New approaches to enhance pollutant removal in artificially aerated wastewater treatment systems

Freeman, Andy and Surridge, Benjamin William James and Matthews, Mike and Stewart, Mark and Haygarth, Philip Matthew (2018) New approaches to enhance pollutant removal in artificially aerated wastewater treatment systems. Science of the Total Environment, 627. pp. 1182-1194. ISSN 0048-9697

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Freshwater ecosystems sustain human society through the provision of a range of services. However, the status of these ecosystems is threatened by a multitude of pressures, including point sources of wastewater. Future treatment of wastewater will increasingly require new forms of decentralised infrastructure. The research reported here sought to enhance pollutant removal within a novel wastewater treatment technology, based on un-planted, artificially aerated, horizontal subsurface flow constructed wetlands. The potential for these systems to treat de-icer contaminated runoff from airports, a source of wastewater that is likely to grow in importance alongside the expansion of air travel and under future climate scenarios, was evaluated. A new configuration for the delivery of air to aerated treatment systems was developed and tested, based on a phased-aeration approach. This new aeration approach significantly improved pollutant removal efficiency compared to alternative aeration configurations, achieving > 90 % removal of influent load for COD, BOD5 and TOC. Optimised operating conditions under phased aeration were also determined. Based on a hydraulic retention time of 1.5 d and a pollutant mass loading rate of 0.10 kg d⁻¹ m⁻² BOD₅, > 95 % BOD5 removal, alongside final effluent BOD5 concentrations < 21 mg L-1, could be achieved from an influent characterised by a BOD5 concentration > 800 mg L-1. Key controls on oxygen transfer efficiency within the aerated treatment system were also determined, revealing that standard oxygen transfer efficiency was inversely related to aeration rate between 1 L and 3 L min-1 and positively related to bed media depth between 1,500 mm and 3,000 mm. The research reported here highlights the potential for optimisation and subsequent widespread application of the aerated wetland technology, in order to protect and restore freshwater ecosystems and the services that they provide to human society.

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Journal Article
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Science of the Total Environment
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This is the author’s version of a work that was accepted for publication in Science of the Total Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Science of the Total Environment, 627, 2018 DOI: 10.1016/j.scitotenv.2018.01.261
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26 Jan 2018 09:24
Last Modified:
06 Oct 2023 00:33