Thesis (MScEng (Chemical Engineering))--University of Stellenbosch, 2001. / 304 leaves single sided printed,preliminary pages i-xxii and numberd pages 1-282. Includes bibliography,list of figures and tables, used a Bizhub 250 Scanner to pdf format (OCR) 57pages contain figures in color.Digitized at 300 dpi 24-bit Color to pdf format (OCR),used a Hp Scanjet 8250 / ENGLISH ABSTRACT: Ecosystems and natural water sources are constantly under threat from
pollutants and all efforts should be made to minimise polluting factors. In the
last decade growing concern has been expressed with regard to the
environmental threat posed by wastewater produced by wineries and
distilleries. Research into winery wastewater commenced in the early nineties
mainly in Australia and France. These investigations characterised winery
wastewater, indicating a large diversity in quality and quantity between
wastewaters emanating from wineries. Owed to changes in South African
legislation, in conjunction with an augmented environmental awareness, the
need for an environmental assessment of wineries became apparent. In
South Africa, research of this nature had not yet been conducted. Previous
research on winery wastewater treatment employed mostly biological
technologies, with success but also shortfalls.
In South Africa the majority of wineries are located in the Western Cape
Province, several within the same water catchment area. Wineries may
produce approximately 1 to 10 litres of wastewater per litre of wine produced,
which are turbid and acidic and typically contain high levels of organic
compounds (thus oxygen deficient), and suspended material. Usually these
wastewaters are irrigated onto land, in close proximity to natural water
resources. The pollution of water tables and down-stream water sources may
occur. The quantification, qualification and treatment of this type of
wastewater are addressed in this study.
Winery wastewater produced from the predominantly red wine producing
Rupert and Rothschild Vignerons, served as case study for a two-year
wastewater audit strategy. The most common analyses performed on winery
wastewater include the Chemical Oxygen Demand (COD), suspended solids
(SS), pH and turbidity. A thorough analysis in the form of a comprehensive
audit was performed on the water and vinification processes. This allowed for
an accurate determination of contamination sources and properties. The audit
entailed a designed sampling protocol, the format of which was tailored as an
initial environmental assessment for the development of an Environmental
Management System (EMS) unique to Rupert and Rothschild Vignerons. The
EMS includes projected future objectives for wastewater quality (COD, SS,
pH, turbidity), as well as an environmental policy. In order to reach the
proposed quality objectives, a suitable wastewater treatment system must be
installed.
The efficiency of the treatment system present at Rupert and Rothschild
Vignerons was evaluated and piloted the investigation of physico-chemical
treatment technologies. Research into the applicability of induced
sedimentation (coagulation) and chemical oxidation (ozone) was the first of
its kind for winery wastewater as substrate, and provided an interesting
dimension in the sense of pragmatic and economic feasibility.
Dissolved and suspended particles present in winery wastewater do not settle
by gravity alone, thus requiring sedimentation agents (coagulants). Benchscale
experiments were conducted employing four types of pre-polymerised
metal salt coagulants (polyaluminium chloride). Successful sedimentation of
turbidity inducing compounds (up to 98 %) and suspended solid fractions (up
to 92%) was achieved. These coagulants are highly suitable for the treatment
of winery wastewater since the investigation showed that they are effective
over a broad pH and dosage range. In addition, rapid sedimentation rates
were observed, favouring thickener design economy.
Ozone is a potent oxidising agent, and has been reported to increase the
biodegradability of dissolved organic compounds and result in the decolouring
of wastewaters. Ozonation is highly pH dependent, with hydroxyl radical
activity dominating at alkaline pH. In the majority of gas-liquid contacting
systems, the kinetics of the heterogeneous reaction is not limited by the
chemical reaction rate, but by the transport of ozone to the liquid phase. To
compensate, the ozone concentration in the gas phase is increased. Coupled
to the primary investigation on the applicability of ozone treatment for winery
wastewater, thus emerged a secondary investigation into an enhanced mass
transfer system, realised by the use of impinging stream technology. The
ozone transfer in a conventional bubble-column was compared to that of an
impinging-stream jet-reactor. The latter significantly improved the ozone
transfer to the winery wastewater, resulting in the rate-limiting step being the
chemical reaction rate. Ozonation resulted in the increased biodegradability
of the winery wastewater, and complete colour and odour elimination.
Concerning jet-reactors, the principal importance lies in the substantial
reduction in the initial ozone concentration requirement, thereby rendering the
process more economically feasible.
Following the investigation of the wastewater dynamics, the determination of
eco-toxicology during irrigation should be conducted in future. When
considering induced sedimentation, further studies should be directed towards
ascertaining the most economic yet efficient dosage of the coagulant.
Similarly, a study concerning the economic viability of ozone efficiency should
be realised in terms of the energy requirements for both ozone generation and
the operation of jet-reactors. Although the jet reactor poses a benefit for
enhanced mass transfer, the essential criterion concerning residence time in
the reactor must be addressed for positive results.
Since no single solution exists for the treatment of winery wastewaters, the
application of the considered technology must be carefully selected and
incorporated in a treatment design; the two foremost criteria for selection
being efficiency and economy. / AFRIKAANSE OPSOMMING: Ekologiese stelsels en natuurlike waterbronne word gedurig bedreig deur
besoedeling, dus moet ten aile tye gepoog word om besoedeling te
minimiseer of te voorkom. Gedurende die laaste dekade is al hoe meer
kommer uitgespreek oor die besoedeling van afloop water afkomstig van wyn
en spiritualiee-vervaardiging. Navorsing aangaande wynafloopwater het
ontstaan in die vroee negentigs, hoofsaaklik in Australie en Frankryk. Hierdie
navorsing het gelei tot die karakterisering van wynafloopwater, en die
uiteenlopendheid van hierdie water aangaande die kwaliteit en kwantiteit
tussen kelders, is aangetoon. As gevolg van veranderinge in die SuidAfrikaanse
wetgewing, asook 'n groeiende bewuswording van omgewingsake,
het die noodsaaklikheid van omgewings impak-studies vir wynkelders na vore
getree. Tot op hede is navorsing van hierdie aard nog nie in Suid Afrika
gedoen nie. Vorige navorsing op die behandeling van wynafloopwater het
meestal biologiese tegnologiee behels, met 'n mate van sukses maar ook met
tekortkominge.
Die meederheid wynkelders in Suid Afrika is in die Wes-Kaap gelee, baie
binne dieselfde opvanggebied. Wynkelders kan tussen 1 tot 10 liter afloop
water produseer per liter wyn geproduseer. Hierdie afloop het tipies 'n hoe
konsentrasie organiese stowwe (is dus arm aan suurstof), is troebel en suur,
en bevat gesuspendeerde materiaal. Gewoonlik word die wynafloop water
besproei in die nabyheid van natuurlike waterbronne. Die besoedeling van
watertafels en waterbronne kan dus plaasvind. Die kwantifisering,
kwalifisering en behandeling van wynafloopwater word ondersoek in hierdie
tesis.
Die wynafloopwater van die hoofsaaklik rooiwyn produserende Rupert en
Rothschild Vignerons, het gedien as proefstudie tydens 'n twee-jaar
wynafloopwateroudit. 'n Deeglike analise in die formaat van 'n
veelomvattende oudit is uitgevoer op die wynmaakproses en die
waterafvoerstrome. 'n Akkurate bepaling van die oorsprong van
waterkontaminasie, asook die eienskappe daarvan is bewerkstellig. Die oudit
behels 'n spesifiek ontwerpte monsternemingprotokol, waarvan die formaat
geformuleer is om te dien as 'n beginpunt vir die ontwikkeling van 'n
Omgewingsbestuurstelsel (08S), uniek vir Rupert en Rothschild Vignerons.
Hierdie 08S sluit toekomstige doelstellings vir die kwaliteit (chemiese
suurstofbehoefte, gesuspendeerde vaste stowwe, pH, turbiditeit) van
wynafloopwater in, asook 'n omgewingsbeleid. Die installering van 'n
waterbehandelingsisteem moet geskied om te voldoen aan hierdie
voorgestelde doelstellings.
Die effektiwiteit van die huidige behandeling sisteem teenwoordig by Rupert
en Rothschild Vignerons is geevalueer en het gelei tot navorsing oor fisieschemiese
behandelingstegnologiee. Navorsing aangaande die toepassing
van geinduseerde sedimentasie (koagulasie) en chemiese oksidasie (osoon),
is vir die eerste keer toegepas op wynafloopwater, en het interessante
gevolge in 'n pragmatiese en ekonomiese sin.
Opgelosde en gesuspendeerde partikels teenwoordig in wynafloopwater sak
nie onder normale gravitasie uit nie, en dus word die toediening van
sedimentasie-induserende middels benodig. Eksperimente is in die
laboratorium uitgevoer met vier verskillende gepolimeriseerde
metaalsoutkoagulante (poli-aluminiumchloriedes). Dit het gelei tot die
effektiewe sedimentering van stowwe wat troebelheid (turbiditeit) veroorsaak
(tot 98 %) en ook gesuspendeerde stowwe (tot 92 %). Dit is gevind dat
hierdie tipe koagulante hoogs geskik is vir die behandeling van wynafloop
water, aangesien hulle effektief is by 'n wye pH- en doseringsreeks. Die
uitsaktempo is vinnig, wat dus die ontwerp van 'n uitsaktenk (verdikker)
ekonomies maak.
Osoon is 'n sterk oksideermiddel, terwyl talle verslae aandui dat dit die
biologiese ontbinding van opgelosde stowwe verhoog en die ontkleuring van
afloopwaters tot. gevolg het. Osonering is pH afhanklik; by alkaliese pH
oorheers die werking van hidroksielradikale. In die meerderheid gasvloeistofkontaksisteme
word die kinetika van die heterogene chemiese
reaksie nie beperk deur die intrinsieke reaksietempo nie, maar deur die
vervoer van osoon na die vloeistoffase. Om te kompenseer hiervoor, word die
osoon konsentrasie in die gasfase verhoog. Gekoppel aan die primere
ondersoek aangaande die toepasbaarheid van osoonbehandeling op
wynafloopwater, het 'n tweede ondersoek onstaan aangaande verhoogde
massa-oordragssisteme deur die gebruik van hoeintensiteit spuitreaktore. Die
osoonoordrag in konvensionele borrelkolomme is vergelyk met die van 'n hoe
intensiteit spuitreaktor. Laasgenoemde het die osoonoordrag na die
wynafloopwater aansienlik verhoog, met die gevolg dat die chemiese reaksie
die beperking op die reaksie tempo geplaas het. Osonering het die
biodegradasie van die wynafloop water verhoog, asook die kleur en reuk
verwyder. By die spuit-reaktor Ie die belangrikheid daarin by die aansienlike
veriaging in die aanvanklike behoefte aan osoonkonsentrasie, derhalwe is
hierdie oordragsisteem meer ekonomies.
Na afloop van die ondersoek op die dinamika van wynafloopwater, moet die
ekotoksisiteit gedurende besproeiing bepaal word vir toekomstige doeleindes.
Indien ge"induseerde sedimentasie verlang word, kan verdere studie gedoen
word om die mees ekonomiese dosis van die koagulant te bepaal.
Ooreenstemmend, moet die ekonomiese lewensvatbaarheid van die osoon
effektiwiteit bepaal word ten opsigte van die energiebehoefte van beide die
osoongenerasie en die werking van die hoe-intensiteit spuitreaktor. Alhoewel
die spuitreaktor verhoogde massa-oordrag bewerkstellig, moet die effek van
die residensietyd in die reaktor inag geneem word word ten einde positiewe
resultate te verkry.
Geen enkele oplossing bestaan vir die behandeling van wynafloop water nie,
derhalwe moet die toepassing van die beoogde sisteem versigtig gekies word
en ingesluit word in die ontwerp van 'n behandelingsisteem; die twee
vernaamste maatstawwe is ondermeer effektiwiteit en ekonomiese aspekte.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4586 |
| Date | 03 1900 |
| Creators | Marais, Dulcie |
| Contributors | Lorenzen, L., University of Stellenbosch. Faculty of Engineering. Dept. of Process Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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