Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Fouling is readily acknowledged as one of the most critical problems limiting the
wider application of membranes in liquid separation processes. A better
understanding of fouling layer formation and its monitoring is needed in order to
improve on existing cleaning techniques. Plant operation can be optimised if fouling
can be monitored by noninvasion means either on the plant itself or on an attached
monitoring device.
The overall scope of this research was to develop a non-destructive, real-time, in situ
visualisation technique or device for concentration polarisation and fouling layer
monitoring. Ultrasonic-time-domain-reflectometry (UTDR) was employed as a
visualisation technique to provide real-time characterisation of the fouling layer.
A 24 cm-long rectangular flat sheet aluminium cell was designed and used as
separation device for a desalination system. The experimental results obtained using
this module confirmed that there are an excellent correspondence between the flux
decline behaviour and the UTDR response from the membrane. The ultrasonic
technique could effectively detect fouling layer initiation and growth on the
membrane in real-time. In addition to the measurement of fouling, the ultrasonic
technique was also successfully employed for monitoring membrane cleaning. Since
no real-time permeation data is available during cleaning operations in industrial
applications, a UTDR monitoring device may prove to be a very valuable technique
in optimising cleaning strategies.
The technique was further tested on an 8-inch diameter spiral wrap industrial
module and good results were obtained. Stagnant zones, as well as flux flow
behaviour inside the module could be determined. However, more research IS
needed to fully understand the complex phenomena inside a spiral wrap module.
Overall, the UTDR technique and its use in monitoring devices have a major impact
in the membrane industry due to its extremely powerful capabilities. / AFRIKAANSE OPSOMMING: Membraan-bevuiling of -verstopping is die grootste struikelblok wat die algemene
aanwending van membrane vir verskillende watersuiweringsprosesse negatief
beinvloed. 'n Beter begrip van membraan-bevuiling, asook beter metingsmetodes
daarvan is nodig om op bestaande skoonmaaktegnieke te verbeter.
Die hoofdoel van hierdie studie was die ontwikkeling van 'n nie-destruktiewe-in-lyn
visuele tegniek vir die meting van konsentrasie polarisasie en membraan-bevuiling.
Deur gebruik te maak van ultrasoniese klank golwe, is 'n tegniek ontwikkel wat 'n
direkte visuele aanduiding kon gee van die toestand van membraan-bevuiling binnein
die module.
'n Reghoekige aluminium-module, 24 cm lank, is ontwerp en gebou waarbinne die
membraan geplaas is vir die skeidingsproses. Resultate dui daarop dat daar 'n
uitstekende verband bestaan tussen die afname in permeaatvloei en die ultrasoniese
eggo vanaf die membraan. Die ultrasoniese tegniek kon die vorming van en toename
in membraan-bevuiling doeltreffend karakteriseer. In teenstelling hiermee, is die
tegniek ook suksesvol aangewend om die skoonmaak-proses van membrane te
ondersoek. Met min of geen data beskikbaar vir die skoonmaak-proses van
membrane in die industriële sektor, het die tegniek enorme potensiaal in die
optimisering van bestaande skoonmaak-tegnieke.
Die tegniek is verder aangewend op 'n industriële 8-duim deursnee spiraal-module
en goeie resultate is verkry. Stagnante sones asook vloed-vloei-patrone binne-in die
module kon suksesvol bepaal word. Baie navorsing is egter nog nodig om die
ingewikkelde data wat gegenereer word tydens die ondersoek van 'n spiraal-module
ten volle te verstaan.
Die enorme potensiaal en moontlikhede van die ultrasoniese tegniek kan die begin
wees van 'n revolusie in die membraan-industrie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52042 |
| Date | 12 1900 |
| Creators | Koen, Louis Johannes |
| Contributors | Sanderson, R. D., Lorenzen, L., Stellenbosch University. Faculty of Engineering. Dept. of Process engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 144 pages : illustrations |
| Rights | Stellenbosch University |
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