Energy efficiency challenges in pulp and paper manufacturing: A tutorial review

The pulp and paper industry is highly energy-intensive. In mills that use chemical pulping, roughly half of the higher heating value of the cellulosic material used to manufacture the product typically is incinerated to generate steam and electricity that is needed to run the processes. Additional energy, much of it non-renewable, needs to be purchased. This review considers publications describing steps that pulp and paper facilities can take to operate more efficiently. Savings can be achieved, for instance, by minimizing unnecessary losses in exergy, which can be defined as the energy content relative to a standard ambient condition. Throughout the long series of unit operations comprising the conversion of wood material to sheets of paper, there are large opportunities to more closely approach a hypothetical ideal performance by following established best-practices.

Evaluating the effects of cellulolytic enzymes and Lactobacillus bulgaricus on mycotoxins production and the quality of maize silage

Fungal spoilage and mycotoxin contamination are two of the greatest hazards of silage. The present work was carried out to evaluate the impact of Lactobacillus bulgaricus and cellulolytic enzymes on the maize silage (MS) quality. Fungal analysis of different MS samples showed different mycotoxigenic fungi. The highest frequency (62.8%) was associated with Fusarium spp. Four species with different relative densities were found: F. graminearum (71.1%), F. culmorum (15.2%), F. proliferatum (11.2%), and F. oxysporum (2.50 %). High-performance liquid chromatography analysis showed the presence of trichothecene, nivalenol, zearalenone, and fumonisins mycotoxins in MS inoculated by F. graminearum. The inhibition % of trichothecene, nivalenol, and zearalenone synthesis was 50.2%, 47.5%, and 23.5%, respectively, in MS inoculated by Lactobacillus bulgaricus after a 30 d incubation period. Trichoderma harzianum succeeded in producing cellulolytic enzymes, i.e., carboxymethyl cellulase, manganase peroxidase, and laccase, with a maximum production of 350 µg/mL, 5.47 µg/mL, and 16.0 µg/mL, respectively, after 21 d using MS as the substrate. Treatment by the extracted cellulolytic enzyme with L. bulgaricus enhanced unfavorable conditions for MS fungal contamination, i.e., the production of lactic acid, a lowered pH, and increased L. bulgaricus colony-forming units, compared to the addition of enzyme extract or L. bulgaricus alone.

Energy efficiency challenges in pulp and paper manufacturing: A tutorial review

The pulp and paper industry is highly energy-intensive. In mills that use chemical pulping, roughly half of the higher heating value of the cellulosic material used to manufacture the product typically is incinerated to generate steam and electricity that is needed to run the processes. Additional energy, much of it non-renewable, needs to be purchased. This review considers publications describing steps that pulp and paper facilities can take to operate more efficiently. Savings can be achieved, for instance, by minimizing unnecessary losses in exergy, which can be defined as the energy content relative to a standard ambient condition. Throughout the long series of unit operations comprising the conversion of wood material to sheets of paper, there are large opportunities to more closely approach a hypothetical ideal performance by following established best-practices.

Crystalline structure analysis of all-cellulose nanocomposite films based on corn and wheat straws

Cellulose solution and nanocellulose were prepared from corn straw and wheat straw and then used to fabricate an all-cellulose nanocomposites film (ANF). The crystal structure (CS) of ANFs was analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FTIR). Cellulose-I and cellulose-II were found to coexist within regenerated cellulose films (RCF) and ANFs. With the change of nanocellulose content, the proportions of cellulose-I and cellulose-II changed. Cellulose transformation was found to depend on the raw material and the preparation method. When cellulose solution was prepared from corn straw that had been extracted, the cellulose type tended to be transformed from cellulose-I to cellulose-II; the proportion of cellulose-I showed a tendency to increase when nanocellulose content exceeded 1.5%. When the dissolved cellulose had been treated by an acid-alkali method, the results did not follow a clear pattern. However, when cellulose solution was prepared from wheat straw, under extraction method, the cellulose type tended to transform from cellulose-I to cellulose-II; under acid-alkali method, cellulose-I did not follow a clear pattern with nanocellulose content. Though the small amount of nanocellulose can’t dominate the content of cellulose-I, it could cause an increase in disorder of the cellulose matrix.

Effect of microwave and steam treatment on the thermo-hygro-plasticity of beech wood

The effects of microwave and steam treatment were analyzed relative to the immediate (thermo-hygro-plasticity) and post-assessed (permanent changes) properties of wood. The study was conducted using European beech (Fagus sylvatica L.) standard and 1.5 times up-scaled (only for microwave-heated and reference samples) bending specimens tested in a static three-point loading mode. The specimens were plasticized by heat and moisture (1) separately and (2) simultaneously by heating moist specimens using (i) various microwave regimes in continuous mode, and (ii) heated saturated steam in discontinuous mode. Oven-dried specimens tested at 20 °C served as references. The thermo-hygro-plasticity was studied immediately after treatment, whereas the permanent changes were assessed after oven-drying of plasticized specimens to 0% moisture content. Permanent structural changes were analyzed using scanning electron microscopy. Microwave treatment increased the plasticity of wood (decreasing the modulus of elasticity by 70%) comparably to steam treatment, when the output moisture content was 30% or higher. A similar degree of plasticity was found in up-scaled specimens heated by microwaves. Further analyses confirmed that microwave treatment did not cause any permanent damage to wood structure or reduce mechanical performance. The results showed that microwave treatment is an efficient alternative to steaming when plasticizing moist wood.

Predicting mechanical properties of clear wood from Acacia mangium provenances using ultrasound

Ultrasound was considered as a means for determining mechanical properties of clear wood in six different Acacia mangium provenances from a trial forest planted in Vietnam. A total of 30 trees (5 trees from each provenance) with no major defects were selected, and a 50-cm-long log was obtained at 1.3 m above the ground from each tree for the assessment of mechanical properties. The measured average ultrasound velocities for provenances tested in the longitudinal direction ranged from 4094 m/s to 4271 m/s. The predicted average dynamic modulus of elasticity (Ed) values varied from 7.42 GPa to 8.70 GPa among provenances. The Ed indicated significant positive correlation coefficients with modulus of elasticity (0.64 to 0.96), modulus of rupture (0.44 to 0.87), and compression strength (0.54 to 0.92) for provenances examined in this study. The results indicated that the use of ultrasound was feasible to determine the mechanical properties of A. mangium provenances planted in Vietnam.

Physical-mechanical properties and durability enhancement of glued laminated lumber made from inner part of Gewang (Corypha utan Lam.) trunk: The effect of lamina densification and lumber smoking

The inner part of gewang (Corypha utan Lam.) trunk has significantly lower physical-mechanical properties as well as biodeterioration resistance, compared to outer parts. This study investigated a method for improving the physical-mechanical properties and biodeterioration resistance of glued laminated lumber made from the inner part of gewang trunk (GLIT). The effects of pretreating the lamina with densification and exposing the GLIT to smoking process were investigated. The seven layers of GLIT samples were bonded with isocyanate adhesive at a glue spread of 280 g/m2, then smoked for 15 days. Solid lumber pieces made from the inner part as well as the outer part of GLIT were also prepared for comparative purposes. Physical and mechanical properties of the lumber samples were tested according to Japanese agricultural standards. Meanwhile, dry-wood termite and wood decaying fungi resistances of the lumber samples were determined according to Indonesian standard. Results showed that overall physical-mechanical properties as well as dry-wood termite and decay resistances of densified-smoked GLIT were enhanced significantly. Pretreating of lamina and post-production smoking can be considered as a potential method to improve physical-mechanical properties and biodeterioration resistance of the GLIT.

Readiness for and adoption of Industry 4.0 among small and medium sized enterprises in the Malaysian furniture industry

The furniture industry is the fastest growing sub-sector in the Malaysian wood-based industry. Although it has grown tremendously over the years, it is characterized by stagnating value-addition. To improve industrial competitiveness, automation and technology application has emerged as a possible solution. A study was conducted to evaluate the influence of company size towards their readiness and adoptability of automation and Industry 4.0. A questionnaire-based survey involving large-, medium-, small-, and micro-sized furniture manufacturers throughout Malaysia was conducted with 160 respondents. The analysis of the results from the survey showed that there was a significant relationship between company size and their readiness for Industry 4.0. The results showed that small- and medium-sized enterprises (SMEs) are more hesitant in adopting technology due to the high cost required and the lack of skilled workers to cope with the new technology, compared to the large sized companies. The factor analysis revealed that the three main groups of the factor affecting decisions towards adopting industry 4.0 are government policy, difficulty in implementation, and expected benefit. This study suggests that providing incentives for the application of automation and technology will be required when the goal is greater uptake of technology among furniture manufacturers.

Dynamic testing of the elastic modulus and shear modulus of full-scale laminated veneer lumber

The feasibility of the dynamic testing was explored for the elastic modulus and shear modulus of full-scale laminated veneer lumber in batches at the production site. In order to do so, dynamic testing and analysis, involving a hammer blow and detection of frequencies, were carried out on the laminated veneer lumber free-plate placed in two ways: suspended and placed on a sponge. The results showed that the mode shape and modal frequency value of the suspended laminated veneer lumber free-plate obtained from the modal test were consistent with those of the specimens placed on the sponge. The elastic modulus and shear modulus values of the laminated veneer lumber free-plate obtained in sponge mode based on the transient excitation method were 3.99% and 3.08% higher than the elastic modulus and shear modulus values of the laminated veneer lumber obtained in suspension mode obtained based on the modal test method. The feasibility and reliability of the elastic modulus and shear modulus values obtained by the laminated veneer lumber free-plate in sponge mode were verified.

Wood fiber-reinforced polylactic acid sheets enabled by papermaking

Polylactic acid is a biodegradable thermoplastic polyester derived from renewable polysaccharides. In this work, softwood fibers were used to reinforce the paper sheet made from polylactic acid fibers, thus addressing the challenges regarding low density, rough surface, and weak strength. The impact of wood fibers and calendering on the physical properties (density, roughness, tensile strength, and folding endurance) of the composite paper were identified. Furthermore, the morphology of papers with different fiber contents and those that had been calendered was characterized with a scanning electron microscope. The use of wood fibers resulted in the improvement of the physical properties of the polylactic acid paper, and the enhanced refining of wood fibers had a favorable role in improving paper density, smoothness, and mechanical strength. The tensile index increased 37.9% when the beating degree of wood fibers increased from 25 to 60 °SR. After calendering, the density, smoothness, tensile strength, folding endurance, and air barrier property of the paper were improved 60.2%, 45.8%, 15.5%, 148.1%, and 79.4%, respectively. The calendering-based papermaking process involving the combined use of wood fibers and polylactic acid fibers would be a promising strategy for designing composite materials for tailorable end-uses.