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1
Kim, Jinho. "Floc properties in stirred suspensions." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268458.
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2
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.<br>Master of Science
3
Selomulya, Cordelia Chemical Engineering & Industrial Chemistry UNSW. "The Effect of Shear on Flocculation and Floc Size/Structure." Awarded by:University of New South Wales. Chemical Engineering and Industrial Chemistry, 2002. http://handle.unsw.edu.au/1959.4/18226.
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The effect of shear on the evolution of floc properties was investigated to analyse the flocculation mechanisms. Little fundamental attention has been given to the shear influence that often creates compact aggregates, while the floc characteristics might differ in other aggregating conditions. It is thus crucial to understand how flocs evolve to steady state, if their properties are to be 'tailored' to suit subsequent solids-liquid separation processes. In this work, flocculation of monodisperse latex particles of various sizes (60, 380, and 810 nm diameter) via electrolyte addition was carried out in a couette-flow and also in shear fields generated by an axial-flow impeller (Fluid foil A310) and a radial-flow impeller (Rushton R100) in standard mixing tanks. A small-angle light scattering technique was used to acquire information regarding the time variation of floc properties in a non-intrusive manner. The structure was quantified by a measure of fractal dimension, signifying the degree of floc compactness. Estimates of the average floc mass were also obtained from the aggregate scattering patterns. By monitoring the changes in floc structure and mass, corresponding to the size evolution; mechanisms of floc formation, fragmentation, and restructuring were identified. Aggregates of 60 and 380 nm particles were observed to grew larger initially, before decreasing to their equilibrium sizes at moderate shear rates (32 - 100 s-1) in a homogeneous shear environment. Floc restructuring at large length scales occurred extensively, and was responsible for the drop in size, particularly at the early stage of the process. Aggregates of 810 nm particles did not, however, display this behaviour. Flocs of larger primary particles were presumably susceptible to breakage rather than deformation, as they were weaker under comparable conditions. Denser aggregates were found when restructuring transpired, while comparatively tenuous flocs were observed when formation and breakage kinetics were the governing mechanisms. The disparity in floc behaviour at higher shear rates (246 s-1 - 330 s-1) was less apparent. The intense hydrodynamic stresses in those instances inevitably caused fragmentation, regardless of the intrinsic particle properties; hence the observed floc compaction was the product of break-up and re-aggregation. A population balance model, incorporating variation in floc structure, displayed comparable trends in size evolution; verifying that restructuring indeed took an important role under certain flocculation conditions. Similar phenomena were likewise observed with the flocculation in stirred tanks. The results reinforced findings in literature; that while circulation time controlled the process kinetics; the floc size was determined by the turbulent stresses. In addition, the maximum shear levels also influenced the floc structures, with denser aggregates produced in a shear field generated using the radial-flow impeller at equivalent energy dissipation per-unit mass. A correlation between non-dimensional floc factor that embodied the aggregate size and structure, and aggregation factor comprising the significant parameters from flocculation conditions, was proposed. The proposed relationship takes into account aspects such as the aggregate structure, interparticle forces, and particle concentration that are often overlooked in existing relationships, which usually only relate the maximum floc size to the applied energy dissipation rate. It thus provides an improved manner of presenting general flocculation data, as well as a means to predict floc properties produced under a specific aggregation condition. Future studies with increasingly complex systems that resemble real conditions are recommended in order to establish a practical understanding of the flocculation mechanisms, for the purpose of optimising the aggregate properties.
4
Amornraksa, Suksun. "Development of magnetic floc technology for water treatment." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405033.
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McCabe, Jeremy Charles. "Observations of estuarine turbulence and floc size variations." Thesis, University of Plymouth, 1991. http://hdl.handle.net/10026.1/1790.
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Laboratory studies show that turbulence controls the size of flocs by disrupting those flocs which exceed a critical diameter. Estuarine floc sizes have been shown to vary with the spring/neap cycle and turbulence has been suggested as the mechanism. A survey of the tidal variations of cohesive sediment floc size distributions and turbulence parameters has been undertaken in the Tamar estuary in south-west Britain. In-situ particle size distributions have been obtained using a 'marinised' version of the 'Malvern' laser diffraction sizing system. Turbulent current speeds were obtained using 10 cm diameter annular electromagnetic current meters. Velocity data is analysed using the inertial dissipation method to provide turbulent dissipation rates. Turbulence and size data, along with profiles of current, salinity, temperature and suspended solids concentration, record the passage of turbidity maximum and salt intrusion over four complete tidal cycles. Time series of observed particle size distributions vary smoothly over timescales of about one hour and these variations are linked to the flow conditions. Eight subsections of the tidal cycle were selected over which size distributions and flow conditions were slowly varying and the size distributions were time averaged over these subsections, and the resulting distributions compared. Size distributions in the turbidity maximum are strongly influenced by the mean current speed and this is found to be due to the different resuspension characteristics of newly formed aggregates and consolidated primary particles. Distributions are less dependent on tidal range at other stages during the tidal cycle. The size dependence of settling velocities strongly influences the size distribution of particles reaching the bed during the final stages of erosion of the salt intrusion, when the salt/fresh interface descends at a rate less than the settling velocity of large flocs but greater than that of small particles. This tends to sharpen the downstream edge of the turbidity maximum and preferentially retain floc aggregates in the upper reaches of the estuary.
6
Åkesson, Krister. "Floc behaviour in a twin-wire blade pressure pulse /." Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-386.
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7
Jarvis, Peter. "The impact of natural organic matter on floc structure." Thesis, Cranfield University, 2004. http://dspace.lib.cranfield.ac.uk/handle/1826/4559.
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The removal of natural organic matter (NOM) at water treatment works (WTW) is essential in order to prevent toxic compounds forming during subsequent disinfection. Coagulation and flocculation processes remain the most common way of removing NOM. The properties of the resulting flocs that form are fundamental to the efficient removal of organic material. Periods of elevated NOM loads at WTW can lead to operational problems as a result of the deterioration in floc structural quality. Assessment of floc physical characteristics can therefore be a crucial tool in order to determine and predict solid-liquid removal performance at WTW. Here the growth, size, breakage, strength, re-growth, fractal dimension and settling velocity were measured for flocs formed from a NOM rich water source. NOM floc structural characteristics were measured and evaluated over a one year period in order to monitor the seasonal variation in floc structure. The results showed that a significant improvement in floc size and strength was seen during autumn and summer months. It was subsequently shown that as the organic fraction in the floc increases the floc size, settling velocity and fractal dimension all decrease. A model was proposed showing how these changes were dependent upon the adsorption of NOM onto primary particle surfaces. A range of different chemical coagulant treatment options were applied for NOM removal and the resulting floc structure compared. Considering both floc structure and optimum NOM removal the treatment systems were of the following order (best to worst): MIEX® + Fe > Fe > Fe + polymer > Al > polyDADMAC. NOM floc re-growth was shown to be limited for all the treatment systems investigated. The practical implications of the results were: (1) The requirement for careful coagulant dosing or order to achieve optimum floc characteristics. (2) The use of a pre-treatment anionic ion-exchange stage prior to coagulation. (3) A comparison of alum and ferric based coagulants suggested the ferric coagulants gave better floc structure and improved NOM removal rates.
8
Mallon, James M. "Floc structure and the improvement of chemical water cleaning." Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324839.
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Collier, Nicholas Charles. "The encapsulation of iron hydroxide floc in composite cement." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434632.
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Baghaei-Yazdi, Nader. "Simulation of floc blanket clarification using granular fluidised beds." Thesis, University College London (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394585.
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Al-Ani, S. H. "Development of a vibratory system for evaluating floc strength." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382279.
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Medina, Rodríguez Luisa Marcela. "Floc formation in wastewater treatment systems using algal bacterial symbiosis /." Hamburg : Techn. Univ. Hamburg-Harburg, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015584416&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Khan, Konika Moushumi Chemical Sciences & Engineering Faculty of Engineering UNSW. "The effect of floc microstructure and shear on dewatering processes." Awarded by:University of New South Wales. Chemical Sciences & Engineering, 2007. http://handle.unsw.edu.au/1959.4/40547.
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This work investigated the effect of floc microstructure (size and fractal structure) and shear forces on dewatering processes, which are crucial for environmental and economical aspects in many industries. Due to limitations inherent In experimental investigations, a numerical code using the discrete element method and including some novel force models (polymer bridging force, elastic bending moment and a modified concept of rolling friction torque) was developed to simulate the consolidation behavior of flocculated systems. The code showed good agreement with experimental results. The elastic behavior of aggregates is known to depend on the backbone structure (stress bearing structure of the aggregate). However, there is little known about backbone structure. It was found that backbone represents a fractal structure with a fractal dimension value close to 1 and increasing with increase of aggregate mass fractal dimension. The dewatering process was characterized by compressive and hindered settling behavior. The numerical study of compressive rheology with different aggregate microstructure showed that the compaction results from a reduction of the correlation length rather than increase in fractal dimension. The compressive behavior is consistent with theoretical models at higher compressive stresses but is not well described at low compressive stresses. A semi- empirical model is presented describing the compressive rheology in both regions via a correction factor derived using dimensional analysis. The hindered settling behavior was in good agreement with the theoretical model based on the assumption of self similar structure. The investigation revealed that shear effect is not due entirely to hydrodynamics and can arise from the particle bonding mechanism alone. The study showed that low shear increases compressibility but high shear is detrimental. At low shear, bond bending at local voids results in solid densification. High shear increases kinetic energy and kinetic repulsion of the particles. The effect of shear is analogous to the anomalous behavior of the water density- temperature function. At low temperature bond breakage increases the density and at high temperature thermal expansion decreases the density. The investigation showed that shear increases the permeability due to bending of the structure in the shear direction, resulting in large pores.
14
Bridgeman, Jonathan Matthew. "Investigating the relationship between shear and floc fate using CFD." Thesis, Cranfield University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438443.
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15
Wu, Jun. "Characterization of activated sludge processes by particle and floc analysis." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/34158.
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Monitoring and control of activated sludge mostly use non-microbial specific parameters (e.g. SS, COD, BOD etc.). This thesis suggests they are no longer precise enough to give adequate reliability of the removal of N and P to meet the new standards. Basic theory points to the importance of mass transfer, diffusion and biochemical reaction rates in determining microbial morphology and therefore settlement. These phenomena are influenced by particle characteristics both of the feed and the floc itself. The thesis researches particle and floc characteristics and correlates their variability with the changes in waste characteristics, biodegradability, settleability, plant design (nitrifying, non-nitrifying, biological phosphorus removal and MBR) and effluent quality.
16
Vahedi, Arman. "Predicting the Settling Velocity of Lime Softening Flocs using Fractal Geometry." Elsevier, 2010. http://hdl.handle.net/1993/4953.
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Stokes’ law that is traditionally used for modeling the sedimentation of flocs, incorrectly assumes that the floc is solid and spherical. Consequently the settling rates of flocs cannot be estimated using the Stokes law.
The application of fractal dimensions to study the internal structure and settling of flocs formed in lime softening process was investigated. An optical microscope with motorized stage was used to measure the fractal dimensions of lime softening flocs directly on their images in 2 and 3D space. The fractal dimensions of the lime softening flocs were 1.15-1.27 for floc boundary, 1.49-1.90 for cross-sectional area and 2.55-2.99 for floc volume. Free settling tests were used for indirect determination of 3D fractal dimension. The measured settling velocity of flocs ranged from 0.1 to 7.1 mm/s (average: 2.37 mm/s) for the flocs with equivalent diameters from 10µm to 260µm (average: 124 µm).
Floc settling model incorporating variable floc fractal dimensions as well as variable primary particle size was found to describe the settling velocity of large (>60 µm) lime softening flocs better than Stokes’ law. Settling velocities of smaller flocs (<60 µm) could still be quite well predicted by the Stokes’ law. The variation of fractal dimensions with lime floc size in this study indicated that two mechanisms are involved in the formation of these flocs: cluster-cluster aggregation for small flocs (>60 µm) and diffusion-limited aggregation for large flocs (<60 µm). Therefore, the relationship between the floc fractal dimension and floc size appears to be determined by floc aggregation mechanisms.
The settling velocity of lime softening flocs was also modeled by a general model that assumes multiple normally distributed fractal dimensions for each floc size. The settling velocities were in the range of 0-10mm/s and in good agreement with measured settling velocities (0.1-7.1mm/s). The Stokes’ law overestimates the settling velocity of lime flocs. It seems that the settling velocity of flocs is mainly controlled by aggregation mechanisms and forming large floc does not guarantee improved sedimentation.
The multifractal analysis of lime softening flocs showed that these aggregates are multifractal and a spectrum of fractal dimensions is required to describe the structure of an individual floc.
17
Mawhinney, Heather Joan. "The improvement of effluent and water treatment by chemical floc modification." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343019.
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Arundel, Catherine E. "The role of floc density measurements in analyzing sludge dewatering characteristics." Thesis, Virginia Tech, 1986. http://hdl.handle.net/10919/41559.
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<p>Floc density measurements may play a significant
role in analyzing sludge dewatering characteristics. A
laboratory technique was developed to measure this property by means of isopycnic centrifugation. Four
laboratory sludges were subjected to a series of
dewatering tests: gravity thickening, centrifugation,
vacuum filtration, and highâ pressure dewatering. Each
sludge was analyzed for changing macro-and
microâ properties during increasing stages of dewatering.
It was concluded that sludge thickening rates are
influenced by aggregate volume fractions, sludge
density, suspension porosity, and the total surface area
occupied by sludge aggregates. The extent of mechanical
dewatering is impacted by similar parameters; namely,
floc volume fractions, sludge density, cake porosity, and the total surface area occupied by sludge floc.</p>
<p>
By interpreting the laboratory data, a model was
formulated to describe changes in water distribution
during the dewatering of sludges. This model includes a
speculative view of the qualification and quantification
of water-types.</p><br>Master of Science
19
Park, Chang Shin. "A dynamic behavior of pulp floc and fibers in the papermaking process." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/7044.
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Sood, Payal Lalit. "Grammage Probabality Distributions to Predict the Source of Floc Formation in Paper." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1249685634.
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Balls, Margaret. "Relationships between floc properties and NOM removal using a moorland water source." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1417138/.
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Natural organic matter, or NOM presents a treatment challenge to the conventional water treatment process and has been associated with the formation of disinfection by-products (DBP’s) such as Tri-halomethanes (THM’s) if not removed prior to the disinfection stage. Poor removal of NOM is also thought to lead to filter performance problems such as turbidity or particle count breakthrough, which represents an increased risk of passage of Cryptosporidium into the treated water. Understanding the complex nature of NOM floc and how its physico-chemical properties relate to the coagulation matrix within the water treatment process is therefore key to optimising NOM removal. This forms the basis of the study which was carried out entirely using a natural raw moorland source water, which is preferable over synthetic kaolin based systems. The experimental programme encompassed both bench-scale and pilot-scale tests, and investigated the effect of changes to a number of variables such as coagulant type, coagulation pH and Fe:DOC ratio on floc physico-chemical properties. The approach taken in this work, of monitoring NOM removal alongside floc properties obtained from the optical flocculation monitor revealed some key trends. Firstly under equivalent shear conditions the coagulant dose almost always correlated with the steady-state maximum floc size, and influenced the flocculation rate. Generally the ferric based systems with the largest and fastest forming floc correlated with the best NOM removal, but when the applied Fe:DOC range was narrow and within an optimal range it was difficult to pin-point the best dose. The organic coagulants polyDADMAC and Zetag 64 formed larger, amd more reversible floc than the ferric based systems but with poor NOM removal. Secondly under equivalent shear conditions the larger flocs exhibited the least resistance to breakage, regardless of the coagulant system. Finally with regard to floc physico-chemical properties and filter performance, some key trends were revealed. Zeta potential influenced both NOM removal and the filtered water quality with considerable improvement noted as the charge tended towards 0 mV, and poor performance in the form of breakthrough as the charge decreased to <-10 mV or >4 mV. Flocculant dosing prior to filtration increased floc reformation and prevented breakthrough when charge destabilisation was sub-optimal, and could prove a useful strategy to employ when experiencing challenging winter conditions.
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Kuprenas, Rachel Leah. "Improvements to the Modeling of Average Floc Size in Turbulent Suspensions of Mud." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83764.
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The accuracy of sediment transport models depends on identifying an appropriate sediment settling velocity. Determining this value for mud suspensions can be difficult because cohesive mud particles can aggregate, forming flocs whose sizes are a function of hydrodynamic and physiochemical conditions of the suspension. Here we present a new model refining the predicted floc size based on hydrodynamic conditions and inherited floc sizes, as well as on the salinity of the fluid environment. The improvements come from modifications made to the Winterwerp (1998) (W98) model. These improvements include: limiting floc size to the Kolmogorov microscale and including an initial salinity dependence. Limiting floc size in this way brings the model predictions more in line with flocculation theory and experimental observations. The salinity dependence was introduced based on a preliminary set of experiments that were conducted to examine floc growth rate and equilibrium size under different salinity conditions. In these experiments, increasing salinity from 2.5 to 10 PSU did not affect equilibrium floc size. However, the increases in salinity did result in longer times to equilibrium and an apparent increase in floc density or fractal dimension. The modified W98 model allows calibrated aggregation and breakup coefficients obtained under one set of concentration values (for both sediment and salinity) to be used to predict floc size under other concentration conditions. Comparing the modified W98 model with laboratory data shows more accurate predictive values, indicating that the modified W98 equation is a promising tool for incorporation into larger sediment transport models.<br>Master of Science
23
Ahranjani, Nayrah Khandani. "Modelling of a Suspended Floc in Wastewater Treatment Systems using Object-Oriented Programming." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519487.
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Dishman, C. Michael. "Floc density measurement and the effects of microproperty variations on sludge dewatering characteristics." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43847.
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Muller, Christopher Dustin. "Shear Forces, Floc Structure and their Impact on Anaerobic Digestion and Biosolids Stability." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28768.
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This study was conducted to address the controlling factors of biosolids stability as they relate to mesophilic anaerobic digestion, dewatering processes and digestion enhancement by wet sludge disintegration technologies. The working hypothesis of this study is that digestion performance; nuisance odor generation and the degree of digestion enhancement by wet sludge disintegration are directly related to anaerobic floc structure and its interaction with shearing forces. Mesophilic digestion was studied in two modes of operation, convention high rate and internal recycle mode to enhanced digestion using a wet sludge disintegration device. The internal recycle system operated on the premise that stabilized sludge would be removed from the digester disintegrated, either by mechanical shear or ultrasonic disintegration for this study, and returned it for to the digester further for further stabilization. Both benchscale and full-scale demonstrations found this mode of digestion enhancement to be effective for mechanical shear and ultrasonic disintegration.
It was also determined that volatile solids destruction in both conventional and enhanced mesophilic anaerobic digesters can be reasonably predicted by the concentration of cations in the sludge being treated. It was found that depending on the disintegration device used to enhance digestion performance was influenced by different cation associated fractions of the sludge floc.
Along with the improvement of digester performance, overall biosolids stability was investigated through of volatile organic sulfur emissions from dewatered biosolids. In doing so, a method to mimic high solids centrifugation in the laboratory was developed. The centrifugation method identified three major factors that contribute to the generation of odors from biosolids: shear, polymer dose, and cake dryness. The inclusion of shearings suggest that one means of reducing odors from biosolids generated by centrifugation is to use a shear enhanced digestion technology to degrade odor precursors, such as amino acids, within the digester prior to dewatering. Furthermore, the mechanical shearing within a digester is thought to be similar to that of mechanical shear enhanced digestion; therefore, the floc properties that control the digestion process would control observed odor generation.<br>Ph. D.
26
Kajaman, Aboajela. "Modelling and control of an activated sludge process using ASM2d and taking into account sludge floc distribution effects." Thesis, De Montfort University, 2015. http://hdl.handle.net/2086/11422.
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To reduce energy consumption, and to achieve the desired denitrification, the activated sludge process sometimes needs to operate at low dissolved oxygen concentrations. The ASM2d model describes the activated sludge process, if nitrification and denitrification occur during different phases in a sequencing batch reactor (SBR). Despite the widespread study of enhanced biological phosphorous removal, comprehensive sludge floc distribution model remains lacking that would better describe this process. Consequently, the integrated system model has been developed to understand the impact of floc at low DO concentrations, and during the process of biological nitrogen and phosphorous removal. In a wastewater treatment plant used in this study, the dissolved oxygen was controlled at a low concentration, 1.7〖gO_2 m〗^(-3), and the dispersion coefficient into the floc was found to be 〖D=1.2×10〗^(-4) m^2/day. Introduction of a number of effectiveness factors contributed to the development of the ASM2d model described herein. This developed model could be valuable for predicting process behaviours applicable under various configurations. Moreover, parameters and effectiveness factors for the model could be calibrated using a genetic algorithm approach. Optimisation was then achieved by controlling the solids retention time during the activated sludge process.
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Lee, Boon Chong. "The influence of nutrients on floc physicochemical properties and structure in activated sludge processes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28822.pdf.
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Di, Domizio Thomas John. "Treatment of Colorado River water with ozone, ferric chloride and Cat-Floc T-2." Thesis, The University of Arizona, 1990. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1990_607_sip1_w.pdf&type=application/pdf.
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Di, Domizio Thomas John 1963. "Treatment of Colorado River water with ozone, ferric chloride and Cat-Floc T-2." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/192043.
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Colorado River water (CRW) is a traditionally high quality source but it will require treatment for turbidity removal and disinfection in order to meet existing and future water treatment regulations. In this research, a treatment process consisting of preozonation followed by chemical coagulation, flocculation, and direct filtration was investigated. The effects of ozone, ferric chloride, and Cat-Floc T-2 doses on turbidity, UV absorbance at 254 nm, and total organic carbon (TOC) removal were statistically evaluated in order to determine the optimum chemical combinations required to achieve the treatment objectives. The ozone dose employed had the most significant impact (>99% confidence level) on turbidity removal. At a 99% confidence level, ozone and Cat-Floc T-2 were found to be statistically significant in reducing UV absorbance. There were no significant decreases in TOC observed with any of the treatment combinations studied. This was attributed to the low ozone doses employed. A second part of this research involved a study on the effects of the treatment chemicals on CRW after kaolinite had been added to artificially increase its turbidity.
30
Muller, Christopher Dustin. "High-Intensity Shear as a Wet Sludge Disintegration Technology and a Mechanism for Floc Structure Analysis." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33650.
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By shearing activated sludge using a high shear rotor stator device, bioavailable proteinaceous material can be produced. Operation at elevated temperatures, serves to increase the amount of material that is rendered soluble (<0.45 um) and biodegradable. The storage of sludge under anoxic condition prior to shearing does not appear to enhance solublization of solids, though deflocculation and deterioration of dewaterablility was observed. Anaerobic digestibility appears to be enhanced by the addition of a high shear as shown by increases in gas production and volatile solids destruction. The dewatering properties of activated sludge, measured by capillary suction time, deteriorated with the addition of sheared solids, but reaeration resulted in near complete recovery.
The role of iron and iron chemistry plays a critical role in the activated sludge. Iron apparently selectively removes protein, in particular material ranging in the 1.5 um to 30K size range. The addition of ferric iron was found to increase SVI and decrease zone-settling velocity, when added to reactors with mechanically disintegrated sludges. Similar trends were not observed in reactors dosed with ferrous iron. Preliminary results suggest that the ferric/ferrous redox chemistry may serve to enhance floc structure, as observed by increased settling velocity and shear resistance for sludges dosed with ferrous sulfate.<br>Master of Science
31
Koivuranta, E. (Elisa). "Optical monitoring of flocs and filaments in the activated sludge process." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526211794.
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Abstract Flocculation plays a critical role in the activated sludge process, where flocs are removed by settling and where unsatisfactory flocculation is resulting in poor effluent quality. Control and operation of the process is also challenging as it is sensitive to external and internal disturbances. Furthermore, stricter environmental demands are also being placed on wastewater treatment and discharge quality thus solutions are needed to improve the current systems. A novel optical monitoring method employing a tube flow and a CCD camera was developed to characterize the flocs and filaments of the sludge, and the method was tested on samples from full-scale activated sludge plants. An online device operating on the same principle was also developed and this was tested over a period of eight months at municipal wastewater treatment plant. Optical monitoring was employed in the laboratory to study the breakage of activated sludge flocs. Based on the image analysis data, in the industrial plant the major breakage process was large-scale fragmentation. In the two municipal plants, it was surface erosion. The flocs had more filaments and were more irregular in shape in the industrial plant, which could be the reason for the large-scale fragmentation. The effect of floc morphology on the effluent clarity of the activated sludge process was studied in the industrial and municipal activated sludge plants by optical monitoring over periods of three months and eight months, respectively. The changes in floc morphology took place slowly in both plants. Four major factors that correlated with the purification results were the size and shape of the flocs and the quantities of small particles and filaments. The image analysis results suggested that the settling problem that occurred during the test periods in the industrial plant was caused by dispersed growth, whereas that in the municipal plant was caused by filamentous bulking. In conclusion, it is possible to use the developed method online in order to analyse the state of flocculation. Thus the method could be useful when developing online monitoring applications for quantifying floc characteristics and for diagnosing the causes of settling problems in the wastewater treatment plants<br>Tiivistelmä Aktiivilieteprosessissa flokkulaatiolla on merkittävä rooli, sillä muodostuneet flokit poistetaan prosessista laskeutuksen avulla. Siten huono flokkulaatio johtaa puhdistetun jäteveden kiintoainemäärän lisääntymiseen. Prosessin säätö ja operointi on kuitenkin hankalaa, sillä aktiivilieteprosessi on herkkä ulkoisille ja sisäisille häiriöille. Jätevedenpuhdistukseen liittyvät ympäristövaatimukset ja päästöehdot vesistöihin ovat myös tiukentuneet, joten uusia menetelmiä tarvitaan parantamaan nykyisiä prosesseja. Tässä työssä kehitettiin uusi, optinen kuvantamismenetelmä karakterisoimaan flokkeja ja rihmoja. Menetelmä hyödyntää putkivirtausta ja CCD-kameraa ja sitä testattiin aktiivilietelaitosten näytteillä. Lisäksi kehitettiin samaa periaatetta noudattava online-laitteisto, jota testattiin kahdeksan kuukauden ajan. Optista kuvantamista testattiin laboratoriossa flokkien hajoamistutkimuksessa. Kuva-analyysitulosten perusteella kahden kunnallisen aktiivilietelaitoksen flokit hajosivat pintaeroosioon perustuvan mallin mukaan ja teollisen aktiivilietelaitoksen flokit hajosivat fragmentaatiomallin mukaan. Teollisen aktiivilietelaitoksen flokeissa oli enemmän rihmoja ja ne olivat epäsäännöllisemmän muotoisia, mikä voi olla syynä flokkien fragmentaatioon. Flokkien morfologian vaikutus jäteveden puhdistustuloksiin tutkittiin teollisessa (kolmen kuukauden ajan) ja kunnallisessa (kahdeksan kuukauden ajan) aktiivilietelaitoksessa optisella kuvantamismenetelmällä. Molemmissa laitoksessa muutokset flokkien morfologiassa tapahtuivat hitaasti. Neljä tärkeintä tekijää, jotka korreloivat puhdistustulosten kanssa, olivat flokkien koko ja muoto sekä pienten partikkelien ja rihmojen määrä. Kuva-analyysitulosten perusteella laskeutumisongelma teollisessa jätevesilaitoksessa johtui flokinmuodostajabakteerien liian pienestä määrästä ja kunnallisessa jätevesilaitoksessa rihmamaisten bakteerien liikakasvusta. Yhteenvetona voidaan todeta, että kehitettyä menetelmää on mahdollista käyttää online-mittarina sekä sen avulla voidaan arvioida flokkulaation tilannetta. Siten menetelmää on mahdollista hyödyntää flokkien ominaisuuksien karakterisoinnissa ja arvioidessa jätevedenkäsittelylaitoksen laskeutumisongelmien aiheuttajaa
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Sekhon, Bharpoor Singh. "Modeling of soil phosphorus sorption and control of phosphorus pollution with acid mine drainage floc." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2530.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2002.<br>Title from document title page. Document formatted into pages; contains xiv, 210 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Jackson, Suzanna Elizabeth. "Turbulence control of floc size in suspended particulate matter in the river estuary transition zone." Thesis, Bangor University, 2014. https://research.bangor.ac.uk/portal/en/theses/turbulence-control-of-floc-size-in-suspended-particulate-matter-in-the-river-estuary-transition-zone(a13e118b-c3e6-4c39-9c15-7f767df42466).html.
Full textAbstract:
The majority of terrestrially derived suspended particulate matter (SPM) is transported to the open ocean by rivers, therefore the river estuary transition zone (RETZ) represents a globally significant boundary separating the riverine and coastal regimes. The RETZ is comprised of the Tidally-Influence River (TIR), found above the limit of salt intrusion and the upper part of the estuary including the Estuarine Turbidity Maximum (ETM). The fate of SPM in the RETZ depends on its physical properties which are likely to be extremely variable in the RETZ which is characterised by large temporal and spatial gradients in hydrodynamic properties. Therefore, quantifying SPM properties in relation to physical forcings is key to determining the transfer flux of SPM from the catchment to the coastal ocean. The aim of this study is to interrogate the relationship between floc properties and the turbulence regime in the RETZ of a tidally dominated estuary over tidal, lunar and seasonal temporal scales. Flocs are fragile in nature and their properties fluctuate on short spatial and temporal scales; therefore in situ optical instruments (LISST-IOO and transmissometer) were deployed in the RETZ to obtain volume and mass concentrations of SPM. Turbulence measurements were determined via acoustic methods; ADCP and ADVs were deployed near to the bed to estimate TKE dissipation rates relating to the floc measurements. Data have been collected over five field campaigns, each included; spatial surveys characterising vertical profiles of SPM properties from the mouth of the estuary to the TIR, anchor station surveys measuring the temporal variations in SPM properties, bed-mounted mooring deployments in the RETZ and river surveys of the five main tributaries. Diurnal and semi-diurnal signals in floc properties in the RETZ were observed: resuspension occurred at peak tidal flows, usually on the flood tide; the maximum floc sizes corresponded with minimum effective densities and largely corresponded with high and low waters, as a result of particle flocculation during low turbulence conditions. Turbulence dissipation did not simply scale on tidal current velocities due to the additional contribution of wind stress and direction to the turbulence field. The Kolmogorov turbulence microscale correlated significantly with floc size during periods of marine conditions (i.e. the flood and early ebb tides) but showed a variable relationship during the late ebb when the RETZ was dominated by fluvial conditions and particles. This was most evident in the ETM where marine influence was greater compared to the TIR where it occurred only on larger tides. Thus floc size was related to the turbulence microscale but differences between flood and ebb relationships were probably due to different floc strengths of marine and terrestrial particles. During the lunar cycle, the variations observed on springs were repeated on neaps except that the flocculation signal occurred late in the flood rather than at high water. These tidal and lunar variations of particle properties in the RETZ were observed at all seasons.
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Löf, Ludwig. "Evaluation of Dissolved Air Flotation for Water Purification: With Focus on Floc Characteristics and PFAS." Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298378.
Full textAbstract:
I detta projekt har experiment utförts med mål att förse kommunalförbundet Norrvatten med data som kan användas som underlag för beslutsfattande angående om deras fällningslinjer i vattenreningsprocessen ska köras i flotation eller sedimentering. För detta ändamål har koncentrationen av poly- och perfluorerade alkylsubstanser (PFAS) samt karaktär av agglomererade partiklar (flockar) undersökts och jämförts mellan fällningslinjer som körs i olika konfigurationer. För flockkaraktär har skapandet och stabiliteten av flockar varit av intresse, eftersom flotation har ett mer turbulent flöde där flockarna riskerar att brista. Partikelstorlek, storleksfördelning och zeta potential identifierades som egenskaper som reflekterar flockarnas karaktär, dessa analyserades i en zetasizer. Koncentrationen av elva vanligt förekommande PFAS ämnen analyserades i projektet. Resultatet av flockkaraktär tyder på att det ej fanns någon större skillnad i skapandet av flockar samt deras stabilitet mellan de olika fällningslinjerna som undersökts. Detta eftersom zeta potentialen var identisk (-6.45 mV) för de analyserade proverna från respektive process. Analyserna och provberedningen bedömdes ha en hög mätosäkerhet, och några förbättringar som föreslås för att öka säkerheten är genomförande av komplementerande fotoanalys för att bekräfta likheter i utseende mellan flockar, samt att genomföra mer analyser så att en statistisk giltighet av analysen kan kvantifieras. För PFAS koncentrationen så var koncentrationen av PFAS lägre i utgående vatten från fällningslinje som körs i sedimentation (7.5 ng/l), jämfört med prov från linje som körs i flotation (9.2 ng/l). För fällningslinjen som kördes i flotation så skapades skum med höga koncentrationer av PFAS (3800 ng/l) jämfört med analyserade vattenprover (5.5–9.2 ng/l), detta identifierades som en potentiell källa för PFAS-avlägsning. Resultaten av PFAS baserades endast på en provtagningsserie, och förbättringar av validitet kan åstadkommas genom samling av mer analysdata för samma processer, och genom att analysera ett av proverna i två olika instrument, som båda analyserar PFAS koncentration.<br>In this project, attempts have been made to collect data that allows the municipal association Norrvatten in the decision-making process on the flotation/ sedimentation step of their water treatment process. In this sense, poly- and perfluorinated alkyl substances (PFAS) concentration and the characteristics of agglomerated particles (flocs) have been investigated and compared between the two modes that the process can be operated. For the floc characteristics, the creation and stability of the flocs were investigated, and the particle size, size distribution and zeta potential was identified as important properties and thereafter analysed using the instrument zetasizer. The concentration of eleven different PFAS compounds were analysed. The results of floc characteristics show that there is no major difference in creation and breakage of flocs in the two investigated modes, since the analysed samples had the same zeta potential, -6.45 mV. The results were deemed uncertain because of varying results, and improvement suggestions include using photoanalysis to confirm similar floc appearances and to produce more data so a statistical validity can be quantified. As for the PFAS concentration, the concentration of PFAS were slightly lower in the treatment step in which sedimentation was utilized (7.5 ng/l) compared to when flotation was utilized (9.2 ng/l). The flotation mode did, however, create foam with a high PFAS concentration (3800 ng/l) compared to the liquid samples (5.5-9.2 ng/l), so a potential PFAS removal source was identified. The results were based on one sample series, so improvements of validity can be achieved by gathering more data, analysing more samples, and analysing the same sample in two different instruments measuring PFAS concentrations.
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Kolda, Bridget C. "Impact of polymer type, dosage, and mixing regime and sludge type on sludge floc properties." Thesis, Virginia Tech, 1995. http://hdl.handle.net/10919/40662.
Full textAbstract:
<p>This research investigated the impact of sludge type, polymer type
(percent mole charge), dosage, mixing rate, and solution ionic strength on
bound water content of sludge flocs. Data determined to evaluate the
extent of dewatering included: percent dry solids, bulk density, bound
water content (determined by dilatometric method), floc density
(determined by isopycnic centrifugation), and cake solids concentrations.
Calculated floc densities and bound water contents were compared with
measured values.
The polymer mole charge had marginal impact on bound water
content. The optimal polymer dose as determined by dose curves did not
necessarily result in the least bound water content. The mixing rate did not
have an impact on bound water content of the chemical sludge, but did
have an impact on bound water content of the biological sludge. However,
the percentage of total water removed that was due to bound water
removal was not affected by rate of mixing, polymer mole charge, or
polymer dose. Altering solution ionic strength did not appear to improve
bound water removal.</p>
<p>The calculated bound water content values determined using
measured floc densities were consistently greater than the measured bound
water content values determined by dilatometric method. The bound water
content per the dilatometric method did not account for all the water
present in the floes as determined by the isopycnic centrifugation method.</p><br>Master of Science
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Finlayson, Jennine Carol. "The relationship between the sorption of organic contaminants and the structure of activated sludge floc material." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0013/MQ34114.pdf.
Full text
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Fennessy, Michael Jim. "Development and testing of an instrument to measure estuarine floc size and settling velocity in situ." Thesis, University of Plymouth, 1994. http://hdl.handle.net/10026.1/1836.
Full textAbstract:
An instrument has been developed to observe the settling of individual flocs in turbid water in order to to measure size and settling velocity spectra of estuarine cohesive suspended sediments. INSSEV - IN Situ SEttling Velocity instrument - is bed mounted and comprises a computer controlled decelerator chamber that collects a sample of water from which some of the suspended matter is allowed to enter the top of a settling column. The settling flocs are viewed using a miniature video system. Subsequent analysis of video tapes provides direct measurements of size and settling velocity of individual flocs down to 20 um. From this information floc effective density is estimated. The main feature of the instrument is its ability to video flocs in situ irrespective of the concentration in the estuary, with as little disturbance to their hydrodynamic environment as possible. In addition to size and settling velocity distributions, data analysis developed for the instrument produces spectra of concentration and settling flux with respect to size, settling velocity or effective density. This is the first time that these parameters have been measured in situ. Field testing in the Tamar Estuary, South West England, and the Elbe Estuary, Germany, has given useful results in flow velocities up to 0.6 m s-1 and in concentrations up to 400 mg l-1 INSSEV was used in the 1993 Elbe Intercalibration Experiment where nearly all types of instrumentation for the in situ determination of estuarine floc size and/or settling velocity were deployed over several tidal cycles. From observations in the turbidity maximum of the Tamar Estuary, INSSEV data has shown significant changes in floc population characteristics during the tidal cycle, the most important being changes in floc effective density. A strong relationship between floc effective density and ambient turbulence characteristics is shown.
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López, Miguel Arévalo. "Avaliação reprodutiva de machos de camarão rosa Farfantepenaeus duorarum cultivados em sistema BFT “Bio-Floc Tecnology”." reponame:Repositório Institucional da FURG, 2010. http://repositorio.furg.br/handle/1/2411.
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Dissertação(mestrado)-Universidade Federal do Rio Grande, Programa de Pós-Graduação em Aqüicultura, Instituto de Oceanografia, 2010.<br>Submitted by Cristiane Silva (cristiane_gomides@hotmail.com) on 2012-08-10T16:06:33Z
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Previous issue date: 2010<br>O camarão-rosa Farfantepenaeus duorarum é um importante recurso pesqueiro que apresenta distribuição no Oceano Atlântico desde o estado de Maryland nos EUA até a Bahia de Ascensión, no estado de Quintana Roo no México. O objetivo do presente trabalho foi avaliar a qualidade reprodutiva e nutricional de machos mediante a contagem e caracterização de células espermáticas originados de camarões mantidos em sistemas
convencionais com água clara e sistema de bioflocos. O experimento foi desenvolvido
em uma fase de terminação (60 dias), pré-maturação (30 dias) e de desempenho reprodutivo (45 dias). Os machos foram submetidos a três tratamentos: BF+P bioflocos
com ração comercial 35 % PB ; BF+PF biofloco com alimento fresco e ração e CR+PF água clara com alimento fresco e ração. Na fase de desempenho reprodutivo os camarões de todos os tratamentos seguiram para a sala de maturação onde foram alimentados com alimento fresco. Os parâmetros de qualidade de água durante as três fases do experimento não mostraram diferença significativa entre tratamentos (P>0,05) e estiveram nos níveis
adequados para o cultivo de camarões. Durante a fase de desempenho reprodutivo, não foram encontradas diferenças significativas (P>0,05) no número de células espermáticas totais entre tratamentos, sendo que o tratamento CR+PF apresentou 8,9±5,83 x106 células e os tratamentos BF+P e BF+PF apresentaram 12,35±10,2 e 12,96±5,2 x106 células respectivamente, com uma percentagem maior que 96% em todos os tratamentos, após
um período de 45 dias de desempenho reprodutivo. Não houve diferença significativa (P>0,05) nos dados de Índice Gonodosomático, entre tratamentos, na monstragem inicial nem na amostragem final. Os dados de metabólitos na gônada dos machos não apresentaram diferença significativa (P>0,05) entre tratamentos. Os dados de
Triglicerídeos e Colesterol na gônada não apresentaram diferença significativa. Já os
dados de proteínas totais no tratamento CR+RF foram diferentes estatisticamente dos
tratamentos BF+R e BF+RF. O Tratamento BF+P demonstrou ser uma opção para preparar machos reprodutores de F. duorarum.<br>The pink shrimp Farfantepenaeus duorarum it is an important fishery resource in Mexican Gulf. Its distribution in the Atlantic Ocean ranges from Maryland state (USA) to the Bay of Ascencion in the Quintana Roo state (Mexico). The objective of this study was to evaluate the reproductive and nutritional quality of males by counting and characterization of sperm cells originating from clear water and biofloc water system.
The experiment was conducted in a final period (60 days), pre-maturity (30 days) and
reproductive performance (45 days). The males were assigned to tree treatments: BF+P,
Bioflocs with commercial feed 35%CP ; BF+PF biofloc with fresh food and commercial feed and CR+PF clear water with fresh food and commercial feed. The water quality parameters during the three phases of the experiment showed no significant differences among treatments (P> 0.05) and were at the levels appropriate for shrimp farming. During the reproductive performance, there were no significant differences (P> 0.05) in the total number of sperm cells between treatments. The CR+FP treatment showed 8.9 ± 5.83 x106 cells and treatments BF+P and BF+PF
showed 12.35±12.96 and 10.2±5.2 x106 cells respectively, with a greater percentage to
96% in all treatments even after a period of 45 days of reproductive performance. There
was no significant difference (P> 0.05) in the Gonodosomatic Index between treatments
in initial sample and final sample. Data of metabolites of male gonad showed no significant difference (P>0.05) between treatments. Levels of Triglycerides and
Cholesterol in the gonad showed no difference, since the data of total protein treatment CR+PF was statistically different (P< 0.05) treatments BF+R and BF+R F. The BF+P treatment demonstrated in this work is an option for preparing F. duorarum males.
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Henriques, Inês Domingues. "Elucidating the Response of Activated Sludge Cultures to Toxic Chemicals at the Process, Floc and Metabolic Scales." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27937.
Full textAbstract:
Activated sludge treatment systems rely on a microbial consortium structurally organized in bioflocs to treat pollutants present in wastewater. The treatment process efficiency in these systems can be severely affected by toxic chemicals present in the influent wastewater. The effects of chemical toxins at the treatment process level are determined by the mechanisms that occur at the biofloc and cellular levels, which can be physical, chemical and physiological in nature. We believe that the overall process effects of chemical toxins on activated sludge systems likely result from a combination of all three types of mechanisms and that they are interdependent, in the sense that specific bacterial stress response mechanisms (physiological mechanisms that protect the cell from toxic conditions) may lead to physical/chemical alterations at the floc level, and vice-versa. Ultimately, understanding the mechanisms that occur at the floc and metabolic scales will help to design more robust and efficient treatment systems, and to develop tools to prevent and mitigate the effects of toxic chemicals on activated sludge systems. In this research, we set out to establish the link between the effects of chemical toxins on activated sludge cultures at the process, floc and metabolic scales.
First, the effects of shock loads of different toxic sources (1-chloro-2,4-dinitrobenzene (CDNB), cadmium, 1-octanol, 2,4-dinitrophenol (DNP), weakly complexed cyanide, pH 5, 9 and 11, and high ammonia levels) on activated sludge process parameters (biomass growth, respiration rate, flocculation, chemical oxygen demand (COD) removal, dewaterability and settleability) were studied. For all chemical shocks except ammonia and pH, concentrations that caused 15, 25 and 50% respiration inhibition were used to provide a single pulse chemical shock to sequencing batch reactor (SBR) systems containing a nitrifying (10 day solids retention time – SRT) and a non-nitrifying (2 day SRT) biomass. We found that cadmium and pH 11 shocks were the conditions that most detrimentally affected all the processes, followed by CDNB. DNP and cyanide primarily led to effects on respiration, while pH 5, 9, octanol and various ammonia concentrations did not impact the treatment process to a significant extent. Additionally, there was a clear correlation between biomass deflocculation and increases in the effluent soluble COD of the shocked reactors for different chemical sources. With this study, we were able to establish a source-effect matrix linking classes of chemical toxins to their potential inhibitory effects on activated sludge processes, thereby contributing to a better understanding of the potential effects of toxic industrial discharges into biological treatment systems.
The findings of the first phase of the research, specifically the correlation between chemical-induced deflocculation and increases in soluble COD, served as a motivation to explore the role of floc structure in the response of activated sludge cultures to toxic compounds, and to conduct a more in-depth analysis of the supernatant (soluble phase) of toxin-exposed activated sludge. In one study, we evaluated the respiration inhibition induced by octanol, cadmium, N-ethylmaleimide (NEM), cyanide and DNP on activated sludge biomasses with different floc structures but similar physiological characteristics, with the objective of assessing the role of the extracellular polymeric substances (EPS) in flocs as a protection barrier against chemical toxins. Mechanical shearing was applied to fresh mixed liquor to produce biomasses with different floc structure properties and specific oxygen uptake rate assays were conducted on the sheared and unsheared mixed liquors. The results showed that the respiration inhibition by octanol and cadmium was more intense in sheared mixed liquor (which had less EPS material available in the flocs and smaller floc sizes) than in the unsheared biomass. Conversely, the respiration inhibition induced by NEM and cyanide was similar for the different mixed liquors tested. These results allowed us to conclude that the EPS matrix functions as a protective barrier for the bacteria inside activated sludge flocs to chemicals that it has the potential to interact with, such as hydrophobic (octanol) and positively-charged (cadmium) compounds, but that the toxicity response for soluble, hydrophilic toxins (NEM and cyanide) is not significantly influenced by the presence of the polymer matrix.
In the final study that was conducted, we used the metabolomics-based technique metabolic footprinting to assess if the soluble phase of mixed liquor exposed to different chemical toxins exhibited a toxin-specific biochemical composition. We hypothesized that toxin-specific effects could be distinguished through footprint patterns of those soluble samples. The impact of cadmium, DNP and NEM shock loads on the composition of the soluble fraction of activated sludge mixed liquor was analyzed by liquid chromatography-mass spectrometry (LC-MS). The results from this study indicated that there was a significant release of biomolecules (proteins, carbohydrates and humic acids) from the floc structure into the bulk liquid due to chemical stress. More importantly, using a multivariate statistical method called discriminant function analysis with genetic algorithm variable selection (GA-DFA), we were able to show that the soluble phase samples from the different reactors could be differentiated, thereby indicating that the footprints generated by LC-MS were different for the four conditions tested and, therefore, toxin-specific. These footprints, thus, contain information about specific biomolecular differences between the samples, and we found that only a limited number of m/z (mass to charge) ratios from the mass spectra data was needed to differentiate between the control and each chemical toxin-derived samples. In addition, since the experiments were conducted with mixed liquor from four distinct wastewater treatment plants, the discriminating m/z ratios may potentially be used as universal stress biomarkers. These results are promising and indicate that LC-MS may be used for the discovery of activated sludge stress biomarkers, to allow the development of new toxin detection technologies for prevention of upset events in activated sludge systems.<br>Ph. D.
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Bergström, Roger. "Fibre flow mechanisms." Doctoral thesis, KTH, Fiber- och polymerteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240.
Full textAbstract:
The flow behaviour, and primarily the floc-floc interaction, of pulp paper suspensions have been studied visually. Analogy models based on these observations have been developed as well as the identification of important parameters of floc break-up in low shear rate flow fields. Floc compressions and the locations of voids (areas of lower fibre concentration) where found to influence the floc splitting mechanism. Based on this investigation an equipment for measuring the load carrying ability of fibre flocs and networks was designed, and the effect of measurement geometry, network structure and fibre suspension concentration was investigated. The load carrying ability with concentration increases rapidly when going from 1% to 2% in initial suspension concentration. A model handling the fibre floc behaviour during extension and compression has been developed, and some basic flocculated flow mechanisms are discussed on an analogy basis. A modified Voigt element is use, describing mainly the compressional behaviour and plastic behaviour of loose fibre network structures. Further the pos- sibility of stress chain formation is discussed on a fibre level as well as on a floc level. The effect of fibre flow (shear field) occurring in the forming zone of a roll former has been studied in detail. Basic forming mechanisms on floc scale has been investi- gated, and the effect of running parameters like dewatering pressure and jet-to-wire speed difference as well as the fibre type and concentration of the pulp suspension has been evaluated. It is evident that floc elongation increases with shear rate (jet-to-wire speed difference) and lower dewatering rate. The latter is because the fibre floc is subjected to the shear field longer due to slower immobilisation. Shorter fibre tends to create weaker networks, which promotes a higher elongation of the flocs.<br>QC 20100901
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Rouhnia, Mohamad. "Vertical Transport of Sediment from Muddy Buoyant River Plumes in the Presence of Different Modes of Interfacial Instabilities." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82506.
Full textAbstract:
This study focuses on deposition processes from sediment laden buoyant river plumes in deltaic regions. The goal is to experimentally examine the effects of various physical phenomena influencing the rate at which sediment is removed from the plume. Previous laboratory and field measurements have suggested that, at times, sedimentation can take place at rates higher than that expected from individual particle settling (i.e., C{W}_{s}). Two potential drivers of enhanced sedimentation are flocculation and interfacial instabilities. We experimentally measured the sediment fluxes from each of these processes using two sets of laboratory experiments that investigate two different modes of instability, one driven by sediment settling and one driven by fluid shear. The settling-driven and shear-driven instability sets of experiments were carried out in a stagnant stratification tank and a stratification flume respectively. In both sets, continuous interface monitoring and concentration measurement were made to observe developments of instabilities and their effects on the removal of sediment. Floc size was measured during the experiments using a separate floc camera setup and image analysis routines. Results from the stratification tank experiments suggest that the settling-driven gravitational instabilities do occur in the presence of flocs, and that they can produce sedimentation rates higher than those predicted from floc settling. A simple cylinder based force balance approach adopting the concept of critical Grashof number was used to develop a model for the effective settling velocity under settling-driven instabilities that is a function of sediment concentration in the plume only. Results from the stratification flume experiments show that under shear instabilities, the effective settling velocity is greater than the floc settling velocity, and increases with plume velocity and interface mixing. The difference between effective and floc settling velocity was denoted as the shear-induced settling velocity. This settling rate was found to be a strong function of the Richardson number, and was attributed to mixing processes at the interface. Conceptual and empirical analysis shows that the shear-induced settling velocity is proportional to U{Ri}^{-2}.
Following the experiments, analyses were made among contributions of different mechanisms on the total deposition rate, and the locations that the various mechanisms may be active in the length of a plume. This analysis leads to a conceptual discretization of a plume into three zones of sedimentation behavior and Richardson number. The first zone is the supercritical near-field plume with intense interface mixing. Zone two represents the subcritical region where interface mixing still occurs, and zone three is the high Richardson number zone where mixing at the interface is effectively nonexistent. In zones one and two, individual floc settling and shear-induced settling mechanisms play the major roles in removing sediment from the plume. While, shear-induced settling rate was found to be maximum near the river mouth, its share of the total settling rate increases in the crossshore direction, since sand and large particulates deposit near the inlet and only small particles (with relatively low settling velocity) remain as the plume propagates. The third zone, starts when the interfacial mixing diminishes and leaking commences.<br>Ph. D.
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Tripathi, Chandrashekhar. "Thermophilic aerobic biological treatment of bleached kraft pulp mill effluent and its effect on floc formation and settleability." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/NQ41328.pdf.
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Prombutara, Pinidphon. "Identification of Genes Involved in Flocculation by Whole Genome Sequencing of Thauera aminoaromatica Strain MZ1T Floc-defective Mutants." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822777/.
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Thauera aminoaromatica MZ1T, a floc-forming bacterium isolated from an industrial activated sludge wastewater treatment plant, overproduces exopolysaccharide (EPS) leading to viscous bulking. This phenomenon results in poor sludge settling and dewatering during the clarification process. To identify genes responsible for bacterial flocculation, a whole genome phenotypic sequencing technique was applied. Genomic DNA of MZ1T flocculation-deficient mutants were subjected to massively parallel sequencing. The resultant high-quality reads were assembled and compared to the reference genome of the wild type genome. We identified nine nonsynonymous mutations and one nonsense mutation putatively involved in EPS biosynthesis. Complementation of the nonsense mutation located in an EPS deacetylase gene restored the flocculating phenotype. The FTIR spectra of EPS isolated from the wild-type showed reduced C=O peak of the N-acetyl group at 1665 cm-1 as compared to the spectra of MZ1T floc-deficient mutant EPS, suggesting that the WT EPS was partially deacetylated. Gene expression analysis also demonstrated the deacetylase gene transcript increased before flocculation occurred. The results suggest that the deacetylation of MZ1T EPS is crucial for flocculation. The information obtained from this study will be useful for preventing viscous bulking and wastewater treatment system failure, and may have potential applications in the biotechnology sector for the controlled removal of cells.
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Suopajärvi, T. (Terhi). "Functionalized nanocelluloses in wastewater treatment applications." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526207797.
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Abstract The chemicals currently used for wastewater treatment are mainly based on synthetic inorganic or organic compounds. Oil-derived polyelectrolytes are used for the removal of colloidal solids from wastewater by flocculation and coagulation, for example, while activated carbon adsorbents are typically used to remove soluble impurities such as heavy metals and recalcitrance organic matter. Many of these chemicals have associated negative health impacts, and use of activated carbon has proved to be expensive. Moreover, the present synthetic chemicals are not readily biodegradable or renewable. Thus there is a high demand for “green” water chemicals which could offer a sustainable solution for achieving high-performance, cheap water purification. Water chemicals of a new type based on nano-scale particles (nanofibrils) derived from cellulose, i.e. nanocelluloses, are examined as possible bio-based chemicals for wastewater treatment. Two anionic nanocelluloses (dicarboxylic acid, DCC, and sulphonated ADAC) were tested as flocculants in the coagulation-flocculation treatment of municipal wastewater, while the flocculation performance of cationic nanocellulose (CDAC) was studied with model kaolin clay suspensions, and nanocelluloses produced from sulphonated wheat straw pulp fines (WADAC) were tested for the adsorption of lead (Pb(II)). The anionic nanocelluloses (DCC and ADAC) showed good performance in treating municipal wastewater in a combined coagulation-flocculation process with a ferric coagulant. In the case of both anionic nanocelluloses the combined treatment resulted in a lower residual turbidity and COD in a settled suspension with highly reduced total chemical consumption relative to coagulation with ferric sulphite alone. Likewise, the CDACs resulted in powerful aggregation of kaolin colloids and maintained effective flocculation performance over wide pH and temperature ranges. The capacity of the nanofibrillated and sulphonated fines cellulosics (WADAC) for the adsorption of Pb(II) was 1.2 mmol/g at pH 5, which is comparable to the capacities of commercial adsorbents<br>Tiivistelmä Jätevesien kemiallinen käsittely pohjautuu pääsääntöisesti synteettisten epäorgaanisten ja orgaanisten kemikaalien käyttöön. Öljypohjaisia polyelektrolyytteja käytetään kolloidisten partikkeleiden poistamiseen jätevesistä koaguloimalla ja flokkuloimalla, kun taas liuenneita epäpuhtauksia, kuten raskasmetalleja, poistetaan useimmiten adsorboimalla ne aktiivihiileen. Synteettiset vesikemikaalit valmistetaan uusiutumattomista luonnonvaroista ja niiden hajoaminen luonnossa voi olla hidasta, minkä lisäksi monet näistä käytetyistä synteettisistä vesikemikaaleista ovat terveydelle haitallisia. Aktiivihiilen käyttö puolestaan on kallista, johtuen sen korkeista valmistus- ja käyttökustannuksista. Uusille ”vihreille vesikemikaaleille, jotka tarjoavat ympäristöystävällisempiä, halpoja sekä tehokkaita ratkaisuja vedenpudistukseen, onkin suuri kysyntä. Tässä työssä selluloosasta valmistettuja nanokokoisia partikkeleita, eli nanoselluloosia, on tutkittu yhtenä varteenotettavana biovaihtoehtona uusiksi kemikaaleiksi jätevesien puhdistukseen. Kahden anionisen nanoselluloosan (dikarboksyyli, DCC, ja sulfonoitu, ADAC) flokkauskykyä testattiin koagulointi-flokkulointi reaktioissa kunnallisen jäteveden puhdistuksessa. Kationisen nanosellun (CDAC) flokkauskykyä tutkittiin puolestaan kaoliinisaven malliliuoksilla ja vehnän korsisellun hienoaineista nanofibrilloimalla sekä sulfonoimalla valmistetuilla (WADAC) nanoselluloosamateriaaleilla testattiin lyijyn (Pb(II)) adsorptiota vesiliuoksista. Anioniset nanoselluloosat (DCC ja ADAC) toimivat tehokkaasti kunnallisen jäteveden flokkauksessa ferri-sulfaatin kanssa yhdistetyissä koagulointiflokkulointi reaktioissa. Yhdistetyissä reaktioissa molemmat anioniset nanoselluloosat vähensivät sameutta sekä COD pitoisuutta laskeutetuissa jätevesinäytteissä huomattavasti pienemmillä kemikaalikulutuksilla paremmin kuin pelkästään ferri-sulfaatilla koaguloitaessa. Myös CDAC:t toimivat tehokkaasti flokkauksessa keräten tehokkaasti kaoliinin kolloidipartikkeleita yhteen laajalla pH- ja lämpötila-alueella. Nanofibrilloidun ja sulfonoidun vehnäsellun hienoaineen (WADAC) adsorptiokapasiteetti lyijylle Pb(II) oli 1.2 mmol/g pH:ssa 5, mikä on verrannollinen kaupallisten adsorptiomateriaalien kapasiteettiin
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Tran, Duc Anh. "Experiments on the Transformation of Mud Flocs in Turbulent Suspensions." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83606.
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This dissertation aims to better understand how floc aggregate characteristics and behaviors are modified under different local conditions and how such alterations impact the floc settling velocity, which is one of the most crucial parameters influencing sediment transport modeling.
A series of laboratory experiments were conducted to examine the impact of suspended sediment concentration, mixes of clay and silt, and resuspension process to equilibrium floc size and floc settling velocity. In order to observe floc size evolution, a new floc imaging acquisition was first developed. This new method allows flocs in suspended sediment concentration up to C = 400 mg/L can be imaged non intrusively. This new method was applied in all three individual studies, which are composed of this dissertation.
The first chapter investigates the behaviors of flocs under constant and decay suspended sediment concentrations within a steady turbulent suspension. In the constant-concentration set of experiments, floc size time series were measured for 12 h for each of the concentration C = 15, 25, 50, 100, 200, 300, and 400 mg/L. In the decay-concentration experiments, clear water was introduced to the mixing tank, simultaneously the suspension was drained out of the mixing tank at the same rate to make the suspended sediment concentration reduce while the turbulent shear was remained unchanged. The data shows that the equilibrium floc size is a weak, positive function of concentration. For example, in order to increase 20% of floc size (approximate 22 um) the concentration needs to be increased by 700% (going from 50 to 400 mg/L). The data also illustrates that during the decrease of concentration from C = 400 to 50 mg/L, the floc size responses to the changes of concentration in the order of 10 min or less.
The second chapter examines how silt particles and clay aggregates interact in a turbulent suspension. Floc sizes and settling velocity of three different suspensions, i.e., pure clay, pure silt, and a mixture of clay and silt, were monitored. The floc size data show that the presence of silt particles does not have significant impacts on clay aggregate sizes. Silt particles, however, get bound up within floc aggregates, which in turn increase the settling velocity of the floc by at least 50%.
The third chapter examines whether any changes in floc properties during the deposition and resuspension processes. The floc sizes and shapes in a set of experiments with different consolidation times, concentrations, and shear patterns were measured. The conditions at which the flocs deposited or resuspended were maintained the same. The data reveal that floc size and shape of freshly deposited and after resuspended are unchanged. The erosion rate and concentration is a function of consolidation time and the applied shear stress during the deposition phase. Hence, there is a small reduction in resuspended concentration resulting in a slight decrease in resuspension floc size since floc size is also a function of concentration.<br>Ph. D.
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Cheung, Mee Chu. "Comparative study of the structural, chemical and physical properties of activated sludge floc from different full-scale wastewater treatment systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0013/MQ33959.pdf.
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Fall, Kelsey. "Influence Of Suspended Particle Size And Composition On Particle Image Processing, Estuarine Floc Fractal Properties, And Resulting Estuarine Light Attenuation." W&M ScholarWorks, 2020. https://scholarworks.wm.edu/etd/1593091656.
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Understanding the nature of suspended particles is crucial to explaining water clarity issues in many estuaries, including the Chesapeake Bay and its tidal tributaries. Typical near surface estuarine particles are not individual sediment grains, but rather are clusters of inorganic and organic components known as flocs. Because of their fragile nature, flocs are challenging to observe in-situ, so their influence on the optical properties of the system are not well-known. This dissertation used a combination of state-of-the-art optical instrumentation, including laser scattering and transmissometry, a high-definition particle imaging camera system (PICS), and irradiance meters, along with supporting laboratory analysis techniques to investigate the surface waters of the York River estuary. This work characterized estuarine floc properties while simultaneously identifying relationships between estuarine light attenuation, absorption, and scattering due to flocs as well as other water column constituents. The relative organic fraction of suspended solids was found to be an important control on the fractal nature of estuarine flocs, including primary particle size and density, as well as bulk floc properties. A new approach is presented here that simultaneously solves for multiple floc fractal characteristics (e.g., fractal dimension, primary particle size, and primary particle density) and identifies whether simple fractal models are appropriate to describe individual suspensions. Results indicate that suspensions in the York River estuary with lower organic fraction and higher total suspended solids (TSS) are dominated by larger flocs composed of smaller, denser primary particles. In contrast, suspensions with higher organic fraction and lower TSS are composed of smaller flocs with larger, less dense primary particles. Paradoxically, the organic-rich flocs containing larger, lower density primary particles are, in terms of solids content, actually denser overall. This is because the larger, organic-rich primary particles take up more space within the flocs, leaving less room for water. Diffuse light attenuation, scattering, and absorption were related to the nature of the flocs in the York estuary, as well as to other water column constituents. It was found that as TSS increases, larger, lower density flocs containing less organic matter and more water increasingly dominate. This causes scattering to increase more quickly than TSS. In contrast, absorption increased more slowly than TSS. This is because the organics more prevalent at low TSS absorb more light per mass than the inorganic solids that dominate suspensions with higher TSS. Under most conditions, total scattering was dominated by inorganic particles. However, the combined effects of other components (the water itself, colored dissolved organic matter, phytoplankton, plus non-algal organic solids) typically dominated both absorption and attenuation. The importance of phytoplankton and organic solids relative to inorganic solids from land runoff have important ramifications for water clarity management, specifically suggesting revaluation of strategies solely focused on reducing inorganic sediment input. Even with an advanced video-settling column (e.g. PICS), there are issues resolving smaller flocs and sampling very low TSS. A major challenge in processing particle images is correctly identifying and sizing particles of varying composition and size, while correctly separating in-focus particles from out-of-focus particles. A new automated analysis approach was created that efficiently resolves particles, while rejecting out-of-focus objects, and was implemented into the automated processing algorithm for the PICS. Field- and laboratory-based experiments were conducted to evaluate video-based size, settling velocity, and density estimates, and it was found that all three parameters were adequately measured with the PICS.
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LI, BAIKUN. "REDOX POTENTIAL (ORP) REGULATION OF NUTRIENT REMOVAL IN WASTEWATER TREATMENT PROCESSES AND THE STRUCTURE - FUNCTION ANALYSIS OF ACTIVATED SLUDGE FLOC." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1020695786.
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Pouliot, Cédrick. "Acetate and poly-b-hydroxybutyrate (PHB) metabolism by the activated sludge floc community of a hardwood Kraft pulp and paper mill." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82401.
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This research followed acetate carbon (C) uptake, metabolism, and fate through a typical modern Kraft pulp and paper mill AS system. Freshly collected mill biomass (AS floc suspensions) was placed under conditions representing four key phases of AS biotreatment: (1) initial acetate uptake by aerated starved AS; (2) ongoing acetate uptake; (3) aerobic metabolism of acetate-loaded AS in acetate-stripped effluent; and (4) anaerobic, settled biomass metabolism. Conditions mimicked the mill system as closely as possible. Acetate carbon uptake kinetics and conversion to CO2, growth products, PHB, and secreted metabolites in each of the four phases were measured. The role of PHB synthesis in the initial stripping of acetate from mill effluent and the PHB production potential of this mill AS were also investigated.<br>Results showed that acetate was rapidly taken up by high-affinity systems in the AS. During the initial exposure of mill-starved AS, acetate greatly stimulated AS-O2 uptake, and was quickly converted to PHB and CO 2. Upon depletion of available effluent acetate, as occurs in the downstream sections of the aeration tank, O2-uptake rates decreased and the acetate-C stored in AS-PHB was slowly released as CO2, and partly used for growth. Under secondary clarifier-like anaerobic conditions, the AS released virtually no CO2. However, substantial amounts of PHB were used for growth under anaerobic conditions and a small proportion of the original acetate C exited the cells as organic acids.
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Milligan, Timothy George. "A laboratory assessment of the relative importance of turbulence, particle composition, and concentration in limiting maximal floc size and settling behaviour." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24980.pdf.
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