispersion is modeled as isotropic and is proportional to the effective hydraulic conductivity. This leads to a quasilinear form for the transport problem in terms of a scalar potential that is analogous to the Kirchhoff potential for quasilinear flow. The solutions for both flow and transport scalar potentials take the form of Fourier series. The particular solution given here is for two sources of flow, with one source containing a dissolved solute. The solution method may easily be extended, however, for any combination of flow and solute sources under steady‐state conditions. The analytical results for multidimensional solute transport problems, which previously could only be solved numerically, also offer an additional way to benchmark numerical solutions.
Sensitivity Analysis of Transient‐MIM HYDRUS‐1D: Case Study Related to Pesticide Fate in Soils
Authors: Cheviron Bruno , Coquet Yves
Published: November 2009

A sensitivity analysis of the HYDRUS‐1D model was performed based on scenarios that represented the fate of a nonvolatile pesticide in three soils. We used the latest dual‐porosity, transient mobile–immobile (MIM) version of HYDRUS‐1D that includes water and solute transfers between mobile and immobile domains. We considered flat bare soils under atmospheric boundary conditions with identical initial pressure head profiles. We targeted instantaneous and mean annual pesticide concentration values at 1‐m depth as relevant output variables. Reference values for most of the parameters were obtained from in situ or laboratory measurements. Automation of parameter set generation and input formatting was achieved using SENSAN. We used a one‐group‐at‐a‐time sensitivity analysis to isolate and identify the effect of single parameter variations whose ranges were potentially different between topsoil layers (Group 1) and deep layers (Group 2). Sensitivity was analyzed by calculating the time‐dependent ratio of variation, i.e., the ratio of relative variation in output concentration to relative variation in parameter input values. As found for other single‐ or dual‐ permeability models, transient‐MIM HYDRUS‐1D was highly sensitive to parameters related to pesticide degradation and sorption, especially the Freundlich exponent associated with nonlinear sorption. Variations in the parameter n of the Mualem–van Genuchten functions had also a very significant impact. Among the MIM parameters, only saturated immobile and mobile water contents were very sensitive parameters, especially those of the topsoil layers. Parameter sensitivities hardly varied among the three soils, but this could be due to their limited contrast.
Sliding mode control of dissolved oxygen in an integrated nitrogen removal process in a sequencing batch reactor (SBR)
Authors: Muñoz C. , Young H. , Antileo C. , Bornhardt C.
Published: November 2009

This paper presents a sliding mode controller (SMC) for dissolved oxygen (DO) in an integrated nitrogen removal process carried out in a suspended biomass sequencing batch reactor (SBR). The SMC performance was compared against an auto-tuning PI controller with parameters adjusted at the beginning of the batch cycle. A method for cancelling the slow DO sensor dynamics was implemented by using a first order model of the sensor. Tests in a lab-scale reactor showed that the SMC offers a better disturbance rejection capability than the auto-tuning PI controller, furthermore providing reasonable performance in a wide range of operation. Thus, SMC becomes an effective robust nonlinear tool to the DO control in this process, being also simple from a computational point of view, allowing its implementation in devices such as industrial programmable logic controllers (PLCs).
Population dynamics of nitrite oxidizers in nitrifying granules
Authors: Vázquez-Padín J. R. , Figueroa M. , Mosquera-Corral A. , Campos J. L. , Méndez R.
Published: November 2009

The competition between Nitrospira and Nitrobacter species was analyzed in this work under conditions of excess of nitrite. A population of nitrite oxidizing bacteria (NOB) was developed from nitrifying biomass grown as granules with a mean diameter of 0.8 mm, whose feed was switched from ammonium to nitrite. The initial population distribution of the granules was: 60% Nitrosomonas and 30% Nitrospira and it evolved to 45% Nitrobacter and 40% Nitrospira measured 177 days after the change in the feeding. The disappearance of Nitrosomonas allowed the development of an important population of Nitrobacter demonstrating that these organisms, characterized by being r strategists NOB, are poor competitors when oxygen is the limiting substrate. Interestingly, the physical structure of the granules was not altered by the change of its microbial composition during the 220 days of operation.
The effect of initial loading on the removal of ammonium and potassium from source-separated human urine via clinoptilolite
Authors: Beler Baykal B. , Kocaturk N. P. , Allar A. D. , Sari B.
Published: November 2009

Collection of wastewater in segregated streams is one of the new concepts in domestic wastewater management. One such stream is yellow water which is mainly human urine. Direct use of this richest fraction in terms of nutrients on plants as fertilizer is one of the recommendations as the final end use. Indirect use of urine as fertilizer may also be exercised after various modes of processing. One of those is processing with clinoptilolite to transfer plant nutrients onto the zeolite and then to recover them subsequently. One of the significant factors in this process is the initial nutrient loading with which clinoptilolite is charged. This paper aims to investigate the transfer of ammonium and potassium from source-separated urine onto clinoptilolite, concentrating upon surface concentrations attained and removal efficiencies under various initial ammonium loadings. The results have indicated that variations in initial loading have no significant effect in terms of removal efficiencies up to 10 mg NH4+/g clinoptilolite. Highly acceptable efficiencies could be attained up to 15 mg NH4+/g clinoptilolite after which the efficiency goes down as initial loading is increased. Overall, increased initial loadings result in higher final surface concentrations but decreased removal efficiencies.
Respirometric evaluation of side-stream treatment of reject water as a source of nitrifying bacteria for main-stream activated sludge bioreactors
Authors: Smith R. C. , Oerther D. B.
Published: November 2009

A laboratory-scale bioreactor study was conducted to characterize differences in nitrification function in main-stream reactors due to bioaugmentation from side-stream reactors treating reject water. The objective was to evaluate how configuration of a suspended growth side-stream bioreactor impacts nitrification function in the main-stream bioreactor. A bioaugmentation effect was not observed in main-stream reactors operated at warm temperatures. Complete oxidation of ammonia to nitrate was observed in the bioaugmented and control main-stream reactors although nitrite accumulation was observed in each case. Furthermore, respirometry did not reveal superior kinetics in bioaugmented reactors operated at warm temperatures. At cold temperatures bioaugmentation may have stabilized ammonia oxidation in main-stream reactor B2 bioaugmented from a PFR side-stream. Complete ammonia oxidation was observed for most of cold period of operation in the main-stream bioreactor B2. Furthermore, respirometry revealed a higher rate of ammonia oxidation and more stable nitrite oxidation compared with the control bioreactor.
Balancing yield, kinetics and cost for three external carbon sources used for suspended growth post-denitrification
Authors: Mokhayeri Y. , Riffat R. , Murthy S. , Bailey W. , Takacs I. , Bott C.
Published: November 2009

Facilities across North America are designing plants to meet stringent limit of technology (LOT) treatment for nitrogen removal. In the Mid-Atlantic region of the United States, this is in response to the Chesapeake Bay Agreement, which limit effluent total nitrogen discharges from wastewater treatment plants to between 3–5 mg/L. Since denitrification is crucial for the removal of nitrogen, maximizing this process step will result in a decrease in nutrient load to the receiving waters. Of particular interest is the use of an alternate external carbon source to replace the most commonly used carbon, methanol. Three external carbon sources were evaluated in this study including: methanol, ethanol and acetate at 13°C. The aim of this study was to evaluate the relative benefits and constraints for using these three carbon types. Laboratory scale Sequencing Batch Reactors (SBRs) were set up to grow and acclimate carbon free biomass to the specified substrate while in-situ Specific Denitrification Rates (SDNRs) were conducted concurrently. The results suggest that the SDNRs for acetate (31.0 ± 4.6 mgNO3-N/gVSS/hr) and ethanol (29.6 ± 5.6 mgNO3-N/gVSS/hr) are higher than that for methanol (10.1 ± 2.5 mgNO3-N/gVSS/hr). The yield coefficients in g COD/g COD were observed to follow a similar trend with values of 0.45 ± 0.05 for methanol, 0.53 ± 0.06 for ethanol and 0.66 ± 0.06 for acetate.
A framework for supporting rainwater harvesting in the UK
Authors: Ward S. , Butler D. , Barr S. , Memon F. A.
Published: November 2009

Numerous policy vehicles have been introduced in the UK promoting the use of rainwater harvesting (RWH). However, an ‘implementation deficit’ exists where legislation limits action by failing to provide adequate support mechanisms. This study uses an interdisciplinary approach to construct a framework to address the issue of overcoming this deficit. Evidence bases have identified six deficit categories, which confirm a lack of enabling of stakeholders. Outline recommendations, such as coordinated information provision and reconsideration of incentive schemes are made in relation to these categories to complete the framework for supporting RWH in the UK.
Choice of indicator organism and library size considerations for phenotypic microbial source tracking by FAME profiling
Authors: Duran Metin , Yurtsever Deniz , Dunaev Timur
Published: November 2009

The primary objective of this study was to investigate the effects of choice of the indicator organisms on the accuracy of classifying the fatty acid methyl ester (FAME) profiles of the known-source library isolates. First, a known-source library containing the FAME profiles of Enterococcus isolates cultured from six different possible sources of microbial pollution was developed. A total of 511 Enterococcus isolates were profiled: 120 isolates from sewage samples representing humans; 69 from dairy and cattle cow; 74 from chicken; 76 from swine; 94 from deer; and 78 from waterfowl. Classification of known-source Enterococcus isolates into their respective host categories resulted with a 66% average rate of correct classification (ARCC) in a six-way discriminant analysis (DA). The ARCC increased to 75% when the individual hosts were pooled into larger categories of human, livestock, and wildlife. The accuracy was 80% when isolates of human origin were discriminated against those of non-human origins. Recently, several studies reported the ARCCs for various classification schemes associated with total coliform (TC), fecal coliform (FC), and Escherichia coli of the known-source isolates. When the accuracy of classification of Enterococcus isolates was compared to those reported for TC, FC, and E. coli isolates, the lowest ARCCs were associated with classification of E. coli isolates, the only species level indicator organism among the four compared. It was found that the degree of discrimination increases as the indicator becomes more inclusive of bacteria from different genus. In addition, random cluster formation analysis indicates that known-source libraries with isolate numbers between 300 and 500 might be sufficient for MST by FAME.
Determination of odour threshold concentration ranges for some disinfectants and disinfection by-products for an Australian panel
Authors: McDonald S. , Lethorn A. , Loi C. , Joll C. , Driessen H. , Heitz A.
Published: November 2009

Taste-and-odour complaints are a leading cause of consumer dissatisfaction with drinking water. The aim of this study was to determine odour threshold concentration ranges and descriptors, using a Western Australian odour panel, for chlorine, bromine, chlorine added to bromide ions, the four major regulated trihalomethanes (THMs), and combined THMs. An odour panel was established and trained to determine odour threshold concentration ranges for odorous compounds typically found in drinking water at 25°C, using modified flavour profile analysis (FPA) techniques. Bromine and chlorine had the same odour threshold concentration ranges and were both described as having a chlorinous odour by a majority of panellists, but the odour threshold concentration range of bromine expressed in free chlorine equivalents was lower that that of chlorine. It is likely that the free chlorine equivalent residuals measured in many parts of distribution systems in Western Australia are comprised of some portion of bromine and that bromine has the potential to cause chlorinous odours at a lower free chlorine equivalent concentration than chlorine itself. In fact, bromine is the likely cause of any chlorinous odours in Western Australian distributed waters when the free chlorine equivalent concentration is between 0.04 and 0.1 mg L−1. Odour threshold concentrations for the four individual THMs ranged from 0.06–0.16 mg L−1, and the odour threshold concentration range was 0.10 ± 0.09 mg L−1 when the four THMs were combined (in equal mass concentrations). These concentrations are below the maximum guideline value for total THM concentration in Australia so odours from these compounds may possibly be observed in distributed waters. However, while the presence of THMs may contribute to any sweet/fragrant/floral and chemical/hydrocarbon odours in local drinking waters, the THMs are unlikely to contribute to chlorinous odours.
Removal and recovery of phosphate from municipal wastewaters using a polymeric anion exchanger bound with hydrated ferric oxide nanoparticles
Authors: Martin B. D. , Parsons S. A. , Jefferson B.
Published: November 2009

A new type of ion exchange media which is highly selective for phosphate, and can be easily regenerated has been investigated. The media consists of hydrated ferric oxide nanoparticles dispersed within the pore structures of polymeric anion exchanger beads. The media combines the durability and mechanical strength of ion exchange resins with the high sorption capacity of ferric oxide for phosphate. The media was trialled in fixed bed mini column experiments with real final effluent from two UK sewage treatment works, one with treatment based on chemical precipitation with iron chloride salts into an activated sludge process (population >250,000), and one based on trickling filter treatment with no specific phosphorus removal process (population <10,000). Results show that the media has high capacity for removing phosphate, reaching capacity at 4000 and 1300 bed volumes for the chemical precipitation and trickling filter works respectively, with performance greatly exceeding that of a standard anion exchanger, Amberlite IRA-410. Also trialled was the media's ability to elute the phosphorus after breakthrough, with the aim of recovering and processing it into a useful product. A one step regenerative process using a single solution containing 4% NaOH and 2% NaCl was passed through the resin bed and the phosphorus concentration of each bed volume leaving the column analysed. 80% of the phosphorus was eluted in the first bed volume. Subsequent tests investigated the performance of the media after successive partial regenerations of one bed volume of the NaOH/NaCl solution. There was no loss of performance observed after ten regeneration cycles, and levels of eluted phosphate were consistently high. These results suggest that the media has high potential for the removal and recovery of phosphate from wastewater streams. Additionally, the small volume of regenerant required translates to a very small operational footprint.
Phosphorus budget in the low-income, peri-urban area of Kibera in Nairobi (Kenya)
Authors: Kelderman P. , Koech D. K. , Gumbo B. , O'Keeffe J.
Published: November 2009

Kibera, located in Nairobi, Kenya is one of the largest (235,000 inhabitants) low-income areas in East Africa. Surface waters in Kibera show high pollution levels with respect to SRP (soluble reactive phosphorus; range: 2–10 mg P/L), coming from the uncontrolled wastewater discharges in the area. The different P production and consumption values in Kibera were estimated using interviews (155 interviewed) as well as detailed P house-keeping for five representative families. The results show that highest P consumption comes from food, in particular cereals. Highest P production came from urine (55% of the total) and faeces (31%), with relatively lower contributions from grey water and solid wastes. The overall P budget in Kibera amounted to around 9 × 103 kg P/month. This is equivalent to 0.47 g P/person yr, both for P production and consumption, with a relative error of 20%. Comparing with the estimated P outflows via the Kibera surface waters, around 65% of the P produced in Kibera will leave the area. In future ECOSAN techniques such as urine separation could well be applied for efficient recycling of these waste sources.
Comment on Samuelson: Broad Public Access is Worth Some Risk
Authors: Courant Paul N
Published: November 2009

Paul Courant agrees with Pamela Samuelson that the Google settlement is less than perfect, but he argues that it is far better than nothing, which he sees as the likely alternative.
Lord of the Rings Impact on Federal and State Film Industry Tax Incentives and Their Tax Treatment
Authors: Wright Kathleen K. , Karlinsky Stewart S. , Tarantino Kim A.
Published: November 2009

ABSTRACT: This article discusses recent developments for both federal and state tax purposes that directly impact the entertainment industry. For federal purposes, Congress has recently expanded the scope of the Section 181 and 199 deductions to allow more generous deductions, and in the case of Section 199 to relax the requirements which must be met to claim the deduction. The states seem to be in competition to “outdo” each other in enacting rebates or transferable credits to enhance the desirability of their states for film production. The tax treatment of these credits for both federal and state purposes is discussed, and the Appendix summarizes the provisions of these incentives on a state-by-state basis. The article concludes with a discussion of the effectiveness of this type of incentive legislation.
The Variety of Information Transfer in Animal Sonic Communication: Review from a Physics Perspective
Authors: Fletcher Neville  H.
Published: November 2009

For many anatomical and physical reasons animals of different genera use widely different communication strategies. While some are chemical or visual, the most common involve sound or vibration and these signals can carry a large amount of information over long distances. The acoustic signal varies greatly from one genus to another depending upon animal size, anatomy, physiology, and habitat, as also does the way in which information is encoded in the signal, but some general principles can be elucidated showing the possibilities and limitations for information transfer. Cases discussed range from insects through song birds to humans.