Guía para prácticas de Aspen Plus 7.2 en Operaciones de Separación G-L y L-L CURSO 2012-2013

Guía descriptiva de introducción al uso del simulador de procesos ASPEN PLUS en su versión 7.2 al dimensionamiento, resolución y diseño de unidades de separación en operaciones gas-líquido y líquido-líquido.56 página

Yield evaluation of enzyme hydrolysis and dark fermentation of the brown seaweed Rugulopteryx okamurae hydrothermally pretreated by microwave irradiation

Microwave irradiation has been applied to solubilise the organic matter from the invasive seaweed Rugulopterix okamurae as pretreatment for two conventional biological processes: enzyme hydrolysis (EH) for obtaining reducing sugars (RS) and dark fermentation (DF) for obtaining volatile fatty acids (VFAs). As operational conditions for the microwave pretreatment, temperature and time has been tested between 120 and 220 °C and 5–20 min respectively. The maximum solubilisation yield in terms of DOC (26%) through the microwave pretreatment was registered at 220 °C at 20 min. However, the maximum concentration for RS (1.8 g/L) was obtained at 200 °C at 20 min due to the decomposition of monomeric sugars at high temperature and the total polyphenols (TP) were above 0.25 g/L (where inhibition in dark fermentation begins to be noticiable) at 180 °C. When the pretreated biomass was used for the EH the maximum accumulated RS production was 160 mg-RS/g-biomass, at 220 °C which was a 35% better than the RS production for non-pretreated biomass. In the case of the DF tests, the maximum yield of VFAs obtained with the pretreated biomass was 46.3 mg/g-biomass at 220 °C while the maximum hydrogen yield was obtained at 200 °C (6.6 mL-H2/g-biomass) due to the high level of TP (1.1 g/L) of pretreated biomass at 220 °C. Despite of this toxic effect, the VFAs production at 220 °C was 93% higher than in the non-pretreated biomass

Effect of passively aerated biological pretreatment on different biomasses with diverse lignocellulosic fiber profiles

Passively aerated biological pretreatment was applied to four different lignocellulosic biomasses with varying fiber content profiles: sugar beet pulp (SBP), brewery bagasse (BB), rice husk (RH), and orange peel (OP). In order to analyze the organic matter solubilization yield at 24 and 48 h, different percentages of activated sewage sludge (2.5–10%) were utilized as inoculum. The OP achieved the best organic matter solubilization yield in terms of soluble chemical oxygen demand (sCOD) and dissolved organic carbon (DOC) at 2.5% inoculation and 24 h: 58.6% and 20%, respectively, since some total reducing sugars (TRS) consumption was identified after 24 h. On the contrary, the worst organic matter solubilization yield was obtained with RH, the substrate with the highest lignin content among the tested, with percentages of 3.6% and 0.7% in terms of sCOD and DOC respectively. In fact, it could be considered that this pretreatment was not successful with RH. The optimum inoculation proportion was 7.5% (v/v) except for the OP (2.5% (v/v)). Finally, due to the counterproductive organic matter consumption at longer pretreatment durations, the optimal time for BB, SBP, and OP was 24 h

Production of Free Sugars by Enzymatic Hydrolysis of Dictyota dichotoma

It is well-known that brown macroalgae can be used as a source of valuable sugars with different biological activities, but its polymeric macrostructures should be hydrolyzed for obtaining an acceptable yield. This study deals with the production of free sugars by the enzymatic hydrolysis of optimized biologically pretreated brown seaweed. The biological pretreatment was carried out using solid-state fermentation (SSF) with a white root fungus species (Aspergillus awamori). For this purpose, different temperature growth conditions (30ºC and 50ºC) and inoculum concentrations (106; 107 and 108 spores/g of dried solid) were tested for 20 days of the SSF process. In addition, different dosages of commercial hydrolytic enzyme cocktail Cellic® Ctec2 were tested for enzymatic hydrolysis (EH) of D. dichotoma at a solid/liquid ratio of 2.2% w/v. Finally, biologically pretreated samples at optimum conditions (30ºC and inoculum size of 108 cel/mL) were hydrolyzed with commercial Cellic®Ctec2 at the optimum dosage (112FPU/g). The maximum reducing sugars concentration measured in the hydrolysates was 80 g/kg biomass. Further investigations increasing the solid-liquid ratio and reducing the enzyme dosage are necessary for the complete optimization of sugar production from D. dichotoma

Editorial of the special issue “Anaerobic co-digestion of lignocellulosic wastes”

Editorial from the special issue Anaerobic Co-Digestion of Lignocellulosic Wast

Successful and stable operation of anaerobic thermophilic co-digestion of sun-dried sugar beet pulp and cow manure under short hydraulic retention time.

This work consists of a long-term (621 days) experimental study about biogas production from sun dried sugar beet pulp and cow manure. Thermophilic (55°C) anaerobic co-digestion was performed in semi-continuous reactors, testing ten hydraulic retention times (30-3 days) (HRTs) and organic loading rates (2-24 gVS/Lreactor∙d) (OLRs). Results showed that the best global system performance (regarding stability, biogas production, and organic matter removal) was achieved at an HRT as short as 5 days (OLR of 12.47 gVS/Lreactor∙d) with a biogas yield of 315 mL/gVSadded. The gradual OLR increase allowed system control and time-appropriate intervention, avoiding irreversible process disturbances and maintaining admissible acidity/alkalinity ratios (<0.8) for HRTs ranging from 30 to 4 days. The accumulation of acetic acid was the main cause of the process disturbance observed at short HRTs. It was deduced that for the HRT of 3 days, the methane productivity was mainly owing to the hydrogen-utilizing methanogens pathway. This research clearly shows how an adequate combination of agro-industrial wastes and livestock manure could be processed by anaerobic co-digestion in short HRTs with great efficiency and stability and deepens in the understanding of the start-up, stability and optimization of the co-digestion

Insights into Anaerobic Co-Digestion of Lignocellulosic Biomass (Sugar Beet By-Products) and Animal Manure in Long-Term Semi-Continuous Assays

Biogas production through anaerobic digestion has proven to be one of the most important pillars of the transition into the circular economy concept, a sustainable approach for biorefinery. This work aims to extend and improve knowledge in the anaerobic co-digestion of complementary substrates, given insights into wastes biodegradability and the influence of manure composition on the anaerobic process stability. Anaerobic co-digestion of sugar beet by-products with two kinds of animal manure (pig and cow) was investigated in semi-continuous assays, analyzing both common and non-classical parameters. Co-digestion with manure clearly mitigated the inhibitory effect of volatile fatty acids at high organic loading rates, leading to increases in methane production by 70% and 31% in comparison with individual digestion of sugar beet by-products, for co-digestion with pig and cow manure, respectively. Non-classical parameters could give more insight into the coupling/uncoupling of the anaerobic digestion phases and the involved microorganisms. Indirect parameters indicated that the process failure at the critical organic loading rates was mainly due to methanogenesis inhibition in the co-digestion with pig manure, while in co-digestion with cow manure or in individual digestion of sugar beet by-products, both hydrolysis-acidogenesis and methanogenesis phases were affected. Biomethanation degree refers to the maximum methane potential of organic wastes. Sugar beet by-products required a long digestion-time to reach high biodegradability. However, short digestion-times for co-digestion assays led to a high biomethanation degree

Effect of Temperature on Biohydrogen and Biomethane Productions by Anaerobic Digestion of Sugar Beet by-Products

This work analyzes the effect of temperature on the anaerobic digestion of sugar beet by-products for both biohydrogen and biomethane production. The findings demonstrate that the anaerobic process was significantly affected by the increase in temperature from mesophilic to thermophilic or hyper-thermophilic conditions. Therefore, it was found that the mesophilic temperature was more suitable for the anaerobic digestion of sugar beet by-products, using either the raw feedstock or the pretreated feedstock at higher temperatures. The specific production of biohydrogen from thermophilic acidogenic digester was 1.7 fold higher than that obtained from the hyper-thermophilic one. Moreover, when raw feedstock was used in single stage digesters, a methane production rate of 0.55 LCH4/Lr*d was obtained from the mesophilic digester, which was 45% higher than that of the thermophilic one. It has been observed that the increase in temperature led to a high accumulation of volatile and long chain fatty acids, inhibiting and slowing down the anaerobic process

Pre-composting of municipal solid wastes as enhancer of bio-hydrogen production through dark fermentation process

This study was focused on bio-hydrogen production from thermophilic dry anaerobic acidogenic co-digestion (55 °C and 20 % of total solids) of pre-composted mixtures of organic fraction of municipal solid waste (OFMSW) and food waste (FW). Three different mixture ratios of OFMSW:FW (80:20, 70:30 and 50:50) have been tested. The application of pre-composting improved the hydrolytic and acidogenic phases in the subsequent acidogenic co-digestion, reaching an increase in the bio-hydrogen production in the range of 45.4–46.7 %. In this sense, the best results were obtained for the pretreated mixture with the ratio 70:30, with 42.9 LH2/kg VSadded and 53.9 % of H2 in the biogas. Finally, the kinetic study has corroborated that pre-composting clearly enhances the kinetics of acidogenic fermentation of OFMSW and FW mixtures. In fact, the μmax and YP values for the pretreated mixtures have been increased by a 20 % and 33 % respectively

Valorisation of the invasive alga Rugulopteryx okamurae through the production of monomeric sugars.

Rugulopteryx okamurae is an invasive brown alga causing severe environmental and economic problems on the western Mediterranean coasts. Thus, in addition to the difficulties caused to the fishing and tourism sectors, there is a need to manage its accumulation on the beaches. This work aims to valorise this waste by using it as raw material for producing monosaccharides through a two-stage sequential process. These sugars could be used for different fermentative processes to obtain high-value-added bioproducts. In this work, biological pretreatment of the previously conditioned seaweed with the fungus Aspergillus awamori in solid-state fermentation (SSF), followed by enzymatic hydrolysis with a commercial enzyme cocktail, was performed. The effect of the extension of the biological pretreatment (2, 5, 8 and 12 days) on the subsequent release of total reducing sugars (TRS) in the enzymatic hydrolysis stage was studied. To analyse this effect, experimental data of TRS produced along the hydrolysis were fitted to simple first-order kinetics. Also, the secretion of cellulase and alginate lyase by the fungus, along with the biological pretreatment, was determined. The results suggest that 5 days of biological pretreatment of the macroalgae with A. awamori followed by enzymatic saccharification for 24 h with Cellic CTec2 (112 FP units/g of dry biomass) are the best conditions tested, allowing the production of around 240 g of TRS per kg of dried biomass. The main sugars obtained were glucose (95.8 %) and mannitol (1.5 %), followed by galactose (1 %), arabinose (0.9 %) and fucose (0.5 %). KEY POINTS: Five-day SSF by A. awamori was the best condition to pretreat R. okamurae. Five-day SSF was optimal for alginate lyase production (1.63 ±0.011 IU/g biomass). A maximum yield of 239 mg TRS/g biomass was obtained (with 95.8 % glucose)