Sustainability assessment of xylitol production from empty fruit bunch

Empty fruit bunch (EFB), one of the wastes from palm oil production, can be utilized into fuels and chemicals. The aim of this paper is to find the optimum capacity to produce xylitol from EFB. The optimum capacity was found by simultaneously considering its profitability, hazard potential and environmental performances. The process was developed and simulated using Aspen Plus to analyze its technical challenges and economic performances, covering net present values, internal rate of returns and payback period. On the other hand, hazard identification and ranking (HIRA) was used to evaluate its safety performances, while Simapro V.8.5.2 was used to assess the environmental impact via a life cycle assessment (LCA). The results show that the high consumption of steam in chemical hydrogenation causes the main contribution of Global warming potential (GWP) by 62%. This acid pre-treatment is also considered the most toxic part of the process while the hydrogenation of xylitol is the most hazardous part based on fire and explosion perspectives. Then, multi-objective optimization using Genetic Algorithm (GA) was performed in Matlab to find the optimum capacity. The methodology and result of this work lay the foundation of future works in utilizing

Sustainability assessment of xylitol production from empty fruit bunch

Empty fruit bunch (EFB), one of the wastes from palm oil production, can be utilized into fuels and chemicals. The aim of this paper is to find the optimum capacity to produce xylitol from EFB. The optimum capacity was found by simultaneously considering its profitability, hazard potential and environmental performances. The process was developed and simulated using Aspen Plus to analyze its technical challenges and economic performances, covering net present values, internal rate of returns and payback period. On the other hand, hazard identification and ranking (HIRA) was used to evaluate its safety performances, while Simapro V.8.5.2 was used to assess the environmental impact via a life cycle assessment (LCA). The results show that the high consumption of steam in chemical hydrogenation causes the main contribution of Global warming potential (GWP) by 62%. This acid pre-treatment is also considered the most toxic part of the process while the hydrogenation of xylitol is the most hazardous part based on fire and explosion perspectives. Then, multi-objective optimization using Genetic Algorithm (GA) was performed in Matlab to find the optimum capacity. The methodology and result of this work lay the foundation of future works in utilizing

Finned spacer for efficient membrane fouling control in produced water filtration

© 2019 Elsevier Ltd Membrane based technologies are highly reliable for water and wastewater treatment, including for removal of total oil and grease from produced water. However, performances of the pressure driven processes are highly restricted by membrane fouling and the application of traditional air bubbling system is limited by their low shear stress due to poor contacts with the membrane surface. This study develops and assesses a novel finned spacer, placed in between vertical panel, for membrane fouling control in submerged plate-and-frame module system for real produced water filtration. Results show that permeability of the panel is enhanced by 87% from 201 to 381 L/(m2 h bar). The spacer system can be operated in switching mode to accommodate two-sided panel aeration. This leads to panel permeability increment by 22% higher than the conventional vertical system. The mechanisms of finned spacer in encouraging the flow trajectory was proven by visual observation and flow simulation. The fins alter the air bubbles flow trajectory toward the membrane surface to effectively scour-off the foulant. Overall results demonstrate the efficacy of the developed spacer in projecting the air bubble trajectory toward the membrane surface and thus significantly enhances membrane panel productivity

Effect of membrane properties on tilted panel performance of microalgae biomass filtration for biofuel feedstock

© 2019 Elsevier Ltd Efficient membrane-based technology for microalgae harvesting can be achieved via application effective membrane fouling control coupled with appropriate membrane materials. This study explores the combined impact of membrane properties and the tilted panel system on filterability of Euglena sp broth, a potential source of biofuel feedstock. Four membranes from polyvinylidene difluoride (PVDF) and polysulfone (PSF) of PVDF-1, PVDF-3, PSF-1 and PSF-3 were evaluated. Generally, increasing aeration rate, tilting angle and lowering switching period enhance the system performance for all the tested membranes to give the highest permeances of 660, 724, 743 L/m2 h bar, respectively. Those values are among the highest reported in literature. The magnitude of the effect is affected by the membrane properties, mainly by pore size. Tilting without switching configuration is desirable for the membrane with a large pore size (PVDF-1, 0.42 μm) which produced the highest panel permeability of 724.3 (L/m2 h bar), which is >23% higher than the tilted with switching. For this membrane, intermittent aeration applied under switching mode worsened the pore blocking. Membranes with low pore sizes (0.11, 0.04 and 0.03 μm for PVDF-3, PSF-1 and PSF-3, respectively) excelled under switching mode since they are less prone to pore blocking due to smaller pore apertures. Overall results suggest that to gain the full benefit of the tilted panel, operational system of either one-sided without switching or two-sided involving switching must be tailored in conjunction with the desirable properties of the membranes. This finding can help to lower the energy input for microalgae-based biofuel production

Using amino-nitrogen pools and fluxes to identify contributions of understory Acacia

Amino acid concentration and composition in xylem and phloem sap and in plant tissues are good markers of plant performance and general plant nitrogen (N)-supply. Here, we tested if amino acid pools in Eucalyptus regnans, growing in southeastern Australia were increased by understory acacias in 70-yr-old stands, and if xylem N-transport of temperate Acacia spp. differs from their tropical counterparts. We analysed amino-N concentrations and composition in foliage, xylem and phloem. In a novel approach we coupled amino-N concentrations of xylem with long-term sap flow measurements to calculate total stand N-transport. Xylem N-transport of E. regnans is largely based on amino compounds of the glutamate group (more than 90%). By contrast, Acacia spp. transport mainly aspartate group amino acids in xylem (up to 80%). Amino compound diversity and concentration in tissues and xylem and phloem sap were universally greater in acacias compared to eucalypts. Acacias investigated here can be classified as 'amide transporters'. We conclude that N-status and growth potential of aging E. regnans forest is not enhanced by a contribution of N from understory acacias, and that xylem N-transport in temperate Acacia spp. differs from acacias located in the tropics