No description available.

Thesis (Ph. D.)--Oregon Graduate Center, 1986.

No description available.

Thesis (Ph. D.)--University of Canterbury, 2002. / Typescript (photocopy). Includes bibliographical references (p. 243-260). Also available via the World Wide Wide.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 175-187). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. Document formatted into pages; contains xvi, 184 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 145-147).

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Apr. 1, 2010). Includes bibliographical references (p. 96-99).

Deviations from ideal flow and settling occur in circular wastewater treatment tanks because of tank geometry, flow conditions, and density currents caused by variations in suspended solids concentration and temperature distributions. Thermally induced density currents were investigated in this study. Under winter, low flow conditions, measurements were made of vertical and radial temperature distributions in the circular chlorination tank at Lake Oswego, Or., and in the circular primary and secondary clarifiers at Bend, Or. Thermistor arrays were used to collect the data which exhibited both vertically well-mixed and a two-layer flow regime. Inlet geometry and suspended solids in the secondary clarifiers caused a warm bottom inflow and apparent thermal instability. Meteorological measurements were also made. The calculated winter heat loss values indicated that convective mixing may have inhibited particle sedimentation in the clarifiers.

No description available.

The performance of settling tanks depends on several interrelated processes and factors that include: hydrodynamics, settling, turbulence, sludge rheology, flocculation, temperature changes and heat exchange, geometry, loading, the nature of the floc, the atmospheric conditions and the total dissolved solids concentration. A Quasi-3D (Q3D) clarifier model has been developed to include the following factors: axisymmetric hydrodynamics (including the swirl component), five types of settling (nonsettleable particles, unflocculated discrete settling, flocculated discrete settling, hindered settling and compression), turbulence, sludge rheology, flocculation with four classes of particles, temperature changes and surface heat exchange with the atmosphere, various external and internal geometry configurations, unsteady solids and hydraulic loading, the nature of the floc settling/interaction. The model includes: shear flocculation, differential settling flocculation and sweep flocculation. The Q3D model reproduces the major features of the hydrodynamic processes and solids distribution on secondary clarifiers. When the model is executed with the field derived settling characteristics, it can accurately predict the effluent and recirculation suspended solids concentrations. The model has been formulated to conserve fluid, tracer and solids mass. The model has been developed and tested using field data from the UNO Pilot Plant and the Jefferson Parish Waste Water Treatment Plant located at Marrero, Louisiana. A field testing procedure is presented that addressees all of the settling regimes that are encountered in a Secondary Settling Tank. Results obtained with the Q3D model indicate that the flocculation process plays a major role in the effluent suspended solids (ESS) on secondary clarifiers. The extent of actual flocculation depends on the design of the center well and on the concentration of the incoming mixed liquor suspended solids (MLSS). The center well promotes flocculation, but its most important benefit is the improvement on the tank hydrodynamics. The changes in temperature on secondary clarifiers play an important role on the performance of secondary settling tanks. The gravity induced radial velocities in the sludge blanket are higher than the radial velocities of the scraper in the region near the hopper, therefore the blades are not highly effective in conveying the solids in this region.