bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial indicator reductions in alternative treatment systems for swine wastewater
Authors: Hill V. R. , Sobsey M. D.
Published: May 2018

Bacterial, viral and parasitic pathogens in swine wastes are of public health concern because many are able to infect humans. Hence, treatment processes must be effective in removing or destroying these microbes before wastewater discharge. Primary treatment by anaerobic lagoon is the current best management practice (BMP) for swine wastewater in the USA but alternative processes were also investigated for their potential to improve treatment. Wastewater samples were collected approximately monthly from March-December 1997 at a North Carolina swine nursery. Geometric mean concentrations for bacterial indicators (faecal coliforms, E coli, enterococci and C perfringens spores) in lagoon effluent were 3.3×105, 2.8×105, 3.4×105 and 2.2×104 CFU/100mL respectively. For somatic and male-specific coliphages they were 1.4×105 and 5.0×103 PFU/100mL respectively. Bacterial indicator levels in swine lagoon effluents are much higher than allowed for municipal wastewater effluents discharged to land or water. The anaerobic lagoon achieved reductions of 1.1–2.2 log10 for all indicators except C perfringens spores (0.2 log10). Of the secondary treatment processes, constructed wetlands achieved the best indicator microbe reductions ranging from 1.1–2.5 log10. A media filter and an overland flow system achieved mean indicator reductions of only 0.2–1.2 and 0.2–0.8 log10, respectively. The results indicate that a primary-secondary treatment system, an anaerobic lagoon and constructed wetlands, can achieve reductions of 2.9–4.8 log10 for bacterial and viral indicators and 1.5 log10 for C perfringens spores.
The effect of fatty acid alteration in coliform bacteria on disinfection resistance and/or adaptation
Authors: Abu-Shkara F. , Neeman I. , Sheinman R. , Armon R.
Published: May 2018

Natural waters are treated by various chemical and physical processes to improve their quality and to prevent disease spread. Among the last stages of water treatment is disinfection (the only treatment in Israel). This process is carried out by application of chlorine, chloramine or chlorine dioxide in order to inactivate bacteria, viruses and other single cell organisms found in water systems. Survival of some of these bacteria or microorganisms following disinfection is still a serious problem. Bacteria were isolated from disinfected water with residual free chlorine of nearly 1mg/L. The present study analysed the composition of cellular fatty acids of coliform bacteria such as Klebsiella oxytoca, Escherichia coli, Citrobacter freundii and Enterobacter taylorae exposed to different environmental conditions, including disinfection, and the effect of biochemical changes on their survival potential. Nutrition (high and low), temperature (6°C and 35°C) and aggregation (0.45–8μm sized aggregates) were tested with selected coliforms for their impact on chlorine resistance and cellular fatty acids alteration. Nutrition effect on the fatty acid composition of these bacteria showed a variable pattern with each bacterial strain; nevertheless bacteria grown in diluted medium displayed higher resistance to chlorine. Whilst temperature effect results showed that bacteria grown at lower temperatures are more resistant to chlorination, fatty acids analysis failed to reveal a constant pattern and variability was found among the bacterial strains tested. Bacterial species that formed aggregates in the water environment were more resistant to chlorine. The results of this study indicate that several processes are involved in bacterial resistance/adaptation to chlorine stress and together they form a barrier against external damages caused by chemical disinfection. The implication of these results on future disinfection practices is discussed.
Reduction of Norwalk virus, poliovirus 1 and coliphage MS2 by monochloramine disinfection of water
Authors: Shin G.-A. , Sobsey M. D.
Published: May 2018

The reduction of Norwalk virus (NV) by a 2 mg/L dose of pre-formed monochloramine was determined at pH 8 and 5°C in bench-scale, batch disinfection experiments using quantitative RT-PCR for NV assays. Two other enteric viruses, poliovirus 1 (PV1) and coliphage MS2, were included for comparison and assayed by infectivity as well as RT-PCR. After 3h, reductions of PV1 and MS2 by infectivity assays were about 1 log10 but there were no reductions of these viruses by RT-PCR assays. Hence, RT-PCR underestimated virus inactivation by monochloramine. However, NV reduction by monochloramine was about 1 log10 by RT-PCR assay, suggesting that it is more susceptible to monochloramine than the other two viruses tested. Based on RT-PCR titre reduction, the CT99 value for NV was about 775 mg-min/L. If the reduction of NV infectivity by monochloramine is ever greater than the reduction of RT-PCR signals, the CT99 value would be smaller. However, the results of this study indicate that NV and the other enteric viruses tested are not rapidly and extensively reduced by disinfection with pre-formed monochloramine.
pH-controlled reject-water-treatment
Authors: Wett B. , Rostek R. , Rauch W. , Ingerle K.
Published: May 2018

Dewatering of digested sludge causes significant internal nitrogen loading to a wastewater treatment plant. Due to the high concentration of nitrogen it is more effective to treat the reject-water not directly in the main purification process but to apply a separate biological treatment procedure. The intermittent operation of sludge-press facilities, the high initial pH-value of reject-water and the quick loss of alkalinity during nitrification makes a reliable control of the process necessary. A sequencing batch reactor (SBR) with an operational control based on on-line measurement of the pH-value is well suited to meet this requirement. Such a control system for discontinuous treatment of reject-water has been extensively tested and optimised in full-scale experiments since 1995. The closed loop control of the pH-value was developed to keep the bicarbonate concentration within an optimum range. At the WWTP Strass in western Austria stable nitrification rates of 50 to 60 mg NH4-N/l/h have been achieved (elimination of 200 kg nitrogen per day).
Simulation and system identification of dynamic models for flocculation control
Authors: Wistrom Anders , Farrell Jay
Published: May 2018

Instrumentation to support advances in particle-fluid separation control have recently become commercially available; however process models, system identification and automatic control laws are still required. This article first describes the derivation and simulation of a dynamic model for the flocculation process based on a population balance approach. This process model contains a poorly modeled function of the coagulant, mixing power, and average particle size. Accurate on-line identification of this function will be critical for the implementation of high performance flocculation control. As an initial step in this direction, this article describes experimental work involving identification of this unknown function across independent controlled experiments. Consistent results partially validate the proposed system model. The ultimate objective is to use detailed particle size distribution measurements and the dynamic models of particle flocculation to analyze and develop control laws for the flocculation process.
Comparative adsorption of norwalk virus, poliovirus 1 and F+ RNA coliphage MS2 to soils suspended in treated wastewater
Authors: Meschke J. S. , Sobsey M. D.
Published: May 2018

Enteric viruses such as Norwalk virus (NV) are important agents of waterborne disease from faecally contaminated groundwater. Viruses are more resistant to inactivation than most enteric bacteria and they may not be removed efficiently during land application. Adsorption is one of the major factors in viral removal and persistence in soils. The adsorption of NV by soils suspended in wastewater has not been determined. Therefore, we determined the adsorption of NV to six soils (Cecil clay-loam, Corolla sand, Georgia Kaolinite (clay), Wyoming Bentonite (clay), Ponzer organic muck and Flushing Meadows sand-loam) suspended in treated wastewater and compared it to that of poliovirus 1 (PV1) (strongly adsorbed) and MS2 (weakly adsorbed). NV is shown to be less sorptive than PV1 and more sorptive than MS2. Furthermore, relative virus adsorption among soils was similar for all three enteric viruses with viruses most adsorbed by clays and least adsorbed by sand and organic soils.
Analysis of endogenous process behaviour
Authors: Keesman K. J. , Spanjers H. , van Straten G.
Published: May 2018

In this paper an autonomous four-compartment model that describes the endogenous respiration in a aerobe biodegradation process is proposed and analysed theoretically. First the multi-time scale of the system's behaviour, to be taken into account in subsequent analyses, is emphasized. Then, an identifiability study, given measurements of MLVSS (mixed liquor volatile suspended solids) and respiration rate, is performed for use under practical circumstances such as in parameter estimation. It appears that the process is not fully identifiable. Hence, for the identification of some of the model parameters additional measurements or experiments, also indicated in the paper, have to be performed. Furthermore, it is shown that, under quasi-steady state conditions which in general appear shortly after initialization of an endogenous respiration experiment, the model can be reduced significantly.
Theoretical and practical identifiability of a reduced order model in an activated sludge process doing nitrification and denitrification
Authors: Julien S. , Babary J. P. , Lessard P.
Published: May 2018

This paper deals with the structural identifiability and the identification of the parameters of a reduced order model used for control of a single reactor activated sludge process doing nitrification and denitrification. This reduced order model is splitted into two submodels, one 3-dimensional state submodel in aerobic conditions and one 2-dimensional state submodel in anoxic conditions. The identifiability analysis is based on on-line oxygen and nitrate concentrations data. It has been shown that the reduced order model is structurally identifiable. The parameter identification has been carried out by using the simplex method of Nelder and Mead. Simulation results performed over a range of six hours (two aerobic/anoxic cycles), show that there exists a good fit between the simulated solution and the actual behavior of a lab scale pilot plant.
A comparison between model and rule based control of a periodic activated sludge process
Authors: Isaacs S. , Thornberg D.
Published: May 2018

Two strategies for control of nitrogen removal in an alternating activated sludge plant are compared. One is based on simple model predictions determining the cycle length at the beginning of each cycle. The other is based on simple rules relating present ammonia and nitrate concentrations. Both strategies are close in efficiency measured as effluent total (inorganic) nitrogen and both perform better than using fixed phase lengths for a test scenario describing a typical dry weather diurnal variation. After modifying the criterion functions of the rule based strategy the two strategies are found to produce equivalent controls, which means that the optimal criteria of the model based strategy can be fulfilled without the need for model predictions.
Prediction of hydraulic load for urban storm control of a municipal WWT plant
Authors: Carstensen Jacob , Nielsen Marinus K. , Strandbæk Helle
Published: May 2018

Three different methodologies are assessed which provide predictions of the hydraulic load to the treatment plant one hour ahead. The three models represent three different levels of complexity ranging from a simple regression model over an adaptive grey-box model to a complex hydrological and full dynamical wave model. The simple regression model is estimated as a transfer function model of rainfall intensity to influent flow. It also provides a model for the base flow. The grey-box model is a state space model which incorporates adaptation to the dry weather flow as well as the rainfall runoff. The full dynamical flow model is a distributed deterministic model with many parameters, which has been calibrated based on extensive measurement campaigns in the sewer system. The three models are compared by the ability to predict the hydraulic load one hour ahead. Five rain events in a test period are used for evaluating the three different methods. The predictions are compared to the actual measured flow at the plant one hour later. The results show that the simple regression model and the adaptive grey-box model which are identified and estimated on measured data perform significantly better than the hydrological and full dynamical flow model which is not identifiable and needs calibration by hand. For frontal rains no significant difference in the prediction performance between the simple regression model and the adaptive grey-box model is observed. This is due to a rather uniform distribution of frontal rains. A single convective rain justifies the adaptivity of the grey-box model for non-uniformly distributed rain, i.e. the predictions of the grey-box model were significantly better than the predictions of the simple regression model for this rain event. In general, models for model-based predictive control should be kept simple and identifiable from measured data.
Distribution reservoir control with demand prediction using deterministic-chaos method
Authors: Oshima N. , Kosuda T.
Published: May 2018

Besides serving the water needs of the community, the distribution reservoir has two particular functions to perform; to adjust reservoir discharges according to time-related variation in demand and to have a reserve to handle emergencies. If priority is given to the former function, then its water level varies; if reserve function is a primary consideration, then the reservoir water level remains stably high. In actual reservoir operation it is important to maintain an adequate balance between the two functions. Demand forecasting seems helpful in meeting this need. Since the storage capacity of distribution reservoirs is no greater than several to 10-odd hours in terms of discharging time, shorter demand forecasts than before should desirably be made in hour units. We developed a method for making hourly forecasts of water demand, using the theory of chaos control and evaluated its usefulness in solving distribution reservoir problems through simulation. The future water level of a reservoir was predicted based on the data obtained by demand forecasting and water pumps were operated to keep the reservoir water level in the goal range. As a result, an adequate balance could be maintained between the two reservoir functions so that the frequency of pump operation could be reduced to improve energy efficiency.
The hunt for the G-bacteria in activated sludge biomass
Authors: Maszenan A. M. , Seviour R. J. , Patel B. K. C. , Rees G. N. , McDougall B.
Published: May 2018

Routine microscopic examination of biomass samples from many activated sludge plants around the world reveals the presence of large numbers of both Gram positive and Gram negative coccoid cells often arranged in distinctive tetrads or sheets of tetrads. Three Gram negative tetrad cocci were successfully isolated into pure culture using micromanipulation from samples of biomass from plants in Tamworth, N.S.W., Australia, Verona, Italy and Macau. After extensive phenotypic characterisation and 16S rDNA sequence analysis, all isolates showed high overall similarity to each other, but were phylogenetically quite different to any previously sequenced bacterium. They have therefore been classified as three species of a new genus, the genus Amaricoccus in the α Proteobacteria in the domain Bacteria. None could accumulate polyphosphate granules, and production of intracellular poly-β-hydroxybutyrate (PHB) granules depended on the carbon source used in the medium. A similar characterisation of the original isolate of the G-bacteria described by Cech and Hartman showed this organism also belonged to the same genus as the other three isolates, but as a distinct species. The practical implications of these observations are discussed.
The comparison of the diversity of activated sludge plants
Authors: Curtis Thomas P. , Craine Noel G.
Published: May 2018

The explicit engineering of bacterial populations requires that we know which organisms perform which tasks. The comparison of the bacterial diversity of activated sludge plants may give important information about the functions of different bacteria. This difficult task may be made easier by the use of technologies based on 16S rRNA based techniques. In this study we have used denaturing gradient gel electrophoresis (DGGE) to determine the optimal sampling regime for comparative studies and used cluster analysis to show how plants may be quantitatively compared. We sought evidence of spatial, diurnal and intrasample variation in a number of sites. No evidence for variation was found in the plants studied and we concluded that a single sample of an activated sludge plant was sufficient for a plant to plant comparison. The cluster analysis was able to distinguish between plants, though further work is required to find the most appropriate basis for such comparisons. We found organisms from raw sewage in the mixed liquor samples, these organisms may have no functional significance in the treatment process and thus complicate plant to plant comparisons as will the probable presence of heteroduplex rDNA products. Nevertheless we believe that these drawbacks do not outweigh the advantages of being able to take and compare relatively large numbers of samples.
Heterotrophic active biomass component of activated sludge mixed liquor
Authors: Wentzel M. C. , Ubisi M. F. , Ekama G. A.
Published: May 2018

In the current steady state design and kinetic simulation models for activated sludge systems, the heterotrophic active biomass (XH) is a key parameter. However, this parameter remains hypothetical within the structure of the models; it has not been measured directly, primarily due to the lack of suitable simple experimental techniques. In this paper a simple batch test procedure is used to quantify XH in mixed liquor samples drawn from a well-defined parent anoxic/aerobic activated sludge system operated at sludge ages 12d and 20d. The measured XH concentrations are in close agreement with those calculated theoretically for the parent system at 12d sludge age, but are about 1/2 the theoretical values for the system at 20d sludge age. While the good correspondence at 12d sludge age provides substantive direct evidence supporting both the models and the experimental method, reasons for the poor correspondence at 20d sludge age need to be found.
Laboratory scale inactivation of pig viruses in pig slurry and design of a pilot plant for thermal inactivation
Authors: Turner Claire , Williams Stuart M. , Burton Colin H. , Farrent John W. , Wilkinson Philip J.
Published: May 2018

African swine fever (ASF) and swine vesicular disease (SVD) are virus diseases that threaten the pig populations in Europe. This paper examines the effectiveness of two methods used to inactivate these two viruses in pig slurry, and then describes the design of a pilot plant which makes use of one inactivation method. The first method is the addition of alkali, specifically NaOH or Ca(OH)2 at various concentrations. ASF virus (ASFV) required 1% of either NaOH or Ca(OH)2 for inactivation; SVD virus (SVDV) required 1.5% NaOH or Ca(OH)2 for similar inactivation. The second method was the application of heat. ASFV was inactivated to below detectable levels at 56°C within 90 seconds, whereas SVDV required 60°C for inactivation within 90 seconds. Heat was identified as the most suitable method, and a pilot plant was designed and assembled for the inactivation of viruses in pig slurry at a rate of up to 100 litres per hour.
Characteristics of adsorption of rice-hull activated carbon
Authors: Kim K. S. , Choi H. C.
Published: May 2018

An experiment was conducted to compare the adsorption capacity and characteristics between activated carbon made of rice-hull(RHAC) and F-400 by Calgon to remove phenol, heavy metal and ammonia-nitrogen. While F-400 could not remove ammonia-nitrogen, RHAC was able to adsorb it. This is considered to be due to the ionic sorption capability of SiO2 remaining on the surface of RHAC. From the sorption equilibrium test, it was found that RHAC has higher adsorption capacity than F-400. In column tests, the slope of breakthrough curves of RHAC which represent the affinity of an adsorbent, was observed to be more gradual than F-400. This may be attributed to the inner diffusion of adsorbent once attached on macropores, into micropores well developed, with higher specific surface area of RHAC than F-400. For heavy metals, F-400 would remove chromium and lead but not cadmium, whereas RHAC was able to remove cadmium, lead but not chromium. This phenomenon is considered to have something to do with the distinct surface functional group of RHAC and the various surface charge densities of heavy metals tested.
A new oxygen supply method for simultaneous organic carbon removal and nitrification by a one-stage biofilm process
Authors: Yamagiwa Kazuaki , Yoshida Masanori , Ito Akira , Ohkawa Akira
Published: May 2018

A new oxygen supply method to biofilm is proposed for simultaneous organic carbon removal and nitrification. The main feature of the method is use of hydrophobic porous membrane or oxygen enrichment membrane as substratum of biofilm. In the biofilm formed on oxygen permeable membrane, oxygen is supplied from the bottom to the surface of the biofilm through the membrane while organic pollutants are supplied from the surface to the bottom of the biofilm. The oxygen supply method allows nitrifiers near the bottom region to grow with less competition from BOD oxidizers. The microbial population was investigated in the biofilm formed on hydrophobic microfilter. Nitrifiers grew mainly in the bottom region while denitrifiers grew in the middle region of the biofilm formed on the membrane. Simultaneous organic carbon removal and nitrification were carried out successfully by the biofilm. Furthermore, the potential of the new oxygen supply method was demonstrated with the biofilm formed on an oxygen enrichment-type biomass carrier in a single-stage treatment of domestic wastewater. The nitrification rate was about 1.9 g/m2d and was comparable to that in the conventional biofilm process designed especially for nitrification.
Integrated environmental risk assessment for petroleum-contaminated sites - a North American case study
Authors: Chen Z. , Huang G. H. , Chakma A.
Published: May 2018

Development of petroleum industries is associated with a number of environmental concerns. Among them, soil and groundwater contamination by petroleum products is of major concern. In this study, an integrated risk assessment approach is proposed for evaluating environmental risks derived from petroleum-contaminated sites. The proposed approach is composed of (i) a hydrocarbon spill screening model (HSSM) which is used for simulating immisicible flow of released hydrocarbons in vadose zone, formation of lens in capillary fringe, dissolution of pollutants at water table, and transport of the pollutants to receptors, and (ii) a fuzzy relation analysis (FRA) model which is developed for comprehensively evaluating risks caused by a number of pollutants with different impact characteristics, based on the HSSM results. This hybrid HSSM-FPA approach was applied to a case study for a petroleum-contaminated site in western Canada, where soil and groundwater was contaminated by industrial wastes containing benzene, toluene, ethylbenzene and xylenes (BTEXs). The results suggest that the HSSM-FRA can provide insight into the potential risk to the receptor of concern downward the acquifer and can serve as a basis for further remediation-related decision analysis.
A new treatment process for photo-processing waste using a sulfur-oxidizing bacteria/granular activated carbon system followed by Fenton oxidation
Authors: Lin Binle , Yamaguchi R. , Hosomi M. , Murakami A.
Published: May 2018

Establishing a treatment process for practical, economic disposal of photo-processing waste (PW) has become an urgent environmental concern under recently enacted provisions of the London Treaty. This paper describes a new, effective biological/chemical treatment process in which sulfur-oxidizing bacteria (SOB) is used in conjunction with granular activated carbon (GAC), i.e., an aerobic SOB/GAC system, to treat PW prior to Fenton oxidation. Weak dilution PW was treated in a long-term (98 d) continuous treatment such that mass-reduced sulfur compounds were completely oxidized to sulfate, while biodegradable organics in dissolved organic carbon (DOC) were simultaneously degraded at a removal rate of 55%. The remaining refractory/toxic compounds following aerobic SOB/GAC treatment were then effectively transformed to biodegradable organics without pH regulation by adding only 123-154 ml of 30% H2O2, whereas without aerobic SOB/GAC treatment, 670 ml (12% H2O2) was required. Under this innovative approach, DOC in PW was effectively degraded at a removal rate of about 95%, with the required amount of H2O2 being reduced by 77% and the occurrence of sudden boiling being completely removed.
Influence of dissolved oxygen on nitrification kinetics in a circulating bed reactor
Authors: Lazarova V. , Nogueira R. , Manem J. , Melo L.
Published: May 2018

The influence of dissolved oxygen concentration in nitrification kinetics was studied in a new biofilm reactor, the circulating bed reactor (CBR). The study was carried out partly at laboratory scale with synthetic water containing inorganic carbon and nitrogen compounds, and partly at pilot scale for secondary and tertiary nitrification of municipal wastewater.

The experimental results showed that either the ammonia or the oxygen concentration could be limiting for the nitrification rate. The transition from ammonia to oxygen limiting conditions occurred for an oxygen to ammonia concentration ratio of about 1.5 - 2 gO2/gN-NH4+ for both laboratory- and pilot-scale reactors. The nitrification kinetics of the laboratory-scale reactor was close to a half order function of the oxygen concentration, when oxygen was the rate limiting substrate.
Integration of performance, molecular biology and modeling to describe the activated sludge process
Authors: Urbain V. , Mobarry B. , de Silva V. , Stahl D. A. , Rittmann B. E. , Manem J.
Published: May 2018

To study process performance and population dynamics in activated sludge, a pilot-scale Membrane Bioreactor (MBR) was installed in a municipal wastewater treatment plant (Aubergenville, France). Since no solids losses occur in the MBR effluent, the sludge residence time (SRT) can be: i) easily controlled by means of the sludge withdrawal, and ii) dissociated from the hydraulic residence time (HRT). A complete characterization of this activated sludge system was performed at three sludge ages (5, 10 and 20 days). Raw and treated wastewater quality, as well as sludge concentration, was analyzed, nucleic probe analysis was performed to determine the heterotrophic and nitrifier populations, and the results were compared to the output from a multispecies model that integrates substrate removal kinetics and soluble microbial products (SMP) production/consumption. This paper presents an integrated analysis of the activated sludge process based on chemical, molecular biology, and mathematical tools. The model was able to describe the MBR system with a high degree of accuracy, in terms of COD removal and nitrification, as well as sludge production and population dynamics through the ratio of active nitrifiers/bacteria. Both steady-state and transient conditions could be described accurately by the model, except for technical problems or sudden variations in the wastewater composition.
Assessment of biological activity during temperature changes in a bench-scale sequencing batch reactor fed with synthetic medium containing lignin
Authors: Kriebitzsch Klaus , Adamietz Elke , Schiegl Christian , Helmreich Brigitte , Wilderer Peter A. , Wuertz Stefan
Published: May 2018

The influence of temperature on activated sludge in a bench-scale SBR fed with a synthetic medium simulating paper mill effluents was determined using biological methods based on the measurement of enzymatic activities. Redox activity inside cells and in the extracellular polymeric substances as well as the proportion of active cells in the sludge were measured by the reduction of the tetrazolium salts XTT and CTC, respectively. A significant shift in the size distribution of lignin at 30°C correlated with a maximum of extracellular redox activity. The percentage of active cells in the biocoenosis was independent of temperature. α-glucosidase and L-alanine-aminopeptidase activities were steady at 20, 30 and 40°C. After shifting the temperature to 50°C there was an enormous short-time increase of both enzyme activities because of the change from mesophilic to thermophilic conditions. Of the biological parameters tested, only extracellular redox activity correlated with degradative activity as detected by a change in molecular size distribution of lignin molecules.
Loss of volatile organics from kraft bleaching filtrates in the evaporation/drying phase of the analysis for dissolved total solids (DTS) and dissolved volatile solids (DVS)
Authors: Luonsi A. , Lehtonen M. , Deleuze S. , Pönni S. , Halttunen S.
Published: May 2018

Measurement for describing dissolved organic matter (DOM) was needed to calibrate bleached kraft process model. Volatile solids (VS) measurement from filtered sample (DVS) was chosen as closest possible, especially because it is readily available and easy to perform. The extreme conditions of kraft chlorine dioxide bleaching filtrates (e.g. pH 2–11), however, prerequisite evaluation of the analyzing method in these circumstances. Measurements before and after evaporation/drying (SFS 3008) and redissolution showed that considerable amounts of dissolved organic carbon (DOC) escaped from acid filtrates. When identified, particularly alcohols, carboxylic acids but also aldehydes and ketons covered the majority of the disappeared quantity. According to DOC the escaped share was from 17 to 37% in the acid filtrates depending on stage (D0/D1/D2) and conditions in production process. In alkaline bleaching stage filtrates the share was 4 to 9%. The major identified volatilized compounds in D0-filtrate were methanol and formic acid. They represented 94% of the identified compounds. Identified volatilized quantity from D0-filtrate in DVS measurement represents about 4–5 kg per metric air dry ton of pulp as discharge. The carbon of the identified volatilized compounds covered 63% of the loss measured as DOC. Knowledge of volatiles and process conditions is required when DVS is used for DOM description in kraft bleaching filtrates.
Heavy metal biosorption by white-rot fungi
Authors: Yetis Ülkü , Özcengiz Gülay , Dilek Filiz B. , Ergen Neslihan , Erbay Alev , Dölek Ayla
Published: May 2018

In this study, heavy metal biosorption potentials of two white-rot fungi, Polyporous versicolor and Phanarochaete chrysosporium, which are commonly used in wastewater treatment were determined. Biosorption studies were performed for Cu(II), Cr(III), Cd(II), Ni(II) and Pb(II) at the same operational conditions and the effectiveness of both fungi at removing these heavy metals was compared. It was found that both P. versicolor and P. chrysosporium were the most effective in removing Pb(II) from aqeous solutions with maximum biosorption capacities of 57.5 and 110 mg Pb(II)/g dry biomass, respectively. With P. versicolor, the adsorptive capacity order was determined to be Pb(II)>Ni(II)>Cr(III)>Cd(II)>Cu(II) whereas the order was Pb(II)>Cr(III)>Cu(II)=Cd(II)>Ni(II) with P. chrysosporium. As a general trend, metal removal efficiency with these fungi decreased as the initial metal ion concentration increased.
Influence of oxygen limitation on the cell surface properties of bacteria from activated sludge
Authors: Palmgren R. , Jorand F. , Nielsen P. H. , Block J. C.
Published: May 2018

Cell surface hydrophobicity is believed to be important to flocculation in activated sludge and biofilm systems. Optimization of these processes includes changes in the growth conditions of the bacteria. A number of factors influence cell surface hydrophobicity. The influence of oxygen on the cell surface hydrophobicity of 4 bacteria isolated from activated sludge was tested. The bacteria were grown in batch cultures with and without oxygen limitation. It was found that oxygen limitation generally caused a lowering of the cell surface hydrophobicity. The study also showed that there are many difficulties in measuring cell surface hydrophobicity since other cell surface properties, such as surface charge, influence the measurement methods. The MATH test was employed to establish how assay conditions influenced the results.
The relationship between the structure of activated sludge flocs and the sorption of hydrophobic pollutants
Authors: Finlayson J. C. , Liao B. , Droppo I. G. , Leppard G. G. , Liss S. N.
Published: May 2018

The relationships between the structure of minimally perturbed activated sludge flocs and the sorption of organic contaminants were studied. Sorption, settling velocity, size distributions, floc structure and EPS composition were all examined. The results show significant removal of selected halogenated hydrocarbons and polycyclic aromatic hydrocarbons by biosorption to activated sludge flocs. However, statistically significant effects on the settling or size of the flocs caused by this sorption were not observed. The addition of chromium (Cr(III)) metal ions to the biomass caused observable changes in the floc structure and decreased ruthenium red binding to the acidic polysaccharides of the floc matrix. At low concentrations (0.6 mg/l), chromium caused an increase in the sorption of organic compounds to flocs, suggesting that changes in the floc structure can be induced, which can have an impact on the sorption of pollutants to the flocs.
Control and modeling of membrane fouling due to microorganism growth by UV pretreatment
Authors: Otaki M. , Takizawa S. , Ohgaki S.
Published: May 2018

Control of membrane-fouling is an important topic for extending continuous running time and reducing the frequency of chemical cleaning in membrane processes. Since the microorganism contribution to membrane fouling was considered to be significant, UV was thought to be effective to control membrane fouling. In this study, a pilot plant scale MF-membrane system (flow rate = 5 m3d−1) was operated in order to investigate the effect of UV pretreatment. As the experimental results, it was found that UV irradiation prevented the membrane fouling by control the microorganism concentration in the feed. And the continuous running time of membrane was extended 6 times longer than that of a process without UV pretreatment. In order to know how UV pretreatment prevented fouling, we also investigated the residual bactericidal effect which persists in water even after UV irradiation. However, the residual bactericidal effect wasn't observed in our experiment, therefore inhibition of microorganism growth by the residual effect in the membrane module could be ignored. We developed the theoretical model of microorganism growth on membrane as a membrane fouling material. This model can explain the observed membrane fouling due to microorganism growth.
The use of 16S rDNA clone libraries to describe the microbial diversity of activated sludge communities
Authors: Blackall Linda L. , Burrell Paul C. , Gwilliam Heather , Bradford Debbie , Bond Philip L. , Hugenholtz Philip
Published: May 2018

Clone libraries were prepared from polymerase chain reaction amplified 16S rDNAs from activated sludge community DNAs. Eight different libraries from a range of samples were prepared. From each library, up to 100 clones were examined. In some libraries, the clone inserts were grouped into operational taxonomic units (OTUs) by restriction enzyme analysis (REA). Then, either the clones or representatives of OTUs were partially sequenced using either 27f or 530f conserved bacterial primers. The sequence data was phylogenetically analysed to group the clones and the method currently gives the best insight into the activated sludge microbial community biodiversity. The method for clone library production is described and the pros and cons of the procedure are outlined. In summary, the use of clone libraries has resulted in the discovery of unimagined biodiversity in activated sludge. The abundance of some unpredicted bacterial groups (e.g. beta subclass Proteobacteria) and the paucity of expected ones (e.g. Acinetobacter) highlights the inadequacy of traditional culture dependent methods that rely on sample dilution and spread plate inoculation.
Dehydration of acetic acid/water mixtures by pervaporation with a poly(4-methyl-1-pentene)/Co (III)(acetylacetonate) blend membrane
Authors: Lee Jiunn-Fwu , Wang Yi-Chieh
Published: May 2018

For dehydrating aqueous acetic acid solution by pervaporation, a poly (4-methyl-1-pentene)/Co(III) (acetylacetonate), TPX/Co(acac)3, blend membrane was synthesized. The effects of Co(acac)3 content, feed compositions, feed temperature, and degree of swelling on pervaporation performance were investigated. The stability of the blend membrane was examined by ultraviolet study. Water molecules preferentially dissolve in the TPX/Co(acac)3 membrane and also predominantly diffuse through the membrane. A separation factor for water of 154 and a 163 g/m2-h permeation rate with a 10 wt% Co(acac)3 content TPX/Co(acac)3 blend membrane for pervaporation of 80 wt% acetic acid feed concentration were obtained.
Characterization of filamentous foaming in activated sludge systems using oligonucleotide hybridization probes and antibody probes
Authors: de los Reyes Francis L. , Oerther Daniel B. , de los Reyes Ma. Fiorella , Hernandez Mark , Raskin Lutgarde
Published: May 2018

A quantitative method was developed for estimating Gordona mass in activated sludge foam and mixed liquor samples. The technique involves in situ hybridization with a genus-specific fluorescently labeled oligonucleotide probe calibrated on pure cultures of Gordona. The immunofluorescent technique of Hernandez et al. was modified to allow staining with fluorescently labeled antibody and hybridization probes. The results of this technique were compared to those from membrane hybridization studies using radioactively-labeled oligonucleotide probes. Quantitative membrane hybridizations, in situ hybridizations, and antibody staining resulted in significantly different levels of Gordona in activated sludge foam, activated sludge mixed liquor, return activated sludge, and anaerobic digester sludge. Simultaneous staining with labeled antibodies and oligonucleotide probes provide a definitive identification for Gordona, and represents a new approach for in situ studies of this organism's role in foaming.
Anaerobic uptake of glutamate and aspartate by enhanced biological phosphorus removal activated sludge
Authors: Satoh Hiroyasu , Mino Takashi , Matsuo Tomonori
Published: May 2018

Mechanisms of the anaerobic uptake of glutamate and aspartate by enhanced biological phosphorus removal activated sludge were investigated. Sludge hydrolysate with hydrochloric acid was analyzed by reverse phase HPLC after pre column derivatization with dabsyl-chloride. The experimental results indicated that glutamate is accumulated as a polymer consisting of γ-aminobutyric acid and an unknown amino acid. On the other hand, aspartate was found to be deaminated and then accumulated as PHA.
Modeling of enhanced biological phosphorus removal in a sequencing batch biofilm reactor
Authors: Morgenroth Eberhard , Wilderer Peter A.
Published: May 2018

A biofilm system operated for enhanced biological phosphorus removal is evaluated using a mathematical model. The influence of the influent COD concentration and the biofilm thickness are investigated. In an activated sludge system increasing the influent COD will result in a decrease of the effluent phosphorus concentration. However, in a biofilm system above a certain influent COD concentration not all COD supplied in the influent can be taken up during the anaerobic period. Other heterotrophic bacteria will then dominate the biofilm resulting in an increase of the effluent phosphorus concentration. A larger biofilm thickness will result in an increase of the total mass of polyphosphate-accumulating organisms in the system. However, it is shown that a larger biofilm thickness results in higher effluent phosphorus concentrations. The mathematical model presented is based on the IAWQ Model No. 2 modified for the biofilm system. Mass transport in the biofilm is modeled one-dimensionally. Removal of biomass through backwashing and, thus, removal of phosphorus, is included in the mathematical model. Simulations were used to explain experimental observations.
Mobility of contaminants in relation to dredging operations in a mesotidal estuary (Tagus estuary, Portugal)
Authors: Vale Carlos , Ferreira Ana M. , Micaelo Cristina , Caetano Miguel , Pereira Eduarda , Madureira Maria J. , Ramalhosa Elsa
Published: May 2018

During the construction of a New Bridge over the Tagus estuary 2.5 million tons of sediments were dredged, part of this quantity being contaminated material. The extension and intensity of the water turbidity associated with dredging operating varied with the tidal conditions but the resuspended material collected near the bucket dredger did not present a concentration increment in metals and PCB, when compared to the estuarine suspended sediments. The calculated distribution coefficients suggest that some contaminants in solids near the dredger were not in equilibrium with the water. A 24-hour laboratory experiment demonstrated the complexity and quickness of anoxic sediments oxidation. In such a short period of time metals in the solids change their fractionation. A second laboratory simulation showed that mussels accumulate metals and PCB congeners when placed in turbid aerated water.
Contamination and toxicity trends for sediments — case of the elbe river
Authors: Heininger P. , Pelzer J. , Claus E. , Tippmann P.
Published: May 2018

The paper deals with sediment studies in the Upper and Middle Elbe between 1991 and 1996. Hydrological and seasonal factors are discussed with respect to trends in sediment contamination. An investigation programme is described including periodical measurements of inorganic and organic pollutants at monitoring stations as well as in-depth case studies. In these studies reference sites represent background conditions. Heavily contaminated reaches are taken as the worst case scenario. An integrated approach is applied combining chemical and ecotoxicological investigations. Factors are defined which must be taken into account in order to draw reliable conclusions for sediment quality. Contamination trends and trends in sediment toxicity are derived for the river Elbe.
Distribution of metals in sediments of the elbe estuary in 1994
Authors: Groengroeft Alexander , Jaehnig Ursula , Miehlich Guenter , Lueschow Rolf , Maass Vera , Stachel Burkhard
Published: May 2018

In 1994 the quality of the uppermost sediment layer of the Elbe estuary was surveyed for various planning purposes. For example, metal contents were determined in the grain-size fraction <20 μm, and the concentrations of PAH were analyzed in the total sample, with correcting for grain-size effect being done numerically. Using the specific zinc contents in fine-grained particles, transport phenomena were recognized: particles of marine origin are transported >100 km upstream to the Hamburg area, causing contamination to decrease to about 50% of the fluvial level. The local metal contamination however varies strongly. Samples with low concentration could be detected as geogen; the samples with the highest level of contamination were assumed to have originated from periods of higher river pollution. Of the samples, 74% with medium enrichment factors (2 to 8.5 vs. background for Zn) were suspected to reflect the actual contamination level. Compared to previously reported quality criteria, sediment samples from the upper part of the estuary are still highly contaminated. In the outer part of the estuary the quality is better, but because the marine fine-grained particles still have contamination levels to class II-III in the ARGE Elbe classification system, a further reduction of sediment contamination in the whole estuary would be limited to this level.
Fractionation of heavy metals in sediment cores from the Ell-Ren River, Taiwan
Authors: Tsai L. J. , Yu K. C. , Chang J. S. , Ho S. T.
Published: May 2018

Fractionation of heavy metals (Cr, Cu, Co, Zn, Ni, and Pb) in sediment cores taken from three heavily polluted locations of the Ell-Ren River in southern Taiwan was studied. After the three sediment cores were separated into several depth sections, sequential extraction procedure was used to determine the variations in heavy metal binding fractions (exchangeable, bound to carbonates, bound to Mn oxides, bound to Fe oxides, and bound to organic matter) with different sediment depth, and followed by multivariate analyses. It turns out that a deeper sediment depth tended to result in smaller amounts of total extractable heavy metals (TEHMs), indicating that heavy metal pollution of the river has been intensifying these years. The decreasing order of TEHMs was: Zn > Cu > Pb > Cr > Ni > Co. The TEHMs Zn and Cu detected from different depth of the three sediment cores were mainly originated from “bound to carbonates” and “bound to organic matter” fractions, respectively. Also, the percentages of the heavy metals contained in each of the five binding fractons only slightly varied with sediment depth. From multivariate analyses, all the heavy metals except Co behaved similarly and might be discharged from the same pollution sources.
Ecotoxicity of contaminated sediments, a matter of bioavailability
Authors: Kaag N. H. B. M. , Foekema E. M. , Scholten M. C. Th.
Published: May 2018

Marine and freshwater mesocosm-scale experiments with contaminated sediments have shown that there is a direct relationship between the accumulated contaminant levels and the feeding habits of the organisms used. The highest levels of PAHs and PCBs were found in the sediment feeding lugworm Arenicola marina and in Tubifex worms. The levels of contaminants in the suspension feeding mussels Mytilus edulis and the zebra mussels, Dreissena polymorpha, were not influenced by the contaminant content of the sediments, but were related instead to the level of contaminants in the sea water above. Intermediate levels were found in the baltic tellin, Macoma balthica, which is a filter feeder as well as a deposit feeder, depending on the availability of food.

These results show that there is no simple relationship between contaminant concentration in the sediments and bioavailability. Higher levels of contaminants do not necessarily lead to higher levels of these contaminants in Arenicola, due to differences in the sediment structure and the ageing of the contamination. On the other hand, toxic effects are related to the internal concentrations of certain chemicals. The internal concentrations observed in Arenicola may provide a good estimation of the true bioavailability of sedimentary contaminants and can also be used as an indicator for potential environmental effects.