Assessment of the papermaking potential of processed Miscanthus × giganteus stalks using alkaline pre-treatment and hydrodynamic cavitation for delignification

One way of satisfying increased market demand and simultaneously achieving a reduced environmental load in the industrial paper production is the use of fibrous agricultural residues. The aims of this study were i) to investigate the effect of alkaline - hydrodynamic cavitation (HC) pre-treatments on the delignification of Miscanthus × giganteus stalks (MGS) and ii) establishing the suitability of MGS as feedstock and their exploitation in pulp and paper manufacturing. It was demonstrated that the proposed treatment is an efficient delignification method for the non-wood fiber sources, such as miscanthus. A significant outcome of this work was the observation that HC treatment preserved the fibres lengths and surface quality of raw MGS, but at the same time increased the amount of kinked and curled fibers present in cavitated miscanthus fibers. The average miscanthus fiber length was found to be relatively short at 0.45 (±0.28) mm, while the slenderness ratio, the flexibility coefficient and Runkel ratio values were calculated to be 28.13, 38.16 and 1.62, respectively. The estimated physical properties of MGS pulp hand-sheets were 24.88 (±3.09) N m g^-1 as the tensile index, 0.92 (±0.06) kPa m² g^-1 as the burst index and 4.0 (±0.37) mN m² g^-1 as the tear index. Overall the current work demonstrated effective use of hydrodynamic cavitation for improving the processing in pulp and paper manufacturing.

Statistical Optimization of Alkali Pretreatment to Improve Sugars Recovery from Spent Coffee Grounds and Utilization in Lactic Acid Fermentation

Biorefinery, which utilizes carbon-neutral biomass as a resource, is attracting attention as a significant alternative in a modern society confronted with climate change. In this study, spent coffee grounds (SCGs) were used as the feedstock for lactic acid fermentation. In order to improve sugar conversion, alkali pretreatment was optimized by a statistical method, namely response surface methodology (RSM). The optimum conditions for the alkali pretreatment of SCGs were determined as follows: 75 °C, 3% potassium hydroxide (KOH) and a time of 2.8 h. The optimum conditions for enzymatic hydrolysis of pretreated SCGs were determined as follows: enzyme complex loading of 30-unit cellulase, 15-unit cellobiase and 50-unit mannanase per g biomass and a reaction time of 96 h. SCG hydrolysates were used as the carbon source for Lactobacillus cultivation, and the conversions of lactic acid by L. brevis ATCC 8287 and L. parabuchneri ATCC 49374 were 40.1% and 55.8%, respectively. Finally, the maximum lactic acid production by L. parabuchneri ATCC 49374 was estimated to be 101.2 g based on 1000 g of SCGs through the optimization of alkali pretreatment and enzymatic hydrolysis.

Effects of organic fertilizers via quick artificial decomposition on crop growth

Applying organic matters into the soil would help to improve soil quality and sustain crop production. In addition, the small molecular organic matters could be active in influencing soil nutrient cycling and crop development. Thus, this study has firstly induced a new technology of quick artificial decomposition to produce fertilizers containing small molecular organic compounds from crop residues and other biological wastes. The fertilizers were produced via the quick artificial decomposition from biological wastes. The small organic species in the fertilizers were identified by the LC-MS. Field experiments of kiwifruit were conducted to test the effects of fertilizers. In total, 341 species of small organic matters have been determined in the produced fertilizers. The results showed that the organic fertilizers could significantly increase the yields of kiwifruit by 15.2% in contrast with mineral fertilizer treatments. Whereas, the organic fertilizers could enhance the contents of nutritive components in kiwifruits. These results proved that the organic fertilizers containing more small organic matter could be more efficient in promoting crop production.

Production of nanofibrillated cellulose with superior water redispersibility from lime residues via a chemical-free process

Water removal during drying of nanofibrillated cellulose (NFC) generally results in the formation of hydrogen bonds between fibers, leading to irreversible fiber agglomeration and hence their poor water redispersibility. The feasibility of using lime residues after juice extraction to produce dried NFC possessing superior redispersibility was here investigated. After autoclaving at 110-130 °C for 2 h, high-shear homogenization at 3800 × g for 15 min and high-pressure homogenization at 40 MPa for 5 passes, NFC having the diameters of 5-28 nm and crystallinity index of 44-46% could be obtained. After hot air drying at 60 °C, dried NFC could be well dispersed in water, with viscoelastic property similar to that of the originally prepared NFC suspension. Pectin associated with cellulose nanofibrils helped prevent fiber aggregation during drying and hence facilitating nanofiber redispersion in water. This observed trend was opposite to that belonging to fiber undergone chemical treatments to remove non-cellulosic constituents.