Dissertations / Theses on the topic 'Activated sludge'
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1
Mebrahtu, Michael Kidane. "Aerobic digestion of waste activated sludge from biological nutrient removal activated sludge systems." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5025.
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Includes bibliographical references.Waste activated sludge (WAS) is a biological sludge that contains biodegradable and non-biodegradable volatile suspended solids (VSS) and non-volatile inorgainic suspended solids (ISS). Stabilization for safe disposal of the WAS is a process of paramount importance at wastewater treatment plants (WWTPs). Hence, aerobic digestion of the WAS from biological nutrient removal (BNR) activated sludge (AS) systems was carried out under batch conditions to (1) measure changes in nitrogen and phosphorus concentrations in solid and liquid phases during aerobic batch digestion tests (2) simulate the parent system with Activated Sludge Model No. 2 (ASM-2) in AQUASIM computer program to obtain the initial conditions for batch test simulation (3) simulate the batch aerobic digestion process with ASM-2 and compare with experimental data (4) develop VSS-based and total suspended solids (TSS) (with the addition of ISS to the VSS-based) batch reactor and steady state models for aerobic digestion of nitrification denitrification biological excess phosphorus removel (NDBEPR) WAS based on the individual biomass die-off rates of phosphorus accumulating organisms (PAOs) and ordinary heterotrophic organisms (OHOs), and (5) evaluate the ASM-2 simulation results with steady state aerobic batch digestion model.
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Shi, Xinlong. "Membrane fouling of activated sludge." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B30731884.
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Shi, Xinlong, and 史昕龍. "Membrane fouling of activated sludge." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30731884.
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Evenett, K. M. "Activated sludge : Surface properties and settlement." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380061.
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Humphreys, Paul Nigel. "Biological denitrification in activated sludge systems." Thesis, London South Bank University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303974.
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Park, Chul. "Cations and activated sludge floc structure." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34253.
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This research was designed to investigate the effect of cations on activated sludge characteristics and also to determine their influence on digestion performance. For this purpose, cations in solution and in floc were evaluated along with various activated sludge characteristics and the collected waste activated sludge underwent both anaerobic and aerobic digestion. It was found that large amounts of biopolymer (protein + polysaccharide) remained in the effluent of WWTP that received high influent sodium but had low iron and aluminum in floc. However, sludges from plants with high sodium and high iron and aluminum dewatered well and produced high quality effluents, suggesting that iron and aluminum have significant positive effects on floc properties. Following anaerobic digestion, a significant increase in solution protein occurred and correlations between solution protein, ammonium production, percentile volatile solids reduction and iron in floc were obtained. These data indicate that iron-linked protein is released to solution when iron is reduced and its degradation is responsible for volatile solids reduction in anaerobic digestion. In aerobic digestion, polysaccharide in solution increased along with calcium, magnesium and inorganic nitrogen. This implies that divalent cation-bound biopolymer might be the primary organic fraction that is degraded under aerobic digestion. Combined (anaerobic/aerobic) digestion was performed and produced further volatile solids destruction with discrete cation and biopolymer response during each phase of digestion. These results support the theory that two types of organic matter with different cation bindings are present in floc and each type is degraded under different digestion processes.Master of Science
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Kim, Min-Jin. "The effect of sludge retention time on dewaterability of activated sludge." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58745.pdf.
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Burke, Russell Armstrong. "Biological excess phosphorus removal in short sludge age activated sludge systems." Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/7582.
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Includes bibliography.The objective of this investigation was to test, at laboratory-scale, the behaviour of short sludge age biological excess P removal systems, to assess the response of the systems under non-nitrifying and nitrifying conditions, to determine the optimal system configuration(s) and operational parameters, and to check the settling characteristics of the mixed liquor produced in the systems. A secondary objective was to use the observed response data to test the predictive qualities of both the general activated sludge model of Dold, Ekama. and Marais (1985) and the semi-empirical biological excess P removal model of Wentzel, Dold, Ekama and Marais (1984). The objectives were fulfilled by operating a number of laboratory scale anaerobic/aerobic and anaerobic/anoxic/aerobic systems with varying sludge ages, anaerobic, anoxic and aerobic mass fractions, mixed liquor recycle ratios and COD loading rates.
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Liu, Xiaoling. "Laboratory evaluation of microbial aggregation in activated in activated [sic] sludge." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202501487/.
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Kabouris, John C. "Stochastic control of the activated sludge process." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/20306.
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Christopher, Lisa Joy. "Enhancement of polyether biodegradation in activated sludge." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/25378.
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Goodwin, Julian A. S. "Surface chemistry in the activated sludge process." Thesis, University of Birmingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365891.
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Samuelsson, Pär. "Control of Nitrogen Removal in Activated Sludge Processes." Doctoral thesis, Uppsala University, Department of Information Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5903.
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More stringent requirements on nitrogen removal from wastewater are the motivation for this thesis. In order to improve treatment results and enhance cost-efficient operation of wastewater treatment plants, model based control strategies are presented.
A Java based simulator for activated sludge processes (JASS) is presented. The graphical user interface, educational experiences and implemented control strategies are discussed.
Controlling the addition of an external carbon source is the next topic discussed. A simple model based feedforward controller is derived and evaluated in a simulation study. The controller attenuates process disturbances quickly. Further, two feedforward controllers for adjusting the aeration volume in activated sludge processes are derived. The aim of the volume control strategies was to efficiently dampen the impact of process disturbances without using an excessively high dissolved oxygen concentration. The simulation results are promising and show that the aeration volume may be a feasible control variable.
A linearisation method for static input non-linearities is presented. The method gives essentially the same result as the existing standard method, but possesses some implementational advantages. The method is used to linearise the non-linear oxygen transfer function of an activated sludge process in an application study.
Multivariable interactions in a process model describing nitrate removal in an activated sludge process are studied using the well known RGA method as well as a relatively novel tool based on Hankel norms. The results of the analysis are compared to conclusions drawn from common process knowledge and are used to design a multivariable control strategy. It was found that process disturbances may be rejected faster using multivariable control.
Finally, the operational costs of the denitrification process are investigated and visualised graphically. Cost optimal regions are found by a numerical grid search. Procedures for controlling the denitrification process in a cost-efficient way are described.
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Henkel, Jochen [Verfasser]. "Oxygen Transfer Phenomena in Activated Sludge / Jochen Henkel." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2010. http://d-nb.info/1106115945/34.
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Keech, Gregory Wade. "The impact of paper additives on activated sludge." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29380.pdf.
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Xu, Kai Harper Willie F. "Thermodynamics of steroid estrogen sorption to activated sludge." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/FALL/Civil_Engineering/Thesis/Xu_Kai_29.pdf.
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Moreno, Oswaldo. "Design of the step-feed activated sludge process." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64054.
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Skelton, Hedley John. "Applying hydrodynamic cavitation to the activated sludge process." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613352.
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Viloria, Ysabel. "Sensitivity Analysis of the UNO Activated Sludge Model." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/540.
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Different types of mathematical models have been proposed to predict the activated sludge process final effluent quality. La Motta (2004b) developed a mathematical model linking the operating parameters of an activated sludge system and the classical limiting flux sludge settling theory. This project studies the estimation of the unknown parameters of La Motta's model and also the model's sensibility. To obtain unknown parameters true values Full Information Maximum Likelihood (FIML) estimator is used, it will converge on a set of values that satisfy all the estimating equation simultaneously. Favorable results were obtained when correlations are applied between predicted values using estimated kinetics parameters and the observed values obtained from activated sludge pilot plant located within installations of the Marrero Wastewater Treatment Plant, New Orleans, Louisiana. Constructive results about the sensibility of the model are also obtained demonstrated that the model is affected significantly to the variation of some kinetics parameters.
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Segall, Martha. "The effects of cations on activated sludge characteristics." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45911.
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This research was prompted by a field study performed at the Celanese Corporation Wastewater Treatment Plant, Narrows, VA., in which calcium chloride addition had improved sludge characteristics that were believed to have deteriorated because of sodium hydroxide additions for pH control.
Research objectives were to determine whether the observed improvements during the full-scale plant study were caused by the addition of divalent cations and whether the deterioration of the sludge was due to sodium ion additions.
Bench-scale, activated sludge reactors were fed wastewater from the Celanese plant to model plant conditions. Sodium was added in an attempt to cause deterioration of the sludge characteristics. Magnesium and calcium were used as divalent cations to try to improve the sludge characteristics.
Results of the study indicated that the magnitude of the effects seen in the full-scale plant study could not be reproduced in the laboratory. Magnesium produced little or no effect on the system and calcium improved the sludge characteristics slightly. Sodium caused deterioration of the sludge but not as dramatically as the full-scale study. This suggested that sodium alone did not adversely affect the sludge but rather, sodium hydroxide might have been combined with organics in the waste which then affected the system.
Master of Science
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Wentzel, Mark Charles. "Biological excess phosphorus removal in activated sludge systems." Doctoral thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/8309.
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Includes bibliographies.When this investigation was commenced in 1983 two activated sludge systems had been developed in South Africa that accomplish biological excess phosphorus (P) removal, the UCT and modified Bardenpho systems. To predict the P removal in these systems, an empirical model had been developed. In the empirical model, P removal was formulated in terms of some of the system parameters, such as anaerobic mass fraction, available readily biodegradable COD and active mass concentration. Organisms directly implicated in biological excess P removal (poly P organisms) did not feature in the model and the P removal was not linked to any basic biological or biochemical behaviour. Clearly, there was a need for a more fundamentally based model. The objective of this thesis was to develop such a model.
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Yeh, Kuei-Jyum. "The influence of cations on activated sludge behavior." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/54375.
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This study investigated the influence of cations on biopolymer characteristics and sludge properties. Settling and dewatering properties of sludges were measured and correlated to the biopolymer characteristics. In addition, effects of cations on sludge conditioning with polymer were studied.
Experiment mainly consisted of two parts, reactor study and batch study. In re- actor study continuous-flow reactors were operated. Variables used included varying types of substrate, addition of magnesium or sodium, and changes in pH. The batch study included conditioning tests on the sludges with combinations of cationic polymer and salts.
Biopolymers were extracted using alkali extraction followed by gel filtration and subsequent carbohydrate and protein analysis. The sludge settling and dewatering were measured in terms of SVI and specific resistance, respectively. Sludge filtering rate (TIF) was used to measure the conditioning efficiency.
The results indicated that the influence of cations depended on the type and concentration of salt. An optimal concentration of Mg was found to improve biopolymer binding. The organic composition of feed also affected biopolymer characteristics. A higher pH combined with a high amount of sodium released biopolymer and resulted in sludge deflocculation. A relationship between unbound biopolymer and soluble effluent COD was observed but no discernible relation between biopolymer binding and sludge settling and dewatering properties was found. Cations were found to reduce polymer requirement during sludge conditioning.
In addition, the amount of extractable biopolymers by alkali extraction was greatly influenced by salt. Magnesium inhibited the release of biopolymer, but sodium im- proved the efficiency of biopolymer extraction.Master of Science
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Jordan, Mark. "Activated Sludge Bioassays for Rapid Biochemical Oxygen Demand." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/367704.
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A number of recent studies have described new rapid biochemical oxygen demand (BOD) methods. However, most have not maintained the features that make the 5-day standard BOD assay particularly relevant to wastewater management – a high level of substrate bio-oxidation and use of wastewater treatment plant (WWTP) sludge as the biocatalyst. In a critical breakthrough, return activated sludge (RAS) from Coombabah WWTP, southeast Queensland, was successfully incorporated as the biocatalyst in a ferricyanide mediated-BOD (FM-BOD) bioassay. The bioassay was initially optimized for the measurement of highly variable and complex wastewaters, particularly trade wastes, by maximizing the analytical working range (10 – 170 mg BOD5 L-1) and extent of substrate degradation (96 ± 23% of measured BOD5 oxidation). A highly significant correlation (n = 35; slope = 1.07; R = 0.95; incubation time = 6 h) was found between this RAS FM-BOD and standard BOD5 assays using a range of real trade waste samples.
The activated sludge FM-BOD bioassay was re-examined with the goal of measuring low–mid range wastewaters (i.e. treated effluents and WWTP influents) that comprise the bulk of all BOD samples analyzed worldwide. All experimental parameters were re-optimized, primarily to improve the detection limit of the FM-BOD assay to approximate that of the standard BOD5 assay (i.e. ≈2 mg BOD5 L-1). Primary influent sludge (PIS) from Coombabah WWTP was the most favorable sludge trialed, with the new bioassay having an analytical range of 2 – 40 mg BOD5 L-1. A highly significant correlation (n = 33; slope = 0.94; R = 0.96; incubation time = 3 – 4 h) was observed between the PIS FM-BOD and standard BOD5 assays using a range of treated effluent, influent and grey water samples.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Rojas, Jose Angel. "Relationship between the sludge settling characteristics and the parameters of the activated sludge system." ScholarWorks@UNO, 2004. http://louisdl.louislibraries.org/u?/NOD,171.
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Thesis (M.S.)--University of New Orleans, 2004.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Environmental Engineering."--Thesis t.p. Vita. Includes bibliographical references.
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Punrattanasin, Warangkana. "The Utilization of Activated Sludge Polyhydroxyalkanoates for the Production of Biodegradable Plastics." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27107.
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Sequencing batch reactor (SBR) systems were used for the development of a system and operating procedures for the high production of polyhydroxyalkanoates (PHAs) by wastewater treatment (activated sludge) bacterial cultures. It was found that unbalanced growth conditions stimulated massive PHA production in activated sludge biomass. Operating conditions had a significant effect on PHA production and the composition of the accumulated copolymer when either laboratory prepared mixtures of organics or a high acetic acid industrial wastewater were used as the organic substrate mixture. Fully aerobic (AE) conditions with nitrogen (N) and phosphorus (P) limitations were the optimum conditions for PHA production when the laboratory prepared mixtures of orgnics were used, while fully AE with the combinations of N, P, and potassium (K) limitations were better for PHA production using a high acetic acid industrial wastewater as the substrate. One nutrient limitation or partial limitation of either N or P as used for commercial production using pure cultures did not promote massive PHA production in activated sludge biomass compared to the combination of nutrient limitations. A maximum cellular PHA accumulation of 70%TSS was obtained under fully AE conditions with multiple alternating periods of growth and N&P limitations. Microaerophilic/aerobic (MAA/AE) or anaerobic/aerobic (AN/AE) cycling promoted less PHA production compared to fully AE conditions. The relative amounts of the PHA copolymers formed, i.e., polyhydroxybutyrate (PHB) and polyhydroxyvalerate (PHV) were different under different operating conditions, even though the types and amounts of volatile fatty acids (VFAs) in the feed were the same. It was determined that high total phosphorus (TP) content inside the bacterial cells had a significant detrimental impact on PHA production by activated sludge biomass. A two-stage bioprocess was a better approach for obtaining activated sludge PHA accumulation because a growth phase was necessary to grow the bacterial population that contains minimal TP before starting the subsequent PHA accumulation phase. Seeding sludge obtained from a conventional fully aerobic wastewater treatment system was more suitable than seed obtained from a biological phosphorus removal (BPR) system because bacterial populations from BPR systems tended to convert organic substrates to intracellular carbohydrate content rather than PHA under nutrient limitation conditions. The molecular weights and melting point temperatures of PHAs produced by the mixed culture of activated sludge biomass were comparable to those obtained from pure cultures and have the potential to be used for commercial applications. The results of this study indicate that activated sludge biomass has considerable potential for PHA production for commercial purposes, and likely could do so utilizing wastewater sources of organics. In particular organic rich, nutrient limited wastewaters have potential for efficient PHA production.Ph. D.
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Brennan, Daniel. "The numerical simulation of two phase flows in settling tanks." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248344.
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Turtin, Ipek. "Investigation Of Activated Sludge Bioflocculation: Influence Of Magnesium Ions." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606605/index.pdf.
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Activated sludge systems are the most widely used biological wastewater treatment processes all over the world. The main working principles of an activated sludge system are the oxidation of biologically degradable wastes by microorganisms and the subsequent separation of the newly formed biomass from the treated effluent. Separation by settling is the most troublesome stage of an activated sludge process. A decrease in the efficiency of the separation of microbial biomass from the treated effluent causes a decrease in the overall efficiency of the treatment plant. The efficiency of the separation process is related to the bioflocculation, which can be briefly defined as the aggregation of the bacteria into flocs through flocculation. Bioflocculation depends on the extracellular polymers (EPS) that are produced by microorganisms. The operating conditions of the activated sludge system is a key determinant of the synthesis of EPS and bioflocculation. The main objective of this study is to find out the effect of magnesium ions on the bioflocculation process under phosphorus deficient and sufficient conditions. In order to achieve this aim, the effects of magnesium ion in 4 different concentrations (0.9, 5, 10 and 20 meq/L) are investigated in semi continuous reactors. The reactors are operated at a mean cell residence time of 8 days and 20ºC temperature. When reactors are confirmed to be at steady state, several sets of analysis are conducted. In particular, the surface chemical parameters including EPS and its components, electrical charge, and hydrophobicity as well as physical properties such as settlability, filterability, viscosity, floc strength, and turbidity are examined. It has been understood that phosphorus deficiency causes severe filamentous bulking under magnesium rich conditions. Increasing the phosphorus concentration in the influent can cure this problem. After the sludges are cured some granular structures were observed in the microscopic investigations and they are thought to be polyphosphate granules in which microorganisms tend to accumulate phosphorus when they find the adequate source after a starvation period. To consider the reactors operated at phosphate present conditions, it has been found that EPS increases with increasing influent magnesium concentration. However, protein type EPS (EPSP) exhibits a sharper increase when compared to the carbohydrate type EPS (EPSC) indicating the selective attitude of magnesium ions to protein type of polymers. It has been understood that the increase in the influent magnesium concentration results in an increase in dewaterability and zone settling velocity, and a decrease in the viscosity. Hydrophobicity was found to exhibit a maximum value at 10 meq/L magnesium fed sludge and then it dropped back. Surface charge values also made a minimum at 10 meq/L reactor and then no change occurred at the increase of the magnesium concentration to 20 meq/L. Finally, COD values were found to increase with the increasing magnesium concentration due to the increasing EPS.
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Shahriari, Zavareh Haleh. "Evaluation and modeling of a membrane activated sludge system." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26395.
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A membrane activated sludge bench-scale system was used to treat a complex synthetic wastewater over a wide range of operating conditions ranging 1 to 15 day(s) solids retention time (SRT) and 4 to 12 hours hydraulic retention time (HRT). Although the membrane reactor was able to provide good to excellent separation of particulates from the liquid in the mixed liquor over these operating conditions, the membrane failed, primarily due to clogging at operating conditions outside of these ranges. Various techniques, such as coagulant addition, were attempted to further expand the operating range but they failed. All runs were conducted until steady state conditions existed at which time data for modelling were collected. Performance of the system primarily for carbon and nitrogen removal is described for conditions where solids loss or clogging was nonproblematic. Different mathematical models to predict the behaviour of an activated sludge system and to estimate stoichiometric and kinetics parameters are presented. (Abstract shortened by UMI.)
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Wos, Melissa Louise, and n/a. "Methods For Understanding Bacterial Metabolic Activity In Activated Sludge." Griffith University. School of Environmental Engineering, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20061031.151641.
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Biological wastewater treatment relies on the diverse and complex metabolic activities of bacteria to remove pollutants. Its success depends on the metabolic efficiency of the bacteria. Activated sludge models use parameters that attempt to depict bacterial growth and metabolic processes. However, current methods do not separate metabolic activity from growth and maintenance. As a result, activated sludge processes are misinterpreted or over-simplified. Alternative methods for gauging bacterial activity have been proposed and include the measurements of cellular derived compounds that relate specifically to energy cycling and include Nicotinamide Adenine Dinucleotide [NADH]. To date, NADH has been largely measured within activated sludge using commercial online fluorimeters with in situ probes. However, this current method provides a measure of the 'bulk' (raw) fluorescence within the system, resulting in difficulties when interpreting fluorescence data and poor sensitivity for detecting changes in intracellular [NADH]. This study has developed a more reliable method for estimating intracellular [NADH] and thus metabolic activity within activated sludge systems. Separating extracellular from intracellular [NADH] in samples was crucial because NADH was released and accumulates in the extracellular environment at a concentration of 200 ~M immediately following bacterial death or lysis. This concentration did not decline overtime. This not only caused high background fluorescence but also reduced the sensitivity of detection for changes in intracellular [NADH]. In particular, considerably higher [NADH] values to those from the extracellular suspensions were obtained following extraction of the intracellular material, suggesting that the cell membranes were not being penetrated by the excitable light source. Of the extraction procedures examined, filtration followed by extraction of the intracellular material with a hot Tris buffer was the most efficient and was recommended for accurate estimates of intracellular [NADH] in situ. In addition, standards were used to quantify NADH (moles per cell and/or unit volume) from unknown samples. The limits of detection were found to be 1.058 - 353 uM, whereas concentrations above 353 jAM self-quenched. Sample concentrations were always within these limits of detection. Hence, the sensitivity, reliability and experimental application of the original method was improved upon and able to be used for the direct measurement of microbial metabolic activity, something that has not been demonstrated before now. This study found that bacteria have between 106~ I 08 NADH molecules per cell depending on their metabolic state. A highly metabolically active bacterial cell had between 1O6~ tO7 NADH molecules, while a less active bacterial cell had between to7 -to8 NADH molecules. These measurements of metabolic activity were simultaneously monitored alongside other measures of bacterial growth, such as the incorporation of radiolabelled thymidine into DNA as a direct measure of DNA replication (new cell synthesis), the incorporation of radiolabelled leucine into protein as a direct measure of protein synthesis, oxygen uptake rates (OUR) as a direct measure of respiration, ATP as a measure of potential energy and dissolved organic carbon (DOC) as a measure of substrate assimilation. As OUR deceased, bacterial growth (using both the thymidine and leucine assays), specific [NADH] and specific [ATP] increased. High OUR and substrate oxidation rates simultaneous with low specific [NADH] indicated high rates of electron transport and thus efficient metabolic activity. Also, low OUR and substrate oxidation rates simultaneous with high specific [NADHI indicated inefficient rates of electron transport, therefore inhibiting oxidative phosphorylation (ATP production). A lack of oxygen as the terminal electron acceptor did not efficiently reoxidise NADH to NAD and resulted in an accumulation of NADH within the cell. Thus, a measure of low specific [NADHI was linked to the efficient rate of reoxidation of NADH to NAD* and reflects high metabolic efficiency. DNA and protein syntheses were coupled following substrate enrichment (glucose or acetate), indicating that bacteria were in balanced growth. However, DNA and protein syntheses became uncoupled once substrate was depleted, indicating unbalanced growth. An average Leu:TdR ratio of 7.4 was determined for activated sludge and was comparable to values published from marine systems. This ratio increased during log growth phase and decreased during stationary growth phases. Specific growth rates determined using the [3HITdR and [3H]Leu assay yielded values ranging from 2 - 10.5 d' and from 2.5 - 6 d1, respectively and were comparable to published values. Changes in OUR, NADH, ATE', DNA replication and protein synthesis were statistically ordinated using multidimensional scaling, and changes (in magnitude and direction) in bacterial metabolic activity were observed. Such methods enable the tracing of where bacteria divert their energies, such as to growth or maintenance and thus provide a greater understanding of bacterial behaviour in activated sludge. While studying anoxic and anaerobic conditions were beyond the scope of this work, the use of such methods to monitor bacterial metabolic activity under such conditions is warranted.
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Peters, Jennifer. "The activated sludge treatment of pulp and paper wastewater." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0027/MQ50650.pdf.
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Chen, Fei. "Bacterial auto-aggregation and co-aggregation in activated sludge." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1211384981/.
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Peters, Jennifer 1973. "The activated sludge treatment of pulp and paper wastewater /." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21319.
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Biological treatment of pulp and paper wastes by activated sludge is widely practiced in industry to reduce the organic content and toxicity of the wastewater. Most industrial applications require the treatment of a combination of streams from various processes. The composition of the combined stream varies since shock loadings and spills may occur. The objective of this research was to determine the effects of these variations on the microbial community and, ultimately, on the kinetics of the reduction of biological oxygen demand (BOD) and chemical oxygen demand (COD). This will improve the understanding of control requirements for the process.Effluents from two mills in Quebec were examined. Initially, effluents from a chemithermomechanical pulp (CTMP) mill were used in this research. The objective was to study the effect of six different waste streams mixed with total mill effluent (0--100%) on the reduction of COD and on the microbial population. The remainder of this research focused on treating effluents from a Kraft mill and investigated the effect of hydraulic residence time (HRT) and step inputs of 1%, 2.5% and 5% black liquor on the reduction of COD and BOD5 and on the microbial population. (Abstract shortened by UMI.)
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Mayhew, Maxine Eleanor. "Chemical inhibitors for biomass yield reduction in activated sludge." Thesis, Cranfield University, 1999. http://dspace.lib.cranfield.ac.uk/handle/1826/4547.
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Increasing legislation and rising treatment and disposal costs have promoted optimisation of the activated sludge process to encompass reduction of waste biomass. Manipulation of process control such as increasing sludge age and decreasing food to microorganism ratio can lower waste sludge production, but capital works as well as increased operating costs in the form of power requirement for oxygen supply may be required. The need for a cost effective method of biomass reduction without capital expenditure has prompted research into methods beyond process control. The use of chemicals capable of disrupting microorganism metabolic pathways can theoretically allow continuation of catabolic (degradative) paths whilst halting some or all of the anabolic (growth) pathways. This project explored the use of metabolic inhibitors (uncouplers, tricarboxylic acid cycle inhibitors and antibiotics) to reduce the yield of the activated sludge process. Initial respirometric studies identified many chemicals capable of interacting with the activated sludge microorganisms. Increased oxygen uptake rate was taken as an indication of a good uncoupler, and tests highlighted 4 chemicals with significant potential for achieving biomass reduction (trypan blue, rotenone, 2,4 DNP and 4 NP). These chemicals were then tested at a laboratory scale and at bench scale in both batch and continuous simulations. Simulations were carried out using activated sludge and settled sewage feed to obtain as realistic conditions as possible. In batch tests, trypan blue, rotenone and 2,4 DNP successfully reduced mixed liquor suspended solids accumulation with little effect on COD removal compared to controls. In continuous simulations, 2,4 DNP and 4 NP both lowered yield with respect to their relative controls. Rotenone addition did not result in lowered yield. In all cases, any yield reduction was not at the expense of process efficiency in terms of COD and BOD removal. At pilot scale, 2,4 DNP almost halved the observed yield compared to the control whilst having no significant effect on BOD, COD or ammonia removal, nitrite and nitrate production, SVI or CST. Addition of chemical uncouplers had little effect on the species diversity of the activated sludge though a reduction in the floc size was observed in treated samples. Selection of a suitable chemical can result in reduced yield without detrimental effect to process efficiency in the activated sludge process. An increase in oxygen consumption occurred which has an associated cost implication, but this was not found to be significant compared to the savings made by reducing the yield.
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Clough, G. "The flow of activated sludge through polyester monofilament meshes." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374180.
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Barbosa, Vera Lucia. "Biological treatment of hydrogen sulphide by activated sludge diffusion." Thesis, Cranfield University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422391.
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Qi, Bing Cui. "The bio-disposal of lignocellulose substances with activated sludge." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52489.
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Thesis (PhD)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: Lignocellulose is the principal form of biomass in the biosphere and therefore the predominant renewable source in the environment. However, owing to the chemical and structural complexity of lignocellulose substrates, the effective and sustainable utilization of lignocellulose wastes is limited. Many environments where lignocellulose residues are ordinarily stored can be highly acidic (e.g. landfills), and under these circumstances biodegradation of the lignocellulose is slow and unhygienic. Owing to the metabolic activities of the micro-organisms, the initially acidified habitats rapidly undergoes self-neutralization. A number of pathogenic bacteria (coliforms and Salmonella sp.) are present during this slow degradation process and it is therefore imperative to improve the efficiency and hygienic effects of the biodegradation of the lignocellulose. Although the fundamentals of biodegradation of lignocellulose have been widely investigated, many issues still need to be resolved in order to develop commercially viable technology for the exploitation of these waste products. For example, owing to the complex, heterogeneous structure of lignocellulose, the degree of solubilization, modification and conversion of the different components are not clear. Likewise, the overall anaerobic degradation of lignocellulose is not understood well as yet. In this study, the emphasis was on the promotion of solid anaerobic digestion of lignocellulose wastes for environmental beneficiation and waste reutilization. The degradation of lignocellulose in landfill environments was first simulated experimentally. Once the microbial populations and the degradation products of the system were characterized, the promotion of anaerobic digestion by use of activated sludge was studied. This included acidogenic fermentation, as well as recovery of the methanogenic phase. Moreover, special attention was given to the further disposal of humic acids or humic acid bearing leachates formed in the digestive system, since these acids pose a major problem in the digestion of the lingocellulose. With ultrasonication, approximately 50% of the lower molecular weight fraction of humic acids could be decomposed into volatile forms, but the higher molecular weight fraction tended to aggregate into a colloidal form, which could only be removed from the system by making use of ultrasonically assisted adsorption on preformed aluminium hydroxide floes. This was followed by an investigation of the microbial degradation of humic acids and the toxicity of these acids to anaerobic consortia. Further experimental work was conducted to optimize the biological and abiological treatment of lignocellulose in an upflow anaerobic sludge blanket (DASB) reactor fed with glucose substrate. The humic acids could be partially hydrolysed and decomposed by the acid fermentative consortia of the granules in the DASB reactor. Finally, solid mesothermophilic lignocellulose anaerobic digestive sludge can be viewed as a humus-rich hygienic product that can improve the fertility and water-holding capacity of agricultural soil, nourish plants and immobilize heavy metals in the environment as a bioabsorbent.
AFRIKAANSE OPSOMMING: Lignosellulose is die hoofbron van biomassa in die biosfeer en is daarom ook die belangrikste hernubare bron in die omgewing. As gevolg van die chemiese en strukturele kompleksiteit van lignosellulose substrate, is die doeltreffende en volhoubare benutting van lignosellulose afval egter beperk. Die suurgehalte van die omgewings waar lignosellulose reste gewoonlik gestoor word, soos opvullingsterreine, kan hoog wees en onder hierdie omstandighede is die biodegradasie van die lignosellulose stadig en onhigiënies. As gevolg van die metaboliese aktiwiteite van die mikro-organismes ondergaan die aanvanklik aangesuurde habitatte vinnig self-neutralisasie. 'n Aantal patogeniese bakterieë (koliforme en Salmonella sp.) is deurgaans gedurende dié stadige natuurlike proses teenwoordig en dit is dus van die grootste belang om die effektiwiteit en die higiëne van die bioafbreking van die lignosellulose-substraat te verhoog. Alhoewel die grondbeginsels van die bioafbreking van lignosellulose reeds wyd ondersoek is, moet verskeie probleme nog opgelos word ten einde kommersieel haalbare tegnologie te ontwikkel vir die ontginning van afvalprodukte. Byvoorbeeld, as gevolg van die komplekse, heterogene struktuur van lignosellulose, is die graad van solubilisering en die modifikasie en omskakeling van verskillende komponente nog onduidelik. Net so word die algehele anaerobiese afbreking van lignosellulose ook nog nie ten volle verstaan nie. In hierdie ondersoek het die klem geval op die bevordering van soliede anaerobiese digestie van lignosellulose afval vir omgewingsverbetering en die benutting van die afval. Die afbreking van lignosellulose in opvullingsterreine is eers eksperimenteel gesimuleer. Nadat die mikrobiese populasies en die afbrekingsprodukte gekarakteriseer is, is die bevordering van anaerobiese digestie deur die gebruik van geaktiveerde slyk bestudeer. Dit het asidogeniese fermentasie ingesluit, sowel as herwinning van die metanogeniese fase. Spesiale aandag is gegee aan die verdere verwerking van humus sure en humussuurbevattende legate wat in die digestiewe stelsel gegenereer is, aangesien die sure probleme veroorsaak het met die vertering van die lignosellulose. Met ultrasoniese straling is nagenoeg 50% van die lae-molekulêre massafraksie van die humussure ontbind in vlugtige vorm, maar die hoë-molekulêre massafraksie het geneig om in 'n kolloïdale vorm te aggregeer, wat slegs uit die stelsel verwyder kon word deur middel van ultrasonies ondersteunde adsorpsie op voorafgevormde aluminiumhidroksiedvlokkies. Dit is gevolg deur 'n ondersoek na die mikrobiese afbreking van humus sure en die toksisiteit van die sure ten opsigte van anaerobiese konsortia. Verdere eksperimentele werk is gedoen ten opsigte van die biologiese en abiologiese behandeling van lignosellulose in 'n opwaartsvloeiende anaerobiese slikkombersreaktor (OASK) gevoer met glukosesubstrate. Die humus sure kon gedeeltelik gehidroliseer en ontbind word deur die suurgistende konsortia van die granules in die OASK reactor. Ten slotte kan die vaste termofiliese-mesofiliese anaerobiese lignosellulose verteringslik ook gesien word as 'n humusryke higiëniese produk wat die vrugbaarheid en die waterhoudende vermoë van landbougrond kan verhoog, plante kan voed en kan funksioneer as bioabsorbeerder van swaarmetale in die omgewing.
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Anbalagan, Anbarasan. "Indigenous microalgae-activated sludge cultivation system for wastewater treatment." Licentiate thesis, Mälardalens högskola, Framtidens energi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-31543.
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The municipal wastewater is mainly composed of water containing anthropogenic wastes that are rich in nutrients such as carbon, nitrogen and phosphorous. The cost for biological treatment of wastewater is increasing globally due to the population growth in urban cities. In general, the activated sludge (AS) process is a biological nutrient removal process used in wastewater treatment plants (WWTPs). The AS is composed of different microorganisms in which bacteria play a crucial role in wastewater treatment (WWT). During the process, air is bubbled to supply oxygen and methanol is added to improve nitrogen removal, which is released as a gas. Phosphorous is removed in the expense of precipitation chemicals. Altogether, the current process requires electrical energy, precipitation chemicals, handling of excess sludge and it emits carbon dioxide (CO2) as a by-product. This process is still in practise in the WWTPs since 1914 although numerous modifications are implemented to meet the stringent regulations in the European Union and globally. Microalgae are microorganisms that perform photosynthesis like plants. They are green and reproduce fast using available nutrients (nitrogen and phosphorous) and CO2 from their environment in the presence of light. As a result of photosynthesis, oxygen is released as waste gas. The synthesised oxygen during this process can be implemented to support the AS bacteria that leads to the microalgae activated sludge (MAAS) process. The main advantage is combined removal of nutrients. The vision of the research is to implement the indigenous microalgae cultivation in activated sludge process to consume CO2 and recover the nutrients from wastewater. This study is performed to improve the understanding of the process such as: light utilisation, nutrient removal and recovery of the biomass from wastewater in closed photo-bioreactors. Photo-bioreactors are vessels where the cultivation is carried out in the presence of light. At first, the influence of the light spectrum on micro-algal cultivation is investigated for photosynthetic growth. This is followed by operational challenges of the microalgae cultivation during the AS process. The process is experimentally performed in the photo-bioreactors with different treatment time of the raw wastewater. The results showed that 2 - 6 days of treatment time can be used for reducing nutrients in wastewater if the process is optimised further. Also, nutrient ratio is analysed for the availability of the micro-algal growth. Furthermore, the biogas potential of MAAS showed a biogas yield of about 60-80% within 5 to 9 days. At last, the experimental verification of chemically precipitated wastewater showed limitation of phosphorous for micro-algal growth. Additionally, the optimal oxygen supply through light response is verified for photo-bioreactors. The outcome of this study shows that knowing the right conditions can lower the treatment time. By doing so, a stable nutrient removal and reduction of precipitation chemicals can be established as well as a better recovery of valuable nutrients as phosphorous and nitrogen.Avloppsvatten innehåller allt det ni spolar ner i avloppet, med höga halter av viktiga näringsämnen som fosfor, kväve och kol. Kostnaden för att rena avloppsvatten ökar i världen på grund av ökad urbanisering och ökade krav på reningen. Reningsprocessen domineras av aktivslamprocessen, i vilken mikroorganismer (främst bakterier) renar vattnet från kol och kväve medan det mesta av fosforn fälls ut med kemikalier. Processen är mycket energikrävande på grund av den stora mängden luft som pumpas in för att förse bakterierna med syre. Tillsammans utgör alla de här funktionerna en energi- och resurskrävande process som dessutom kräver tillskott av mer kol, oftast som ren alkohol, för att kvävereningen ska fungera. I den här avhandlingen har ett alternativ till konventionell, bakteriell avloppsvattenrening studerats; mikroalgbaserad aktivslamprocess (MAAS). Bakgrunden är att gröna mikroalger i likhet med växter utnyttjar fotosyntesen. Genom i fotosyntesen kan algerna snabbt föröka sig om det finns näringsämnen, ljus och koldioxid. Eftersom avloppsvattnet innehåller alla nödvändiga näringsämnen kan det räcka med att tillsätta koldioxid under rätt ljusförhållanden för att en livskraftig algkultur ska växa till. Algerna producerar även syre i processen som i sin tur kan användas av bakterierna i MAAS processen i en intressant symbios. Mest intressant är mikroalgbaserad vattenrening ur ett resursutvinningsperspektiv eftersom näringsämnena assimileras i algerna och därmed förblir i slammet och kan sedan utvinnas som en gödselprodukt. Målet med MAAS-forskningen har varit att använda koldioxid, näringsämnen och en algkultur från svenska förhållanden, i det här fallet Mälaren, för att bygga upp en effektiv kultur för vattenrening. Samtidigt vill vi i forskningen optimera processen utifrån hur mycket ljus som behöver tillföras, hur snabbt mikroorganismerna kan rena vattnet och vilka andra ämnen som kan störa processen. I den här avhandlingen har olika ljuskällor undersökts, med särskilt fokus på effektiva LED-lampor. Därefter har målet varit att optimera processen så att uppehållstiden, dvs den tid det tar för en viss volym vatten att renas, skulle kunna sänkas från 6 dagar (vilket anses vara internationell standard) till 4 eller till och med 2 dagars uppehållstid. Slutligen studerades effekterna av fällningskemikalier i mikroalgkulturen med slutsatsen att mikroalger blir begränsade av fällningskemikalier men att mikroalgerna däremot har goda förutsättningar att rena vattnet från betydande mängder fosfor och därmed minska mängderna fällningskemikalier som måste till sättas.
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McCarvil, James. "Bacterial interactions with metals in the activated sludge system." Thesis, Glasgow Caledonian University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377697.
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Franco, Martim Félix Bento. "MBR activated sludge filterability characterization in cross flow filtration." Master's thesis, FCT - UNL, 2009. http://hdl.handle.net/10362/2520.
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia do Ambiente, perfil SanitáriaThe reliability of MBR operation and its capability to produce favorable results as regards water treatment, in comparison with conventional activated sludge systems, makes this technology so promising. Regarding the influence of different cross flow velocities on sludge filterability in cross flow filtration, velocities above 1m/s (considered as high velocity in this research), showed the strongest correlations between the filterability of activated sludge and its respective fractionation compounds (suspended solids, colloids and solutes). However as the MBR treatment process is a physical chemical process involving filtration and biological treatment, it leads to the phenomena of fouling – resulting in membranes becoming obstructed, requiring more energy and physical chemical cleaning, thus increasing the additional associated costs. In this thesis, a framework analysis of MBR technology uses is undertaken and the current state of the art regarding this technology. This research included an important experimental component, with the Delft Filtration Characterization method (DFCm) developed by TU Delft (Evenblij et al., 2005) for activated sludge filterability measurements, developed by Delft University of Technology in the Netherlands. Activated sludge filterability was compared with subsequent laboratory analyses: chemical oxygen demand, total organic carbon, total suspended solids, volatile suspended solids and particle counts in 0.4-5.0μm range. The aim of these analyses was a fractionation of sludge samples in suspended solids, colloids and solute. The sludge samples were collected on MBR full-scale in Heenvliet Wastewater treatment plant (WWTP), also in the Netherlands, where the treatment process also includes a conventional activated sludge system (oxidation ditch activated sludge). The influence of different cross flow velocities on sludge filterability in cross flow filtration was performed, using in-situ monitoring of Heenvliet WWTP. The results obtained in this study relating to monitoring of Heenvliet WWTP, showed a strong correlation between the activated sludge characteristics and the filterability.
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Murthy, Sudhir N. "Bioflocculation: Implications for Activated Sludge Properties and Wastewater Treatment." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30647.
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Studies were conducted to determine the role of bioflocculation in the activated sludge unit processes. Laboratory and full-scale studies revealed that bioflocculation is important in determining settling, dewatering, effluent and digested sludge properties (activated sludge properties) and may be vital to the function of all processes related to the above properties. In these studies, it was shown that divalent cations such as calcium and magnesium improved activated sludge properties, whereas monovalent cations such as sodium, potassium and ammonium ions were detrimental to these properties. The divalent cations promoted bioflocculation through charge bridging mechanisms with negatively charged biopolymers (mainly protein and polysaccharide). It was found that oxidized iron plays a major role in bioflocculation and determination of activated sludge properties through surface interactions between iron and biopolymers. Oxidized iron was effective in removing colloidal biopolymers from solution in coagulation and conditioning studies. The research included experiments evaluating effects of potassium and ammonium ions on settling and dewatering properties; effects of magnesium on settling properties; effects of sodium, potassium, calcium and magnesium on effluent quality; effect of solids retention time on effluent quality; and evaluation of floc properties during aerobic and thermophilic digestion. A floc model is proposed in which calcium, magnesium and iron are important to bioflocculation and the functionality of aeration tanks, settling tanks, dewatering equipment and aerobic or anaerobic digesters. It is shown that activated sludge floc properties affect wastewater treatment efficiency.Ph. D.
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Moodley, Rajan. "External nitrification in biological nutrient removal activated sludge systems." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/9945.
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Includes bibliography.In conventional nitrification-denitrification biological excess phosphorous removal (NDBEPR) activated sludge systems, such as the UCT system for example, both nitrification and phosphorous uptake (P uptake) occur simultaneously in the, usually large, aerobic reactor. In the UCT system the nitrate load to the anoxic reactor is limited by the a-recycle (i.e. system constraint recycle from the aerobic to the anoxic reactor) and the internal aerobic nitrification performance. The latter process, is mediated by the nitrifiers having a slow growth rate of 0.45/d, governs the sludge age of the biological nutrient removal activated sludge (BNRAS) system and thus results in long (20 - 25 day) sludge ages and large aerobic mass fraction requirements to nitrify completely. However, if stable nitrification could be achieved outside the BNRAS external nitrification (EN) system then nitrification and the suspended solids sludge age become uncoupled allowing greater flexibility into the BNRAS system.
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Sötemann, Sven. "External nitrification in biological nutrient removal activated sludge systems." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5003.
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Summary in English.Bibliography: leaves 5.1-5.7.
Biological nutrient removal activated sludge (BNRAS) systems have become the preferred treatment system for advanced municipal wastewater treatment in South Africa. They have proven to be cost-effective systems that produce effluents of excellent quality that can be re-introduced to the receiving water bodies without a significant negative impact on the scarce surface water of South Africa. The widespread implementation of the BNRAS system has drawn attention to some of the weaknesses of the system, predominantly (i) the long sludge ages and resulting large biological reactor volumes required for nitrification, (ii) filamentous organism bulking of the sludge that develops in the system, (iii) treatment of the P rich waste sludge from the system and (iv) containment of the large mass of P in the sludge during a failure of the aeration in the system. In order to overcome the first two weaknesses of the system, it is proposed to separate the process of nitrification from the BNRAS mixed liquor and achieve nitrification externally to the BNRAS system.
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Steffens, Marc Alexander. "Advanced process control for nutrient removal activated sludge processes /." [St. Lucia, Qld.], 1997. http://library.uq.edu.au/screens/steffens.html.
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Wos, Melissa Louise. "Methods For Understanding Bacterial Metabolic Activity In Activated Sludge." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/367303.
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Biological wastewater treatment relies on the diverse and complex metabolic activities of bacteria to remove pollutants. Its success depends on the metabolic efficiency of the bacteria. Activated sludge models use parameters that attempt to depict bacterial growth and metabolic processes. However, current methods do not separate metabolic activity from growth and maintenance. As a result, activated sludge processes are misinterpreted or over-simplified. Alternative methods for gauging bacterial activity have been proposed and include the measurements of cellular derived compounds that relate specifically to energy cycling and include Nicotinamide Adenine Dinucleotide [NADH]. To date, NADH has been largely measured within activated sludge using commercial online fluorimeters with in situ probes. However, this current method provides a measure of the 'bulk' (raw) fluorescence within the system, resulting in difficulties when interpreting fluorescence data and poor sensitivity for detecting changes in intracellular [NADH]. This study has developed a more reliable method for estimating intracellular [NADH] and thus metabolic activity within activated sludge systems. Separating extracellular from intracellular [NADH] in samples was crucial because NADH was released and accumulates in the extracellular environment at a concentration of 200 ~M immediately following bacterial death or lysis. This concentration did not decline overtime. This not only caused high background fluorescence but also reduced the sensitivity of detection for changes in intracellular [NADH]. In particular, considerably higher [NADH] values to those from the extracellular suspensions were obtained following extraction of the intracellular material, suggesting that the cell membranes were not being penetrated by the excitable light source. Of the extraction procedures examined, filtration followed by extraction of the intracellular material with a hot Tris buffer was the most efficient and was recommended for accurate estimates of intracellular [NADH] in situ. In addition, standards were used to quantify NADH (moles per cell and/or unit volume) from unknown samples. The limits of detection were found to be 1.058 - 353 uM, whereas concentrations above 353 jAM self-quenched. Sample concentrations were always within these limits of detection. Hence, the sensitivity, reliability and experimental application of the original method was improved upon and able to be used for the direct measurement of microbial metabolic activity, something that has not been demonstrated before now. This study found that bacteria have between 106~ I 08 NADH molecules per cell depending on their metabolic state. A highly metabolically active bacterial cell had between 1O6~ tO7 NADH molecules, while a less active bacterial cell had between to7 -to8 NADH molecules. These measurements of metabolic activity were simultaneously monitored alongside other measures of bacterial growth, such as the incorporation of radiolabelled thymidine into DNA as a direct measure of DNA replication (new cell synthesis), the incorporation of radiolabelled leucine into protein as a direct measure of protein synthesis, oxygen uptake rates (OUR) as a direct measure of respiration, ATP as a measure of potential energy and dissolved organic carbon (DOC) as a measure of substrate assimilation. As OUR deceased, bacterial growth (using both the thymidine and leucine assays), specific [NADH] and specific [ATP] increased. High OUR and substrate oxidation rates simultaneous with low specific [NADH] indicated high rates of electron transport and thus efficient metabolic activity. Also, low OUR and substrate oxidation rates simultaneous with high specific [NADHI indicated inefficient rates of electron transport, therefore inhibiting oxidative phosphorylation (ATP production). A lack of oxygen as the terminal electron acceptor did not efficiently reoxidise NADH to NAD and resulted in an accumulation of NADH within the cell. Thus, a measure of low specific [NADHI was linked to the efficient rate of reoxidation of NADH to NAD* and reflects high metabolic efficiency. DNA and protein syntheses were coupled following substrate enrichment (glucose or acetate), indicating that bacteria were in balanced growth. However, DNA and protein syntheses became uncoupled once substrate was depleted, indicating unbalanced growth. An average Leu:TdR ratio of 7.4 was determined for activated sludge and was comparable to values published from marine systems. This ratio increased during log growth phase and decreased during stationary growth phases. Specific growth rates determined using the [3HITdR and [3H]Leu assay yielded values ranging from 2 - 10.5 d' and from 2.5 - 6 d1, respectively and were comparable to published values. Changes in OUR, NADH, ATE', DNA replication and protein synthesis were statistically ordinated using multidimensional scaling, and changes (in magnitude and direction) in bacterial metabolic activity were observed. Such methods enable the tracing of where bacteria divert their energies, such as to growth or maintenance and thus provide a greater understanding of bacterial behaviour in activated sludge. While studying anoxic and anaerobic conditions were beyond the scope of this work, the use of such methods to monitor bacterial metabolic activity under such conditions is warranted.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environmental Engineering
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Luque, Jackeline. "Exocellular polymeric substances, bioflocculation and sludge settling properties in a combined anaerobic/activated sludge process." ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,238.
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Dissertation (Ph. D.)--University of New Orleans, 2005.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering and Applied Science"--Dissertation t.p. Vita. Includes bibliographical references.
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Graham, Brian Robert. "Comparison of powdered activated carbon and activated sludge treatment of a kraft pulp mill wastewater." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10257.
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The Powdered Activated Carbon Treatment$\rm\sp{TM}$ (PACT$\rm\sp{TM})$ process consists of powdered activated carbon addition to the activated sludge treatment process. Objectives were (1) to compare treatment of kraft pulp mill wastewater using activated sludge versus PACT$\rm\sp{TM},$ by measuring toxicity, organic load, adsorbable organic halides (AOX) and metals and (2) to assess how three operating conditions: (1) carbon dose; (2) hydraulic retention time; (3) solids retention time, affected performance. Findings were: (1) Lengthy hydraulic retention times are unnecessary. Short hydraulic retention times (4 h) provide adequate treatment. (2) Activated sludge treatment alone removes most biochemical oxygen demand, PACT$\rm\sp{TM}$ offers no improvement. PACT$\rm\sp{TM}$ improves removal of soluble chemical oxygen demand. PACT$\rm\sp{TM}$ improves removal of AOX. Powdered activated carbon dose is the sole determinant of this increased removal. (3) Activated sludge treatment alone removes Microtox$\rm\sp{TM}$ toxicity. PACT$\rm\sp{TM}$ slightly improves treatment of highly toxic wastewaters. Significant chronic toxicity towards Ceriodaphnia remains in effluents from both activated sludge and PACT$\rm\sp{TM}.$ Both treatments remove toxicity to Ceriodaphnia, but PACT$\rm\sp{TM}$ effluents are more toxic. Powdered activated carbon alone exhibits toxicity to Ceriodaphnia. (4) The effect of PACT$\rm\sp{TM}$ on removal of metals is inconclusive. (5) PACT$\rm\sp{TM}$ treatment of kraft mill wastewater would be very expensive. (6) PACT$\rm\sp{TM}$ has limited benefits over activated sludge for the treatment of kraft mill wastewater, therefore PACT$\rm\sp{TM}$ is not recommended for treatment of kraft mill wastewater.
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Cardete, García Mª Alicia. "Implementation of a selector for sludge settling enhancement in an activated sludge system treating petrochemical wastewater." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/667866.
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Due to the recent approval of the Best Available Techniques Reference Document for Wastewater Treatment in the Chemical Sector (Decision (UE) 2016/902), the European industry is urged to improve the wastewater treatments, in order to attain more stringent regulations. Particularly, petrochemical activated sludge systems focused on organic matter removal must face two frequent issues, which difficult sludge settling: i) Development of filamentous bulking due to low food-to-microorganism (F/M) ratio in the biological reactor ii) Unintended biological nitrification, which leads to denitrification in the clarifier. These tendencies were confirmed in a pilot petrochemical continuous stirred tank reactor (500 L), where sludge volumetric index (SVI) values of 350 mL g-1 were obtained. Nitrification was studied with an experimental petrochemical bench-scale bioreactor (1L), which provided concentrations up to 350 mg NOx--N L-1.
To overcome the filamentous bulking, a one-compartment selector was implemented in the pilot activated sludge system. The selector could be operated as anoxic or aerobic. Both configurations succeeded to solve the excessive proliferation of filaments with average SVI values below 75 mL g-1, provided dissolved oxygen concentrations higher than 2 mg L-1 were guaranteed in the main reactor. However, the aerobic selector showed the more robust and consistent performance, aiming to its full-scale implementation. Its optimum design parameters were determined at hydraulic retention time of 30 minutes and F/M of 35 g sCOD g-1 VSS d-1. Its performance improved with the biodegradability of the wastewaters supplied in the range of 10 to 50 g BOD g-1VSS d-1. Otherwise, the selector was unable to enhance sludge settling when being provided with high concentrations of particulate matter (up from 65 g tCOD g-1 VSS d-1). Nevertheless, the inclusion of the aerobic selector doubled the nitrification rates in the activated sludge system. Since conventional methodologies to limit nitrification may not be convenient for existing installations due to process or site constraints, a new strategy has been bench-scale developed. Two petrochemical bioreactors have been supplied with cost-effective concentrations of 0.4 and 0.9 mg g-1VSS d-1 of folic acid in comparison to a control. Afterwards, the vitamin supply has been stopped in order to
assess about habituation effects. Despite both doses have succeeded to control nitrification, the addition of folic acid has also affected the operational parameters of the biological system. The supply of the lower vitamin concentration provided a reduction on nitrification rates of 93.6% and improved the sludge volumetric index compared to control (17.4 in front of 67.3 mL g-1). However, its full-scale feasibility is conditioned to the availability of spare aeration capacity, since oxygen demand increased 85.7%, probably due to an older sludge age (71.4% reduction in observed sludge yield). Reductions up to 97.1% in nitrification rates were obtained during and 60 days after the dosage of the higher vitamin concentration. Despite other advantages, such as increasing the organic matter removal efficiency (60.0%) and reducing oxygen demand (14.7%) relative to control, the high dosed reactor exhibited a worse sludge settling (93.1 mL g-1) and more sludge production (57.1% increase in observed sludge yield). These results suggest new dosing alternatives, such as supplying a discontinuous folic acid concentration of 0.9 mg g-1VSS d-1.
To conclude, this manuscript provides industrial engineers with guidelines to upgrade their existing wastewater treatments. Although the experimentation has been conducted with petrochemical effluents, the methodology and conclusions could be extrapolated to other industrial sectors with similar characterization of wastewater. With regard to future steps, this research sets the basis for the development of the action mechanism for nitrogen heterocyclic compounds, as nitrification inhibitors, which is of interest for the wastewater and the agricultural field.Con la aprobación de la nueva versión del BREF de aguas residuales, la industria química europea está obligada a mejorar sus procesos de tratamiento de agua para adaptarse a especificaciones de vertido más restrictivas. Particularmente, los sistemas de fangos activos petroquímicos focalizados en la degradación de materia orgánica deben afrontar dos limitaciones frecuentes que dificultan la decantación del lodo: fuerte tendencia al bulking filamentoso por baja razón alimento-biomasa (F/M) y nitrificación biológica no deseada. Ensayos piloto con efluentes petroquímicos han demostrado que la inclusión de un selector aerobio en el sistema de fangos activos permite superar el bulking filamentoso, obteniendo siempre valores de índice volumétrico de fangos inferiores a 75 mL g-1. Los parámetros de diseño óptimos para el selector son un tiempo de residencia de 30 minutos y una razón F/M de 35 g DQO g-1 VSS d-1. Se debe alimentar al selector los efluentes más biodegradables y con el mínimo contenido en materia orgánica particulada. Sin embargo, con la implementación del selector, la nitrificación se ha duplicado. Puesto que las técnicas convencionales de control de nitrificación no resultan adecuadas por limitaciones de proceso y de implementación, se ha desarrollado como alternativa, la dosificación de ácido fólico al reactor biológico. En ensayos de laboratorio con un reactor petroquímico, dosis continuas de 0,4 y 0,9 g g-1 VSS d-1 de vitamina han permitido limitar la nitrificación a concentraciones inferiores a 10 mg NOx—N L-1 sin aportar toxicidad al efluente. La alta concentración, incluso ha mantenido este efecto hasta 60 días después de cortar la dosificación de vitamina. Sin embargo, el ácido fólico ha modificado los parámetros operativos del sistema biológico. La concentración baja ha aumentado el consumo de oxígeno (85,7%). La concentración alta ha aumentado la eficiencia en degradación de materia orgánica (60,0%), la producción de biomasa (57,1%) y ha empeorado la decantación del lodo (93±29 mL g-1). Estos resultados aconsejan ensayar otras estrategias posológicas, tales como dosis discontinuas de 0,9 g g-1 VSS d-1. Esta investigación proporciona las bases para un desarrollo futuro del mecanismo de acción de las moléculas heterocíclicas nitrogenadas, como inhibidores de la nitrificación.
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An, Kyoung Jin. "Reduction of excess sludge in an oxic-settling-anaerobic (OSA) system : a modified activated sludge process /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20AN.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 188-201). Also available in electronic version. Access restricted to campus users.
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Sam-Soon, Paul Alan Li Nai Sing. "Pelletization in the upflow anaerobic sludge bed (UASB) reactor." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/17151.
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Includes bibliography.This investigation was prompted by a study into the feasibility of treating an apple juicing waste water in an upflow anaerobic sludge bed (UASB) reactor system. Past experience with this system suggested that a pelletized sludge would be produced due to the nature of the waste water. This indeed was observed but the system exhibited an unusual feature, a high removal of nitrogen far in excess of that normally found in normal anaerobic processes. This observation stimulated a far reaching investigation into, the behaviour of the pelletized sludge bed, the causes giving rise to pelletization, a biochemical model explaining pellet formation, verification of the biochemical model, criteria for pellet formation, pH control in the pelletized sludge bed, and a kinetic model for the UASB process.
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Saikaly, Pascal E. "Ecological approach to mitigate toxic shocks in activated sludge systems." Connect to resource online, 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1125670988.
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