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A modified process consisting of an initial mechanical refining (R) followed by a low-alkali (5.5% NaOH) cold caustic extraction (CCE) and finally an endoglucanase (EG) treatment (R-5.5%CCE-EG) was investigated for upgrading paper-grade pulp to dissolving pulp. Results showed that compared to the conventional process (9%CCE-EG), the modified process can decrease the alkali concentration (from 9% to 5.5%) to achieve a similar hemicelluloses removal while simultaneously enhancing the Fock reactivity (from 62.2% to 81.0%). The improved results were due to the fact that the mechanical refining resulted in favorable fiber morphological changes, including increased pore volume/size, water retention value and specific surface area. Consequently, the hemicelluloses removal was enhanced even under the subsequent low-alkali CCE condition. A synergic effect of refining, low alkali concentration and enzymatic activation was responsible for the higher reactivity of resulting dissolving pulp.

In this study we investigated the technical feasibility of convert paper mill sludge into fuel ethanol. This involved the removal of mineral fillers by using either chemical pretreatment or mechanical fractionation to determine their effects on cellulose hydrolysis and fermentation to ethanol. In addition, we studied the effect of cationic polyelectrolyte (as accelerant) addition and hydrogen peroxide pretreatment on enzymatic hydrolysis and fermentation. We present results showing that removing the fillers content (ash and calcium carbonate) from the paper mill sludge increases the enzymatic hydrolysis performance dramatically with higher cellulose conversion at faster rates. The addition of accelerant and hydrogen peroxide pretreatment further improved the hydrolysis yields by 16% and 25% (g glucose / g cellulose), respectively with the de-ashed sludge. The fermentation process of produced sugars achieved up to 95% of the maximum theoretical ethanol yield and higher ethanol productivities within 9h of fermentation.

For enzymatic treatment of dissolving pulp, there is a need to improve the process to facilitate its commercialization. For this purpose, the high consistency cellulase treatment was conducted based on the hypothesis that a high cellulose concentration would favor the interactions of cellulase and cellulose, thus improves the cellulase efficiency while decreasing the water usage. The results showed that compared with a low consistency of 3%, the high consistency of 20% led to 24% increases of cellulase adsorption ratio. As a result, the viscosity decrease and Fock reactivity increase at consistency of 20% were enhanced from 510 mL/g and 70.3% to 471 mL/g and 77.6%, respectively, compared with low consistency of 3% at 24h. The results on other properties such as alpha cellulose, alkali solubility and molecular weight distribution also supported the conclusion that a high consistency of cellulase treatment was more effective than a low pulp consistency process.

The effects of lime mud from papermaking process (LMP) addition as buffer agent and inorganic nutrient on the anaerobic digestion stability of food waste (FW) were investigated under mesophilic conditions with the aim of avoiding volatile fatty acids accumulation, and inorganic elements deficiency. When LMP concentration ranged from 6.0 to 10g/L, the FW anaerobic digestion could maintain efficient and stable state. These advantages are attributed to the existence of Ca, Na, Mg, K, Fe, and alkaline substances that favor the methanogenic process. The highest CH4 yield of 272.8mL/g-VS was obtained at LMP and VS concentrations of 10.0 and 19.8g/L, respectively, with the corresponding lag-phase time of 3.84d and final pH of 8.4. The methanogens from residue digestates mainly consisted of Methanobrevibacter, coccus-type and sarcina-type methanogens with LMP addition compared to Methanobacteria in control. However, higher concentration of LMP inhibited methanogenic activities and methane production.

A bench scale biofilter packed with compost and wood chips seeded with potential DMS degrading culture (Bacillus sphaericus) could efficiently remove DMS from ambient air with removal efficiency (RE%) of 71 ± 11 at an effective bed contact time (EBCT) of 360 ± 20 s with loading rate in the range of 4–28 gDMS/m3/h. Further, the same biofilter operated for the treatment of vent gas generated from a P&P industry indicated DMS removal of 61 ± 18% at optimal EBCT of 360 ± 25 s with a loading rate in the range of 3–128 gDMS/m3/h.

A new approach for the hydrophobization of finished cellulosic substrates based on a previously reported enzymatic technique is proposed. Commercial finished paper was hydrophobized by using laccase from Trametes villosa in combination with lauryl gallate (LG) as hydrophobic compound. The efficiency of the method was increased by the use of a lignosulfonate as a natural dispersant to improve the surface distribution of LG on the paper, raise its hydrophobicity and help preserve the enzyme activity. No similar threefold effect from a single compound for the improvement of enzymatic treatments was previously reported. The influence of processing conditions including the LG dose, treatment time and temperature was also examined, resulting in further increased hydrophobicity. Efficient fiber bonding and chemical functionalization were confirmed by thorough washing and Soxhlet extraction of the paper. As shown here for the first time, enzyme treatments have the potential to improve the surface hydrophobicity of paper-based media.

Vermistabilization of paper mill wastewater sludge (PMS) spiked with cow dung (CD) at ratios of 0%, 25%, 50%, 75%, and 100% was carried out employing the earthworm, Eisenia fetida. A total of five treatments were established and changes in chemical and microbial properties of mixtures were observed. Vermistabilization caused decreases in total organic carbon, C:N ratio and cellulose by 1.2-1.5, 4.6-14.6, and 2.3-9.7-fold, respectively, but increases in pH, electrical conductivity, ash content, (tot)N, (avail)P, (tot)P, (exch)K, Ca, Na, and N-NO(3)(-) of 1.06-1.11, 1.2-1.6, 1.3-1.6, 3.8-11.5, 4.1-6.5, 5.7-10.3, 1.7-2.0, 1.16-1.24, 1.23-1.45, 4.2-13.4-folds, respectively. PMS with 25-50% of CD showed the maximum mineralization rate. The fungal, bacterial and actinomycetes population increased 2.5-3.71, 3.13-8.96, and 5.71-9.48-fold, respectively after vermistabilization. The high level of plant-available nutrients indicates the suitability of vermistabilized material for agronomic uses.

The feasibility of cellulase recycling in the scope of bioethanol production from recycled paper sludge (RPS), an inexpensive byproduct with around 39% of carbohydrates, is analyzed. RPS was easily converted and fermented by enzymes and cells, respectively. Final enzyme partition between solid and liquid phases was investigated, the solid-bound enzymes being efficiently recovered by alkaline washing. RPS hydrolysis and fermentation was conducted over four rounds, recycling the cellulases present in both fractions. A great overall enzyme stability was observed: 71, 64 and 100% of the initial Cel7A, Cel7B and -glucosidase activities, respectively, were recovered. Even with only 30% of fresh enzymes added on the subsequent rounds, solid conversions of 92, 83 and 71% were achieved for the round 2, 3 and 4, respectively. This strategy enabled an enzyme saving around 53-60%, while can equally contribute to a 40% reduction in RPS disposal costs., The authors acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, COMPETE 2020 (POCI-01-0145-FEDER-006684) and the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462). The financial support of FCT through GlycoCBMs Project PTDC/AGR-FOR/3090/2012–FCOMP-01-0124-FEDER-027948 and the PhD grant to DG (SFRH/BD/88623/2012) is equally acknowledged. The authors also thank RENOVA (Portugal) for kindly providing the recycled paper sludge.

A mixed culture of microalgae, containing two Scenedesmus species, was analysed to determine its potential in coupling of pulp and paper mill effluent treatment and microalgal cultivation. Laboratory studies suggested that 60% concentration of wastewater was optimum for microalgal cultivation. A maximum of 82% and 75% removal of BOD and COD respectively was achieved with microalgal cultivation in outdoor open pond. By the end of the cultivation period, 65% removal of NO3-N and 71.29% removal of PO4-P was observed. The fatty acid composition of mixed microalgal culture cultivated with effluent showed the palmitic acid, oleic acid, linoleic acid and α-linolenic acid as major fatty acids. The results obtained suggest that pulp and paper mill effluent could be used effectively for cultivation of microalgae to minimise the freshwater and nutrient requirements.

The conversion of paper-grade pulps into dissolving pulps requires efficient strategies and process steps to remove low-molecular noncellulosic macromolecules generally known as hemicelluloses. Current strategies include alkaline extractions and enzymatic treatments. This study focused on the evaluation of extraction efficiencies in alkaline extractions of three economically interesting hardwood species: beech (Fagus sylvatica), birch (Betula papyrifera), and eucalyptus (Eucalyptus globulus). Substrate pulps were subjected to alkaline treatments at different temperatures and alkalinities using white liquor as the alkali source, followed by analyses of both pulps and hemicellulose-containing extraction lyes. The extracted hardwood xylans have strong potential as an ingredient in the food and pharmaceutical industries. Subsequent analyses revealed strong dependencies of the extraction efficiencies and molar mass distributions of hemicelluloses on the process variables of temperature and effective alkalinity. The hemicellulose content of the initial pulps, the hardwood species, and the type of applied base played minor roles.

Eucalyptus globulus sapwood and heartwood showed no differences in lignin content (23.0% vs. 23.7%) and composition: syringyl-lignin (17.9% vs. 18.0%) and guaiacyl-lignin (4.8% vs. 5.2%). Delignification kinetics of S- and G-units in heartwood and sapwood was investigated by Py-GC–MS/FID at 130, 150 and 170 °C and modeled as double first-order reactions. Reactivity differences between S and G-units were small during the main pulping phase and the higher reactivity of S over G units was better expressed in the later pulping stage. The residual lignin composition in pulps was different from wood or from samples in the initial delignification stages, with more G and H-units. S/G ratio ranged from 3 to 4.5 when pulp residual lignin was higher than 10%, decreasing rapidly to less than 1. The S/H was initially around 20 (until 15% residual lignin), decreasing to 4 when residual lignin was about 3%.

Nine phenol derivatives, p-coumaric acid (PC), vanillin (V), acetovanillone (AV), acetosyringone (AS), syringaldehyde (SA), coniferaldehyde (CLD), ferulic acid (FRC), sinapic acid (SNC), and sinapyl aldehyde (SLD) were assayed as laccase redox mediators in the biobleaching of kenaf and sisal pulps. As a general behaviour, the phenolic mediators increased the kappa number (KN) and reduced the brightness of pulps. In particular, these changes were found to depend in a linear manner on the energy of the highest occupied molecular orbital (EHOMO) of the mediators. The phenolic mediator with the lowest EHOMO (PC) led to the highest increase of KN and the lowest reduction of brightness. On the contrary, syringyl derivatives (i.e. SA) with high EHOMO values caused small KN increases and significant losses of brightness. This behaviour was explained on the basis of a competition between grafting and polymerisation processes. The former basically affects KN, whereas the latter affects pulp brightness.

Corn stalk pretreated with white-rot fungus Trametes hirsute was used to produce fiberboard by hot pressing without adhesive. The moduli of rupture and elasticity of the corn-stalk-based fiberboard were increased 3.40- and 8.87-fold when bio-pretreated rather than untreated corn stalk was used. Fourier transform infra-red spectroscopy, X-ray diffraction, and chemical analysis showed that bio-pretreated corn stalk increased the mechanical properties of the fiberboard because it had more than twice the number of hydroxyl group, an 18% higher crystallinity, and twice the polysaccharide content of untreated corn stalk. Its laccase content was 4.65 ± 0.38 U/g. Corn stalk-based fiberboard production did not require adhesives, thus eliminating a potential source of toxic emissions such as formaldehyde gas.

Although the moderate load (COD of 5000-10,000 mg/L) and biodegradability of the APMP pulping effluent should allow biological treatment, toxic compounds in the effluent can interfere with this type of treatment. Studies were conducted to determine if treatment of the effluent with Aspergillus niger S13 was feasible. Under the optimized conditions (3% inoculum, pH 6, shaking at 160 rpm, 60-72 h, and 30°C), this fungus was able to remove about 97% of the methyl tertiary butyl ether (MTBE) extractives, and 60%, 77% and 43% of the chemical oxygen demand, turbidity and color even without a pre-flocculation step. These results are of practical interest in China because the APMP process has become popular, and efficient and cost-effective effluent treatment technologies are in high demand.

This study deals with the decolorization of black liquor (BL) by isolated potential bacterial consortium comprising Serratia marcescens (GU193982), Citrobacter sp. (HQ873619) and Klebsiella pneumoniae (GU193983). The decolorization of BL was studied by using the different nutritional as well as environmental parameters. In this study, result revealed that the ligninolytic activities were found to be growth associated and the developed bacterial consortium was efficient for the reduction of COD, BOD and color up to 83%, 74% and 85%, respectively. The HPLC analysis of degraded samples of BL has shown the reduction in peak area compared to control. Further, the GC-MS analysis showed that, most of the compounds detected in control were diminished after bacterial treatment while, formic acid hydrazide, 4-cyclohexane-1,2-dicarboxylic acid, carbamic acid, 1,2-benzenedicarboxylic acid and erythropentanoic acid were found as new metabolites. Further, the seed germination test using Phaseolus aureus has supported the detoxification of bacterial decolorized BL.

A novel two-stage biological/flocculation process was developed for treating the pulping effluent from the alkaline peroxide mechanical pulping (APMP) process. In the first biological stage, the aerobic fermentation by using Aspergillus niger can decrease the chemical oxygen demand (COD) by about 60% while producing about 7 g/l of solid biomass. In the second stage (post-coagulation/flocculation), the residual COD, turbidity and color, can be further decreased by using alum and polyacrylamide (PAM). The overall removal efficiencies of COD, color and turbidity from the APMP pulping effluent by the above two-stage biological-coagulation/flocculation process were 93%, 92% and 99%, respectively, under the conditions studied.

Poplar chips were pre-treated by Trametes versicolor for 1, 2 and 3 weeks. Pre-treated chips, after washing, have been air dried for kraft pulping to achieve pulp kappa number of about 20. Pulp samples have been analyzed by Bauer Mc Nett, Kajaani analyzer and SEM. The results indicated that fungi pre-treatment of chips can degrade lignin and carbohydrates and affect kraft pulping and fiber characteristics. Higher chemical charge in pulping, lower fine and higher long fiber fraction were observed in pre-treated pulp samples in comparison with others. Fiber length, cross sectional area, width, cell wall thickness and volume index were increased by increasing pre-treatment time while fine length, fiber coarseness and curl have been reduced. Based on the study findings, with respect to higher fiber length, lower fine, and lower fiber curl and coarseness, 2-weeks pre-treatment of chips was recommended to produce acceptable overall fiber properties in kraft pulping.

A comparable series of specimens from spruce wood were pre-treated with sodium hydroxide, sodium hydroxide and hydrogen peroxide, or per-acetic acid sequences. The pre-treatments reduced the yield of pulps and their Kappa number noticeably, diminished the degree of polymerization moderately, and increased their brightness. One-step peroxide bleaching of pulps from the pre-treated spruce wood resulted in their higher brightness compared to bleached pulp from sound wood. From the viewpoint of improved properties of pulp, the most efficient were the sodium hydroxide/per-acetic acid and per-acetic acid/sodium hydroxide sequences. The pre-treatments did not influence mechanical strength of the obtained pulps significantly.

This work seeks the integral use of all major components of Hesperaloe funifera , separating hemicelluose by hydrothermal treatments; cellulose by pulping processes; and exploitation of lignin of pulping liquor by pyrolysis and gasification processes. By using sulfuric acid in the hydrothermal treatment (150–190 °C, 0–20 min after reaching operating temperature, 6–10 liquid/solid ratio, 0.1–0.5% sulfuric acid), the glucose and xylose of liquid fraction increase from 1.5% to 5.9%, and 4.0% to 12.4%, respectively; the yields of solid fraction decrease from 91.6% to 79.5%, and the lignin content increase from 23% to 32%. Pulps and paper sheets obtained from solid fractions hydrothermal treatments and from raw material pulped with diethanolamine, are worse than those obtained with soda–anthraquinone (Yield 57.8%; kappa number 24.9; Viscosity 711 mL/g; Brightness 54.8%; Tensile index 73.6 Nm/g; Stretch 2.84%; Burst index 6.13 kN/g and Tear index 1.69 mNm 2 /g). By acidification (pH 6) of soda pulping liquor it separate lignin-rich solids, which by pyrolysis gave a gas containing 1.13% H 2 , 31.79% CO and 1.86% CH 4 by weight. Gasification of the same sample provided a gas containing 0.18% H 2 , 24.50% CO and 17.75% CH 4 .

A sequence of treatments consisting of an initial xylanase treatment followed by cold alkaline extraction and a final endoglucanase treatment was investigated as a process for upgrading non-wood paper-grade pulps to dissolving-grade pulps for viscose production. Five commercial dried bleached non-wood soda/AQ paper pulps, from flax, hemp, sisal, abaca, and jute, were studied for this purpose. Commercial dried bleached eucalyptus dissolving pulp was used as reference sample. Sisal pulp showed the highest improvement in Fock's reactivity, reaching levels nearly as high or even higher than that of eucalyptus dissolving pulp (65%), and a low hemicellulose content (3-4%) when was subjected to this sequence of treatments. The viscosity, however, decreased considerably. A uniform and narrow molecular weight distribution was observed by size exclusion chromatography. (13)C nuclear magnetic resonance spectroscopy and Raman microspectroscopy revealed that the cellulose structure consisted of cellulose I.

a)Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, PO Box 1052, E-41080 Seville, Spain b)University of Aveiro, CICECO, 3810-193, Aveiro, Portugal c)Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Oxidation of the manganese-substituted polyoxometalate [SiW11MnII(H2O)O39]6- (SiW11MnII) to [SiW11MnIII(H2O)O39]5-, one of the most selective polyoxometalates for the kraft pulp delignification, by versatile peroxidase (VP) was studied. First, SiW11MnII was demonstrated to be quickly oxidized by VP at room temperature in the presence of H2O2 (Km= 6.4±0.7 mM and kcat= 47±2 s-1). Second, the filtrate from eucalypt pulp delignification containing reduced polyoxometalate was treated with VP/H2O2, and 95-100% reoxidation was attained. In this way, it was possible to reuse the liquor from a first SiW11MnIII stage for further delignification, in a sequence constituted by two polyoxometalate stages, and a short intermediate step consisting of the addition of VP/H2O2 to the filtrate for SiW11MnII reoxidation. When the first ClO2 stage of a conventional bleaching sequence was substituted by the two-stage delignification with polyoxometalate (assisted by VP) a 50% saving in ClO2 was obtained for similar mechanical strength of the final pulp., This study has been supported by the EU project BIORENEW (NMP2-CT-2006-026456) and the Spanish projects AGL2008-00709 and BIO2008-01533.

Miscanthus x giganteus bark samples subjected to fractionation by the Acetosolv process under optimal conditions were bleached using hydrogen peroxide and acetic acid in aqueous media under alkaline conditions. The influence of the main operational variables in the bleaching of Acetosolv pulps of M. x giganteus (i.e. hydrogen peroxide concentration, 3–7%; temperature, 55–75 °C; pH 9–11), obtained after treatments, have been assessed on pulp yield, kappa number, viscosity and brightness of bleached pulps. For this purpose, a rotatable and orthogonal second-order factorial design of experiments was used, in order to identify the optimum operating conditions. The obtained empirical mathematical models demonstrate that, in general, the bleaching was efficient, achieving pulps with kappa numbers below 10. The chemical composition and physicochemical properties of the bleached pulps fulfilled the requirements for forthcoming bleaching stages. Moreover, an alkaline extraction stage to eliminate saponifiable groups of Acetosolv pulps was studied, as well as the necessity of use chelating agents in the stage with hydrogen peroxide.

The objective of this research was to develop an integrated process to produce biogas and high-quality particleboard using saline creeping wild ryegrass (CWR), Leymus triticoides through anaerobic digestion (AD). Besides producing biogas, AD also serves as a pretreatment method to remove the wax layer of CWR for improving binding capability and then the residue is used to produce high-quality particleboard. CWR was digested for three time periods, 15, 22, and 33 days with the volatile solid (VS) loading of 10 g-VS/L-sludge and the food to microorganism (F/M) ratio of 1.41. The highest biogas yield after digestion for 33 days was 251 mL/g-VS, which is corresponded to energy of 8419 BTU/kg-dry CWR. The highest methane content of biogas was 63%. Compared with particleboards manufactured from urea formaldehyde (UF) and untreated CWR, the mechanical and long-term (24 h) water resistance properties of particleboards made from UF and 33-day AD CWR residue were statistically significantly improved, except for modulus of elasticity (MOE). For example, the modulus of rupture (MOR) was increased by 39%. The results indicated that the integrated process could be a cost-effective and environmentally friendly method for producing bioenergy and particleboard with agricultural residues.

White-rot fungus Trametes hirsute ( T.h. 19-6) was used for modifying the eucalyptus CTMP fibres. Results show that the T.h. 19-6 removed mainly lignin (by 7.42%) and extractive (by 11.52%) after a short period of 5 days incubation. Due to the fungal degradation of the fibre wall materials, the middle lamella remainder on the fibre surface was significantly reduced and the fibre wall structure was loosened, which led to an increase in fibre internal bonding strength by 32% and an increase in handsheet tensile index and tear index by 49%, and 34%, respectively. A subsequent PFI refining process further amplified the fungal treatment effect, resulting in extensive fibre internal fibrillation. Compared with untreated pulp, fungus-treated pulp reached the same freeness levels with less PFI revolutions, indicating potential energy saving in the refining process.

In this work, depithed cardoon stalk (Cynara cardunculus) has been used with the objective of obtaining bleachable pulps. The material, once properly prepared, was subjected to one-step peroxyformic acid delignification. In order to study the process, a face-centred second order factorial design was developed which allowed the determination of the influences of four variables: concentrations of formic acid and hydrogen peroxide in the cooking liquor and the time and temperature of the treatment. Empirical mathematical models have been obtained which predict the yield, kappa index, residual lignin content, and viscosity of the pulps. These models demonstrate that in general the delignification was extensive, producing pulps with kappa indexes less than 25 in the majority of cases, with good yields in the range of 45-60%. However, the pulps seem to have been degraded in the reaction media, as can be deduced from the low viscosity values found: 260-520 mL/g.

A bioflocculant-producing bacterium was isolated from soil and identified as Serratia ficaria . Using optimized culture conditions a flocculating activity of 95.4% was obtained. It was found to be effective for flocculation of a kaolin suspension over weakly acidic pH (5–7); divalent cations (Ca 2+ and Mg 2+ ) enhanced the flocculating activity, while the co-presence of Al 3+ and Fe 3+ resulted the negative effect. Measurements of zeta potential revealed that charge neutralization played an important role in the flocculation. It could flocculate a variety of real wastewaters, including river water, brewery wastewater, meat processing wastewater and soy sauce brewing wastewater. The bioflocculant was also used to treat pulp effluent, and the removal rate of color and chemical oxygen demand (COD) were up to 99.9% and 72.1%, respectively, which were better than traditional chemical flocculants.

The purpose of this study was to produce recombinant xylanase in transgenic plants and to test its potential application for pulp bleaching. The xynII xylanase gene from Trichoderma reesei was inserted into the Arabidopsis genome. Many transgenic plants produced biologically active XYNII and accumulated in leaves at level of 1.4-3.2% of total soluble proteins. The bleaching ability of XYNII on Kraft pulp was demonstrated by a reduction in the kappa number and the residual lignin contents. The bleaching efficiency of transgenic plant produced XYNII was similar to commercial xylanase on unbleached Kraft pulp. The effect of xylanase treatment on Kraft pulp was also investigated by SEM. Clear physical change on the pulp fiber surface was observed and was related to the amount xylan removed and microfibrils were visible on the fiber surface. This report demonstrates the potential application of plant produced recombinant xylanase for pulp and paper bleaching.

We studied the influence of the operational variables (viz. ethylene-glycol concentrations of 50–70%, temperatures of 155–185 °C, times of 30–90 min and numbers of PFI beating revolutions of 500–1500) on pulp yield and various paper properties (breaking length, stretch, burst index, tear index and brightness) obtained in the ethylene-glycol pulping of vine shoots, cotton stalks, leucaena ( Leucaena leucocephala ) and tagasaste ( Chamaecytisus proliferus ). The fuzzy neural network models used reproduced the experimental results with errors less than 15% and smaller than those provided by second-order polynomial models in all cases. An ethylene-glycol concentration of 65% at 180 °C for 75 min and 1500 PFI beating revolutions were found to provide substantial savings in energy, chemicals and facility investments as a result of operating under milder conditions than the strongest ones studied in this work. Tagasaste was found to be the most suitable raw material among those tested as it provided the paper sheets with the highest breaking length (4644 m), stretch (2.87%), burst index (2.46 kN/g), tear index (0.33 m Nm 2 /g) and brightness (40.92%); its pulp yield was also high (62.88%), which reflects efficient use of this raw material.

In this work, we studied the influence of operational variables in the bleaching of soda pulp of Musa textilis nee (abaca) [viz. temperature (55-85 degrees C), bleaching time (30-150 min) and peracetic acid concentration oven dry pulp (0.5-4.5%)] on the kappa number and viscosity of the bleached pulp, as well as on the breaking length, burst index and brightness of paper sheets made from it. For this purpose, we used a central composite factorial design in order to identify the optimum operating conditions. In this way equations relating the dependent variables to the operational variables of the bleaching process were derived. These equations reproduce the dependent variables with errors less than 12% for all, except the viscosity which was predicted with errors less than 18%. Obtaining bleached pulp with the highest possible viscosity (1519 ml/g), and paper sheets with the maximum possible breaking length (6547 m) and burst index (5.00 kN/g), entails using a temperature of 55 degrees C, a peracetic acid concentration of 4.5% and a bleaching time of 150 min. This provides a brightness of 79.90%, which is only 6.53% lower than the maximum possible value (85.48%).

To study the possibility of some residues from pulp and paper industry being used as substrates to produce seedlings in containers, three composting experiments were carried out using eucalyptus bark, pine bark and a mixture (60:40, v:v) of pine bark+eucalyptus bark. Biochemical parameters studied were: acid and alkaline phosphatases, lipase (C10), protease, urease, beta-glucosidase and total cellulases. The microbiological populations of total aerobic bacteria, total fungi, actinomycetes, nitrifying bacteria, cellulolytic bacteria and fungi were also evaluated. At the end of the process physicochemical characterization of composts was also performed. Results showed in general that the highest microbiological populations as well as for enzymatic activities occurred during the thermophilic phase (40 degrees C) of the process. On the other hand and according to the physicochemical characteristics of composts pine bark is the most appropriate material to be used in the formulation of substrates to produce plants in containers.

The present study aimed at optimization of culture condition for the enhanced production of extra cellular thermostable cellulase-free xylanase from Bacillus pumilus by solid-state fermentation. Batch studies were carried out to evaluate various agro-industrial residues such as rice bran, rice husk, rice straw, sawdust, coconut pith, sugarcane bagasse and wheat bran for enzyme production by the bacterial culture. The endoxylanase production was highest on wheat bran media (5582 U/gds), which was enhanced 3.8-fold (21,431 U/gds) by optimization of cultivation conditions. The enzymatic extracts was used in mixed wastepaper recycling, which resulted in a considerable improvement of the paper strength with high drainage and easy drying up. The results of enzyme application with recycled paper clearly indicated that the effective use of enzymes in fiber separation could reduce the cost of carton paper production.

There has been increasing interest in extracellular enzymes from white rot fungi, such as lignin and manganese peroxidases, and laccases, due to their potential to degrade both highly toxic phenolic compounds and lignin. The optimum cultivation conditions for laccase production in semi-solid and liquid medium by Trametes versicolor, Trametes villosa, Lentinula edodes and Botrytis cinerea and the effects of laccase mediator system in E1 effluent were studied. The higher laccase activity (12756 U) was obtained in a liquid culture of T. versicolor in the presence of 1 mM of 2,5-xylidine and 0.4 mM copper salt as inducers. The effluent biotreatments were not efficient in decolorization with any fungal laccases studied. Maximum phenol reduction was approximately 23% in the absence of mediators from T. versicolor. The presence of 1-hydroxybenzotriazole did not increase phenol reduction. However, acetohydroxamic acid, which was not degraded by laccase, acted very efficiently on E1 effluent, reducing 70% and 73% of the total phenol and total organic carbon, respectively. Therefore, acetohydroxamic acid could be applied as a mediator for laccase bioremediation in E1 effluent.

Paper mill sludge (PS), a solid waste from pulp and paper industry, was investigated as a feedstock for acetone-butanol-ethanol (ABE) production by simultaneous saccharification and fermentation (SSF). ABE fermentation of paper sludge by Clostridium acetobutylicum required partial removal of ash in PS to enhance its enzymatic digestibility. Enzymatic hydrolysis was found to be a rate-limiting step in the SSF. A total of 16.4-18.0g/L of ABE solvents were produced in the SSF of de-ashed PS with solid loading of 6.3-7.4% and enzyme loading of 10-15FPU/g-glucan, and the final solvent yield reached 0.27g/g sugars. No pretreatment and pH control were needed in ABE fermentation of paper sludge, which makes it an attractive feedstock for butanol production. The results suggested utilization of paper sludge should not only consider the benefits of buffering effect of CaCO3 in fermentation, but also take into account its inhibitory effect on enzymatic hydrolysis.

The eicosapentaenoic acid (EPA) containing marine microalga Nannochloropsis oculata was grown in an effluent from anaerobic digestion of excess activated sludge from a wastewater treatment plant serving a combination of a pulp and a paper mill and a municipality (digester effluent, DE), mixed with the effluent of the same wastewater treatment plant. The maximum specific growth rate and photosynthesis of N. oculata were similar in the DE medium and in artificial sea water medium (ASW) but after 7 days, algae grown in the DE medium contained seven times more triacylglycerols (TAGs) per cell than cells grown in ASW, indicating mild stress in the DE medium. However, the volumetric rate of EPA production was similar in the ASW and DE media. The results suggest that N. oculata could be used to produce EPA, utilizing the nutrients available after anaerobic digestion of excess activated sludge of a pulp and paper mill.

Cellulase treatment for decreasing viscosity and increasing Fock reactivity of dissolving pulp is a promising approach to reduce the use of toxic chemicals, such as hypochlorite in the dissolving pulp manufacturing process in the industry. Improving the cellulase treatment efficiency during the process is of practical interest. In the present study, the concept of using cationic polyacrylamide (CPAM) to enhance the cellulase treatment efficiency was demonstrated. This was mainly attributed to the increased cellulase adsorption onto cellulose fibers based on the patching/bridging mechanism. Results showed that the cellulase adsorption was increased by about 20% with the addition of 250 ppm of CPAM under the same conditions as those of the control. It was found that the viscosity decrease and Fock reactivity increase for the cellulase treatment was enhanced from using CPAM. The CPAM-assisted cellulase treatment concept may provide a practical alternative to the present hypochlorite-based technology for viscosity control in the industry.

An alkalistable endoxylanase from Streptomyces cyaneus SN32 was applied in bleaching of wheat straw enriched soda pulp. The xylanase dose of 10 IUg(-1) moisture free pulp exhibited maximum bleach boosting of soda pulp (pH 9.5-10.0) optimally at 65 degrees C after 2 h of reaction time. Pre-treatment of pulp with xylanase and its subsequent treatment with 6% hypochlorite reduced the kappa number by 8.7%, enhanced the brightness index by 3.56% and improved other paper properties such as tear index and burst index. The enzymatically-prebleached pulp when treated with 10% reduced level of hypochlorite (5.4%) gave comparable brightness of resultant hand sheets to the fully bleached pulp (6% hypochlorite).

Gluconic acid production was investigated using an enzymatic hydrolysate of waste office automation paper in a culture of Aspergillus niger. In repeated batch cultures using flasks, saccharified solution medium (SM) did not show any inhibitory effects on gluconic acid production compared to glucose medium (GM). The average gluconic acid yields were 92% (SM) and 80% (GM). In repeated batch cultures using SM in a turbine blade reactor (TBR), the gluconic acid yields were 60% (SM) and 67% (GM) with 80-100 g/l of gluconic acid. When pure oxygen was supplied the production rate increased to four times higher than when supplying air. Remarkable differences in the morphology of A. niger and dry cell weight between SM and GM were observed. The difference in morphology may have caused a reduction of oxygen transfer, resulting in a decrease in gluconic acid production rate in SM.

Knowledge of the microbiology of dinitrogen (N2)-fixing bacteria in compost rich in de-inking paper sludge (DPS) is limited. Dinitrogen (N2)-fixing bacteria from DPS composts were isolated and studied for their N2-fixing activity in vitro and in vivo. Two Gram-negative N2-fixing isolates were identified as Pseudomonas. At 20 degrees C, both isolates revealed that N2-fixing activity was higher than that of three arctic Pseudomonas strains. Their N2-fixing activity was found to occur between 18 and 25 degrees C, a pattern that was similar to the reference isolate Azotobacter ATCC 7486. Composts successfully showed N2-fixing activity after carbohydrate amendments both with and without inoculation of a N2-fixing isolate. These results suggest that DPS composts support N2-fixing bacteria and that N2-fixing activity is dependent on a usable carbohydrate source.

Four eucalypts (Eucalyptus camaldulensis, Eucalyptus microtheca, Eucalyptus tereticornis and Eucalyptus citriodora) grown in Sudan were examined for their suitability for pulping and papermaking with different alkaline methods. Their physical, morphological and chemical characteristics are reported. The pulping trials with E. citriodora and E. tereticornis were carried out using the kraft-AQ, soda-AQ, modified AS/AQ (ASA), ASAM and kraft methods. For the other two species, only the ASAM and the kraft process were applied. ASAM pulping gave the best results in terms of yield, degree of delignification, mechanical and optical pulp properties. The best pulps, obtained in kraft and ASAM cooking of E. citriodora, were bleached to 88% ISO brightness in a totally chlorine free bleaching sequence (OQ1O/PQ2P). The bleached pulps, especially the ASAM pulp, showed good papermaking properties and would be suitable for manufacture of writing and printing grades of paper.

A comparative study on TCF (totally chlorine-free) bleachability of organosolv pulps from the annual fibre crop Arundo donax L. (giant reed) was carried out using a simple three-stage peroxide bleaching sequence without oxygen pre-bleaching. ASAM (alkali-sulfite-anthraquinone-methanol), Organocell (alkali-anthraquinone-methanol) and ethanol-soda organosolv pulps were bleached and compared with kraft pulp, as a reference. The final brightness of 76-78% ISO was attained for all tested pulps. The chemical charge required to reach this level of brightness varied for different pulps (despite the equal initial content of the residual lignin) and directly related to starting brightness values. No direct correlation between brightness improvement and lignin removal during bleaching was found, indicating the influence of the specific pulp properties introduced by pulping process on bleaching chemistry. The general higher bleaching response of organosolv pulps from A. donax was noted in comparison with kraft.

The performance of four species of earthworm––Eudrilus eugeniae, Kinberg, Drawida willsi Michaelsen, Lampito mauritii, Kinberg and Perionyx excavatus, Perrier––born and grown in vermireactors fed with paper waste was studied over six months, in terms of vermicast output per unit feed, production of offspring, and increase in worm zoomass. These were compared with the performance of the previous generation which had been raised to adulthood on cowdung as principal feed before shifting them to vermireactors operating on cowdung-spiked paper waste. The results indicated that except with D. willsi of which the second generation performed only a shade better than the first, there was significant improvement in vermicast output, animal growth, and reproduction in the second generation compared to the first. The results indicated that cowdung-spiked paper waste can be an adequate food for successive generations of earthworms and that reactors can be operated indefinitely on this feed. The results also indicated that the earthworm generations born and raised in vermireactors operated on this feed become better vermiconverters of this feed than the parent earthworms.

The cultivation conditions for Rhizopus oryzae grown in synthetic medium and paper pulp spent sulfite liquor (SSL) were investigated to achieve high biomass and ethanol yields using shake flasks and bioreactors. The fungus assimilated the hexoses glucose, mannose and galactose, and the pentoses xylose and arabinose as well as acetic acid which are present in SSL. The assimilation of hexoses was faster than pentoses during cultivation in a synthetic medium. However, all sugars were assimilated concomitantly during growth in SSL supplemented with ammonium, magnesium, calcium, phosphate, sulfate and trace amounts of some other metal ions (SSL-S). The medium composition had an important influence on biomass yield. The highest biomass yields, viz. 0.18 and 0.43 g biomass/g sugar were obtained, when the cells were cultivated in shake flasks with a synthetic medium containing glucose as carbon and energy source and SSL-S, respectively. The corresponding yields in a bioreactor with more efficient aeration were 0.22 and 0.55 g/g. In addition to the biomass, ethanol, lactic acid, and glycerol were important extracellular metabolites of the cultivation with maximum yields of 0.37, 0.30 and 0.09 g/g, respectively. When the source of sugars in the medium was exhausted, the fungus consumed the metabolites produced, such that the liquid medium was depleted of potential oxidizable nutrients. In general, there was a direct competition between lactic acid and ethanol among the metabolites. Poor medium compositions and cultivation conditions resulted in higher yields of lactic acid, whereas the ethanol and biomass yields were higher in rich media. SSL-S supported good growth of mycelium and a high ethanol yield.

An alkalophilic Aspergillus nidulans KK-99 produced an alkaline, thermostable xylanase (40 IU/ml) in a basal medium supplemented with wheat bran (2% w/v) and KNO3 (at 0.15% N) pH 10.0 and 37 degrees C. The partially purified xylanase was optimally active at pH 8.0 and 55 degrees C. The xylanase was stable in a broad pH range of 4.0-9.5 for 1 h at 55 degrees C, retaining more than 80% of its activity. The enzyme exhibited greater binding affinity for xylan from hardwood than from softwood. The xylanase activity was stimulated (+25%) by Na+ and Fe2+ and was strongly inhibited (maximum by 70%) by Tween-20, 40, 60, SDS, acetic anhydride, phenylmethane sulphonyl fluoride, Triton-X-100. The xylanase dose of 1.0 IU/g dry weight pulp gave optimum bleach boosting of Kraft pulp at pH 8.0 and temperature 55 degrees C for 3 h reaction time.

In this study, the ability of algae to treat a wood-based pulp and paper industry wastewater was investigated. Tests were performed in batch reactors seeded with a mixed culture of algae. Under different lighting and initial wastewater strength conditions, changes in COD, AOX and color contents of reactors were followed with time. Algae were found to remove up to 58% of COD, 84% of color and 80% of AOX from pulp and paper industry wastewaters. No remarkable differences were observed in COD and color when light intensity and wastewater strength were changed, while AOX removals were strongly affected. Algal species identification studies revealed that some green algae (Chlorella) and diatom species were dominant in the treatment. The study also showed that algae grew mixotrophically, while the main mechanism of color and organics removal from pulping effluents was partly metabolism and partly metabolic conversion of colored and chlorinated molecules to non-colored and non-chlorinated molecules. Adsorption onto algal biomass was not so effective.

Paper waste, spiked with varying proportions of cowdung, was vermicomposted in `low-rate' and `high-rate' reactors. The former type of reactors had earthworm populations and feed loading rates similar to ones recommended by previous workers. The `high-rate' reactors were operated with 12.5 times higher earthworm densities and feed loading rates. All the reactors were studied for six months to assess the vermicast output, survivability, growth and reproduction of the earthworms – hence the sustainability of the reactors – for long-term, continuous operation. The studies revealed the viability of the high-rate vermireactor concept. The high-rate reactors consistently produced over 6.5 times more castings per unit digester volume with no adverse effect on the earthworm population, as reflected by (a) absence of mortality, (b) consistent growth in worm zoomass, and (c) normal rate of reproduction. The studies also revealed that an increase in the cowdung fraction in the feed from 14.3% to 20% (4:1 paper:cowdung blends to 6:1 blends) had little positive impact on the vermicast output or earthworm health. This indicated that spiking of paper feed with ∼14% cowdung, or perhaps an even smaller fraction, might be adequate to support earthworms in the paper-fed vermireactors.

When the wild type Cellulomonas flavigena was grown on glycerol, xylose or cellobiose, it produced basal levels of carboxy-methyl-cellulase (CMCase), filter-paperase (FPase) and xylanase activities. By comparison, a catabolic derepressed mutant strain of the same organism produced markedly higher levels of these enzymes when grown on the same carbon sources. Sugar-cane bagasse induced both the wild type and the mutant strain to produce three- to eight-time higher levels of FPase and xylanase than was observed with xylose or cellobiose. Continuous culture was used to determine the minimal cellobiose or glucose concentrations that repress the enzyme synthesis in both strains. 2.5 g l −1 glucose repressed FPase and xylanases from wild type, while 1.6 times more glucose was needed to repress the same activities in the PN-120 strain. In the same way, twofold more cellobiose was needed to reduce by 75% the CMCase and xylanase activities in the mutant compared to the wild type. The FPase in the presence of 4 g l −1 cellobiose did not change in the same strain. Therefore, its derepressed and feedback resistant characters of PN-120 mutant are evident. On the other hand, isoelectrofocused crude extracts of mutant and wild strains induced by sugar-cane bagasse, did not show differences in protein patterns, however, the Schiff's staining was more intense in the PN-120 than in the wild strain. These results point out that the mutational treatment did not apparently change the extracellular proteins from mutant PN-120 and this could affect their regulation sites, since derepressed and feed-back resistant enzymes may be produced.

The leaves of the agave plant are left in the field after harvesting the heads for tequila production. Different types of agave leaves were isolated, classified, and their content in the total plant determined. The usable fractions were collected and their properties determined. Of the total wet weight of the agave plant, 54% corresponds to the agave head, 32% corresponds to materials which could be usable for sugar and fiber production which leaves 14% of the wet plant without apparent utility. The fractions with higher total reducing sugars (TRS) content were the fresh fraction of partially dry leaves stuck to the head and the leaf bases with a TRS content of 16.1% and 13.1%, respectively. The highest TRS concentration (16–28%) is in the agave head which is used for tequila production. The leaves are 90–120 cm long and 8–12 cm wide and contain fiber bundles that are 23–52 cm long and 0.6–13 mm wide. The ultimate fiber length is approximately 1.6 mm with an average width of 25 μm. There are several types of leaf fibers that can be utilized depending on what part of the plant they come from and what product is desired. Agave leaf fibers were pulped using a soda pulping process and the pulp was hand formed into test sheets. Test sheets made from pulped agave leaf fibers had a breaking length comparable to paper made from both pine and eucalyptus fibers, but the tear index and burst index were lower than the other two papers.

Treatment of the paper factory effluent was done with free and immobilized cells of a phenol degrading Alcaligenes sp. d 2 . The free cells could bring a maximum of 99% reduction in phenol and 40% reduction in chemical oxygen demand (COD) after 32 and 20 h of treatment, respectively. In the case of immobilized cells, a maximum of 99% phenol reduction and 70% COD reduction was attained after 20 h of treatment under batch process. In the continuous mode of operation using packed bed reactor, the strain was able to give 99% phenol removal and 92% COD reduction in 8 h of residence time The optimum flow rate was 2.5 ml/h and the half life period was 76 h. Even after the complete removal of phenol, the strain could further enhance reduction in chemical oxygen demand, which clearly indicated that in the paper factory effluent, this strain could also oxidize organic matter other than phenol.

The commercial pre-hydrolysis kraft-based dissolving pulp production process can be a typical example for the demonstration/implementation of the integrated forest biorefinery concept. In this study, the concept of cellulase treatment of this dissolving pulp for enhancement of accessibility/reactivity in terms of viscose rayon production was demonstrated. The cellulase treatment resulted in the formation of additional openings/surface areas in the fiber structure via the possible action of "etching". As a result, the pore volume of pulp fibers increased, which led to the increase in the accessibility to xanthation, and thus Fock reactivity. Results showed that the cellulase treatment was effective in increasing the Fock reactivity, at a cellulase dosage of 2u/g (based on the dry weight of pulp), the Fock reactivity increased from 47.67% to 79.9%. The adoption of cellulase treatment to hardwood kraft-based dissolving pulp can provide an efficient approach for enhancing its performance in the commercial viscose-rayon process.

The mechanism of the increase in the hydrolysis rate and yield by the addition of Tween 80 to the hydrolysis reaction of filter paper was investigated under static and agitated conditions. The increase in the hydrolysis rate by addition of Tween 80 was observed under the agitated condition only. The effects of Tween 80 on the changes in the protein concentration of individual cellulase components were investigated in the absence of substrates. Agitation of the enzyme solution resulted in the drastic decrease of SDS-PAGE bands intensity of CBH2 (cellobiohydrolase 2). The addition of Tween 80 prevented this. Thus, the Tween 80 functions to stabilize instable cellulase components under the agitated condition. Moreover, addition of Tween 80 completely suppressed the decrease of CBH2 intensity by agitation at 30°C. Results suggest that Tween 80 stabilizes instable cellulase components not only during hydrolysis, but during enzyme production also.