bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical Model for the Interpretation of BMD Scans in Patients Stopping Strontium Ranelate Treatment
Authors: Blake Glen M , Fogelman Ignac
Published: August 2006

Strontium ranelate is a new treatment for osteoporosis that results in large increases in BMD, much of which is an artefact caused by high bone strontium content. We used clinical trial data and a model of long-term strontium kinetics to estimate the effect of past strontium treatment on future BMD measurements.

Introduction: The oral administration of strontium ranelate causes a clinically significant overestimation of BMD because of the high attenuation of X-rays by strontium atoms in bone. As more patients are treated with strontium ranelate, questions will arise about the correct interpretation of their future BMD measurements. We performed a theoretical study to calculate the long-term effect of strontium treatment on BMD and establish the duration of past treatment for which the remaining bone strontium content (BSC) has a negligible effect on BMD.

Materials and Methods: The BMD changes measured at the spine and hip during strontium ranelate treatment were interpolated from clinical trial data. The long-term retention of strontium in bone was estimated using the International Commission on Radiological Protection (ICRP) strontium retention function modified for use in postmenopausal women. Estimates of the strontium BMD artefact after treatment has stopped were performed on the assumption that the BSC effect accounts for 75% of the total measured BMD change at 3 years.

Results: If 75% of the BMD changes are explained by BSC, in the average patient, 3-year treatment leads to a spine BMD artefact of 11.2%, decreasing to 3.8% 10 years after stopping treatment. The BMD artefacts at the total hip and femoral neck sites are smaller by factors of 0.65 and 0.53, respectively. If pre- and post-therapy BMD measurements are available, these predictions can be tailored to the individual patient. On average, 6-month treatment is required for the spine BMD artefact to exceed 3%, the figure adopted as the maximum BMD change caused by bone strontium that has a negligible effect on scan interpretation. Ten years after stopping treatment, 28 months of treatment are required for the residual BMD artefact to still exceed the 3% threshold.

Conclusions: Strontium ranelate treatment lasting for >6 months can affect BMD measurements for many years afterward.
Elevated Skeletal Osteopontin Levels Contribute to the Hypophosphatasia Phenotype in Akp2−/− Mice
Authors: Harmey Dympna , Johnson Kristen A , Zelken Jonathan , Camacho Nancy P , Hoylaerts Marc F , Noda Masaki , Terkeltaub Robert , Millán José Luis
Published: August 2006

Increased levels of ePPi in mice deficient in TNALP (i.e., Akp2−/−) lead to elevated OPN concentrations. We examined the skeletal phenotype of mice lacking both OPN and TNALP and concluded that the increased OPN levels contribute to the hypophosphatasia phenotype characteristic of Akp2−/− mice. We also found that extracellular OPN regulates the PPi output by osteoblasts.

Introduction: Akp2 −/− display mineralization deficiencies characterized by rickets/osteomalacia. This defect has been attributed to the increased levels of extracellular inorganic pyrophosphate (ePPi), a substrate of tissue-nonspecific alkaline phosphatase (TNALP) and a potent inhibitor of mineral deposition. Because elevated levels of ePPi induce Opn gene expression, the Akp2−/− mice also display increased levels of osteopontin (OPN), another inhibitor of mineralization.

Materials and Methods: Akp2 −/− mice were bred into the Opn−/− line. The resulting double knockout mice were analyzed for skeletal abnormalities by histology and μCT. Calvarial osteoblasts were assayed for their ability to mineralize in vitro and were probed for changes in gene expression.

Results: Mice lacking both Akp2 and Opn showed partial normalization at the histological level with regard to mineral deposition and BMD. However, high ePPi levels remained in Akp2−/− mice. We found that Opn−/− mice have themselves elevated levels of ePPi attributable to an increase in Enpp1 and Ank expression and a concomitant downregulation of Akp2 expression in Opn−/− osteoblasts, but that Opn−/− mice have more mineralized osteoid than wildtype (WT) controls despite their elevated ePPi levels. Addition of exogenous OPN to Opn−/− osteoblasts results in downregulation of Enpp1 and Ank gene expression and a reduction of the PPi output by these cells.

Conclusions: Deletion of both Akp2 and Opn can partially rescue the hypomineralized phenotype of Akp2−/− mice. However, these double knockout mice do not display corrected ePPi levels, and we conclude that regulation of hydroxyapatite deposition requires the coordinated actions of both PPi and OPN and that the hypophosphatasia phenotype in Akp2−/− mice results from the combined inhibitory action of increased levels of both ePPi and OPN. Our data also suggest that the ePPi-mediated regulation of OPN and the OPN-mediated regulation of ePPi are linked counterregulatory mechanisms that control the concentrations of these two important mineralization inhibitors, OPN and ePPi.
Sustainable regeneration of former Mackies site, Belfast
Authors: Dunlop J.
Published: August 2006

Waste minimisation, recycling and environmental protection are becoming increasingly important in today's construction industry. Facilities for waste disposal have limited capacity and the availability of natural resources is depleting. This paper considers the sustainable redevelopment of a brown field industrial site and identifies significant cost savings to the client during design development and construction. Techniques adopted during the construction phase of the scheme included the on-site crushing of existing concrete structures for reuse and the bioremediation of oil-contaminated soils in windrows. Soils containing heavy metals were contained on site and groundwater contaminated with solvents was treated on site. The treatment and reuse of materials on site proved very successful and also reduced the requirement for waste disposal to landfill. The wildlife environment of the area was maintained and enhanced with the retention of a main badger sett within the site boundary, the creation of landscaped areas and control of Japanese knotweed. The project is being assessed for a CEEQUAL (Civil Engineering Environmental Quality) Whole Project Award.
Optimum design of sustainable concrete pavements
Authors: Hughes B. P.
Published: August 2006

Optimum design of continuously reinforced concrete pavement (CRCP) can produce low-maintenance sustainable pavements with extremely long service lives. The advantages for roads and highways include low whole-life cost, economic and social benefits from reduced fuel consumption and pollution, reduced man-hour wastage, user frustration and aggravation. Unfortunately, the full potential of CRCP is not realised with conventional pavement design. Furthermore, very few successful structurally enhancing bonded concrete overlays (BCOs) at even lower whole-life cost have actually been achieved. This paper focuses on the essential requirements for a long-life sustainable pavement and outlines the essential shortcomings and deficiencies in conventional CRCP design. Optimum design can only be achieved if both a semi-rigid pavement model and a rigid pavement model are considered jointly. Furthermore, the abysmal failures of many BCOs can also be explained and rectified utilising various concepts outlined in this paper. Optimum combinations of fibre and bar reinforcement are also considered for even further advances in the future when more experimental data, especially field data, become available.
Coagulation of Alkalinized Municipal Wastewater Using Seawater Bittern
Authors: Ayoub G.M. , Merehbi F. , Abdallah R. , Acra A. , El Fadel M.
Published: August 2006

Laboratory studies were conducted to determine the efficacy of seawater bittern as a coagulant for the treatment of municipal wastewater. Freshly collected grab samples of municipal wastewater from two different discharge points were alkalinized to pH levels of 11.4 ± 0.1 by adding slaked lime or caustic soda. Serial dosages of liquid bittern were added and the jar test technique was used to determine the effect of the process on a number of determinant parameters. Seawater, liquid bittern, and dried bittern were used as coagulating agents in one of the four test sets to determine the effect of the three magnesium ion (Mg2+) sources on effluent characteristics. The extent of bacterial inactivation and the use of CO2 to control effluent pH were investigated as well. Seawater liquid bittern was found to be an effective and economic source of Mg2+ that may be used in the treatment of municipal wastewater. Turbidity and suspended solids removal exceeded 95%. Recorded chemical oxygen demand removals were in excess of 75%, while dissolved organic carbon removals averaged approximately 30%. Very limited differences in efficiency of treatment were noted between the use of slaked lime and caustic soda as alkalinizing agents. Besides its reduced bulk when compared to seawater, liquid bittern demonstrated an added advantage (over seawater and dry bittern) in imparting the least increase in dissolved solids to treated effluent. The process is very effective in inactivating fecal bacteria. Carbonation by the addition of CO2 in concentrations ranging between 56 and 362 mL/L (depending on initial levels of pH, alkalinity, and the nature of the alkalinizing agent used) were needed to neutralize clarified supernatants to acceptable levels.
Sludge Blanket Response to Storm Surge in an Activated‐Sludge Clarifier
Authors: Manning William T. , Garrett M. Truett , Malina Joseph F.
Published: August 2006

Aspects of operation and design for storm flows at a 190‐m3/h (1.2‐mgd) dry weather design flow activated‐sludge plant were tested. A significant plant enlargement allowed recycle of test clarifier effluent to the main plant versus discharge to a stream. Thus it was possible to test high overflow rates without risk of a permit violation. On‐line monitoring showed that the return sludge concentration increase lagged approximately 1 hour behind the start of the storm flow. This required an adjustment of the power equation model used. Furthermore, when the overflow rate exceeded the settling velocity of the feed solids, the sludge blanket rose faster than the model prediction. This phenomenon required developing a new model to predict blanket behavior under various loading conditions. The new model allows for plant design to more accurately include a clarifier zone for storing solids during peak flows associated with rain storms. An exponential equation, fitted to settling data, was also used in the new model with test data for comparison. The exponential equation gave a low blanket prediction. Results are compared with those of other research for solids storage during peak flow.
Oxime Inhibition of Nitrification During Treatment of an Ammonia‐Containing Industrial Wastewater
Authors: Love Nancy G. , Smith Roberta J. , Gilmore Kevin R. , Randall Clifford W.
Published: August 2006

Studies were conducted to investigate the nitrification potential of an industrial wastewater that contained high amounts of ammonium sulfate. Laboratory‐scale, activated‐sludge reactors were unable to nitrify the wastewater, but the same sludge began to nitrify within 2 weeks after the feed was changed to a synthetic wastewater. Further investigation indicated that oxime compounds in the industry's wastewater were causing nitrification inhibition. Four oximes known to exist in the industrial wastewater were studied: cyclohexanone oxime was not inhibitory up to 100 mg/L, acetaldehyde oxime and aldecarb oxime were moderately inhibitory, and methylethyl ketoxime (MEKO) was strongly inhibitory to nitrification. The mechanism of MEKO inhibition was evaluated using three different analytical approaches. Methylethyl ketoxime demonstrated pure noncompetitive inhibition patterns using all methods of data analysis. The inhibition constant Ki indicates the concentration that causes 50% inhibition and was estimated to range from 0.3 to 1.9 mg/L at 25 °C for MEKO.
Comparison of Parameters Characterizing Organic Matter in a Combined Sewer During Rainfall Events and Dry Weather
Authors: Servais Pierre , Seidl Martin , Mouchel Jean‐Marie
Published: August 2006

To understand the effect of combined sewer overflows on the river Seine (France), a characterization of effluent in terms of organic matter and bacterial biomass was carried out during several sampling campaigns performed in a combined sewer located in Parisian suburbs under wet and dry weather conditions. Measurements classically used to study wastewater (suspended matter, chemical oxygen demand [COD] and biochemical oxygen demand [BOD]) were compared with the estimate of biodegradable and refractory fractions of particulate and dissolved organic carbon. Relationships among different parameters used to describe organic material in effluent were established. Even for large fluctuations in organic matter concentrations, highly homogeneous ratios between the different descriptors during wet and dry weather were observed, and no significant differences could be observed in two catchments strongly differing by their sizes. The only two small differences in relative composition that could be observed between dry and wet weather were slightly lower content of organic carbon in suspended solids and a lower biodegradability of this material during rain events. Accordingly, with the help of obtained relationships and values of classical variables like turbidity, BOD, and COD for a given effluent, it is possible to make reasonably accurate estimates of its composition in terms of biodegradable and refractory fractions of dissolved and particulate organic matter and bacterial biomass.
Particle Size Distribution and Hydrodynamic Characteristics of Solid Matter Carried by Runoff from Motorways
Authors: Andral M.C. , Roger S. , Montréjaud‐Vignoles M. , Herremans L.
Published: August 2006

This paper studies solid matter from a section of the A9 motorway, Kérault Region, France, used in a study of the effects of pollution. This study analyzed both settled sediments from collecting basin and characteristics of sediments in the water column during and after eight storm events between October 12, 1993, and February 6, 1994. Settled sediments were used to measure particle sizes, mineral content, and related characteristics, whereas water samples were used to document total suspended solids, mineral content, and heavy metals. Solid particles larger than 100 μm in diameter are easily separated by simple settling, unlike particles smaller than 100 μm in diameter, which remain in suspension in runoff. To treat runoff, particles smaller than 50 μm in diameter, which represent approximately three‐quarters of the weight of the solids, must be studied. On average, 50% v/v of particles have a diameter less than 15.2 μm, whereas the geometric mean is 12.6 μm. Regarding sedimentation speed, from the eight rainfalls studied, 50% w/w of particles smaller than 50 μm in diameter fall at a speed less than 2.98 m/h on average (results for the eight rainfalls vary from 2.5 to 3.3 m/h), and 50% of particles between 50 and 100 μm in diameter fall at a speed less than 9.8 m/h on average (results of the eight rainfalls vary from 5.7 to 13.1 m/h). Thus, treatment of runoff entails separating or eliminating solid waste. Furthermore, measuring sedimentation speed of particles with diameters smaller than 100 μm seems to be an essential stage in the design of treatment plants (Vignoles, 1991).
Development of Simulation Model for a Combined Activated‐Sludge and Biofilm Process to Remove Nitrogen and Phosphorus
Authors: Suzuki Yutaka , Takahashi Masahiro , Haesslein Markus , Seyfried Carl F.
Published: August 2006

A simulation model was developed for a combined activated‐sludge and biofilm process that was developed in Japan to achieve nitrogen and phosphorus removal without extending existing treatment facilities. The process consists of an activated‐sludge process of three zones (anaerobic, anoxic, and aerobic) and a biofilm process in the form of fluidized media in the aerobic zone. In this process, nitrification is carried out by nitrifiers on the fluidized media and denitrification and phosphorus removal are performed by activated sludge. First, a biofilm model was developed by modifying components, biological processes, and detachment mechanism of an existing model using experimental results from the fluidized‐bed process. Second, the biofilm model was incorporated in the International Association on Water Quality Activated Sludge Model No. 2 with the addition of a mechanism of transferring detached biofilm to activated sludge. Parameter values of this model were fitted using data from a pilot plant during a period of no rainfall. The model was then evaluated with pilot‐plant data for a period of rainfall. The model developed for the combined activated‐sludge and biofilm process described water quality of the pilot plant well. Necessary improvements are also discussed.
The Effect of Temperature on Biochemical Oxygen Demand Removal in a Subsurface Flow Wetland
Authors: Griffin D.M. , Bhattarai Rishi Raj , Xiang Hongjian
Published: August 2006

Investigators have reported that seasonal variation in wastewater temperature has little or no effect on biochemical oxygen demand (BOD) removal in subsurface flow wetlands (also referred to as rock–plant filters). This study examined temperature and BOD data collected biweekly (every 2 weeks) over an 18‐month period from a rock–plant filter treating high‐strength wastewater (median pump station discharge BOD = 425 mg/L) at an interstate highway rest area in south central Louisiana. Results show a seasonal variation in effluent BOD with greater mean removal occurring when wastewater temperature in the splitter box is greater than 20 °C, whereas removal at wastewater temperature less than 20 °C exhibits a wider variation and lower mean. An exponential model relating splitter box temperature to effluent BOD concentration, R2 = 0.69, fits the data only slightly better than an Arrhenius type relationship, R2 = 0.67. Both models suggest that two cells in series may be required for this facility to meet its BOD permit limit in colder weather. A linear model relating percent of BOD removed to splitter box temperature did not fit data as well (R2 = 0.50).
Laboratory Studies of Aqueous Partitioning Tracer Tests for Measuring Nonaqueous Phase Liquid Volumes
Authors: Gierke John S. , Sanders Deborah L. , Perram David L.
Published: August 2006

The partitioning tracer test (PTT) is an innovative method for measuring nonaqueous phase liquid (NAPL) volume distributions in contaminated aquifers. During a PTT, a tracer pulse containing nonpartitioning and partitioning tracers is injected to an aquifer and extracted from downgradient wells. The appearance of the tracers at downgradient locations is analyzed to determine tracer mean residence times, for example, using the methods of moments and retardation factors based on residence times. The NAPL volume present in the tracer flow path is then determined based on retardation factors and independently measured tracer partition coefficients. Column experiments were performed to assess the validity of PTTs conducted at a former chemical disposal pit at Hill Air Force Base, Utah. The NAPL contamination was a complex mixture of volatile and semivolatile organic chemicals. Up to four alcohol tracers were used in PTTs: methanol; n‐hexanol; 2,2‐dimethyl‐3‐pentanol; and 6‐methyl‐2‐heptanol and batch test, conducted at 10 °C yielded partition coefficients of 0, 2.07, 7.42, and 18.8, respectively. Partition coefficients increased between 53 and 60% with a 12 °C increase in temperature. Column experiments were used to evaluate the validity of using a PTT for field test conditions of temperature and average flow velocity. Measured NAPL volumes based on comparing three replicate column tests using two to three partitioning tracers and different flow rates were within 84.3 to 101% of the NAPL volume used to contaminate the column (overall, 8.91% of the pore volume contained NAPL). The average NAPL saturations from all the tracers yielded estimates between 89 to 99% of the known value. Afterwards, the column was sparged with 5800 pore volumes of air, and the subsequent PTT yielded an estimate of the reduction in NAPL volume of 16%.
Research Needs in Urban Wet Weather Flows
Authors: Heaney James P. , Wright Leonard , Sample David
Published: August 2006

The results of a national assessment of research needs in urban wet weather flow management are presented. Three interrelated categories of urban wet weather flow management are discussed: combined sewer overflows, sanitary sewer overflows, and urban stormwater discharges. The initial compilation of wet weather flow research needs totaled 154 research projects, which was later reduced to 69 higher‐priority research projects for which detailed literature reviews were compiled. From this group, 26 topics were selected as priority research topics. Within this paper, the results of the assessment were organized into the following ten categories:(1) sources and monitoring; (2) receiving water effects; (3) other effects; (4) management; (5) models and decision support systems; (6) watershed management linkages; (7) regulatory policies and financial aspects; (8) source controls; (9) collection system controls; and (10) storage/treatment systems. A summary of the authors' views on research needs within each category is provided. An expenditure of an estimated $20 to $40 million per year in the U.S. is needed to address the identified research needs.
Tertiary Treatment Using Microfiltration and UV Disinfection for Water Reclamation
Authors: Jolis Domènec , Hirano Robin , Pitt Paul
Published: August 2006

Microfiltration and UV disinfection are two alternative technologies for water reclamation. The results of a pilot study combining these two processes are presented. In addition to producing filtrate turbidities averaging 0.06 nephelometric turbidity units, microfiltration was an effective barrier to pathogens, demonstrating average log reductions of 4.5 for total coliforms and 2.9 for MS2 bacteriophage. Ultraviolet disinfection following microfiltration reliably met the California Wastewater Reclamation Criteria (Title 22) total coliform standard of 2.2 colony‐forming units/l00 mL at a UV dose of 450 J/m2. The MS2 bacteriophage standard, which requires a 5‐log reduction, was achieved by microfiltration and a UV dose of 880 J/m2. A model of the kinetics of inactivation of MS2 bacteriophage was used in further analysis of disinfection data. The model indicated that considerable backmixing occurred in the pilot UV disinfection unit, and observed UV doses could be reduced with improved hydraulics.
Stimulation of Sulfate‐Reducing Bacteria in Lake Water from a Former Open‐Pit Mine Through Addition of Organic Wastes
Authors: Castro James M. , Wielinga Bruce W. , Gannon James E. , Moore Johnnie N.
Published: August 2006

A method to improve water quality in a lake occupying a former open‐pit mine was evaluated in a laboratory‐scale study. Untreated pit lake water contained high levels of sulfate, iron, and arsenic (1 200, 100, and 5 mg/L, respectively) and was mildly acidic (∼pH 6). Varying amounts of two locally available organic waste products (waste from a potato‐processing plant and composted steer manure) were added to pit water and maintained in microcosms under anoxic conditions. In selected microcosms, populations of sulfate‐reducing bacteria increased with time; sulfide was generated by sulfate reduction; sulfate, iron, and arsenic concentrations approached zero; and pH approached neutrality. Best results were obtained with intermediate amounts of waste potato skin.
Factors Affecting Floc Properties During Aerobic Digestion: Implications for Dewatering
Authors: Murthy Sudhir N. , Novak John T.
Published: August 2006

Laboratory aerobic digestion studies were conducted to determine the effect of divalent cations on the characteristics of aerobically digested activated sludge. Separate reactors were operated at two divalent cation concentrations. Characteristics examined included dewatering properties (cake solids, specific resistance to filtration, and capillary suction time), polymer conditioning requirement, floc strength, supernatant chemical oxygen demand (COD), supernatant turbidity, soluble cations (sodium, potassium, calcium, magnesium, and ammonium ions), soluble anions (nitrate and nitrite), and soluble exocellular polymers (proteins and polysaccharides). The reactor containing higher amounts of calcium and magnesium (1.25 mM each) exhibited better dewatering properties, higher floc strength, lower polymer conditioning requirement, lower soluble COD, lower supernatant turbidity, and lower soluble exocellular polymers than the reactor containing lower calcium and magnesium concentrations (0.40 mM each). Floc deterioration was associated with a release of soluble proteins and polysaccharides and monovalent cations (sodium and potassium) to the bulk solution. Divalent cations were not released to the bulk solution, indicating they may participate in floc binding. Mineralization of nitrogen was not affected, suggesting that aerobic digestion of activated‐sludge solids (degradation rates) was not affected. These results imply that the addition of divalent cations improves aerobic digester performance with regard to floc properties, supernatant quality (implications for recycled COD), and dewatering performance.
A Comparison of Physical Properties of Synthetic Sludge with Activated Sludge
Authors: Sanin F. Dilek , Vesilind P. Aarne
Published: August 2006

Conducting physical and chemical tests with activated sludge is difficult because of its constantly changing properties. To overcome this difficulty a synthetic sludge that physically and chemically resembles activated sludge was created. In this study, the physical properties of synthetic sludge were examined and compared to those of activated sludge, including particle size, filterability by specific resistance to filtration and capillary suction time, conditioning with two polyelectrolytes, floc strength, rheological properties, and residual turbidity after settling. Results of this study show striking similarities between activated sludge and synthetic sludge. Filterabilities of both sludges are almost identical. A medium‐molecular‐weight, medium‐charge‐density, cationic polymer is effective in conditioning both sludges at approximately the same dose. Activated sludge is found to have stronger flocs than synthetic sludge. However, both sludges seem to have flocs stronger than some loose and weak flocs reported in the literature. Rheological behavior in terms of apparent viscosity of the two sludges is similar. The average particle size of activated sludge is found to be slightly larger than that of synthetic sludge. Also, synthetic sludge has a higher residual turbidity than activated sludge. These differences are explained by the fact that the synthetic sludge is lacking filamentous microorganisms that form the backbone of a floc structure in activated sludge. Even though there are some differences in properties, because its overall behavior is close to that of activated sludge, synthetic sludge can be used as a surrogate material for activated sludge when reproducibility in testing is necessary.
Preventing Growth of Pathogens in Pasteurized Digester Solids
Authors: Ward Amanda , Stensel H. David , Ferguson John F. , Ma Gregory , Hummel Stan
Published: August 2006

The goal of this research was to determine conditions that could promote or inhibit pathogen growth during storage or application of pasteurized digester solids. Growth of enterobacteriaceae and Salmonella after pasteurization (70 °C for 30 minutes) of mesophilic anaerobic digester solids was reported for numerous facilities in Switzerland but the cause was not known. However, our work found no growth of indigenous Salmonella or fecal coliform in well‐mixed pasteurized samples in bench‐scale conditions. Salmonella typhimurium was then added in batch tests to determine growth or die‐off at 20 and 35 °C incubation temperatures. In addition, pasteurized digester solids were fed for 3 months to a laboratory 6‐day solids retention time (SRT) secondary mesophilic digester to determine if pathogen growth could occur. Fecal coliform die‐off occurred in inoculated pasteurized solids under all conditions, but Salmonella growth readily occurred within 5 days and died off within 30 days of incubation. The Salmonella grew better at 20 than at 35 °C, and substrate addition did not improve growth. When the pasteurized solids were mixed and oxygenated, Salmonella die‐off instead of growth occurred. Experiments at 35 °C with both batch bottles and the secondary digester showed that the presence of other active anaerobic bacteria apparently caused Salmonella die‐off instead of growth. Pathogen growth can be prevented and Class A biosolids can be ensured by storing pasteurized digester solids in a secondary mesophilic digester with a 6‐day SRT.
Removal of Selenite and Chromate Using Iron(III)‐Doped Alginate Gels
Authors: Min Joon H. , Hering Janet G.
Published: August 2006

Oxyanionic contaminants, specifically selenium and chromium(VI), were removed from solution by sorption onto gel beads formed by pretreating the biopolymer alginic acid with calcium and iron(III). The calcium‐iron gel beads were found to be effective at removing selenium(IV) from solution. Chromium(VI) removal was less effective and the rate of sorption was slower than that of selenium(IV). At an initial selenium(IV) concentration of 400 μg/L (5.1 μM), up to approximately 94% removal of selenium from solution was achieved by a 120‐hour equilibration with 20 calcium‐iron beads (10 mg/L or 180 μM total iron). Optimal selenium(IV) removal and stability of the calcium‐iron beads were achieved at pH 4. Selenium(IV) sorption and kinetics data were comparable with those observed previously for arsenic(V). Selenium(IV) sorption data, as a function of dissolved concentration and iron content, were modeled. As calcium‐iron beads became saturated, the extent of sorption of selenium(IV) or arsenic(V) was decreased by the presence of competing contaminant oxyanions or nonhazardous inorganic anions such as phosphate.
Chemical inhibitors for biosolids pellets to promote stability during transport and storage
Authors: Long Sharon C. , Seavey Douglas L. , Switzenbaum Michael S. , Bailey Nathaniel O.
Published: August 2006

The Massachusetts Water Resources Authority (MWRA) serves the metropolitan Boston area and has been heat‐drying and pelletizing its biosolids for beneficial reuse since 1991. Episodes of self‐heating, associated with rewetting of the pellets in rail cars that are not rain‐tight, have been observed periodically during rail car shipments when the pellets arrive at their destination smoldering. Biological activity may play an important role in these self‐heating incidents because rewetted pellets contain significant amounts of readily utilized organic material. This study identified the critical moisture level at which microbial activity is significantly initiated and examined several additives that would delay the onset of biological activity during transport. Through the use of respirometric techniques, microbial activity was measured. Propionic acid, citric acid, and sodium sulfite, food additives that can significantly inhibit microbial growth without presenting human health or ecological risks at the typical levels used in foods, and Dustrol 3010 (Arr‐Maz Products, Inc., Winter Haven, Florida), a dust‐control agent currently being used by MWRA, were investigated. The critical pellet moisture content that induces measurable oxygen uptake is 9% by weight. All four additives delayed the onset of microbial oxygen uptake, and dosages ranging from 20 to 88 mg additive/g pellets reduced oxygen uptake rates by 80 to 90% for a period of 5 to 7 days.
Comparison of methods for determining biodegradation kinetics of volatile organic compounds
Authors: Rajagopalan S. , van Compernolle R. , Meyer C.L. , Cano M.L. , Sun P.T.
Published: August 2006

Regulations, such as the Synthetic Organic Manufacturing Industry Hazardous Organic National Emission Standards for Hazardous Air Pollutants (SOCMI‐HON) rule of the recently promulgated Clean Air Act Amendments, target the reduction of emissions of volatile organic compounds (VOCs) from industrial sources including process vents, tanks, equipment leaks, and wastewater. As required by the regulation, Method 304 was used to measure the VOC biodegradation kinetics, which were then used to determine the degree of biodegradation versus air stripping. In addition to Method 304, batch tests that use oxygen addition (BOX tests) and serum bottle (SB) tests were use dto determine the biodegradation kinetics of ethylene oxide (EO) andacetaldehyde (AA) in a chemical plant. The Method 304 first‐order rate constant was measured to be 0.99 L/g · h and 0.24 L/g · h for EO and AA, respectively. Linearized first‐order rate constants from the BOX and SB tests were greater than the Method 304 rate constants by at least an order of magnitude. Also, the BOX tests and SB test kinetics correctly predicted full‐scale bioreactor emissions, whereas the Method 304 kinetics did not.
An empirical model for predicting the organic concentration of anaerobic filter effluents
Authors: Wilson Francis , Yu Hanqing , Tay Joo‐Hwa , Gu Guowei
Published: August 2006

The results of experiments in treating domestic wastewater and soybean processing waste‐water in two laboratory‐scale anaerobic filters are described. An empirical model, with inlet chemical oxygen demand (COD) concentration Si and hydraulic retention time (HRT) as two independent variables to predict the outlet COD concentration of the anaerobic filters, was found to adequately describe the anaerobic filter systems. Good agreement was obtained between the prediction using the current model and the experimental results of pilot‐ and full‐scale anaerobic filters for the treatment of soybean processing wastewater. The current model, which is able to show the predominant parameter (Si or HRT) determining the outlet organic concentration, is a modification of Young and McCarty's (1969) model. The current model also implies the possible effect of effluent recirculation on the performance of an anaerobic filter.
Use of a hydrogen‐diffusion electrode in the electrochemical removal of lead from effluents of lead electrowinning processes
Authors: Expósito E. , Sáez A.
Published: August 2006

An electrochemical process for the removal of lead using a three‐dimensional carbon‐felt cathode and a hydrogen‐diffusion anode has been developed. The process is able to cope with effluents coming from lead electrowinning processes in fluoroborate baths after the lead has been electrolytically removed to approximately 100 mg/L (100 ppm). The lead deposit can be removed from carbon‐felt electrodes by chemical or electrochemical stripping, yielding a lead‐containing solution that can be reused in the electrowinning process. The use of a hydrogen‐diffusion electrode (HDE) significantly decreases the cost of the process in comparison with that of a dimensionally stable anode (DSA). For a current density of 10 mA/cm2, the energy used for treating a solution containing 120 mg/L (120 ppm) of lead is approximately 990 kJ/m3 (275 W h/m3) when a DSA is used, but only 166 kJ/m3 (46 W h/m3) when an HDE anode is used. Approximately 75% of the hydrogen needed for the HDE anode can be partially supplied by the hydrogen evolved at the cathode during lead deposition. The cathodic reaction has a current efficiency of 25%. The required electrodic area for the removal process is l.5 m2/m3 · h for an effluent containing 120 mg/L (120 ppm) of lead.
Dissolved oxygen control and simultaneous estimation of oxygen uptake rate in activated‐sludge plants
Authors: Suescun Joaquín , Irizar Ion , Ostolaza Xabier , Ayesa Eduardo
Published: August 2006

The theoretical basis, practical implementation, and experimental validation of an on–off control strategy for dissolved oxygen (DO) in aerobic reactors of pilot‐scale activated‐sludge plants with simultaneous estimation of oxygen uptake rate are presented. The effect of dead time and a long response time for robust DO probes has been carefully analyzed and corrected through modeling of the dynamic response of the sensor. Study results indicate that the amplitude of the control band depends on the dead time of the probe. Simultaneous estimation of the volumetric mass‐transfer coefficient for DO (KLa) permits a continuous check of the aeration equipment. Experimental validation has been achieved in a continuous pilot‐scale plant.
Nitrogen removal in a partial nitrification/complete denitrification process
Authors: Potter Thomas G. , Tseng Chie‐Chien , Koopman Ben
Published: August 2006

Using computer modeling and experimentation with a bench‐scale prototype, a novel process for partial nitrification/complete denitrification (PN/CD) to achieve nitrogen removal equivalent to that obtained with the Ludzack‐Ettinger (LE) process is demonstrated. Based on simulation results, the PN/CD process reduces aeration energy costs by up to 16% and energy requirements for recirculation and recycle pumping by up to 28% compared to the LE process. Furthermore, the total reactor volume of the PN/CD process is 26 to 44% less than that required by the LE process for equivalent nitrogen removal. The bench‐scale PN/CD process was operated to confirm the feasibility of the proposed approach. The wastewater feed to this system was settled domestic wastewater supplemented with ammonia and acetate. The experimental PN/CD process met a 12‐mg/L discharge limit on total nitrogen. Relative concentrations of ammonia and nitrate in the effluent were successfully controlled by varying the rate of mixed liquor recirculation. Process performance was not sensitive to dissolved oxygen concentrations of 1 to 3 mg/L in the aerated reactors.
Measurement of ammonium concentration and nitrification rate by a new titrimetric biosensor
Authors: Massone Alessandro , Gernaey Krist , Rozzi Alberto , Verstraete Willy
Published: August 2006

Nitrifiers are more sensitive than heterotrophic bacteria to environmental changes (such as temperature, pH, shock loads as biological oxygen demand or nitrogen, and toxic/inhibiting loads). Moreover, they are slow‐growing bacteria. Thus, a careful control of their activity is needed to achieve continuous good effluent quality. To maintain an actively nitrifying population, efficient process control requires monitoring of the toxicity and the ammonium concentration. The latter is commonly measured by on‐line ammonium analyzers. A new sensor has been developed to measure both the ammonia nitrogen (NH4+‐N) content in the mixed liquor and the activity of the nitrifiers. The operating principle of the biosensor is based on a titration method, which measures the protons produced during nitrification. This paper describes the biosensor and the experimental results (estimation of NH4+‐N concentration and nitrification rate) obtained using activated sludge from wastewater treatment plants receiving hospital and food industry effluents. The influence of changes in operational factors such as pH, temperature, and bicarbonate alkalinity on the measurements has been examined. The potential applications of the system as an on‐line biosensor are outlined.
Enhancing solubilization of sparingly soluble organic compounds by biosurfactants produced by Nocardia erythropolis
Authors: Park Andrew J. , Cha Daniel K. , Holsen Thomas M.
Published: August 2006

The goal of this research was to produce nontoxic, biodegradable surfactants from Nocardia erythropolis (American Type Culture Collection [ATCC] 4277) and to investigate their potential for enhancing the solubility of sparingly soluble organic compounds (SSOCs). After biosurfactants were harvested from the culture broth, SSOC removal capabilities from aqueous systems by micelles and monomers were determined. Nocardia erythropolis was grown in a 500‐mL batch reactor with n‐hexadecane as the sole carbon source. Surface tension of the mineral salts medium dropped from 64 dyne/cm to 41 dyne/cm within 24 hours after inoculation with an acclimated culture of N. erythropolis, indicating the production of appreciable quantities of surface‐active agents. The lowest surface tension value of 35.2 dyne/cm was reached in 4 days. Maximum production of surfactant was also observed at 4 days. Sparingly soluble organic compounds were partitioned into surfactant micelles that form when the surfactant concentration exceeds the critical micelle concentration. Sparingly soluble organic compound partitioning into micelles increased with decreasing SSOC solubility. The partition constants by micelles were 0.002 0, 0.008 6, and 0.041 2 L/mg for toluene, p‐xylene, and trimethylbenzene, respectively. The partitioning capacity of p‐xylene by the biosurfactants produced from N. erythropolis was an order of magnitude greater than that by the synthetic surfactant sodium dodecylsulfate (SDS).
A Rotating Membrane Contactor: Application to Biologically Active Systems
Authors: Johnson Drew W. , Semmens Michael J. , Gulliver John S.
Published: August 2006

Gas transfer through hollow fiber membranes allows for rapid transfer kinetics, high transfer efficiencies, and the ability to precisely control transfer rates. Despite these advantages, membrane gas transfer has not been used extensively in industrial fermentation or wastewater treatment. Module plugging and biofouling are problematic with current contactor designs, making membrane gas transfer unattractive for applications where the growth of microorganisms is encouraged. Recently, a novel rotating contactor configuration was designed to give high transfer rates and simultaneously alleviate these problems. In the rotating contactor configuration, the hollow fiber membranes are pulled through the water, reducing energy requirements. Solids are also able to pass through the fluidized fibers without being filtered. In addition, the entire fiber length experiences a similar flow velocity. This makes the control of biological fouling possible. Pilot plant experiments on a rotating membrane contactor operated in wastewater are presented. The performance of the rotating contactor design in such an environment where the potential for biological fouling exists is evaluated as a function of operating parameters and time in service. Membrane failures are addressed and the transfer performance is compared to other contactor configurations and aeration systems.
Optimal Allocation of Waste Loads in a River with Probabilistic Tributary Flow Under Transverse Mixing
Authors: Li Shiyu , Morioka Tohru
Published: August 2006

A model is proposed for the optimal allocation of waste loads in a river basin, taking into account transverse mixing resulting from the confluence of tributaries with different pollutant levels and the variation of river flow rates. The model is stated as the minimization of cost of wastewater treatment in the whole river basin, subject to the satisfaction of environmental standards imposed for the river quality at water intakes along the river. The flow rate of the river system is regarded as a random variable in the model and constraints on water quality levels are expressed in a probabilistic form. The model is applied to a river with three tributaries joining at one point. The frequency of flow rate of the river system is approximately represented by that of flow rate groups obtained by using statistical methods. Results of the model application show that the priority of wastewater treatment shifts from one tributary subbasin to another when environmental standards are changed, reflecting the effect of transverse mixing in the mainstream. Water quality violations caused by flow rate groups are discussed in the study.
Treatment of Hydrolysates of the High Explosives Hexahydro‐1,3,5,‐Trinitro‐1,3,5‐Trianize and Octahydro‐1,3,5,7‐Tetranitro‐1,3,5,7‐Tetrazocine Using Biological Denitrification
Authors: Zoh Kyung‐Duk , Daniels Jeffrey I. , Knezovich John P. , Stenstrom Michael K.
Published: August 2006

Alkaline hydrolysis byproducts of the high explosives hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) and octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX), consisting of acetate, formate, formaldehyde, and nitrite, were treated in a denitrifying (anoxic) packed‐bed upflow reactor. Additional nitrite or nitrate was added to match the carbon oxidation requirement. In a 2‐year study, more than 90% removal of the organic compounds and nitrite were observed in a reactor with a 3‐hour retention time. Removal was quantified by measuring actual compound concentrations and total organic carbon. The stoichiometry of the experimental results closely matched the predicted stoichiometry. Formaldehyde and acetate were preferentially removed over formate. The system removed N (nitrite):C (acetate):C (formaldehyde):C (formate) in a relative ratio of 1:0.07:0.36:0.50, respectively. The volumetric removal rate was as high as 170 mg/L of nitrite‐nitrogen per day with existing carbon sources. The observed cell yield (mass basis) of nitrite reduction with acetate/formate was 0.21 mg cells/mg total organic carbon or 0.16 mg cells/mg chemical oxygen demand at 20 °C. This culture was also capable of biodegrading RDX and HMX when using nitrate as an electron acceptor.
Effects of Dissolved Organic Matter and pH on Heavy Metal Uptake by Sludge Particulates Exemplified by Copper(II) and Nickel(II): Three‐Variable Model
Authors: Wang Jianmin , Huang C.P. , Allen Herbert E. , Poesponegoro Ira , Poesponegoro Haryanto , Takiyama Luis R.
Published: August 2006

Dissolved organic matter (DOM) and pH are important factors affecting heavy metal uptake by sludge particulates. Copper(II) and Nickel(II) uptake behavior by primary and secondary sludge particulates was studied under various pH and DOM conditions. A three‐variable model, incorporating effects of pH and DOM, was developed to describe heavy metal uptake. Results show that heavy metal uptake by sludge particulates can be better described by the three‐variable model than by the modified Langmuir model in a wide pH range.
Correlations of Aeromonas hydrophila with Indicator Bacteria of Water Quality and Environmental Factors in a Mountain Stream
Authors: Hirotani Hiroshi , Sese Chiaki , Kagawa Hisanori
Published: August 2006

The occurrence of Aeromonas hydrophila in a mountain stream was studied quarterly for more than 3 years. A. hydrophila and fecal coliforms were measured by the membrane filter method, and heterotrophic plate counts (HPC) were measured by the pour plate method at 20 and 35 °C. A. hydrophila was detected from all samples collected and correlated with HPC, especially at 35 °C, but not with fecal coliforms. A. hydrophila densities along the main stream in a log scale correlated positively with the catchment areas in a log scale. The intercepts of the regression lines correlated positively with the mean water temperatures along the channel, which is considered to reflect the growth of the bacterium on the stream bed. The slopes correlated negatively with total precipitation in a 60‐day period before each sampling. These results suggested that the factors controlling A. hydrophila in a mountain stream were water temperature and precipitation, and that the bacterium was indigenous to stream environment rather than from contamination because of human activity.