Electrical Energy Input Research Articles

Self-supported ultrathin NiCo layered double hydroxides nanosheets electrode for efficient electrosynthesis of formate

Electrochemical CO2 reduction into energy-carrying compounds, such as formate, is of great importance for carbon neutrality, which however suffers from high electrical energy input and liquid products crossover. Herein, we fabricated self-supported ultrathin NiCo layered double hydroxides (LDHs) electrodes as anode for methanol electrooxidation to achieve a high formate production rate (5.89 mmol h−1 cm−2) coupled with CO2 electro-reduction at the cathode. A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO2 reduction can reach up to 188% driven by a low cell potential of only 2.06 V at 100 mA cm−2 in membrane-electrode assembly (MEA). Physical characterizations demonstrated that Ni3+ species, formed on the electrochemical oxidation of Ni-containing hydroxide, acted as catalytically active species for the oxidation of methanol to formate. Furthermore, DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni3+ in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation. This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.

Air leakage detection in building façades by combining lock-in thermography with blower excitation

Air leakage in building envelopes is responsible for a large portion of the building’s heating and cooling requirements. Therefore, fast and reliable detection of leaks is crucial for improving energy efficiency. This paper presents a new approach to determining air leakages in a building’s envelope from the outside, combining lock-in thermography and thermal excitation by a blower door system. The blower creates a periodic overpressure within the building, inducing periodic temperature variations of the surfaces near the leaks on the outside surface, the façade. With the temperature variations excited at a known frequency, Fourier transforms of the time-series of the thermal images at the excitation frequency result in amplitude and phase images highlighting the areas affected by leaks. Periodic excitation and detection by an IR camera is known as lock-in thermography and is widely used to characterise semiconductor devices and in non-destructive testing. Excitation is usually achieved by optical, electrical, or mechanical energy input. For this work, measurements of outside façades have been performed with three excitation cycles of a period of 40 s at a 75 Pa pressure difference, leading to a total measurement time of only 2 min. Measurements have been performed with air temperature differences of 5 to 7 K at highly variable conditions of irradiance, wind, and cloud cover. The measurements show higher detection quality and less impact from changing ambient conditions than the state-of-the-art differential infrared thermography measurements. With the method highlighting the variations in the amplitude image only at the excitation frequency, variations caused by environmental effects are filtered out. A temperature difference as low as a few Kelvin is therefore sufficient, and large façades can be examined from the outside. This amplitude image is already clearer than an image created with differential thermography. A further reduction of unwanted artefacts in the image is demonstrated using phase-weighing of the amplitude by scalar product.

Modulating the electronic structure of CoS2 by Sn doping boosting urea oxidation for efficient alkaline hydrogen production

Urea electrocatalytic oxidation afforded by renewable energies is highly promising to replace the sluggish oxygen evolution reaction in water splitting for hydrogen production while realizing the treatment of urea-rich waste water. Therefore, the development of efficient and cost-effective catalysts for water splitting assisted by urea is highly desirable. Herein, Sn-doped CoS2 electrocatalysts were reported with the engineered electronic structure and the formation of Co-Sn dual active sites for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), respectively. Consequently, the number of active sites and the intrinsic activity were enhanced simultaneously and the resultant electrodes exhibited outstanding electrocatalytic activity with a very low potential of 1.301 V at 10 mA·cm−2 for UOR and an overpotential of 132 mV at 10 mA·cm−2 for HER. Therefore, a two-electrode device was assembled by employing Sn(2)-CoS2/CC and Sn(5)-CoS2/CC and the constructed cell required only 1.45 V to approach a current density of 10 mA·cm−2 along with good durability for at least 95 h assisted by urea. More importantly, the assembled electrolyzer can be powered by commercial dry battery to generate numerous gas bubbles on the surface of the electrodes, demonstrating the high potential of the as-fabricated electrodes for applications in hydrogen production and pollutant treatment at a low-voltage electrical energy input.

An in-silico proof-of-concept of electrohydrodynamic air amplifier for low-energy airflow generation

Electrohydrodynamic (EHD) technology generates airflow without moving parts, making it a reliable solution for various low-energy applications. EHD-based airflow devices enhance airflow patterns, resulting in significant energy savings in air-moving systems. This airflow, also known as ionic wind, is created through Corona discharge, which accelerates electrically charged air molecules in a strong electric field. Currently, EHD's low electrical-to-mechanical energy conversion rate still limit its ability to generate large flow rates. The objective of this study is to enhance the flow rate of EHD-based devices, for applications where EHD can be used as an effective auxiliary technology with low pressure lift, to enhance airflow distribution and circulation. To this end, a novel bladeless air propulsion device is proposed that combines ionic wind with air amplification based on the Coanda phenomenon to amplify EHD-generated flow rates. We assess the performance of the bladeless air propulsion device to generate airflow by investigating fluid dynamics, electrostatics, and energy consumption. We demonstrate the proof-of-concept with an innovative fully-coupled simulation approach for corona discharge and EHD modeling. We explore different design parameters on the conceptual EHD air amplifier, such as the electric potential (10–30 kV) of the discharge electrode, the electrode spacing (5–25 mm), and the channel height (30–150 mm). The studies are performed on a 2D constrained channel flow and a 2D-axisymmetric open space design, respectively. In order to quantify the benefit of air amplification on EHD, the results are benchmarked to a regular EHD setup without amplifying vane as well as to a comparable commercial axial fan. We assess the performance in terms of flow rate per electric power input. Here, the EHD air amplifier in the constrained flow configuration increases the total flow rate by 59% compared to regular EHD and 48% compared to the axial fan for the same electrical energy input. Amplification factors of 16.5–19 are achieved for the constrained configuration and 5.5 to 6.4 for the open space configuration. The predicted energy consumption is 4–17.5 W for the open space configuration, resulting in flow rates up to 140 m3 h−1. These results show that EHD air amplification is a promising way to generate high flow rates with low pressure rise at a low electrical cost, by which it can provide a more sustainable alternative to conventional fans in specific applications..

Biomass gasification to syngas in thermal water vapor arc discharge plasma

This study investigated biomass (wood pellets) gasification to syngas using direct current (DC) thermal arc plasma at atmospheric pressure. Water vapor was used as a main gasifying agent and a plasma-forming gas. The biomass gasification system was quantified in terms of the producer gas composition, the tar content, the H2/CO ratio, the carbon conversion efficiency, the energy conversion efficiency and the specific energy requirements. It was found that the gasification performance efficiency was highest at the water vapor-to-biomass ratio of 0.97. The producer gas was mostly composed of H2 (43.86 vol.%) and CO (30.93 vol.%), giving the H2/CO ratio of 1.42 and the LHV of 10.23 MJ/Nm3. However, high content of tars of 13.81 g/Nm3 was obtained in the syngas. The yield of H2 and CO was 48.31% and 58.13%, respectively, with the highest producer gas yield of 2.42 Nm3/kg biomass. The carbon conversion efficiency and the energy conversion efficiency were 100% and 48.83%, respectively, and the production of 1 kg of syngas required 1.78 kWh of electric energy input. Finally, the obtained results were compared with different plasma methods, including plasma-assisted application coupled with conventional gasification.

Improvement of Piglet Rearing’s Energy Efficiency and Sustainability Using Air-to-Air Heat Exchangers—A Two-Year Case Study

Pig farming in mechanically ventilated barns requires much electricity for ventilation or exhaust air purification. Furthermore, thermal energy is needed to fulfill the animals’ temperature requirements, especially in piglet rearing. Electrical and thermal energy input leads to CO2 emissions and operating costs. Up to 90% of heat losses are due to the exhausted air. Heat exchangers can recover thermal energy from the warm exhaust air and transfer it to the cold fresh air. This study aimed to investigate energy consumption, efficiency, CO2 emissions, and energy costs when using heat exchangers in a German piglet rearing barn under practical conditions in combination with exhaust air purification. The following parameters were obtained for a two-year period: air temperatures, air flow rates, and electricity and liquefied natural gas consumption; the latter were used to calculate CO2 emissions and energy costs. In total, 576,042 kWhel,th and 616,893 kWhel,th (years 1 and 2) of energy were provided, including 290,414 kWhth and 317,913 kWhth of thermal energy recovered. Using heat exchangers reduced CO2 emissions by up to 37.5% and energy costs by up to 19.7% per year. The study shows that piglet rearing can increase its ecological and environmental sustainability by using heat recovery.

Humidity-stimulated film actuator with dual-responsive of bending deformation and discoloration

Flexible actuator can timely sense the changes of the external environment and respond accordingly. However, most intelligent response systems relied on the input of external electrical energy and can only trigger a single response, which cannot adapt to the changing environment. Here, the transparent actuating film TiO2/PVA-co-PE/SA was obtained by simple high-pressure spraying and immersion methods. Due to the excellent hygroscopicity of sodium alginate, the TiO2/PVA-co-PE/SA composite film can undergo rapid and reversible actuating deformation under external moisture stimulation. Meanwhile, the addition of titania-mica pearlescent pigment made the surface color of the composite film can be freely switched with the change of bending angle. Moreover, the actuating deformation and color variation showed excellent stability, and the maximum bending angle of the composite film can be maintained about 140°during ten consecutive cycles of moisture stimulation. The actuating film with synchronous change of shape and color has great significance in the research field of smart home and bionic system.

Dual-duty NiCo2S4 nanosheet-based solar rechargeable batteries toward multi-scene solar energy conversion and storage.

Solar energy has the potential to be the next-generation power source if the intermittent nature can be overcome via rational energy storage engineering. The competitiveness of solar rechargeable batteries can be further enhanced if the demand for multiple energy storage scenarios can be met within one device. Moreover, active electrochemical materials with different energy storage types are the critical component of this energy storage system. In this work, dual-duty electrochemical functional materials were introduced to guide multi-scene solar energy storage device design and fabrication. Furthermore, dual-duty NiCo2S4 nanosheets were prepared and applied to solar rechargeable batteries. A photo-assisted aqueous polysulfide/iodide flow battery was designed and fabricated with a charging voltage as low as 0.05 V, showing the good electrocatalytic performance of NiCo2S4 nanosheets for aqueous redox couples. Moreover, the low charging voltage leads to 93.5% of input electric energy saving under one sun illumination (AM 1.5, 100 mW cm-2). On the other hand is the photo-assisted sodium-ion battery with a NiCo2S4 anode, showing a remarkably low charging voltage of 0.67 V and a high discharge medium voltage of 1.05 V. The battery can save about 67.6% of input electric energy under 1 sun illumination.

An approach to harmonic optimization for 25KVA auxiliary converter used in indian railway

As the Indian railway network expands, the demand for reliable and efficient power systems, especially auxiliary converters supporting various on-board systems, grows. By reducing power losses and fuel consumption, it is more crucial to design an energy-efficient and economic auxiliary converter for the railway system. This is partially accomplished by using a 25KVA auxiliary (Aux.) converter, which can accept input electrical energy from a 110V DC battery at Self-Generation (SG) coaches. Biogeography Based Optimization (BBO) method of harmonic elimination for a 25KVA converter is described in this study. The paper explores the 120-degree mode of conduction and compares the existing technique with a proposed 7-switching selective odd harmonic removal method. Results from Matlab simulations demonstrate the effectiveness of the BBO technique in reducing Total Harmonic Distortion (THD). The output voltage waveforms with and without BBO are compared, showcasing a significant improvement in harmonic suppression. The paper concludes by emphasizing the practical implementation of the optimized switching angles using an ATmega2560R3 microcontroller. The online application of stored switching angles on the microcontroller is calculated offline.

Changes in Starch In Vitro Digestibility and Properties of Cassava Flour Due to Pulsed Electric Field Processing.

The research aimed to investigate the effect of pulsed electric field (PEF) treatment on cassava flour at mild intensities (1, 2, and 4 kV/cm) combined with elevated levels of specific energy input (250-500 kJ/kg). Influences on starch digestibility, morphological characteristics, birefringence, short-range order and thermal properties were evaluated. Application of PEF at energy input no greater than 250 kJ/kg had negligible influence on the different starch digestion fractions of cassava flour but raised the rapidly digestible starch fraction at a combined electric field strength >1 kV/cm and energy input >350 kJ/kg. Morphological evaluation revealed that at this PEF combination, cassava starch's external structure was consistently altered with swelling and disintegration, albeit some granules remained intact. Consequently, this led to disruption in the internal crystalline structure, supported by progressive loss of birefringence and significantly lower absorbance ratio at 1047/1022 cm-1. These physical and microstructural changes of the inherent starch promoted the shift in gelatinization temperatures to a higher temperature and reduced the gelatinization enthalpy. The study demonstrated that PEF can be utilized to change the starch fraction of cassava flour, which is driven by electric field strength and specific energy input, causing changes in the starch-related properties leading to increased digestibility.

Highly Dynamic Bistable Soft Actuator for Reconfigurable Multimodal Soft Robots

AbstractMatching the rich multimodality of natural organisms, i.e., the ability to transition between crawling and swimming, walking and jumping, etc., represents a grand challenge in the fields of soft and bio‐inspired robotics. Here, a multimodal soft robot locomotion using highly compact and dynamic bistable soft actuators is achieved. These actuators are composed of a prestretched membrane sandwiched between two 3D printed frames with embedded shape memory alloy (SMA) coils. The actuator can swiftly transform between two oppositely curved states and generate a force of 0.3 N through a snap‐through instability that is triggered after 0.2 s of electrical activation with an input power of 21.1 ± 0.32 W (i.e., electrical energy input of 4.22 ± 0.06 J. The consistency and robustness of the snap‐through actuator response is experimentally validated through cyclical testing (580 cycles). The compact and fast‐responding properties of the soft bistable actuator allow it to be used as an artificial muscle for shape‐reconfigurable soft robots capable of multiple modes of SMA‐powered locomotion. This is demonstrated by creating three soft robots, including a reconfigurable amphibious robot that can walk on land and swim in water, a jumping robot (multimodal crawler) that can crawl and jump, and a caterpillar‐inspired rolling robot that can crawl and roll.

Reduced Energy Cost of Ammonia Synthesis Via RF Plasma Pulsing

We have performed an extensive investigation of the parameters affecting the degree of nitrogen fixation and its energy cost in a low-pressure, radio frequency-driven plasma reactor. We find that the hydrogen-to-nitrogen ratio has a strong effect on both the yield and energy cost. A significant degree of nitrogen fixation (∼8%) can be achieved under hydrogen-rich mixtures, but unfortunately these conditions require a higher energy input compared to a one-to-one hydrogen-to-nitrogen ratio. The high degree of nitrogen fixation largely exceeds the degree of nitrogen dissociation in the plasma, suggesting that, while nitrogen dissociation in the plasma likely contributes to the ammonia yield, it cannot account for all of it alone. This confirms the importance of vibrational excitation in this class of processes, as it has been proposed by other research groups. In addition, our study indicates that hydrogen dissociation in the plasma is crucial for stabilizing reaction intermediates. Large-scale ab initio molecular dynamics simulations show that chemisorbed nitrogen is remarkably stable when hydrogen is present at the surface of a metal such as copper, which is otherwise a poor choice of catalyst for a heat-driven catalytic process. Finally, we have found that a pulsed-plasma regime provides a significant improvement in both yield and energy cost. The plasma not only activates surface catalytic processes but also dissociates the produced ammonia when operated in continuous mode. Under a pulsed mode, the plasma is extinguished before ammonia diffuses back into it from the catalyst surface, avoiding the waste of electrical input energy into redissociation of the desired reaction product.

Numerical Study on the performance of a heat pump-driven-DCMD for sustainable desalination

The study presents an energy-efficient desalination system that combines direct contact membrane distillation (DCMD) and a heat pump to improve thermal efficiency and integrate with photovoltaics. DCMD is a sort of thermal desalination process, and it requires a lot of thermal energy. A heat pump is a device that produces both hot and cold energy simultaneously with less electrical energy input compared to other heating devices, such as a boiler and an electrical heater. A hollow-fiber DCMD and a 10-kW water-to-water heat pump were considered for a numerical simulation in this study. Numerical models were established for each device and validated against the results obtained from the literature. The simulation was first carried out to identify the performance of the system based on the baseline. After that, a series of simulations were carried out in order to investigate the performance of the proposed system in terms of specific energy consumption (SEC), gained output ratio (GOR), and the coefficient of performance (COP) under various operating conditions. Results showed that the minimum SEC and the maximum GOR were achieved at the inlet feed water temperature of 66.5°C with a mass flow rate of 20 kg/min and the inlet permeate temperature of 19.8°C with a mass flow rate of 10 lpm. On the other hand, it was found that the maximum COP can be observed at the inlet feed water temperature of 23.6°C with a mass flow rate of 10 lpm and at the inlet permeate temperature of 8.9°C with a mass flow rate of 20 lpm.

Plasma drilling on Martian ice: Enabling efficient deep subsurface access to Mars' polar layered deposits

Mars' polar layered deposits (PLD) contain the best historical record of the Amazonian time period. Deep subsurface access at Mars' poles is challenging due to the restriction of Mars' atmospheric condition. Traditional terrestrial mechanical drilling methods using drilling fluids are not feasible in these conditions and the melting probe approach is very inefficient due to heat loss. For ice in Mars' polar condition, the increase in surface area due to cracks would greatly reduce its thermal conductivity. This will lead to a higher thermal efficiency and an easier access to polar layered deposits during melting or sublimation. The preliminary results with pulsed plasma ice drilling, using localized electric breakdown with electric energy input per pulse up to 80 ​J, were promising under both Mars and Earth conditions. To simulate Mars' polar condition, a vacuum vessel system was designed and implemented with a pulsed discharge circuit, ice plate, controlled liquid nitrogen cooling, and CO 2 gas feed-in. A simplified heat conduction model was established for estimating the heat conduction at various porosities for homogenous water ice and CO 2 gas mixture using COMSOL under two scenarios including constant thickness of mixture layer and constant thermal mass of the mixture layer under the heat source. The simulation results for both scenarios indicated more reduction of heat loss with an increasing porosity. Experimental studies of thermal conductivity measurement of granular ice under the Earth condition inside a freezer using a custom thermal needle probe with known porosity proved the concept that voids/cracks in ice can reduce the thermal conductivity. Based on simulation and experimental results, the classic melting probe model is extended with porous ice-CO 2 mixture to estimate the power consumption on Martian ice at varying descending speed. Plasma drilling with limited power is promising for accessing Mars' PLD and can also be expanded to planetary exploration in searching for life on other planets. • Plasma drilling method has no moving parts. • Pulsed plasma drilling improves the Rate of Penetration of the melting probe. • The cracks/voids in ice decreases its equivalent thermal conductivity. • Additional power requirement is acceptable within limited solar power access for Martian probe.

Trends and perspectives of microbial electrolysis cell technology for ultimate green hydrogen production

Currently, gray hydrogen and blue hydrogen are widely recognized as renewable energy, but in reality, they are made from fossil fuels. The most important task to achieve the hydrogen-based society is the development of economic green hydrogen production technology. Microbial electrolysis cell (MEC) is a next-generation energy-producing wastewater treatment technology that treats renewable organic wastewater and simultaneously produces the ultimate green hydrogen. For hydrogen production in MFC, it is necessary to input electrical energy into MEC. However, that energy is all covered by the energy produced by the MEC. Therefore, hydrogen production in MEC can be defined as the ultimate green hydrogen. This review contains an in-depth summary and analysis of the principles and feasibility of MEC technology, the composition and shape of MEC, electrode materials, and practical application cases in various types of wastewaters. Furthermore, compatibility and scalability with other environmental systems were reviewed at the pilot scale. Based on this, the technical limitations of MEC were diagnosed and future research directions for the practical application of MEC technology were suggested.

Local thermal effect of power-on setting on monopolar coagulation: a three-dimensional electrothermal coupled finite element study.

A three-dimensional (3-D) electrothermal coupled finite element (FE) model was used to simulate and analyze the effects of the electrosurgical power-on setting on the temperature distribution and thermal damage in biological tissue during coagulation. The discussed parameters include the power-on-off durations, contact distance between the electrosurgical blade and tissue surface, and inclination angle of the blade during cutting. The results indicate that under the condition of a constant input electrical energy, the maximal temperature decreased when the power-on time was shortened and the power-off (pause) duration was increased. The two contact distances between the blade and tissue (0 and 0.25mm) did not show a significant temperature difference; however, the tissue temperature increased with increasing blade inclination angle. We concluded that using a normal cut angle and set at a multiple shorter-time power-on with intermittent power-off operation procedure can reduce the risk of thermal damage during monopolar electrosurgery.

Reliability Parameter Evaluation of Wind Turbine Based on Minimization of Dynamc Loads Acting on Power Plant Structural Components

An evaluation method of minimization of dynamic loads of big wind wheels with horizontal axis of rotation by replacing a steel lattice tower with a concrete tube was considered as the basic approach to obtain the calculated data of wind power plant reliability evaluation parameters based on dynamic loads minimization acting on power plant structural components. A certain degree of dynamic load minimization acting on vanes based on duly system preparation for external disturbances due to prediction of wind speed and power of electric energy input resulted in load minimization per a vane by 20 %. The problem of parameter reliability evaluation of wind power plant based on minimization of dynamic loads acting on power plant vanes under the condition of duly system preparation for external disturbances was solved enabling increasing of run-to-failure mean time by 8 %. Evaluation analysis of dynamic load minimization acting on power plant structural elements based on optimization model that accounts drive loading conditions at various operation conditions of wind electrical power plant was performed, as the result of rotor system load (“wind wheel - the driving gear”, “gear - generator”) decrease constitutes 20 %. The problem of reliability evaluation parameters of wind electric power plant based on dynamic load minimization acting on power plant structural elements was solved by implementing optimization model of drive loading conditions at various operational conditions of wind electric power plant increasing the rotor system (“wind wheel - driving gear”; “gear - generator”) run-to-failure mean time by 18 %. It was found that the proposed methods of efficiency improvement of wind power plant control enable to increase the operation lifecycle of wind power plant by 26 %.

Boosting ethanol production rates from carbon dioxide in MES cells under optimal solventogenic conditions

Microbial Electrosynthesis (MES) has been widely applied for acetic acid (HA) production from CO2 and electricity. Ethanol (EtOH) has a higher market value than HA, and wide application in industry and as a biofuel. However, it has only been obtained sporadically and at low concentrations, probably due to sub-optimal operating conditions. This study aimed at enhancing EtOH productivity in MES cells by jointly optimising key operation parameters, including pH, H2 and CO2 partial pressure (pH2 and pCO2), and HA concentration, to promote solventogenesis. Two H-type cells were operated in fed-batch mode at −0.8 V vs. SHE with CO2 as the sole carbon source. A mixed culture, enriched with Clostridium ljungdahlii was used as the biocatalyst. The combination of low pH (<4.5) and pCO2 (<0.3 atm), along with high HA concentration (about 6 g L−1) and pH2 (>3 atm), were mandatory conditions for maintaining an efficient solventogenic culture, dominated by Clostridium sp., capable of high-rate EtOH production. The maximum EtOH production rate was 10.95 g m−2 d−1, and a concentration of 5.28 g L−1 was achieved. Up to 30 % of the electrons and 15.2 % of the carbon provided were directed towards EtOH production, and 28.1 kWh were required for the synthesis of 1 kg of EtOH from CO2. These results highlight that strict conditions are required for a continuous, reliable, EtOH production in MES cells. Future investigation should focus on improving cell configuration to achieve EtOH production at higher current densities while minimizing the electric energy input.

Experimental study of a full-scale hexagonal wet electrostatic precipitator for collection of black carbon and particulate matter generated by a marine diesel engine

ABSTRACT Wet electrostatic precipitators have demonstrated a robust capability for removal of particulate matter by minimizing back corona and particle re-entrainment of fine particles. The absence of studies investigating the removal of black carbon particles using a wet electrostatic precipitator requires additional development/investigations. Among the operational parameters of wet electrostatic precipitators, particle residence times (<1 s) and the amount of electrostatic energy transferred to the exhaust gas are important to determine the removal efficiencies of wet electrostatic precipitators. This article reports the removal efficiency of black carbon, total particulate matter, and various particle sizes using different operating conditions in a full-scale hexagonal wet electrostatic precipitator column with sequential cleaning. The exhaust gas cleaned during the experiments was produced by a 2 MW marine engine operated on heavy fuel oil. Three key parameters, voltage-current characteristics, transferred electrostatic energy to the exhaust gas, and particle residence times were varied to evaluate their effects on removal efficiencies. The wet electrostatic precipitator was able to remove from 42.7% to 97.2% of the particulate matter and 44.8% to 95.9% of black carbon particles by varying the electrical energy input to the gas stream (5–262 J/m3) and the particle residence time (0.3–1.8 s). A change in particle residence time (0.3 to 0.95 s) showed an overall removal increase of 31.7% and revealed removal efficiency gaps of up to 24.1% between particle sizes. By investigating the removal efficiencies of different particle sizes and black carbon content, it was found that the best fit was achieved for sizes between 0.02 and 0.77 μm, indicating a black carbon size range in this order. The study indicates that a similar removal efficiency between black carbon and particulate matter could be achieved and that the main focus for improvement of black carbon removal should be found in the particle range between 0.02 and 0.77 μm. Implications: The manuscript describes a small efficient system for the removal of particle matter and black carbon particles from the exhaust gas generated by a ship engine. This manuscript is especially interesting for the International Maritime Organization (IMO) and its sub-committee on Pollution Prevention and Response (PPR). The IMO is the law-maker/the United Nations specialized agency with responsibility for atmospheric pollution by ships in international waters. The IMO agreed in 2011 on an investigation plan to gather information and to find possible black carbon control measures for future regulations, which to some extent can be delivered through this article.

Simultaneous recovery of bio-sulfur and bio-methane from sulfate-rich wastewater by a bioelectrocatalysis coupled two-phase anaerobic reactor

The microbial electrolysis cell coupled the two-phase anaerobic digestion (MEC-TPAD) was developed for simultaneous recovery of bio-sulfur and bio-methane from sulfate-rich wastewater. In acidogenic phase, the produced sulfides were efficiently converted into bio-sulfur via anodic bio-oxidation, with a maximum recovery of 59 ± 5.5 %. The anode coupled acidogenesis produced more volatile fatty acids which were benefit for the subsequent methanogenesis. The cathode in methanogenic phase created a suitable pH condition and enhanced the methanogenesis. Correspondingly, the maximum bio-methane yield in MEC-TPAD was 2 times higher than that in TPAD. Microbial communities revealed that major functional consortia capable of sulfides oxidation (e.g. Alcaligenes) in anode biofilm, hydrogenotrophic methanogenesis (e.g. Methanobacterium) in cathode biofilm, and acetotrophic methanogenesis (e.g. Methanosaeta) in methanogenic sludge were enriched. Economic benefit could totally cover the cost of input electric energy. This work opens an appealing avenue for recovering nutrient and energy from wastewater.