Kinetics and Reactor Design Principles of Volatile Fatty Acid Ketonization for Sustainable Aviation Fuel Production
Not Available
09 BIOMASS FUELS↗
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Membrane electrolysis distillation for volatile fatty acids extraction from pH-neutral fermented wastewater
Not Available
Lu, Sidan (ORCID:0000000250089467)↗
Optimizing dietary rumen-degradable starch to rumen-degradable protein ratio improves lactation performance and nitrogen utilization efficiency in mid-lactating Holstein dairy cows
The dietary rumen-degradable starch (RDS) to rumen-degradable protein (RDP) ratio, denoted as the RDS-to-RDP ratio (SPR), has been proven to enhance in vitro rumen fermentation. However, the effects of dietary SPR in vivo remain largely unexplored. This study was conducted to investigate the effect of dietary SPR on lactation performance, nutrient digestibility, rumen fermentation patterns, blood indicators, and nitrogen (N) partitioning in mid-lactating Holstein cows. Seventy-two Holstein dairy cows were randomly assigned to three groups (24 head/group), balanced for (mean ± standard deviation) days in milk (116 ± 21.5), parity (2.1 ± 0.8), milk production (42 ± 2.1 kg/d), and body weight (705 ± 52.5 kg). The cows were fed diets with low (2.1, control), medium (2.3), or high (2.5) SPR, formulated to be isoenergetic, isonitrogenous, and iso-starch. The study consisted of a one-week adaptation phase followed by an eight-week experimental period. The results indicated that the high SPR group had a lower dry matter intake compared to the other groups ( p < 0.05). A quadratic increase in milk yield and feed efficiency was observed with increasing dietary SPR ( p < 0.05), peaking in the medium SPR group. The medium SPR group exhibited a lower milk somatic cell count and a higher blood total antioxidant capacity compared to other groups ( p < 0.05). With increasing dietary SPR, there was a quadratic improvement ( p < 0.05) in the total tract apparent digestibility of crude protein, ether extract, starch, neutral detergent fiber, and acid detergent fiber. Although no treatment effect was observed in rumen pH, the rumen total volatile fatty acids concentration and microbial crude protein synthesis increased quadratically ( p < 0.05) as dietary SPR increased. The molar proportion of propionate linearly increased ( p = 0.01), while branched-chain volatile fatty acids linearly decreased ( p = 0.01) with increasing dietary SPR. The low SPR group (control) exhibited higher concentration of milk urea N, rumen ammonia N, and blood urea N than other groups ( p < 0.05). Despite a linear decrease ( p < 0.05) in the proportion of urinary N to N intake, increasing dietary SPR led to a quadratic increase ( p = 0.01) in N utilization efficiency and a quadratic decrease ( p < 0.05) in the proportion of fecal N to N intake. In conclusion, optimizing dietary SPR has the potential to enhance lactation performance and N utilization efficiency. Based on our findings, a medium dietary SPR (with SPR = 2.3) is recommended for mid-lactating Holstein dairy cows. Nevertheless, further research on rumen microbial composition and metabolites is warranted to elucidate the underlying mechanisms of the observed effects.
Chen, Panliang↗
New perspectives on butyrate assimilation in Rhodospirillum rubrum S1H under photoheterotrophic conditions
Background: The great metabolic versatility of the purple non-sulfur bacteria is of particular interest in green technology. Rhodospirillum rubrum S1H is an α-proteobacterium that is capable of photoheterotrophic assimilation of volatile fatty acids (VFAs). Butyrate is one of the most abundant VFAs produced during fermentative biodegradation of crude organic wastes in various applications. While there is a growing understanding of the photoassimilation of acetate, another abundantly produced VFA, the mechanisms involved in the photoheterotrophic metabolism of butyrate remain poorly studied. Results: In this work, we used proteomic and functional genomic analyses to determine potential metabolic pathways involved in the photoassimilation of butyrate. We propose that a fraction of butyrate is converted to acetyl-CoA, a reaction shared with polyhydroxybutyrate metabolism, while the other fraction supplies the ethylmalonyl-CoA (EMC) pathway used as an anaplerotic pathway to replenish the TCA cycle. Surprisingly, we also highlighted a potential assimilation pathway, through isoleucine synthesis and degradation, allowing the conversion of acetyl-CoA to propionyl-CoA. We tentatively named this pathway the methylbutanoyl-CoA pathway (MBC). An increase in isoleucine abundance was observed during the early growth phase under butyrate condition. Nevertheless, while the EMC and MBC pathways appeared to be concomitantly used, a genome-wide mutant fitness assay highlighted the EMC pathway as the only pathway strictly required for the assimilation of butyrate. Conclusion: Photoheterotrophic growth of Rs. rubrum with butyrate as sole carbon source requires a functional EMC pathway. In addition, a new assimilation pathway involving isoleucine synthesis and degradation, named the methylbutanoyl-CoA (MBC) pathway, could also be involved in the assimilation of this volatile fatty acid by Rs. rubrum.
59 BASIC BIOLOGICAL SCIENCES↗
Catalytic upgrading of wet waste-derived carboxylic acids to sustainable aviation fuel and chemical feedstocks
We develop a continuous catalytic process to convert wet waste-derived volatile fatty acids into sustainable aviation fuel and aromatic chemicals.
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Optimization of Thermal Pretreatment of Food Waste for Maximal Solubilization
Not provided.
Engineering↗
Integrated Anaerobic Membrane Bioreactor (AnMBR) – electro assisted fermentation platform for total resource recovery from diverse wastewaters
The overall objective of the project was to demonstrate a successful wastewater resource recovery platform comprising an Anaerobic Membrane Bioreactor (AnMBR) to achieve >50% Carbon sequestration efficiency as Volatile Fatty Acids (VFAs) or as methane gas from agricultural (animal feeding operations) wastewater along with the generation of final water exceeding Biological Nutrient Removal (BNR) standards for indirect potable reuse by coupling with constructed wetlands has been successfully accomplished. The AnMBR achieved stable performance over 350 days, removing 80–90% of COD and BOD₅ and recovering methane (0.17±0.07 L CH4/g COD at 66.5±0.03% v/v) at 3-5 LMH flux and 5-9 days HRT with 3-5% w/v total solids. Phosphorus recovery via CaO addition in an 80-L coagulation-flocculation-sedimentation unit ranged from 40.6% to 99.7%, yielding products with 11.4–13.6% P content and citric acid solubility of 32–38.6% P, comparable to rock phosphate mineral. Ammonium adsorption achieved ~94.5% recovery with exchange capacity of 10 – 16 g NH4-N/kg clinoptilolite. The CW polishing step met Kansas discharge standards for BOD5 and TN (<30 and <10 mg /L,) and approached the TP standard (~2.5 – 4 mg P/L). These findings have either already resulted in two peer reviewed publications, two patent applications, and one publication in conference proceedings.
42 ENGINEERING↗
Evaluation of digestively resistant or soluble fibers, short- and medium-chain fatty acids, trace minerals, and antibiotics in nonchallenged nursery pigs on performance, digestibility, and intestinal integrity
Abstract Three experiments (EXP) were conducted to determine the effect of feed additives on performance, intestinal integrity, gastrointestinal volatile fatty acids (VFA), and energy and nutrient digestion in nonchallenged nursery pigs. In EXP 1, 480 pigs (6.36-kg body weight, BW) were placed into 96 pens with 5 pigs/pen, and allotted to 1 of 10 dietary treatments: 1) negative control containing no feed additive (NC), 2) NC + 44 mg chlortetracycline and 38.5 mg tiamulin/kg diet (CTsb), 3) NC + 5% resistant potato starch (RSpo), 4) NC + 5% soluble corn fiber (SCF), 5) NC + 5% sugar beet pulp (SBP), 6) NC + 0.30% fatty acid mix (FAM), 7) NC + 0.10% phytogenic blend of essential oils and flavoring compounds (PHY), 8) NC + 50 mg Cu and 1,600 mg zinc oxide/kg diet (CuZn), 9) NC + 5% resistant corn starch (RScn), and 10) NC + 0.05% β-glucan (BG) for 28 d. There was no impact of dietary treatment on BW gain or feed intake (P ≥ 0.22). Pigs fed diets containing SCF, CTsb, and RSpo resulted in microbial community differences compared to pigs fed the NC (P < 0.05). In EXP 2, 48 barrows (12.8 kg BW) were selected at the end of EXP 1 and fed the same dietary treatments they had previously received: 1) NC, 2) NC + 5% RScn, 3) NC + 5% SCF, and 4) NC + FAM for 8 d. There was no effect of feeding diets containing RScn, SCF, or FAM on in vivo intestinal permeability (P ≤ 0.21). Ileal or colon pH, concentrations of VFA did not differ due to dietary treatment (P ≥ 0.36), but pigs fed diets containing FAM resulted in a greater butyric acid concentration in the cecum compared to pigs fed the NC (P ≤ 0.05). In EXP 3, 156 pigs (6.11 kg BW) were placed into 52 pens with 3 pigs/pen and allotted to 1 of 4 dietary treatments arranged in a factorial manner: 1) NC, 2) NC + 5% RSpo, 3) NC + 0.30% FAM, and 4) NC + 5% RSpo + 0.30% FAM for 24 d. Feeding pigs diets containing RSpo did not affect BW gain (P = 0.91) while pigs fed diets containing FAM grew improved BW gain (P = 0.09). Colonic butyric acid concentrations were greater in pigs fed diets containing RSpo (P = 0.03), while pigs fed diets containing FAM exhibited reduced total VFA concentrations (P = 0.11). The results indicate that supplementing diets with digestively resistant but fermentable fibers, short- and medium-chain fatty acids, or antibiotics do not have a consistent effect, positive or negative, on markers of intestinal integrity or barrier function, intestinal VFA patterns, ATTD of energy and nutrients, or on pig performance.
Agriculture↗
Turicibacter bilis sp. nov., a novel bacterium isolated from the chicken eggshell and swine ileum
Three novel, anaerobic, Gram-positive bacteria were isolated from the eggshell of two separate white leghorn chicken flocks and the ileum of a healthy pig, and designated MMM721 T , ISU324 and PIG517 respectively. Cells were pleomorphic and capable of forming long chains of rods or coccoid clusters. Phylogenetic analysis of the 16S rRNA gene sequences identified these strains to be within the genus Turicibacter, of which only one species, Turicibacter sanguinis, has been formally described. However, whole genome sequencing of novel isolates returned a digital DNA–DNA hybridization value of 22.5% and average nucleotide identity (ANI) values of 76.4% (ANIb) and 86.0% (ANIm), indicating divergence between the type strain MMM721 T and T. sanguinis, suggesting the strains represented a novel species. The major fatty acid methyl esters of strain MMM721 T were C 16:0 , C 18:1 ω7c and C 18:0 . The strains mainly produced the volatile fatty acid lactate, along with smaller amounts of acetate and butyrate. Together, these data indicate that MMM721 T , along with ISU324 and PIG517, represent a novel species within the genus Turicibacter. We propose the name Turicibacter bilis sp. nov. for the species. The type strain is MMM721 T (=ATCC TSD-238 T =CCUG 74757 T ).
59 BASIC BIOLOGICAL SCIENCES↗
Towards improved conversion of wet waste to jet fuel with atomic layer deposition-coated hydrodeoxygenation catalysts
The conversion of wet waste-derived volatile fatty acids into jet fuel-range hydrocarbons is a promising route for increasing the production of sustainable aviation fuel; however, the cost and moderate alkane selectivity of Pt-based hydrodeoxygenation catalysts present challenges for commercialization. Here, to address this, we used atomic layer deposition to apply TiO 2 overcoats to Pt/Al 2 O 3 catalysts and create new interface sites that exhibited 8 times higher site time yield of the desirable n-alkane product than uncoated catalyst. Through TPR/TPD, XPS, CO DRIFTS, and DFT calculations, we found that the increased selectivity of the ALD-coated catalyst was due to the creation of O vacancies at the Pt-TiO 2 interface under reducing conditions, resulting in new Ti 3+ acid sites near the active metal. Maximum conversion and alkane selectivity during HDO was achieved with an ALD-coated 0.5% wt Pt catalyst, indicating that TiO 2 ALD can be used to maximize the utility of precious-metal catalysts.
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Hydrogen production from full-strength corn stover fermentation effluent in single-chamber replaceable-cathode microbial electrolysis cells
Lignocellulosic residual biomass generated by the agricultural sector is an abundant feedstock for biohydrogen production via dark fermentation. However, this process is intrinsically inefficient, converting only ~30% of the reductant energy into H2 and leaving substantial amounts of reduced byproducts. These byproducts, mostly found in the fermentation effluents, can be further valorized in microbial electrolysis cells (MECs) to enhance the overall H2 recovery. However, current MEC configurations are typically dual- or single-chamber systems, yet both suffer from key inefficiencies. Dual-chamber systems rely on proton exchange membranes that are costly and prone to rapid biofouling, whereas single-chamber, membraneless systems are limited by reduced productivity due to H2 recycling and methanogenic consumption In this study, three single-chamber, 50-mL replaceable-cathode microbial electrolysis cells (RC-MECs) were 3D-printed and equipped with a physical separator to isolate anode and cathode compartments and limit H2 migration. Full-strength milled corn stover (MCS) fermentation effluent (COD of ~23.8 g-COD/L) was treated in fed-batch mode over two operational periods spanning 21 (Run 1) and 80 (Run 2) days. The RC-MECs exhibited comparable performance in both runs: after biofilm maturation, current densities exceeded 100 A/m²_cathode, COD removal reached up to 43%. Notably, extended RC-MECs operation led to a substantial methanogenic activity with the CH4 fraction in the cathode gas increasing to as high as 80% of the total biogas. Additions of a methanogenesis inhibitor 2-bromoethanesulfonate (2-BES) produced transient increases in hydrogen yields (11.51 and 5.12 L-H2/L_reactor/day in Runs 1 and 2, respectively); however, sustained 2-BES addition in subsequent cycles reduced total biogas production, decreased COD removal, and led to volatile fatty acid accumulation. Overall, single-chamber MECs can treat high-strength dark fermentation effluents while improving H2 recovery, but methanogenesis remains a key bottleneck, and complete long-term inhibition may be operationally unsustainable.
Hydrogen Production↗
Improving dairy manure hydrolysis and acidification through microbial community restructuring by adaptation to hyperthermophilic conditions
Dairy manure (DM) contributes significantly to greenhouse gas emissions and ecosystem degradation, yet its resistance to biodegradation hinders widespread bioprocessing applications. Lignocellulosic materials in DM pose a particular challenge because of their recalcitrance. Bioprocessing under hyperthermophilic (≥70 °C) conditions potentially offers an advantage over traditional fermentation temperatures due to enhanced activity of enzymes and the kinetics of enzymatic reactions. This can lead to a higher conversion rate and a greater extent of biomass hydrolysis and acidification. To test the validity of this hypothesis, the current study evaluated the efficacy of anaerobic hydrolysis and acidogenic fermentation of DM under mesophilic, thermophilic, and hyperthermophilic conditions. All inocula were adapted to corresponding temperatures but were derived from the same mesophilic source. Hyperthermophilic conditions resulted in superior DM hydrolysis efficiency (53%) compared to mesophilic (34%) and thermophilic (42%) conditions. The hyperthermophilic environment was particularly favorable to the decomposition of crude proteins and hemicellulose, which were reduced by 64% and 54%, respectively. Furthermore, hyperthermophilic fermentation also yielded the highest volatile fatty acid (VFA) production rate of 460 mg/L/day during the first four days, representing improvements of 50% and 90% over mesophilic and thermophilic conditions. In part, this was attributed to the enhanced production of branched-chain VFAs, including an increase of 6–10% in isobutyric acid and 12–13% in isovaleric acid. At hyperthermophilic conditions, however, there was no accumulation of VFAs during the days 5–8 of fermentation, which could be due to acetate conversion by the syntrophic acetate-oxidizing bacteria. A considerable gain in hydrolysis efficiency and VFA production rate were accompanied by a reduction in microbial diversity, which suggests that hyperthermophilic temperature is a favorable environment for the selection of organisms with enhanced DM hydrolysis and fermentation capabilities. A significantly increased relative abundance of xylanolytic Caldicoprobacter (23% of population) and proteolytic Thermovirga (9% of population) could be the major contributors to improved decomposition of hemicellulose and protein. As revealed by the techno-economic analysis, acidogenic fermentation of DM at 70 °C and a retention period of 4 days provides the greatest positive net present value, highest internal rate of return of 9.2%, and shortest investment payback period of 9 years. Furthermore, this study demonstrates that hyperthermophilic conditions enable superior deconstruction and bioconversion of lignocellulose-containing biomass into VFAs under reduced retention times, offering a promising approach for improving DM management and generating bioproducts.
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Microbial interactions with phosphorus containing glasses representative of vitrified radioactive waste
The presence of phosphorous in borosilicate glass (at 0.1 – 1.3 mol % P 2 O 5 ) and in iron-phosphate glass (at 53 mol % P 2 O 5 ) stimulated the growth and metabolic activity of anaerobic bacteria in model systems. Dissolution of these phosphorous containing glasses was either inhibited or accelerated by microbial metabolic activity, depending on the solution chemistry and the glass composition. The breakdown of organic carbon to volatile fatty acids increased glass dissolution. The interaction of microbially reduced Fe(II) with phosphorus-containing glass under anoxic conditions decreased dissolution rates, whereas the interaction of Fe(III) with phosphorous-containing glass under oxic conditions increased glass dissolution. Phosphorous addition to borosilicate glasses did not significantly affect the microbial species present, however, the diversity of the microbial community was enhanced on the surface of the iron phosphate glass. Results demonstrate the potential for microbes to influence the geochemistry of radioactive waste disposal environments with implication for wasteform durability.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Economic and sustainability prospects for wet waste valorization: The case for sustainable aviation fuel from arrested anaerobic digestion
Not Available
Wiatrowski, Matthew R. (ORCID:0000000206587178)↗
Renewable biohydrogen production from lignocellulosic biomass using fermentation and integration of systems with other energy generation technologies
Biohydrogen is a clean and renewable source of energy. It can be produced by using technologies such as thermochemical, electrolysis, photoelectrochemical and biological, etc. Among these technologies, the biological method (dark fermentation) is considered more sustainable and ecofriendly. Dark fermentation involves anaerobic microbes which degrade carbohydrate rich substrate and produce hydrogen. Lignocellulosic biomass is an abundantly available raw material and can be utilized as an economic and renewable substrate for biohydrogen production. Although there are many hurdles, continuous advancements in lignocellulosic biomass pretreatment technology, microbial fermentation (mixed substrate and co-culture fermentation), the involvement of molecular biology techniques, and understanding of various factors (pH, T, addition of nanomaterials) effect on biohydrogen productivity and yield render this technology efficient and capable to meet future energy demands. Further integration of biohydrogen production technology with other products such as bio-alcohol, volatile fatty acids (VFAs), and methane have the potential to improve the efficiency and economics of the overall process. In this study, various methods used for lignocellulosic biomass pretreatment, technologies in trends to produce and improve biohydrogen production, a coproduction of other energy resources, and techno-economic analysis of biohydrogen production from lignocellulosic biomass are reviewed.
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Molecular Transformation and Metabolic Insights of Microbial Electrolysis Treatment and Valorization of Post-hydrothermal Liquefaction Wastewater
Hydrothermal liquefaction (HTL) presents a promising approach for the conversion of wet waste into biocrude and biofuels. However, the post-hydrothermal liquefaction wastewater (PHW) poses significant challenges for treatment and valorization due to its high concentration and complex nature. In this study, we investigated the conversion pathways of major organic contaminants within the microbial electrolytic treatment of PHW from food waste HTL. To achieve this, we employed high-performance liquid chromatography (HPLC) and 2D nuclear magnetic resonance (NMR). Our findings demonstrate volatile fatty acids (VFAs) and monohydric and polyhydric alcohols were effectively transformed through the synergistic metabolism of fermentative and electroactive bacteria, which led to over 70% COD removal of the recalcitrant compounds and a record high H2 production rate (1.62 L L -1 d -1 ). We also employed the liquid-state 15N NMR on wastewater samples for the first time and revealed that the nitrogen-containing heteroaromatics were persistent to microbial electrochemical treatment. By integrating the chemical profiles with bioanode community profiles, we constructed a metabolic network that provides insights for enhancing treatment efficiency and facilitating resource recovery.
08 HYDROGEN↗
Bifunctionality of supported metal hydrodeoxygenation catalysts
The transition to sustainable energy relies on innovative methods to convert biomass-derived compounds into viable biofuels. In this study, the hydrodeoxygenation (HDO) of 6-undecanone is used as a model reaction to screen bifunctional catalysts, where metal sites facilitate hydrogenation and the support promotes deoxygenation, enabling high conversion and selectivity toward desirable alkanes for biofuel production. This reaction is particularly relevant as it represents a critical step in upgrading volatile fatty acids, derived from biomass, into long-chain hydrocarbons suitable for fuel applications. By examining a range of metals (nickel, cobalt, and tin) on different supports, it is revealed that the choice of metal–support combination is critical to catalyst performance. Zeolite beta's 3D microporous structure and adjustable acidity provide an ideal environment for fine-tuning metal–support interactions (MSIs), which are essential for balancing deoxygenation with alkane isomerization, a desirable trait for biofuels.
09 BIOMASS FUELS↗