Reactor System Research Articles

Removal of Ampicillin with Nitrifying Cultures in a SBR Reactor.

The presence of antibiotics in wastewater discharges significantly affects the environment, mainly due to the generation of bacterial populations with multiple antibiotic resistances. The cometabolic capacity of nitrifying sludge to simultaneously remove ammonium (NH4+) and emerging organic contaminants (EOCs), including antibiotics, has been reported. In the present study, the removal capacity of 50mg ampicillin (AMP)/L by nitrifying cultures associated with biosorption and biotransformation processes was evaluated in a sequencing batch reactor (SBR) system. The contribution of nitrifying enzymes (ammonium monooxygenase (AMO) and nitrite oxidoreductase (NOR)) and β-lactamases in AMP biodegradation was evaluated using specific inhibitors in batch cultures. AMP was 100% eliminated after 5h since the first cycle of operation. The sludge maintained its ammonium oxidizing capacity with the total consumption of 102.0 ± 2.5mg NH4+-N/L in 9h, however, the addition of AMP altered the nitrite-oxidizing process of nitrification, recovering 30 cycles later at both physiological and kinetic level. The kinetic activity of the nitrifying sludge improved along the operating cycles for both AMP removal and nitrification processes. The elimination of 24% AMP was attributed to the biosorption process and 76% to biotransformation, wherein the AMO enzyme contributed 95% to its biodegradation. Finally, the repeated exposure of the sludge to AMP for 72 operating cycles (36days) was not sufficient to detect β-lactamase activity. The cometabolic ability of ammonium-oxidizing bacteria for biodegrading AMP could be employed for bioremediation of wastewater.

Acidobacteria as the dominant microorganism on the nitrogen-removal wastewater treatment with a low chemical oxygen demand/ammonium nitrogen ratio in biological contact oxidation reactor.

Nitrogen-removal promotion is a significant problem when biological nitrogen removal is used to treat ammonium nitrogen (NH4+-N) wastewater with a low chemical oxygen demand (COD)/NH4+-N (C/N) ratio. In this work, the biological nitrogen removal capacity of the biological contact oxidation reactor (BCOR) system was enhanced through the enrichment of Acidobacteria. The system was successfully started from Day 1 to Day 50 and stably operated through temperature, pH, and dissolved oxygen (DO) regulation from Day 51 to Day 254. The average ammonium nitrogen-removal efficiency over the performance period was 96.2%, whereas the average total nitrogen-removal efficiency was 86.9%, according to the data. In the meantime, the predominant microbes in the BCOR system were initially found to belong to the phylum Acidobacteria (relative abundance of 48.39%). Additionally, it was found for the first time in this system that three different genera of unnamed microorganisms (two of which belonged to the phylum Acidobacteria and one to the phylum Chlorobi), the relative abundances of which were 30.46%, 11.45% and 16.00%, respectively. Candidatus Xiphinematobacter (belonging to the phylum Verrucomicrobia, relative abundances of 8.81%), and Pseudomonas (belonging to the phylum Proteobacteria, relative abundances of 5.59%). This new finding will be very beneficial for future research into the microbiological mechanisms and technological engineering applications of the BCOR system for treating ammonium nitrogen wastewater with a low C/N ratio.

A Cross-Layer Game-Theoretic Approach to Resilient Control of Networked Switched Systems Against DoS Attacks.

This article investigates the resilient control strategies of networked switched systems (NSSs) against denial-of-service (DoS) attacks and external disturbance. In the network layer, both the defender and the attacker allocate energy over multiple channels. Considering the impact of switching characteristic in the physical layer on the network layer, a dynamic regulating factor is proposed to adjust the total energy of the defender. To optimize the signal-to-interference-noise ratio and energy consumption simultaneously at each player's side, a multiobjective game problem is formulated. Furthermore, a nondominated sorting genetic algorithm framework is employed, incorporating the knee point selection mechanism to attain the Pareto-Nash equilibrium, based on which the optimal defense strategy can be derived to achieve resilience against DoS attacks. In the physical-layer, taking the dynamic packet loss caused by DoS attacks and external disturbance into account, an H∞ minimax controller containing control inputs and the switching signal is designed to guarantee the optimal performance for NSSs through the dynamic game-theoretic approach. Finally, the networked continuous stirred tank reactor system is provided to verify the effectiveness of the proposed method.

Electrochemical valorization of captured CO2: recent advances and future perspectives.

The excessive emission of CO2 has led to severe climate change, prompting global concern. Capturing CO2 and converting it through electrochemistry into value-added products represent promising approaches to mitigating CO2 emissions and closing the carbon cycle. Traditionally, these two processes have been performed independently, involving multiple steps, high energy consumption, and low efficiency. Recently, the electrochemical conversion of captured CO2, which integrates the capture and conversion processes (also referred to as electrochemically reactive CO2 capture), has garnered increasing attention. This integrated approach bypasses the energy-intensive steps involved in the traditional independent process, including CO2 release, purification, compression, transportation, and storage. In this review, we discuss recent advances in the electrochemical conversion of captured CO2, focusing on four key aspects. First, we introduce various capture media, emphasizing the thermodynamic aspects of carbon capture and their implications for integration with electrochemical conversion. Second, we discuss product control mediated by the selection of different catalysts, highlighting the connections between the conversion of captured CO2 and gas-fed CO2. Third, we examine the effect of reactor systems and operational conditions on the electrochemical conversion of captured CO2, shedding light on performance optimization. Finally, we explore real integration systems for CO2 capture and electrochemical conversion, revealing the potential of this new technology for practical applications. Overall, we provide insights into the existing challenges, potential solutions, and thoughts on opportunities and future directions in the emerging field of electrochemical conversion of captured CO2.

Effect of Polymer Variation as Carrier Media for Microorganism Growth in Biofilm Development using Aerobic Fixed-Biofilm Reactor System

Effect of Polymer Variation as Carrier Media for Microorganism Growth in Biofilm Development using Aerobic Fixed-Biofilm Reactor System

Continuous-flow synthesis of carboxylic acids from alcohols via platinum and silicon dioxide-catalyzed hydrogen peroxide oxidation.

A continuous-flow method for the direct oxidation of alcohols to carboxylic acids is reported, employing hydrogen peroxide (H2O2) and a platinum (Pt) catalyst within a flow reactor system. This approach allows for precise control over the contact time between the reactants and the catalyst, enabling optimization of reaction conditions. By analyzing the yields of both aldehydes and carboxylic acids as a function of weight hourly space velocity (WHSV), selective synthesis of carboxylic acids was achieved without the formation of corresponding aldehydes. The Pt catalyst exhibited excellent stability, producing 25.2 g of octanoic acid from 1-octanol with a yield exceeding 96% over 210 h at a WHSV of 1.3 h-1 using a 5 mm inner diameter × 100 mm column. This Pt-catalyzed continuous-flow H2O2 oxidation method demonstrates good reactivity for a variety of alcohols, including aliphatic, aromatic, allylic, and heteroaromatic, affording the corresponding carboxylic acids in 19-98% isolated yields with water as the sole byproduct. X-ray photoelectron spectroscopy (XPS) analysis confirmed the preservation of metallic zero-valent Pt (Pt(0)) throughout the reaction.

Minimizing Energy Usage in the Production of Benzene through Hydrodealkylation Toluene Process by Optimizing Heat Transfer Unit in Reactor System

Benzene is a chemical raw material that is widely used without alternatives in the production of high energy solid liquid fuels and polymers. As a result, the global demand of benzene reaches 51 million per year. The process simulator has been utilized to simulate the reactor system of benzene production through the hydrodealkylation of toluene using Peng-Robinson equation-of-state property package. This system is designed to reach 200,000 tons of benzene per year with an optimized heat flow mechanism. By using a heat recovery strategy that utilizes the heat stream outlet from the waste heat boiler (WHB-01) and the partial condenser (PC-01), the net-energy in the simulation has been effectively minimized by saving a total of -23,915,490.40 kJ/h by directing the heat streams to heaters H-01 and H-02, respectively. Considering this strategy, the modified process within the reactor system is conclusively more optimized than the basic process system. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Аварія на Ленінградській АЕС (1975) у контексті передумов Чорнобиля

The purpose of the study is to reconstruct and analyze a set of issues related to the accident at the Leningrad NPP in the context of clarifying the prerequisites of the Chernobyl disaster. Our study examines issues related to the accident at Unit 1 of the Leningrad NPP (LNPP) in 1975. This is the largest accident in the «pre-Chernobyl» period, a precursor to Chernobyl. This topic remains ignored in domestic historical scientific literature. The article by the co-authors, based on published sources, mostly memoirs, attempts to highlight a number of aspects related to the accident at the Leningrad NPP. The research methodology is based on a combination of general scientific (analysis, synthesis, generalization) and special historical (historical-genetic, historical-typological, historical-comparative) methods with the principles of historicism, systematicity, scientificity and verification. The scientific novelty of the work lies in the fact that the development of aspects related to the problems of the history of nuclear energy in the USSR is almost not studied in domestic historical science. In this regard, in particular, the study of the prehistory and prerequisites of the Chernobyl disaster is important. Conclusions. It was established that the design of the RBMK-1000 reactor and other technological systems of the power unit were far from perfect. It has been established that the design of the RBMK-1000 reactor and other technological systems of the power unit were far from perfect. It is shown that the process of improving the reactor installation took place during installation and operation, including through various experiments. The available sources to a certain extent make it possible to reconstruct the causes, prerequisites, nature and circumstances of this accident. First of all, it is found that the accident revealed serious shortcomings of the RBMK-1000 reactor. The article highlights the socio-economic and human factors of the accident. In particular, it is shown that at Soviet nuclear power plants the policy of prioritizing the plan for generating electricity over the requirements of regulatory documents for the safe operation of the reactor dominated. A similar phenomenon occurred at the Chernobyl Nuclear Power Plant (ChNPP). Based on the sources, it was possible to clarify the key role in creating the accident of a certain person, namely the senior reactor control engineer Mikhail Karrask. Our study also pays attention to covering the work of the special commission to investigate the accident. In this regard, it was particularly important to understand whether information about the nature of the accident and the commission's recommendations on improving the operation of the RBMK-1000 reactor reached the attention of the personnel of other nuclear power plants, primarily the Chernobyl NPP.

The Effectiveness of an Anoxic-Oxic-Anoxic-Oxic Sequencing Batch Reactor System (A2/O2-SBR) to Treat Electroplating Wastewater and the Bacterial Community within the System

This study presents an examination of the effectiveness of an anoxic-oxic-anoxic-oxic sequencing batch reactor (A2/O2-SBR) for treating electroplating wastewater (EPWW). The A2/O2-SBR was monitored for 60 days and the bacterial composition in the treatment system was determined. The system consisted of four reactors, which had the following anoxic/oxic ratios: reactor-I, 0:9 h; reactor-II, 2:7 h; reactor-III, 4.5:4.5 h; and reactor-IV, 7:2 h. The combined cycle time of the reactors was 12 h, the hydraulic retention time (HRT) was five days, and the total volume of mixed liquor suspended solids (MLSS) was 2,000 mg/L. The results demonstrate the importance of an anoxic period for the treatment of heavy metals. Most of the ammonium nitrogen (NH4+-N), Total Kjeldahl nitrogen (TKN), and total nitrogen (TN) were removed during the oxic period. However, as the anoxic period increased, the amounts of TKN, nitrite nitrogen (NO2--N), nitrate nitrogen (NO3--N), and TN declined. Reactor-IV showed a high removal efficiency for heavy metals (Zn2+, 89.74%; Cd2+, 81.37%), TKN (89.20%), and TN (84.25%), and also effectively treated NH4+-N (78.84%), biochemical oxygen demand (BOD5; 93.5%), and chemical oxygen demand (COD; 84.9%). Reactor-IV showed an appropriate difference in the dissolved oxygen (DO) concentration between the anoxic period and oxic period (2.12-2.00 mg/L). The main bacterial phyla in the treatment system were Proteobacteria, Actinobacteria, and Firmicutes, while Pseudomonas vancouverensis and Cryobacterium arcticum were the most common species. The anoxic period and bacterial community have significantly demonstrated the ability to remove Zn2+ and Cd2+ for effective treatment of EPWW.

Changes in physico-chemical and functional properties of liquid egg white by ohmic heating process

In the present study, ohmic heating system was developed for the pasteurization of liquid egg white. A batch reactor system was designed with a capacity of 100 ml and operated at varied gradients of voltage (20, 15, 10 V/cm), frequencies (10, 55, 100 Hz), holding times (1, 2.5, 4 min) at two different waveforms (sine and square). The treated liquid egg white was evaluated for validation parameters viz., heating rate, turbidity, soluble protein content, foaming capacity, and foaming stability. The viscosity of ohmically treated egg white was observed by subjecting the egg white to the shear rate ranges from 0.167 to 68 (s−1) where the viscosity decreased as the shear rate increased. The ohmic heating process variables were optimized using the Box-Behnken design and had a significant effect (P < 0.005) on the responses. The optimized parameters 17.93 V/cm voltage gradient, 10 Hz frequency, and 1.6 min holding time for sine waveform resulted in 19.6 °C/min heating rate, 0.01 turbidity, 98.35% soluble protein, 405.68% foaming capacity, and 31.84% foaming stability with the highest desirability of 78% of liquid egg white. The model developed from the dataset of this design can be used for predicting the responses within the limits of process variables.

Preparing Al2O3/TiO2 nano-multilayers on the surface of FeAl/Al2O3 coating as tritium permeation barrier

Abstract Preparing tritium permeation barrier (TPB) coating on the surface of structural materials can effectively alleviate tritium permeation in fusion reactor system. However, due to the existence of inevitable certain number of defects in TPB, there is still a gap between the commonly prepared TPB coatings and the requirements proposed by fusion reactors. In this work, composite coatings with Al2O3/TiO2 nano-multilayers (NMLs) covering on the surface of FeAl/Al2O3 coating were prepared as TPB. The FeAl/Al2O3 TPB coating on the surface of 316L stainless steel was prepared by electrochemical deposition of Al, aluminization and in-situ oxidation. Due to the aggregation of Cr, there are micro sized defects in the Al2O3 layer. The presence of defects seriously reduces its hydrogen isotopes permeation resistance. The atomic layer deposition was then adopted to prepare Al2O3/TiO2 NMLs with period thickness of 15, 7.5 and 3 nm on the surface of Al2O3 layer, which not only cover the defects, but also utilize interfaces to suppress hydrogen isotopes permeation. The composite coating sample with the period thickness of 3 nm showed great enhancement of two orders of magnitude in deuterium permeation resistance property compared to the original FeAl/Al2O3 TPB coating at 500 °C, and the permeation reduction factor reaches a high value of 5 × 105, which far above the requirements of future fusion reactors.

Continuous Flow Photoelectrochemical Reactor with Gas Permeable Photocathode: Enhanced Photocurrent and Partial Current Density for CO2 Reduction.

Photoelectrochemical (PEC) CO2 reduction using a photocathode is an attractive method for making valuable chemical products due to its simplicity and lower overpotential requirements. However, previous PEC processes have often been diffusion-limited leading to low production rates of the CO2 reduction reaction, due to inefficient gas diffusion through the liquid electrolyte to the catalyst surface, particularly at high current densities. In this study, a gas-permeable photocathode in a continuous flow PEC reactor is incorporated, which facilitates the direct supply of CO2 gas to the photocathode-electrolyte interface, unlike dark reaction-based flow reactors. This concept is demonstrated using Ag-TiO2 on carbon paper, illuminated through a quartz window and flowing liquid electrolyte. CO2 supply is managed via pressure and flow control on the non-illuminated side of the carbon paper. The photocurrent density is significantly influenced by the flow rates and pressure of CO2 gas, and the electrolyte flow rates. Compared to the traditional H-cell, the continuous PEC flow reactor achieves ≈10-fold increase in CO faradaic efficiency, 30-fold increase in production rate and 16-fold increase in stability without catalyst modifications. This work provides essential insights into the design and application of continuous gas-liquid flow PEC reactor systems, highlighting their potential for other PEC reactions.

Droplet Entrainment in Steam Supply System of Water-Cooled Small Modular Reactors: Experiment and Modeling Approaches

Droplet Entrainment in Steam Supply System of Water-Cooled Small Modular Reactors: Experiment and Modeling Approaches

Controlling the Reaction Pathways of Mixed NOxHy Reactants in Plasma-Electrochemical Ammonia Synthesis.

Electrochemical activation of dinitrogen (N2) is notoriously challenging, typically yielding very low ammonia (NH3) production rates. In this study, we present a continuous flow plasma-electrochemical reactor system for the direct conversion of nitrogen from air into ammonia. In our system, nitrogen molecules are first converted into a mixture of NOx species in the plasma reactor, which are then fed into an electrochemical reactor. To selectively convert the generated NOx species into NH3, we employed a graph theory approach combined with first-principles calculations to comprehensively enumerate all possible pathways from N2-to-NH3, pinpointing key intermediates (NH2* and NO*). A series of bimetallic catalysts was then designed to target the optimal adsorption and conversion of the limiting intermediate in the NOx-to-NH3 pathway. Using an optimized CuPd foam catalyst, we demonstrated an ammonia production rate of 81.2 mg h-1 cm-2 with stability over 1000 h at an applied current of 2 A.

Measurement and analysis of the 246Cm and 248Cm neutron capture cross-sections at the EAR2 of the n_TOF facility at CERN

The 246Cm(n,γ) and 248Cm(n,γ) cross-sections have been measured at the Experimental Area 2 (EAR2) of the n_TOF facility at CERN with three C6D6 detectors. This measurement is part of a collective effort to improve the capture cross-section data for Minor Actinides (MAs), which are required to estimate the production and transmutation rates of these isotopes in light water reactors and innovative reactor systems. In particular, the neutron capture in 246Cm and 248Cm open the path for the formation of other Cm isotopes and heavier elements such as Bk and Cf and the knowledge of (n,γ) cross-sections of these Cm isotopes plays an important role in the transport, transmutation and storage of the spent nuclear fuel. The reactions 246Cm(n,γ) and 248Cm(n,γ) have been the two first capture measurements analyzed at n_TOF EAR2. Until this experiment and two recent measurements performed at J-PARC, there was only one set of data of the capture cross-sections of 246Cm and 248Cm, that was obtained in 1969 in an underground nuclear explosion experiment. In the measurement at n_TOF a total of 13 resonances of 246Cm between 4 and 400 eV and 5 of 248Cm between 7 and 100 eV have been identified and fitted. The radiative kernels obtained for 246Cm are compatible with JENDL-5, but some of them are not with JENDL-4, which has been adopted by JEFF-3.3 and ENDF/B-VIII.0. The radiative kernels obtained for the first three 248Cm resonances are compatible with JENDL-5, however, the other two are not compatible with any other evaluation and are 20 and 60% larger than JENDL-5.

Deep-Learning and Dynamic Time Warping-Based Approaches for the Diagnosis of Reactor Systems.

The degradation of clamping force in the core support barrel, which forms the internal structure of a nuclear power plant, has the potential to significantly impact the plant's safety and reliability. Previous studies have concentrated on the detection of clamping force degradation but have been constrained in their ability to identify the precise size and position. This study proposes a novel methodology for diagnosing the size and position of clamping force degradation in core support barrels, combining deep-learning techniques and dynamic time warping (DTW) algorithms. DTW is applied to the magnitude data of the ex-core neutron noise signal obtained in the frequency domain, thereby enabling the effective learning of changes in sensor data values. Moreover, autoencoder-based (AE-based) representation learning is utilized to extract features of the data, preventing overfitting and thus enhancing the robustness of the model. The experiment results demonstrate that the size and position of clamping force degradation can be accurately predicted. It is expected that this research will contribute to enhancing the precision and efficiency of internal structure monitoring in nuclear power plants.

Temporally resolved concentration profiling via computationally limited, distributed sensor nodes

AbstractAccurate mapping of chemical concentrations in reactor networks remains an obstacle to establish complete systems‐level insight and control. This issue extends beyond traditional reactor design to biological and other inaccessible systems of interest. Recent developments in novel materials with non‐volatile memory allow autonomous sensor nodes to record information with minimal external supervision. Integrating these materials in solution suspended particles demonstrates the unique potential for diffuse measurements of chemical data at the microscale. In this study, we establish a generalized workflow for the simulated deployment of time aware particle sensors (TAPS) in ideal reactor systems to measure analyte profiles, using Gillespie kinetic Monte Carlo algorithms (KMC). Our results show that computationally‐limited, chemically sensitive tracer particles capable of timestamping an analyte detection event can provide accurate analyte profiles throughout multistage reactors in an ensemble fashion.

Operation Optimization Framework for Advanced Reactors Using a Data-Driven Digital Twin

Abstract To meet future energy demand, while producing safe, reliable, and carbon-free energy, nuclear reactors will be needed. To make next-generation reactors more economically competitive, the Artificial Intelligence and Machine Learning-based operation optimization module of the dynamic operation and maintenance optimization (DyOMO) framework is proposed. The operation optimization module of DyOMO consists of a data-driven digital twin coupled to a genetic algorithm (GA) optimizer to quickly and efficiently search the solution space for optimal control schemes. The digital twin consists of a Bayesian Network (BN) known as MVCBayes to incorporate uncertainty in the optimization and feedforward neural networks (FFNN) as MVCNet with GA to conduct the optimization. Over time as reactor systems are operating, component degradation will cause the system's electrical output to decrease or be shutdown entirely to perform maintenance. To prevent this, the DyOMO operation optimization module aims to prolong system operation until the next scheduled maintenance period using multiple variable control (MVC) that simultaneously perturbs all actuators to better control the reactor. Comparing this approach with traditional single variable control (SVC), MVC can extend reactor operation past 5% degradation while SVC begins to struggle once the pump and turbine degradation surpasses 0.85% for load-following (LF) operation. Given this extra operation time, the system can continue to run while maximizing its safety margin until the next scheduled shutdown and potentially decrease the total number of maintenance actions throughout the license period to decrease operational and maintenance (O&amp;M) costs.

Introducing the Second-Order Features Adjoint Sensitivity Analysis Methodology for Neural Ordinary Differential Equations—II: Illustrative Application to Heat and Energy Transfer in the Nordheim–Fuchs Phenomenological Model for Reactor Safety

This work presents an illustrative application of the newly developed “Second-Order Features Adjoint Sensitivity Analysis Methodology for Neural Ordinary Differential Equations (2nd-FASAM-NODE)” methodology to determine most efficiently the exact expressions of the first- and second-order sensitivities of NODE decoder responses to the neural net’s underlying parameters (weights and initial conditions). The application of the 2nd-FASAM-NODE methodology will be illustrated using the Nordheim–Fuchs phenomenological model for reactor safety, which describes a short-time self-limiting power transient in a nuclear reactor system having a negative temperature coefficient in which a large amount of reactivity is suddenly inserted. The representative model responses that will be analyzed in this work include the model’s time-dependent total energy released, neutron flux, temperature and thermal conductivity. The 2nd-FASAM-NODE methodology yields the exact expressions of the first-order sensitivities of these decoder responses with respect to the underlying uncertain model parameters and initial conditions, requiring just a single large-scale computation per response. Furthermore, the 2nd-FASAM-NODE methodology yields the exact expressions of the second-order sensitivities of a model response requiring as few large-scale computations as there are features/functions of model parameters, thereby demonstrating its unsurpassed efficiency for performing sensitivity analysis of NODE nets.

Development of funnel-type fluidized bed reactor system using microcarriers for cultures of adherent cells

Development of funnel-type fluidized bed reactor system using microcarriers for cultures of adherent cells