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Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors
Yala, S. A. 2025. Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a524cbdc-94ef-4ce7-ab10-1e2301bc7bb2
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613987720396800 |
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| access_status_str | Open Access |
| author | Yala, Suzanne Akoth |
| author2 | Pillay, Visvanathan Lingam |
| author_browse | Pillay, Visvanathan Lingam Yala, Suzanne Akoth |
| author_facet | Pillay, Visvanathan Lingam Yala, Suzanne Akoth |
| author_sort | Yala, Suzanne Akoth |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Yala, S. A. 2025. Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a524cbdc-94ef-4ce7-ab10-1e2301bc7bb2 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132304 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:52.743Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132304 Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors Yala, Suzanne Akoth Pillay, Visvanathan Lingam Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Membrane separation Water -- Purification -- Membrane filtration Fouling Ultrafiltration UCTD Yala, S. A. 2025. Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a524cbdc-94ef-4ce7-ab10-1e2301bc7bb2 Thesis (PhD)--Stellenbosch University, 2025. ENGLISH ABSTRACT: Membrane fouling is a major operational challenge in membrane bioreactors (MBRs). It reduces membrane productivity and increases the operational cost of the system. Permeation drag due to applied pressure or flux, is one of the major contributors to membrane fouling. High drag force promotes deposition of foulants and compresses fouling layers, which consequently affects the overall performance of membranes in MBRs. Hence, prioir prediction and understanding of the effect of compression of fouling layers due permeation drag is essential for minimizing fouling and optimizing MBR operations. Mathematical models can be employed for such purposes. Therefore, this study developed a model that could predict the filtration performance of MBRs and also provide microscopic insight on membrane fouling under different compressions conditions. First, membrane filtration experiments of yeast suspension were carried at a laboratory scale under constant pressure and constant flux mode to obtain flux and pressure time profiles, respectively. The obtained data, which were inherently consistent and followed normal trend reported in literature, were used for modelling purposes. From the plots, it was observed that applied transmembrane pressure (TMP) and applied flux had a positive effect on the filtration performance of the membrane upto a certain limit, where a further increase did not increase permeate flux for constant pressure operations and resulted to a drastic increase in TMP for constant flux operations. The levelling off of flux at high applied TMPs and the drastic increase in TMP at high applied fluxes was attributed to compression of fouling layers. The second phase of the study involved modelling the effects of compression of fouling layer. A simple model that can predict the flux decline (constant pressure), TMP increase (constant flux) and profiles of fluid flow and fouling layer characteristic, based on filtration and compressibility of a feed, was proposed. The model was derived from conventional cake filtration theory, which involves combining equations that describe the compressibility of fouling layers and the fluid flow equations. The model parameters were estimated through fitting of experimental data of one run into the proposed equations. Thereafter, they were validated by data obtained from runs carried at different applied TMPs (10, 20, 50 & 60 kPa), applied fluxes (15, 25, 45, 55 LMH) and with different feed concentrations (6 & 8 g/L). Finally, the applicability of the model on real wastewater was tested. For all the evaluated conditions, the model satisfactorily predicted the filtration performance of the membranes. The F test, which compares the variances of the experimental data to that of the data predicted by the model, showed that all the F values were less than the F critical value of 2.2719. This indicates that the model predictions were consistent with the experimental data. Subsequently, it was successfully demonstrated how the proposed model can be used to optimize operations in an MBR. From the findings, it was concluded that the proposed model provides a valuable tool for predicting and optimizing the filtration performance of an MBR. However, further validation of the model with data from a full plant would be necessary. In addition, the model should be coupled with other supporting equations that describe other processes within an MBR, for comprehensive predictions and optimization. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Doctoral 2025-06-03T08:19:28Z 2025-06-03T08:19:28Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132304 en Stellenbosch University xx, 184 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Membrane separation Water -- Purification -- Membrane filtration Fouling Ultrafiltration UCTD Yala, Suzanne Akoth Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors |
| title | Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors |
| title_full | Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors |
| title_fullStr | Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors |
| title_full_unstemmed | Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors |
| title_short | Modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors |
| title_sort | modelling the effects of compression of fouling layers on the filtration performance of membrane bioreactors |
| topic | Membrane separation Water -- Purification -- Membrane filtration Fouling Ultrafiltration UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132304 |
| work_keys_str_mv | AT yalasuzanneakoth modellingtheeffectsofcompressionoffoulinglayersonthefiltrationperformanceofmembranebioreactors |