Showing papers in "Appita Journal in 1996"

Chemical analysis of polysaccharides in plantation eucalypt woods and pulps

Abstract: The polysaccharides in a series of Eucalyptus globulus and E. nitens woods, and E. globulus pulps, were analysed by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), following hydrolysis with sulfuric acid. The technique was evaluated as a small-scale method for characterising mltiple samples of eucalyp woods. Acetyl groups and 4-0-methylgluronic acids (MeGUAs) associated with the hemicellulose, fraction were removed during acid hydrolysis and were determined separately. Acetyl and MeGUA results were combined with the hydrolysis results to enable calculation of cellulose and hemicelluloses contents for each sample. The cellulose content of the wood samples varied over the range 41-50% (E. globulus) and 36-44% (E. nitens), although the range of total polysaccharide contents was similar for both woods. Analysis of the pulp polysaccharides after enzymic hydrolysis showed that the pulps contained hexenuronic acids. The analyses for cellulose and hemicellulose content showed satisfactory precision, and gave values similar to those associated with gravimetric determination of cellulose and hemicelluloses. The hydrolysis-HPAECPAD method for carbohydrates is proposed as a better alternative to gravimetric techniques for exploring the relationship between the chemical composition of plantation eucalypt woods and their pulp yields and papermaking properties.

NIR spectroscopy of woods from Eucalyptus globulus

Abstract: The origins of bands in the near-infrared (NIR) spectra of woods from Eucalyptus globulus have been investigated by using a number of approaches. The bands in the spectra have been compared with those in the spectra of eucalypt cellulose, glucuronoxylan, milled wood lignin and hot water extractives, and with bands removed from the wood spectra by treatment of the woods with sodium chlorite and with weak alkali. Furthermore, correlations have been obtained between the absorbances of bands in the NIR spectra and a) the hot water extractives and lignin contents of the woods and b) the absorbances of bands in the mid-infrared (MIR) spectra of the same woods. Many partial correlations were found showing a high degree of intercorrelation between the bands and confirming that the NIR bands arose from combinations of several fundamental bands.

Analytical characteristics of plantation eucalypt woods relating to kraft pulp yields

Abstract: Correlations of the chemical composition of a series of 11 Eucalyptus globulus wood samples ranging in ages from 6 to 32 years, and 21 seven year old E.nitens wood samples have been made with the yields and the composition of their kraft pulps. Analyses for extractives, lignin, pentosan, acetyl, glucuronic acid, and carbohydrates were carried out. The carbohydrates were determined as pentosans, and as their constituent sugar monomers after acid hydrolysis of the unextracted woodmeals and analysis of the hydrolysates by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The total carbohydrates (calculated by difference) and extractives contents of E.globulus wood samples were well correlated with pulp yield at Kappa no.15, and lignin was moderately well correlated total carbohydrates for both species (measured by HPAEC-PAD) were only moderately well correlated with pulp yield. For both species, the correlation of pulp yield with cellulose and glucose was good, but was slightly inferior with hemicellulose, xylose, and pentosan. Wood samples which gave high pulp yields had cellulose as a high proportion of their polysaccharide fraction, and this trend was also evident in the pulps derived from them. Both wood samples showed variation in their oxidation products ; for the E.globulus woods the syringaldehyde/vanillin ratios were moderately well correlated with pulp yield, but for the E.nitens woods, the correlation was poor. The hydrolysis-HPAEC-PAD method for carbohydrates is proposed as a suitable basis to explore the relationship between the chemical composition of plantation eucalypt woods and their pulp yields and papermaking properties.

Eucalypt wood classification by NIR spectroscopy and principal components analysis

Abstract: A number of aspects of pulpwood quality are determined by the chemistry of woods. Bands in the near infrared (NIR) spectra of woods arise from the vibrations of bonds in the chemical components of the woods and can be used as sensitive monitors of changes in their chemistry. Principal components analysis (PCA) can compress most of the variation measured at the 700 points in the NIR spectrum into a few components enabling patterns of relationships to be discerned which might otherwise be overlooked. This paper shows how PCA analyses of the NIR spectra of wood meals can be used to discriminate between woods from pines and eucalypts, between woods from different eucalypt species and amongst provenances, and between woods from the same species of eucalypt on different sites. The chemical significance of the classifications is also discussed.

Microfibril angle scanning of increment cores by x-ray diffractometry

Abstract: The mechanical properties of paper are strongly influenced by the strength and stiffness of the fibres from which it is formed. Fibre strength and stiffness are largely controlled by microfibril angle (MFA). X-ray diffraction patterns have been obtained at sub-millimetre resolution along radial strips from both Pinus radiata and Eucalyptus nitens samples. Variation in MFA, as estimated from the patterns after correction for fibre tilt, has now been added to a range of fibre properties which include coarseness, wall thickness and diameter. A new apparatus includes an X-ray area detector which reduces the measurement time for a single MFA estimate from 60 minutes to 30 seconds. An important criterion for the design of the instrumentation was that measurement must be done using the same samples currently prepared for automated densitometry and image analysis. Therefore no additional sample preparation is necessary. Although the MFA measurement rate-spatial resolution combination cannot match that for the other properties owing to the relative weakness of diffracted radiation, automation and the judicious choice of within-sample measurement positions makes feasible the routine assessment of MFA in increment cores.

Polymer optimization in paper mills by means of a particle size analyser : an alternative to zeta potential measurements

Abstract: A method for the qualitative and quantitative optimization of the use of polymers in paper mills has been developed. Traditionally optimization of the dosage of polymers in the paper and board industry is achieved by using techniques based on the electric charge of the particles. However, the flocculation phenomenon is based on an increase in the size of the particle aggregates, thus the new method is based on size measurements of the particle aggregates. By applying this technique it is possible to determine the effect of the different chemicals under papermaking conditions ; get a better understanding of the interactions occurring in the pulp system ; predict the influence of changes in the raw materials or papermaking conditions on chemical efficiency : and control and optimize the chemical flocculation processes.

The influence of basic density and pulp-yield on the cost of eucalypt kraft pulping: a theoretical model for tree breeding

Abstract: The impacts of genetic improvement of density and pulp yield on the cost of converting roundwood to unbleached kraft pulp are modelled for a greenfield mill. Operating and capital costs are described as functions of density and pulp yield for each stage of the pulp mill including the chemical recovery process. The cost of converting green roundwood to unbleached pulp, per oven dry tonne of unbleached pulp produced, will decrease with increasing density and pulp yield. Pulp yield has the greatest effect on pulping cost, but the degree of influence depends upon the value of energy produced by the recovery boiler : a high energy value reduces the influence of pulp yield on pulping cost. Density has a major influence on the cost of digestion and a minor influence on the cost of evaporation, so a high relative digestion cost increases the influence of density on pulping cost. This paper does not, however, conclude pulp yield to be a more important trait than density for breeding for kraft pulp.

Environmental effects on growth and kraft pulp yield of Eucalyptus globulus and E. nitens.

Abstract: The volume growth and kraft pulp yield (m/m) of two provenances of eight-year-old stands of E. globulus and E. nitens were investigated at four plantations. The plantations were located at 60, 240, 440 and 650 m along an altitudinal gradient in the Esperance valley south-eastern Tasmania. A significant decrease in kraft pulp yield between the lower and upper sites was observed for both species though differences within provenances between sites did not exceed 3.4%. There were significant differences in pulp yield between provenances within species: across sites these yields were 55.7 and 51.6% for the better provenances of E. globulus and E. nitens. The better provenance of E. nitens was superior to E. globulus in terms of volume growth except at the 240 m site which had the highest minimum temperatures. Given careful matching of provenance to site, planting of E. nitens is recommended for maximizing pulpwood production except on frost,free sites at low altitude when the higher pulp yield and similar volume production of E. globulus favours this species.

Enzymatic modification of radiata pine kraft fibre and handsheet properties

Abstract: The response of unbleached and bleached radiata pine slabwood and thinnings kraft fibres to treatment with different purified enzymes are quantified and assessed. The enzymes were two xylanases, a cellobiohydrolase, and three endoglucanases. Unbleached slabwood fibres of high coarseness with thick walls show the greatest response to enzyme treatment. Corresponding fibre and handsheet property differences are smaller for bleached than for unbleached slabwood pulp. Thus, the additional carbohydrate material and/or residual lignin present in the robust fibres of unbleached slabwood pulp must interact in some way during or after enzyme treatment. Some enzyme treatment effects on the unbleached slabwood pulp are : 1) Xylanase treated fibres retain their intrinsic strength but can be stiffer with surfaces of lower water affinity and bonding potential compared to untreated fibres. Handsheet properties are modified with tear index being selectively increased. 2) Cellobiohydrolase treated fibres increase in size and stiffness but retain their intrinsic strength and bonding potential compared to untreated fibres. Handsheet properties are modified but tear index is not selectively increased. 3) Endoglucanase treated fibres (100 μg/g) are degraded with fibre and handsheet strengths lowered. Extents of degradation are different for the three endoglucanases.

Use of the radially divided increment core method to assess pulpwood quality for eucalypt breeding in E. camaldulensis and E. globulus

Abstract: Whole-tree pulp properties were predicted by regression equations using weighted averages of wood properties at given heights below 3.3 m above ground. The most appropriate height was examined for the core sampling to assess pulpwood quality of Eucalyptus camaldulensis and E. globulus (age 14 years). Pulp properties considered were yield, sheet density, burst factor, breaking length, tear factor, folding endurance, unbleached brightness, and Kappa number and for wood properties, basic density, extracted basic density, wood chemical composition, extractives-free wood chemical composition, lignin syringyl:guaiacyl ratio, and neutral sugar mol% constituting hemicellulose were utilized. The most appropriate heights were 2.3-2.8 m above ground for E. camaldulensis, and 2.8 m for E. globulus against all pulp properties, and 2.8 m for both species against pulpwood productivity, and were concluded to be 2.8 m overall for both species. As a result, the whole-tree pulp properties and pulpwood productivity could be estimated using one increment core with chemical analysis of wood properties only.

Breeding trees for improved pulp and paper production : a review

Abstract: Traditionally breeders have improved growth, stem form, and branching. Breeding for improved wood, pulp, and paper properties can have a collective impact on harvesting, transport, and downstream processing costs, that is greater than the impact of increased growth on overall costs. Realized gains in growth and form, range from 10 to 40% per generation despite these traits being under relatively weak genetic control (h 2 c. 0.2). Wood quality traits are generally under stronger genetic control (h 2 = 0.4-0.8) allowing greater gains to be made. However these traits generally have lower coefficients of variation, assessing them is difficult and expensive, and sampling usually destroys the trees. Single point samples usually do not correlate well with whole tree values. Achieving greater gains in wood, pulp, and paper properties requires, defining the breeding objective more accurately and developing rapid, cheap, and effective assessment techniques, thereby permitting higher selection intensities and greater accuracy Determining the breeding objective is complex, involving assessing the impact of a unit change in each trait on costs and profit of the total process. Trade-offs associated with adverse genetic correlations require careful genetic and financial analysis. Adverse correlations are present between growth, and wood properties in radiata pine and possibly some Eucalypt species.

Genetic control and repeatability of near infrared reflectance from Eucalyptus nitens wood-meal

Abstract: Near infrared reflectance spectra (1100-2500 nm, in 700 discrete 2 nm bands) were captured (as the second derivative of the reflectance spectra) from woodmeal sampled from the outer growth rings of 588 7-year-old plantation grown Eucalyptus nitens trees. Heritability of reflectance across the spectra ranged from 0 to 0.35 (for a 10 band moving average). Repeatability of observed reflectance was consistently greater than 0.7 for wavelengths shorter than 2250 nm, but showed decline at longer wavelengths to a low 0.3 at 2500 nm. Bands showing high heritability showed low family by site interaction.

CIE whiteness and tint : possible improvements

Abstract: To introduce some measure of standardization in the face of the endless variety of whiteness formulae being used, the 'Commission internationale de l'eclairage' proposed in 1986 a whiteness and a tint formula for practical trials. The formulae in question were simplified derivatives of those used in the Ganz-Griesser method. The difference is that the CIE proposes fixed formula parameters and recommends the formulae only for relative assessments valid just for measurements with a single instrument at a given time and without reference to a white scale. Assessment with the formulae is appreciably improved if the sample illumination is stabilized and fitted as close as possible to a desired standard illuminant, as with the Gaertner-Griesser UV adjustment device. It also greatly improves the matching of different measuring instruments, though only for whiteness. The tint values can only be satisfactorily matched by instrument-specific calculation of the formula parameters as practised in the Ganz-Griesser method. The CIE method can be upgraded and markedly extended in scope by incorporating components of this new procedure, as suggested in the present paper. This takes account of the growing need to achieve a close match even between the results obtained with instruments of different designs.

Extensive analysis of strong black liquor

Abstract: Seventeen black liquor samples of different origin have been extensively analysed. Detailed data are presented for inorganic and organic compounds and for physical properties. New quantities describing the organic components have been introduced. A method for the determination of the molar mass disribution of polysaccharides is described. The content of polysacharides was much higher in liquors from soda and NSSC processes than from kraft pulping. Liquors from hardwood pulping were richer in high molar mass polysaccharides than liquors from softwood pulping. An increase in the content of high molar mass polysaccharides resulted in an increase in viscosity of the strong black liquor. The surface strength values for liquors at about, 50% dry solids content were higher than previously assumed. Liquor from a mill producing medium yield pulp (Kappa number 50) differed considerably from the liquor from mills producing bleachable pulp grades.

Comparative toxicity of effluents from ECF and TCF bleaching of eucalypt kraft pulps

Abstract: The toxicity of elemental chlorine free (ECF) and totally chlorine free (TCF) effluents from laboratory scale bleaching of eucalypt kraft pulps was compared using a suite of marine bioassays developed by the National Pulp Mills Research Program. The ECF bleaching sequence was D(EO)DD and the TCF sequences were Z(PO), (PA)P and (XQ)(EOP)(EPN)P. The effluents were tested before and after secondary treatment using Microtox, a phytoplankton growth inhibition test, a macroalgal fertilization test, a sea urchin fertilization test, a scallop larval abnormality test and a fish larval survival test. The untreated TCF effluents were more toxic than the ECF effluent, possibly due to residual peroxide in the TCF effluents. While secondary treatment reduced toxicity, both the ECF and one of the TCF effluents were still found to be toxic in the sensitive sea urchin fertilization and scallop larval abnormality tests. Environmental implications of these improvements in bleaching technology are discussed.

Effect of modified kraft pulping on enzyme assisted bleaching

Abstract: The effect of modified Kraft pulping was studied in the laboratory by treating radiata pine kraft and MCC pulps with several xylanase and mannanase preparations then observing the bleach response with a chlorine dioxide based DED sequence. MCC pulp contained lower proportions of residual hemicellulose than corresponding kraft pulp, suggesting less xylan redeposition occurred during modified pulping. MCC pulp was also less susceptible to xylanase, but not mannanase, attack. Enzyme treatments removed only a small proportion (<11%) of residual fibre bound hemicelluloses, with mannanase treatments giving the lowest levels. Assistance to bleaching was generally lower after enzyme treatment of MCC pulp than kraft pulp. Results suggested that only specific hemicelluloses located near the fibre surface are likely to be involved in enzyme-assisted bleaching. These hemicelluloses may include redeposited xylan and galactose rich glucomannan.

Comparison of refining response of eucalypt and a mixed hardwood pulp and their blends with softwood

Abstract: Different bleached market kraft pulps respond to refining in different ways. The response to refining of a mixed hardwood pulp, alone and in mixed hardwood/softwood blends, is examined and compared with that of a eucalypt pulp and pulp blends. The mixed hardwood pulp responds differently to refining, and has inferior strength and optical properties, compared with the eucalypt pulp. Mixed hardwood/softwood 80/20 blends have similar properties regardless of the fibre quality of the softwood component, as found previously for eucalypt/softwood blends. Mixed hardwood/softwood blends are weaker than corresponding eucalypt/softwood blends, but have equivalent optical properties. Mixed hardwood/softwood blends have freeness and strength properties similarly developed whether separately refined or co-refined at 0.5 W.s/m specific edge load. Co-refining at 1.5 W.s/m gave inferior results. Eucalypt/softwood blends have freeness and strength properties better developed after separate refining, with co-refining at 1.5 W.s/m giving better results than 0.5 W.s/m.

Bleaching of mechanical pulps with sodium bisulfite

Abstract: The use of sodium bisulfite as a substitute for dithionite in mechanical pulp bleaching or as an adjunct to other bleaching methods has been investigated using radiata pine and eucalypt pulps. Bisulfite bleaching can achieve similar brightness levels to dithionite bleaching at considerably greater reagent application. Reduced levels of applied bisulfite for bleaching of radiata pine pulps could be achieved by recycling bisulfite. Although the application level could be reduced up to 50% it was still unacceptably high. Sequential bisulfite-peroxide bleaching and peroxide-bisulfite bleaching gave marginal levels of brightness improvement which were soon lost through light induced reversion. UV-Vis reflectance and absorbance spectroscopy showed that various bleaching treatments affect different pulp chomophores. Peroxide affects both conferaldehyde and quinoid type chromophores whereas bisulfite predominantly affects the conferaldehyde types. Dithionite largely affects the quinoid type chromophores but the coniferaldehyde types also undergo reaction, probably with bisulfite formed on dithionite oxidation.

Kraft pulp qualities of eleven radiata pine clones

Abstract: The kraft pulp and fibre properties of eleven 16-year-old radiata pine clones are assessed. Kraft pulp qualities and chip basic density of individual trees are not correlated one with another in the clone population. Furthermore, handsheet properties of the clones are determined by the interactive influences of fibre length, coarseness and width, rather than by length and/or coarseness alone. The 11 clones contain fibres which are generally wide, large, and of high coarseness (wall area) and wall thickness when compared with seedling tree of radiata pine of the same age.

Texture image analysis for paper anisotropy and its variability

Abstract: Some operators from the theory of texture image analysis are used to obtain a new method for the evaluation of anisotropy in paper. A local gradient function provides information on local grammage, its anisotropy and its variability, from 2-dimensional grammage images captured by -radiography or light transmission. Results are reported for a series of papers displaying different levels of anisotropy. The method has potential for on-line application to monitoring and control because the new operator can extract similar information from both optical and radiographic images.

Environmental life cycle assessment of some new methods for producing bleached pulps from Australian eucalypt woods

Abstract: Bleached eucalypt kraft pulps manufactured in prospective Australian greenfield pulp mills with elemental chlorine free (ECF) and totally chlorine free (TCF) bleaching sequences were compared using life cycle assessment (LCA). The comparison was restricted to two wood resources from different geographical areas : plantation wood from Western Australia and mature wood from Northern Tasmania. The starting point of the study was the tree harvesting stage and the end point was dried pulp. The main differences between the cases were a result of the different pulp yields of mature and plantation wood. In the Tasmanian mature wood case, more wood and slightly more fossil fuel were needed, but more power was available for external use than in the Western Australian plantation case. The fossil fuel requirement was mainly for transport and wood harvesting. The pulp mills produced more effluent, emissions to air and solid waste than the wood harvesting or transport. However the contribution of the latter activity to certain air emissions and fossil fuel consumption was appreciable. There were minor differences between the ECF and TCF cases for each wood resource.

Multiple effect evaporator performance for black liquor. Part II: Development of improved steady state models

Abstract: Improved steady state models have been developed for the number 4 and 5, black liquor, multiple effect, evaporator sets at the Carter Holt Harvey Kinleith mill. The models were compared with plant data from the mill with average errors in the mass and energy balance predictions between 14 and 23%. The errors between the model predictions and the plant data were due largely to errors and inconsistencies in the plant data. In particular large boiling point rise errors in the plant data directly affected the accuracy of the calculated heat transfer coefficients. The number 4 set steady state model was used to evaluate two approaches for increasing the outlet concentration. i) Increasing the heat duty in effect 1. Increasing the steam temperature resulted in a higher outlet concentration for the same heat duty than increasing the heat transfer area. ii) Decreasing the feed liquor flow rate produced a higher concentration liquor than recycling a fraction of product liquor for the same decrase in feed liquor flow rate.

Development of TMP fibre and pulp quality

Abstract: The development of TMP quality is considered from the perspective of the long fibre fraction. When refined as a whole pulp, this long fibre both appears to develop in its papermaking performance at a similar rate to, and to form a less well consolidated network than the shorter fibre. As this long fibre is visually dominant in the paper surface, it is important that it receive additional, separate refining to improve its relative performance. Aspects of the achievement of freeness reduction by fibre cutting are examined, together with the quality implications of this for energy reduction achieved by increased refining intensity. Improvements in long fibre behaviour, when sulfonated as in the CTMP processes, are compared to that of TMP fibre.

The role of different alkalis in the deinking process

Abstract: The effect of deinking using various alkalis has been investigated. Magnesium oxide and ammonium hydroxide showed the same extent of ink removal as sodium hydroxide. The effect of sodium silicate varied with the different alkalis. Silicate free deinking was possible with some alkalis. Variations in the bleaching response of alkalis were observed at the pulping stage. However, due to the complexity of the system, these results were difficult to explain in relation to bleaching chemistry. Significant differences in the strength and optical properties of the pulps also occurred with different alkalis ; these differences can be explained by the hydrolysing effect of the alkalis.

Extended delignification of mature and plantation eucalypt wood. Part 2: The effects of chip impregnation factors

Abstract: The relative effects of a number of factors relating to pre-impregnation of the wood chips before conventional kraft cooking, conditions during the main part of the cook, and final treatments of the cooked chips before removal from the digester were evaluated in laboratory kraft pulping trials using a Plackett-Burman experimental design. Although a post-cook hot alkali wash of the chips appeared to have the greatest effect, none of the individual factors strongly influenced the critical properties of the pulps. However nearly all the pulps had higher strengths and yields than conventional pulps delignified to the same extent. Since the incorporation of an impregnation step was a common factor for all pulps, it is likely that the improvement in pulp properties is related in some way to this procedure.

Extended delignification of mature and plantation eucalypt wood. Part I: The principles of extended delignification

Abstract: Laboratory kraft pulping trials were carried out to characterize the effects on Australian mature and plantation eucalypts of each of four chemical principles of extended delignification - maintenance during pulping of an even alkali profile, provision of a high initial sulfide concentration, removal of dissolved lignin, and a low pulping temperature. The separate application of each of the four principles showed that the first three improve the pulp strength obtainable at a given Kappa number, while the beneficial effect of the fourth appeared limited to a small increase in pulp yield. The benefits gained from controlling the alkali level and dissolved lignin were substantially additive.

Totally chlorine-free (TCF) bleaching of radiata pine kraft pulp involving a UV-peroxide stage

Abstract: A commercial radiata pine kraft pulp was bleached with totally chlorine-free (TCF) sequences involving oxygen delignification (O), chelation (Q), alkali extraction (E), peroxymonosulfuric acid (Ps), peroxyformic acid (Pf), UV-peroxide (Up), and pressurized peroxide (PO) stages. Incorporation of a (Up) stage in the sequence OQ(Up)(PO) gave a pulp with brightness of 86% ISO. When two-stage oxygen delignification was introduced in the sequence OQ(PsO)(Up)(PO), ISO brightnesses up to 90% were achieved. A corresponding OQ(PsO)(PO)(PO) sequence gave a pulp with 83% brightness. Reduction in the alkali charge in the oxygen delignification stage of the sequence with a (Up) stage gave rise to pulps with lower brightnesses but with higher viscosities. The sequence (Pf)E(Up)(PO) applied to the kraft pulp yielded a pulp with 85% brightness but with reduced viscosity and yield. The pulp bleached with the elemental chlorine-free (ECF) sequence OD(EO) DD gave pulps with brightness up to 88%, and with higher viscosities and yields than the TCF pulps. The TCF pulps had fibre strengths lower than those of the ECF pulps, although the TCF pulps developed tensile strength more quickly on beating. The pulp bleached with the (Pf)E(Up)(PO) sequence had considerably lower fibre strengths than the ECF pulps. The results show that a (Up) stage can be used in a TCF sequence for bleaching radiata pine kraft pulp to high brightness.

The environmental impact of acidic shower water usage on the final stage of a brownstock washing system

Abstract: Using an acidic shower stream on the last stage of pulp washing is a method of increasing the level of chemical recovery in the kraft process. This effect occurs because the lowered pH environment causes sodium ions to desorb from the pulp fibres and thus become available for removal through washing. However, the effects of the acidic shower on the washing of organic materials are largely unknown. There are grounds for believing that an acidic shower would adversely affect the washing efficiency of organic materials (lignin). The effects of using acidic showers were investigated using a laboratory displacement cell washing apparatus. Pulp was washed using neutral shower water, acidic showers or 50/50 split applications of neutral and acidic showers. The results indicate that, while acidic showers make possible increased chemical recovery, they also increase the retention of bound organic materials with the pulp. Thus, the behavior of organic materials must be accounted for when considering using an acidic shower system.