Lowest Specific Energy Consumption Research Articles

Unlocking renewable fuel: Charcoal briquettes production from agro-industrial waste with cassava industrial binders

Increasing global fuel demand has created challenges in sourcing raw materials, making agro-waste biomass utilization for energy production a critical alternative. Therefore, the aim of this study was to investigate the production of charcoal briquettes using different base materials such as coconut shells (TC1), Leucaena leucocephala wood (TC2), and assorted wood charcoal residues (TC3), along with binders derived from cassava industry by-products—namely, tapioca starch (TB1), cassava peel (TB2), and cassava tubers (TB3) at binder content (BC) ratios of 5, 10, 15, and 20 by volume. Initially, assessing the physical properties, including proximate and ultimate analyses, was crucial for predicting effective charcoal production. The TC2 briquettes, using TB2 and TB3 binders at a BC20 concentration, were found to be optimal, displaying a high production capacity and low specific energy consumption. Using cassava peel and tubers as binders not only efficiently uses agricultural by-products, thereby reducing costs and avoiding competition with food resources (TC1) but also results in high-quality briquettes. In scenarios of raw material shortages, TC3 and TC2 can effectively replace TC1. Mechanically, TC3 and TC2 briquettes exhibited superior characteristics. Although BC20 enhances the mechanical properties and facilitates handling, it may compromise heat release. Thermally, a higher BC decreases the charcoal proportion, leading to increased ignition time, reduced calorific value, and heating effectiveness. In conclusion, the successful production of charcoal briquettes from agro-industrial waste using cassava industrial binders presents a viable pathway towards more sustainable energy practices, improves waste management, and adds value to agricultural waste.

Toward Continuous Electrochemical Synthesis of Ferrate

AbstractFerrate (Fe(VI)) is of great interest in energy storage solutions, organic synthesis, and wastewater treatment due to its decent oxidation potential and non‐toxic end‐product formation, making it a green oxidizer. The electrochemical generation of ferrate in NaOH at current densities of j ≥ 100 mA cm−2 is presented using low‐cost sacrificial iron anodes, mild steel, and spheroidal graphite cast iron (ductile iron). Under optimized reaction parameters with 40 wt.% (14 m) NaOH and a ZrO2‐based diaphragm, spheroidal graphite cast iron shows no signs of passivation in 5 h experiments even at j = 150 mA cm−2. The results are used in a novel electrolysis cell with a combined geometric anode surface area of 230 cm2, incorporated in a mini‐plant suitable for continuous synthesis. This setup produces a peak ferrate concentration of 10.1 g L−1 (84 mm) after 5 h in 1.6 L anolyte volume, resulting in a total ferrate mass of 16.2 g. Optimal electrolysis temperatures are between 35 and 50 °C. The highest current efficiency is 63.0%, and the lowest specific energy consumption is 9.2 kWh kg−1 ferrate. The presented work is an essential step toward the continuous electrochemical synthesis of ferrate using sacrificial anodes under basic conditions.

Uranium removal from contaminated groundwater using goethite-loaded composite microporous membrane

In this study, we have coupled adsorption and membrane separation for the removal of uranium from contaminated groundwater in environmentally relevant conditions at low energy requirements. This study mainly focuses on elucidating uranium, U(VI), adsorption mechanisms using surface complexation modeling approach in a novel goethite-loaded composite microfiltration membrane (GLM). This experiment involved immobilizing goethite nanorods in a microporous (0.22 μm pore size) poly (vinylidene fluoride) (PVDF) membrane. The effect of varying goethite loading and hydraulic residence time on U(VI) removal was investigated at field-relevant pH (i.e. pH 8.5). U(VI) adsorption (i.e. 4.95 μg·mg−1) was optimum at a goethite loading 1.20 mg·cm−2. The effect of varying hydraulic residence time had no impact on U(VI) removal which was also confirmed via performing batch adsorption kinetic experiments. GLM membrane loaded at 1.2 mg·cm−2 could treat 275 L of U(VI) contaminated water having 200 μg of U L−1 below WHO drinking water limit (i.e. 30 μg of U L−1) with 1 m2 of membrane surface area with a adsorption capacity of 6.12 μg·mg−1. Varying the pH of aqueous solution, containing U(VI) from pH 4.0 to pH 10.0, showed a significant impact on uranium uptake ranging from 0.7 μg·mg−1 to 2.63 μg·mg−1 by the composite membrane. The adsorption mechanism of uranium onto goethite was explained via the formation of bidentate surface complexes using the Surface Complexation Model (SCM). The results of batch pH edge experiments and SCM have been compared with pH experiments performed using GLM. The results of SCM predicted the batch pH edge experiment within a RMSE of 0.055. The trend of U(VI) removal in membrane experiments was observed to be similar to that of batch pH edge experiments and was well predicted SCM model. Our results showed that the novel goethite-loaded membrane has the potential for the effective removal of uranium with a lower specific energy consumption.

Analysis of in-bin low-temperature and high-temperature grain drying in Alberta: Specific energy, carbon costs and policy implications

Optimizing grain drying process is pivotal for both economic viability and environmental sustainability. In cold countries, supplemental heating is paramount but instigates the issue of carbon release at the same time. To curve the emission, a carbon levy has been imposed that varies with fuel types. However, there is limited knowledge of the impact of field-adaptable technologies utilizing commercialized fuels on the optimal execution of grain drying. To explore this, a comprehensive three-year on-farm grain drying study was conducted in the province of Alberta, Canada. This comparative analysis centered on three critical aspects, i.e., specific energy consumption, greenhouse gas emissions (GHGs), and operating costs. Furthermore, the research extended its projections into the year 2030, accounting for the impact of gradual carbon levies on natural gas, propane, and diesel fuel systems. Resultsshowed that indirect heaters in in-bin systems were 38 % more energy-efficient than direct heaters due to better airflow and higher initial grain temperatures, while indirect heaters with diesel burners exhibited 27.8 % lower burner turndown ratios and 35.4 % higher energy consumption than natural gas counterparts. In high-temperature drying, natural gas consumption decreased as supply air temperatures rose, with double-flow dryer showing the lowest energy consumption (6.3±1.9 GJ/t) in comparison to mixed-flow and cross-flow dryer due to waste heat recovery. Heaters and Dryers operated at varying load capacities, indicated 126–135 % increase in natural gas cost with carbon levy by 2030. Achieving lower specific energy consumption in grain drying requires precise burner and process control, along with maintenance, offering valuable guidance for producers.

Chemical structure dependent electrochemical degradation of antibiotics using Boron-doped Diamond Electrodes

The electrochemical degradation of Amoxicillin (AMOX), Ciprofloxacin (CIP), and Streptomycin (STR) utilizing Boron-Doped Diamond Electrodes (BDD) was explored under varying levels of applied electrical current density and initial buffer acidity. These pharmaceuticals were carefully selected to showcase the efficiency of electrochemical oxidation across different major chemical structure antibiotic families. The results demonstrated a positive correlation between higher applied current density and the elimination of antibiotics, as well as enhanced chemical oxygen demand (COD) removal rate. However, a negative impact was observed on the specific energy consumption (SEC). Notably, the highest antibiotics and COD removal efficiencies, along with the lowest SEC, were achieved at an applied current density of 45 mA/cm2. Furthermore, the investigation highlighted the significant influence of the chemical structure of the selected antibiotics on their degradation process. At a current density of 15 mA/cm2 and after 24 minutes of treatment, the degradation order was found to be AMOX > CIP > STR, with respective antibiotic removal efficiencies of 98.5 %, 87.8 %, and 81.1 %. Similarly, after 90 minutes of treatment, the COD degradation efficiency followed the order AMOX (50.4 %) > CIP (47.3 %) > STR (44.6 %), accompanied by decreasing levels of specific energy consumption, measuring 59, 61, and 67 kWh/kg COD, respectively, with an average current efficiency of 23–26 %. The pH had a significant effect on the streptomycin degradation rate, while it had a negligible impact on the degradation rate of ciprofloxacin. These findings shed light on the critical role of the pharmaceuticals' chemical structures and environmental conditions in governing the efficiency of their electrochemical degradation.

Ultrasound-assisted vacuum drying of limequat peels and characterization of thermal, morphological and functional properties

This work aimed to determine drying behavior and energy consumption of limequat peels dried using ultrasound-assisted vacuum drying (UAVD), vacuum-assisted drying (VAD), oven drying (OD) and vacuum drying (VD), and investigate thermogravimetric decomposition, morphological, elemental and spectral analyses of dried peels with energy efficiency analysis including specific moisture extraction rate (SMER), moisture extraction rate (MER) and specific energy consumption (SEC). The UAVD considerably shortened drying time by 49 %, 34 % and 15 % as compared to the OD, VAD and VD. The highest drying rate was achieved at the UAVD. The effective moisture diffusivity(Deff) values in descending order were UAVD>VD>VAD>OD. Proximate analysis showed that limequat peels dried using the UAVD had the highest fixed carbon (25.35 %) and ash (3.03 %) contents, but the lowest volatile matter (61.68 %). Dried limequat peels exhibited similar thermal decomposition behavior. The UAVD caused porous and rough surface formation, and microchanneling effect. Carbon (>62.56 %) and oxygen (>15.98 %) were the major elements in dried limequat peels. The lowest O/C (0.25) and H/C (0.85) ratios were obtained for the limequat peels dried using the UAVD. Fourier-transform infrared spectroscopy (FTIR) spectra showed primarily O–H, C–H, CO, CC and C–O–C stretching vibrations. The highest SMER (0.0053 kg/kWh) and MER (0.0012 kg/h) values, and the lowest SEC (188.27 kWh/kg) value were determined for the UAVD. In conclusion, the UAVD was found to be the most appropriate drying method for the drying of limequat peels.

Enhanced capacitive deionization via modulating local electron of electro-adsorption sites in a Trace-Fe-modified carbon framework

In order to alleviate the crisis of freshwater resources, it is essential to explore a clean, efficient, and low-consumption water treatment technology. As a kind of electro-adsorption water purification technology, capacitive deionization (CDI) has drawn continuously growing attention because of its advantages. The ion adsorption capability of CDI is closely related to the electrodes. Unfortunately, the ion adsorption capacity of common carbon materials is limited and far from reaching the rapidly increasing requirements of fresh water treatment. In this study, Fe-N-HPC electrode materials with trace Fe uniformly dispersed in N-doped hollow carbon polyhedral frameworks were tactfully prepared by a simple in-situ growth and pyrolysis method. The structure and morphology of the heterostructure material were verified by various analysis. Electrochemical tests showed the Fe-N-HPC electrode had an enhanced performance with a higher specific capacitance and fast ions diffusion coefficient. The Fe-N-HPC showed excellent CDI performance, with an enhanced desalinization capacity (34.38 mg/g, 500 mg/L NaCl solution, 1.2 V), and regenerative stability after 100 adsorption–desorption cycles. In addition, it also exhibited higher charge efficiency, energy efficiency and lower specific energy consumption. The removal mechanism of Na+ on the electrode and the participation of trace Fe can modulate the local electron of the electro-adsorption sites were reasonably verified by ex-situ XRD, Raman, and XPS characterizations, which finally facilitated the electro-adsorption property. This work presents a promising scheme for the advance of high efficiency capacitive desalination system.

Enhancing diesel engine performance and emission reduction through hydrogen enrichment in algal biodiesel blends.

The introduction of hydrogen into the engine could enhance its combustion efficiency and emission characteristics. The current study examines the attributes of compression ignition (CI) engines by introducing hydrogen into a biodiesel blend derived from algae. The improved thermal properties of hydrogen, when combined with algae biodiesel, significantly affect the performance, combustion, and emissions of dual-fuel engines. A study was conducted to evaluate the impact of hydrogen enrichment levels of 5%, 10%, 15%, and 20% of the nozzle volume on a biodiesel blend fuel. In comparison to diesel, algal biodiesel reduces emissions of unburned hydrocarbons (HC), carbon monoxide (CO), and oxygen (O2) by 5.19%, 3.61%, and 2.83%, respectively, while increasing nitrogen oxide (NO) emissions by 4.73%. In contrast to biodiesel, diesel demonstrated superior brake thermal efficiency (BTE) and lower specific energy consumption (SEC). Injecting hydrogen into A20 blend fuel at volumes of 5%, 10%, 15%, and 20% results in a respective increase in brake thermal efficiency of 2.65%, 2.97%, 3.50%, and 4.15%. The addition of hydrogen gas to biodiesel blends further enhances their combustion qualities, leading to elevated peak cylinder pressure, temperature, and heat release rate. The results indicate that A20H5, A20H10, A20H15, and A20H20 fuel reduced CO emissions by 3.75%, 8.75%, 12.5%, and 16.25%, respectively, compared to the A20 blend. In the same vein, HC emissions decreased by 5.76%, 10.29%, 15.52%, and 18.98%, respectively, as compared to A20 fuel. However, NO emissions rose by 5.36%, 10.20%, 15.28%, and 23.23%, respectively, for A20H5, A20H10, A20H15, and A20H20 test fuels. Ultimately, the utilization of algal biodiesel and hydrogen enrichment in diesel engines was proven to substantially reduce pollutants while increasing efficiency. This study contributes valuable insights into the intersection of renewable fuels, hydrogen enrichment, and engine technology, with the potential to drive significant advancements in sustainable transportation and environmental conservation.

Recovery of highly pure copper from waste cupronickel by electrolysis separation with low energy consumption: The role of deep eutectic solvent

The recovery of waste cupronickel not only can solve related environmental concerns but also facilitates the separation of valuable metals and reduces extra exploitation of natural ore resources. Here, high-efficiency and low-energy-consumption separation of copper (Cu) from waste 90/10 cupronickel (Ni ∼ 10 %) by electrolysis was clarified in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES). Electrochemistry showed that Cu can be dissolved feasibly as monovalent Cu(I), forming species such as [CuCl2]− and [CuCl3]2−, while Ni was restrained and entered into anode slime at controlled potential. Compared with Ni(II), Cu(I) can be easily reduced to Cu0, and elevating temperature can accelerate ions transportation and reduction rates. Potentiostatic electrolysis at bath voltage of 0.4 V found that highly pure Cu (99.9918 wt%) was obtained and the current efficiency reached up to 99.71 % with low specific energy consumption (169.18 kW·h·t−1). A separation mechanism model of Cu from waste 90/10 cupronickel was proposed and the role of the DES was revealed, which possessed strong coordination ability and fast transport capacity for Cu(I), as well as significant potential difference between Cu and Ni. This strategy represents a promising and economical technique for recycling waste Cu-based alloy and extracting highly pure metals.

Electrochemical and bioelectrochemical treatment of steam-assisted gravity drainage water

This study compares electrochemical and bioelectrochemical approaches for treating Steam-Assisted Gravity Drainage (SAGD) water. Electrochemical treatment tests were carried out at applied voltages (Vap) of 1.4, 2.0, and 2.5 V. Bioelectrochemical treatment in a Microbial Electrolysis Cell (MEC) was conducted at the same applied voltages with microaeration of both electrode compartments. The two treatment approaches were thereafter combined in a continuous flow setup that consisted of an electrochemical cell (EC, Vap = 2.5 V) followed by MEC (Vap = 1.4 V). Chemical oxygen demand (COD), naphthenic acid, dissolved metals, and metalloid concentrations of SAGD water were substantially reduced after all treatments, thereby rendering the treated water less toxic according to ecotoxicological tests. However, the MEC treatment was more energy efficient resulting in the lowest specific energy consumption (SEC) value of 5.2 kWh/kgCOD. By replacing a Ti/IrO2-oxide current collector in the MEC with a custom-made Ti/NiCo-oxide mesh, the COD removal efficiency improved by 30%. The results suggest that a MEC equipped with Ti/NiCo-oxide current collector can provide cost-efficient treatment of SAGD water.

Comparison and optimization of CO2 purification units for CCS applications

Several promising CO2 capture technologies, like oxy-combustion, adsorption and membranes, feature a purity of the captured CO2 stream which is insufficient for the storage site or the transport system. In these cases, a CO2 Purification Unit (CPU) is required to lower the concentrations of O2, N2 and Ar at the limits allowed by the storage site/transport system. In this work, the available CO2 Purification processes have been reviewed and the six main schemes have been simulated in Aspen Plus and optimized. Their performance have been ranked based on six selected key performance indicators: total annual cost, Specific cost per ton of captured CO2, specific energy consumption, recovery, purity, and O2 concentration in the purified CO2. The techno-economic optimization is repeated for different carbon tax values and for three different feed streams compositions. The results of the optimization show that flash-based CPUs cannot meet the requirements for CO2 storage due to a high concentration of O2 (>1000 ppm) but they feature a low specific cost (5.8–25.9 €/tonCO2 depending on the feedgas and plant size), low specific energy consumption (124.9–436.1 kJ/tonCO2) and acceptable recovery (94.60–99.46 %). The distillation-based CPU can meet the requirements for CO2 storage, but these CPUs have the highest cost (52–112 % higher than flash-based CPU) and the lowest recovery. The optimal CPUs are the ones which combine both distillation column and flash separation. These CPUs meet the oxygen requirements for CO2 storage (<10 ppm) while providing the highest purity (99.997–99.999 %), high recovery (90.61–99.32 %) at a limited cost (6.1–36.0 euro/tonCO2).

Determination of the characteristics of drill string vibrations during the drilling process

The object of research is vibration processes of a certain origin in the drill string with typical design deviations depending on the mode parameters of drilling. A drill string is an oscillating system with an infinite number of degrees of freedom of a multifactor system. An exhaustive study of oscillatory processes in the drill string is impossible neither analytically nor experimentally, due to the specifics of the hole deepening in various rocks, the design of the well, its shape, etc. Therefore, in practice, they try to solve the problems of the dynamics of the drill string for an idealized system and, while preserving the main oscillatory properties, solve some problems of the rod system. The work carried out was aimed at experimental studies of vibrations of the drill string during the drilling process. It is shown that the effectiveness of the use of hydrodynamic cavitation requires the development of methods and devices for intensifying the well drilling process. It is proven that the design of the cavitation generator organically fits into the existing well drilling equipment and allows for the intensification of technological processes with lower specific energy consumption. It is found that all oscillatory processes that occur in the drill string are random in nature and must be considered using the mathematical apparatus of the theory of random oscillations. The study of vibrations during well drilling shows that vibrations can be considered as random stationary processes, since transient modes have a sufficiently short duration for homogeneous rocks with fixed drilling modes. The analysis of the vibrations of the drill string elements based on random oscillations in a number of cases allows to increase the reliability of determining the vibration reliability of the drill string elements. It has been proven that the response of drill string elements to broadband random vibration can be defined as the combined effect of several narrowband random vibrations.

EXPERIMENTAL INVESTIGATION OF NEWLY DEVELOPED ELECTROLYTIC MAGNETIC ABRASIVE FINISHING SETUP WITH MULTIPLE POLE SYSTEM FOR FINISHING OF ALUMIUM WORKPIECE

The procedure of combining abrasion machining with chemical machining is the most demanding and crucial method of machining, because it guarantees higher levels of quality from the part. Combined procedure for machining are typically employed as the last step in the machining process, and their significance grows progressively crucial while a nano finished surface of the work piece material is necessary. The subject of nano surface finishing of materials via chemical machining and abrasion has advanced recently. Electrolytic magnetic abrasive finishing (EMAF) is a procedure that combines chemical and magnetic energy to achieve a desire finish. During the EMAF process, The work piece fits in the middle among two magnetic poles. A mixture of abrasives and ferromagnetic particles fills the gap between each pole and the workpiece. The electrode is positioned at a certain distance from the workpiece, and both are linked to a direct current (DC) power source. An electrolytic solution is circulated between the gap using a pump. The method offer a wide range of industrial applications because to its low specific energy consumption and enhanced surface finishing. This study presents the creation of a novel EMAF with multiple pole system. It further looks into the impact of different process attributes include machining time, rotational speed, size of the abrasive particles, electrolytic concentration and weight of the abrasive particles on the improved performance of material removal rate (MRR) and surface finishing (PISF).

Online monitoring of the size distribution of lime nodules in a full-scale operated lime kiln using an in-situ laser triangulation camera

To maximize efficiency of the recausticizing process in a pulp mill, producing a reburned lime with high and consistent reactivity is process critical. Prior investigations have demonstrated a correlation between the reactivity of lime and its nodule size, as well as the dusting behavior of the kiln. Therefore, monitoring the nodule size produced in the lime kiln could be a promising indirect method to measure the performance of the lime kiln. The objective of this investigation was to evaluate the utility of a laser triangulation camera for online monitoring of nodule size distribution for the lime kiln. A series of full-scale trials were performed in a lime kiln of a kraft pulp mill in which a camera was installed at the exit conveyor to analyze the lime discharging from the kiln. The nodule size distribution was analyzed for correlation with the lime temperature, flue gas temperature, and rotational speed of the kiln. The monitoring demonstrated temporal stability, and the results showed that the lime temperature had the most significant effect on the nodule size. The rotational speed of the lime kiln and the flue gas temperature showed limited effect on nodule size, but they had significant impact on the specific energy demand. The overall conclusion of the study is that the camera methodology effectively correlates lime temperature with nodule size distribution, and it advocates for the methods of implementation in automating lime temperature control, facilitating the production of consistently reactive lime at a lower specific energy consumption.

Experimental study on ammonia-diesel co-combustion in a dual-fuel compression ignition engine

Ammonia, as a carbon-free renewable fuel and a potential hydrogen carrier, is gaining increasing interest in addressing greenhouse gas emissions in industrial applications and transportation. This paper presents experimental studies on the co-combustion of ammonia with diesel fuel in a single-cylinder industrial compression ignition engine operating in dual-fuel mode. The energy share of ammonia ranged from 0 to 60%. Increasing the proportion of ammonia compared to diesel fuel in the compression ignition engine leads to a change in the combustion process character, increasing the kinetic combustion phase at the expense of diffusive combustion. However, it does not result in an increase in the peak pressure rise (PPR) beyond the permissible value of 1 MPa/deg for piston engines. It increases ignition delay and shortens the combustion duration, while also increasing thermal efficiency and decreasing specific energy consumption. An increase in the NH3 share results in a decrease in combustion efficiency, a reduction in unit emissions of NO, CO2, and soot, and an increase in CO emissions. Beyond 42% ammonia share, it reduces unit THC emissions. At a 42% ammonia share, the dual-fuel engine achieves the highest indicated thermal efficiency (ITE), lowest specific energy consumption (SEC), shortest combustion duration, and lowest unit soot emissions.

BDD-persulfate-based anodic oxidation process for progestin degradation: Optimization of conditions, eco-compatibility tests, and cost evaluation

Considering the increasing presence of the hormones levonorgestrel (LNG) and gestodene (GES) in wastewater, the limited effectiveness of conventional treatment methods, and the demand for advanced complementary processes, our study aimed to optimize an anodic oxidation treatment with a focus on low specific energy consumption (SEC) and costs. An electrochemical system coupled to a boron-doped diamond anode (BDD) was continuously used to treat synthetic and real pharmaceutical wastewater from contraceptive production. The central design composite and response surface methodology were the tools employed for optimization. The lowest SEC was obtained as a response to the main process variables: current density, initial pH, and the concentration of the support electrolyte ([Na2S2O8]). The optimal condition ([Na2S2O8]0 = 0.07 mol L−1; [LNG]0,RPW = 1.02±0.05 mg L−1 and [GES]0,RPW = 1.05±0.05 mg L−1; j = 37.5 mA cm−2; pH = 6.75) was established considering an SEC ≤ 3.6 ± 0.8 kWh g−1 and progestins removal ≥70%, which was the experimental condition used to evaluate acute toxicity to Daphnia similis and the effect on estrogenic activity removal using the YES assay. Notably, our study evaluated, for the first time, a comparative investigation that highlights the substantial effect of support electrolytes over the eco-compatibility assessment of the anodic oxidation process investigated. The adaptability of the operation indicates the prospective suitability for the implementation of the process in wastewater treatment facilities in the pharmaceutical industry.

Navigating the balance between nanofiltration and oxidation to remove organic micropollutants from wastewater treatment plant effluent

The removal of organic micropollutants (OMPs) from wastewater treatment plant effluent is becoming more important due to the adverse effects of these compounds on the environment. To overcome the limitations of currently available technologies, this study proposes a combination of hollow fiber membrane filtration with advanced oxidation to remove OMPs. The possible synergy between these processes was investigated. The nanofiltration membrane ensures the removal of organic matter and thus an improvement of transmittance, after which oxidation with UV/H2O2 of the permeate can remove OMPs more effectively and at a significantly lower energy consumption than without a membrane. Six membranes were evaluated with a pure water permeability between 6.7 and 106 Lm−2 h−1 bar−1 and a MgSO4 retention ranging from 0.93 to 0. The molecular weight cut-off (MWCO) varied from 250 Da to more than 10 kDa. The measured MWCO can depend strongly on the applied flux. The UV-transmittance of NF permeate of treated wastewater was investigated experimentally to be between 97% and 50%. These values were used for an estimation of the specific energy consumption (SEC) for the membrane and the oxidation step, resulting in a combined SEC of 0.17–0.18 kWhm−3 for 70 or 80% removal of OMPs, respectively. Remarkably, this lowest SEC was not found for the combination with the most dense membrane, but for a slightly more open membrane. The reported SEC is comparable to the total energy consumption required for ozonation and adsorption, while producing clean water with a double barrier, high transmittance and 70–80% removal of OMPs.

Improving ammonia nitrogen removal and recovery by BMED stack optimization: The effect of ion exchange membrane thickness

Bipolar membrane electrodialysis (BMED) has emerged as an efficient and promising technology for the removal and recovery of ammonia nitrogen. Despite its potential, the optimization of BMED systems for enhanced performance and energy efficiency remains a critical challenge, particularly in the context of varying ion exchange membrane (IEM) thicknesses. Membranes with a thickness of < 80 µm have low resistance and are mainly used for processes requiring low energy consumption. Membranes with a thickness of 80–250 µm have moderate resistance and high ion selectivity and are widely used for electrodialysis applications. Membranes with a thickness of > 250 µm have higher ion selectivity than commercial membranes with a thickness of 80–250 µm and are suitable for processes that demand high purity. This study investigates the effect of IEM thickness ranging from 16–400 µm on BMED performance for ammonia nitrogen removal and recovery, and energy consumption. The BMED configuration comprising five cell triplets consisting of a cation exchange membrane, bipolar membrane, and anion exchange membrane was employed. The thickness of IEMs was divided into three categories: 16–17 µm (PCEM/ PAEM), 100–150 µm (CD100/AD100, InnoSep-C/InnoSep-A), and 380–400 µm (MC-3470/MA-3475). In membranes with a thickness of 100–150 µm, the ammonia nitrogen removal was exceptionally high at 99.2 %, with a recovery of 98.7 % (CD100/AD100: 100 µm) at a current density of 80 mA/cm2, and the system exhibited low specific energy consumption (SEC) of 8.87 kWh/kg-N (InnoSep-C/InnoSep-A: 150 µm) at a current density of 20 mA/cm2. However, when using the thinnest IEMs (PCEM: 16 µm, PAEM: 17 µm), an increase in total ammonia nitrogen loss (10.21–22.01 %) led to a reduction in ammonia nitrogen recovery. Conversely, when using the thickest IEMs (MC-3470: 380 µm, MA-3475: 400 µm), the SEC was extremely high (30.98–126.67 kWh/kg-N), making them unsuitable for the BMED process for ammonia nitrogen removal and recovery. Based on these experimental results, it is suggested to use an optimal thickness of IEM within the range of 80–250 µm in the BMED systems to achieve a balanced performance, maximizing ammonia nitrogen removal and recovery while minimizing the SEC. Consequently, the present study provides a comprehensive understanding of the effects of the IEM thicknesses on the BMED systems and could offer a practical perspective for optimizing the BMED stack with respect to improving the removal and recovery rate of ammonia nitrogen and reducing the energy consumption.

The effect of pretreatments on the drying of persimmon with infrared energy

AbstractThe effects of various pretreatments, including edible coatings, on drying kinetics and some physical quality parameters of persimmon varieties (Fuyu and Rojo Brillante) and differences between varieties were investigated. The experiments were conducted at an infrared radiation intensity of 1210 W m−2 and air velocity (v) of 1.5 m s−1. Drying time differed depending on pretreatments and varieties. Pretreatments generally shortened the Fuyu variety's drying time and increased the Rojo Brillante variety's drying time. Lower specific energy consumption and higher diffusion coefficient values were recorded for the Rojo Brillante variety compared to the Fuyu. In terms of quality parameters, the Fuyu variety generally obtained lower values for shrinkage. Rehydration rate was higher for the Rojo Brillante variety. Total color change was lower in the Rojo Brillante variety. Based on the pretreatments applied, xanthan gum gave better results in terms of operational parameters. In terms of quality parameters, ascorbic acid had better results for rehydration rate and shrinkage. For total color change, better results were obtained in arabic gum pretreatment. As a result, when an evaluation is made regarding variety differences and pretreatments applied, the Rojo Brillante variety can be recommended for drying.Practical applicationsPersimmon is a popular fruit in appearance, flavor, and rich nutritional content. The high moisture and sugar content in the fruit increases spoilage in a short time, making it difficult to consume in all seasons. For this reason, different preservation methods are being investigated to extend the shelf life. Sun drying and other drying methods developed as an alternative to these methods have many disadvantages. Different pretreatments prevent the negativities that occur in other drying methods. Especially, edible coatings can increase product quality by preserving color and appearance as well as controlling mass transfer, flavor, and aroma losses. This study investigated the effects of various pretreatments, including edible coatings, on drying kinetics and some physical quality parameters of persimmon varieties, as well the differences between varieties. Based on variety differences and pretreatments applied, the Rojo Brillante variety can be recommended for drying in terms of both processing and drying characteristics.

Study on a novel hydrogen liquification process applying mixed-refrigerant for pre-cooling and cryogenics

Reducing the energy consumption of hydrogen liquefaction process is an urgent issue to improve the economy of liquid hydrogen transportation. A novel large-scale hydrogen liquefaction system, with a capacity of 100 TPD, is proposed in this paper. The pre-cooling system is composed of a mixed-refrigerant (MR) refrigeration cycle and a CO2–NH3 cascade refrigeration cycle. Due to the auxiliary pre-cooling effect of the CO2–NH3 cascade cycle, temperature of the pre-cooled hydrogen can be as low as −200.9 °C. A modified MR Joule Brayton cycle with an additional compressor is used as the cryogenic system to cool the hydrogen from −200.9 °C to −252.2 °C. Besides, a four-stage ortho-to-para conversion (OPC) process is utilized. Performance of the novel system is investigated and optimized using the Aspen HYSYS software. According to the results, the lowest specific energy consumption (SEC) of the proposed process is 6.15 kWh/kgLH2 and the exergy efficiency is as high as 67.4%. Based on the energy analysis, the best system coefficient of performance is 0.1751 with a 96.3% of p-H2 in the liquid hydrogen. In addition, compared to the initial conceptual system, the proposed system exhibits significant performance enhancements, a 20% reduction in SEC and a 27.9% increase in exergy efficiency. A sensitivity analysis is conducted to assess the impact of refrigerant composition and hydrogen pressure on the system, resulting in the determination of the optimal proportions of refrigerant components and the optimal inlet pressure. Results of the study can provide theoretical reference for the further development of large-scale hydrogen liquefaction technology.