Optimisation of a hollow fibre membrane bioreactor for water refuse

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dc.contributor.advisorJudd, Simon J.
dc.contributor.authorVerrecht, Bart
dc.date.accessioned2011-12-07T10:24:51Z
dc.date.available2011-12-07T10:24:51Z
dc.date.issued2010-09
dc.description.abstractOver the last two decades, implementation of membrane bioreactors (MBRs) has increased due to their superior effluent quality and low plant footprint. However, they are still viewed as a high-cost option, both with regards to capital and operating expenditure (capex and opex). The present thesis extends the understanding of the impact of design and operational parameters of membrane bioreactors on energy demand, and ultimately whole life cost. A simple heuristic aeration model based on a general algorithm for flux vs. aeration shows the benefits of adjusting the membrane aeration intensity to the hydraulic load. It is experimentally demonstrated that a lower aeration demand is required for sustainable operation when comparing 10:30 to continuous aeration, with associated energy savings of up to 75%, without being penalised in terms of the fouling rate. The applicability of activated sludge modelling (ASM) to MBRs is verified on a community-scale MBR, resulting in accurate predictions of the dynamic nutrient profile. Lastly, a methodology is proposed to optimise the energy consumption by linking the biological model with empirical correlations for energy demand, taking into account of the impact of high MLSS concentrations on oxygen transfer. The determining factors for costing of MBRs differ significantly depending on the size of the plant. Operational cost reduction in small MBRs relies on process robustness with minimal manual intervention to suppress labour costs, while energy consumption, mainly for aeration, is the major contributor to opex for a large MBR. A cost sensitivity analysis shows that other main factors influencing the cost of a large MBR, both in terms of capex and opex, are membrane costs and replacement interval, future trends in energy prices, sustainable flux, and the average plant utilisation which depends on the amount of contingency built in to cope with changes in the feed flow.en_UK
dc.identifier.urihttp://dspace.lib.cranfield.ac.uk/handle/1826/6779
dc.language.isoenen_UK
dc.publisherCranfield Universityen_UK
dc.rights© Cranfield University 2010. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright owner.en_UK
dc.subjectAeration energyen_UK
dc.subjectAeration intensityen_UK
dc.subjectActivated sludge modelling (ASM)en_UK
dc.subjectBiokineticsen_UK
dc.subjectCapexen_UK
dc.subjectCost sensitivityen_UK
dc.subjectIntermittent aerationen_UK
dc.subjectLarge scaleen_UK
dc.subjectLife cycleen_UK
dc.subjectModel-based energy optimisationen_UK
dc.subjectOpexen_UK
dc.subjectSustainable operationen_UK
dc.subjectSmall scaleen_UK
dc.titleOptimisation of a hollow fibre membrane bioreactor for water refuseen_UK
dc.typeThesis or dissertationen_UK
dc.type.qualificationlevelDoctoralen_UK
dc.type.qualificationnamePhDen_UK

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PhD, EngD, MPhil and MSc by research theses (SAS)