Advisor

Scott Wells

Date of Award

1990

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Civil Engineering

Physical Description

1 online resource (182 p.)

Subjects

Sewage tanks, Sewage -- Purification, Density currents

DOI

10.15760/etd.5969

Abstract

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.

Description

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Persistent Identifier

http://archives.pdx.edu/ds/psu/23465

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