Graduate Thesis Or Dissertation
 

High-shear and pressure activated sludge treatment : solid-liquid separation

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/6108vd625

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  • Since the development of the activated sludge process in 1913 many attempts have been made to improve it. One approach has been to increase the oxygen available to the bio-mass. This study combined the use of elevated pressure and high-shear mixing to increase the oxygen transfer. The conventional method of separating activated sludge has been flocculation followed by sedimentation. High-shear mixing breaks up the bio-mass thus hindering flocculation. Flotation, a method of solid-liquid separation used in industrial processes, could utilize the dissolved air released when the elevated pressure is released. A laboratory-scale, activated sludge treatment unit was operated at various combinations of pressure and mixing. The solid-liquid separation characteristics of the mixed liquor were studied. Separation by settling was investigated when the unit was operated at atmospheric pressure and separation by flotation was investigated when the unit was operated at an elevated pressure of 30 psig. It was concluded from these tests that: (1) the effluent provided by sedimentation and flotation following medium and high-shear mixing is not adequate for discharge to most water-courses. (2) Flotation does not yield as clear an effluent as sedimentation. (3) Suspended solids removal by flotation requires a shorter detention time than by sedimentation. (4) Flotation yields a denser sludge than sedimentation. (5) In the flotation process no advantage was found by using a pressure release of more than 20 psi.
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Déclaration de droits
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  • File scanned at 300 ppi using ScandAll PRO 1.8.1 on a Fi-6770A in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
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