I fl 0p 4Q r TechnicalArJcle

Desenvolvimentos da biopolpaaono Brasil

Biopulping developments in Brazil

Autorltrsthor Andre Ferraz

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Palarrasshave Biodegradaaoda madeira biopo

17aaocelulose lignina polpa e paps

RESUMO

A biopolparrao e uma tecnologia cujaaplicaao pods servantajosa para polpaaomecanica ou quim ice Ela apresenta beneficios tais como produczao de polpa mais resistenteeconomia de energia ou de produtos quimicos Este artigoapresenta uma vireo de conjunto dos recentes trabalhosno sentido de desenvolver processor de biopolparzao nohrasil fornecendo tambem informaoes relevantes sobreo desenvolvimento da biopolpaao em escala mundial Foram biotratados cavacos de madeira de Eiecalyptus grandtscom Ceriporiops7s subvernrisporca Hama plantaphoto com

capacidade de 50 t e usados para produzir polpas TMP eCTMP em escala industrial Foram observadas economies

de energia de ate 1R e 27 na produao de polpas TMPe CTMP com grau de refino de 450470 CSF CanadianStandard Freeness Apesar de resultarproduao cle polpasBioThPmais escuras branqueamento de um estagia com5 de H2O foi suficiente para aprimorar os valores de alvura de polpas BioTMP e de controls para 70io e 72 ISOrespectivamente A compreensaodos mecanismos de biopol

paaotambem e relevante porque poderiam ser selecionadasespecies fungicas mais resistentes e competitivas com baseHum projeto orientado para a funao depurarao No que serefers as alterarzoes quimicas na madeira induzidas pelofungo esforros recentes assinalaram doffs diferentes tiposde transformaao da madeira Um envolve intense despolimerizaraade lignina em curtos periodos de biotratamentaenquanto 0 outro indica que rearoes de esterificarao deozalato secretado pelo fungo Has cadeias de polissacarideos

Keyworcls Biopulping cellydrrselisis pazlparrdtcxter tivrrrrd Bicrdegrcxrlaticrn

asrRacr

Biopulping is a technology which application canbe advantageous to mechanical or chenrieal pulping Itpresents Benefits such as the creationofstronger pulp as well as enemy or chemicals srnsingsThis paper gives an overview of the recent effortsto develop Biopulping processes in Brazil as well asprovides criticalinformation on Biopulping development worldwide Earcalyptusgandis wood chipshave been Biatreated by Ceriporiopsis suBvermispora in a SOton Biopulpingpilotplant and used to

produce T121 andCT2pulps on a mill scale LTpto 1 acrd 27 enemy savings hcneBeen obsefed

forprodarcing 45040CSFreeness TMP and CTMPpulps Despite darker BioTIIIPpulps are producedonestage bleaching with 5HOz was sufficient toimprove Brightness values to 0and 72ir for BioT11fP ccnd eontrolpulps respectively tnderstanding

Biopulping mechanisms is also relevant Becausemore resistant and carrspetitive fungal species couldbe selected with Basis on afunctiondirected screen

ing project sfar as the chemical changes induced

By the fungus in wood are concerned recent effortshave pointed orrtfor twodierent types ofwoodtrcrnsforrnations One of them involves intense lignindepolymerizrxtion in short biotreatmentperiodswhile the other indicates drat esterificcrtion eactionsofoxalate secreted By the fungus on the polysaccharides drains increase the water saturation point

Reterencias dos Autores Aathorsreferences

Escola de Engenharia tle Lorene Universitlatle tle Sao Paulo Lorene SP BrasilLarenasfngrneerrng School San Pauln State Unrversrty Lvrena SP Brazrl

Autor correspondents Corespondrrgathor

A Ferraz Escola tle Engenharia tle Lorene Universitlatle tle Sao Paulo CP 116 12602810 Lorene SP Brasil

PhoneFax 55 12 3153 3165E Emailaferrazcdebiqtaenquil

br

elevam o ponto de saturaaode agua das fibras Esperase

que ambas as transformaoesafetem as ligacoesfibrafibrae consegtiientemente a resistencia fisica da madeira

INTRDDUADA biopolparao e opretratamento fungico de cavacos de

madeira projetado comp um processo de fermentaao de estado solido Para a proclurao de polpas mecanica ou quimica O

processo e direcionado a produCao de polpas para fabricaraode papel de menor demanda de energia para o desfibramentorefinarao ou economia cle produtos quim icon bem compme

lhores propriedades de resistencia O conceito de biopolpaaose baseia na capacidade de alguns fungus de decomposiCaoBranca formar colonias e degradar seletivamente a lignina damadeira deixando delta maneira a celulose relativamenteintacta Ha necessidade de certas condiCOes de processo e

exigencias de projeto para se obter o efeito de biopolpaao1 A biopolpacao pode ser realizada em biorreatares dediferentes tipos inclusive pilhas de cavacos a ceu abertoclependendo das necessidades do microrganismo especificopara a obtenrao dos resultados estabelecidos Durante a

etapa do biotratamento deveria ser mantido um elevado teor

de umidade aproximadamente no ponto de saturaraodas

fibras nos cavacos de madeira isso a fim de assegurar otima

form aaode colonias e penetraaode hifas fungicas O graude assepsia deveria sercontrolado para assegurarcolonizaaobemsucedida da madeira pela linhagem fungica especificausada clependendo de sua resistencia a contaminaraoe tam

bem capacidade de competir com a biota m icrobiana existentsnos cavacos de madeira

Outro topico relevante refersse a compreensao dasmecanismos de biopolparaouma vez que poderiam ser se

lecionadasespecies fungicas mail resistentes ecompetitivascom base em projeto direcionado para a funrao depuraraoA degradaaoeoumodificarao seletivas de lignina nativa na

madeira poi fungus de decomposiao Branca pode facilitar asua remoaoou amolecimento no processo de polpaCao sub

segiiente Contudo o grau de remorao de lignina durante opretratamento fungico nao esta relacionado com a economiade energia na polpaCao biomecanica23nem com o aumentodas velocidades de deslignificaaoobservado na polparaoorgunosoly 4 e no processo kraft Dados obtidos de uma

unica especie fungica ou de diversas especies consideradasconjuntamente indicam que nao ha uma correlaaoClara entre

a eficiencia da biopolpaao e as perdas de peso au de componentes damadeira Numa primeiraabordagem podesepustular que modificaroes morfologicas da madeira ou a remoaode alguns compunentes secundarios da madeira tail Comoresinas ou polifenois extrativos poderiam ser responsaveispelos beneficios da biupolpaao Nao obstante modificaaessuperestruturais da madeira que resultam em aumento de

porosidade e remoraode extrativos sao usualmente progres

ofthe fibers Both iransforrriations are expected toaffect thefiberfiber bonding and consequently thephysical resistance ofwood

INTIOflIlCTION

I3iopulping is ilre fungal pretreatment ofwoodchips designed as asolidstate ferrnentatiore process forproduction ofmechanical or chemical pulpThe process is directed towards production ofpulpsforpcxperrnaking with decreased energyrequirernerats for defiberingirefinireg or with chemical savings as well as improved strength properties Theconcept ofbiopulping is based on the abilityojsomewhiterot fungi to colonize and degrade selectivelylignin in wood thereby leaving cellulose relativelyintact There are certcxinprocess conditions and

design requirements necessary to gain a biopulpingeffect IJ Biopulping can be carried out in bioreacfors ofdifferent types including open chip pilesdepending on the requirements ofthe particularmicroorganism would Iecxve for optimal results Highnsoisture content at about the fiber saturation pointshould be kept in wood chips during the biotreat

rrsentstep to ensure an optimal colonization andpenetration of fungal h3rphae The degree ofasepsisshould be controlled to ensure cx successful woodcolonization by the particularfungal strain used depereding on its resistance agcxinst contamination and

ability to corrzpete with the microbial biota availablein the wood chips

Another relevant subject is to understand biopulping mechanisms since more resistant and

competitive fungal species couldbe selected withbasis on ajixnctiondirected screening project Theselective degradation acedor modification ofnative lignin in tivood by tivhiterotjixngi can fcxcilitateits removal or softening in a srrbsecluent pulping

process Hoaever the extent of lignin removalduring fungal pretreatment is not related to tlaeenergy savings in biomeehanical pulping23J orto the increase in delignificatiore rcxfes observedin organasoly 4J arrd kraft pulping 5J Data ob

tainedfrom asingle fungal species orjom severalspecies considered cxltogetleer indicate that thereis reo clear correlation bettiween the biopulping fficiencv and the wood weight or component lossess afirst approach it care be postulated that mor

phological wood modifications or removexl ofsomerrrinorwood comfroreents such as resins orpoly

phenols extractives could be responsible for thebiopulping benefits Nevertheless ultrastructurcxlood rrrodifications thatresult in porosit increase

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sivas em funrao do tempo de biodegradaaoao passo que os

beneficios da biopolpaao nao o sao 5 Resultados recentesassinalam boas correlaoes entre os beneficios da biopolparaoe a intense despolimerizaaoda lignina observada duranteos estagios iniciais do biotratamento da madeira por fungosseletivos de decomposiaobranca 7 esterificaraodeoxalato produzida pelo fungo nas fibres aumenta o panto desaturarao des fibres e esta bem correlacionada a economiesde energia observadas na polparaobiomecanica 3

Este artigo fornece uma visao geral dos recentes desenvolvimentos da biopolparaorealizada numa plantapilotocom capacidade de 50 texistente no Brasil bem coma denovas metodologias de polpaaode amostras de madeirabiotratadas Tambem sao discutidos progresses em relaraoaosmecanismos envolvidos na transformaao decomponentesda madeira pelo fungo de biopolparao o C subvermisporausado na maioria des vezes

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Processamento de TMP e CTMP de Eucalyptusgrandisbiotratado em plantapiloto com capacidade de 50 t

Foram avaliados cavacos de madeira de E grundisbiotratados com C subvermtspora numa pilha de cavacosde 50 tPara processamento de TIvIP e CTMP em escalaindustrial 89 Para um dos ensaios o consumo de energia

pare produzir polpas com 450470 CSF sob condioes de

processamento de TMP e CTMP foi reduzido em 1 e

27respectivamentehs polpas bioTMP produzidas industrialmente eram

mais escuras que a TMP de controle 9 enquanto a CTMP

apresentava valores de alvura semelhantes em ambos os

casos 8 Na TIv1P foi observada reduao de ate 16 pontosde alvura para as polpas preparadas nas pesquisas daplanta

piloto 9 Todavia foi interessante notar que quando a bioTMP de E grandis foi submetida a branqueamento comperoxido a rearao de controle em que biopolpa tratada com

acido pentaceticodetriaminadietilenica foi embebida emalcali pH 11 e em seguida lavada em ague proporcionouaumento daalvura inicial dabioT1VIF de 44pare 55ISO

Inversamente o mesmo tratamento teve efeito de branqueamento insignificante na TIvIP de controle Figure 1 Este

resultado indica que uma frarrao dos cromoforos presenteeem biopolpas e facilmente removivel por meio de um sim

ples tratamento alcalino Com identicas cargas de peroxidoa bioTMPobteve mais pontos de branqueamento do que as

polpas de controle Noentanto a alvura finaldes biopolpas era

sempre ligeiramente inferior a alvura des polpas de controleindepenclentemente dacarga deperoxido aplicada Para o caso

de branqueamento de um estagio com 5 de peroxido dehidrogenio os valores de ahura eram de 70 e de72paraa bioTMPe as polpas decontrole respectivamente Dosagensmais altas de peroxido tiveram um efeito naasignificativa naalvura final de ambas as polpas Figure 1

and extractives removal are usually Progressivewith biodegradation time whereas the biopulpingbenefits are not f5 Recent resarlts point out forgood correlations between biopulping benefits andintense lignin depolyrneriation observed duringthe initial stages oftivood biotreaimentby selectivewhiterot fungi J Esterification of oxalate produced by thefrrgars to the fibers improves the fibersaturation point and correlates well with energy

savings observed in biomechanieal pulping f3JThis rapernovides an overiew oftle recent

advances of biopulping perrforrned on a 0tonpilotplant established in Brazil as well as on near

rrrethodologies for pulping biotreated ood samples1dvarceson the mechanisms involved in wood com

ponent transformation by the mostly usedbioulpirgfungus C subvermispor is also discussed

TtIPaxd CT1LIP processing ofEucalyptus grrrnksbiotreated orr aSOtonpilotplant

E grardiswood chips bioirecrtedhv C subver

mispora in a l1ton chip pde have been evaluatedforT2P andCT2Pprocessing on a mill scale

8 9 For one of the trials energy consumption under TlIPand CTwIP processing conditions were re

duced by 1 c43o and27 respectively forproducingpulps with 45047DCSF

Industrially producedbioT1IIPpulps were darker than controlT121f9 wl2ile CT1V1F presentedsimilar brightness values in both cases 8J In711Pa reduction ofup to 16 brightness points hers beenobservedfor the pulps prepared on the pilotplantstudies j9 However it was interesting to note that

when bioTMPfrom E grandis was submitted to

peroxide bleaching the control reaction in whichDTPAtreatedbiopulp was soaxedin alkali pH 11and then washed in water provided an increase in

initialbioT1IPbrightness front 4to SISOConversely the same treatment hada negligiblebleaching effect on the control711P FigurelThisresult indicates that a fraction of theclromophorespresent in biopulps are easilyremrnable by a simplealkaline treatmentl4tidentical peroxide loads bioT111P gained rnorebleaching points t1ant1econtrolpulps However the final brightness ofthe biopulpswas always slightly lotiver than the brightness of thecontrolpulps regardless of the peroxide charge applied For onestage bleaching with Sc hydrogenperoxide brightness values were 70 and12forbioT2Pand control pulps respectively Higherperoxide dosages had negligible efect on the finalbrightness ofboth pulps Figure I

Testes de fotorreversao

e de reversao termica realizados em TMP e bioTMP

branqueadas mostraram quea bioTMP era mais estavel

durante as primeiras horasde fotoamarelecimento em

compararaocom a TMP de

cantrole 9 Por exemplobioTIvLP branqueada com alvura initialde6io perdeu 18

pontos de alvura ap6s 1 horade fotorreversao enquantoa TIviP de controle com a

mesma alvura initial perdeu24 pontos durante o mesmo

periodo Contudo uma fotorreversao prolongada resultouem valores de alvura seme

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a 70a

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polpa naotratada

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0 2 4 6 8 10 12 14

Carga de pernxida de hidrogeniopesolpeso base polpa

Figura 1 Respostas do branqueamento de polpas ter

momecanicas preparadas a partir de cavacns de madeira

de E grandis naoiratadoscirculos vazios a biotraiadoscom G subvermispnra circulos pretos

lhantes Para ambas as polpas Figure iEieaching responses oftirerrromechanical pulps

Photo and thermal

reversion testsperforrnedon bleached T1lIPand

bioT1IPshowed that

bioT1lIP were more

stable during tlsersthours ofphoto yelloNing when compared tocontrolT1P9J For

example bleached bioPtiiiih 63 initial

brightness lost IS brightness points after 1 hourofphotoreversion whilecontrol711Pwith tlae

carne iraitial brightnesslost24 points during thesame period Howeer

polongedphotoneversiora resulted in similar

A bioTMP perdeu menos prepared from untreatedvpencirciesandGsubvermispn briglatnessvalues jotpontos de alvura clo clue a rahiotreated E grandis wood chips blackfilled circles both ul as BioTl2P lostT1vIP de controle do inicioao fim dos testes de reversao termica Diagram as da reversao

da alvura em funcao da alvura initial permitem uma amplavisao da estabilidade da alvura das polpas estudadas Com

base nesses graficos Figura 2 fica claro que a estabilidadedaahura da TIviP de controle e dabioTIvIP branqueadas em

relaao a fotorreversao era semelhante enquanto abioTMPera ligeiramente mais estavel em relacao a reversao termicado que a T1viP de controle

060

AO 55rn

Q50

aQry 45

i 40ro

a d 35

a 3040 50 60 70 80

Alvura initial ISD

p

less brightness pointsthan controlT1IPthroughout the thermal reversiontestsPlots ofbrightness reversion as afunction ofinitial brightness permit a broad view of the brightness stability of the stradiedpulps Based on these

plots Figure 2 it is clear that the brightness stab ilitt ofbleached control andbioTMP to photoreversionwere similar while bioTRIPwas slightly morestable totheyrnalreversion than controlT1IP

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vro 10m

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da

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30 50 70 80

Alvura inieialIISO

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Figura 2 Fotorreversao A a reversao termica B da alvura em iungao de niveis de alvura initial em polpas TMP bran wqueadas com pernxida preparadas a partir de cavacns de madeira de E grandisnaatratados circulosabertos a biotratadoscom G subvermispnra circulos pretosFigure 2 Phatn Aand thermalreversion8 ofbrightness as a functian vt initialbrightnesslevels inperoxidebleached TliiPpulps prepared from untreatet open circles and C subvermispnrahiotreated E grandis wood chips black filled circles

Polpas bioCTMPde E grandis

Polpas bioCTIl produzidas industrialmente ate estadata nao foram avaliadas com detalhes mas foram estudadas

polpas preparadas em laboratoria a partir deE grcandis biotratadas num biorreator de 100 L por 15 dins Amostras

biotratadas e controles naoinoculados foram precozidosem sulfito alcalino e posrefinados em moinho Jokro Estesimples procedimento demonstrou ser eficiente para aproduao de polpas CTNIP com propriedades de resistenciasemelhantes as observadas em polpas CTIdP produzidasindustrialm ente a partir de E grandis O rendimento total da

polpa a quantidade de polpa rejeitada e os niveis do grau derefino da polpa sao apresentados na Tabela 1 O rendimentototal da polpa variou de 7ioa 76 em funrao do tempo derefino As biopolpas apresentaram m enor rendim ento total do

que as polpas de controle para periodos de refino semelhan

tes Par outro lido as biopolpas fibrilavam mais rapidamentee continham menores quantidades de rejeitos Comparandose os rendimentos da polpa com base em niveis de refinosemelhantes verificaseque os rendimentos da polpa cramsemelhantes em ambos os casos Uma rapida fibrilagao das

biopolpas poderia representar aumento na produtividade doprocessa ou economia de energia durante a etapa de refinoja que seria necessariomenor tempo de refinaao para atingiro grau de drenagem desejado Por exemplo para atingir um

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BioCT1IPPtclps frora E gratidisIndustiallproducedbioCTMP pulps ere

not evalatatelin details to date bast lab rreparedpulps from Egrandis biotreated in a 100Lbioreactor for 1 S days were studied j8J Biotreatedsamples andnoninoculated controls were precooked in alkaline sulfite andpostrefined in aJokro mill This sirnple procedtrre showed to beefficient to produce CTMP pulps with strengthproperties similar to that observed in industrially

producedCTIIPpaalps from E grandis Totalpulpyield amount of rejected pulp and freeness pulplevels are presented in Table 1 Total pulp yieldvaried frorrs 8to7iuoas a function ofthe beating time The biopulps presented lower total pulpyield than the control pulps at similar refiningperiods On the other hand the biopulpsfibrillated more rapidl3 and contairsed lower amoaents

ofrejects Then pulp yields are cornpared atsimilar refining letiels pulp yields were similar inboth cases Rapidfibrillation of the biopulps couldrepresent increases in the process throughput orenergy savings during the refining step since areduced heating tiarae is necessary to achieve a desiredfreeness letiel For exarrrple to achieve 400

Tabela 1 Rendimento de polpaao quantidade de rejeitos a grau de fibrilaaode polpas CTMP preparadas a partir decavacos de madeira de Eucatyptusgrandis naotratadas a biofratadosTabie 1Prrpirtg yield amount et rejects and degree at fibrillation of TNiP pulps prepared tram untreated and biotreated

Eucalyptus grandis wand chips

E grandis naotratado F grandis biotratado

ttreated ranris iataaad rrandis

Tempo de refino min Rendimento total Rejeitos CSF Rendimento total Rejeiios CSFeeatin time min ap mL lo lo mL

Total ieict Rejects CSF Total grield Rejects CSF

a ro nr1 rQlo rm

30 868 336 708 849 304 702

3t 3ig 636 i0S r34cJ t4 D

60 843 100 638 832 74 622

60 8a3 f66 63v i2 r 4 6

90 834 28 604 795 12 4 24

JlfJUJti U tlLY 7 7J Ff

120 808 0 432 776 0 323

12J r3 0 432 776 0 623

135 783 0 323 760 0 253

1Ji Usj V vG 6Q V J

grau cle drenagem de 400 mL a polpa de controle requeria125 min de refina5o enquanto a biopolpa requeria somente95 min tempo de refino reduzida em 24

4s propriedades de resistencia de polpas preparadas a partirde amostras biotratadas durante 15 dins estao representadasna Figura 3 Os indices cle resistencia a trarao da biopolpaaumentaram significativamente243e62com grausde refinaCao de 630 mL e 430 mL respectivamente enquantoa resistencia ao rasgo melhorou somente para polpas com grausde refinaao inferiores a 500 mL 25 com grau de refinode 320 mL Os indices de estouro eram semelhantes paraambas as polpas Graficos detraaoversus rasgo Figura 3Dindicaram claramente que as biopolpas apresentaammelhores

propriedades de resistencia do que as polpas de controle ja queforam obtidos indices de traaomais altos em toda a faixa deindices de rasgo Scott et ul 10 aualiando um processo deTMP de doffs estagios em escala laboratorial para E grandisbiotratado obsenaram que a economic de energia para pro

duzirpolpas com um grau de refino de 400 mL era de 17ro eque polpas bioTIvIP comparadas com as polpas de controle

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z 50o

ck40

a 30a

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ZO

700 500 300 100

Grau de refinacao mL

3

Y za

a

1

0

700 500 300 100

Grau de refinaaomL

rraL offieeness the control pulpreeuired 125 minofbeating while the bioplpp required only 95 minbeating time redarced b 24ivStreragth properties ofpulps preparedfrom

1Sdel hiotreated samples are shown in Figure3 Biopulp tensile indexes increased significantly243 and 62at 630 mL and 430 mL offieenessrespectivellJ while tear strength unproved onlvfor pulps ith freeness values below500 mL 25io at 320 mL offieeness Burst indexes were similcrr for botl2 pulps Tensile versustear graphs Figure 3D clearly indicated that the

biopulps presented bette strengthpoperties thanthe control pulps since higher tensile indexesere obtainedfor tlae entire range oftear indexesScott et al f10 evaluating alabscale twostageTllIP process for biotreated E grandis observedthat energy saving for producing pulps with 400rnL offreeness wits1 and bioT111Ppulpspresented doubled tensile and tear indexes hen

6

z 5toy

ma

3u a

c

2

700 500 300 100

Grau de refinaraomL

60

as

z 50

aMtry Sr

m 40z

as1i 30swc

20

3 4 5 fi

Indite de rasgo mNmIg

Figura 3Propriedades de resistencia de polpas CTMP preparadas em escala laboratorial a partir de cavacos de madeirade Eucalyptus grandisnaairatados simbolos abertos a biofratados simbolos pretosFigure 3 trengtlr lrrolaerties atCT1lr1P pulps prepared an labscaletrcna rtntreated open sytnbnls andbiotreated black tilledsymbols Fuealylltrrs grandis wend chips

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exibiam indices de trarrao e de rasgo dugs vezes mais altos Essa

maior resistencia das biopolpas vem perm itir a preparaaedem isturas de polpas para produrao de papel tissue usandose80 debioTMP e somente 20 de polpa kraftbranqueadaao inves da tipica proporraode 5050usada com polpasTMP convencionais No taro de polpas CTMP de E grandisos uumentos nas propriedades de resistencia nao foram taesignificativos quanto os observados na TIvIP Para finsde com

pararao polpas bioCTMPcom um grau de refinaCao de 400

mL apresentaram indices de tracao e de rasgo com melhoria

de6 e 13 respectivamente Figure 3

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Mecanismos de biopotpagaoEmbora a tecnologia de biopolparao tenha lido avaliada

em estate industrial 1910 seus fundamentos quimicose bioquimicos ainda nao foram totalmente compreenclidesEm gerul os efeitosbenefices dopretrutamente damadeiracom fungus de decomposirrao Branca sae obtidos nos estagiosiniciais da biodegradurao sendo as perdas de peso inferiores a 5lDurante periodos de biodegradaaobreves deuma semana de durarao cavacos de madeira biotratadostornamse mais metier e mais faceis de serem rompidosao longo das eixos das fibras Este efeito de amolecimentotem censtituido a base para umaproposicaoinitial de pretratamento biologico de caacos de madeira para polparaomecanica 1 Nu polpacao mecanica cavacos de madeirasae desagregados em refinadores de discos para produzirfibras setter e bemfibriladas adequadas para a fabricacaode

papel Oprocesso envolve demanda intensive de energia e aqualidade da polpa depende de diversas variaveis inclusivedaconfiguraao dos refinadores du especie du madeira e donivel de refine desejado Deste mode cavacosde madeira quese separam aoLongo das fibras mediante aplicarao de menor

forrumecanica pouparium energia e proporcionariam polpasmais resistentes simplesmente porque as fibras sofreriam

mends dunes durante as etapas de refineA despeito de um ampleprocesso de pesquisa ao Longo

da ultima decade muitas questoes continuum pendentesPor que cavacos de madeira biotratados facilitam os

processor de polpaaoQuaffs sae as alteraoesquimicasinduzidas pele fungo na madeira que proporcionam oefeito de amolecimento supracitado Quaffs sae os agentesbioquimicos envolvidos Ha um fator isolado que e responsavel peter beneficios da biopolparao No que concerneus ulteraroes quimicas induzidas pelo fungo nu madeiraestudos recentes tem assinalado doffs diferentes tipos de

transformarao da madeira Um envolve intense despolime

rizaao da lignina em periodos de biotratamento de curtadurarrao 6711 enquanto 0 outro indite que reacroes deesterificaao de oxalate secretado pelo fungo nas cadeiasde polissacarideos aumentam o ponto de saturacaode aguedes fibras 3 Esperaseque embus as transformaoesafe

compared to control pulps This irnproved strengthofhiopulps allosthe preparation ofpulp blends

for tisszepaper production using b0obioTMPar2d only 20bleached1aftpulp instead the

typical505Q usediith conventional TllPpulps In the case of CTMP gulps ofE grandisincreases in the strength properties tivere not assignificant as observedfor T111P For comparisonpurposes bioCTil1P pulps with 400 mL offieeraess presented tensile and tear indexes improvedby 6and1respectively Figure i

Meclaaraisms are biopulpiraaAlthough biopulping technology has been

evaluated on mill scale jl9 IOJ its chemicaland biochemical bases ase not completely understood In general the beneficial effects ofwoodpretreatment with whiterotfingi are obtained ofthe early stages ofbiodegradation weight lossesbeing lower than 5lJ YVithin biodegradationperiods as slaort as one week biotrecrted wood

chips become softer and easier to disrupt alongthe fiber axes This softering effect has been thebasis for initialproposal of biological pretreatment ofwood chips for mechanical pulping IJ Inmechanical pulping wood chips are disrupted indisk refiners to producefree and well fibrillatedfibers sreitable for papermaking The process isenergy intensive andpulp qualify depends on several vuriables including tlae refiners design wood

species and the desired refiring level In thiscxv wood chips that disrupt along fibers by re

quiring Zess mechanical strain would saeenergyandprovide stronger pulps simply because fiberswould suffer less darn age during refining steps

Despite extensive investigation over the lastdecade many questions still remain Yhy biotreat

ediood chips facilitate pulpingprocesses bfhatare flee cherniccrl changes induced bflee fungusin wood that provide t1eaforementioned softeningoffect Yhat are the biochemical agents involvedIs there a single factor responsible for tle bioparlping benfits14sfcras the ehemicccl changesinduced by the fungus in wood are concernedrecent tforts have pointed outfor ttiro differenttypes of woodtransforn2ations One of them involves intense lignin depolvmerization in short

biofreatmentperiods 6 IIJ while the otherindicates t1at esterification reactions ofoxalatesecreted by the fungus on the polysaccharideschains increase the wafer safuration point of thefibers 3 Botl2 transforrrrations are expected to

tem a ligacaofibsfibse consequentemente a resistenciafisica da madeira Obviamente essas alteraoes da estrutura damadeira nao sao eventos isaladas e a modificaaoglabal na estrutura e superestrutura damadeira afetariao comportamento de cavacos de madeira biadegradadasdurante os pracessos de polparao mecanica ou quimica

Um fato que requer atenraaadicional e a falta de car

relarao entre os beneficios da biopolpacaoe a grandeza da

perda de peso oude componentes damadeira Por exemploo grau de remoaode lignina durante opretratamentofungico nao esta relacionado com a ecanamia de energiano processa de palpaao biomecanica 23 nem com oaumento des velocidades de deslignificaraoobservadas na

polpaao organosoly 4 e polparao kraft 5 Dados obtidosa partir de uma unite especie de fungo ou de diversasespecies consideradas conjuntamente indicam que nao haumacarrelaao clam entre a eficiencia da biopalpaao e asperdas de peso ou de componentes damadeira 2

Uma ample remocaode extrativos durante a biodegradaaodamadeira par alguns fungos de decamposiaobranca deveria proporcianar alguma redurao no alcalinecessario Para a cozimento par processo kraft E bem

canhecido o fato de que extrativos da madeira resinase grupos acetila sao responsatieis por consumo de alcalina fare initial da polparao kraft 12 A remogao de extrativos pade resultar em canais de resina desobstruidosfacilitando a penetraraodo licor e reduzindo o cansumade alcali ativo por componentes naoligninas Com efeitoeste beneficio tem sido referido como justificative pare o

condicionamento envelhecimento de cavacos de madeirabem comoPara a biatratamento de cavacos pelo fungo naodegradador de lignina Ophtostorrzu piltferum1314

Experimentos de polpacao com cavacos de madeiralivres de extrativos tem sido uteis pare avaliar melhor os

beneficios da remoCao de extrativos durante a biapolpa

cao Os teores de lignina residual em polpas preparadas apartir de amostras sem extrativos sao intermediarios entreos controles indecompostos e amostras biotratadas por Csubverrnisporu5 o que significa que a remaaode extrativos facilita a polpaaopelo processo kraft subsegiienteTodavia isto nao cansegue explicar todos as beneficiosobservados na polpaCaa par processo biokraft umavez

que ate mesmo uma amostra sem extrativos preparadamediante extraraa em etanol nao e deslignificada taofacilmente quanta as amostras biotratadas O grau de

remoraa de extrativos durante a biopolpaCao corroboraesta conclusao ja que de forma semelhante as perdas de

lignina perdas de extrativos sao progressives em funaoda tempo de biodegradarao ao passo que os beneficiosda biatratamento nao a sao 5

Ids alteraroes induzidas em cavacos de madeira queproporcionam beneficios pare processor de polparao

affect thefiberfiber bonding and consequentlythe physicalresistance ofwood Obviousl thesechanges in wood strarctarre are not isolated eventsand the overall change in the wood structure and

ultrastructure tiuorrld offect the behavior of biodegradedwood chips during mechanical or cheryaicalpulping processes

One fact requiring additional attention is thelack of correlation between the biopulping ben

efits and the extent ofwood weight or componentlosses For example the extent of lignin removalduringfungalpretreatment is not related to theenerg savings in biomechanicalpulping Z3J orto the increase in delignification rates observedin organosoly 4J andkraft pulping fSJ Dataobtainedfrom cr single fungal species orfrom several species considered altogether indicate thatthere is rso clear correlcrtionbeeen the biopulping efficiency and the wood weigl2t or corrrponentlosses jZJJ

Extensive removal ofextractives durirg tivood

biodegradation by some whiterot fungi shouldprovide some reduction in the alkali neededforthe craft cooking It is well known that wood extractives resins and acet3lgroups are responsiblefor alkali consumption in the initial phase ofkraftpulping 12J Extractives removal can result inunobstructed resin canals facilitating the Ziquorpenetration and reducing the active alkali consurrrptiora bnonlignin components Actually t1is

benefit has been reportedfor seasoning ofwood

chips as well as for wood cl2ips biotreatment bythe nonlignin degrader fungus Ophiostoma piliferum f1314

Pulping experiments with extractivefreewood chips have been usefirlto better evaluatethe benefits ofextractives removal during bioparlping Tlie residual lignin contents in pulps prepared from extractivefiee samples are intermediate betYVeen the undecuved controls and samplesbiotreated by C suhverrnispora fSJ which meansthat extractives removal facilitates the subse

quent kraft pulping Hotiiever it cannot explainall the benefits observed in biokraftpaslpingsince even a sample without extractives preparedby ethanol extraction is not deligrified as easilyas the hiotreated samples The extent ofextractives removal during biopulping corroboratesthis conclusion since sirrrilcrrly to lignir2 lossesextractive losses are progressive tivith biodegradation time whereas the benefits of the biotreatment are not

0aN

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O

mecanicos nao sao necessariamente as mesmas requeridas pare a polpaaoquimica E relevante observer queembora esteja correlacionada aos beneficios envolvidos na

polpaCao biomecanica 3 nao se espera que a esterificaraode oxalato nas fibras apresente um claro beneficio pare y

polparaopor processo kraft porque os esteres de oxalatoconsumiriam parcela do alcali ativo usado no processode cozimento

Numa outra area de atividade fai recentemente referidoo fato de que algumas faixas de radiyao no infravermelhoproximo NIRj da madeira se alteram significativamenteem periodos de biodegradaao de tarty extensao tailComode 4 dies 15 Essay alteraCOes day intensidades de faixas

NIRprovam que modificaaes estruturais em componentes da madeira tem inicio em estagio muito incipiente doprocesso de biodegradacaoMais relevante e o fato de quefaixas NIR podem refietir nao somente alteraoes nas ligaoescovalentes de companentes damadeira may tambem

modificaoes na ligarao entre as fibras tais como pontesde hidrogenio E possivel que alteraroessecundarias em

ligaoes de hidrogenio entre superficies de fibras sejam

responsaveis pelo efeito de amolecimento observadoem cavacos de madeira biatratados por fungos de decomposiaaBranca que facility orompimento damatrizlignocelulosicapor meio de refinadores de discos

Today estas observacoes experimentais enfatizam ofato de que as transformaroes que ocarrem na madeiradurante a biodegradaCao precisam ser investigadas em

detalhe se quisermos chegar y uma descrirao abrangenteda quimica da biopalpacao

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aw

C

Observagoes finais

A avaliarao industrial de cavacos de madeira biotratados tom C subvermrspora name plentyphoto de 50t de capacidade demonstrou que economies de energia

equivalentes podem ser obtidas ny biopolpacao em escylalaboratorial e industrial No que se refere as alteragoes

quimicas induzidas pelo fungo na madeira esforros recentes assinalam doffs cliferentes tipos de transformaaoda madeira Um deles envolve intense despolimerizaaoda ligniny em periodos debiotratamento de tartydurycaoenquanto 0 outro indite que rearoes de esterificaCao deoxalato secretado pelo fungo nay cadeias de polissacarideos aumentam o ponto de saturaraocle ague des fibrasPresumeseque ambas as transfonnaoesafetem a ligaaoentre as fibras e consequentemente a resistencia fisica

da madeira

AGRAUECIMENTOS

Expressamseagraclecimentos pelo suporte financeirocancedido porEPESP CNPq CAPES e Melhoramentos

Papeis Ltda

The changes induced in wood chips drat provide benefits for mechanical pulping processesare not necessarily the same onesrecrriredforchemical pulping It is relevant to note that al

thouglr correlating with the benefits in hiomechcrnical pulping 3 esterificatior2 ofoxalate tothe fibers is not expected to present a clear benefit for kraft pulping because the oxalate estersould consume part of the active allali used inthe cooking process

In anotlrerfiont it lras been recenily reportedthat Borne near infrared 11rIR bands from woodchange significantly in hiodegrudation periodsas short as 4 days fl JJ These changes in RIRhand intensities prove that structured changes inwood components initiate very early daring bio

degradationlore relevant is that NIR bands canreflect not only changes in the covalent bonds ofood components but also changes in fiberfiberbonding such as hydrogen bridges It is possiblethat minor changes in hydrogen bonding betweenfiber surfaces would be responsible by the softening effect observed in wood chips biotreated byhiterot fungi that facilitates disruption of thelignocellulosic matrix by disk refiners

All these experimentcd observations emphasize that the wood transforrnatiorrs occurring dur

ing biodegradation need to be explored in details

ifwe are to arrive at a comprehensive descriptionof the biopulpirrg ehemistr

Finnl rernnrks

Rill evaluation ofwood chips biotreated byC srcbvermispora on a50tonpilotplant demonstrated drat equivalent energy savings can beobtained in lab acrd millscale biopulping As faras the chemical changes induced by the fungus inYIOOd are COrrCernedYeCerrtefOrts lralepOrntEdoutfor twodiererrt types ofwood transformations Qne of them involves intense lignin depolymerization in shortbiotreatmerrtperiods tivhilethe other indicates that esterification reactions ofoxalate secreted by the fungus on the polysaccharides chains increase the water saturation pointof the fibers Both transformations are expected toaffect the fiberfiber bonding and corrsecrrentlytheplrsical resistunce of wood

ACKNOWLfDGEMfNTS

Financial support form FAPESP C11PqCAPES and1elhorcrnrentos Papeis Ltda is ac

krr ovuledge d

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2 Leatham GF 1Vlyers GCyegner TH 1990 Bivrnechanical pulping ofaspen chips Energy savings resultingfrom differentfungal treatments Tappi J 73 5 197200

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