bluuebunny/crossref_metadata_2025 huggingface dataset:
XAG: a tool in the design improvement of power plants
Authors: Roy-Aikins J. E A.
Published: September 2006

A computer program XAG has been developed for aiding the design of arbitrary thermal power plants. It is the third in a series of software developed for evaluating the thermo-dynamic and economic performances of power plants operating on the Brayton and/or Rankine cycle. The mechanics of operation of XAG is described in this article and the use of the software is illustrated in the design improvement of a turbo fuel cell. The tenets on which the software was developed are that power plants must be designed for minimum cost of plant product(s) and that this minimum cost must occur at a performance level that is practical and which reflects the state of the art. It is necessary, therefore, that the analysis of plant performance be carried out on an exergy basis and that the optimization be conducted on a thermoeconomic basis. The results of the analysis of the turbo fuel cell show that the cost attributable to the fuel cell was primarily due to capital cost, whereas that attributable to the gas turboset was due primarily to exergy destruction in the components of the gas turbine. It was concluded that research efforts should be directed at reducing the capital cost of fuel cells to make the technology competitive.
Development of a thermal power plant simulation tool based on object orientation
Authors: Shirakawa M
Published: September 2006

This study presents a new dynamic simulation tool that facilitates plant and control system design of thermal power plants. In order to provide flexibility in building plant and control systems, object-oriented modelling techniques are used to model individual plant components, and each component object model is based on the verified first principles model. Further, simulation models can be easily built by connecting individual component object models, similar to the procedure adopted in an actual plant, by using a user-friendly graphical user interface. This tool enables the design engineer to build a simulation model, execute the simulation during the design process, test an actual plant control system, and adjust the control parameters. It is a useful design tool that accelerates and enhances the plant and control system design process.
Non-contact blade vibration measurement analysis using a multi-degree-of-freedom model
Authors: Schlagwein G , Schaber U
Published: September 2006

The non-contact blade vibration measurement technique (tip timing) has been developed in the 1970s with focus on large steam turbine blades. Today, most of the turbo machine manufacturers are using tip timing for vibration amplitude or frequency evaluation of rotating blades. Different analysing methods have been developed. The most common method is a time domain analysis of a resonance passing using one- or two-blade sensors and a 1/rev sensor on the shaft. Normally, this analysing method is based on a single-degree-of-freedom resonator model. For mistuned blade rows, a single-degree-of-freedom model is not suitable. The possible errors of the single-degree-of-freedom model were repeatedly investigated. In this article, a multi-degree-of-freedom evaluation method is presented in detail. For the first time, a successful application on measurement data is reported.
Comparison of performance of compressed-air energy-storage plant with compressed-air storage with humidification
Authors: Najjar Y. S H. , Jubeh N. M.
Published: September 2006

In this work, the use of compressed-air storage with humidification (CASH) system, instead of using the compressed-air energy storage (CAES) system, to increase the generated power ( Wgen) and primary energy efficiency (ηpe) is discussed. Performance is calculated for CAES and CASH systems. The operating variables in this study are discharged air mass flow (mt), ambient air temperature ( Ta), and overall pressure ratio (Rc). The effect of these variables on the generated power ( Wgen), energy ratio (ER), and primary energy efficiency (ηpe) is evaluated. The efficiencies are based on lower heating value.

The result showed superior performance of CASH system relative to CAES. For example, at mt= 200 kg/s, Wgen= 243.029 MW, ER = 45.41 per cent, ηpe= 43.2 per cent for the CAES; whereas for the CASH system, Wgen= 277.083 MW, ER = 39.8 per cent, ηpe= 47.1 per cent.

The generated power ( Wgen), energy ratio (ER), and primary energy efficiency (ηpe) for the CASH system at the design point, are about 14 per cent more, 14 per cent less, and 9 per cent more than that for the CAES system, respectively.
Life cycle assessment of a medium-sized photovoltaic facility at a high latitude location
Authors: Muneer T , Younes S , Lambert N , Kubie J
Published: September 2006

Performance of a 160 m2photovoltaic installation at the Napier University's Merchiston Campus, situated 3 km from Edinburgh's city centre, is presented. The alternative current and direct current electrical outputs were recorded since the installation of the facility was completed in April 2005. An analysis of the efficiency of the facility, as well as energetic, environmental, and monetary life cycle assessments, using long-term meteorological data is presented in this article.
Study of tip clearance effects in centrifugal fans with unshrouded impellers using computational fluid dynamics
Authors: Engin T
Published: September 2006

Performance of centrifugal fans with unshrouded impellers strongly depends upon complex configuration of the asymmetrical flowfield in the axial direction, which is highly unsteady. The flowfield, in turn, is considerably affected by the design parameters of both scroll and impeller geometry, for which tip clearance is of particular interest. This article presents a three-dimensional computational fluid dynamics (CFD) simulation of the flowfield in three different unshrouded centrifugal fan impellers with varying tip clearances. A commercial CFD code, namely, Fluent V6.2.16 with a k-ɛ two-equation turbulence model was utilized in order to study the effects of tip clearance on the overall performance of each fan with the tip clearances ranging from 5 to 30 mm. The numerical results were compared with the experimental data reported previously in the literature by the present author and his colleagues, and excellent agreements were observed for each fan.
Hollow Fiber Membrane as a Low-cost and High-efficient Micromixer to Prepare CdS Nanoparticles
Authors: Wang Hongzhi , Wei Jie , Yu Muhuo , Li Yaogang , Sun Junfen , Zhu Meifang
Published: September 2006

Hollow fiber membrane was utilized to act as a new kind of micromixer. By controlling the nitrogen pressure, external reactant could quickly mix with the fluid in the fiber channel through the nanopores located on the wall of hollow fiber membrane. CdS nanoparticles with narrow size distribution have been produced in this microreactor system owing to the efficient mixing.
Hydroalkenylation of Alkynes Catalyzed by Dinuclear Palladium Complexes via C–H Bond Activation
Authors: Tsukada Naofumi , Setoguchi Hiroyuki , Mitsuboshi Tomohiro , Inoue Yoshio
Published: September 2006

Hydroalkenylation of alkynes with alkenes proceeded in the presence of dinuclear palladium complexes and lithium tri-tert-butoxyaluminum hydride to yield 1,3-dienes.
Platinum-free Catalyst for Efficient Reduction of Oxygen at Air Cathode
Authors: Sawai Keijiro , Uda Daisaku
Published: September 2006

Electrocatalytic activity and selectivity for oxygen reduction to water on platinum-free catalysts prepared from transition metal hexacyanometallate precursors have been examined using a rotating ring-disk electrode technique. The results obtained indicated that a catalyst containing copper and iron promotes so-called four-electron reduction reaction of oxygen at a potential close to or higher than that of a Pt electrode, so that it could be a possible candidate substituting for Pt-based catalysts of air cathodes.
Fluorescent Molecular Sensing for Various Types of Surfactants Using Amino-β-cyclodextrins Bearing Naphthalene Chromophore
Authors: Nakashima Hironori , Yoshida Noboru
Published: September 2006

Fluorescent spectroscopic studies on the complexation of naphthalene-appended amino-β-cyclodextrins, 1 and 2, with anionic, cationic, and nonionic surfactants have been carried out. In host 1–surfactant system, an excellent fluorescent signal change was observed. On the other hand, host 2 exhibits no photophysical response in the presence of various surfactants. The difference in the properties between 1 and 2 was interpreted by difference in the inclusion depth of the naphthalene units for the cyclodextrin cavity. The binding abilities and thermodynamic (ΔH°, ΔS°, and ΔG°) quantities of 1–surfactant system have been discussed to characterize structure/enegetics for the complexation process.
Immobilization of a Binuclear Ruthenium(III) Complex on a Gold (111) Surface: Observations of Proton-coupled Electron Transfer and Electrochemical Durability in Aqueous Media
Authors: Uehara Hiromitsu , Abe Masaaki , Hisaeda Yoshio , Uosaki Kohei , Sasaki Yoichi
Published: September 2006

An oxo-bridged diruthenium(III) complex was immobilized on a Au(111) electrode through the coordination by terminal pyridyl groups of self-assembled monolayer of alkyl chains, and the immobilized complex underwent proton-coupled electron-transfer reactions in a very wide pH range (2–12) with remarkable monolayer durability for multiple potential cycles.
The diffusion of a medical innovation: Where teleradiology is and where it is going
Authors: Dimmick Susan L , Ignatova Kunka D
Published: September 2006

Teleradiology is one of the more successful applications of telemedicine as measured by a bibliometric analysis of teleradiology research publications. The organizational diffusion of innovation framework is helpful in understanding the diffusion of teleradiology. Teleradiology had become part of the practices of two-thirds of radiologists who responded to the American College of Radiology survey in 1999. It is clear that teleradiology has become routinized even though quantitative data are hard to find. Telecardiology may be the next successfully diffused form of telemedicine. The potential cloud on the horizon for telediagnostics is political pressure to avoid outsourcing to foreign countries, particularly those to which US information technology jobs have already been transferred. How the outsourcing issue is resolved will have a significant effect on teleradiology specifically, and, perhaps, telemedicine generally.
Alternatives to randomized controlled trials in telemedicine
Authors: Grigsby Jim , Bennett Rachael E
Published: September 2006

Research designs other than true experiments may be useful in the evaluation of telemedicine. Potential methods include those that do not rely on randomization and tight control of the intervention, and analysis of existing administrative and clinical databases. Quasi-experimental designs may also be useful, especially when conducted in association with careful statistical methods that allow the investigator to control for certain differences between groups. Databases, such as those maintained by the Centers for Medicare and Medicaid Services, contain information on both outcomes and claims, as well as disease/procedure registries and electronic health records. This may provide a potential tool for understanding the effects of telemedicine on access to care in conjunction with costs and quality. These different approaches have advantages and disadvantages, but may be useful in telemedicine, where the conduct of randomized controlled trials is generally very expensive and frequently not feasible.
The role of telemedicine in fostering health-care innovations to address problems of access, specialty shortages and changing patient care needs
Authors: Rheuban Karen S
Published: September 2006

The integration of advanced technologies into health-care services promises to aid society in its transition to a coordinated, systems approach which is focused on disease prevention, enhanced wellness, chronic disease management, decision support, quality and patient safety. By incorporating such technologies, clinicians will be able to manage the growing volumes of medical information, research and decision support analytical tools. The deployment of advanced technologies will minimize the barriers of distance and geography to enhance access and facilitate the delivery of integrated health care. This will support and enhance the goals of the US federal Healthy People 2010 initiative.
Will we see data repositories for telehealth activity in the near future?
Authors: Whitten Pamela
Published: September 2006

Policy-makers and researchers lament the absence of telehealth registries to enhance knowledge regarding outcomes and efficacy of telehealth interventions. A number of different organizations operate registries, but there do not appear to be any true telehealth registries. One reason is that federal requirements through such policies as the Health Insurance Portability and Accountability Act (HIPAA) have led to heightened fear of inadvertently releasing confidential or unauthorized information. Also, it would be more efficient if patient data were captured electronically at the local level, ideally through electronic medical records (EMRs), and then transferred electronically to registries. However, the diffusion of EMRs at the local level is in its infancy. As a result, it is unlikely that we will see a comprehensive telehealth data repository within the next decade.
A Colorectal Cancer Patient Focus Group Develops an Information Package
Authors: Carney L , Jones L , Braddon F , Pullyblank AM , Dixon AR
Published: September 2006

INTRODUCTION

In order to deliver high quality care and empower cancer patients in decision-making, good quality information and communication are essential. We describe the development of an information booklet.

PATIENTS AND METHODS

A total of 22 colorectal cancer patients (12 male; median age, 72 years, range, 40–86 years) met on 3 occasions. Patients were asked to define their information needs and score them (1–4) according to importance. The information document was written. The second meeting involved feedback on the booklet. The modified booklet was reviewed/approved by the group before submission for local ethics committee approval prior to its distribution to other patients.

RESULTS

All participants felt the project a good idea. Essential information included the surgeon's individual morbidity, mortality, survival, recurrence data and details of adjuvant therapies (score = 4). Also important were type of surgery, complications and postoperative recovery (score = 3). Simple anatomical drawings were also considered important.

CONCLUSIONS

The booklet is now used to personalise information for all our patients and serves, in part, as a record of the key issues discussed during the consultation. The booklet has been evaluated in a randomised trial.
Comfort Assessment of Personal Protection Systems During Total Joint Arthroplasty Using a Novel Multidimensional Evaluation Tool
Authors: Malik MHA , Handford Elizabeth , Staniford Elaine , Gambhir AK , Kay PR
Published: September 2006

INTRODUCTION

A number of studies have assessed the usefulness of surgical gowns and exhaust suits with regards to barrier function and protection afforded to healthcare workers from blood strike-through, splashes and aerosols.

PATIENTS AND METHODS

We have performed a comfort assessment comparison between the Charnley exhaust suit, disposable gown plus visor and the Stryker Steri-Shield system using a newly developed objective multidimensional ergonomic tool designed to measure wearable comfort across the dimensions of emotion, attachment, harm, perceived change, movement and anxiety.

RESULTS

The total mean Comfort Rating Scale value for a disposable gown plus visor was 16.1 with a mean dimensional score of 2.7 (range, 0.2–8.4), for the Charnley system the values were 51.4 and 8.6 (range, 5.9–12.8), respectively, and for the Stryker Steri-Shield 15.4 and 2.6 (range, 0.8–5.6).

CONCLUSIONS

The Steri-Shield system provides the least variation in comfort and, as such, may offer the best combination of comfort, protective qualities and form or style of personal protection equipment for lower limb arthroplasty operations.
Variations in Consenting Practice for Laparoscopic Cholecystectomy
Authors: Chen AM , Leff DR , Simpson J , Chadwick SJD , McDonald PJ
Published: September 2006

INTRODUCTION

To compare the variations in consenting practice amongst trainees and consultant surgeons for laparoscopic cholecystectomy with specific reference to the documentation of significant risks of surgery.

PATIENTS AND METHODS

A proforma was devised which included significant and/or commonly recognised complications of laparoscopic cholecystectomy. This was then cross-referenced with the consent forms for the 80 patients included in the study and the documented risks explained in each case were noted.

RESULTS

The results showed that there is considerable variation between the three grades of clinicians involved in obtaining a patient's consent for laparoscopic cholecystectomy. There was a clear difference in emphasis of the significant complications depending on the seniority of the consenter. Over 80% of the consents in this study were still being obtained by junior staff.

CONCLUSIONS

More often than not, patients are not provided with consistent information to make an informed choice. We suggest that a preprinted consent form will provide a more uniform approach to consenting practice for laparoscopic cholecystectomy.
Urethral Dilatation in Women: Urologists' Practice Patterns in the UK
Authors: Masarani M , Willis RG
Published: September 2006

INTRODUCTION

Review of the literature reveals little evidence to prove the efficacy of urethral dilatation for adult women with various lower urinary tract complaints. We conducted a postal survey to ascertain the actual practice of urethral dilatation among urologists in the UK.

MATERIALS AND METHODS

A questionnaire was mailed to 428 consultant urologists listed as full members of the British Association of Urological Surgeons. The questionnaire consisted of 8 items about urologists' perception of indications, efficacy, and the need for repeated dilatation and anaesthesia.

RESULTS

The questionnaire response rate was 42%. Although urethral stenosis was the most common indication (97%), the majority of urologists (69%) indicated that fewer than 25% of patients had evidence of stenosis. Overall, 61% of urologists performed dilatation 7 times or more during the last year and 55% believed that less than half of the patients experienced long-term improvement.

CONCLUSIONS

Despite the lack of strong evidence to support the use of urethral dilatation in women, many urologists continue to find it a useful tool in approaching women with lower urinary tract complaints.
Secondary Prevention of Fragility Fractures: Are We Following the Guidelines?
Authors: Prasad N , Sunderamoorthy D , Martin J , Murray JM
Published: September 2006

INTRODUCTION

The aim of this study was to determine whether orthopaedic surgeons follow the British Orthopaedic Association (BOA) guidelines for secondary prevention of fragility fractures.

PATIENTS AND METHODS

A retrospective audit was conducted on patients with neck of femur fractures treated in our hospital between October and November 2003. A re-audit was conducted during the period August to October 2004.

RESULTS

There were 27 patients in the initial study period. Twenty-six patients (96%)had full blood count measured with LFT and bone-profile measured in 18 patients (66%). Only nine patients (30%)had treatment for osteoporosis (calcium and vitamin D). Only one patient was referred for DEXA scan. Steps were taken in the form of creating better awareness among the junior doctors and nurse practitioners of the BOA guidelines. In patients above 80 years of age, it was decided to use abbreviated mental score above 7 as a clinical criteria for DEXA referral. A hospital protocol based on BOA guidelines was made. A re-audit was conducted during the period August to October 2004. There were 37 patients. All had their full blood count and renal profile checked (100%). The bone-profile was measured in 28 (75.7%) and LFT in 34 (91.9%)patients. Twenty-four patients (65%) received treatment in the form of calcium + vitamin D (20) and bisphosphonate (4). DEXA-scan referral was not indicated in 14 patients as 4 were already on bisphosphonates and for 10 patients their abbreviated mental score was less than 7. Among the remaining 23 patients, 9 patients (40%) were referred for DEXA scan. This improvement is statistically significant (P = 0.03, chi square test).

DISCUSSION AND CONCLUSIONS

The re-audit shows that, although there is an improvement in the situation, we are still below the standards of secondary prevention of fragility fractures with 60% of femoral fragility fracture patients not being referred for DEXA scan. A pathway lead by a fracture liaison nurse dedicated to osteoporotic fracture patients should improve the situation.
Forgotten Digital Tourniquet: Salvage of an Ischaemic Finger by Application of Medicinal Leeches
Authors: Durrant C , Townley WA , Ramkumar S , Khoo CTK
Published: September 2006

Individual finger tourniquets are appropriate to the management of a wide range of conditions presenting to an accident and emergency department. They are simpler and more comfortable to use than upper arm pneumatic tourniquets and commercially available digital tourniquets are not readily available in the accident and emergency unit. However, if a finger tourniquet is overlooked, ischaemia of the digit results, and gangrene may follow if the problem is not defused early enough, leading to potential disaster. 1 – 3 We present one case where a digit was salvaged after 4 days of tourniquet application, using medicinal leeches.
Soluble Interleukin 2 Receptor Levels, Temperament and Character in Formerly Depressed Suicide Attempters Compared with Normal Controls
Authors: Rothenhäusler Hans‐Bernd , Stepan Alexandra , Kapfhammer Hans‐Peter
Published: September 2006

An imbalance of the immune system and mixed personality profiles in suicide attempters have been reported. As suicidal behavior is common in patients with psychiatric disorders within the spectrum of depressive features, in this study we measured soluble interleukin‐2 receptor concentrations in plasma (sIL‐2R) and investigated temperament and character profile and their potential correlation in formerly depressed patients with a history of suicide attempt. We studied sIL‐2R levels in plasma and personality characteristics (using Cloninger's Temperament and Character Inventory [TCI]) of formerly depressed patients who had attempted suicide a mean of 3 years previously (n = 25), and age and gender matched normal controls (n = 25). There was no significant difference in sIL‐2R levels between formerly depressed suicide attempters and age and gender matched normal controls (0.23 ng/ml ± 0.25 vs. 0.19 ng/ml ± 0.16). When compared to normal controls, suicide attempt patients had a significantly higher score on the temperament dimension “harm avoidance” and a lower score on the character dimension “self‐directedness.” No significant correlation was found between sIL‐2R values and TCI dimensions. We propose that the liability to suicidal behavior among suicide attempters susceptible to depressive symptomatology may be related to high harm avoidance and low self‐directedness.
Comparison of Larval Sea Lamprey Life History Characteristics in a Lampricide‐Treated Tributary and Untreated Tributary System of Lake Champlain
Authors: Zerrenner Adam , Marsden J. Ellen
Published: September 2006

Control of sea lampreys Petromyzon marinus in Lake Champlain and the Laurentian Great Lakes is dependent primarily on selective lampricides that reduce the density of sea lamprey larvae in tributary streams. After lampricide treatment, recolonized larval sea lampreys may experience enhanced growth from density‐dependent factors, which may lead to transformation at a larger size and younger age than would have occurred before treatment. In this study, the effects of lampricide treatments on larval sea lamprey life history characteristics were compared between Lewis Creek (Vermont), a treated stream, at 4–5 years posttreatment and the untreated Pike River–Morpion Stream system (Quebec, Canada). Sea lamprey habitat was measured in each stream at approximately 100 randomly selected transects, and larval density was determined using a backpack electrofishing unit during 1999 and 2000. Larval sea lamprey density was approximately threefold higher in Lewis Creek than in the Pike River and Morpion Stream in both years. Growth measured in length and weight indicated that neither treatment nor low density created conditions for faster growth. During 1999, transformers were, on average, shorter and younger in Lewis Creek (131 mm; 100% age 4) than in the Pike River–Morpion Stream (143 mm; 100% age 5). During 2000, the majority (75%) of transformers were age 5 in all streams. Weights of age‐4 transformers in Lewis Creek (1999 and 2000) and the Pike River (2000) were higher than those of age‐4 ammocoetes in those streams. Our results suggest that the first year‐class to become reestablished after lampricide application may transform at a younger age and smaller size than fish of the same age‐class in an untreated stream. Treatment intervals must adapt to changes in age at transformation to prevent transformers from leaving Lake Champlain and Great Lakes tributaries.
Sorption of Atmospheric Ammonia by Soil and Perennial Grass Downwind From Two Large Cattle Feedlots
Authors: Hao Xiying , Chang Chi , Janzen H. Henry , Clayton George , Hill Brett R.
Published: September 2006

Livestock manure in feedlots releases ammonia (NH3), which can be sorbed by nearby soil and plants. Ammonia sorption by soil and its effects on soil and perennial grass N contents downwind from two large cattle feedlots in Alberta, Canada were investigated from June to October 2002. Atmospheric NH3 sorption was measured weekly by exposing air‐dried soil at sampling points downwind along 1700‐m transects. The amount of NH3 sorbed by soil was 2.60 to 3.16 kg N ha−1 wk−1 near the source, declining to about 0.25 kg N ha−1 wk−1 1700 m downwind, reflecting diminishing atmospheric NH3 concentrations. Ammonia sorption at a control site away from NH3 sources was much lower: 0.085 kg N ha−1 wk−1 Based on these rates, about 19% of emitted NH3 is sorbed by soil within 1700 m downwind of feedlots. Field soil and grass samples from the transect lines were analyzed for total N (TN) and KCl‐extractable N content (soil only). Nitrate N content in field soil followed a trend similar to that of atmospheric NH3 sorption. Soil TN contents, because of high background levels, showed no clear pattern. The TN content of grass, downwind of the newer feedlot, followed a pattern similar to that of NH3 sorption; downwind of the older feedlot, grass TN was correlated to soil TN. Our results suggest that atmospheric NH3 from livestock operations can contribute N to local soil and vegetation, and may need to be considered when determining fertilizer rates and assessing environmental impact.
Metal Distribution and Stability in Constructed Wetland Sediment
Authors: Knox Anna Sophia , Paller Michael H. , Nelson Eric A. , Specht Winona L. , Halverson Nancy V. , Gladden John B.
Published: September 2006

The A‐01 wetland treatment system (WTS) is a surface flow wetland planted with giant bulrush [Schoenoplectus californicus (C.A. Mey.) Palla] that is designed to remove Cu and other metals from the A‐01 National Pollution Discharge Elimination System (NPDES) effluent at the Savannah River Site near Aiken, SC. Copper, Zn, and Pb concentrations in water were usually reduced 60 to 80% by passage through the treatment system. The Cu concentrations in the wetland sediments increased from about 4 to 205 and 796 mg kg−1, respectively, in the organic and floc sediment layers in cell 4A over a 5‐yr period. Metal concentrations were higher in the two top layers of sediment (i.e., the floc and organic layers) than in the deeper inorganic layers. Sequential extraction was used to evaluate remobilization and retention of Cu, Pb, Zn, Mn, and Fe in the wetland sediment. Metal remobilization was determined by the potentially mobile fraction (PMF) and metal retention by the recalcitrant factor (RF). The PMF values were high in the floc layer but comparatively low in the organic and inorganic layers. High RF values for Cu, Zn, and Pb in the organic and inorganic layers indicated that these metals were strongly bound in the sediment. The RF values for Mn were lower than for the other elements especially in the floc layer, indicating low retention or binding capacity. Retention of contaminants was also evaluated by distribution coefficient (Kd) values. Distribution coefficient (Kd) values were lower for Cu and Zn than for Pb, indicating a smaller exchangeable fraction for Pb.
Optimization of Biofiltration for Odor Control: Model Development and Parameter Sensitivity
Authors: Li Hebi , Crittenden John C. , Mihelcic James R. , Hautakangas Hannu
Published: September 2006

A dynamic model that describes the mass transport and attenuation of odor‐causing air emissions (i.e., hydrogen sulfide and other reduced sulfur compounds) in a biofiltration unit was developed and incorporated into a software package called Biofilter™. Mechanisms included advective flow, mass transfer from the bulk phase to the biofilm, biofilm internal diffusion, and biological reaction in the biofilm. A dimensionless analysis revealed that the mass transport and attenuation of target compounds can be characterized by several dimensionless groups. Model equations were converted to ordinary differential equations using orthogonal collocation and the resulting ordinary differential equations were solved using the DGEAR algorithm. Numerical solutions were verified by comparing model simulations to analytical solutions. The model simulations showed that the existence of a water layer surrounding the biofilm in a biofiltration unit lowers the removal efficiency of hydrogen sulfide. A sensitivity analysis of model parameters (including the film transfer coefficient, biofilm diffusivity, biofilm thickness, maximum specific biomass growth rate, yield coefficient, half‐saturation coefficient, and initial active biomass concentration) using data from two biofilters located at the Cedar Rapids (Iowa) Water Pollution Control Facilities, showed that biofilm internal diffusion and biofilm kinetics have a significant effect on hydrogen sulfide removal, while external mass transfer has little effect.
Optimization of Biofiltration for Odor Control: Model Calibration, Validation, and Applications
Authors: Martin Ronald W. , Li Hebi , Mihelcic James R. , Crittenden John C. , Lueking Donald R. , Hatch Christopher R. , Ball Patrick
Published: September 2006

A dynamic model that describes the biofiltration process for hydrogen sulfide removal from wastewater treatment plant air emissions was calibrated and validated using pilot‐ and full‐scale biofilter data obtained from the Cedar Rapids (Iowa) Water Pollution Control Facilities. After calibration, the model was found to predict the dynamic effluent concentrations of the pilot‐ and full‐scale biofilters well, with the measured data falling within 58 to 80% of the model output values. In addition, the model predicted the trend of the field data, even under field conditions of changing input concentration and at effluent concentrations below 1 ppm by volume. The model demonstrated that increasing gas residence time and temperature and decreasing influent concentration decreases effluent concentration. In addition, model simulations showed that a longer residence time is required to treat dynamic loading increases, indicating that biofilter design should account for the maximum influent concentration. These results can be used to help design and operate biofilters for controlling odorous and hazardous air emissions.
Association of Urban Runoff with Coastal Water Quality in Orange County, California
Authors: Dwight Ryan H. , Semenza Jan C. , Baker Dean B. , Olson Betty H.
Published: September 2006

The associations between storm events, urban runoff, and coastal water quality have not been well investigated. A temporal and spatial analysis of 2 years of data was conducted to determine associations between urban river discharge and indicator bacteria levels for Southern California beaches and evaluate the contribution of anomalous precipitation to the association. Data show beaches next to rivers had the highest bacterial levels in both wet and dry seasons. Bacterial levels rose substantially across all sites during wet months, and river discharge and bacterial levels were all highest during the winter with the most rainfall. Precipitation was significantly associated (Spearman rank bivariate correlation, P < 0.01) with water discharged from the rivers. River discharge was significantly associated with bacterial levels at 20 out of 22 beaches, with the strongest associations at sites next to rivers. The results indicate that urban river discharge is a primary source of Southern California's coastal water pollution and, as a result, swimming at beaches near rivers may pose a significant public health risk. The strong association found between precipitation and water pollution may be relevant to studies of potential health effects associated with climate change.
Evaluation of Colilert and Enterolert Defined Substrate Methodology for Wastewater Applications
Authors: Yakub Gary P. , Castric David A. , Stadterman‐Knauer Kathleen L. , Tobin Michael J. , Blazina Mary , Heineman Tracey N. , Yee Gim Y. , Frazier Lanie
Published: September 2006

This study evaluated the utility of defined substrate methodology (DSM) for the enumeration of indicator bacteria in wastewater applications. Two commercial products, Colilert and Enterolert systems (Idexx Laboratories, Westbrook, Maine), were evaluated for variation, false‐positive results, and method correlation in both surface waters and treated wastewater effluent. The DSM tests performed as well or better than the traditional methodology. The Colilert total coliform test was also evaluated for its utility in estimating fecal coliforms by incubation at 44.5 ± 0.2 °C. The modified DSM total coliform test correlated well to membrane filtration (Pearson correlation coefficient 0.8) for two different sample groups, demonstrating its utility as a screening tool to estimate fecal coliform densities.
Removal of Solids and Oxygen Demand from Aquaculture Wastewater with a Constructed Wetland System in the Start‐Up Phase
Authors: Lin Ying‐Feng , Jing Shuh‐Ren , Lee Der‐Yuan , Wang Tze‐Wen
Published: September 2006

A pilot‐scale, constructed wetland system consisting of a free water surface (FWS) and a subsurface flow (SF) wetland operated in series was set up for treating aquaculture farm wastewater. This study examined the system start‐up phenomena and evaluated its performance in removing suspended solids, algae, and chemical oxygen demand (COD) under various hydraulic loading rates (1.8 to13.5 cm/d). The SF wetland achieved stable effluent qualities without an adaptation period, while the FWS wetland required approximately 5 months to reach consistent removal levels for suspended solids and algae. Macrophyte density was a critical factor affecting the reduction of suspended solids and chlorophyll for the FWS wetland, but not for the SF wetland. Suspended solids removals in both of the wetlands and the combined system (47 to 86%) decreased significantly as the hydraulic loading rate increased, strongly following the first‐order mass‐decrease equation. Phytoplankton solids (biomass and detritus) were a primary source of suspended solids in the aquaculture wastewater. Both chlorophyll reduction (76 to 95%) and COD removal (25 to 55%) in the constructed wetland system were apparently not affected by hydraulic loading. While algae died out because of limited sunlight in both wetlands, algae detritus probably still contributed fine particles that were difficult to remove from the water by either filtering or settling out. Removed suspended solids did not result in the increase of COD and nutrients, indicating that further solids stabilization occurred in the wetland system.
Zero‐Valent Iron Pretreatment for Enhancing the Biodegradability of Azo Dyes
Authors: Perey Jennie R. , Chiu Pei C. , Huang Chin‐Pao , Cha Daniel K.
Published: September 2006

Azo dyes are a group of chemicals that are largely resistant to aerobic biodegradation and persist in wastewater treatment processes. This study proposed that zero‐valent iron can be used to reduce the azo bond, cleaving the dye molecule into products that are more amenable to mineralization by bacteria in biological treatment processes such as activated sludge. Batch anaerobic reduction experiments were performed using two azo dyes, orange G and orange II, to determine reaction kinetics and to identify reduction products. Iron‐treated dye solutions were subjected to batch biodegradation tests and respirometric analyses to screen for enhanced biodegradability over parent dyes. Results indicate that treatment of orange G and orange II with scrap iron produces aniline and sulfanilic acid as significant products that are degraded by an acclimated culture within 24 hours. Respirometric data illustrated that iron‐treated dye solutions exert a significantly higher biochemical oxygen demand than the solutions containing orange G and orange II, demonstrating that recalcitrant azo dyes can be aerobically biodegraded after iron pretreatment.
The Role of Kaolin Particles in the Performance of a Carbamate‐Based Biocide for Water Bacterial Control
Authors: Pereira Maria Olivia , Vieira Maria João , Melo Luis F.
Published: September 2006

The influence of kaolin particles on the activity of Pseudomonas fluorescens and on the efficacy of a carbamate‐based biocide was investigated. The results indicated that kaolin particles stimulated the activity of the bacteria for all buffered pH values studied (5, 7, and 9); this effect being more evident for the tests carried out at pH 5 and 9. The presence of the clay in P. fluorescens suspensions decreased the efficiency of disinfection of the carbamate. The results also showed that kaolin was very effective in removing carbamate from the culture media. Therefore, the biocide concentration in the solution decreased, and consequently its availability to the bacteria was reduced. The results could be explained by the interaction between kaolin particles and carbamate and by the changes in the configuration of kaolin aggregates, depending on the pH value.
Long‐Term Effect of Total Cycle Time and Aerobic/Anoxic Phase Ratio on Nitrogen Removal in a Sequencing Batch Reactor
Authors: Katsogiannis A. N. , Kornaros M. , Lyberatos G.
Published: September 2006

A laboratory‐scale sequencing batch reactor was used to study nitrogen removal from a synthetic wastewater with an ammonium‐nitrogen concentration of 50 mg/L. The effect of two key parameters (i.e., the total cycle time and the aerobic/anoxic phase duration ratio) on the performance of the reactor was investigated. Four sets of operational parameters resulting from the combination of 6 and 8 hours of cycle time and 1:1 and 1:3 aerobic/anoxic ratios were studied. Denitrification was based mainly on endogenous carbon sources as long as organic carbon, provided in the form of acetate, was quickly removed from the mixed liquor during the aerobic phase of the reactor operation. In terms of nitrogen removal efficiency, the set of 8 hours of cycle time and 1:3 aerobic/anoxic phase ratio was found to be superior in that it consistently yielded an effluent total nitrogen concentration of less than 15 mg/L (consisting almost exclusively of nitrate‐nitrogen) and exhibited a percentage nitrogen removal rate of 77 ± 2.5%. In terms of wastewater throughput (i.e., wastewater volume treated per day), however, the implementation of 6 hours of cycle time and 1:3 aerobic/anoxic phase ratio was satisfactory for nitrogen removal efficiency (72 ± 2%), although elevated amounts of ammonium‐ and nitrite‐nitrogen were found in the effluent. It was also demonstrated that under certain operating conditions nitrogen removal via nitrite is observed, as nitratification (i.e., oxidation of nitrite‐nitrogen to nitrate) and denitratification (i.e., reduction of nitrate‐nitrogen to nitrite) are bypassed.
Biological Denitrification of Hydrolysates from Octahydro‐1,3,5,7 tetranitro‐1,3,5,7‐tetrazocine
Authors: Ogden Kimberly L. , Gadgill Jaideep , Akin Tulin
Published: September 2006

Alternatives for the destruction of common military explosives, including trinitrotoluene; hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine; and octahydro‐1,3,5,7 tetranitro‐1,3,5,7‐tetrazocine (HMX) are being investigated in the post‐cold war period. One alternative combines chemical treatment (i.e., base hydrolysis of the explosives) and biological treatment (i.e., denitrification of the hydrolysate). This paper focuses on results of the biological part of the treatment process, during which Hyphomicrobium sp. bacteria were isolated from a seed obtained from a denitrification facility. The bacteria were enriched and maintained on a surrogate waste with methanol as the carbon source. The resulting culture is capable of anoxic growth in waste solutions containing up to 5000 mg/L of nitrite‐nitrogen. The culture efficiently denitrifies both surrogate and actual hydrolysate wastes. A substrate inhibition model was used to accurately predict denitrification rates. Comparisons are made between denitrification rates obtained for surrogate versus actual wastes. Denitrification rates were higher when actual waste streams were used. This work demonstrates the feasibility of using Hyphomicrobium sp. bacteria to treat HMX hydrolysate and presents a model that can be used to design a large‐scale system.
Factors Affecting Photosynthetic Rates of Periphyton in Shallow Streams of Southeastern Pennsylvania
Authors: Davis John F.
Published: September 2006

Photosynthetic rates during low‐flow summer conditions were examined for eight reaches of the Christina Watershed in southeastern Pennsylvania with respect to light and nutrient availability. Photosynthetic rates in these shallow streams ranged from 0.9 to 25.4 g O2/m2·d. Soluble orthophosphorus concentrations ranged from 0.004 to 0.63 mg/L, and phosphorus was considered the limiting nutrient for periphyton growth based on a nitrogen/phosphorus ratio exceeding 10 (by weight). Light availability varied among reaches from densely wooded canopies to open pasture. Nutrient availability was examined in terms of concentration and advective flux, which was calculated as the product of stream velocity and nutrient concentration. Cluster analyses were applied to group the nutrient and light availability factors and the photosynthetic rate responses into low, moderate, and high levels. The most consistent predictor of high photosynthetic rates was the joint occurrence of moderate‐to‐high levels of light and nutrient flux.
The Role of Molecular Methods in Evaluating Biological Treatment Processes
Authors: Rittmann Bruce E.
Published: September 2006

Methods derived from molecular biology provide powerful new tools to analyze biological treatment processes. Because molecular methods can be used to directly interrogate genetic information about the microbial community, they can provide the fine detail that is impossible with the blunt, nondiscriminating information usually obtained from more traditional measures such as biochemical oxygen demand and volatile suspended solids. Molecular methods allow tracking of critical groups of microorganisms, such as ammonia oxidizers, that comprise a small fraction of the total biomass. Molecular methods also allow tracking of specific metabolic reactions or other functions that are key to the satisfactory performance of a system. Despite their power, molecular methods do not provide sufficient information when used alone. Aggregated measures and quantitative modeling remain necessary to establish mass balances, quantify the function of the microbial community, and connect the results of molecular assays to practice. Several examples involving nitrifying bacteria in activated sludge illustrate the fine detail available with molecular methods and how they can be linked to traditional and quantitative analyses. Other manuscripts in this special issue also provide examples of the value of using molecular tools in combination with traditional methods.
Microbial Community Structures in Foaming and Nonfoaming Full‐Scale Wastewater Treatment Plants
Authors: de los Reyes Francis L. , Rothauszky Dagmar , Raskin Lutgarde
Published: September 2006

A survey of full‐scale activated‐sludge plants in Illinois revealed that filamentous foaming is a widespread problem in the state, and that the causes and consequences of foaming control strategies are not fully understood. To link microbial community structure to foam occurrence, microbial populations in eight foaming and nine nonfoaming full‐scale activated‐sludge systems were quantified using oligonucleotide hybridization probes targeting the ribosomal RNA (rRNA) of the mycolata; Gordonia spp.; Gordonia amarae; “Candidatus Microthrix parvicella”; the α‐, β‐, and γ‐subclasses of the Proteobacteria, and members of the Cytophaga‐Flavobacteria. Parallel measurements of microbial population abundance using hybridization of extracted RNA and fluorescence in situ hybridization (FISH) showed that the levels of mycolata, particularly Gordonia spp., were higher in most foaming systems compared with nonfoaming systems. Fluorescence in situ hybridization and microscopy suggested the involvement of “Candidatus Microthrix parvicella” and Skermania piniformis in foam formation in other plants. Finally, high numbers of “Candidatus Microthrix parvicella” were detected by FISH in foam and mixed liquor samples of one plant, whereas the corresponding levels of rRNA were low. This finding implies that inactive “Candidatus Microthrix parvicella” cells (i.e., cells with low rRNA levels) can cause foaming.
Microbial Community Structure and Activity in a Compartmentalized, Anaerobic Bioreactor
Authors: Angenent Largus T. , Zheng Dandan , Sung Shihwu , Raskin Lutgarde
Published: September 2006

The objective of this study was to evaluate staging and its effects on reactor performance in a compartmentalized bioreactor, designated the anaerobic migrating blanket reactor (AMBR). The AMBR was operated by reversing the flow several times per day, which allowed for substantial biomass migration without biomass accumulation in the final compartment. During reactor startup, the structures of the microbial communities in the five compartments were quite similar despite substantial differences in substrate types and concentrations in the different compartments. During the rest of the operational period, biomass migration was reduced by changing operating conditions and, as a result, a larger difference in the structures of the microbial communities developed for the different compartments (biomass staging). For example, after changing operating conditions, rRNA levels for the acetate‐utilizing methanogen Methanosaeta concilii were approximately 35 and 10% of the total rRNA in the middle and outside compartments, respectively (before changing operating conditions these levels were approximately 20 and 12% of the total rRNA, respectively). Promoting larger differences in the structures of the microbial communities for the different compartments did not improve reactor performance as lower levels of M. concilii in the outside compartments hindered acetate removal and compromised effluent quality.