Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"backwash"”.
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Perspectives on the professional development of testing professionals in China — a mixed methods study of the roles of Chinese testing professionals in facilitating backwash effect
… facilitating quality education through positive backwash. This role is critical in contemporary China, not only due to its traditionally high-stakes exam and test-driven education system, but also its recent national strategic educational development plan with a goal to prepare for 21st century …
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Distribution and Characteristics of Biomass in an Upflow Biological Aerated Filter
… biomass in the bed and are present even after backwash. Protein was the major constituent of all fractions of the biomass. The ratio of carbohydrate to protein differed between fractions and between type of biofilms, with a larger value for detached and detachable fractions and a lower value …
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Sediment dynamics on Wemyss beach, South Fife
… transport, but enhanced movement in the backwash to low water. Coarse pebbles protruded from the mixed bed of closely packed small pebbles and generated turbulence, thus enhancing the lift forces for entrainment. Once in transport, the coarse pebbles 'overpassed' the small pebbles. …
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Assessment of the fate of manganese in oxide-coated filtration systems
… on the media. 2. Determination of the effect of backwash rate upon MnO<sub>x</sub>(s) coatings. 3. Examination of the effect of air scour upon MnO<sub>x</sub>(s) coatings. 4. Observation of the effect of an increasing MnO<sub>x</sub>(s) coating on the physical characteristics of anthracite coal …
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Near-bed hydrodynamics and sediment transport in the swash zone
… in the swash zone during both the uprush and the backwash. A detailed analysis of sheet flow focusing on quasi-steady backwash events (when effects of phase lags, surface-generated turbulence and accelerations were small) showed that the sheet flow sediment concentration profile has a linear shape …
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Modeling Powdered Activated Carbon Performance in Membrane Filtration Systems
… recirculation to a floc blanket reactor after backwash results in significantly lower carbon dose for a given adsorbate removal.
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The Impact of Aluminum on the Initiation and Development of MnOx(s) Coatings for Manganese Removal
… tests were conducted to examine Mn removal and backwash composition, while centrifugation and ultrafiltration were utilized to examine the potential for rapid Mn oxidation. Results indicate that the presence of Al augments the initiation and development of MnOx(s) coatings. The backwash solids …
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Design and Development of Scalable Solar Powered Water Purification Systems for Developing Nations
… and an ultraviolet light for disinfection. The backwash cycle extends the life of the ultrafiltration membrane to 4-7 years before a new filter is required. Simplicity in operation was an important design consideration because it facilitates local operator training, and understanding. To ensure …
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Transverse vibration as a fouling limitation strategy in membrane bioreactors
… improved when coupled with either periodic backwash or relaxation. However, periodic backwash during transverse vibration aided filtration increased the irreversible fouling incurred. Structural loads imposed on the fiber due to vibration were also studied using simulations. It was found …
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Transport of terrigenous sediment and horseshoe crab eggs in the swash zone of an estuarine foreshore in Delaware Bay, New Jersey, USA
… the step and transporting it downslope in the backwash. Results from the tracer experiments reveal that wave breaking is the primary mechanism that accounts for the greater quantities of sediment and eggs trapped from the mid-foreshore in the uprush relative to the backwash despite offshore …
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SPH modeling of the vertical flow structure and turbulence in the swash
… and hydraulic jumps that occur when a swash backwash collides with the following uprush. The model is initialized with a flat sea surface and the measured beach profile and is forced at the offshore boundary with waves observed in 5 m water depth. The model is used to simulate the cross-shore …
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A Tidal Prism analysis of the soluble copper mixing zone around the Occoquan Water Treatment Plant
… Approximately once a day, the treatment plant backwashes one of its five clarifier/filters and discharges this backwash water directly into the Occoquan River. Concern has risen that the plant may be concentrating this copper during treatment, and therefore may be responsible for violations in …
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Manganese oxide deposits in water treatment facilities, North East Scotland.
… difficult to remove, even during vigorous filter backwash cycles. If continuous application were not available, frequent shock doses of chlorine to the filter bed would help maintain oxide integrity. If no chlorine were present, manganese oxide deposits would be lost immediately during the next …
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Development of a Design Tool for Rapid Gravity Media Filtration in Water Treatment
… rate selection, operation and control, backwash rates, head losses, filter components, configuration and geometry. These parameters are documented in this dissertation and incorporated into the design tool, thus ensuring that the designer obtains relevant insights to the various …
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Bed shear stress under wave runup on steep slopes
… which remained constant during uprush and backwash (except around flow reversal). Friction factors remained consistent for many different wave cases, and appeared to be only affected by bed roughness. These results show much more consistency than previous studies, because of the quality of …
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Development of new membranes for desalination pre-treatment
… the performance of new and commercial membranes. Backwash system was introduced into the system to test the membranes for longer period of time. Membrane characterization is an essential part of development of the membrane. Pure water permeability and pore size distribution are the basic …
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The recovery of acetic acid from wastes of tanning extract manufacture
… which indicated its unsuitability; thereafter backwash rinse was used and found more satisfactory. The waste liquor used in the investigation was obtained from the 2nd and 3rd effects of a triple effect evaporator employed in the Mead Corporation Plant at Lynchburg, Virginia. Successive …
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Performance Evaluation and Yield Determination of a Full-Scale Biological Aerated Filter
… were made for filter media selection, backwash protocols, and hydraulic load effects. During the summertime monitoring, seeded and unseeded nitrified effluent BOD5 samples were performed on a full-scale BAF. Discrepancies were found between seeded and unseeded samples, which warranted …
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The morphological, sedimentary and hydraulic properties of two coarse clastic (pebble) beaches along the heritage coast of Glamorgan, Wales
… was the most susceptible parameter to swash/backwash processes, and that tracers possessing relatively larger C-axes travelled relatively further along and down-beach from the injection point. An analysis of the relationship between tracers and the background beach population showed …
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Evaluation of granular media to wastewater treatment; advanced primary treatment utilising modified pumice, titanomagnetite and ceramic nozzles.
… delivered air and water during filtration and backwashing. Investigation of the flow characteristics of the TMC nozzles showed that the major flow-regulating factor in the nozzle system was the water orifice in the bolt stem. Resistance in up-flow was consistently larger than resistance in …
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