Thesis (MSc Food Sc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: South Africa is a developing country that relies on its agricultural sector as a main source of overall
economic welfare. Development does not only give rise to new technology and new products but
also results in increased amounts of liquid and solid waste.
Generally, the production of wine is considered an environmentally friendly process, but
significant amounts of natural resources and organic amendments are necessary, while generating
large amounts of liquid and solid wastes. Anaerobic digestion (AD) is an attractive and proven
treatment option for both liquid and solid wastes as valuable products and depollution can be
obtained. AD of liquid waste results in an effluent and biogas, while anaerobic composting of solid
waste results in an organic amendment, leachate and biogas.
The overall objective of this study was to investigate the operational feasibility of the cotreatment
of leachate produced during the anaerobic composting (AnC) of grape skins in an upflow
anaerobic sludge blanket (UASB) reactor while treating winery wastewater. This first aim of this
study was to investigate the efficiency of the anaerobic composting of grape skins. Laboratoryscaled
digesters (1L) were utilised as anaerobic composting units. The most important operational
parameters were identified (pH, moisture content and inoculum (size, ratio, composition)) in order
to produce a pH stable, odour free compost in 21 days.
Experimental studies highlighted the importance of shredding waste as well as the addition
of calcium oxide and green waste to increase the initial pH of the composting mixture. After
optimising a 50% (m.m-1) cow manure inoculum, lower inoculum concentrations (10, 15 and 25%
(m.m-1)) were investigated to make the process more economically viable. A 10% (m.m-1)
anaerobic compost (AC) inoculum was found to produce the most favourable results in terms of pH
stabilisation and leachate generation. A 50% (m.m-1) moisture level performed the best by
attaining a pH > 6.5 on day 6 and having the highest end pH (7.65) on day 21, while white and red
grape skins in an equal ratio were found to generate a higher end pH. With all these optimum
parameters in place (shredded waste, green waste, CaO, inoculum, moisture, grape skins), a
compost with a final pH (7.09), moisture (58%), nitrogen (2.25%), phosphorous (0.22%) and
potassium content (1.7%) was obtained. The optimised parameters were scaled-up (1:10) by
using polyvinyl chloride anaerobic digesters (20 L) to suit the operational requirements of the AnC
process and also produced a stable compost within 21 days. The second aim of this study was to investigate the combined anaerobic digestion of winery
wastewater (WWW) and leachate obtained from the anaerobic composting of grape skins in an
upflow anaerobic sludge blanket (UASB). This involved the operation of a 2.3 L laboratory-scale
UASB reactor for 205 days. The reactor successfully co-treated WWW and leachate at
ca. 8.5 kgCOD.m-3d-1 with a final chemical oxygen demand (COD) reduction of over 90%, a stable
reactor effluent pH (7.61) and alkalinity (3 281 CaCO3 mg.L-1). This study showed the feasibility
for the combined treatment of liquid and solid waste from the winemaking process. Although the legal limits for reactor effluent disposal onto land was not met, significant reduction in COD
concentrations were achieved, whilst producing a soil amendment that could potentially result in
cost savings for chemical fertilisers. The benefits related to using anaerobic bioconversion as a
treatment option for liquid and solid waste could possibly be advantageous to the wine industry as
an environmental control technology, by converting liquid and solid waste into valuable resources. / AFRIKAANSE OPSOMMING: Suid-Afrika is 'n ontwikkelende land wat staatmaak op sy landbousektor as 'n hoofbron van
algehele ekonomiese welstand. Ontwikkeling gee nie net aanleiding tot nuwe tegnologie en nuwe
produkte nie, maar lei ook tot die verhoogde bydrae van vloeistof sowel as vaste afval.
Oor die algemeen, word die produksie van wyn beskou as 'n omgewingsvriendelike proses,
maar aansienlike hoeveelhede natuurlike hulpbronne en organiese kunsbemesting word benodig,
terwyl groot hoeveelhede vloeistof en vaste afval gegenereer word. Anaërobiese vertering (AV) is
'n aantreklike en bewese behandelingsopsie vir beide vloeistof en vaste afval aangesien
waardevolle produkte en suiwering verkry kan word. AV van vloeistowwe lewer uitvloeisel sowel
as biogas, terwyl anaërobiese kompostering van vaste afval 'n organiese kunsbemesting, loog en
biogas lewer.
Die oorhoofse doel van hierdie studie was om die operasionele doeltreffendheid van die
mede-behandeling van loog wat gegenereer word tydens die anaërobiese kompostering (AnK) van
druiwe doppe in 'n opvloei-anaërobiese-slykkombers (OAS) reaktor terwyl kelderafvalwater
behandel word, te ondersoek. Die eerste mikpunt van hierdie studie was om die doeltreffendheid
van die anaërobiese komposteringsproses van druiwe doppe te ondersoek. Laboratorium-skaal
verteerders (1L) is gebruik as anaërobiese komposteringseenhede. Die belangrikste operasionele
parameters is geïdentifiseer (pH, voginhoud en inokulum (grootte, verhouding, samestelling)) om ‘n
'n pH-stabiele, reukvrye kompos te produseer in 21 dae. Die belangrikheid van gesnipperde afval asook die byvoeging van kalsiumoksied en groen
afval om die aanvanklike pH van die komposmengsel te verhoog, is deur eksperimentele studies
beklemtoom. Na die optimering van 'n 50% (m.m-1) koeimis inokulum, is laer inokulum
konsentrasies (10, 15 en 25% (m.m-1)) geondersoek om die proses meer ekonomies uitvoerbaar te
maak. Daar is gevind dat ‘n 10% (m.m-1) anaërobiese kompos (AK) inokulum die mees gunstige
resultate lewer in terme van pH stabilisering en loog generering. ‘n 50% (m.m-1) vloeistof vlak het
die beste presteer deur 'n pH> 6.5 te bereik teen Dag 6 asook die hoogste eind pH (7.65) teen Dag
21, terwyl wit en rooi druiwe doppe in dieselfde verhouding gevind is om ‘n hoër eind pH te
genereer. Met al hierdie optimum parameters in plek (gesnipperde afval, groen afval,
kalsiumoksied, inokulum, vog, druiwe doppe) is 'n kompos met 'n finale pH (7.09), vog (58%),
stikstof (2.25%), fosfor (0.22%) en kalium inhoud (1.7%) verkry. Die optimale parameters is
opgeskaal (1:10) deur gebruik te maak van polivinielchloried anaërobiese verteerders (20 L) om
aan die operasionele vereistes van die AnK proses te voldoen en ook om 'n stabiele kompos binne
21 dae te produseer.
Die tweede mikpunt van hierdie studie was om die gekombineerde anaërobiese vertering
van kelderafvalwater en loog, verkry vanaf die anaërobiese kompos van druiwe doppe in 'n OAS
reaktor, te ondersoek. Dit het die bedryf van 'n 2.3 L laboratorium-skaal OAS reaktor vir 205 dae
ingesluit. Die reaktor het kelderafwater en loog suksesvol behandel by ongeveer 8.5 kgCSV.m-3d-1
met 'n finale chemiese suurstof vereiste (CSV) vermindering van meer as 90%, 'n stabiele reaktor
uitvloeisel pH (7.61) en alkaliniteit (3 281 CaCO3mg.L-1). Hierdie studie het die uitvoerbaarheid
van die gekombineerde behandeling van vloeistof en vaste afval van die wynmaakproses getoon.
Alhoewel die wetlike vereistes van die reaktor uitvloeisel vir storting op grond nie bereik is nie, is ‘n
beduidende vermindering in CSV konsentrasies bereik, asook die vervaardiging van
kunsbemesting wat die potensiële aankoopkoste van chemiese kunsmis kan verminder. Die
voordele verbonde aan die gebruik van anaërobiese bio-omskakeling as 'n behandelingsopsie vir
vloeistof en vaste afval kan moontlik voordelig wees vir die wynbedryf as 'n omgewingsbeheerende
tegnologie deur om vloeistof en vaste afval om te skakel na waardevolle bronne.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/96771 |
| Date | 18 February 2015 |
| Creators | de Kock, Michelle |
| Contributors | Sigge, Gunnar Oliver, Britz, Trevor Johannes, Stellenbosch University. Faculty of Agrisciences. Dept. of Food Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xiv, 144 pages : colour illustrations |
| Rights | Stellenbosch University |
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