Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Large volumes of wastewater are generated annually during the grape harvest season from
various processing and cleaning operations at wineries, distilleries and other wine-related
industries. South African regulatory bodies dictate that wastewater should have a pH of 5.5
to 7.5 and a chemical oxygen demand (COD) lower than 75 mg/L. However, winery
wastewater has a typical pH of 4 to 5 and a COD varying between 2 000 and 12 000 mg/L.
Urban wineries channel the wastewater to local sewage treatment facilities and are often
heavily fined for exceeding governmental requirements. Rural wineries usually have little
or no treatment operations for their wastewater and it is often irrigated onto crops, which
may result in environmental pollution and contamination of underground water resources.
Various criteria are important in choosing a wastewater treatment system, such as an ecofriendly
process that is flexible to withstand various concentration loads and characteristics,
requiring low capital and operating costs, minimal personal attention and do not require too
much land. In this study, a large variation in COD, pH and chemical composition of the
winery wastewater was observed that could be related to varying factors such as the harvest
load, operational procedures and grape variety. Wastewater from destemming and pressing
operations contained higher concentrations of glucose, fructose and malic acid, which
originated from the grape berries. The fermentable sugars (glucose and fructose)
contributed to almost half of the COD with a smaller contribution from ethanol and acetic
acid. The low pH can be ascribed to relative high concentrations of organic acids in the
wastewater.
The efficacy of biological treatment systems depends strongly on the ability of
microorganisms to form biofilm communities that are able to degrade the organic
compounds in the wastewater. Preliminary identification of microorganisms that naturally
occur in winery wastewater indicated the presence of various bacterial and yeast species that
could be effective in the biological treatment of the wastewater. When evaluated as pure
cultures under aerobic conditions, some of the yeast isolates effectively reduced the COD of
a synthetic wastewater, whereas the bacterial isolates were ineffective. The most effective
yeast isolates were identified as Pichia rhodanensis, Kloeckera apiculata, Candida krusei
and Saccharomyces cerevisiae. Our search for cost-effective biological treatment systems led to the evaluation of a Rotating
Biological Contactor (RBC) for the treatment of winery wastewater. The RBC was
evaluated on a laboratory scale with 10% (v/v) diluted grape juice and inoculated with a
mixed microbial community isolated from winery wastewater. The results showed a
reduction in the COD that improved with an extended retention time. Evaluation of the
RBC on-site at a local winery during the harvest season resulted on average in a 41%
decrease in COD and an increase of 0,75 pH units.
RFLP analysis of the biofilm communities within the RBC confirmed a population shift in
both the bacterial and fungal species during the evaluation period. The most dominant yeast
isolates were identified with 18S rDNA sequencing as Saccharomyces cerevisiae, Candida
intermedia, Hanseniaspora uvarum and Pichia membranifaciens. All these species are
naturally associated with grapes and/or water and with the exception of Hanseniaspora
uvarum, they are able to form either simple or elaborate pseudohyphae. / AFRIKAANSE OPSOMMING: Groot hoeveelhede afloopwater word jaarliks gedurende die druiwe-oestyd deur verskeie
prosessering- en skoonmaakoperasies deur wynkelders, distilleer- en ander wynverwante
industrieë gegenereer. Suid-Afrikaanse beheerliggame vereis dat afloopwater ‘n pH van 5.5
tot 7.5 en ‘n chemiese suurstofbehoefte (COD) van minder as 75 mg/l moet hê.
Kelderafloopwater het egter gewoonlik ‘n pH van 4 tot 5 en ‘n COD van 2 000 tot 12 000
mg/L. Stedelike wynkelders voer die afloopwater na ń plaaslike rioolsuiweringsaanleg wat
dikwels tot swaar boetes vir oortreding van die wetlike vereistes lei. Plattelandse
wynkelders het gewoonlik min of geen behandelingsprosesse vir hul afloopwater nie en
gebruik die water dikwels vir gewasbesproeiing, wat tot omgewingsbesoedeling en
kontaminasie van ondergrondse waterbronne kan lei.
Verskeie kriteria is belangrik in die keuse van ‘n waterbehandelingstelsel, byvoorbeeld ‘n
omgewingsvriendelike proses wat verskillende konsentrasieladings en samestellings kan
hanteer, ‘n lae kapitaal- en bedryfskoste en minimale persoonlike aandag vereis en min
ruimte benodig. Hierdie studie het getoon dat kelderafloopwater ‘n groot variasie in COD,
pH en chemiese samestelling het wat met wisselende faktore soos die oeslading,
operasionele prosesse en selfs die druifkultivar verband kan hou. Afloopwater van
ontstingeling- en parsoperasies het hoër konsentrasies glukose, fruktose en appelsuur wat
van die druiwekorrels afkomstig is. Die fermenteerbare suikers (glukose en fruktose) dra tot
amper 50% van die COD by, met ‘n kleiner bydrae deur etanol en asynsuur. Die lae pH kan
grootliks aan organiese sure in die afloopwater toegeskryf word.
Die effektiwiteit van biologiese behandelingstelsels steun sterk op die vermoë van mikroorganismes
om biofilmgemeenskappe te vorm wat die organiese verbindings in die
afloopwater kan afbreek. Voorlopige identifikasie van mikro-organismes wat natuurlik in
wynafloopwater voorkom, het die teenwoordigheid van verskeie bakteriese en gisspesies
aangedui. Evaluering van hierdie isolate onder aërobiese toestande het getoon dat sommige
van die gis-isolate die COD van ‘n sintetiese afloopwater effektief kon verlaag, terwyl die
bakteriese isolate oneffektief was. Die mees effektiewe gis-isolate is as Pichia rhodanensis,
Kloeckera apiculata, Candida krusei en Saccharomyces cerevisiae geïdentifiseer. Ons soektog na ‘n koste-effektiewe biologiese behandelingsisteem het tot die evaluering van
‘n ‘Rotating Biological Contactor’ (RBC) vir die behandeling van afloopwater gelei. Die
RBC is op laboratoriumskaal met 10% (v/v) verdunde druiwesap geëvalueer en met ‘n
gemengde mikrobiese gemeenskap wat uit afloopwater geïsoleer is, innokuleer. Die
resultate het ‘n verlaging in die COD getoon wat met ‘n langer retensietyd verbeter het.
Evaluering van die RBC by ‘n plaaslike wynkelder gedurende die oesseisoen het gemiddeld
‘n verlaging van 41% in die COD en ‘n verhoging van 0,75 pH eenhede getoon.
RPLP analise van die biofilmgemeenskappe in die RBC het ‘n bevolkingsverskuiwing in
beide die bakteriese en swamspesies aangetoon. Die mees dominante gisspesies is met 18S
rDNA volgordebepaling as Saccharomyces cerevisiae, Candida intermedia, Hanseniaspora
uvarum en Pichia membranifaciens geïdentifiseer. Al hierdie spesies word gewoonlik met
druiwe en/of water geassosieer en is, met die uitsondering van Hanseniaspora uvarum, in
staat om òf eenvoudige òf komplekse pseudohife te vorm.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/16385 |
| Date | 04 1900 |
| Creators | Malandra, Lida,1975- |
| Contributors | Bloom, M., Wolfaardt, G.M., University of Stellenbosch. Faculty of Science. Dept. of Microbiology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | vii, 77 leaves : ill. |
| Rights | University of Stellenbosch |
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