Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications
Thesis (MEng)--Stellenbosch, 2020.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2020
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613915612971008 |
|---|---|
| access_status_str | Open Access |
| author | Yala, Suzanne Akoth |
| author2 | Pillay, Visvanathan Lingamvrthi |
| author_browse | Pillay, Visvanathan Lingamvrthi Yala, Suzanne Akoth |
| author_facet | Pillay, Visvanathan Lingamvrthi Yala, Suzanne Akoth |
| author_sort | Yala, Suzanne Akoth |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch, 2020. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/109338 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:44.261Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/109338 Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications Yala, Suzanne Akoth Pillay, Visvanathan Lingamvrthi Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Fluorocarbon UCTD Textured woven fabrics Membrane reactors Fouling -- Organic Thesis (MEng)--Stellenbosch, 2020. ENGLISH ABSTRACT: Developing countries are faced with the major challenge of providing safe and adequate sanitation to their citizens. Decentralized sanitation systems have a great potential to address this challenge. The woven fabric immersed membrane bioreactor (WF-IMBR) technology is a promising option for such systems. This technology employs robust woven fabric microfilter (WFMF), developed in South Africa. However, organic fouling poses a major challenge to its application. Fine organics tend to penetrate the membrane, reduce productivity, and make cleaning difficult. Hence, the overall aim of this study was to develop and evaluate an oleophobic WFMF (OWFMF) membrane, which could repel organics. First, the fouling characteristics of the WFMF membrane were investigated by performing filtration and membrane cleaning experiments on a laboratory filtration unit, using 0.5 g/L of yeast suspensions as synthetic wastewater. From the flux and pressure drop profiles, fouling resistance profiles were generated. The fouling resistance profiles showed that fouling occurred in two stages, namely rapid irreversible fouling followed by progressive cake layer formation. The irreversible fouling occurred within the first five to ten minutes of filtration and could not be removed by water scouring, air scouring or backwashing. The cake layer could easily be removed by these methods. Photomicrographs of the cleaned and fouled membranes revealed that the irreversible foulants settled at the intersections of groups of fibres, where water scouring, and air scouring were unable to reach. The second phase of the study focused on the development of an OWFMF membrane. The process involved chemically bonding fluorocarbons onto a standard WFMF membrane through a pad-dry-cure process. The process was optimized using a 33full factorial design. The factors considered include fluorocarbon concentration (40 –80 g/L), padding pressure (0.5 –3.5 bar) and fabric speed (1 –3.5 m/min).The optimum conditions were identified as: 80g/L fluorocarbon concentration; 2 bar padding pressure; and 1 m/min fabric speed at 20 g/L wetting agent concentration, 180 ̊curing temperature and 90 seconds curing time.Unlike the standard WFMF which was non-oleophobic, i.e. oil droplets easily penetrated the fabric, the developed OWFMF membrane showed a high oleophobicity with an oil contact angle of 123.5 ̊. In the third stage, the OWFMF and the standard WFMF membranes were then compared in terms of pure water fluxes, permeate quality, fouling characteristics and ease of cleaning. This was done on yeast suspensions. Compared with the standard WFMF membrane, the OWFMF membrane showed a 60% reduction of the irreversible fouling resistance after five cycles of filtration and cleaning. This indicated that the oleophobic surface was very effective at repelling most of the organics; which made the cleaning of the membrane easier. Furthermore, the OWFMF membrane had a slightly enhanced flux when compared to the standard WFMF, and yet still achieved a permeate turbidity of below 1 NTU. In terms of stability, the oleophobic surface was fairly stable and only initial minimal erosion wasobserved.With the improved fouling resistance and ease of cleaning, the OWFMF membrane has a great potential for decentralized sanitation applications in developing countries. However, further performance evaluation of the long-term stability and performance on real wastewaters will be necessary. AFRIKAANSE OPSOMMING: Ontwikkelende lande staar groot uitdagings in die gesig om veilige en voldoende sanitasie aan hul burgers te verskaf. Gedesentraliseerde sanitasiestelsels het groot potensiaal om hierdie uitdaging aan te spreek. Die geweefde materiaal onderdompelde membraan bioreaktor (WF-IMBR) is ’n belowende opsie vir sulke stelsels. Hierdie tegnologie gebruik ’n robuuste materiaal mikrofilter (WFMF), ontwikkel in Suid-Afrika. Organiese aanpakking is egter ’n groot uitdaging vir die toepassing hiervan. Fyn organiese materiaal neig om deur die materiaal te penetreer, wat produktiwiteit verminder, en die skoonmaak bemoeilik. Daarom was die algehele doel van hierdie studie om ’n oleofobiese WFMF (OWFMF)-membraan te ontwikkel en te evalueer, wat organiese materiaal kan afweer. Eerstens is die aanpakkingseienskappe van die WFMF-membraan ondersoek deur filtrasie en skoonmaak van die membraan op ’n laboratorium filtrasie-eenheid uit te voer, deur 0.5 g/L gissuspensie as sintetiese afvalwater te gebruik. Vanaf die fluks en drukvalprofiele, is aanpakkingsweerstandprofiele gegenereer. Die aanpakkingsweerstandprofiele het gewys dat aanpakking in twee fases voorkom, naamlik vlugtige onomkeerbare aanpakking gevolg deur progressiewe koeklaagformasie. Die onomkeerbare aanpakking kom voor binne die eerste vyf tot tien minute van filtrasie en kan nie deur waterskuring, lugskuring of terugspoeling verwyder word nie. Die koeklaag kon maklik deur hierdie metodes verwyder word. Fotomikrograwe van die skoongemaakte en aangepakte membrane het getoon dat die onomkeerbare bevuilers afgesak het by die interseksies van groepe van vesels waar waterskuring en lugskuring dit nie kon bereik nie. Die tweede fase van die studie het op die ontwikkeling van ’n OWFMF-membraan gefokus. Die proses behels die chemiese verbinding van fluoorkoolstowwe op ’n standaard WFMF-membraan deur ’n belaai-droog-nabehandelingsproses. Die proses is geoptimeer deur ’n 33vol faktoriaalontwerp te gebruik. Die faktore oorweeg het fluoorkoolstofkonsentrasie (40 –80g/L), drukkingsdruk (0.5 –3.5 bar) en materiaalspoed (1 –3.5 m/min) ingesluit. Die optimale kondisies is geïdentifiseer as: 80 g/l van fluoorkoolstofkonsentrasie; 2 bar drukkingsdruk; en 1 m/min materiaalspoed teen 20 g/L benattingsmiddelkonsentrasie, 180 °C nabehandelingstemperatuur en 90 sekondes nabehandelingstyd. Anders as die standaard WFMF wat nie-oleofobies is, i.e. oliedrupples penetreer maklik die materiaal, het die OWFMF-membraan ’n hoë oleofobisiteit getoon met ’n oliekontakhoek van 123.5°. In die derde fase is die OWFMF-en die standaard WFMF-membrane vergelyk in terme van suiwer water flukse, deurlaatkwaliteit, aanpakkingskarakteristieke en skoonmaakgemak. Dit is gedoen op gissuspensie. In vergelyking met die standaard WFMF-membraan, het die OWFMF-membraan ’n 60% reduksie van die onomkeerbare aanpakkingsweerstand getoon na vyf siklusse van filtrasie en skoonmaak. Dit het aangedui dat die oleofobiese oppervlak baie effektief was met die afwering van meeste van die organiese materiaal; wat die skoonmaak van die membraan vergemaklik. Verder het die OWFMF-membraan ’n effense vergrote fluks gehad in vergelyking met die standaard WFMF, en het tog steeds ’n deurlaattroebelheid van onder 1 NTU bereik. In terme van stabiliteit, was die oleofobiese oppervlak redelik stabiel en is slegs aanvanklike minimale erosie waargeneem.Met die verbeterde aanpakkingsweerstand en skoonmaakgemak, het die OWFMF-membraan groot potensiaal vir gedesentraliseerde sanitasietoepassing in ontwikkelende lande. Verdere evaluasie op langtermyn stabiliteit en werkverrigting op regte afvalwater is egter nodig. Masters 2020-11-25T15:19:04Z 2021-01-31T19:45:23Z 2020-11-25T15:19:04Z 2021-01-31T19:45:23Z 2020-12 Thesis http://hdl.handle.net/10019.1/109338 en_ZA Stellenbosch University 184 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fluorocarbon UCTD Textured woven fabrics Membrane reactors Fouling -- Organic Yala, Suzanne Akoth Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications |
| title | Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications |
| title_full | Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications |
| title_fullStr | Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications |
| title_full_unstemmed | Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications |
| title_short | Development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications |
| title_sort | development of an oleophobic woven fabric microfiltration membrane for decentralized sanitation applications |
| topic | Fluorocarbon UCTD Textured woven fabrics Membrane reactors Fouling -- Organic |
| url | http://hdl.handle.net/10019.1/109338 |
| work_keys_str_mv | AT yalasuzanneakoth developmentofanoleophobicwovenfabricmicrofiltrationmembranefordecentralizedsanitationapplications |