Advanced reactor technology for wastewater treatment.

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dc.contributor.advisorStephenson, Tom
dc.contributor.advisorCartmell, Elise
dc.contributor.authorHassard, Francis
dc.date.accessioned2024-01-23T14:45:37Z
dc.date.available2024-01-23T14:45:37Z
dc.date.issued2015-04
dc.description.abstractElevated stringency regarding discharges and an aging asset base represent challenges to modern wastewater treatment. This requires upgrade of existing wastewater assets for low energy nutrient removal for minimal cost. Advanced rotating biofilm reactors can be used as a pre-treatment, high organic loading rate (OLR), low hydraulic residence time (HRT) treatment facilitating upgrade of existing wastewater treatment plant (WWTP). The threshold for stable nitrification in rotating biological contactors (RBCs) was assumed to be 15 g.BOD₅.m⁻²d⁻¹ however media modifications have shown that this value can be elevated to ~35 g.sCOD.m⁻²d⁻¹ (73.5 g.BOD₅.m⁻²d⁻¹ ) in rotating biofilm reactors (RBR). Mesh media was compared to two different reticulated foam media, the mesh media had similar porosities but elevated performance compared to the foam media. Elevated OLR resulted in lower volumetric bacterial viability suggesting inhibition at >100 g.sCOD.m⁻²d⁻¹. Comparison of four different mesh media suggested that high porosity mesh media is best for performance and to prevent pore clogging. Bacterial specific activity increased with OLR, but performance at very high OLR decreased. Biofilm reactors can be operated in a ‘hybrid’ configuration where settled bacterial solids can be recycled into the biofilm reactor to improve performance by reducing the effective biofilm OLR. Studies at full scale revealed that extracellular enzyme activity was higher in biofilms compared to suspended growth bacteria. Hybrid upgrade of existing wastewater treatment works resulted in 52 and 40% increase in removal rate of COD and NH₄-N respectively. Comparing different solids type for hybrid reactors utilising activated sludge flocs had the greatest performance benefit compared to HS and FE respectively for sCOD and NH₄-N removal. Incorporating a solids feed in hybrid reactors improved nitrification and organics removal at lower loading. However the solids in the recycle feed reduced denitrification at very high OLR suggesting flocs inhibit denitrification. Hybrid RBRs have 4.8 fold increase in protein EEA compared to single pass reactors under similar conditions. Recycling bacterial solids reduces the effective OLR on the biofilm and confers significant performance benefits. Upfront RBRs provide suitable upgrade for existing WWTP.en_UK
dc.description.coursenamePhD in Wateren_UK
dc.identifier.urihttps://dspace.lib.cranfield.ac.uk/handle/1826/20707
dc.language.isoenen_UK
dc.publisherCranfield Universityen_UK
dc.publisher.departmentSWEEen_UK
dc.rights© Cranfield University, 2015. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.en_UK
dc.subjectBiofilmen_UK
dc.subjectextracellular enzyme activityen_UK
dc.subjectHYBACSen_UK
dc.subjectHYFILTen_UK
dc.subjecthybrid activated sludgeen_UK
dc.subjecthybrid filtrationen_UK
dc.subjectmicrobial activityen_UK
dc.subjectorganic loading rateen_UK
dc.subjectrotating biological contactoren_UK
dc.subjectrotating biofilm reactoren_UK
dc.subjectsolids recycleen_UK
dc.subjectSMART uniten_UK
dc.subjectviabilityen_UK
dc.titleAdvanced reactor technology for wastewater treatment.en_UK
dc.typeThesis or dissertationen_UK
dc.type.qualificationlevelDoctoralen_UK
dc.type.qualificationnamePhDen_UK

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