Biochemical Conversion Research Articles

Floating Aquatic Macrophytes in Wastewater Treatment: Toward a Circular Economy

Floating aquatic macrophytes have a high level of proficiency in the removal of various contaminants, particularly nutrients, from wastewater. Due to their rapid growth rates, it is imperative to ensure the safe removal of the final biomass from the system. The ultimate macrophyte biomass is composed of lignocellulose and has enhanced nutritional and energy properties. Consequently, it can serve as a viable source material for applications such as the production of bioenergy, fertilizer and animal feed. However, its use remains limited, and in-depth studies are scarce. Here, we provide a comprehensive analysis of floating aquatic macrophytes and their efficacy in the elimination of heavy metals, nutrients and organic pollutants from various types of wastewater. This study offers a wide-ranging scrutiny of the potential use of plant biomasses as feedstock for bioenergy generation, focusing on both biochemical and thermochemical conversion processes. In addition, we provide information regarding the conversion of biomass into animal feed, focusing on ruminants, fish and poultry, the manufacture of fertilizers and the use of treated water. Overall, we offer a clear idea of the technoeconomic benefits of using macrophytes for the treatment of wastewater and the challenges that need to be rectified to make this cradle-to-cradle concept more efficient.

Comparative Study of the Convertibility of Pretreated Miscanthus Straw Using Enzyme Preparations Produced by Different Recombinant Strains of Penicillium verruculosum

Non-edible cellulosic biomass from perennial herbaceous plants is a promising and abundant feedstock for replacing slow-growing woody plants used in biotechnological applications. Herbaceous plant biomass, as other types of plant biomass, requires pretreatment before biochemical conversion. In this study, miscanthus straw was pretreated using different methods and subjected to enzymatic hydrolysis with Penicillium verruculosum enzyme complexes under laboratory conditions. The convertibility after enzymatic hydrolysis varied from 15% to 66%, depending on the pretreatment method. Dilute alkaline pretreatment showed the highest convertibility compared to other methods, reaching up to 66%. The efficiency of dilute acid pretreatment was relatively low compared to other methods. The maximum convertibility was 37% for sulfuric acid pretreatment (the least efficient) and 51% for nitric acid. Convertibility was almost equal with 43% for white liquor and 46% for hot water. The glucose-to-xylose ratio was 4.7:1 for dilute alkaline pretreatment and 11–13:1 for white liquor. Both sulfuric and nitric acid resulted in a low xylose content in the enzymatic hydrolysates. Low-xylose hydrolysates with less than 2% of the glucose amount can be produced by hot water pretreatment. Preparation C, enriched with endoglucanase I from T. reesei and endoglucanase II from P. verruculosum, was found to be the most effective of the different enzyme preparations (EPs) tested.

Biomass: A Versatile Resource for Biofuel, Industrial, and Environmental Solution

Biomass, noted for its adaptability, has various applications in biofuel generation, industrial use, and environmental cleaning. This study looks into the multiple roles of biomass as a renewable energy source, with a particular emphasis on its vital contribution to biofuel production. Through a thorough evaluation of different conversion routes—thermal, biological, and physical—the study emphasizes thermochemical processes' efficiency, cost-effectiveness, and adaptability. Notably, technologies like gasification and quick pyrolysis are thoroughly investigated, followed by in-depth discussions of reactor optimization strategies to enhance performance and output. The complex structure of biomass, which is dominated by high-molecular-weight polysaccharides such as cellulose and hemicelluloses, demonstrates its significant potential for energy generation. Furthermore, the study categorizes biomass by content, origin, and conversion processes, resulting in a comprehensive inventory of available resources. Biomass from the agriculture and forestry industries, such as starch, sugar, lignocellulose, and organic wastes, is rigorously analyzed for energy production. Furthermore, various biomass processing techniques, including thermochemical, biochemical, and physicochemical conversions, are carefully tested in real-world applications to ensure their efficacy and viability. Beyond its importance in biofuel production, the article underlines biomass' versatility in satisfying industrial needs and contributing to environmental cleanup initiatives. This study lays the groundwork for informed decision-making and innovative solutions in various industries by providing a thorough understanding of biomass's various benefits and applications, including energy provision, industrial processes, and ecological restoration.

Application of waste biomass for the production of biofuels and catalysts: a review

AbstractSustainable development is imperative, and the worldwide energy production must focus on the transition from petroleum derivatives to biomass-based biofuels and bioproducts to achieve a bio-based economy. The global interest in the processing of waste biomass to obtain bio-based products is continuously increasing. However, biorefineries have not yet been consolidated. The effective conversion of biomass components for the generation of value-added biochemicals and biofuels is a determining factor for the economic success of biorefineries. Therefore, exhaustive research has been performed to consolidate the biorefinery industry. This review summarizes the current advances in liquid biofuel production and solid catalysts prepared from waste biomass, as well as their advantages, drawbacks, and statistical data. It offers an extensive perspective, covering conventional methods and cutting-edge techniques such as biochemical and thermochemical biomass conversion technologies (e.g., hydrolysis, fermentation, pyrolysis, and gasification) to produce bioalcohols, biodiesel, renewable diesel, bio-jet, and bio-oil. In addition, the preparation of heterogeneous catalysts using residual biomass and different synthesis routes and their role in biofuel production were analyzed. This review contributes to the analysis of the importance of identifying and valorizing a wide spectrum of raw materials (i.e., urban, forestry, industrial, and agricultural) that have the potential to be used as catalyst precursors and biofuel feedstock. Finally, a techno-economic analysis, the main challenges, and the future scope of the diverse methods used to prepare biofuels and catalysts are discussed. This review examines numerous aspects from biomass to catalysts, thus providing relevant information for researchers, students, policymakers, and industry experts. Graphical abstract

Thermally enhanced solid-liquid separation process in food waste biorefinery: modelling the anaerobic digestion of solid residues.

The biochemical valorization potential of food waste (FW) could be exploited by extracting decreasing added-value bio-based products and converting the final residues into energy. In this context, multi-purpose and versatile schemes integrating thermal and biochemical conversion processes will play a key role. An upstream thermal pretreatment + solid-liquid separation unit was here proposed to optimize the conversion of the liquid fraction of FW into valuable chemicals through semi-continuous fermentation process, and the conversion of the residual solid fraction into biomethane through anaerobic digestion. The solid residues obtained after thermal pretreatment presented a higher soluble COD fraction, which resulted in higher methane production with respect to the raw residues (0.33 vs. 0.29 Nm3CH4 kg-1VSfed) and higher risk of acidification and failure of methanogenesis when operating at lower HRT (20d). On the contrary, at HRT = 40 d, the pretreatment did not affect the methane conversion rates and both tests evidenced similar methane productions of 0.33 Nm3CH4 kg-1VSfed. In the reactor fed with pretreated residue, the association of hydrogenotrophic methanogens with syntrophic bacteria prevented the acidification of the system. Modelling proved the eligibility of the FW solid residues as substrates for anaerobic digestion, given their small inert fractions that ranged between 0% and 30% of the total COD content.

Emerging Sustainability in Carbon Capture and Use Strategies for V4 Countries via Biochemical Pathways: A Review

The world is moving towards decarbonization policies in the energy and industrial sectors to bring down carbon dioxide release and reach net zero emissions. Technologies to capture CO2 and use it as a feedstock to produce CO2-based chemicals and biofuels via chemical or biochemical conversion pathways can potentially reduce the amount of CO2 released. The paper serves the innovative scientific knowledge for CO2 transformation via a biochemical pathway to microalgal biomass with its subsequent treatment to biofuels and bioproducts assuming milder climatic conditions (Central or Eastern Europe, Visegrad countries or climatically related world regions). The recent trends were critically reviewed for microalgal biorefinery to reach the sustainability of microalgal-based chemicals with added value, digestion, hydrothermal liquefaction, pyrolysis, and gasification of microalgal residues. Knowledge-based chemical process engineering analysis, systematic data synthesis, and critical technical evaluation of available life cycle assessment studies evaluated the sustainability of microalgal biorefinery pathways. The research showed that biological CO2 fixation using water, seawater or wastewater to produce third-generation biomass is a promising alternative for bioethanol production via pretreatment, enzymatic hydrolysis, digestion, and distillation, and can be realized on a large scale in an economically viable and environmentally sound manner. Its best economically promising and sustainable pathway is perceived in producing microalgal-based nutraceuticals, bioactive medical products, and food products such as proteins, pigments, and vitamins. Machine learning methods for data mining, process control, process optimization, and geometrical configuration of reactors and bioreactors are the crucial research needs and challenges to implementing microalgal biorefinery in an operational environment.

Methane fermentation to methanol (biological gas‐to‐liquid process) using Methylotuvimicrobium buryatense5GB1C

AbstractMethanol is a potential alternate liquid transportation fuel for blending with gasoline. Biochemical conversion of methane to methanol is a green process for methanol production. This paper reports biochemical methanol production using type I γ‐proteobacteria Methylotuvimicrobium buryatense, which has particular importance from the viewpoint of scalable biological gas to liquid processes for industrial application. A statistical design of experiments (at the serum bottle level) was used to optimize fermentation parameters. Enhancement in methanol accumulation was attempted using methanol dehydrogenase inhibitors. This was followed by a validation experiment run in a bioreactor at optimum conditions. At optimum conditions (pH = 7, phosphate concentration = 140 mM, temperature = 25°C) and optical density (600 nm) of 0.3, a methanol titer of 8.54 mM was achieved in 24 h (methane conversion = 20.8%). The addition of a methanol dehydrogenase inhibitor (0.5 mM Ethylenediaminetetraacetic acid) enhanced the methanol concentration to 10.37 mM. Experiments in a 3.7 L bioreactor using 1.68 bar headspace pressure and optical density (600 nm) of 0.1 yielded 23.7 mM methanol in 24 h (methane conversion = 47.8%). The methanol titers obtained using M. buryatense 5GB1C in 24 h fermentation are significantly higher than several previously reported methanotrophs. These results demonstrate the potential of M. buryatense 5GB1C for the biochemical synthesis of methanol.

Biomass and bioenergy potentials of bioresidues: assessment methodology development and application to the region of Lafões

AbstractBioenergy research aims to uncover the potentials of biological residues. Regional-specific characterization of such potentials is needed to improve the use of local resources, decisions on bioenergy conversion routes, and services within global efforts against climate change. The definition and calculation of the theoretical and technical biomass and bioenergy potentials are keys for developing sustainable use pathways at a regional level. The present work develops a methodology where theoretical framework, quantification methods, and values for the necessary parameters, to assess regional biomass and bioenergy potentials, are considered. The region of Lafões (Portugal) is the case study to illustrate the application of the methods, resulting in three bioresidue categories (agricultural by-products, forestry residues, and municipal waste) and two bioenergy conversion routes (biochemical and thermochemical). The biochemical conversion route revealed a technical energy potential of 765 TJ yr−1, comparing favourably with the 543 TJ yr−1 achieved by the thermochemical route. Also, the environmental and economic performances, associated with the implementation of bioenergy technologies, are possibly better achieved through the biochemical route, to be assessed through life cycle analyses and life cycle costing. Regardless of action priorities, the two conversion routes combined can potentially cover the entire current electrical energy demand of the region. This should also be appraised with expectations in mind for both flexible bioenergy services (with other renewables) and for bioenergy usage in applications which are difficult to defossilize.

Permanganate (PM) pretreatment improves medium-chain fatty acids production from sewage sludge: The role of PM oxidation and in-situ formed manganese dioxide

Medium-chain fatty acids (MCFAs) production from sewage sludge is mainly restricted by the complex substrate structure, competitive metabolism and low electron transfer rate. This study proposes a novel permanganate (PM)-based strategy to promote sludge degradation and MCFAs production. Results show that PM pretreatment significantly increases MCFAs production, i.e., attaining 12,036 mg COD/L, and decreases the carbon fluxes of electron acceptor (EA)/electron donor (ED) to byproducts. Further analysis reveals that PM oxidation enhances the release and biochemical conversion of organic components via disrupting extracellular polymers (EPS) structure and reducing viable cells ratio, providing directly available EA for chain elongation (CE). The microbial activity positively correlated with MCFAs generation are apparently heightened, while the competitive metabolism of CE (i.e., methanogensis) can be completely inhibited. Accordingly, the functional bacteria related to critical bio-steps and dissimilatory manganese reduction are largely enriched. Further mechanism exploration indicates that the main contributors for sludge solubilization are 1O2 (61.6 %) and reactive manganese species (RMnS), i.e., Mn(V)/Mn(VI) (22.3 %) and Mn(III) (∼16.1 %). As the main reducing product of PM reaction, manganese dioxide (MnO2) can enable the formation of microbial aggregates, and serve as electron shuttles to facilitate the carbon fluxes to MCFAs during CE process. Overall, this strategy can achieve simultaneous hydrogen recovery, weaken competitive metabolisms and provide electron transfer accelerator for CE reactions.

A review on emerging technologies and machine learning approaches for sustainable production of biofuel from biomass waste

Biomass waste must be treated and disposed off properly, as it concerns the possibility of deposition in the environment. This could worsen the ecosystem by promoting the growth of pathogens, producing poisonous fumes, releasing ammonia and other dangerous gases into the atmosphere. Therefore, researchers are exploring different direct biomass waste applications. One such application is biotechnological options with financial and environmental benefits like lowering the consumption of fossil fuels, reducing harmful emissions, accelerating the synthesis of low-cost raw materials, and fostering an environment that is favourable for a broad range of microorganisms. In recent years, biofuel has emerged as the primary source of bio-energy by replacing fossil fuels that can meet the global energy demands and lower greenhouse gas (GHG) emissions. This review explores the potential of biomass waste conversion techniques and examines the production of biofuels to achieve zero carbon emissions. Critical research has also been done to improve the anaerobic treatment method of the biochemical conversion method. Apart from these, the advancements in the study of metabolic engineering techniques and artificial intelligence in the production of biofuel and strategies along with microbial chassis to enhance production of biofuel in an efficient manner were also studied. Finally, challenges and future perspectives of biofuels were delineated.

Mono-Digestion of 5-Hydroxymethylfurfural Process-Wastewater in Continuously Operated Anaerobic Filters: A Cascade Utilization Approach

A proper remedy for the overexploitation of biomass and biobased materials in the bioeconomy is the valorization of biorefineries’ side streams into meaningful products. Hence, in pursuit of a cascade utilization of renewables, a unique biorefinery byproduct was investigated for its biogas potential, specifically methane, in continuously operated anaerobic filters. For this purpose, 5-Hydroxymethylfurfural process-wastewater, after supplementation of necessary nutrients, was diluted down to 10, 20, 30, 40, and 50 gCOD/L concentrations and thereafter tested individually at 43 °C and 55 °C. Maximum methane conversion efficiency at either temperature was observed for test substrates with 10 gCOD/L and 20 gCOD/L concentrations. At 43 °C, the anaerobic filters exhibited their highest biogas yields when supplied with the 30 gCOD/L feedstock. Further exposure of the mesophilic and thermophilic consortia to the ensuing 5-Hydroxymethylfurfural process-wastewater dilutions compromised the stability of the anaerobic process due to the soaring concentrations of short-chained volatile fatty acids. The supplementation of necessary nutrients to unlock the methane potential of the given recalcitrant substrate appears insufficient. Techniques like micro aeration, photolysis, or the use of activated carbon in the fixed bed might have the ability to enhance the biochemical methane conversion of such feedstock; otherwise, the introduction of trace elements alone may be adequate if aiming for platforms (volatile fatty acids) via anaerobic technologies.

Recent Developments in Lignocellulosic Biofuel Production with Nanotechnological Intervention: An Emphasis on Ethanol

Biofuel, an inexhaustible fuel source, plays a pivotal role in the contemporary era by diminishing the dependence on non-renewable energy sources and facilitating the mitigation of CO2 emissions. Due to the many constraints in existing technology and the resulting increased costs, the production of biofuels on a large scale is a laborious process. Furthermore, the methods used to convert varied feedstock into the intended biofuel may vary based on the specific techniques and materials involved. The demand for bioethanol is increasing worldwide due to the implementation of regulations by world nations that mandates the blending of bioethanol with petrol. In this regard, second-generation bioethanol made from lignocellulosic biomass is emerging at a rapid rate. Pre-treatment, hydrolysis, and fermentation are some of the technical, practical, and economic hurdles that the biochemical conversion method must overcome. Nanoparticles (NPs) provide a very effective approach to address the present obstacles in using biomass, due to their selectivity, energy efficiency, and time management capabilities, while also reducing costs. NPs smaller dimensions allow them to be more effective at interacting with lignocellulosic components at low concentrations to release carbohydrates that can be utilized to produce bioethanol. This article provides a concise overview of various biofuels and the nanotechnological advancements in producing it, with a particular emphasis on ethanol. It provides a detailed discussion on the application of nanotechnology at each stage of ethanol production, with a particular emphasis on understanding the mechanism of how nanoparticles interact with lignocellulose.

Efficacy and safety of tenofovir disoproxil fumarate versus entecavir in the treatment of acute-on-chronic liver failure with hepatitis B: a systematic review and meta-analysis.

Oral nucleoside (acid) analogues (NAs) are recommended for patients with acute-on-chronic liver failure (ACLF) associated with hepatitis B virus (HBV-ACLF). The efficacy and safety of tenofovir (TDF) and entecavir (ETV) in these patients remain unclear. A comprehensive literature search in PubMed, Web of Science, The Cochrane Library, and Embase database was conducted to select studies published before December 2022 on TDF or ETV for HBV-ACLF. The primary outcomes were survival rates at 4, 12, and 48 weeks. Secondary outcomes were virologic and biochemical responses, serum antigen conversion, liver function score, and safety. Four prospective and one retrospective cohort studies were selected. The overall analysis showed comparable survival rates at 4, 12, and 48 weeks for all patients receiving TDF or ETV (4-week: RR = 1.17, 95% CI: 0.90-1.51, p = 0.24; 12-week: RR = 1.00, 95% CI: 0.88-1.13, p = 0.94; 48-week: RR = 0.96, 95% CI: 0.58-1.57, p = 0.86). Child-Turcotte-Pugh (CTP) score and model for end-stage liver disease (MELD) score at 12 weeks were comparable in both groups but lower than baseline (CTP: SMD = -0.75, 95% CI:-2.81-1.30, p = 0.47; MELD: SMD = -1.10, 95% CI:-2.29-0.08, p = 0.07). At 48 weeks, estimated glomerular filtration rate (eGFR) levels were found to decrease to different degrees from baseline in both the TDF and ETV groups, and the decrease was greater in the TDF group than in the ETV group. No significant differences were found in biochemical, virologic response, and serum antigen conversion between the two groups during the observation period. TDF treatment of HBV-ACLF is similar to ETV in improving survival, liver function, and virologic response but the effects on renal function in two groups in the long term remain unclear. More and larger long-term clinical trials are required to confirm these findings.

Integrating Fermentation Engineering and Organopalladium Chemocatalysis for the Production of Squalene from Biomass-Derived Carbohydrates as the Starting Material

The transition from fossil resources to renewable biomass for the production of valuable chemicals and biobased fuels is a crucial step towards carbon neutrality. Squalene, a valuable chemical extensively used in the energy, healthcare, and pharmaceutical fields, has traditionally been isolated from the liver oils of deep-sea sharks and plant seed oils. In this study, a biochemical synergistic conversion strategy was designed and realized to convert glucose to squalene by combining fermentation technology in yeast with reductive coupling treatment of dienes. First, glucose derived from hydrolysis of cellulose was used as a renewable resource, using genetically engineered Saccharomyces cerevisiae as the initial biocatalyst to produce β-farnesene with a titer of 27.6 g/L in a 2.5 L bioreactor. Subsequently, intermediate β-farnesene was successfully converted to squalene through the organopalladium-catalyzed reductive coupling reaction involving the formation of Pd(0)L2 species. Under mild reaction conditions, impressive β-farnesene conversion (99%) and squalene selectivity (100%) were achieved over the Pd(acac)2 catalyst at a temperature of 75 °C in an ethanol solvent after 5 h. This advancement may provide insights into broadening squalene production channels and accessing the complex skeletons of natural terpenoids from biorenewable carbon sources, offering practical significance and economic benefits.

Development of Cost-Effective Fuel Briquette with Poultry Manure

Biomass can be converted into either heat energy or electrical or energy carriers using both thermo-chemical and bio-chemical conversion. Briquetting is a process where untreated biomass is converted into homogeneous, uniformly sized high density solid blocks. Briquettes are used in boilers, heating plants, thermal power stations and by individual households for heating. Present study focuses on using poultry manure with rice husk and saw dust. Poultry manure mixed with rice husk or saw dust by 60:40 ratio provides comparatively higher bond strength. Calorific value varies significantly with the use of poultry manure and tree leaves as well as its production cost. Pure rice husk contains higher calorific value (HCV) 12.6 MJ/Kg where adding poultry manure reduces its value to 10.3 MJ/Kg and Saw dust shows 10.4 MJ/Kg where pure saw dust has 16.3 MJ/Kg in 60:40 ratios with poultry manure. Addition of 20% tree leaves on weight basis ratio of 40:40:20 with base materials and poultry manure shows 10.5 MJ/Kg and 11.7 MJ/Kg respectively for rice husk and saw dust. Competitive price of briquette for 60:40 ratios with Poultry Manure shows 6 BDT/Kg and 5BDT/Kg when secondary material is added. Moreover, if the machine capacity increases the price is reduced.
 Dhaka Univ. J. Sci. 71(2): 95-103, 2023 (July)

Bacterial cellulose/gum Arabic composite production by in-situ modification from lavender residue hydrolysate

In this study, bacterial cellulose/gum Arabic composite (BC/GA) was synthesized by in-situ modification from lavender residue hydrolysate for the first time. The in-situ modification with GA adding showed great beneficial effect for BC/GA synthesis. Both the product (BC or BC/GA) yield and the product (BC or BC/GA) production per sugars consumption increased greatly by the in-situ modification when compared with the fermentation without GA adding (2.90 g/L vs. 0.91 g/L, and 0.461 g/g vs. 0.138 g/g). It is hypothesized that the combination of BC and GA is the main mechanism for the beneficial effect of the in-situ modification, and the scanning electron microscope (SEM) images confirmed this hypothesis. GA adding showed little effect on the rheological properties of lavender residue hydrolysate, and this environment was suitable for the combination of BC and GA. The in-situ modification had an obvious influence on the crystallinity index and the thermal stability of BC/GA, but affected little on its functional groups and cellulose structural framework. Besides BC/GA synthesis and structure, the in-situ modification could also alter the texture properties of BC/GA. Overall, this study can offer some useful information for the biochemical conversion from green and cost-effective lavender residue hydrolysate to attractive biomaterial BC/GA.

Biomethanol production from renewable resources: a sustainable approach.

The abundant availability of various kinds of biomass and their use as feedstock for the production of gaseous and liquid biofuels has been considered a viable, eco-friendly, and sustainable mode of energy generation. Gaseous fuels like biogas and liquid fuels, e.g., bioethanol, biodiesel, and biomethanol derived from biological sources, have been theorized to produce numerous industrially relevant organic compounds replacing the traditional practice of employing fossil fuels as a raw material. Among the biofuels explored, biomethanol has shown promising potential to be a future product addressing multifactorial issues concerning sustainable energy and associated process developments. The presented mini-review has explored the importance and application of biomethanol as a value-added product. The biomethanol production process was well reviewed by focusing on different thermochemical and biochemical conversion processes. Syngas and biogas have been acknowledged as potential resources for biomethanol synthesis. The emphasis on biochemical processes is laid on the principal metabolic pathways and enzymatic machinery involved or used by microbial physiology to convert feedstock into biomethanol under normal temperature and pressure conditions. The advantage of minimizing the cost of production by utilizing suggested modifications to the overall process of biomethanol production that involves metabolic and genetic engineering in microbial strains used in the production process has been delineated. The challenges that exist in our current knowledge domain, impeding large-scale commercial production potential of biomethanol at a cost-effective rate, and strategies to overcome them along with its future scenarios have also been pointed out.

Aviation fuel production pathways from lignocellulosic biomass via alcohol intermediates – A technical analysis

In order to achieve the goal of limiting global warming to 1.5 °C, also the growing aviation industry needs to take measures to reduce their greenhouse gas emissions. Various renewably sourced aviation fuels can significantly reduce greenhouse gas emissions and most of them, except for example liquid hydrogen or LNG, can be used in the existing infrastructure without airport or aircraft modifications. As most of these renewably sourced fuel types are not (yet) produced at commercial scale, many technological assessment parameter (e.g. carbon or energy efficiency) are uncertain. Thus, the goal of this study is to compare two different process routes, both being based on biochemical and thermochemical conversion steps. The processes evaluated against conversion efficiency of the available raw feedstock and process energy requirements. The evaluation uses theoretical and biochemical carbon efficiency as well as energy efficiency as indicators. A steady-state flowsheet simulation for two biogenic process paths via biogas and bioethanol as intermediate products is carried out on the basis of literature data. In addition, the optional use of solid residue from the biotechnological process step by combustion for direct heat supply cases are studied. In the ethanol-based route, about 23% of the carbon in the feed can be recovered as kerosene, whereas this is only about 19% in the biogas route. Simultaneously, the ethanol-based route without the combustion of the residue has an energy efficiency of 28%, while the biogas route has an efficiency of 24%.

Cell membrane permeabilization by pulsed electric field treatment impacts biochemical conversions and the volatile profile of broccoli stalks

In this study, pulsed electric fields (PEF) treatments at low field strengths were applied to broccoli stalks. The effect of varying electric field strength and total specific energy input was investigated on membrane integrity by conductivity measurements and on the volatile profile analyzed via HS-SPME-GC-MS. This work showed that PEF at low field strengths can induce membrane disintegration in broccoli stalks. A substantial effect of implementing different total specific energy inputs between 2.19 and 41.10 kJ/kg at a fixed low electrical field strength on the resulting cell membrane disintegration and volatile profiles of incubated broccoli stalks was observed. Contrarily, varying the electrical field strength above 1.01 kV/cm at 2.50 and 8.00 kJ/kg did result in comparable membrane disintegration and volatile profiles of incubated broccoli stalks. The results implied that the specific energy input has a more prominent effect to steer the volatile profile of broccoli stalks compared to the field strength under the conditions tested.

Microbial pretreatment of camelina straw and switchgrass by Trametes versicolor and Phanerochaete chrysosporium to improve physical quality and enhance enzymatic digestibility of solid biofuel pellets

In this study, optimization of solid-state fermentation of Camelina sativa residues (camelina straw, CS) and Panicum virgatum (switchgrass, SG) by Trametes versicolor 52J (TV52J), Trametes versicolor m4D (TVm4D), and Phanerochaete chrysosporium (PC) was conducted. At optimal conditions, the tensile strength, unit density and mass loss for CS pellets were 6.2 MPa, 1139 kg m−3, and 33%, respectively after 31 d pretreatment by TVm4D, while for SG pellets, they were 1.6 MPa, 1244 kg m−3 , and 13.8%, respectively after 32 d pretreatment by TVm4D. Although the holocellulose content of microbially pretreated CS and SG pellets dropped from 58.6 to 36.7%, and from 66.2 to 46.3%, respectively, the glucose yield of CS pellets increased from 12.9 to 61.1% with a corresponding xylose yield increase from 14.7 to 60.1%. The glucose and xylose yield of SG increased from 10.9 to 59.9% and 13.4 to 35.7%, respectively. It can be concluded that microbial pretreatment contributed to mass loss of the samples but trivially affected the energy content and significantly boosted the physical properties and enzymatic digestibility of the treated pellets. The microbially pretreated CS is recommended for densification and combustion while the microbially pretreated SG is more suitable for biochemical conversion.