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Application of water pinch to an integrated pulp and paper Kraft mill with an already highly closed water system.January 2009 (has links)
Sappi's Ngodwana integrated Kraft pulp and paper mill was used as case study for the application and
evaluation of the water pinch technique. The technique of water pinch originates from energy pinch, but
uses mass flow and contaminant concentration to identify water and effluent reduction opportunities.
The classical meaning of pinch, as defmed by energy pinch has however been changed to a more
modem meaning. Historically the terms water or energy pinch was used to refer to the points where two
composite curves touched on energy or water graphs. This graphical meaning of pinch is gradually
being replaced to refer to the optimal po int proposed by a numerical solver beyond which improvement
of the water network is no longer possible for the given inputs. The water pinch technique was applied
by means of a numerical solver that used mixed integer non-linear programming to optimise to the
minimum cost for running the water network under investigation. The problem defmition was defined
in terms of costs associated with the use of utilities, raw material, treatment facilities and process units.
It was also possible to define factors such as environmental impact, corrosion, fouling, scaling, cooling
tower treatment cost, legal risk etc in terms of a penalty cost. The water pinch technique has been
refined in software packages that are user friendly, ca~ble of handling multi-contaminants and suitable
for varying flows. The software package WaterPinch by Linnhoff March was used. The case study
was applied on Ngodwana mill that has an already highly closed water system with effluent generation
rates as low 20 kL per ton of pulp and paper. The pinch study included sodium, chloride, calcium,
suspended solids and COD as contaminants. The study investigated different applications of the pinch
technique. The following was concluded:
• The mill's understanding of its current restrictions, ()l pinch points, of its water network was
confirmed. No new pinch points have been identified of which the mill was not aware. This
indicates that the mill was already highly knowledgeable about its water system. This was expected
of a mill that has a very low specific-effluent-generation rate. Water pinch was unable to
significantly improve on the effluent generation rate of the mill.
• The pinch analysis has identified opportunities of mixing small quantities of waste streams into
process water streams to replace fresh water. These changes can introduce minor water savings and
new risks to the process that have to be understood better before implementation.
• The mill has progressed far with the design and costing of a proposed effluent treatment plant
(ERPl). The integration of this treatment plant into the water network was investigated using the
pinch technique. The pinch solver suggested a totally different approach to the integration of the
ERPI plant compared to design of the mill. The mill's design revolves around the treatment of low
chloride streams in the ERPl plant and using of the treated water as make-up to the cooling towers.
Sodium was recovered as raw material from the cooling towers' blow-down. Pinch proposed
treatment of the high cWoride containing streams and returning the streams to users suitable of using
high chloride water. The network proposed by mill's design generates 8.2 MLlday effluent less
than the pinch proposal, and recovers sodium as raw material. The proposal presented by pinch is
not recommended and points to the difficulty in simulating factors, such as raw material recovery, in
a pinch analysis.
• Users for the excess storm water were identified using water pinch and will be suitable for
implementation. The mill has mwever decided on alternative sinks for the storm water based on
considerations such as process inter-dependency, risks associated with contamination and general
management philosophy for the different systems in the mill. These considerations could have been
included into the pinch solver, but were not because it was of interest what the second best option
would be.
• The pinch investigation proved useful to confirm certain understandings of the mill. The
investigation confirmed the difficulty of improving the water systems of the mill due to the fact that
Ngodwana is already a highly closed and integrated mill. Numerous smaller process changes have been identified by the pinch solver and could be investigated further for smaller process
improvements.
• It i; recommended that pinch technology be applied again when the mill plans to make major
process changes or expansions. It is also recommended to use water pinch on a more frequent basis
in smaller sections of the mill or for other evaluations in the mill. As a group Sappi could benefit
from the use of water pinch, especially in situations where the water network of the mill is not
already water efficient.
• The recommendations and conclusions in this report have not been subjected to technical and
economical feasibility studies. Extensive further studies must be conducted before implementation
of any of the results. Further studies must include impacts from process dynamics, long term
effects, impacts from other contaminants that have not been simulated, etc. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.
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Genetic and enzymatic characterisation of wood degrading strains of Phanerochaete speciesDe Koker, T. H. (Theodorus Hermanus), 1965- 03 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: White rot fungi are of interest in the paper and pulp industry because of their
removal of lignin from wood. In this study over 600 Basidiomycete fungi were
isolated from indigenous forests as well as from commercial Eucalyptus spp.
and Pinus spp. plantations in South Africa. One hundred isolates were
identified to genus level. Biochemical tests were done to screen the fungal
cultures for characteristics that are favourable for biopulping, e.g. low
cellulase activity with concomitant high activity of ligninolytic enzymes.
Various Phanerochaete isolates with potentially high ligninolytic activity were
identified.
Although Phanerochaete chrysosporium Burds. has previously been isolated
from the indigenous forest at Knysna in South Africa, this study showed that
P. chrysosporium was a natural coloniser of wood chip piles in South Africa,
indicating potential for application in industry. A possible new species of
Phanerochaete, viz. Phanerochaete pseudomagnoliae nom. provo (strain
PP25) from decayed wood collected in Stellenbosch, South Africa, was
described and illustrated. It differs from previously described Phanerochaete
species in having smaller basidiospares, and in the formation of few
chlamydospores on malt extract agar but more on xylose containing media.
The potential of using internal transcribed spacer DNA sequences (ITS) to
infer phylogenetic relationships among species of the genus Phanerochaete
was investigated. Consensus phylogenetic trees could be presented, but the
presence of ambiguous aligning sequences within the ITS made inferring of
phylogenetic relationships within the whole genus difficult.
Fifty-five South African strains of P. chrysosporium were screened for lignin
peroxidase (liP), manganese peroxidase (MnP) and glyoxal oxidase (GLOX)
enzymes. Manganese peroxidase activity was quantified on agar media. The
liP and GLOX activities of 13 selected strains, including control strains and
P. pseudomagnoliae (PP25), were also quantified on agar media. Differences
in MnP and GLOX activities existed among the strains. Preliminary
biochemical characterisation of strain PP25 indicated that the most important
difference was the apparent unique regulation of ligninolytic enzymes. Under
low nitrogen, liP activity of the selected strains showed no significant variation, whereas strain PP25 had significantly increased liP levels under
high nitrogen conditions. Restriction fragment length polymorph isms of the
lignin and manganese peroxidase gene DNA fragments showed variability
among strains, whereas there was probably only allelic variation for the glox
gene DNA fragments.
Previous research has indicated xylose oxidation activity within
P. chrysosporium. To investigate whether GLOX can oxidise xylose, a purified
recombinant GLOX (rGLOX) from P. chrysosporium BKM-F-1767 Burds. was
used in this study. This rGLOX oxidised D-xylose and D-glucose (D-xylose >
D-glucose) to produce H202. Xylose was oxidised to xylono-1 ,4-lactone with a
1:1 stoichiometric relationship between H202 produced and xylose used.
Xylono-1,4-lactone was converted non-enzymatically to xylonate. This
suggested that the furanose form of xylose, rather than the pyranose form, is
a substrate of GLOX. The production of H202 and the removal of inhibitory
compounds by GLOX could enhance ligninolytic activity. .
To conclude, unique strains of P. chrysosporium have been isolated from
South Africa with potential biotechnological use in paper manufacturing. The
relationship of P. pseudomagnoliae nom. provo to other Phanerochaete
species was evaluated and light was shed on the possible role of GLOX in
lignin degradation. / AFRIKAANSE OPSOMMING: Witvrot swamme is van belang vir die papier en pulp industrie omdat hulle
lignin vanaf hout kan verwyder. Meer as 600 Sasidiomiseet fungi, afkomstig
vanaf inheemse woude asook kommersiële Eucalyptus spp. en Pinus spp.
plantasies, IS geïsoleer. Een honderd isolate is tot op genusvlak
geïdentifiseer. Die isolate is biochemies vir eienskappe wat voordelig vir
"bioverpulping" kon wees, bv. die gelyktydige produksie van lae sellulosemaar
hoë ligninolitiese ensiemaktiwiteit, getoets. Verskeie isolate met
potensieel hoë vlakke van ligninolitiese aktiwiteit is verkry.
Alhoewel Phanerochaete chrysosporium Surds. vantevore in die Knysna
inheemse woud in Suid-Afrika geïsoleer is, het hierdie studie gewys dat
P. chrysosporium natuurlik op hope houtblokkies voorgekom, met moontlike
toepasing in die industrie. Isolaat PP25, geisoleer vannaf verrottende hout te
Stellenbosch, Suid Afrika, is as 'n potensieel nuwe spesie van die genus
Phanerochaete beskryf en as Phanerochaete pseudomagnoliae nom. provo
benoem. Hierdie isolaat verskil van ander Phanerochaete-spesies daarin dat
dit kleiner basidiospore vorm en nie klamydospore op moutekstrakagar
produseer nie, maar wel op media wat xilose bevat. Die potensiaal van intern
getranskribeerde spasieerder ONS opeenvolging vir die aflei van filogenetiese
verhoudings tussen spesies van die genus Phanerochaete is ondersoek.
Konsensus filogenetiese bome kon bepaal word, maar die teenwoordigheid
van varieerbare areas het die afleiding van filogenetiese verwantskappe vir
die hele genus bemoeilik.
Vyf-en-vyftig Suid-Afrikaanse isolate van P. chrysosporium is vir die
teenwoordigheid van lignienperoksidase- (liP), mangaanperoksidase- (MnP)
en glioksaaloksidase (GLOX)-aktiwiteit getoets. Vlakke van MnP-aktiwiteit is
op agarplate gekwantifiseer. Vlakke van LiP- en GLOX-ensieme op agarplate
is vir 13 geselekteerde isolate, insluitend kontroles en ras PP25,
gekwantifiseer. Aktiwiteit van MnP en GLOX het statisties betekenisvol tussen
isolate verskil. Lignienperoksidase-aktiwiteit onder lae stikstof toestande het
nie statisties betekenisvol van mekaar verskil nie. Onder hoë stikstof
toestande het isolaat PP25 wel verhoogde liP-aktiwiteit getoon. Restriksie
fragment polimorfismes van die lignien- en mangaanperoxidase-gene het variasie getoon, terwyl waarskynlik slegs alleliese variasie vir die glox geen
waargeneem IS.
Rekombinante GLOX (GLOX vanaf P. chrysosporium BKM-F-1767) het xilose
en glukose (D-xilose > D-glukose) geoksideer met meegaande produksie van
H202. Xilose is na xilono-1,4-laktoon geoksideer met 'n 1:1 stoigiometrie
tussen H202-produksie en xilose verbruik. Xilono-1,4-laktoon is nieensiematies
na xilonaat omgeskakel. Bogenoemde resultaat dui aan dat die
furanose vorm van xilose die werklike substraat vir GLOX is. Deur die
meegaande produksie van H202 en die verwydering van inhiberende produkte
word lignoliese aangehelp.
Ten slote, unieke P. chrysosporium rasse met potensiële gebruik in
papiervervaardiging is in Suid-Afrika geisoleer. Die genetiese diversiteit van 'n
nuwe spesie, P. pseudomagnoliae, is bepaal en nuwe lig is op die potensiële
rol van GLOX in lignienafbraak gewerp.
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Fungal pretreatment of unextracted and pressurized hot water extracted Eucalyptus Grandis wood chipsDyantyi, S. D. (Simphiwe David) 12 1900 (has links)
Thesis (MScFor)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Unextracted (control) and PHWe Eucalyptus grandis wood chips were pulped at 15% active
alkali (AA) and 1% antraquinone (AQ). Another batch of wood chips were then inoculated
with fungal co-cultures of Aspergillus flavipes and Pycnoporus sanguineus. FCCi wood chips
were incubated for four weeks; one PHWe inoculated experimental treatment was incubated
for three weeks. The full pulping cycle (160 min) was used to digest the experimental
treatments with the exception of one lot of PHWe wood chips that were pulped for 150
minutes. A further experimental treatment of PHWe wood chips was cooked at a reduced AA
charge of 14% and 1% AQ. Analysis of variance (ANOVA) of the data from all the
experimental treatments was conducted and the differences within the experimental treatments
were determined using Statistica (v7, 1984–2006). The F-value (Fischer distribution) and the
p-value as well as a non-parametric test known as the Mann-Whitney procedure was tested at
the 95% confidence limit. For a further enhancement of the 95% confidence limit the screened
yield data was tested by the Bootstrap method. Scanning electron micrographs clearly
demonstrated the changed structure and appearance of the chip cross-sectional area after the
different pretreatments.
Although the mean average results of all the screened pulp yields showed no significant
statistical difference (p> 0.05), differences in screened yield of up to 2.5% were obtained. All
the weighted means of the rejects showed a significant difference (p < 0.05). Other pulp
properties like shive content, chemical consumption, Kappa number, handsheet brightness and
strength tests showed mixed results i.e. rejected or accepted the hypothesis (p> or =or < 0.05).
The hypothesis that the combined PHWE and FCCI of wood chips would further increase the
pulp yield had to be rejected. It is however anticipated that the combination of PHWE with
successive co-culture fungal pretreatment would be very beneficial in obtaining higher pulp
yields for fully bleached chemical pulp. Further research would be required to test this
assumption. This investigation confirmed the expected beneficial effects of combined PHWE
and FCCI pretreatments of wood chips on the strength properties. In addition the combined
treatment also improved the initial bonding strength potential of the unbeaten fibres. / AFRIKAANSE OPSOMMING: Onbehandelde en met onder druk, warm water uitgeloogde Eucalyptus grandis houtspaanders
is respektiefwelik met 15% aktiewe alkali (AA) en 1% antrakinoon (AQ) verpulp. Hierdie is
dan met swamkokulture van Aspergillus flavipes en Pycnoporus sanguineus inokuleer en
respektiewelik vir drie en vier weke inkubeer. Onder druk uitgeloogde houtspaanders is ook
vir 150 minute verpulp by 15% AA 1% AQ en by ‘n verminderde AA van 14%.
Pulpevaluasies is uitgevoer op alle eksperimentele behandelinge. Alle onder druk uitgeloogde
en met swamkokultuur inokuleerde houtspaanders het ‘n laer pulpopbrengs, uitskot,
skilferinhoud, Kappanommer en ‘n hoër RAA en helderheid opgelewer in vergelyking met die
vars houtspaanders. Die vars en warm water uitgeloogde houtspaanders het soortgelyke
pulpopbrengs opgelewer.
‘n Variansieanalise (ANOVA) van die data van alle eskperimentele behandelings is uitgevoer
gebruikmakende van Statistica (V7, 1984 – 2006). Die F-waarde (Fischer-verspreiding) an die
p-waarde so wel as ‘n parametriese toets (Mann-Whitney prosedure) is getoets by ‘n 95%
betroubaarheidsgrens. Vir ‘n verdere verhoging van die 95% betroubaarheidsgrens van die
pulpopbrengs, is die beskikbare data weer getoets met die Bootstrap-metode.
Alle gemiddelde pulpopbrengswaardes het geen beduidende statistiese verkil opgelewer nie
(p>0.05), alhoewel verskille van tot 2.5% in pulpopbrengs verkry is. Alle gemiddelde
uitskotwaardes het ‘n beduidende verskil getoon (p<0.05). Die ander pulpeienskappe soos
skilferinhoud, verbruik aan chemikalieë, Kappagetal, handvel helderheid en sterktewaardes
het gemengde resultate opgelewer maw verwerping of aanvaarding van die hipotese p> or =or
< 0.05. Die hipotese dat die gekombineerde PHWE en FCCI van die houtspaanders die
pulpopbrengs verder sou verhoog moes verwerp word. Daar word egter verwag dat die
kombinasie van PHWE met opeenvolgende swamkokultuur behandeling baie voordelig sou
wees op die pulpopbrengs van ‘n ten volle gebleikte chemiese pulp. Verdere navorsing is
nodig om hierdie veronderstelling te toets. Die ondersoek het die verwagte woordelige effek
van die gekombineerde PHWE en FCCI voorbehandelings van die houtspaanders op die
papierstrkte-eienskappe bevestig. Bo en behalve dit, het die gekombineerde behandeling ook
die aavanklikte bindsterkte potensiaal van die ongeklopte vessels verbeter.
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Enzymatic pitch control in the kraft pulping and bleaching of Eucalyptus spp.Scheepers, Gerhardus C. (Gerhardus Coenraad) 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The extractive materials in wood often cause pitch problems in pulp mills. During pulping and
bleaching extractives are released from the wood and pulp and later stick to ceramic and metal
parts, forming pitch deposits. Pitch deposits impair both product quality and production rates. It
decreases the efficiency of pulp washing, screening, centrifugal cleaning, and refining, and can
disrupt many paper machine operations. The deposits also break loose from equipment and
cause spots in the final product. There are a few triggering mechanisms that induce pitch
deposition. Hydrodynamic or mechanical shear can destabilise the colloidal pitch emulsion,
causing pitch to agglomerate and deposits to form. Similarly, sudden temperature drops and/or
pH shocks and/or the introduction of water hardness ions from fresh water inlets or showers can
also cause pitch deposits by destabilising the colloidal pitch emulsion. Inorganic salts, such as
calcium carbonate, can catalyse pitch deposition by acting as the building blocks for the sticky
pitch. Calcium ions in the white water can react with fatty acids, forming insoluble, sticky
calcium soaps. Triglycerides have also been shown to be a major contributor to pitch deposition
in kraft pulping and bleaching mills. It forms a sticky deposit to which less sticky particles
attach.
To attain an improved understanding of pitch problems associated with the kraft pulping and
bleaching of Eucalyptus spp., various analyses were done on wood- and pulp extractives and
pitch from a South African kraft pulp mill. High molecular weight compounds (involatile)
constituted a large portion of the extracts and pitch. Approximately 40% of volatile Eucalyptus
grandis extract was f3-sitosterol, with fatty acids (22.8%) and triglycerides (15.5%) also making
a substantial contribution. Fatty acid amides were a prominent fraction of pulp extracts from the
latter stages of bleaching. The amides constituted 38.3% and triglycerides 10.1% to total volatile
pitch deposits.
Lipases hydrolyse triglycerides and could therefore help to reduce pitch problems. Consequently
381 filamentous fungi isolated from indigenous and commercial forests in South Africa were
screened for lipase activity on tributyrin and Tween 80. Eight strains were selected and the
tributyrin and Tween 80 assays were repeated by monitoring lipase activity over a seven-day period. The selected strains were also assayed for their activity toward p-nitrophenyl palmitate.
Ophiostoma piliferum Cartapip 58™ and Phanerochaete chrysosporium BKM-F-1767, two
strains known for respectively their biodepitching and biopulping ability, were' used as controls.
A few of the strains compared well and even outperformed the control strains, indicating their
potential for use in pitch control.
The effect of pretreatment with the eight selected fungal strains on E. grandis wood- and pulp
extractives was determined. Cartapip 58™ and P. chrysosporium BKM-F-1767 were used as
control strains. Several of the strains compared well to the control strains in their ability to
reduce the triglyceride content of wood extract. The South African isolate, white-rot fungus
Phanerochaete psuedomagnoliae nom. prov., reduced triglyceride content significantly.
Consequently it can act as an agent for both biopulping and biodepitching. The treated wood
samples had a lower triglyceride content than the sterile controls. Consequently more
triglycerides would be released into process waters by the sterile controls than the treated
samples. The effect of commerciallipases on deposited brown stock pulp extract was also
evaluated. The lipases did not reduce the triglyceride content of the deposited extract. The
addition of lipases in pulping and bleaching processes would therefore not affect already
deposited pitch. / AFRIKAANSE OPSOMMING: Die ekstrakstowwe van hout veroorsaak dikwels 'n neerslag tydens verpulping. Gedurende
verpulping en bleiking kom ekstrakstowwe van die hout enpulp vry en kleef aan keramiek- en
metaalonderdele. Gevolglik benadeel dié neerslag produkkwaliteit en produksietempo. Dit
verlaag die effektiwiteit van pulpwas, sifting, sentrifugale skoonmaakprosesse en suiwering, en
kan die werkverrigting van papiermasjiene ontwrig. Die neerslag kan ook later los breek en
kolletjies op die finale produk veroorsaak. Verskeie meganismes kan die neerslag veroorsaak.
Hidrodinamiese of meganiese wrywing kan die kolloïdale ekstrakstofemulsie destabiliseer en
sodoende die ekstrakstof laat konglomereer en neerslaan. Op soortgelyke wyse veroorsaak
skielike temperatuurverlaging en/of pH-skokke en/of die toevoeging van ione in varswater om
waterhardheid te beheer ook die neerslag deur die kolloïdale ekstrakstofemulsie te destabiliseer.
Anorganiese sout soos kalsiumkarbonaat kan neerslagvorming kataliseer omdat dit optree as
bousteen vir die klewerige, sementagtige ekstrakstowwe. Kalsiumione in die proseswater kan
ook reageer met vetsure om onoplosbare, klewerige kalsiumsepe te vorm. Dit is bewys dat
trigliseriede een van die hoofoorsake is in die vorming van die neerslag tydens kraft verpulpingen
bleikingprosesse.
Om die neerslagreaksie wat met die kraft verpulping en bleiking van Eucalyptus spp. geassosieer
word, beter te verstaan, is verskeie analises op hout- en pulpekstrakte asook die neerslag van 'n
Suid-Afrikaanse kraft verpulpingsaanleg uitgevoer. Hoë molekulêre massa (nie-vlugtige)
stowwe het 'n groot gedeelte van die ekstrakte en neerslag uitgemaak. Ongeveer 40% van die
vlugtige Eucalyptus grand is ekstrak bestaan uit ~-sitosterol met vet sure (22.8%) en trigliseriede
(15.5%) wat ook aansienlike bydraes lewer. Vetsuuramiede verteenwoordig 'n beduidende
komponent van pulpekstrak by die laaste stadiums van bleiking. Die amiede het 38.3% en
trigliseriede 10.1%tot die vlugtige fraksie van die neerslag bygedra.
Lipases hidroliseer trigliseriede en kan dus help om neerslagprobleme te voorkom. Gevolglik is
381 filamentagtige fungi geïsoleer uit inheemse en kommersiële woude van Suid-Afrika en hul
lipase-aktiwiteit op tributyrin en Tween 80 geëvalueer. Agt rasse is geselekteer en die tributyrin
en Tween 80 toetse is herhaal deur lipase-aktiwiteit oor 'n sewe-dag periode te monitor. Die
geselekteerde rasse is ook getoets vir lipase-aktiwiteit met p-nitrofenielpalmitaat. Ophiostoma piliferum Cartapip 58™ en Phanerochaete chrysosporium BKM-F-1767, twee rasse wat
daarvoor bekend staan vir onderskeidelik hul vermoë om houtekstrakstowwe te verminder en te
bioverpulp, is as kontroles gebruik. 'n Paar van die geselekteerde rasse het goed vergelyk en
selfs beter presteer as die kontrolerasse; 'n aanduiding van hul potensiaal om neerslagreaksies te
beheer.
Die effek van voorafbehandeling met die agt geselekteerde fungi rasse op E. grandis hout- en
pulpekstrak is vasgestel. Cartapip 58™ en P. chrysosporium BKM-F-1767 is gebruik as
kontrolerasse. Verskeie rasse het goed vergelyk met die kontrolerasse in hul vermoë om die
trigliseriedinhoud van die houtekstrak te verlaag. Die Suid-Afrikaanse isolaat,
witverrottingswam Phanerochaete pseudomagnoliae nom. prov., het ook die trigliseried inhoud
beduidend verminder. Gevolglik sou dit as 'n middel kon dien vir beide neerslagvoorkoming en
bioverpulping. Die trigliseriedinhoud van die behandelde monsters was laer as dié van steriele
kontroles. Gevolglik sal meer trigliseriede in proseswater vrygestel word deur die steriele
kontroles as die behandelde monsters. Die effek van kommersiële lipases op ongebleikte kraft
pulpekstrakneerslag is ook geëvalueer. Omdat lipases nie die trigliseriedinhoud van die neerslag
kon verlaag nie sal die gebruik van lipases dus nie die ekstrakstofneerslag in verpulpings- en
bleikingsprosesse beïnvloed nie.
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