The problem of eutrophication caused by the enrichment of water bodies through excessive nutrient inputs (particularly of phosphate) has become significant in Ireland and throughout the developed world. This project has attempted to develop an improved method to tackle the difficult problem of phosphorus (P) removal from treated municipal wastewaters, which constitute the major point source of phosphate discharge into inland lakes and rivers. The project was designed to build on previous attempts by the project team to develop an improved alternative both to the use of chemical precipitants and to the enhanced biological phosphorus removal (EBPR) process currently the major methods of achieving the levels of P reduction demanded by increasingly stringent European legislation. Each has significant drawbacks: the former is expensive and leads to increased levels of sludge production, while the latter can perform inconsistently in the low-strength, high-volume wastewaters characteristic of temperate latitudes. Earlier work by the project team at laboratory and pilot-plant scale indicated that the maintenance of mildly acidic conditions (about pH 6.0) in a fully aerobic conventional activated sludge process can achieve levels of P removal comparable to those attainable under the aerobic/anaerobic cycling regime characteristic of the EBPR process (which has an optimum operationally pH of 7 to 8): this phenomenon has been termed the ?acid-stimulated biological phosphorus removal? (ASBPR). The major aims of the current study were to subject ASBPR to a full-scale trial under normal operational conditions (funded by the project?s industrial partners Northern Ireland Water Ltd and the QUESTOR Centre), and to gain a better understanding of the biochemical mechanisms that underpin the phenomenon so that it might be exploited more fully. Full-scale trialling of ASBPR took place over a 12-month period at an 185-person equivalent, two-lane activated sludge plant serving a rural hamlet near Lisburn, Northern Ireland. Work was hampered by a number of operational difficulties, including periodic sludge washout through stormwater overload, the fouling of acid-dosing equipment with unscreened materials such as rags which resulted in excessive pH shifts, and the effects of illegal toxic inputs from a local industry. Results obtained were in consequence inconsistent. Nevertheless, they indicated that under ideal conditions (fully aerobic and where the pH was maintained at approximately 6.0), levels of P removal were almost 30% greater than those in the untreated control lane (operated under standard aerobic-activated sludge conditions). It is recommended however that these results be verified in further on-site trials to assess the robustness of the ASBPR process. Additionally, these trials indicated that control of pH dosing is a key factor in the overall process and that a multipoint pH control system needs to be developed to allow maintenance of the activated sludge pH within the range 6-6.2. Concurrent laboratory studies to better understand the nature of enhanced P accumulation by activated sludge microorganisms made very significant progress. A large number of process-relevant isolates were obtained and identified: the gene responsible for polymerisation of excess phosphate into the intracellular storage product, polyphosphate, was identified as polyphosphate kinase and its involvement demonstrated. In addition, new fluorimetric and enzymatic assay methods for the quantification of polyphosphate were developed. Finally, the transport mechanisms by which phosphate is accumulated under mildly acidic conditions were studied and the involvement of a novel, phosphate-insensitive, high-affinity transporter protein was shown. Despite this progress, the failure to obtain consistent levels of acid-stimulated P uptake during routine-activated sludge sampling, even under laboratory conditions, led the project team to consider the possibility that other biochemical interactions (other than a response to mild acid stress) might be involved in the phenomenon. New reports from the scientific literature on the involvement of reduced sulphur species in the accumulation of polyphosphate by marine microorganisms were investigated, and it was possible to show that adding sulphite routinely produced modest increases in the levels of P uptake by activated sludge microorganisms, though not to economically exploitable levels. Most encouragingly, however, the project team has very recently achieved a long-term goal it has identified in the laboratory a physiological response triggered in the stationary-phase cells of activated sludge microorganisms, which leads to a consistent elevation in the rates of phosphate uptake and levels of intracellular polyphosphate accumulation. Its relationship to the acid-stimulated phenomenon remains unclear but its manipulation appears to offer real prospects for routinely achieving the levels of P removal from wastewaters that would meet legislative consents and for providing the feedstock for a possible P-recovery and recycling technology. This will be the focus of future studies. Success would offer the prospect of a simple P-removal technology, with a proven biochemical basis, that could effectively compete with EBPR in many situations.

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McGrath, J. Quinn, J.   "A Novel Biotechnological Approach To Phosphorus Removal From Wastewaters". Associated datasets and digitial information objects connected to this resource are available at: Secure Archive For Environmental Research Data (SAFER) managed by Environmental Protection Agency Ireland https://eparesearch.epa.ie/safer/resource?id=060d8720-7aa0-102e-a0a4-f81fb11d7d1c (Last Accessed: 2025-03-15)

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SAFER-Data Display URL	https://eparesearch.epa.ie/safer/iso19115/display?isoID=200
Resource Keywords	acid stimulated biological P removal sludge water northern ireland
EPA/ERTDI/STRIVE Project Code	2005-ET-LS-10-M3
EPA/ERTDI/STRIVE Project Theme	Waste and Resource Management
Resource Availability:	Public-Open
Limitations on the use of this Resource	The reliability, quality and completeness of data gained through SAFER-Data is intended to be used in an education or research context. These data are not guaranteed for use in operational or decision-making settings. The EPA and SAFER-Data requests an acknowledgement (in publications, conference papers, etc) from those who use data/information received with SAFER-Data. This acknowledgement should state the original creators of the data/information. An automated citation is provided below. It is not ethical to publish data/information without proper attribution or co-authorship. The data/information are the intellectual property of the collecting investigator(s). The data/information may be freely downloaded and used by all who respect the restrictions and requirements in the previous paragraphs.
Number of Attached Files (Publicly and Openly Available for Download):	3
Project Start Date	Saturday 1st January 2005 (01-01-2005)
Earliest Recorded Date within any attached datasets or digital objects	Saturday 1st January 2005 (01-01-2005)
Most Recent Recorded Date within any attached datasets or digital objects	Wednesday 1st December 2010 (01-12-2010)
Published on SAFER	Wednesday 26th January 2011 (26-01-2011)
Date of Last Edit	Wednesday 26th January 2011 at 13:39:05 (26-01-2011)
Datasets or Files Updated On	Wednesday 26th January 2011 at 13:39:05 (26-01-2011)

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Description of Geographical Characteristics of This Project or Dataset
Full-scale trialling of ASBPR took place over a 12-month period at an 185-person equivalent, two-lane activated sludge plant serving a rural hamlet near Lisburn, Northern Ireland. At the onset of the project the industrial partners NI Water Ltd and the QUESTOR Centre invited the project team to initiate a full-scale trial of the ASBPR system. The team?s collaborators agreed to provide site rental, routine supervision, plant technical back-up, plant parts, power and other ancillary facilities. The collaborators had identifi ed an 185-person equivalent (30,000 L) aerated activated sludge plant located at Mullaghglass outside Belfast

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