anaerobic bioconversion of liquid and solid wastes from the winemaking process

159 Pages·2015·2.96 MB·English

ANAEROBIC BIOCONVERSION OF LIQUID AND SOLID
WASTES FROM THE WINEMAKING PROCESS
Michelle de Kock
Thesis presented in partial fulfilment of the requirements for the degree of
Master of Science in Food Science
Department of Food Science
Faculty of AgriSciences
Stellenbosch University
Supervisor: Dr. G.O. Sigge
Co-supervisor: Prof. T.J. Britz
March 2015
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DECLARATION

By submitting this thesis electronically, I declare that the entirety of the work contained therein is
my own, original work, that I am the sole author thereof (save to the extent explicitly otherwise
stated), that reproduction and publication thereof by Stellenbosch University will not infringe any
third party rights and that I have not previously in its entirety or in part submitted it for obtaining any
qualification.

Michelle de Kock Date

Copyright © 2015 Stellenbosch University
All rights reserved
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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 co-
treatment 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. Laboratory-
scaled 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 CaCO mg.L-1). This study showed the feasibility
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for the combined treatment of liquid and solid waste from the winemaking process. Although the
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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.
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UITTREKSEL

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
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met 'n finale chemiese suurstof vereiste (CSV) vermindering van meer as 90%, 'n stabiele reaktor
uitvloeisel pH (7.61) en alkaliniteit (3 281 CaCO mg.L-1). Hierdie studie het die uitvoerbaarheid
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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.
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ACKNOWLEDGEMENTS

Endless gratitude and thanks for both support and encouragement are shown to the following
people and institutions for their invaluable contribution to this study:

My supervisor, Dr G.O. Sigge who made it possible for me to work on a topic that I have a great
interest in. His generous guidance, expertise, constructive support, encouragement and
understanding throughout this study are greatly appreciated;

My co-supervisor, Prof. T.J. Britz for being a mentor, an educator, a food scientist and a
microbiologist by heart. His endless enthusiasm and expertise in anaerobic digestion is an
inspiration to all. It has been an honour and a privilege to work with both of them;

Vice-Rectors Research Discretionary Fund for financial contribution towards this study;

The National Research Foundation for providing me with the NRF Scarce Skills bursary;

Jacques Blignaut and Gerald van Rooyen from Distell for providing me with winery wastewater
samples as often as required. Special thank you to Gerald for assistance during the collection and
sampling of heavy wastewater containers;

Francois Conradie from Muratie Wine Estate for kindly providing me with grape skins as often as I
needed it; as well as providing me with any information regarding the winemaking process;

Sas Basson from Delheim for also providing me with grape skins;

Dr Paul Williams, Anchen Lombaard and Mr. Chisala Ng’Andwe for encouragement, advice and
humour especially during tea time breaks;

Dr. Corné. Lamprecht for inspiration and providing valuable advice throughout this study;

Daleen du Preez, for support, encouragement, coffee breaks and help with any administrative
duties;

Petro du Buisson and Veronique Human for motivation, help and information regardless of the time
and day;
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Eben Brooks for assistance with lab equipment and sampling, general interest in this project as
well as supplying humour during times of need;

Mr. John Achilles for help over weekends with sampling drums and the ice machine;

My first and second year lab partners, amazing friends and seating area companions: Nika, Alet,
Louise, Marlize, Madelizé, Custodia, Marco, Wendy, Kirsty, Carmen, Francois, Marilet, and Adél.
Thank you for your support, encouragement, love, laughter and giving me some of the best
memories of my life;

My friends and most favourite human beings: Séan, Bastian, Marlize, and Melanie. Thank you for
your unwavering support and encouragement throughout this study, getting up early on weekends
to accompany me to do lab work, for your interest in this project, your love, and supplying me with
unlimited amounts of laughter. I am very lucky to count you as my friends;

My sister, Nicky de Kock for assistance with drawings, and for motivation especially during the last
few weeks of this study;

My parents, Elsabé and Eddy for always supporting me, believing in me and encouraging me. I
could not have done it without you.
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To my parents, for a lifetime of love and support
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TABLE OF CONTENS
Chapter Page

Abstract ii
Uittreksel iv
Acknowledgements vi
Dedication viii

List of figures x
List of tables xii
List of abbreviations xiii

Chapter 1 Introduction 1

Chapter 2 Literature review 6

Chapter 3 Determining optimum operational parameters for 87
anaerobic composting of grape skins

Chapter 4 Co-treatment of leachate produced during the 123
anaerobic composting of grape skins in an upflow
anaerobic sludge blanket reactor treating winery
wastewater

Chapter 5 General discussion and conclusions 140

This thesis is presented in the format prescribed by the Department of Food Science at
Stellenbosch University. The structure is in the form of one or more research chapters (papers
prepared for publication) and is prefaced by an introduction chapter with the study objectives,
followed by a literature review chapter and culminating with a chapter for elaborating a general
discussion and conclusion. Language, style and referencing format used are in accordance with
the requirements of the International Journal of Food Science and Technology. This thesis
represents a compilation of manuscripts where each chapter is an individual entity and some
repetition between chapters has, therefore, been unavoidable.