bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzyme‐Catalyzed Removal of Phenol from Refinery Wastewater: Feasibility Studies
Authors: Ibrahim M.S. , Ali H.I. , Taylor K.E. , Biswas N. , Bewtra J.K.
Published: September 2006

Phenols are present in petroleum refining wastewater. An enzymatic method for removing phenols from industrial aqueous effluent has been developed in the past several years. In this method, a peroxidase enzyme catalyzes the oxidation of phenol by hydrogen peroxide generation of phenoxyl radicals. These radicals diffuse from the active center of the enzyme into solution and react nonenzymatically to eventually form higher oligomers and polymers, which can be removed from wastewater by conventional coagulation and sedimentation or filtration. In this study, Arthromyces ramosus peroxidase (ARP) was applied to treat a petroleum refining wastewater containing 2 mM (188 mg/L) phenol in a batch and continuous‐flow system. The latter consisted of a plug‐flow reactor (PFR) where the reaction took place between phenol and hydrogen peroxide catalyzed by the enzyme in the presence of polyethylene glycol (PEG). A flocculation tank followed the PFR where alum and sodium hydroxide were added and then the polymers formed were settled in a sedimentation tank and removed from the system. Most (95 to 99%) of the phenol was removed by the same dose of ARP required for the treatment of synthetic wastewater containing an equal amount of phenol. Polyethylene glycol, as an additive, reduced enzyme inactivation and consequently reduced the enzyme dose and the cost of the treatment process. Step feeding of hydrogen peroxide was not effective in reducing the enzyme requirement. A significant removal of chemical oxygen demand was achieved when using PEG to reduce the enzyme dose.
Modeling of Soluble Microbial Products in Anaerobic Digestion: The Effect of Feed Strength and Composition
Authors: Barker Duncan J. , Stuckey David C.
Published: September 2006

Continuously stirred tank reactors (CSTRs) and fill‐and‐draw reactors were used to investigate soluble microbial product (SMP) production during anaerobic digestion. Continuously stirred tank reactors with a glucose feed at three different strengths (5, 10, and 20 g chemical oxygen demand [COD]/L) and fill‐and‐draw reactors with four different feed compositions (glucose, glycerol, lactic acid, and starch at 10 g COD/L) were used with a solids retention time (SRT) of 15 days. The SMP production ranged from 102 to 588 mg COD/L for the glucose‐fed CSTRs and between 157 and 1192 mg COD/L for the fill‐and‐draw reactors and was found to increase with increasing influent COD (S0). Normalized production of SMPs (SMP/S0) ranged from 1.4 to 3% for the CSTRs and 12.0, 1.7, 14.7, and 3.6% for the glucose‐, glycerol‐, lactic acid‐, and starch‐fed reactors, respectively. A model incorporating SMP production and degradation was fitted to results from carbon‐14 tracer studies in all of the reactors. The best‐fit parameters from this model revealed that the type of SMP that dominates in any particular system depends not only on the strength of the feed but also on the composition of the feed and the type of reactor.
Kinetics of the Alkaline Hydrolysis of Nitrocellulose
Authors: Christodoulatos Christos , Su Tsan‐Liang , Koutsospyros Agamemnon
Published: September 2006

Cellulose nitrate (nitrocellulose) is an explosive solid substance used in large quantities in various formulations of rocket and gun propellants. Safe destruction of nitrocellulose can be achieved by alkaline hydrolysis, which converts it to biodegradable products that can then be treated by conventional biological processes. The kinetics of the alkaline hydrolysis of munitions‐grade nitrocellulose in sodium hydroxide solutions were investigated in completely mixed batch reactors. Experiments were conducted using solutions of alkaline strength ranging from 0.1 to 15% by mass and temperatures in the range of 30 to 90 °C. Regression analysis of the kinetic data revealed that alkaline hydrolysis of nitrocellulose is of the order 1.0 and 1.5 with respect to nitrocellulose and hydroxide concentration, respectively. The activation energy of the hydrolysis reaction was found to be 100.9 kJ/mol with a preexponential Arrhenius constant of 4.73 × 1013. Nitrite and nitrate, in a 3:1 ratio, were the primary nitrogen species present in the posthydrolysis solution. The kinetic information is pertinent to the development and optimization of nitrocellulose chemical–biological treatment systems.
Implications of Industrial Loads for Ammonia Pollution in an Urban Lake
Authors: Effler Steven W. , Gelda Rakesh K. , (Brooks) Matthews Carol M.
Published: September 2006

The recent history of loading of total ammonia (T‐NH3) and organic nitrogen (N) from a pharmaceutical manufacturing facility to a municipal treatment plant (Metro) in Syracuse, New York, and the discharge of these constituents from Metro to N‐polluted Onondaga Lake is documented. Further, the benefit of the implementation of pretreatment at the pharmaceutical plant, and the effect of an upset event at this treatment facility on loading to Metro and the lake and in‐lake concentrations are also documented. Models are used as analytical tools to couple loading and in‐lake concentrations, to delineate the role that this pharmaceutical facility has played in the lake's ammonia pollution problem, and to evaluate the potential implications of future pretreatment upset events for the success of a rehabilitation program that is underway for the lake. The responsiveness of the lake to reductions in external loading is established by the lower T‐NH3 concentration observed in the upper waters of the lake in the spring of 1999. Model analysis demonstrates this reduction was primarily (∼ 75%) because of the decrease in loading from the pharmaceutical facility achieved by pretreatment. An abrupt increase in loading in May 1999 associated with an upset event at the pretreatment facility caused a corresponding increase in the T‐NH3 concentration of the lake of approximately 0.5 mg N/L. Model projections demonstrate that the load from the pharmaceutical plant before construction of the pretreatment facility exacerbated the lake's ammonia problems by increasing the occurrence and margin of violations of the toxicity standard. Continued upset events at the pretreatment plant could compromise the lake rehabilitation program.
Seasonal Pathogen Removal by Alternative On‐Site Wastewater Treatment Systems
Authors: Pundsack Jonathan , Axler Richard , Hicks Randall , Henneck Jerald , Nordman Delwin , McCarthy Barbara
Published: September 2006

Subsurface‐flow constructed wetlands, sand filters, and peat filters near Duluth, Minnesota, were studied to determine their seasonal performance for removing pathogens from wastewater. Influent was a high‐strength septic tank effluent (mean values of 5‐day biochemical oxygen demand, total nitrogen, and total phosphorus were 294, 96, and 15 mg/L, respectively) at the Natural Resources Research Institute's alternative treatment system test facility in northern Minnesota. Each treatment system was inoculated with cultures of Salmonella choleraesuis (serotype typhimurium) for 5 to 7 consecutive days in summer and winter during 1998 to 1999. After the seeding, outflow samples were taken until Salmonella counts were sustained at background levels. The removal of Salmonella was calculated for each system, although the exact removal mechanisms were not determined. During the summer, the wetlands removed 99.6 to 99.999 4% (2.4 to 5.3 log10 reduction) of the culturable Salmonella. The sand filters demonstrated a greater than 7 log10 removal of Salmonella cells, whereas the peat filters were responsible for a greater than 8 log10 loss of cells. Fewer Salmonella cells were removed by all of these systems during the winter, although the pattern of removal was similar to their summer operation. During the winter, the wetlands and sand filters removed greater than 1 log10 of culturable cells, but the peat filters were responsible for a greater than 5 log10 loss of cells. Fecal coliform removal patterns reflected those for Salmonella by treatment systems for summer and winter periods. Based on Salmonella and fecal coliform removal, the peat filters operated most effectively followed by the sand filters and the constructed wetlands.
Effects of pH on the Rates of Aerobic Metabolism of Phosphate‐Accumulating and Glycogen‐Accumulating Organisms
Authors: Filipe Carlos D.M. , Daigger Glen T. , Grady C.P. Leslie
Published: September 2006

The effect of pH on the aerobic metabolism of phosphorus‐accumulating organisms (PAOs) and glycogen‐accumulating organisms (GAOs) was studied using aerobic batch experiments performed at pH 6.5, 7.0, and 7.5. For PAOs, the rates of phosphate uptake, polyhydroxy‐alkanoates consumption, and biomass growth observed at pH 6.5 were 42, 70, and 53%, respectively, of the rates observed at pH 7.0. In contrast, the rates for GAOs were relatively independent of pH for the range tested. The results suggest that the stability of biological excess phosphorus removal (BEPR) is strongly dependent on the pH in the aerobic zone. If the pH is low, growth of PAOs will be inhibited whereas the growth of GAOs will be only mildly affected. This may lead to the proliferation of GAOs in BEPR systems, resulting in reduced phosphorus removal.
pH as a Key Factor in the Competition Between Glycogen‐Accumulating Organisms and Phosphorus‐Accumulating Organisms
Authors: Filipe Carlos D.M. , Daigger Glen T. , Grady C.P. Leslie
Published: September 2006

The effects of pH on the anaerobic metabolism of glycogen‐accumulating organisms (GAOs) and phosphorus‐accumulating organisms (PAOs) were compared using models for the kinetics of acetate uptake. The comparison revealed that GAOs take up acetate faster than PAOs when the pH of the anaerobic zone is less than 7.25, but that PAOs remove acetate faster than GAOs at pHs greater than 7.5. It was also found that the growth efficiencies of the two organisms are similar. Furthermore, the amount of polyhydroxy‐alkanoates available after replenishment of the polymers used during acetate uptake under anaerobic conditions is similar for the two organisms, making GAOs highly competitive in nutrient removal systems. The effects of pH on the competition between the two organisms were demonstrated during the operation of a laboratory‐scale sequencing batch reactor. When the overall pH of the system was low, poor phosphate removal was observed. When the pH of the system was allowed to increase to a maximum of 7.5, phosphate removal improved, but was still incomplete. Total removal was only achieved when the pH of the system was never allowed to drop lower than 7.25. After the minimum pH in the system was increased, total removal of phosphate was achieved in 14 days. The results showed that pH control is a promising strategy for minimizing the accumulation of GAOs and increasing the reliability of biological excess phosphorus removal systems.
Particle Effects on Ultraviolet Disinfection of Coliform Bacteria in Recycled Water
Authors: Jolis Domènec , Lam Curtis , Pitt Paul
Published: September 2006

Pilot‐ and bench‐scale coliform inactivation tests with UV irradiation were used to show how suspended solids remaining in filtered secondary effluent affect the efficiency of the UV disinfection process. Observed kinetic inactivation rates decreased with increasing suspended particle sizes of 7 μm or larger present in tertiary effluent. First‐order inactivation rates estimated from collimated beam dose–response curves for discrete ranges of UV doses were substantially different, which should caution researchers not to compare inactivation data obtained with largely dissimilar UV doses or suspended particle distributions. A dose of approximately 800 J/m 2 was identified as the minimum dose that will consistently meet the California wastewater reclamation coliform criterion when applied to in‐line filtration effluent.
A Test for Predicting Propensity of Activated Sludge to Acute Filamentous Bulking
Authors: Séka M. Arsène , Cabooter Sofie , Verstraete Willy
Published: September 2006

Filamentous bulking is a solid–liquid separation problem well known to activated‐sludge plant operators. The use of curative additives is a rather delicate solution and the tools developed to anticipate it seem limited. To complement existing sludge sedimentation monitoring tools, a new test to assess the propensity of activated sludge for filamentous bulking was developed. It consists of challenging the sludges by feeding them under conditions favoring filamentous bacteria for 24 hours. The effects of such an acute treatment on sludge settleability is subsequently assessed through a simple sludge volume (SV30) measurement with reference to a control. The sludge can then be evaluated as prone to bulking (unstable sludge) or not (stable sludge). Such a test can be used to predict the occurrence of filamentous bulking in activated‐sludge treatment plants. This so‐called acute bulking test requires simple equipment and can be done by any wastewater treatment plant operator.
Photochemical Production of Hydroxyl Radical from Aqueous Iron(III)–Hydroxy Complex: Determination of Its Reaction Rate Constants with Some Substituted Benzenes Using Deoxyribose‐Thiobarbituric Acid Assay
Authors: Joseph Jiju M. , Luke Teena L. , Aravind Usha K. , Aravindakumar Charuvila T.
Published: September 2006

Hydroxyl radical (•OH) production, mediated by UV light, from aqueous ferric perchlorate was investigated at low pH using a deoxyribose–thiobarbituric acid (–TBA) assay. The rate of production of •OH was found to be dependent on the irradiation time. Addition of suitable substrates such as substituted benzenes can compete for the reaction of •OH with deoxyribose, leading to a decreased yield of TBA chromogen formed from the deoxyribose–TBA assay. The second‐order rate constants of the added substrates can be determined from such a simple competition kinetic method. The second‐order rate constants for the reaction of •OH with a number of substituted benzenes were determined using this method and the values were compared with the reported rate constants using pulse radiolysis technique. The values determined using the present method (1 to 8 × 109 dm3/mol·s) are in good agreement with those reported by use of the pulse radiolysis technique. It is proposed that the photoproduction of •OH from aqueous ferric perchlorate coupled with deoxyribose–TBA assay is a simple and efficient method for determination of rate constants for the reaction of •OH with a variety of substituted benzenes that are known to be organic water contaminants.
Development of Chronic Aquatic Water Quality Criteria and Standards for Silver
Authors: Ford Libby
Published: September 2006

U.S. Environmental Protection Agency (EPA) is updating its aquatic life ambient water quality criteria (aqAWQC) for a number of parameters, including silver. The silver aqAWQC was last issued in 1980. At that time only an acute aqAWQC was established. With the increased reliance on water quality criteria to drive and prioritize the United State's efforts to improve water quality, the scientific basis of new and modified water quality criteria must be both strong and transparent. Although few, if any, natural waters in the United States have suffered water quality impairments because of silver, the lack of valid silver chronic toxicity data in combination with the misapplication of the current U.S. EPA guidelines on deriving chronic aqAWQC could lead to derivation of chronic criteria (by U.S. EPA) and chronic standards (by states, tribes, etc.) that are not supported by scientific data. This misapplication could result in U.S. EPA and the states listing many waters as impaired by silver where, in fact, no silver‐related water quality problem exists. This Research Note reviews available information on studies of both acute and chronic silver toxicity to aquatic organisms, as well as U.S. EPA's 1985 procedure for adopting chronic water quality criteria. It identifies existing gaps in the underlying research data base and identifies additional work necessary to derive valid chronic water quality criteria and standards for silver.
Nonlinear Estimation of Microbial and Enzyme Kinetic Parameters from Progress Curve Data
Authors: Goudar Chetan T. , Devlin John F.
Published: September 2006

A computer program (BIOKINFIT) was developed to estimate microbial and enzyme kinetic parameters from progress curve data by nonlinear regression. BIOKINFIT overcomes the limitations associated with parameter estimation in nonlinear equations that are implicit in the dependent variable by numerically approximating the substrate concentration in the integrated kinetic expressions. The simplex method was used to minimize the error between experimentally observed and theoretically predicted substrate depletion data. The robustness of this approach was initially verified using synthetic substrate depletion data that were characterized by either simple or relative errors of known magnitude. Subsequently, previously published data from three different experiments including the pyruvate kinase reaction, 2‐chlorophenol biodegradation, and glucose uptake by Penicillium chrysogenum were used to verify the utility of the present approach for kinetic parameter estimation. In all cases, experimental substrate depletion data were accurately described by the theoretical curves and kinetic parameter estimates obtained in this study using the simplex method were in close agreement with those reported previously. BIOKINFIT, available free of charge on request, offers a convenient and robust method of analyzing progress curve data in implicit kinetic expressions.
Relationship Between Oxygen Transfer Rate and Airflow for Fine‐Pore Aeration Under Process Conditions
Authors: Iranpour Reza , Stenstrom Michael K.
Published: September 2006

Although feedback systems that control the air supply to aeration tanks inherently incorporate some assumption about oxygen transfer response to changes in airflow, it is rare to measure this relationship under process conditions. This paper reports measurements of oxygen mass‐transfer curves (MTCs) for a tank at the Tillman Water Reclamation Plant in Los Angeles, California. The curves were obtained by measuring the oxygen transfer efficiency (OTE) at selected points for several set values of airflow while the plant was operating. They approximate inverted parabolas because increasing the airflow increases the amount of oxygen supplied by the blowers, but decreases the OTE, which is the fraction of the supplied oxygen that actually enters the water. Data were recorded from both recently cleaned diffusers and ones that were moderately to severely fouled. The peaks in the curves from the fouled diffusers are at or below the midpoints of the observed ranges of airflows. Hence, there is only a narrow range of usable airflows between the lower limit, determined by the manufacturer of the diffusers, and the peak of the MTC, which is the maximum amount of oxygen that can be supplied. The peaks for the cleaned diffusers are higher, which allows more ability to adjust to changing biological loads. These results show that existing dissolved oxygen control systems may not be adequate and that fouling may reduce not only the overall efficiency of an aeration system but its ability to respond to changes in the biological load. The measurements also provide some insight to the limitations of using sparsely distributed dissolved oxygen sensors to control the aeration process and the excess costs that are incurred by the consequent need to compensate for uncertainty with extra air. However, additional testing is needed to determine whether the present results are aberrant or typical of tanks with fouled or cleaned diffusers.
Evaluation of the Potential Effects of Equalization on the Performance of Biological Phosphorus Removal Systems
Authors: Filipe Carlos D.M. , Meinhold Jens , Jørgensen Sten‐B , Daigger Glen T. , Grady C.P. Leslie
Published: September 2006

Experimental data confirming that the phosphorus removal efficiency in biological excess phosphorus removal (BEPR) systems temporarily decreases when the amount of volatile fatty acids (VFAs) added in the anaerobic phase is suddenly increased are presented. This decrease in efficiency results from the fact that acetate uptake is a rapid process and that the phosphate concentration at the end of the anaerobic phase increases rapidly. Because of the nonlinear dependence of the phosphate uptake rate on the poly‐β‐hydroxy‐alkanoate (PHA) content of phosphate‐accumulating organisms (PAOs), the increase in PAO PHA content associated with VFA uptake is not able to cause a proportional increase in the rate of phosphate uptake. This causes a temporary imbalance between phosphate release and uptake, leading to lower phosphate removal efficiency. The VFA loading to full‐scale BEPR systems is not constant throughout the day, and temporary imbalances such as the ones imposed in the batch tests can occur in full‐scale systems. The effect of diurnal variations in loading was demonstrated through simulation of the behavior of an A/O™ system receiving a time‐variable influent. Equalization is proposed as a method to diminish the potential for imbalances between phosphate release and uptake by avoiding sudden increases of VFA loading to the plant. Significant improvements in the effluent quality from the simulated system were achieved using equalization. The improvements were greater when the influent contained VFAs than when the VFAs were formed by fermentation in the anaerobic zone. The simulations suggested that it may be possible to decrease the amount of phosphorus discharged by a factor as high as 4 through use of concentration equalization. When both flow and concentration equalization were used, the total amount of phosphorus discharged was decreased by a factor of 8. Equalization can be used, in concert with other strategies for preservation of the PHA content of PAOs under periods of low loadings, to minimize the magnitude of Monday phosphate peaks.
Influence of Physicochemical Characteristics of Freshwater on Artificial Radioactivity Content
Authors: Jiménez Antonio , de la Montaña Rufo Ma
Published: September 2006

An intensive study was designed to determine the activity of different radionuclides in water, including strontium‐90 (90Sr), cesium‐134 (134Cs), cesium‐137 (137Cs), plutonium‐239 −240 (239+240Pu), and tritium (3H). Activity levels detected were between 0.6 and 21.3 mBq/L for 90Sr; less than 0.5, 1.4, and 327 Bq/L for 134Cs, 137Cs, and 3H, respectively; and between 0.14 and 21 μBq/L for 239+240Pu. Other nonradioactive parameters were measured including pH; dry residue; conductivity; calcium concentration, [Ca++]; magnesium concentration, [Mg++]; potassium concentration, [K+]; iron(II) and (III) concentration, [Fe2+,3+]; and ammonium concentration [NH4+]. Only the aquifer corresponding to the refrigeration reservoir of the nuclear power plant of Almaraz (Extremadura, Spain) showed greater‐than‐average concentrations of 3H and 239+240Pu compared with those found in the remaining aquifers. The greater presence of dissolved Fe in the waters analyzed clearly indicated greater activity associated with 90Sr, 137Cs, and 239+240Pu in dissolution. In addition, the water samples that were highly mineralized aided the dissolution of 90Sr and (to a lesser extent) 137Cs and made dissolution of 239+240Pu more difficult.
Enhanced Biological Phosphorus Removal in an Anaerobic–Aerobic Sequencing Batch Reactor: Characteristics of Carbon Metabolism
Authors: Jeon Che OK , Lee Dae Sung , Park Jong Moon
Published: September 2006

Carbon metabolism of activated sludge performing enhanced biological phosphorus removal (EBPR) was investigated in a sequencing batch reactor (SBR), where glucose and acetate were supplied as carbon sources. There have been reports that EBPR often failed because of outgrowth of G‐bacteria, which are able to use glycogen (or glucose) alone instead of glycogen and polyphosphate as an internal energy storage pool for the anaerobic uptake and storage of acetate. However, in this experiment, complete EBPR was achieved without proliferation of G‐bacteria despite the supply of glucose in addition to the acetate. Additional one‐cycle SBR operation was carried out to investigate the detailed metabolism of glucose and acetate. Acetate‐using, phosphorus‐accumulating organisms (PAOs) could use glucose as a source for the anaerobic polyhydroxyalkanoate (PHA) synthesis from acetate. However, glucose and acetate were metabolized separately through independent metabolic pathways by respective microorganisms: acetate‐using PAOs, lactate‐producing organisms (LPOs), and lactate‐using PAOs. Glucose was rapidly converted to lactic acid by LPOs before acetate‐using PAOs used the glucose as an energy source for the anaerobic PHA synthesis from acetate and the lactate‐using PAOs anaerobically synthesized PHA from lactate at the expense of polyphosphate. The EBPR was accomplished by acetate‐using PAOs and lactate‐using PAOs independently when glucose acetate were supplied together.
A Comparison of the Fragment Constant and Molecular Connectivity Indices Models for Normalized Sorption Coefficient Estimation
Authors: Tao Shu , Lu Xiaoxia , Cao Jun , Dawson R.
Published: September 2006

Fragment constant and molecular connectivity indices models were developed based on the measured normalized sorption coefficient values of 592 chemicals. The two models were compared for precision in terms of their adjusted coefficients of determination and their mean residuals. Model robustness was evaluated and compared using jackknifed mean residuals derived from class‐by‐class deletion. Results indicated that a relatively greater precision could be achieved using the fragment constant approach compared with the molecular connectivity indices model. The adjusted coefficients of determination of the two models were 0.965 and 0.765 and the mean residuals were 0.366 and 0.440, respectively. Although there were a relatively small number of independent variables involved, the robustness of the molecular connectivity indices model was greater than that of the fragment constant method as far as extrapolation among chemical classes is concerned.
Comparison of Temperature‐Phased and Two‐Phase Anaerobic Co‐Digestion of Primary Sludge and Municipal Solid Waste
Authors: Schmit Kathryn Healy , Ellis Timothy G.
Published: September 2006

Characterization of the similarities and differences between two‐phase and temperature‐phased systems treating primary wastewater sludge (PS) and the organic fraction of municipal solid waste (OFMSW) as substrate was performed by comparing the rates of key steps, including hydrolysis and methanogenesis. Aceticlastic methanogenic rates were determined using batch respirometric tests with inocula from operating two‐phase and temperature‐phased systems. The initial methane production rates ranged from 0.32 to 0.93 mL methane/g volatile solids (VS)·h for all systems, with the greatest rates observed from the first stage of the temperature‐phased system. Hydrolysis rates were determined from particulate chemical oxygen demand destruction. The first stage of the temperature‐phased system had greater specific hydrolysis rates than the first stage of the two‐phase system at each operating condition. The temperature‐phased system outperformed the two‐phase system in terms of methane production and VS destruction when treating a mixed OFMSW–PS stream at OFMSW‐to‐PS ratios of 0:100, 20:80, and 40:60. When the feed ratios were 60:40 and 80:20 OFMSW–PS, there was no significant difference in the performance of the two systems. The overall methane yield and VS destruction of the temperature‐phased system ranged from 0.299 to 0.418 L/g VS fed and 47.5 to 71.6%, respectively. The overall methane yield and VS destruction of the two‐phase system ranged from 0.281 to 0.332 L/g VS fed and 39.6 to 69.3%, respectively.
Removal and Recovery of Chromium(III) from Aqueous Solutions by a Spheroidal Cellulose Adsorbent
Authors: Liu Minghua , Zhang Hong , Zhang Xinshen , Deng Yun , Liu Weiguo , Zhan Huaiyu
Published: September 2006

The removal and recovery of chromium(III) (Cr3+) from aqueous solutions with a spheroidal cellulose adsorbent containing the carboxyl anionic group was investigated. The adsorption of Cr3+ ion on the adsorbent has been found to be time, concentration, pH, and temperature dependent. The adsorption process follows both the Freundlich and Langmuir adsorption isotherms, and has been found to be endothermic (enthalpy change, ΔH = 31.35 kJ/mol). The Cr3+ ion adsorbed on the adsorbent can be recovered by treating with a sodium hydroxide (NaOH) or hydrochloric acid (HCl) solution in one of two methods, static desorption or mobile desorption (column operation). A 1.2 mol/L HCl aqueous solution was finally chosen to recover the Cr3+ ion using column operation. The recovery percentage is approximately 85.2%. The exhausted column can be chemically regenerated by treatment with 1 mol/L NaOH aqueous solution and no dismantling is required. The adsorption mechanism is explained on the basis of complexation and ion exchange, between which the complexation adsorption is predominant.
Quantification of Nitrifying Bacterial Populations in a Full‐Scale Nitrifying Trickling Filter Using Fluorescent In Situ Hybridization
Authors: Biesterfeld Sidney , Figueroa Linda , Hernandez Mark , Russell Philip
Published: September 2006

Fluorescent in situ hybridization (FISH) was used to quantify the ammonia‐oxidizing populations within intact biofilm samples collected from a full‐scale nitrifying trickling filter (NTF). Ammonia, nitrite, and nitrate concentrations were measured for aqueous samples taken in conjunction with biofilm samples at multiple filter depths. Correlation coefficients for individual sampling events, calculated by simple linear regression of FISH signal area and ammonia removal rates, ranged from 0.558 when using probe NEU23a to 0.982 when using probe Nso190. The improved correlations with Nso190 suggest that genera other than Nitrosomonas are present in this system. Percent biofilm coverage, as determined by 4′,6‐diamidino‐2‐phenylindole counterstaining and dry weight biomass measurements, did not change throughout the NTF. This indicates that biofilm growth is fairly uniform throughout the filter even if nitrifier growth is not.
Performance Evaluation of a Marshland Upwelling System for the Removal of Fecal Coliform Bacteria from Domestic Wastewater
Authors: Watson Robert E. , Rusch Kelly A.
Published: September 2006

The Marshland Upwelling System (MUS), a potential alternative wastewater treatment strategy for coastal dwellings, was examined to assess its ability to remove fecal coliforms (FC) from domestic wastewater as a step towards total treatment. Wastewater was intermittently injected down a 4.6‐m injection well into the surrounding salt marsh. Optimal performance was achieved at an injection flowrate of 1.9 L/min and injection frequency of 30 minutes every 3 hours. Average influent concentrations of 930 000 ± 650 000 colonies/100 mL were reduced to effluent counts of 4.6 colonies/100 mL. Coliform removal followed exponential decay versus vector distance traveled with predicted surface concentrations less than or equal to 0.1 colony/100 mL. Hydraulic performance was acceptable with no significant reductions in permeability observed. Increasing flows to 3.8 L/min produced localized hydraulic dysfunction as indicated by sudden increases in effluent bacterial counts and injection pressures. Although fecal coliform removal typically decreased with increasing injection flowrates and isolated instances of abnormally high effluent counts were observed the MUS never experienced a catastrophic failure during the 13‐month evaluation period.
Determination of Optimal Peat Type to Potentially Capture Copper and Cadmium from Solution
Authors: Brown Pauline , Gill Sarah , Allen Stephen J.
Published: September 2006

The focus of this study was to determine the optimum type of peat for application as a medium to capture dissolved metals from aqueous solution. Seventeen media were examined, including eleven Irish peat samples from various locations and stages in processing, a Northern Ireland lignite, peat and lignite chars, a commercial‐grade bone char, and two commercial‐grade granular activated carbons. Considerable variation in sorption capacity was found with a ratio of 20:1 between the best‐performing (bone char) and the poorest‐performing (peat char) samples. Among the 14 varieties of peat, the best‐performing sample outperformed the commonly investigated sphagnum moss by a ratio of 4:1. A correlation has been established between cation exchange capacity, the presence of adsorbed calcium, and the uptake capacity of different peats. This correlation will be a valuable tool in choosing peat type for filter media for metals removal applications.
Wastewater Dewatering Polymer Affect on Biosolids Odor Emissions and Microbial Activity
Authors: Rosenfeld Paul E. , Henry Charles L. , Bennett Daniel
Published: September 2006

Odor emissions and microbial activity associated with biosolids dewatered using seven different polyacrylamide cationic polymers were investigated. Nitrogen, sulfur, ketone, and odor unit emissions, and biosolids microbial community metabolic profiles were measured for biosolids containing each polymer. Ammonia represented more than 98% of total nitrogen flux for all polymers, with small concentrations of trimethyl amine. Dimethyl disulfide and carbon disulfide fluxes summed represented 87 to 97% of the sulfur flux for all polymers, with lesser quantities of dimethyl sulfide. Maximum dimethyl disulfide, ammonia, and trimethyl amine concentrations were estimated to be 3.4, 3.2, and 13.5 times greater than published detection limits, respectively. Maximum dimethyl sulfide, carbon disulfide, acetone, and methyl ethyl ketone concentrations were estimated to be 0.028, 0.007, 0.002, and 0.000 6 times less than published detection limits, respectively. All treatments were found to volatilize equal odor unit emissions (with the exception of one polymer), and polymers were not found to dramatically affect odor emission from biosolids application. Metabolic fingerprints revealed differences in the ability of microbial communities from certain polymer treatments to degrade amino acids as a sole carbon substrate. In addition, odor unit emissions were significantly correlated with potential for amino acid decomposition.
Stratification and Oxidation–Reduction Potential Change in an Aerobic and Sulfate‐Reducing Biofilm Studied Using Microelectrodes
Authors: Yu Tong , Bishop Paul L.
Published: September 2006

Recent studies in aerobic–nitrifying biofilms demonstrated the heterogeneity of biofilms used in wastewater treatment and led to modifications of the homogeneous assumptions in the conventional biofilm kinetic models. However, the stratification in aerobic–anaerobic biofilms has not been well investigated because of a lack of effective experimental tools. In this study a suite of microelectrodes, recently developed in the authors' laboratory, was used to examine the stratification of microbial processes and the change of oxidation–reduction potential (ORP) within an aerobic, sulfate‐reducing biofilm. The microelectrodes have tip diameters of 3 to 20 μm and a high spatial resolution. They were used to measure the profiles of oxygen, total dissolved sulfide, ORP, and pH as a function of depth in the biofilm. The biofilm reactor was used to treat an azo‐dye‐containing wastewater with a chemical oxygen demand of 160 mg/L. The reactor bulk‐phase dissolved oxygen concentration of the biofilm was 1.7 mg/L. The experimental results demonstrated that the microbial processes in the biofilm were stratified. In this biofilm, aerobic oxidation took place only in a shallow layer of 0.55 mm near the surface and sulfate reduction occurred in the deeper anoxic zone. The ORP changed with the shift of primary microbial process. The ORP was + 362 mV at the biofilm surface and −166 mV near the substratum. Near the interface between the aerobic zone and the sulfate reduction zone, a surprisingly sharp decrease of ORP from a positive potential of 1 194 mV to a negative potential of 2 77 mV was observed. This occurred within a narrow band of 50 μm in depth. These new experimental findings support the concept of stratification of microbial processes and the associated ORP change in biofilms.
Enhanced Biological Phosphorus Removal in an Anaerobic–Aerobic Sequencing Batch Reactor: Effect of pH
Authors: Jeon Che OK , Lee Dae Sung , Lee Min Woo , Park Jong Moon
Published: September 2006

Enhanced biological phosphorus removal (EBPR) is not always successfully achieved in activated‐sludge processes by anaerobic–aerobic operation. It has been reported that the deterioration of EBPR has been caused by domination of glycogen‐accumulating organisms (GAOs) in microbial sludge. After repeated operation of a sequencing batch reactor (SBR) supplied with acetate as a sole carbon source, it was found that an operational variable, pH, could be a tool to control the competition between GAOs and polyphosphate‐accumulating organisms PAOs, which could mediate the success of EBPR. When anaerobic phase pH in the SBR was controlled at 7.0, GAOs dominated the culture, resulting in failure of EBPR. Without pH control, the pH during the anaerobic phase increased to 8.4 as a result of denitrification and acetate uptake. In this relatively high pH condition, almost complete EBPR was achieved. In this report, the mechanism of pH effect on the competition between GAOs and PAOs was elucidated through a characterization of activated sludge using previously proposed biochemical models.
A Biological Phosphorus Removal Potential Test for Wastewaters
Authors: Park J.K. , Whang L.M. , Wang J.C. , Novotny G.
Published: September 2006

A simple test was proposed to assess whether phosphorus in a wastewater can be removed using a biological phosphorus removal (BPR) process. The test includes the measurement of phosphorus release during 2 hours of the anaerobic stage in a batch reactor containing phosphorus‐accumulating organisms (PAOs) and estimation of the effluent phosphorus concentration using biochemical relationships. The BPR potential test developed allowed for the successful evaluation of BPR feasibility for five wastewater samples. The BPR potential test was validated by comparing the test results with the effluent phosphorus concentrations measured in a sequencing batch reactor (SBR). An effluent phosphorus concentration of 1.9 mg P/L predicted for the BPR potential test performed was close to the effluent phosphorus concentration of 1.8 mg P/L obtained from an SBR on the same day. During the anaerobic stage, phosphorus release was significantly affected by the sludge concentration initially, but became insignificant after 2 hours. The initial sludge concentration affected the phosphorus release rate; thus, it is recommended that the BPR potential test be conducted at a target mixed liquor volatile suspended solids concentration. It is also recommended that the BPR potential test be conducted at the site where the PAO‐containing sludge is available and the wastewater sample can be delivered at 4 °C in less than 24 hours. The PAOs in different sludges had almost identical phosphorus release after 2 hours; however, the characteristics of facultative bacteria in sludges affected the phosphorus release. If the wastewater is prefermented for at least 3 days before the BPR potential test, the amount of phosphorus released by various PAO‐containing sludges is expected to be identical.
Activated Carbon and Wood Ash Sorption of Wastewater, Compost, and Biosolids Odorants
Authors: Rosenfeld Paul E. , Henry Charles L.
Published: September 2006

Odor emissions from wastewater treatment facilities and composting operations and land application of biosolids are priority concerns for wastewater engineers, compost operators, and biosolids managers. High carbon wood ash is a material produced by the pulp and paper industry and cogeneration energy producing facilities; although this material has been found to have characteristics similar to activated carbon, it is currently treated as waste and deposited in landfills. To control odors associated with wastewater and biosolids, activated carbon and wood ash were exposed to odorants that often are associated with biosolids and wastewater, including dimethyl disulfide, dimethyl sulfide, carbon disulfide, ammonia, trimethyl amine, acetone, and methyl ethyl ketone. The sorption materials included activated carbon containing 87% carbon and wood ash residuals containing 32, 27, 6, and 0.24% carbon, with surface areas of 520, 85, 74, 25, and 2.1 m2/g, respectively. This laboratory sorption experiment was undertaken to examine sorption efficiency and kinetics of chemical odorants by activated carbon and wood ash residuals. Results demonstrate that wood ash with higher carbon concentrations and higher surface areas sorbed odorants better than low‐carbon ash. Furthermore, the 32 and 27% carbon wood ash possessed characteristics similar to activated carbon and were able to sorb odorous gases effectively.
Treatment of High‐Strength Winery Wastewater Using a Subsurface‐Flow Constructed Wetland
Authors: Shepherd Heather L. , Grismer Mark E. , Tchobanoglous George
Published: September 2006

Rapid expansion of the wine industry in rural California during the past three decades has created environmental contamination problems related to winery wastewater treatment and disposal. Often, winery wastewater is stored and treated in aerated ponds and disposed via postharvest vineyard irrigation; however, little research has been conducted on on‐site treatment and its potential for downstream contamination. Throughout a given year, winery wastewater is extremely variable in quality and discharge volume. In addition to characterizing the wastewater, this study investigates the performance of a pilot‐scale subsurface‐flow constructed wetland (6.1‐m long by 2.4‐m wide by 1.2‐m deep) in treating winery wastewater from a moderate‐sized winery (2 million cases/a). Winery wastewater flowrates ranged from 80 to 170 m 3/d at organic loads of 600 to 45 000 mg chemical oxygen demand (COD)/L. The study measured average removal rates of 98% for COD and 97% for total suspended solids using the subsurface‐flow constructed wetland combined with an upflowing sand prefilter loaded at variable rates as great as 1640 kg COD/ha z d, or 8 times the recommended value. The system also seemed to be effective at neutralizing pH of the high‐strength, acidic winery wastewater and at removing the limited nitrogen (78.2%) in the wastewater, in addition to sulfide (98.5%), ortho‐phosphate (63.3%), volatile fatty acids (99.9%), phenols (100%), tannins and lignins (77.9%), and settleable solids.
Treatment of Septage Using an Upflow Anaerobic Sludge Blanket Reactor
Authors: Lin Chiu‐Yue , Chang Feng‐Yun , Chang Chun‐Hao
Published: September 2006

This study examined the feasibility of applying an upflow anaerobic sludge blanket (UASB) reactor to treat septage. The UASB reactor was operated at 35 ± 1 °C, and the substrate septage had a total solids (TS) concentration of 13 200 mg/L. Reactor operation was initiated at a hydraulic residence time (HRT) of 10 days; thereafter, the HRT was shortened stepwise to 1.5 days. The TS, volatile solids (VS), and organic loading rates were 1.4 to 9.4 kg TS/m3·d, 5.6 to 8.5 kg VS/m3·d, and 1.1 to 6.7 kg chemical oxygen demand (COD)/m3·d, respectively. At the organic loading rate of 6.7 kg COD/m3·d (the HRT of 1.5 days), the total COD, soluble COD, and TS and VS removal efficiencies were 68, 74, and 66 and 73%, respectively. The average granule diameter and volatile suspended solids concentration were approximately 0.89 mm and 32 000 mg/L, respectively. Based on results obtained from 7 months of constant methane production and removal efficiencies, which are comparable to values previously reported in the literature for wastewater, it was concluded that a UASB reactor can successfully treat septage.
The Effect of the Ammonium Ion on Activated‐Sludge Settling Properties
Authors: Novak John T.
Published: September 2006

High levels of sodium in wastewater have been found to be detrimental to activated‐sludge settling and dewatering. Another potentially troublesome monovalent cation in activated‐sludge systems is the ammonium ion. This study was conducted to determine if the ammonium ion could alter activated‐sludge settling and dewatering properties. Side‐by‐side laboratory activated‐sludge reactors were fed equal concentrations of an organic substrate (bactopeptone), and the same divalent cations were provided in the feed. However, the monovalent cations were varied either by inhibiting nitrification so that the ammonium concentration would increase or by adding sodium. These studies showed that an increase in either sodium or ammonium would cause activated‐sludge settling properties to deteriorate. When the monovalent‐to‐divalent cation ratio on a charge‐equivalent basis was increased from 2.4 to 4.7 either by addition of sodium or ammonium, the interfacial settling velocity decreased, although the greatest drop was in the reactor containing ammonium. When addition of the nitrification inhibitor was stopped, rapid recovery of nitrification occurred but the settling properties improved more slowly. It seemed that recovery was due to replacement of the activated sludge with new flocs rather than alteration of the existing biomass.
Control of External Carbon Addition in Biological Nitrogen Removal Process for the Treatment of Coke‐Plant Wastewater
Authors: Lee Min Woo , Park Yun Jung , Park Jong Moon , Chun Hee Dong
Published: September 2006

An online monitoring and controlling system was developed for controlling external carbon addition in the biological nitrogen removal (BNR) process of a coke‐plant wastewater treatment plant. Two control regimes, on–off control and feed‐forward control, were applied and their performances were compared under normal and abnormal nitrate (NO−3–N) input conditions. The water quality of the final effluent was stably controlled under normal nitrate input conditions by using the on–off control algorithm that is connected to the effluent nitrate concentration. However, unexpected nitrite accumulation was observed under abnormal nitrate input conditions (i.e., sudden increase of nitrate concentration), resulting from chemical oxygen demand (COD) limitations during denitrification. On the contrary, the feed‐forward control algorithm more reliably controlled external carbon addition even under abnormal nitrate input conditions. The input COD/NO−3–N was controlled between 3.55 and 3.62 during the operational period when the feed‐forward algorithm was applied. Through trial and error, the optimum value of COD/NO−3–N for denitrification was determined to be 3.59 in separate experiments.
Treatment of Mixed Hydrogen Sulfide and Organic Vapors in a Rock Medium Biofilter
Authors: Chitwood Derek E. , Devinny Joseph S.
Published: September 2006

A pilot‐scale biofilter was operated at a publicly owned treatment works to remove hydrogen sulfide and a mixture of volatile organic compounds (VOCs) from waste gas streams. Lava rock was used for the medium, which averaged pH 4 during the study. The study itself was conducted in three phases. The bed volume was 9.8, 6.5, and 3.3 m3 in phases 1, 2, and 3, respectively, while the flowrate was approximately 17 m3/min throughout the study. The removal efficiency of hydrogen sulfide was consistently greater than 90% for all three phases and, despite low‐pH conditions, weighted average VOC removal was greater than 70%. The lava rock provided a hospitable environment for microorganisms while causing low head loss (25 Pa at a load rate of 3.8 m/min). However, lava rock is susceptible to dissolution at low‐pH conditions (the degree of dissolution depends on the source of the material).