Life cycle assessment of lignocellulosic biomass pretreatment methods in biofuel production

Purpose: In converting lignocellulosic biomass into biofuel, a pretreatment stage is required in order to make the biomass more readily available for the transformation. There are numerous pretreatment techniques that can be chosen, which are broken down into four categories: chemical, physical, physicochemical, and biological. The aim of this work is to provide a new assessment for some of the emerging technologies using life cycle assessment (LCA) combined with an analysis of the overall product yield. Methods: Using literature data, an LCA of four different pretreatment methods was carried out. Liquid hot water (LHW), steam explosion (SE), dilute acid (DA), and organosolv (OS) were chosen as the most common techniques with high scalability potential. Models were constructed using GaBi software. A cradle-to-gate analysis was selected with a common model of the corn stover growth and harvesting cycle being combined with the individual models for each pretreatment. Four impact categories were analyzed, and a selection has been discussed based on relevance to the biofuel production process. Results and discussion: In nearly all of the impact categories, DA performs the worst due to the length of the process (12 h) and the amount of electricity required to elevate the temperature to 60 °C for that time period. In many of the other categories, the remaining three pretreatments perform comparably to each other with the exception of LHW which has significantly reduced CO2 emissions. LHW has slightly higher water depletion rates than both SE and OS, which is to be expected given the nature of the process. In terms of product yield, LHW produced twice as much total sugar than any of the other processes. Conclusions: The project concluded that while LHW and SE are viable options for the pretreatment of biomass, LHW is the most suitable technique for the pretreatment of corn stover. This pretreatment was environmentally friendly as it produced the lowest CO2 emissions, aligning with the main objective behind developing biofuels from agricultural residues. The process was also technically the most effective as it resulted in the highest sugar yields. Methods: Using literature data, an LCA of four different pretreatment methods was carried out. Liquid hot water (LHW), steam explosion (SE), dilute acid (DA), and organosolv (OS) were chosen as the most common techniques with high scalability potential. Models were constructed using GaBi software. A cradle-to-gate analysis was selected with a common model of the corn stover growth and harvesting cycle being combined with the individual models for each pretreatment. Four impact categories were analyzed, and a selection has been discussed based on relevance to the biofuel production process. Results and discussion: In nearly all of the impact categories, DA performs the worst due to the length of the process (12 h) and the amount of electricity required to elevate the temperature to 60 °C for that time period. In many of the other categories, the remaining three pretreatments perform comparably to each other with the exception of LHW which has significantly reduced CO2 emissions. LHW has slightly higher water depletion rates than both SE and OS, which is to be expected given the nature of the process. In terms of product yield, LHW produced twice as much total sugar than any of the other processes. Conclusions: The project concluded that while LHWand SE are viable options for the pretreatment of biomass, LHWis the most suitable technique for the pretreatment of corn stover. This pretreatment was environmentally friendly as it produced the lowest CO2 emissions, aligning with the main objective behind developing biofuels from agricultural residues. The process was also technically the most effective as it resulted in the highest sugar yields

Biodegradation as natural fibre pre-treatment in composite manufacturing

Bacterial and fungal degradation of wheat straw has become intensively scrutinised in recent years because of the growing interest in procuring useful feedstocks and chemicals from lignocellulosic sources. Typically, after the extraction of valuable sugars and phenolics, significant quantities of solid biomass remain as waste. In this work, it has been shown that the leftover fermented wheat straw can be successfully used to reinforce epoxy resins, providing better strength properties compared to non-degraded straw. A 12% and a 22% increase in Young’s modulus and ultimate tensile strength respectively were observed for degraded wheat straw/epoxy composites compared to composites containing non-degraded straw. The improvement in mechanical strength is explained in terms of the structural and morphological transformations that occurred in the fibres during the fermentation process. The opportunity to use degraded natural fibres in the manufacturing of composites, in addition to the production of chemicals from lignocellulosic feedstocks, looks promising for improving biorefinery economics further

Phytoremediation combined with biorefinery on the example of two agricultural crops grown on Ni soil and degraded by P. chrysosporium

During the last few decades, phytoremediation process has attracted much attention because of the growing concerns about the deteriorating quality of soil caused by anthropogenic activities. Here, a tandem phytoremediation/biorefinery process was proposed as a way to turn phytoremediation into a viable commercial method by producing valuable chemicals in addition to cleaned soil. Two agricultural plants (Sinapis alba and Helianthus annuus) were grown in moderately contaminated soil with ca. 100 ppm of Ni and further degraded by a fungal lignin degrader - Phanerochaete chrysosporium. Several parameters have been studied: the viability of plants, biomass yield and their accumulating and remediating potentials. Further down-stream processing showed that up to 80% of Ni can be easily extracted from contaminated biomass by aqueous extraction at mild conditions. Finally, it was demonstrated that the grown onto contaminated soil plants can be degraded by Phanerochaete chrysosporium and the effect of nickel and biomass pre-treatment on the solid state fermentation was studied. The proposed and studied in this work methodology can pave the way to successful commercialization of the phytoremediation process in the near futur

Preparation of printable and biodegradable cellulose-laponite composite for electronic device application

Printable and biodegradable printed circuit boards (PCBs) prepared by using cellulose as the continuous matrix, laponite as flame retardant filler with various weight ratio (0, 5, 10 and 20 wt% with respect to the α-cellulose quantity used to prepare the composites) and 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) as the recoverable dissolution medium. Prepared cellulose-composites were subjected into physical, chemical, thermal, mechanical and biodegradation analyses to check the suitability of the cellulose-laponite composite for biodegradable electronic application. The addition of laponite into cellulose increased the degradation temperature, flame retardancy and decreased the mechanical properties of the cellulose-laponite composites. The surface nature of the cellulose composite converted from hydrophilic to hydrophobic (contact angle value increased in the range from 50° to 112°) by treating with relatively small amount of hydrophobizing agent (< 1 wt%). The conductive ink printing experiments on the composites explaining the role of hydrophobizing agent and laponite in the composites. Biodegradability of the cellulose was evaluated by enzyme treatments and derived the effect of laponite, hydrophobic agent and conductive ink

A radiofrequency heated reactor system for post-combustion carbon capture

Several problems with stabilization of electricity grid system are related to the time lag between the electricity supply and demand of the end users. Many power plants run for a limited period of time to compensate for increased electricity demand during peak hours. The amount of CO2 generated by these power installations can be substantially reduced via the development of new demand side management strategies utilizing CO2 absorption units with a short start-up time. The sorbent can be discharged using radiofrequency (RF) heating to fill the night-time valley in electricity demand helping in the stabilization of electricity grid. Herein a concept of RF heated fixed bed reactor has been demonstrated to remove CO2 from a flue gas using a CaCO3 sorbent. A very stable and reproducible operation has been observed over twenty absorption-desorption cycles. The application of RF heating significantly reduced the transition time required for temperature excursions between the absorption and desorption cycles. The effect of flow reversal during desorption on desorption time has been investigated. The desorption time was reduced by 1.5 times in the revered flow mode and the total duration of a single absorption-desorption cycle was reduced by 20%. A reactor model describing the reduced desorption time has been developed

Bicatalytic conversion of glycerol to value-added products

The objective of this study was to develop a tandem bio- chemical transformation of a feedstock material to value-added products. The chosen example is microbial fermentation of glycerol with subsequent esterification of the intermediate 1,3-propanediol with fatty acids. The use of biphasic aqueous/organic medium for the bi-catalytic system is the key feature of this study. In the first part of this work, batch and continuous fermentations of glycerol by Clostridium Butyricum bacteria were optimized to increase productivity of 1,3-propanediol. In the second part, several catalysts were screened for mono- and biphasic transformation of 1,3- propanediol. It was discovered that enzymes are the most suitable catalysts for the tandem reactions of glycerol to 1,3-propanediol derivatives compared to chemical catalysts. Biphasic enzymatic esterification of 1,3-propanediol was further optimized using Rhizomucor miehei lipase. Finally, a segmented flow tubular reactor and hollow fiber membrane contactors were designed and tested as a concept tandem reactor. The hollow fiber reactor with Rhizomucor miehei lipase immobilized onto polypropylene membrane was found to be the most effective in the biphasic linoleic acid/aqueous esterification of 1,3-propanediol. In general, the demonstrated approach and the developed system can be easily utilized in the biorefinery processes to avoid extraction and purification of the intermediate products, thus reducing time, energy and emissions

Bicatalytic conversion of glycerol to value-added products

The objective of this study was to develop a tandem bio- chemical transformation of a feedstock material to value-added products. The chosen example is microbial fermentation of glycerol with subsequent esterification of the intermediate 1,3-propanediol with fatty acids. The use of biphasic aqueous/organic medium for the bi-catalytic system is the key feature of this study. In the first part of this work, batch and continuous fermentations of glycerol by Clostridium Butyricum bacteria were optimized to increase productivity of 1,3-propanediol. In the second part, several catalysts were screened for mono- and biphasic transformation of 1,3- propanediol. It was discovered that enzymes are the most suitable catalysts for the tandem reactions of glycerol to 1,3-propanediol derivatives compared to chemical catalysts. Biphasic enzymatic esterification of 1,3-propanediol was further optimized using Rhizomucor miehei lipase. Finally, a segmented flow tubular reactor and hollow fiber membrane contactors were designed and tested as a concept tandem reactor. The hollow fiber reactor with Rhizomucor miehei lipase immobilized onto polypropylene membrane was found to be the most effective in the biphasic linoleic acid/aqueous esterification of 1,3-propanediol. In general, the demonstrated approach and the developed system can be easily utilized in the biorefinery processes to avoid extraction and purification of the intermediate products, thus reducing time, energy and emissions.EThOS - Electronic Theses Online ServiceGBUnited Kingdo