The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological enhanced phosphate removal
type: CreativeWork
description: 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 activat…
abstract: 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 activat…
author: De Haas, David Walter
language: eng
date published: 1998
date modified: 2026-07-24T01:33:49Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Civil Engineering

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/16090