Multiple Value-added Products Research Articles

An integrated valorization of industrial waste of eggplant: Simultaneous recovery of pectin, phenolics and sequential production of pullulan

Based on a bio-refinery concept, the valorization of eggplant peel wastes (EPW) in the production of multiple value-added products was aimed. The acid-free extraction process was applied in the simultaneous recovery of pectin and phenolic compounds. The extraction variables were optimized by response surface methodology using a Box-Behnken design and the maximum yield of pectin (26.1%) and phenolic compounds (20.2%) was obtained in the extraction temperature of 90 °C, time of 90 min and liquid/solid ratio of 40 mL/g. After recovery of pectin and phenolic compounds from EPW, the solid leftovers were enzymatic hydrolyzed and the hydrolysates were used as a carbon source in the microbial production of pullulan by Aureobasidium pullulans. The produced pectin and pullulan were characterized through the chemical and structural features. The results of FT-IR and H-NMR analysis approved the predominant presence of these two polysaccharides in the isolated samples. On the other hand, the antioxidant activity of the recovered phenolic compounds extract was evaluated by DPPH and ABTS radical scavenging activity and reducing power assay.

Facile and cost-efficient indirect carbonation of blast furnace slag with multiple high value-added products through a completely wet process

Mineral carbonation of blast furnace slag (BFS) has been proposed as a comprehensive method for carbon capture and storage and utilization of the industrial solid waste. However, the challenge for this technology to be applied practically is how to reduce the cost of process. A completely wet process combining a CO2-mineralization cell for CO2 capture and membrane electrolysis for recovery of carbonated mother liquor is proposed to simultaneously fix CO2 and produce multiple value-added products. In this process, Ca, Mg, Al, and Si are extracted from BFS with an NH4HSO4 solution prepared from H2SO4 and (NH4)2SO4 with extraction ratios of 97.3%, 98.8%, 96.4%, and 94.3% under optimized conditions, respectively. The extracted Al and Si are then recovered as NH4Al(SO4)2·12H2O (99.59 wt%) and SiO2 (97.70 wt%) with 93% and 98.1% yield, respectively. The CaSO4-rich leaching residue and MgSO4-rich leachate after complete depletion of the residual Al and Si are successively carbonated with an NH4HCO3 solution obtained from a CO2-mineralization cell with total CO2 capacity up to 361 kg-CO2 per tonne BFS. The preliminary economic evaluation shows that the present carbonation route is a cost-efficient method to comprehensively utilize BFS and reduce CO2 emissions.

Economic analysis of forest management alternatives: Compositional objectives, rotation ages, and harvest methods in boreal forests

Timber production and economic gain are important forestry objectives. Boreal forests have long been an important contributor to commodity products. However, in recent decades, commercial production in the boreal forest industry is undergoing a fundamental shift from traditional wood products to multiple value-added products including residues for bioenergy production. In order to help decision makers select economically optimal forest management alternatives, we conducted an empirical study, the first of its kind, to explore the impact of varying silvicultural intensities, forest compositions, rotation ages, and harvest methods on profits in a portion of boreal forest in Northwestern Ontario. We found that silvicultural intensity, forest composition, rotation age, and harvest method significantly affected profit. The profit was on average the highest from coniferous stands, followed by mixedwood and broadleaved compositions. The profits in mixedwood stands increased continuously with rotation age using both Full-Tree to Roadside Tree-Length-to-Mill harvesting method (FT-TL) and Full-Tree to Roadside Shortwood-to-Mill method (FT-SW), and increased with rotation age but decreased at late-succession stage using Cut-to-Length method (CTL). The profits were on average higher using FT-TL than using FT-SW and CTL. The maximum profit ($3305/ha) was solved for low silvicultural intensity (conifer – conifer), with a rotation age of 100years, using the FT-TL harvest method. This analysis provides an example of finding economically optimal forest management solutions.