bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of organically contaminated groundwaters in municipal activated sludge systems
Authors: Smith John R. , Neuhauser Edward F. , Middleton Andrew C. , Cunningham James J. , Weightman Robin L. , Linz David G.
Published: February 2012

ABSTRACT:   A pilot‐scale treatability study was performed to evaluate the capability to effectively co‐treat pumped groundwaters from industrial sites with municipal wastewaters at publicly owned treatment works (POTWs) employing activated sludge treatment. Chemicals given focused attention included selected phenolic, polycyclic aromatic hydrocarbon (PAH), and volatile aromatic compounds. The study involved the simultaneous operation of three pilot‐scale activated sludge reactors. One reactor was fed 100% municipal wastewater (control), a second was fed a 5% by flow volume site groundwater with a relatively low organic concentration, and a third was fed a 20% by flow volume site groundwater with a higher organic concentration. Monitoring was carried out to address, through reactor mass balance computations, chemical fate in terms of activated sludge adsorption, biodegradation, volatilization, and effluent discharge quality. The results of this study support the co‐treatment of contaminated groundwaters in POTWs employing activated sludge systems. The results show nonmeasurable effects in terms of activated sludge treatment performance, and nonsignificant effects in terms of treated effluent discharge and waste activated sludge quality. This work can be used to aid engineers and POTW authorities in evaluating the capability of activated sludge treatment systems to effectively handle and treat groundwaters containing phenolic, PAH, and volatile aromatic compounds.
Removal of toxicity and some nonconventional pollutants by a dual power multicellular lagoon system
Authors: Kantardjieff Alexandra , Jones J. Peter
Published: February 2012

ABSTRACT:   Aerated stabilization basins (ASBs) are a common unit process for treating pulp and paper mill wastewaters in North America but are often unable to meet current requirements. One possible solution is the conversion of the existing system to a dual power level multicellular aerated lagoon. The dual power level lagoon process is a higher rate modified ASB system allowing effluent improvement, energy optimization, and total detention time reduction. To evaluate the suitability of such a system for the treatment of unbleached kraft mill effluent mixed with a municipal wastewater, industrial scale pilot plant tests were conducted over a period of 9 months. The BOD removal kinetics and the ability of the system to reduce effluent toxicity were evaluated for several operating conditions. The dual power level multicellular lagoon process was able to produce effluent nontoxic to rainbow trout, Daphnia magna, and photoluminescent bacteria, despite a median lethal concentration of the untreated effluent in the range of 18 to 24% (96 h LC 50). This effluent also met the requirements for BOD and suspended solids. The treated effluent was analyzed for several nonconventional pollutants (including toluene, styrene, phenolic compounds, and surfactants) and some extractable organic compounds. In general, few contaminants showed concentrations above analytical detection limit levels. Those that did have positive values were generally present in concentrations less than 1 μg/L. The observed concentrations were consistent with a joint U.S. EPA and Ontario Forest Industry Association screening study of pulp and paper mill effluents. The concentrations were close to analytical detection limits.
Selecting among physical/chemical processes for removing synthetic organics from water
Authors: Dvorak Bruce I. , Lawler Desmond F. , Speitel Gerald E. , Jones Darrell L. , Boadway Deborah A.
Published: February 2012

ABSTRACT:  A rational framework for selecting the least‐cost treatment technology for aqueous organic wastes was developed by using performance and cost models. The following three treatment options were evaluated for 15 different chemicals in this research: packed tower air stripping, packed tower air stripping followed by gas‐phase adsorption (granular activated carbon) of off‐gases, and liquid‐phase adsorption (granular activated carbon). The least‐cost air stripping tower design was found to change when off‐gas treatment was added. Air stripping without off‐gas treatment was determined to be less expensive than liquid‐phase adsorption in nearly every case. A methodology was created for comparing the relative costs of liquid‐phase adsorption and air stripping with gas‐phase adsorption. The comparison methodology is based upon physical parameters of the target chemical: Henry's constant and the solute distribution parameter. The result is a diagram for rapid identification of cases for which one treatment option is significantly less expensive than the other.
Use of iron minerals in optimizing the peroxide treatment of contaminated soils
Authors: Watts Richard J. , Udell Matthew D. , Monsen Robert M.
Published: February 2012

ABSTRACT:  The treatment of silica sand contaminated with pentachlorophenol (PCP) using the standard Fenton's reagent procedure, sequential addition of iron (II) and H2O2, and a goethite (α‐FeOOH)‐H2O2 system was investigated. The standard Fenton's procedure oxidized 10 mg/L soluble PCP, but was ineffective in degrading 10 mg/kg or 250 mg/kg particulate and sorbed PCP in silica sand. Sequential addition of excess reagents (480 mg/L iron (II) and 7% H2O2) degraded particulate and sorbed PCP, but with high stoichiometric H2O2 requirements. The most efficient system for PCP degradation was the H2O2‐goethite system. Although the experimental system used in this research lacks the complexity of natural soils, the data suggest that under proper conditions, the iron oxyhydroxide fractions of the soil matrix catalyze Fenton‐like reactions, and that these mineral‐catalyzed reactions may be the most efficient mechanism for the catalyzed hydrogen peroxide treatment of contaminated soils.
Autothermal thermophilic aerobic digestion of municipal sludges: A one‐year, full‐scale demonstration project
Authors: Kelly Harlan G. , Melcer Henryk , Mavinic Donald S.
Published: February 2012

ABSTRACT:  A three‐facility, full‐scale pilot program was undertaken at three small wastewater treatment plants in British Columbia, Canada. The project concludes several years of investigation and one year of plant evaluations for sludge treatment using autothermal thermophilic aerobic digestion (ATAD). Process effectiveness was shown by demonstration of pasteurization, stabilization, and odor acceptability. Control parameters were accessed by use of oxidation reduction potential (ORP), temperature, pH, air flow rates, and energy use. Dewaterability was also studied. The studies concluded that the ATAD process was suitable for use in small communities. The information presented is taken from the final project report and is supplemented with design suggestions for use when considering the ATAD process.
Recovery of macroinvertebrate communities from metal pollution in the South Fork and mainstem of the Coeur d'Alene River, Idaho
Authors: Hoiland Wade K. , Rabe Fred W. , Biggam Russell C.
Published: February 2012

ABSTRACT:  Mining has severely impacted the biota in the Coeur d'Alene River drainage of northern Idaho. The benthic community of the South Fork and mainstem was monitored from 1968 to 1971 and from 1987 to 1991 to determine the effects of improved mine wastewater treatment and mine closures. With the decrease of heavy metal levels, the benthic community showed a gradual recovery as evidenced by large increases in taxonomic richness (0 to 18), Ephemeroptera‐Plecoptera‐Trichoptera index (0 to 8), and species diversity (0 to 1.8). Although considerable recovery has occurred, the biotic integrity of impacted sites continues to lag behind reference sites, probably due to poor habitat structure and metals leaching from mine tailings.
Performance of upflow anaerobic sludge blanket reactor carrying out biological hydrolysis of urea
Authors: Latkar Madhuwanti , Chakrabarti T.
Published: February 2012

ABSTRACT:  Biological hydrolysis of urea was studied in an upflow anaerobic sludge blanket (UASB) reactor. Methanol was used as the source of carbon. Modified diacetyl monoxime method was used for the determination of urea in samples having a high background of ammoniacal nitrogen to hydrolyse 100% urea at loadings of 7.09 kg/m3 bed vol/d and below. The reactor could be operated at 100% efficiency with NH4+‐N loading of 3.43 kg NH4+‐N/m3 bed vol/d. The highest COD utilization rate was 2.32 kg/m3 bed vol/d. The advantages of the UASB reactor over the fixed film‐fixed bed (FFFB) and the continuous flow stirred tank reactor (CFSTR) are discussed in the paper.
Measurement of volatile acid concentration in anaerobic processes by least squares regression of overdetermined titration data
Authors: Bisogni J. J.
Published: February 2012

ABSTRACT:  A numerical procedure is presented which determines the volatile acid content of a sample using standard acid titration data. The procedure uses all available titration data instead of the customary single endpoint titration volume. In many cases volatile acid content can be resolved into acetic and propionic acid components. The procedure is verified using solutions of known concentrations. The procedure gives comparable results to the silicic acid chromatography separation technique.
Bactericidal effect of long chain fatty acids in anaerobic digestion
Authors: Rinzema Arjen , Boone Martin , van Knippenberg Karin , Lettinga Gatze
Published: February 2012

ABSTRACT:  The effect of shock loads of long chain fatty acids (LCFA) on the activity of granular methanogenic sludge was studied with capric acid as model substrate. The results show that inhibition is primarily related to the LCFA concentration; the LCFArbiomass ratio is less important. A lethal threshold LCFA concentration can be distinguished in reactors with identical physical and chemical conditions and inoculum properties: the acetogenic and methanogenic population is killed virtually completely when the concentration exceeds 6.7 to 9.0 mol/m3 capric acid. The observed variation in the threshold level may be attributable to differences in mass transfer rate from liquid to granules in different experiments. At most, 0.2% of the acetotrophic methanogens survives, when the LCFA concentration in a methanogenic digester exceeds the lethal threshold level. Mass balance analysis shows that obligate hydrogen producing acetogenic bacteria and hydrogenotrophic methanogens recover first, followed by acetotrophic methanogens. Recovery of acetotrophic methanogenesis can be described by exponential growth of a small number of survivors. Acetotrophic methanogens do not adapt to LCFA, neither after repeated exposure to toxic concentrations, nor after prolonged exposure to non‐toxic concentrations. A low LCFA (lipid) concentration in the influent promotes faster growth of acetogenic bacteria capable of degrading LCFA.
Disappearance and crop uptake of PCBs from sludge‐amended farmland
Authors: Gan D. Robert , Berthouex P. M.
Published: February 2012

ABSTRACT:  The Madison Metropolitan Sewerage District (MMSD) has conducted a five‐year (1985‐1990) field experiment to obtain data that provide a scientific basis for regulating land disposal of sludge contaminated with polychlorinated biphenyls (PCBs). Over 1 400 samples of soil and crop tissue were analyzed. This paper presents all the field data and interpretation. The experimental design included eight different sludge treatments and controls, making it possible to study the effects of sludge concentration, sludge loading rate, and sludge application pattern on the fate of PCBs in the soil system. Each treatment was replicated three times, giving thirty test plots in all (24 sludge applications and 6 control plots). Seventy‐nine PCB congeners were detected during the study and the concentration of each PCB congener was measured in the surface soil, corn stover, and corn grain. Surface runoff runoff studies were conducted in 1988 and 1990 and congener‐specific PCB analyses were made on these as well. A first‐order disappearance model, C = C0 exp(− Kt), was appropriate to evaluate the disappearance of PCBs from the surface soil layer. AT is the rate constant for PCB disappearance. Results indicate that the rate constant for disappearance of each individual PCB congener in the soil was independent of the initial PCB sludge concentration, the sludge loading rate, and sludge application pattern. Most of the 2‐, 3‐, and 4‐chlorinated PCB congeners showed significant decreases in their soil concentration with half‐lives in the range of 4 to 58 months. The more highly chlorinated PCBs were more persistent in the sludge amended farmland, but many of them did disappear. The concentration of PCBs in the runoff samples was correlated with surface soil concentration. The PCBs were associated with the runoff sediments and there was no measurable PCB in the liquid portion of the runoff. It was concluded that there is no PCB translocation into either corn grain or corn stover samples. The bioconcentration factor for PCBs in the crop tissues is zero.
Structure of RBC biofilms
Authors: Zahid Waleed M. , Ganczarczyk Jerzy J.
Published: February 2012

ABSTRACT:  A laboratory‐scale model of a rotating biological contactor (RBC) was used to investigate the variations in the structural features of the biofilms formed in the four consecutive compartments of the model during both the early and late stages of the biofilms' development. Microtome sectioning of biofilms showed that, in the early stages of growth, the biofilms were predominantly occupied by nonfilamentous bacteria, and some protozoa were present. However, the biofilms in later stages were mostly filamentous. Biofilm porosity was found to decrease with depth in the biofilm and from one compartment to another, and this decrease was associated with a decrease in pore size. The biofilm porosity/density appeared to be a function of the organic loading. In contrast to biofilms in late‐formation stages, the areal distributions of both microorganisms and pores in biofilms in the early stages of development were relatively uniform through the biofilm. Scanning electron examination of RBC biofilms revealed that biofilm surfaces possessed some fractal properties.
Removal of radionuclides in wastewaters utilizing potassium ferrate (VI)
Authors: Potts Michael E. , Churchwell Duane R.
Published: February 2012

ABSTRACT:  Jar tests were performed to demonstrate the applicability of using potassium ferrate (VI) [K2Fe04] to treat wastewaters containing americium and plutonium. Jar test treatment of tap water spiked with americium and plutonium with potassium ferrate lowered the gross alpha activity from 3.0 × 106 pCi/L to 6 000 pCi/L. An optimum treatment pH of 11.5 to 12.0 was found. At a Department of Energy (DOE) Facility demonstration, potassium ferrate treatment lowered gross alpha activity from 37 000 pCi/L to 40 pCi/L utilizing a two‐step treatment process. The tests performed demonstrated that using potassium ferrate in the aqueous treatment plant at the DOE facility instead of the current treatment chemicals would ensure treatment requirements and discharge limits are met.
Trace metals in the Newport Submarine Canyon, California and the adjacent shelf
Authors: Maurer Don , Robertson George , Gerlinger Tom
Published: February 2012

ABSTRACT:  Trace metals in sediments were measured from the Newport Submarine Canyon (stations = 5), California, and adjacent shelf (stations = 6) including an ocean outfall. Concentrations of total organic carbon, percent silt, percent clay, mercury, zinc, arsenic, chromium, nickel, and lead peaked at a canyon station, and silver, cadmium, and copper peaked at the outfall. Within the canyon silver, cadmium, and copper were positively associated with increasing depth; cadmium was also positively correlated with percent clay. From 1985 to 1989, concentrations of zinc, arsenic, chromium, nickel, copper, and lead declined while silver, cadmium, and mercury remained relatively stable in the canyon. Concentrations of some metals in the canyon (arsenic, chromium, lead, mercury, zinc, and nickel) were generally higher than the adjacent shelf and elsewhere throughout the Southern California Bight. In contrast, silver, cadmium, and copper were higher near an ocean outfall than the canyon. Sources other than the outfall are also probably involved.
Kinetics of acetogenesis and methanogenesis in anaerobic reactions under toxic conditions
Authors: Kim In S. , Young James C. , Tabak Henry H.
Published: February 2012

ABSTRACT:  A method for assessing the impact of toxic organic compounds on the kinetics of acetogenic reactions is presented. The test program involved dosing ethanol‐enriched anaerobic cultures with an isomeric series of chlorophenols and chloroanilines. The effect on the acetogenic conversion of ethanol was monitored by measuring the residual ethanol and acetate in batch serum bottle tests, followed by mathematical analysis to determine coefficients of kinetic and inhibition models. A feature of the presently‐described research program was the use of the specific biomass responsible for acetogenesis and methanogenesis in kinetic models rather than using the total biomass. The distribution of biomass in the ethanol‐enriched test culture was 25.4% hydrogenotrophic methanogens, 41.1% acetoclastic methanogens, and 33.5% ethanol degrading acetogens. The effects of the chloroanilines and chlorophenols on both acetogenesis and methanogenesis appear to be best described as mixed inhibition, and the effects were not clearly related to the position of functional groups. In all cases, the test chemicals were more toxic to the acetoclastic methanogenesis reactions than to the ethanol‐degrading acetogenic reactions.
Membrane biological reactor system for treatment of oily wastewaters
Authors: Knoblock M. D. , Sutton P. M. , Mishra P. N. , Gupta K. , Janson A.
Published: February 2012

ABSTRACT:  The membrane biological reactor (MBR) system consists of a suspended‐growth biological reactor combined with a membrane ultrafiltration unit process. It is particularly attractive in situations where long solids retention times are required, and physical retention and subsequent hydrolysis are critical to achieving biological degradation of pollutants. In order to develop full scale process design information, a large pilot system was operated for eleven months. The pilot project involved assessing performance and developing design information for the system in the treatment of wastewater from two General Motors (GM) facilities. The pilot system results provided a basis for design of a full scale, demonstration MBR system for treatment of industrial wastewater. Case history information is presented in this paper on the design of the MBR system and subsequent operation and performance. Despite certain design issues, the system has met or exceeded performance expectations.
Continuous‐backwash upflow filtration for primary effluent
Authors: England Suzan K. , Darby Jeannie L. , Tchobanoglous George
Published: February 2012

ABSTRACT:  The objective of the research was to investigate the feasibility of continuous‐backwash upflow filtration of primary effluent. Feasibility was assessed on the basis of removal of suspended solids, turbidity, biochemical oxygen demand, and the change in particle size distribution over varying filtration rates. Continuous‐backwash filtration was effective over a wide range of wastewater filtration rates varying from 96 to 264 L/m2 · min (2.4 to 6.6 gal/ft2 · min). An average of 70% of the suspended solids (over an influent range from 8 to 56 mg/L), 46% of the turbidity (over an influent range from 20 to 72 NTU), and 27% of the total 5‐day biochemical oxygen demand (over an influent range from 61 to 101 mg/L) was removed by primary effluent filtration with no subsequent buildup of headloss. Neither the filtration rate nor the influent concentration influenced the removal efficiency for suspended solids, turbidity, biochemical oxygen demand, or affected the particle size distribution of the filtered effluent within the range evaluated.
Performance comparison between activated sludge and fixed film processes for priority pollutant removals
Authors: Clapp L. W. , Talarczyk M. R. , Park J. K. , Boyle W. C.
Published: February 2012

ABSTRACT:  This study compared the performance of activated sludge (AS) and fixed‐film processes in removing organic priority pollutants from a municipal /industrial wastewater. The study employed parallel low and high‐loaded laboratory‐scale AS and biological aerated filter (BAF) reactors. The research focused on the fate of six selected volatile organic compounds (VOCs), although GC/MS scans were also performed to evaluate the fate of other organic priority pollutants. The AS and BAF reactors achieved comparable VOC removals and stripping rates were slightly higher for the AS reactors; biodegradation rates were slightly higher for the BAF reactors. Observed removals, which ranged from 32% for methylene chloride to over 95% for toluene, compared well with removal rates observed in previous studies. Consequential adsorption rates were observed for numerous basic or neutral and pesticide pollutants in both processes.
A two‐phased anaerobic digestion process: Concept, process failure and maximum system loading rate
Authors: Fongastitkul P. , Mavinic D. S. , Lo K. V.
Published: February 2012

ABSTRACT:  This research demonstrated the feasibility of a two‐phase anaerobic sludge digestion process. Process failure and maximum system loading capacity were also investigated. Three‐dimensional plots of chemical oxygen demand (sol), volatile fatty acids (VFA), and mixed liquor volatile suspended soils (MLVSS) profiles of both reactors during maximization and recovery periods (after failure) were made to evaluate the system feasibility. Hydrolysis‐acidification and acetogenesis‐methanogenesis dominated in the acid and methane phase reactors, respectively. Most of the reactions inside the methane‐phase reactor (M‐UASB) occurred in the lower part of the reactor (sludge bed and blanket). A combination of hydraulic and organic overloading of the M‐UASB reactor was a major cause of process failure; this was indicated by MLVSS washout, increase in total VFA concentration, reduction of the system removal efficiency, a drop in pH, an increase in total VFA/alkalinity ratio, a reduction of methane gas production, and an increase in the effluent total VFA. Because of system overloading, there was a shift in the metabolic pathway to a less favorable one, resulting in a shift of VFA producers (acidogens and acetogens) and consumers (methanogens, SRB, and NRB) ratio inside the reactor; this possibly led to a significant accumulation of carbon dioxide and hydrogen gas production. As a result, the partial pressure of hydrogen gas inside the system increased to a certain level, causing a shift in the metabolic pathway and accumulation of propionic acid. The maximum hydraulic loading rates achieved were 1.6 and 0.90 m3/m3 d, equivalent to hydraulic retention times of less than 0.63 and 1.13 days, for the M‐UASB and the whole system, respectively.
Compliance outlook: meeting 40 CFR part 503, class B pathogen reduction criteria with anaerobic digestion
Authors: Stukenberg John R. , Shimp Gary , Sandino Julian , Clark James H. , Crosse John T.
Published: February 2012

ABSTRACT:  The current federal sludge regulations for the first time place limitations on the concentration of pathogens or indicator organisms in sludge and sludge products destined for distribution and marketing and land application. However, there is a general lack of data for assessing the impacts of these new limits on the wastewater industry. To understand better the extent of the compliance problem and the factors that may enable publicly owned treatment works (POTWs) using anaerobic digestion to comply with the new criteria, a survey of treatment plants around the U.S. was undertaken. In addition to data on fecal coliform densities in raw and digested sludge, information was collected on the design and operating characteristics of the 54 digestion facilities that participated in the survey. Based on the analysis of survey responses, it appears that the pathogen reduction criteria under the regulations are not unreasonable and should be achievable by most conventional anaerobic digestion facilities.
Fate of Salmonella typhimurium and total coliforms during bacterial leaching
Authors: Henry J. G. , Prasad D. , Smith B. M.
Published: February 2012

ABSTRACT:  A biological metal extraction (bacterial leaching) process has been developed to extract metals from sludge. Although the removal of metals from sludge is a significant step, any biological hazard must be eliminated before the sludge can be used on land. Earlier studies established that indicator bacteria were not reduced significantly during bacterial leaching. Whether pathogens also would survive or be destroyed in the acidic environment of the bacterial leaching process was not determined. This study was intended to answer this question. A series of batch units performing bacterial leaching was operated with varying sludge concentrations spiked with attenuated Salmonella typhimurium. The concentrations of Salmonella typhimurium and total coliforms in the sludge were determined. Results showed that, although the Salmonella typhimurium population was eliminated within 7 hours (at pH 4.0, an aeration rate of 100 mL of air per minute per litre of sludge, and at a room temperature of 20 to 25 °C), the total coliforms persisted during the leaching period of 10 days. The inactivation of the Salmonella typhimurium appeared to be independent of the suspended solids concentration in the leaching units, unlike the survival of total coliforms which was found to be a function of the suspended solids concentration. At suspended solids concentrations of about 40 g/L, the total coliforms persisted, whereas after 5 days, coliforms were not detected in units containing about 10 g SS/L.
Constructed reed beds: A cost‐effective way to polish wastewater effluents for small communities
Authors: Green M. B. , Upton J.
Published: February 2012

ABSTRACT:  This paper outlines the increasing need for effluent polishing in the United Kingdom. It puts that need in the context of the more than 700 sewage treatment works serving populations of less than 2 000 in Severn Trent Water's area of the English Midlands. Constructed reed beds have their place in a design selection matrix. At the end of 1991, they were in use at 12 sites and more than 60 are programmed for completion in 1992. The design and construction of reed beds used for effluent polishing is described. Detailed results are given for five of the works commissioned between 1987 and late 1991. All produce high quality effluents in terms of BOD5 and total suspended solids. A cost comparison between reed beds and modular sandfilters, based on recent contract prices, is shown. Estimates of maintenance, labor costs, and asset life are included.
A comparison of three artificial substrate samplers: Macroinvertebrate densities, taxa richness, and ease of use
Authors: Kirk Edwin J. , Perry Sue A.
Published: February 2012

ABSTRACT:  Density, taxa richness, and composition of macroinvertebrates collected by three types of samplers were compared to determine their relative effectiveness for sampling in large rivers. Three multiplate samplers and three gravel basket samplers were deployed in the water column, and three large‐cobble basket samplers were deployed on the river bottom. Two sites were sampled at monthly intervals from October 1988 to November 1989. Macroinvertebrate densities were significantly (p < 0.05) different among the three sampler types. Mean monthly macroinvertebrate density was highest on the multiplate samplers at both sites—1 742 and 1 239 macroinvertebrates/m2 and was lowest on the large‐cobble basket samplers at both sites—174 and 266 macroinvertebrates/m2. Mean monthly macroinvertebrate density was moderate on the gravel basket samplers at both sites—278 and 472 macroinvertebrates/m2. Mean monthly taxa richness was generally higher on the gravel basket and large‐cobble basket samplers than on the multiplate samplers. Multiplate samplers collected larger numbers of Chironomidae, Oligochaeta, Trichoptera, and Ephemeroptera, but were least effective at collecting Turbellaria, burrowing Ephemeroptera, Odonata, and Mollusca. Gravel basket samplers collected larger numbers of Chironomidae, Oligochaeta, Crustacea, and Ephemeroptera, and in addition collected more Odonata and Mollusca. Large‐cobble basket samplers collected more burrowing Ephemeroptera.
Estimating semivolatile organic compound emission rates and oxygen transfer coefficients in diffused aeration
Authors: Hsieh Chu‐Chin , Babcock Roger W. , Stenstrom Michael K.
Published: February 2012

ABSTRACT:  A relationship developed previously to estimate emissions from surface aerated reactors that accounts for both gas and liquid phase mass transfer resistances is extended to reactors with diffused aeration systems. The method accurately predicts the observed emission rate of twenty volatile organic compounds with a wide range of Henry's coefficients over a wide range of hydrodynamic conditions. The liquid‐and gas‐phase mass transfer coefficients are estimated.
Aerobic biodegradation potential of photoprocessing wastewaters
Authors: Pavlostathis Spyros G. , Morrison Douglas
Published: February 2012

ABSTRACT:  Currently, over 99% of all photoprocessing laboratories in the U.S. discharge directly to publicly owned treatment works (POTWs) after using various recovery methods. The purpose of this research was to investigate any potential adverse effects of photoprocessing effluents on the activated sludge process. Effluents from two commonly used photoprocesses were tested. These effluents were simulated in the laboratory and fed to fill‐and‐draw activated sludge reactors at loading levels less than or equal to 20% by volume along with a synthetic base feed. Conventional wastewater treatment parameters along with major photoeffluent constituents, such as ethylene diamine tetraacetate (EDTA), sulfur, and nitrogen species, were monitored. Results indicate that EDTA was recalcitrant and accounted for a significant fraction of the effluent COD. A significant fraction of the reduced sulfur species were oxidized to sulfate resulting in alkalinity consumption and a pH reduction. All activated sludge reactors showed a decrease in influent ammonia concentration and production of nitrate or nitrite. Up to 61% photoeffluent COD removal was achieved by the fill‐and‐draw activated sludge reactors. Such results demonstrate the potential of aerobic biological processes in the treatment of photoprocessing wastewaters and warrant further study.
Anaerobic biodegradation potential of photoprocessing wastewaters
Authors: Pavlostathis Spyros G. , Sridhar K.
Published: February 2012

ABSTRACT:  The anaerobic biodegradation potential of photoprocessing effluents and their effect on the anaerobic digestion of biological sludge generated from the aerobic treatment of photoprocessing wastewaters were investigated. Simulated C‐41 photoprocessing wastewaters were subjected to an anaerobic toxicity test using the serum bottle technique. Unacclimated, anaerobic sludge inocula were used and the test solutions consisted of photoprocessing wastewaters and readily degradable organic substrates. Concentrations of photoeffluents considerably higher than those expected to reach municipal wastewater treatment plants initially depressed the production of methane, mainly because of competition between sulfate reducing and methanogenic bacteria. After prolonged incubation, methanogenesis recovered. Biological sludge generated by laboratory‐scale activated sludge reactors with and without photoeffluents was fed to anaerobic digesters without adverse effects. The digesters fed sludge from the aerobic treatment of photoeffluents achieved about 14% higher digestibility than did the digester fed with sludge never exposed to the photoeffluents. For photoeffluent levels expected to reach municipal wastewater treatment plants, no adverse effects on anaerobic digestion are expected.
Optimization of a nitrogen‐removing biological wastewater treatment plant using on‐line measurements
Authors: Sorensen John , Thornberg Dines E. , Nielsen Marinus K.
Published: February 2012

ABSTRACT:  The installation of continuous on‐line measurements of ammonium and nitrate in the aeration tanks of a nitrogen removing activated sludge plant has reduced the nitrate amount in the effluent by 60%. This corresponds to a drop in the average total nitrogen concentration in the effluent from 7.8 mg/L to 5.1 mg/L. The operation of the nitrogen removal process and thereby the effluent concentrations has become more stable. By combining operational changes in the biosorption with on‐line control of the process, it is possible to maintain full and stable denitrification at a BOD/N ratio of 3 to 4 without the use of any external carbon source, despite great variations in the loading of the plant. Monitoring of the microscopic characteristics of the sludge can be closely correlated with macroscopic characteristics such as sludge volume index.
Investors', Auditors', and Lenders' Understanding of the Message Conveyed by the Standard Audit Report on the Financial Statements
Authors: Asare Stephen Kwaku , Wright Arnold M.
Published: February 2012

SYNOPSIS

The purpose of this study is to evaluate the extent to which there are communication gaps among auditors and two user groups in their understanding of the messages conveyed by the standard audit report on the financial statements (SAR). Auditors, bankers, and nonprofessional investors reviewed background information on a hypothetical company that had received a SAR. Compared to auditors, users consider the SAR to be more important in assessing fraud risk even though they assess a lower likelihood that auditors have detected fraud. Further, the SAR gives users a significantly higher level of confidence in the company's management, investment soundness, and accomplishment of strategic goals than auditors. We also find several instances where the auditors and bankers differed from the nonprofessional investors in the interpretation of technical terms in the SAR, suggesting a between-user disagreement in interpreting the technical terms. Taken together, the results suggest that there are important differences between auditors and users in their understanding of the broad messages conveyed by the SAR (i.e., roles, responsibilities, and conclusions of an audit), and those differences are not driven by disagreements in interpreting the technical terms in the SAR.
Factors Affecting the Central Corneal Thickness in Nepalese Population
Authors: Godar ST , Kaini KR , Khattri JB
Published: February 2012

Background: Intra Ocular Pressure (IOP) is an important parameter for the detection and monitoring of glaucoma. Central corneal thickness (CCT) can influence the IOP estimated with Goldmann tonometry. A thick cornea overestimates the IOP and thin underestimates it. So, decreased CCT may lead to underdiagnosis and undertreatment of glaucoma and increased CCT may lead to overdiagnosis and overtreatment of glaucoma. The aim of the study is to identify the factors affecting the CCT in Nepalese population. Methods: A hospital based cross-sectional study which enrolled 152 subjects from period of January 2009 to May 2010. All subjects underwent ophthalmological examinations. CCT was measured with ultrasonic pachymeter and intraocular pressure was measured with Goldmann applanation tonometer. Results: The mean±SD CCT of right and left eye was 538±32 and 540±30μm respectively. CCT decreased with increasing age. Age and intra ocular pressure was significantly correlated with CCT. There was no significant correlation of gender and ethnicity with CCT. Conclusion: CCT decreased with increasing age. CCT was significantly correlated with age and intra ocular pressure but not with gender and ethnicity. Keywords: Nepalese; central corneal thickness; ultrasound pachymeter DOI: http://dx.doi.org/10.3126/njms.v1i1.5788   Nepal Journal of Medical Sciences. 2012; 1(1): 7-10.
Socio-demographic Characteristics and Diagnostic Profile of Patients Attending Psychiatric OPD of a Private Hospital in Western Region of Nepal
Authors: Khattri JB , Godar ST , Thapa P , Ramesh K , Chakrabortty PK , Thapa BB
Published: February 2012

Background: Mental health services in Nepal are limited and there is a scarcity of epidemiological studies in our country. The present study is done with the aim to study the socio-demographic characteristic and diagnostic profile of patients attending the psychiatric OPD. Methods: This is a retrospective study where case records of all new patients, diagnosed to be suffering from Mental and Behavioral disorders according to Chapter V (F) of ICD-10, who attended the OPD from July 2011 to December 2011, were included in the study. Results: Maximum patients fall in the younger age group and are females. The patients were found to be suffering from neurotic, stress-related and somatoform disorders (35.4%) followed by mood disorder (18.3%), schizophrenia, schizotypal and delusional disorders (17.4%) and mental and behavioral disorders due to psychoactive substance use (9.7%). Conclusion: Mental disorders comprise a wide variety of disorders and affect the most productive age group suggesting the need for early identification and prompt management. Keywords: ICD-10 DCR; psychiatric OPD; psychiatric morbidity; neurotic disorders DOI: http://dx.doi.org/10.3126/njms.v1i1.5790 Nepal Journal of Medical Sciences. 2012; 1(1): 15-18
Management of Head Injury by General Surgeons in a General Hospital
Authors: Ghimire P , Yogi N , Acharya GB
Published: February 2012

Background: Head injury is one of the common causes of surgical admission in Western Regional Hospital, Pokhara, Nepal. With no neurosurgeons available, most of the cases are managed effectively with adequately trained general surgeons. The aim of the study is to study the epidemiology, incidence and pattern of head injury and their outcome in a setting of a general hospital where they were managed by general surgeons. Methods: This is a prospective analytical study of 1847 head injury patients. The study defines the patterns of head injury, their management by general surgeons and outcome in surgery ward, Western Regional Hospital, Pokhara for about five years (1999 to 2003). Results: Head injury comprised 15.5% (1847) of total admissions (11901) in surgery ward. Out of those, 80.5% (1487) were mild, 10.4% (192) moderate and 9% (168) severe head injury cases, based on Glasgow coma scale. Majority of cases (42.1%) were young adults between 21-40 years. 70% (1294) of cases were male and 30% (553) were female. 7.5% (138) cases were associated with skull fractures. Most of the cases showed good recovery. Only 2% required surgery; 3.7% were referred; 2.8% died and 0.8% left against advice. Conclusion: Most of the cases of head injury can be managed by general surgeon in a General Hospital provided basic facilities like high dependency unit, Intensive care unit and a dedicated team are available. Keywords: Glasgow Coma Scale; head injury; traumatic brain injury DOI: http://dx.doi.org/10.3126/njms.v1i1.5791   Nepal Journal of Medical Sciences. 2012; 1(1): 19-22
Socio-demographic Features of Mothers in Relation to Duration of Breastfeeding in Manipal Teaching Hospital, Pokhara, Nepal
Authors: Basnet S , Gauchan E , Malla K , Malla T , Koirala DP , Rao KS , Sedai Y , Saha R
Published: February 2012

Background: It was noticed by the authors that the patients attending the Pediatrics Department were being breastfed for a longer duration than the recommended two years by the World Health Organization (WHO). This study was undertaken to see the exact duration of breastfeeding of the children who were being treated at the hospital. Method: This was a prospective study carried out from April 2010 to March 2011 in 500 children who were treated at Manipal Teaching Hospital, Pokhara, Nepal. Other demographic features such as the mother’s age, occupation, education, ethnicity and child’s sex were also some of the factors which were studied to see if these factors influenced the duration of breastfeeding. Results: Our study revealed that the median age of breastfeeding among the children studied was 43 months. Out of the 500 mothers who were interviewed 159 of them breastfed their child beyond the age of 60 months (5 years). In addition, we did not find any statistically significant gender discrimination with regards to the breastfeeding duration. Conclusion: This study shows that the studied population has been breastfed for longer duration than the recommended guideline stipulated by the WHO. The duration of breastfeeding seen in this study is higher than shown in previous studies. Keywords: Breastfeeding; extended breastfeeding; socio-demographic DOI: http://dx.doi.org/10.3126/njms.v1i1.5793   Nepal Journal of Medical Sciences. 2012; 1(1): 27-30
Gender Difference in Frequency of Conventional Risk Factors in Patients with Acute Coronary Syndrome Admitted in Manipal Teaching Hospital, Pokhara, Nepal
Authors: Parajuli M , Maskey A , Kohli SC , Shrestha UK
Published: February 2012

Background: Acute coronary syndrome (ACS) is the major manifestation of coronary artery disease (CAD), which is a major killer of mankind. The modifiable risk factors for CAD may have different impact on men and women, which may also differ in different population groups. Identification and control of conventional risk factors is expected to result in a decline in incidence of CAD similar to that seen in western industrialized countries. Method: A retrospective study of 232 consecutive patients admitted to Manipal Teaching Hospital, Pokhara between September 2009 to December 2010 by studying their hospital records for following conventional risk factors of CAD viz Body mass index, current cigarette smoking, hypertension, excessive alcohol use, diabetes mellitus and dyslipidemia. The results were analyzed by SPSS 16. Results: The important modifiable risk factors in order of descending frequency were high BMI, smoking, hypertension, excessive alcohol use, raised total cholesterol, raised triglyceride and diabetes mellitus. Smoking and excessive use of alcohol were seen in statistically significant higher percentage of cases in males. Our study further revealed that in females, unstable angina whereas in males ST elevation myocardial infarction (STEMI) was present in statistically significant higher number of cases. Conclusion: Our study showed a statistically significant higher incidence of smoking and excessive alcohol use as risk factors for ACS in males. It was also seen that in females unstable angina and in males STEMI was present in statistically significant higher number of cases. Keywords: Acute coronary syndrome; Coronary artery disease; gender difference; risk factor DOI: http://dx.doi.org/10.3126/njms.v1i1.5794   Nepal Journal of Medical Sciences. 2012; 1(1): 31-34
The Pattern of Ocular Morbidity, Findings from a Study Conducted in Western Remote Hilly Region of Nepal
Authors: Bastola P
Published: February 2012

Background: There is a lack of study in the pattern of ocular morbidity in western hilly region of Nepal. Therefore a study was carried out to find out the pattern of ocular morbidity, in various age groups in a diagnostic, screening and treatment camp (DST) held in a western hilly remote region of Nepal. Methods: A descriptive, cross sectional study was done to find out the pattern of ocular morbidity in a western hilly region of Nepal. All the cases included in the study were examined thoroughly from Ophthalmological perspective and a diagnosis was made. Patients needing treatment both medical as well as surgical were advised accordingly and referred when indicated. Results: A total of 712 eyes of 356 cases were examined in this study. The range of the age varied from two months of life to 91 yrs of age. Age wise most number of cases were in the school going age group accounting for almost 80% of all the cases. The commonest ocular morbidity encountered were refractive error (15.4%), dry eyes, ocular allergy, followed by cataract. Majority of the cases had both dry eyes and ocular allergy. While 70 eyes of 35 patients had no ocular morbidity. Conclusion: The lower prevalence of age related cataract was due to the extensive cataract surgical coverage provided in the region by various organizations and because of lesser number of cases examined above the age of 40 years. Finding of just three cases of Xerophthalmia (X2B), pointed out towards the success of extensive Vitamin A supplement program run by the ministry of health. Keywords: Refractive error; dry eyes; ocular allergy; cataract DOI: http://dx.doi.org/10.3126/njms.v1i1.5795   Nepal Journal of Medical Sciences. 2012; 1(1): 35-38
Alcohol Dependence Syndrome Among Older Adults Attending Psychiatry OPD of a Private Hospital in Western Region of Nepal
Authors: Khattri JB , Poudel BM , Godar ST , Ramesh K , Chakrabortty PK , Thapa BB
Published: February 2012

Background: Alcohol use disorders in elderly people are common and associated with considerable morbidity. The objective is to estimate the prevalence of alcohol dependence syndrome among elderly patients attending psychiatric outpatient department of a private hospital in Western region of Nepal. Methods: A total of 80 elderly patients aged 65 years and above who attended the psychiatry outpatient department of Fewa City Hospital and Research Centre, Pokhara, Nepal were included in the study. A semistructured Performa was used to record the sociodemographic variables and the diagnosis was made according to ICD-10 Diagnostic Criteria for Research. Results: Five percent of the samples were diagnosed with alcohol dependence syndrome. The male to female ratio was 3:1. Conclusion: Results show high rates of alcohol dependence among the elderly population attending the outpatient department of a private hospital in Western Region of Nepal. Keywords: Alcohol dependence syndrome; older adults; psychiatric OPD DOI: http://dx.doi.org/10.3126/njms.v1i1.5796   Nepal Journal of Medical Sciences. 2012; 1(1): 39-41
Old and New Players in Oral Antiplatelet Therapy in Treatment of Acute Coronary Syndrome
Authors: Kohli SC
Published: February 2012

Oral antiplatelet therapy plays an important role in treating patients with acute coronary syndrome (ACS), including patients with unstable angina (UA), non-ST segment elevation myocardial infarction (NSTEMI) and patients with ST-segment elevation myocardial infarction (STEMI). All antiplatelet drugs in addition to inhibiting acute arterial thrombosis have danger of interfering with the physiologic role of platelet hemostasis. Bleeding is a major factor in evaluating the utility of available and upcoming antiplatelet drugs and their combination regimes. The role of anti platelet agents in the treatment of ACS has undergone significant changes over the past several years. Aspirin, thienopyridines, and glycoprotein (GP) IIb/IIIa inhibitors are now standard parts of the treatment of STEMI, NSTEMI and UA whether an early invasive or an initial conservative strategy is chosen. Antiplatelet drugs have an important role in secondary prevention in the patients of ischaemic heart disease. Keywords: Acute Coronary Syndrome; antiplatelet therapy; thienopyridines. DOI: http://dx.doi.org/10.3126/njms.v1i1.5799   Nepal Journal of Medical Sciences. 2012; 1(1): 49-55