The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal

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dc.contributor.authorDe Haas, David Walteren_ZA
dc.date.accessioned2016-01-02T04:18:56Z
dc.date.available2016-01-02T04:18:56Z
dc.date.issued1998en_ZA
dc.descriptionIncludes bibliographies.en_ZA
dc.description.abstractSince its first full-scale implementation in the late 1970s, considerable practical experience has been gained with biological enhanced phosphate removal (BEPR) in activated sludge systems for treating wastewater. However, BEPR tends to be sensitive and subject to many fluctuations, making it difficult to achieve full compliance with discharge standards. Simultaneous chemical addition in the activated sludge systems is a practical and economically attractive means of increasing the phosphate (P) removal capacity of these systems. However, it is also clear that the economic benefit of building a BEPR system could be lost if simultaneous addition of chemicals results in significant inhibition of the biological P removal mechanism. In South Africa anecdotal evidence of such inhibition has emerged. In view of its fundamental importance to the design and operation of BEPR plants which incorporate simultaneous chemical addition, it was considered imperative that the impact of simultaneous chemical addition on the biological P removal mechanism be investigated further, particularly with a view to addressing possible outstanding questions arising from re-interpretation of earlier work. Experimental work was conducted using two identical pilot (or laboratory-scale) activated sludge plants operated such that the BEPR phenomenon was strongly exhibited. The two plants were operated in parallel under identical conditions. Chemical precipitant (aluminium sulphate, ferric chloride or ferrous chloride) was dosed into one plant (the Test unit), while the other served as Control. As a means of distinguishing the chemically-precipitated phosphate content of the mixed liquor from biologically-stored phosphate (or poly P) pool, methods for chemical fractionation of the phosphate compounds in activated sludge were investigated. A fractionation procedure was adopted which appeared to be capable of broadly distinguishing between chemical and biological forms of stored phosphorus in activated sludge and showed satisfactory agreement with the predicted results for BEPR obtained using a mathematical model of such systems. However, caution in interpretation of the fractionation data was advised since artefacts imposed by the fractionation procedure itself may be difficult to avoid.en_ZA
dc.identifier.apacitationDe Haas, D. W. (1998). <i>The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering. Retrieved from http://hdl.handle.net/11427/16090en_ZA
dc.identifier.chicagocitationDe Haas, David Walter. <i>"The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 1998. http://hdl.handle.net/11427/16090en_ZA
dc.identifier.citationDe Haas, D. 1998. The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - De Haas, David Walter AB - Since its first full-scale implementation in the late 1970s, considerable practical experience has been gained with biological enhanced phosphate removal (BEPR) in activated sludge systems for treating wastewater. However, BEPR tends to be sensitive and subject to many fluctuations, making it difficult to achieve full compliance with discharge standards. Simultaneous chemical addition in the activated sludge systems is a practical and economically attractive means of increasing the phosphate (P) removal capacity of these systems. However, it is also clear that the economic benefit of building a BEPR system could be lost if simultaneous addition of chemicals results in significant inhibition of the biological P removal mechanism. In South Africa anecdotal evidence of such inhibition has emerged. In view of its fundamental importance to the design and operation of BEPR plants which incorporate simultaneous chemical addition, it was considered imperative that the impact of simultaneous chemical addition on the biological P removal mechanism be investigated further, particularly with a view to addressing possible outstanding questions arising from re-interpretation of earlier work. Experimental work was conducted using two identical pilot (or laboratory-scale) activated sludge plants operated such that the BEPR phenomenon was strongly exhibited. The two plants were operated in parallel under identical conditions. Chemical precipitant (aluminium sulphate, ferric chloride or ferrous chloride) was dosed into one plant (the Test unit), while the other served as Control. As a means of distinguishing the chemically-precipitated phosphate content of the mixed liquor from biologically-stored phosphate (or poly P) pool, methods for chemical fractionation of the phosphate compounds in activated sludge were investigated. A fractionation procedure was adopted which appeared to be capable of broadly distinguishing between chemical and biological forms of stored phosphorus in activated sludge and showed satisfactory agreement with the predicted results for BEPR obtained using a mathematical model of such systems. However, caution in interpretation of the fractionation data was advised since artefacts imposed by the fractionation procedure itself may be difficult to avoid. DA - 1998 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1998 T1 - The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal TI - The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal UR - http://hdl.handle.net/11427/16090 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/16090
dc.identifier.vancouvercitationDe Haas DW. The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 1998 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/16090en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Civil Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherCivil Engineeringen_ZA
dc.titleThe use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removalen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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