RESUMO
While wet waste hydrothermal liquefaction technology has a high biofuel yield, a significant amount of the carbon and nitrogen in the feedstock reports to the aqueous-phase product. Pretreatment of this stream before sending to a conventional wastewater plant is essential or at the very least, advisable. In this work, techno-economic and life-cycle assessments were conducted for the state-of-technology baseline and four aqueous-phase product treatment and monetization options based on experimental data. These options can cut minimum fuel selling prices by up to 13 % and life-cycle greenhouse gas emissions by up to 39 % compared to the baseline. These findings highlight the substantial influence of aqueous produce treatment strategies on the entire wet waste hydrothermal liquefaction process, demonstrating the potential for optimizing economic viability and environmental impact through further research and development of milder treatment methods and diversified by-product valorization pathways.
Assuntos
Meio Ambiente , Gases de Efeito Estufa , Águas Residuárias , Nitrogênio , Biocombustíveis , BiomassaRESUMO
Biomass was upgraded to fuel blendstocks via catalytic fast pyrolysis (CFP) followed by hydrotreating using three approaches: ex situ CFP with a zeolite catalyst (HZSM-5), ex situ CFP with a hydrodeoxygenation catalyst (Pt/TiO2) and cofed hydrogen, and in situ CFP with a low-cost mixed metal oxide catalyst (red mud). Each approach was evaluated using a common pine feedstock and the same hydrotreating procedure. The oxygen contents in the CFP oils ranged from 17 to 28 wt % on a dry basis, and the carbon efficiencies for the CFP processes were in the range of 28-38%. The residual oxygen was reduced to <1 wt % during hydrotreating, which was operated for 104-140 h for each CFP oil without plugging issues. The hydrotreating carbon efficiencies were 81-93%. The CFP pathway with the hydrodeoxygenation catalyst gave the highest overall carbon efficiency from biomass to fuel blendstocks (34%) but, at the same time, also the highest cumulative hydrogen consumption during CFP and hydrotreating. The zeolite pathway produced the largest fraction boiling in the gasoline range and the highest estimated octane number due to the high aromatic content in that CFP oil. The in situ red mud pathway produced the largest fraction of diesel-range products with the highest derived cetane number. However, advances in the CFP and hydrotreating process are required to improve the fuel blendstock properties for all pathways.
RESUMO
The ability to regulate stem cell proliferation and differentiation has relevance in numerous medical applications, including medical devices, tissue engineering, and regenerative medicine. To control cellular behavior at the biomaterial or scaffold interface, many studies have employed surface modifications that mimic the extracellular matrix. Strikingly absent is the immobilization of cell-surface ligands to the biomaterial surface. One cell-to-cell signaling pathway that has been shown to regulate tissue development and stem cell fate is the Notch pathway. Recently, the Notch signaling pathway was identified as a key regulator of epithelial differentiation. Utilizing this knowledge, we applied an affinity immobilization scheme designed to attach and orient the Notch ligand, Jagged-1, in an active conformation on a biomaterial surface. When epithelial stem cells were plated on the bound ligand, the Notch/CBF-1 signaling pathway was stimulated and the cells upregulated both intermediate- and late-stage differentiation markers. In addition, the ligand promoted tight clustering and extensive stratification. Soluble Jagged-1 showed no Notch/CBF-1 signaling and very little, if any, cell differentiating activity. The high potency of bound Jagged-1 suggests that modification of a surface with a Notch ligand presents a powerful method to control stem cell differentiation at the cell-biomaterial interface.