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Hydrothermal liquefaction (HTL) is regarded as a promising technology for the production of biofuels from biomass and wastes. As such, there is a drive towards continuous-flow processing systems to aid process scale-up and eventually commercialization. The current study presents results from a novel pilot-scale HTL reactor with a feed capacity of up to 100 L/h and a process volume of approximately 20 L. The pilot plant employs a heat exchanger for heat recovery and a novel hydraulic oscillation system to increase the turbulence in the tubular reactor. The energy grass Miscanthus and the microalgae Spirulina, both representing advanced dedicated energy crops, as well as sewage sludge as high-potential waste stream were selected to assess the reactor performance. Biomass slurries with up to 16 wt% dry matter content were successfully processed. The heat recovery of the heat exchanger is found to increase with reactor run time, reaching 80% within 5–6 h of operation. The hydraulic oscillation system is shown to improve mixing and enhance heat transfer. Bio-crudes with average yields of 26 wt%, 33 wt% and 25 wt% were produced from Miscanthus, Spirulina and sewage sludge, respectively. The yields also appeared to increase with reactor run time. Bio-crude from HTL of Spirulina was mainly composed of palmitic acid, glycerol, heptadecane and linolelaidic acid, while biocrude from sewage sludge contained mainly palmitic acid, oleic acid and stearic acid. In contrast, biocrude from HTL of Miscanthus consisted of a large number of different phenolics. An energetic comparison between the three feedstocks revealed a thermal efficiency of 47%, 47% and 33% and energy return on investment (EROI) of 2.8, 3.3 and 0.5 for HTL of Miscanthus, Spirulina and sewage sludge, respectively.

Biodiesel from waste oil is produced using heterogeneous catalyzed transesterification in a fixed bed reactor (FBR). Potassium iodide/calcium oxide/alumina (KI/CaO/Al2O3) catalyst was prepared through the processes of calcination and impregnation. The novel catalyst was analyzed with X‐ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X‐ray spectrometer (EDX). The design of experiment (DoE) method resulted in a total of 20 experimental runs. The significance of 3 reaction parameters, namely catalyst bed height, methanol to waste oil molar ratio, and residence time, and their combined impact on biodiesel yield is investigated. Both the artificial neural network (ANN) based on artificial intelligence (AI) and the Box‐Behnken design (BBD) based on response surface methodology (RSM) were utilized in order to optimize the process conditions and maximize the biodiesel production. A quadratic regression model was developed to predict biodiesel yield, with a correlation coefficient (R) value of 0.9994 for ANN model and a coefficient of determination (R2) value of 0.9986 for BBD model. The maximum amount of biodiesel that can be produced is 98.88 % when catalyst bed height is 7.87 cm, molar ratio of methanol to waste oil is 17.47 : 1, and residence time is 3.12 h. The results of this study indicate that ANN and BBD models can effectively be used to optimize and synthesize the highest %yield of biodiesel in a FBR. The production of biodiesel involves the transesterification of waste oil in a fixed bed reactor using a catalyst composed of potassium iodide, calcium oxide, and alumina. Predicting and validating optimal conditions for biodiesel production is accomplished using artificial neural network (ANN) and response surface methodology (RSM). The ANN and RSM are effective tools for statistical modeling of biofuel manufacturing processes.

This work performed co-AD from the vinasse and filter cake (from 1G ethanol production) and deacetylation liquor (from the pretreatment of sugarcane straw for 2G ethanol production) in a semi-Continuous Stirred Tank Reactor (s-CSTR) aiming to provide optimum operational parameters for continuous CH4 production. Using filter cake as co-substrate may allow the reactor to operate throughout the year, as it is available in the sugarcane off-season, unlike vinasse. A comparison was made from the microbial community of the seed sludge and the reactor sludge when CH4 production stabilized. Lactate, butyrate, and propionate fermentation routes were denoted at the start-up of the s-CSTR, characterizing the acidogenic phase: the oxidation-reduction potential (ORP) values ranged from −800 to −100 mV. Once the methanogenesis was initiated, alkalizing addition was no longer needed as its demand by the microorganisms was supplied by the alkali characteristics of the deacetylation liquor. The gradual increase of the applied organic load rates (OLR) allowed stabilization of the methanogenesis from 3.20 gVS L−1 day−1: the highest CH4 yield (230 mLNCH4 g−1VS) and average organic matter removal efficiency (83% ± 13) was achieved at ORL of 4.16 gVS L−1 day−1. The microbial community changed along with the reactor operation, presenting different metabolic routes mainly due to the used lignocellulosic substrates. Bacteria from the syntrophic acetate oxidation (SAO) process coupled to hydrogenotrophic methanogenesis were predominant (~ 90% Methanoculleus) during the CH4 production stability. The overall results are useful as preliminary drivers in terms of visualizing the co-AD process in a sugarcane biorefinery integrated to scale.Key points• Integration of 1G2G sugarcane ethanol biorefinery from co-digestion of its residues.• Biogas production from vinasse, filter cake, and deacetylation liquor in a semi-CSTR.• Lignocellulosic substrates affected the biochemical routes and microbial community.• Biomol confirmed the establishment of the thermophilic community from mesophilic sludge.

The demand for lithium is expected to increase significantly in the next few years, mainly due to the energy transition in the mobility sector. To electrify the entire global transportation system, it is necessary to have access to a wide variety of lithium deposits to ensure resource sovereignty and sufficient supply to meet demand. For this reason, much effort has recently been invested in developing technologies for direct lithium extraction (DLE) from brines. In this work, a membrane‐based continuous flow‐by reactor for the electrochemical extraction of lithium from brine with a LiMn2O4/λ‐MnO2 system has been studied. A zoned reactor was proposed in which the current density and electrode mass loading gradually decrease along with the depletion of lithium in the brine, obtaining an average electrode capacity of 80 mAh/g throughout three different reactor sections. The limiting Reynolds number was determined for the dilute lithium segment of the reactor to avoid mass transport limitations, with brine concentration equal to Li 3 mM and Na 1.3 M. A homogeneous cycle time was achieved for the three reactor zones and their associated average energy consumption was determined, ranging from 3.9 Wh/mol Li to 9.5 Wh/mol Li. A three‐zone electrochemical reactor for direct lithium extraction from brines with a membrane‐based LiMn2O4/λ‐MnO2 ion pumping system has been studied. The inter‐relationship between reactor configuration, brine hydrodynamic regime, electrode mass loading, current density and electrolyte concentration was analyzed considering system optimization aspects.

Biocatalysis has widened its scope and relevance since new molecular tools, including improved expression systems for proteins, protein and metabolic engineering, and rational techniques for immobilization, have become available. However, applications are still sometimes hampered by low productivity and difficulties in scaling up. A practical and reasonable step to improve the performances of biocatalysts (including both enzymes and whole-cell systems) is to use them in flow reactors. This review describes the state of the art on the design and use of biocatalysis in flow reactors. The encouraging successes of this enabling technology are critically discussed, highlighting new opportunities, problems to be solved and technological advances. Biocatalyzed reactions with different classes of enzymes can be implemented with the integration of flow reactor technology, potentially leading to sustainable and highly productive continuous processes. The combination of biocatalysis and flow chemistry opens the door to extensive application in cascade reactions. Biocatalyzed flow reactions can occur either in monophasic flow or in segmented (slug) flow, where two or more immiscible phases are present. Limitation of substrate/product inhibition effects, in-line purification with easy recovery of the product, and no mechanical mixing are among the most distinctive advantages of flow-based biocatalysis. Automated machines and devices for in-line product recovery are now available at relatively low prices, making flow-based biocatalysis an easy-to-use technology.

A double-helical photocatalytic module was fabricated via an annealing process following an anodic oxidation procedure, and installed into a commercial UV sterilizer to structure continuous-flow photocatalytic device. Benefiting from the superior mass transfer of double-helical structure to common flat plate or corrugated plate, as well as the improved adhesion between Ti support and TiO₂ layer, the photocatalytic device displayed potential in practical disinfection and degradation of organics. During photocatalytic disinfection process with 21 mJ/cm² of UV dose, the concentration of Escherichia coli decreased from 1.71 × 10⁷ CFU/L (typical for municipal wastewater) in influent to 2,720 CFU/L in effluent water, which met the wastewater discharged standard of China. Escherichia coli reactivation ratio for the photocatalytic device was only one-tenth of that for UV sterilizer. Furthermore, taking phenol, bisphenol A, and four antibiotics as targets, the device was demonstrated to promote the degradation of photodegradable pollutants via photocatalysis. These results highlight a feasibility of photocatalytic technology as a supporting role in practical wastewater treatment.

Three distinct sol-gel synthesis methodologies were employed to fabricate niobium catalysts supported on stainless steel meshes via the dip-coating technique, with the objective of their utilization in layered configurations for water purification applications. The structured catalysts were subjected to calcination at three varying temperatures: no calcination, calcination at 823 K, and calcination at 1173 K. Ibuprofen, selected as the model pollutant due to its emerging contaminant profile, was utilized for evaluation. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) images, in conjunction with adhesion assessments, elucidated that thermally treated catalysts exhibited nearly 80% retention of Nb 2 O 5 nanoparticles adhered uniformly to the support surface. In batch reactor experiments, the catalyst derived from the NbCl 5 precursor and polyacrylonitrile (PAN) exhibited the most promising performance, achieving a 90% degradation of the contaminant within a 120 min timeframe. This catalyst, exhibiting superior efficacy, was subsequently employed in tests utilizing photocatalytic bench reactors, where it demonstrated analogous performance to that observed in the batch reactor setup. Upon upscaling to a high-capacity photocatalytic prototype, the degradation efficiency was sustained above that observed in photolytic testing, even after four utilization cycles.

Understanding the residence time distribution (RTD) of a continuous hydrothermal reactor is of great significance to improve product quality and reaction efficiency. In this work, an on-line measurement system is attached to a continuous reactor to investigate the characteristics of RTD. An approach that can accurately fit and describe the experimental measured RTD curve by finding characteristic values is proposed for analysis and comparison. The RTD curves of three experiment groups are measured and the characteristic values are calculated. Results show that increasing total flow rate and extending effective reactor length have inverse effect on average residence time, but they both cause the reactor to approach a plug flow reactor and improve the materials leading. The branch flow rate fraction has no significant effect on RTD characteristics in the scope of the present work except the weak negative correlation with the average residence time. Besides, the natural convection stirring effect can also increase the average residence time, especially when the forced flow is weak. The analysis reveals that it is necessary to consider the matching of natural convection, forced flow and reactor size to control RTD when designing the hydrothermal reactor and working conditions.

Mining activities produce acid mine drainage that can be treated with microorganisms, and in this case, sulfate reducing bacteria. Iron and manganese effect on the sulfate reduction process can be investigated using anaerobic batch and continuous reactors with various iron and manganese concentrations. For batch reactors, the highest efficiency of sulfate reduction and sulfate reduction rate was obtained by 0 mg Mn/l reactor. Both efficiency and rate continued to decline with the increasing of iron and manganese concentration. The temperature for all reactors remained stable. The sediment color in 0 mg Fe/l and 0 mg Mn/l reactors were remain black, while the sediment color in the rest of the reactors changed from black to brown. The COD concentration for all the reactors decreased and the highest efficiency was 35,50% which was obtained by 0 mg Fe/l reactors. The highest efficiency of iron reduction was 99,23% and was achieved by 60 mg Fe Mn/l reactor. The effect for continuous and batch reactors are quite identical.