The paper analyzes a possibility to involve hybrid thermonuclear reactors into the existing nuclear power systems. The possibility is related with production of non-traditional nuclear fuel in ...thorium blanket of hybrid thermonuclear reactors on D-T plasma. Non-traditional peculiarity of such a fuel consists in significant amounts of some non-traditional isotopes, namely231Pa and232U, together with traditional uranium isotope233U in the fuel. High-energy (14.1 MeV) thermonuclear neutrons can provide accumulation of significant231Pa and232U quantities through threshold (n,2n) and (n,3n) reactions. The promising features of the non-traditional fuel composition for nuclear power thermal reactors, basic component of the existing world-wide nuclear power industry, are defined by the following factors. As is known, 233U is able to provide more economical neutron balance in thermal reactors than235U and reactor-grade plutonium. The better neutron balance can result in higher values of the fuel breeding ratio and, as a consequence, in relaxation of the thermal reactors fuel self-sustainability problem. Isotopes231Pa and232U, being fertile and moderate fissionable nuclides, are able to stabilize time-dependent evolution of the thermal reactors power, prolong the thermal reactors lifetime through higher values of the fuel burn-up. Isotope232U, being intense α-emitter, is able to prevent any attempts for unauthorized usage of233U in nuclear explosive devices, i.e.232U can strengthen regime of nuclear non-proliferation. Thus, the hybrid thermonuclear reactors on D-T plasma with thorium blanket can be involved into nuclear power systems for generation of non-traditional, very promising fuel compositions for traditional nuclear power reactors.
Chemical reactions on the surface or throughout a thermoplastic fiber present an interesting and challenging reaction engineering problem. This paper presents the design and implementation of a ...modular multiphase continuous stirred tank reactor for the sulfonation of polyethylene fibers. Polyethylene fiber tows, composed of 1000–6000 filaments, are sulfonated in a series of stirred tank reactors. Fundamental reaction engineering principles are applied to address common batch-to-continuous reactor challenges, such as heat and mass transfer, material balances, and reaction kinetics. The introduction of polymer fibers to a continuous process also requires the solution of practical problems associated with fiber processing. Additional considerations are introduced for designing a reactor system for continuous processing of fiber using liquid with a batch reactor or CSTR contacting pattern in each vessel and containing the effluent gaseous reaction byproducts in a controlled vent stream. The overall sulfonation reaction stoichiometry was determined such that ≈1 mol of SO3 reacts per mol of CH2 fed. Additionally, carbon sulfonation selectivity was determined to be 95–99%, depending on the sulfonation conditions.
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•Hydrocracking and hydrotreating reactions kinetics based on lumping technique.•Hydrotreating reactions are also considered.•Axial dispersion model is used to represent the ...slurry-phase reactor.•Dynamic and steady-state simulations for hydrocracking of heavy oils are presented.•The performance of CSTR and SPR is compared.
The dynamic modeling and simulation of a continuous slurry phase reactor for catalytic hydrocracking and hydrotreating of an atmospheric residue (312 °C+) are reported. The reactor model is based on an axial dispersion. The hydrocracking kinetic model takes into account a five-lump model previously reported in the literature. The hydrotreating reactions simulated are: hydrodesulfurization (described by Langmuir–Hinshelwood kinetics), hydrodenitrogenation (for basic and non-basic nitrogen), hydrodeasphaltenization and hydro Conradson carbon removal (modeled with power-law approach). All the intrinsic kinetic parameters and correlations were taken from the literature. The performance for the slurry-phase reactor was compared with a continuous stirred tank reactor. Dynamic simulations and steady-state predictions agreed with the expected behavior of the heavy fractions and impurities hydroprocesing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A combination of photocatalysis and membrane separation technology is applied to the degradation of refractory antibiotic organic compounds in aqueous solutions. TiO2 photocatalysts, which are ...inexpensive, commercially available, and nontoxic, have lately been of wide concern. In this study, a submerged ceramic membrane photocatalytic reactor (SCMPR) coupling with a suspended TiO2 photocatalyst was designed and developed for removing antibiotics in environmental water remediation. Separation of the TiO2 photocatalyst was carried out via antifouling ceramic membranes with hollow structures. The SCMPR had high removal capacity and stability for amoxicillin (AMX) degradation over a wide pH range, i.e., 6.5 to 9.0. The unique hollow structure of the ceramic membranes and aeration system not only provided high self-purification capability, but also enhanced the removal stability, of the SCMPR. As a result, SCMPRs are promising wastewater processing devices for practical application. Two possible pathways for AMX photodegradation in the SCMPR were analyzed by means of a Q-TOF LC/MS system, with most of the intermediates finally mineralized to CO2, water, and inorganic ions by hydroxyl radicals.
•The SCMPR exhibited high mineralization capacity and stability for AMX degradation.•Ceramic membranes showed good corrosion and oxidation resistance.•The hollow structure of ceramic membrane provided high self-purification capability.•The TiO2 was separated effectively using the ceramic membrane separation technology.
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•56% of the energy contained in the agave bagasse was recovered by two-stage process.•Energy recovery from two-stage process was 7 times higher than one-stage process.•The increase of ...stirring speed decreased the H2-consumption by homoacetogenesis.•In the second-stage, methane yields of 90% were obtained at high OLR and short HRT.
Continuous H2 and CH4 production in a two-stage process to increase energy recovery from agave bagasse enzymatic-hydrolysate was studied. In the first stage, the effect of organic loading rate (OLR) and stirring speed on volumetric hydrogen production rate (VHPR) was evaluated in a continuous stirred tank reactor (CSTR); by controlling the homoacetogenesis with the agitation speed and maintaining an OLR of 44 g COD/L-d, it was possible to reach a VHPR of 6 L H2/L-d, equivalent to 1.34 kJ/g bagasse. In the second stage, the effluent from CSTR was used as substrate to feed a UASB reactor for CH4 production. Volumetric methane production rate (VMPR) of 6.4 L CH4/L-d was achieved with a high OLR (20 g COD/L-d) and short hydraulic retention time (HRT, 14 h), producing 225 mL CH4/g-bagasse equivalent to 7.88 kJ/g bagasse. The two-stage continuous process significantly increased energy conversion efficiency (56%) compared to one-stage hydrogen production (8.2%).
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•An innovative fixed-film anaerobic reactor was applied to sugarcane vinasse.•Stable operation was observed for OLRs as high as 30kg COD m−3day−1.•Propionate buildup did not impact ...the stability of the structured-bed reactor.•Enhanced bioenergy recovery was estimated from biodigestion with phase separation.•Energy extraction was over 20% higher compared to single-phase systems.
This study considered the application of anaerobic digestion (AD) with phase separation combined with the use of an anaerobic structured-bed reactor (ASTBR) as the methanogenic phase for the treatment of sugarcane vinasse, a high-strength wastewater resulting from ethanol production. Two combined thermophilic acidogenic-methanogenic systems formed by one single acidogenic reactor followed by two methanogenic reactors operated in parallel were compared, namely, a conventional UASB reactor and an upflow ASTBR reactor. Increasing organic loading rate (OLR) conditions (15–30kgCODm−3d−1) were applied to the methanogenic reactors. The results highlighted the feasibility of applying the ASTBR to vinasse, indicating a global COD removal higher than 80%. The ASTBR exhibited a stable long-term operation (240days), even for OLR values as high as 30kgCODm−3d−1. The application of similar conditions to the UASB reactor indicated severe performance losses, leading to the accumulation of acids for every increase in the OLR. An energetic potential of 181.5MJ for each cubic meter of vinasse was estimated from both hydrogen and methane. The provision of bicarbonate alkalinity proved to be a key factor in obtaining stable performance, offsetting the limitations of relatively low hydraulic retention times (<24h).
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•Semi-continuous biological/electrochemical process mineralize organics from slaughterhouse wastewater.•90% of COD decay by anaerobic digestion produces more than 0.35 L Lreactor−1 d−1 of ...methane.•The effluent of UASB was treated by SPEF process reaching almost total mineralization.•The semi-continuous process produces colorless and odorless water.•The combined processes reduce costs for the treatment of slaughterhouse wastewater.
A new semicontinuous anaerobic digestion/solar photoelectro-Fenton (SPEF) process for the treatment of slaughterhouse wastewater is studied. An Upflow Anaerobic Sludge Blanket (UASB) reactor was used at two different organic load rates (OLR) (3.94 and 8.15 g COD L−1 d−1), while the SPEF was carried out in a photoelectrochemical reactor using a filter press cell with a DSA anode and an air diffusion cathode. The results showed that the UASB reactor achieved up to 70% COD removal for the highest OLR, with a low efficiency of suspended solid removal. The anaerobic effluent was treated by the SPEF process, resulting in 88% and 72% COD removal for the initial concentrations of 195 ± 14 mg L−1 and 867 ± 52 mg L−1, respectively, and a turbidity reduction of up to 80%. The treatment of wastewater by SPEF using a current density of 10 mA cm−2 was five times less costly than that of 25 mA cm−2, with an associated cost of 1.4 USD h−1 for the treatment. The proposed semicontinuous processes eliminate at least 91% of the total COD, thus representing a new option for the treatment of slaughterhouse wastewater.
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The environmentally-friendly, economically-viable production of ethanol from cellulosic biomass remains a major contemporary challenge. Much work has been done on the disruption of cellulosic biomass ...structure, the production of enzymes for the conversion of cellulose and hemicellulose into simple sugars that can be fermented by bacteria or yeast, and the metabolic engineering of ethanol-producing microbes. The results of these studies have enabled the transition from laboratory to industrial scale of cellulosic ethanol production. Notably, however, current processes use free microbial cells in batch reactors. This review highlights the advantages of using immobilized and co-immobilized cells together with continuous bioreactor configurations. These developments have the potential to improve both the yield and the green credentials of cellulosic ethanol production in modern industrial settings.
•Cellulosic ethanol production needs application of new technologies for competing with gasoline.•Cell immobilization technologies improve bioethanol productivity.•Ethanol yield in different processes is affected by the reactor configurations.
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•CuO NPs in 1mgL−1 performed most severe suppression on Anammox.•TiO2 NPs in 1mgL−1 showed most durable inhibition on Anammox.•Long-term exposure within NPs led to the increase of microbial ...diversity.•Long-term exposure within NPs resulted in abundance decrease of AAOB.•Candidatus Brocadia showed more tolerance to NPs than Candidatus Kuenenia.
In this study, a sequencing batch reactor (SBR) was operated as Anammox and used as parent reactor. Then three SBRs seeded from the parent reactor were adopted for investigating the effect of CuO, ZnO and TiO2 nanoparticles (NPs) on nitrogen removal, microbial activity and microbial communities of Anammox. The bioactivities of anaerobic ammonia-oxidizing bacteria (AAOB) after different exposure period were detected by batch experiments. Results showed that NPs performed immediate and durable toxicity on Anammox. The nitrogen removal efficiency decreased to 2.3%, 2.9% and 14.0% from 71%, the Anammox rate decreased to 0.13, 0.16 and 0.75 from 2.76mgh−1g−1VSS, and the relative abundance of AAOB decreased to 2.57%, 2.78% and 2.61% from 7.99%, respectively. CuO and ZnO NPs performed similar effect, while CuO NPs led to the most severe toxicity and lowest accumulative effect. TiO2 NPs showed the lowest toxicity but most durable suppression on Anammox process.
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•A mechanism that drives a successful and fast bioaugmentation process is proposed.•Hydrogenotrophic methanogens are crucial for an efficient bioaugmentation process.•Successful ...bioaugmentation was achieved in ammonia-inhibited thermophilic reactors.•Bioaugmentation with hydrogenotrophic methanogen stimulated the growth of SAOB.•The VFA-ammonia co-inhibitory effect decreased rapidly after bioaugmentation.
Bioaugmentation to alleviate ammonia inhibition under thermophilic anaerobic digestion has never been reported, as well as the working mechanism that allows a fast and successful bioaugmentation. Thus two bioaugmentation inocula (an enriched culture, and a mixed culture composed 50/50 by Methanoculleus thermophilus and the enriched culture) on the recovery of ammonia-inhibited thermophilic continuous reactors was assessed. The results showed that bioaugmentation improved methane yield by 11–13% and decreased the volatile fatty acids (VFA) by 45–52% compared to the control reactor (abiotic augmentation). Moreover, the importance of hydrogenotrophic methanogens to a fast and successful bioaugmentation was recognized. Specifically, the instant hydrogen partial pressure reduction by the bioaugmented hydrogenotroph created thermodynamically favourable conditions for the acetate oxidation process and consequently, the catabolism of other VFA. High-throughput sequencing results strengthened this explanation by showing that the bioaugmented M. thermophilus stimulated the growth of syntrophic acetate oxidising bacterium Thermacetogenium phaeum, immediately after bioaugmentation.
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