Minimum Energy Input Research Articles

Building Electrochemical Roadmaps for Decarbonization in the Specialty Chemical Sector

Greenhouse gas emissions from the chemical manufacturing industry are enormous, by some estimates they amount to 5% percent of the global total.1,2 Moreover, chemical manufacturing is widely considered as a “difficult-to-decarbonize” sector due to the deeply entrenched reliance on crude-based hydrocarbons as fuels and feedstocks.3 The ultimate goal of eliminating anthropogenic greenhouse gas emissions, clearly demands a wholesale reconsideration of energy and material flows in chemical manufacturing.One area of research that has gained momentum in the past decade is the use of electrochemistry to perform organic redox reactions. These types of electrosynthetic transformations provide a straightforward means to electrify chemical manufacturing, thereby decreasing the global warming impact as the carbon intensity of grid electricity diminishes with continued adoption of low-carbon power sources. Further improvements are achievable through decarbonization of material inputs, e.g., by replacing problematic redox reagents like methane-derived hydrogen or fuming nitric acid with reactive hydrogen and oxygen intermediates generated at electrodes via water electrolysis.Despite these promising advances, interest in organic electrosynthesis to date has mainly focused on the production of commodity chemicals (e.g., CO2 reuse, ammonia electrosynthesis) at the expense of specialty chemical synthesis. This focus is well justified based on the possible impact of major breakthroughs on global emissions, but it constitutes missed opportunities to drive broad adoption of electrosynthesis across the chemical industry. To address this knowledge gap, our lab has undertaken a collaborative research effort with a global specialty chemical manufacturer to explore opportunities to decarbonize through electrification strategies involving electrosynthetic reaction schemes.This presentation will detail our recent work on a holistic “scoping study” to estimate the potential for reducing the global warming emissions profiles for a representative set of specialty chemicals through the adoption of electrosynthetic methods. First, we mapped the supply chain for 12 specific chemicals (chosen for their relevance to the specialty industry and significant global warming potential from current production methods) in terms of all reactive processes required to generate these compounds from petrochemical feedstocks. Next, we searched for literature reports detailing electrosynthetic pathways to generate each intermediate species along the manufacturing supply chain. The relevant electrochemical reactions were broadly classifiable as (a) generating alternatives to petrochemical feedstocks; (b) direct replacement of an existing chemical redox reaction with an electrochemical reaction; or (c) intensified approaches that use electrochemistry to reduce the total number of reactive process steps required. Finally, we benchmarked the potential for reduced greenhouse gas emissions for electrosynthetic schemes compared to the incumbent technologies based on a set of simplifying assumptions that involve calculating baseline emissions intensities as a function of the thermodynamic minimum energy input and the carbon intensity of the electric power supply, and further applying generic “efficiency factors” to account for all emissions in excess of this thermodynamic minimum. The results of this analysis suggest remarkable opportunities to develop electrosynthetic schemes for a handful of reactions for which global warming emissions could be reduced even in the most conservative scenarios of low process efficiency and high carbon intensity of the input power.This presentation will also cover the hurdles we have identified in the development of modular and continuously operated electrosynthetic reactors, as well as what we have learned in addressing these challenges.References(1) Saygin, D.; Gielen, D. Zero-Emission Pathway for the Global Chemical and Petrochemical Sector. Energies 2021, 14 (13), 3772. https://doi.org/10.3390/en14133772.(2) Gabrielli, P.; Rosa, L.; Gazzani, M.; Meys, R.; Bardow, A.; Mazzotti, M.; Sansavini, G. Net-Zero Emissions Chemical Industry in a World of Limited Resources. One Earth 2023, 6 (6), 682–704. https://doi.org/10.1016/j.oneear.2023.05.006.(3) Gross, S. The Challenge of Decarbonizing Heavy Industry, 2021. https://www.brookings.edu/wp-content/uploads/2021/06/FP_20210623_industrial_gross_v2.pdf.

Electrolytic Regeneration of Spent Caustic Soda from CO2 Capture Systems

The traditional electrochemical caustic soda recovery system uses the generated pH gradient across the ion exchange membrane for the regeneration of spent alkaline absorbent from CO2 capture. This electrochemical CO2 capture system releases the by-products H2 and O2 at the cathode and anode, respectively. Although effective for capturing CO2, the slow kinetics of the oxygen evolution reaction (OER) limit the energy efficiency of this technique. Hence, this study proposed and validated a hybrid electrochemical cell based on the H2-cycling from the cathode to the anode to eliminate the reliance on anodic oxygen generation. The results show that our lab-scale prototype enabled effective spent caustic soda recovery with an electron utilisation efficiency of 90%, and a relative carbonate/bicarbonate diffusional flux of approximately 40%. The system also enabled the regeneration of spent alkaline absorbent with a minimum electrochemical energy input of 0.19 kWh/kg CO2 at a CO2 recovery rate of 0.7 mol/m2/h, accounting for 30% lower energy demand than a control system without H2-recycling, making this technique a promising alternative to the conventional thermal regeneration technology.

Experimental study on optimum performance of two-stage air-heated bubble-column humidification–dehumidification system

An experimental investigation of a small-scale air-heated humidification–dehumidification (HDH) desalination system with bubble-column humidification and dehumidification units was conducted. The study addressed the performance of the multistage air-heated bubble-column HDH system, which has limited coverage in the literature, by operating two bubble-column humidifiers in series for the air humidification process with air reheating. The effect of operating parameters such as airflow rate, air temperature, and saline water levels in both humidifiers on the performance metrics of the system were investigated. The product distillate rate, energy consumption, gain output ratio (GOR), and specific energy consumption (SEC) are the main indicators of performance for the proposed desalination system. Response surface methodology (RSM) was applied to the current system using the design of experiment (DoE) for the prediction of variables that greatlyaffect productivity and energy input. The airflow rate, air temperature, and water level of the second humidifier have a favourable effect on the distillate rate and GOR of the system. In contrast, the effect of the water level inside the first humidifier is insignificant. Furthermore, the RSM optimization approach was used to obtain the optimum distillate productivity. An optimized distillate rate of 0.45 L/h and a GOR of 0.4 are achieved at 1.5 SCFM (standard cubic feet per minute) of airflow rate, and 6.5 cm of water level in the second humidifier with 140°C air inlet temperature. The numerical optimization reveals the optimal operating parameters, that correspond to maximum distillate production of 0.3 L/h with minimum input energy of 0.71 kW, to be 139°C air temperature, 1.13 SCFM of airflow rate, 6.5 cm and 3 cm water levels of second and first humidifier, respectively.

Blow-off of diffusion flame by moving air vortex ring

The blow-off is one of the typical flame extinction mechanisms, and such a principle has been widely used in firefighting when the water-based extinguisher is limited. This work explores the blow-off extinctions of different diffusion flames by air vortex ring. The vortex ring harnesses its kinetic energy within the fast-rotating vortex core, enabling the transmission of power over several meters to blow off a remote flame. The power required for vortex ring blow-off is found to be two to three orders of magnitude smaller than the power of the flame itself, demonstrating exceptional energy efficiency. It is observed that the poloidal flow (circulation) surrounding the vortex core can stretch the flame base to the critical state and then cause instantaneous extinction. To explain the vortex-induced blow-off limit, a critical Damköhler number that accounts for the competition between fuel gas flow and flame stretch was formulated. This work provides a fundamental understanding of the extinction mechanism by vortex ring, and it offers technical guidelines for using air as a flame extinguisher for remote firefighting within minimum energy input.

Optimization of cooling condition and energy parameters during laser bending of Duplex-2205

ABSTRACT In this study, the impact of process parameters on bend angle was explored under varying cooling conditions. Optimization of process parameters and cooling conditions was performed to maximize bend angle with minimum energy input. A regression fit function was generated and experimentally validated, and the mechanical and metallurgical properties at the optimum condition were analyzed. The study revealed that forced cooling at the lower surface significantly improved the bend angle, achieving a 35.2% increase compared to natural cooling. Process parameters were found to have varying effects at different cooling conditions. Optimization using Pareto front optimality and genetic algorithm resulted in a 7.5% increase in bend angle and a 22.14% improvement in bend angle per line energy rate. The tensile strength and hardness of the bend specimen at the optimum condition were increased at the expense of ductility, attributed to phase distribution rearrangement in the laser irradiation region.

State of art: Review on laser surface hardening of alloy metals

Surface hardening treatments are performed to increase the hardness, wear resistance, durability and their micro structural properties. After the development of High-Powered Diode Lasers (HPDL), the laser surface hardening process is widely applied due to their non-contact treatment process, rapid cooling without any medium, controlled method of heat treatment and depth with automation and precision with relatively minimum energy input. Laser surface hardening of steels, carbon alloys, iron and other metals in manufacturing of components, stamping and forging dies, tools and other components in the field of mechanical, automotive and metallurgical have shown a positive progression in hardness and wear resistance with controlled phase changes. The factors of laser power density and travel speed plays key roles in phase changes and the surface transformation hardening. The surface hardening of heavily loaded components under motion should possess good surface roughness, tribological characteristics of wear resistance, hardness and temperature coefficients. Thus, laser surface hardening is optimum, controlled and economic way of surface treatment processes in manufacturing of mechanical components.

Potential application of domestic solar dryers for coriander leaves: Drying kinetics, thermal efficiency, and quality assessment

AbstractCoriander (Coriandrum sativum L.) is a highly perishable crop with a shelf‐life of a few days under refrigerated conditions. Solar drying is one of the economical, hygienic and eco‐friendly methods of food preservation. During this study, fresh coriander was pre‐treated in a solution of 0.1% magnesium chloride, 0.1% sodium bicarbonate and 2.0% KMS for 15 min before solar or open sun drying. There were two types of solar dryers used, namely: PAU advanced domestic solar dryer and PAU domestic solar dryer. Solar dryers were evaluated and compared with open sun drying for drying kinetics, thermal efficiency, and product quality. The quality parameters determined were total color difference, total flavonoid content, total chlorophyll content, and ascorbic acid content. For drying of coriander, ADSD achieved the maximum thermal efficiency (18.56%) and minimum solar energy input (12.56 MJ/kg) out of the various drying systems under consideration. Additionally, ADSD samples had the highest quality retention in terms of the highest total flavonoid content (1.23 mg/100 g), total chlorophyll content (24.14 mg/100 g) and ascorbic acid content (24.29 mg/100 g).

Phase change material-enhanced solid-state thermoelectric cooling technology for food refrigeration and storage applications

In this work, a phase change material (PCM) enhanced thermoelectric (TE) Peltier module-based cooler has been proposed for the refrigeration and storage applications of the food industry. The proposed prototype used an organic PCM (product: RT 2HC; supplier: Rubitherm) with a melting temperature of 2 °C to provide passive cooling to maintain the temperature below 4 °C which is the typically recommended temperature for storage and transportation of perishable food items. The PCM will melt during the cooling of the food item. This allows for managing the energy demand, i.e., PCM will be discharged when it is needed for the system requirement. A detailed description of the manufacturing process of the prototype is presented. In the current study, different food items were tested in the manufactured prototype for cooling as well as to keep the temperature below 4 °C. Cost analysis and relative uncertainty calculation of the proposed prototype were performed. Mathematical modeling has been presented to calculate the amount of PCM required for the prototype. A comparative study was conducted between the commercially available cooler and the proposed system where the proposed system outperformed at maximum and minimum energy input. The proposed cooling system maintains a temperature below 4 °C for an infinite time at 11.4 W power input (6 V and 1.9A) and 26 h at a minimum power input of 4 W (3.1 V and 1.3A) in the ambient temperature of nearly 21 °C. The developed cooler could hold the temperature below 4 °C for nearly 7 h without any energy input. Moreover, the developed prototype has a COP of 0.75 at a temperature difference of 19 °C and a power input of 11.4 W. Furthermore, the life cycle assessment of the proposed system was conducted based on ISO 14040:2006(E) and it is found that the system emits 1170 kg CO2 and 1.04E-06 kg CFC-11 during 15 years of its lifetime.

A roadmap to enhance gas permselectivity in metal-organic framework-based mixed-matrix membranes.

Performing gas separation at high efficiency with minimum energy input and reduced carbon footprint is a major challenge. While several separation methods exist at various technology readiness levels, porous membrane-based separation is considered as a disruptive technology. To attain sustainability and required efficiency, different approaches of membrane design have been explored. However, the selectivity-permeation trade-off and membrane aging have restricted further advancement. In this regard, a new generation composite made of organic polymers and metal-organic framework (MOF) fillers shows substantial promise. Organic polymer matrix allows easy processibility, but it has poor permselectivity for gas molecules. Metal-organic frameworks are excellent sieving materials; however, they suffer from poor processibility issues. A combination of these two components makes an ideal sieving membrane, which can potentially outnumber the existing energy intensive distillation strategies. In this perspective, we have discussed key indices that regulate gas permselectivity by a careful selection of the existing literature. While the target gas flux and selectivity values have been a part of many previous reviews and articles, we have presented a concise discussion on the interface design of the MOF-polymer membrane, morphology, and orientation control of MOF fillers in the matrix. Following this, a future roadmap to overcome challenges related to MOF-polymer interfacial defects is outlined.

The joining of CP-vanadium and Ti–6Al–4V using the Electron Beam Melting Additive Manufacturing method

The use of electron beam welding for dissimilar welding (DW) of commercially pure (CP) vanadium to Ti–6Al–4V has been investigated via ARCAM S12, an additive manufacturing powder-bed system. Investigations of bead-on-plate welds for Ti–6Al–4V were first conducted to identify the process parameters for full penetration welds with a minimum energy input of 37 mA at a traverse speed of 7 mm/s. Vanadium bead on plate welds produced a penetration of approximately 75%, which was enough to proceed onto DW experiments. Defect-free full penetration welds were produced. The DW weld zone microstructure revealed an elongated dendritic structure comprised of bulky βTi grains and a fine substructure of α' laths. Thermal imaging (TI) showed an increment in radiance temperature ahead of the melt pool, indicating that there is a minimum energy required before keyhole welding is present, confirming mathematical calculations. Mechanical characterisation finds a fair range of hardness across both base metals (BM), heat affected zones (HAZ) and fusion zones (FZ). With no yield plateau in tensile test curves, the material is confirmed to fail on the side with lower mechanical properties, i.e., vanadium, which draws a fair process window for dissimilar welding between Ti6Al4V and vanadium alloys.

Evaluation of Four Tillage Methods Operating parameters by Overall index using Analytical Hierarchy Procedure and Compromise Programming Technique in the Gezira Heavy Clay Soils

This work was excuted during seasons 2018/2019, and 2019/2020, in Tayba Block-the Sudan - Gezira central clay plains, to evaluate the field operation performance of four land preparation methods using three tillage equipment: chisel plow "intensive tillage", disc harrow "medium tillage", ridger "minimum or reduced tillage" and no tillage machine. An overall operation index is estimated from four measured machine operating characteristics. Diagnosis of land preparation methods was made using analytical hierarchy method for weight assignment for assignment of relative weights for the operating parameters, and compromise programming technique for ranking of tillage methods. The experiment was conducted as a factorial experiment with RCBD, the LSD test at 1%and 5 % was used to compare between means. Results indicate that no significant differences (P<0.05) in field efficiency between Chisel plow and ridger and harrow showed the least efficiency value. There is significant differences in fuel consumption rate between all treatments with highest consumption is by Chisel plow and lowest is by ridger. The significantly highest rear wheel slippage is attained by ridger while there is no significant differences in that resulted from chisel or disc harrow. The significantly highest field capacity (P<0.05) is attained by ridger followed by harrow and then chisel plow. The analytical hierarchy procedure ranked the machines operation indicators in descending order by weight values of 1.02, 0.62, 0.29 and 0.12 for. Multi-criteria analysis by compromise programming technique results in overall indices of tillage equipments: ridger, chisel plow, disc harrow in descending values of 67.53, 61.00, and 57.29 respectively. The overall performance index (OPI) for the operation of the agricultural equipment could be used to take the tillage decision-making process by selecting the most effective machinery to give optimum seed bed with minimum energy input. However, it is not possible to calculate the overall index for no tillage method because without using a machine there is no fuel consumption, no field efficiency, no field capacity, and no wheel slippage. This imply that for heavy clay soils of Gezira Scheme and in other similar environments it is recommended to use reduced tillage "ridging only" as the most technically feasible tillage method, other wise use chisel plowing if funds are available.

Performance and duty types of lump peat machine moulding mill with regard to the final product quality

Wide-spreading of peat deposits allows long-term and promising production of lumpy peat for the purposes of energy generation, i.e. as a local municipal fuel, which, in turn, can reduce fuel shortage, especially in the non-gasified regions of Russia. The analysis of a small-size peat milling flowsheet, from the point of view of both energy cost saving and final product quality enhancement, allows development and expansion of the local municipal peat fuel production. During the study, the qualitative characteristics of small-size lumpy peat produced by moulding mill in various types of duty and the values of these characteristics at the minimum energy input are examined. To this effect, the peat strength testing procedure and machine are developed to simulate loading process similar to the real-life production conditions. The resultant values of lumpy peat strength and density are reflective of the efficient mode of moulding milling at the minimum energy input at the head coefficient of 2.22. A variant is proposed for the combination of design variables and duty types of the existing small-size lumpy peat machine moulding mills by the final product quality criteria, which should be taken into account in the machine design and operation. Small-size lumpy peat production in efficient duty modes ensures minimum energy input of milling at the required quality of the final product, and reduces losses of peat during milling. The proposed efficient duty types and design options of peat milling equipment can be correlated with this research findings in terms of lumpy peat machines that are both in operation and under design.

Research on Operation Optimization of LNG Submerged Pump System in LNG Receiving Terminals

This paper focuses on improving the operating efficiency of the Liquified Natural Gas (LNG) submerged pump system in the LNG receiving terminals and achieve energy saving. The minimum input energy consumption of the LNG submerged pump system is taken as the objective function, and an optimization model for the operation of the LNG submerged pump system with variable frequency speed is established. LINGO18.0 optimization software is used to solve the model to get the optimal LNG submerged pump operation plan that satisfies the constraints. Taking a certain LNG receiving terminal as an example, the operation optimization of its LNG submerged pump system is carried out, and the input energy consumption of the system before and after optimization is compared. The results show that the use of variable frequency pumps can reduce the energy consumption of the LNG submerged pump system of LNG receiving terminals, and the optimization model can reduce the input power consumption of the system by about 10% under different transportation conditions. After applying the optimization model to actual production, it is found that the model has certain practicability for guiding the production of LNG receiving terminal.

Design of clinched joints on the basis of binding mechanisms

The work carried out is based on the thesis properties of clinched joints are determined by the proportions of binding mechanisms form-closure, force-closure and material-closure. To describe the acting binding mechanisms and thus to derive the joint properties, detailed knowledge of the local effect of the individual binding mechanisms is necessary to ensure their targeted adjustment by the joining process. The targeted setting of different proportions of the binding mechanisms is achieved firstly via tool geometry and secondly via surface condition of the joined parts. An introduced form-closure component can be quantified by metallographic cross section with subsequent measurement of the quality-determining parameters such as undercut, penetration depth and neck thickness. To qualify the force-closure component, a torsional load can be applied mechanically at rotationally symmetrical clinch joints. This also allows the influence of different surface conditions on the tribological system to be quantified. Measurement of electrical resistance can reveal the binding mechanisms of force- and material-closure. These investigations are carried out on an aluminum joining part combination of the same type. As a result of these investigations, the clinched joints can be designed according to the load occurring in the later life cycle in the form of an optimum and compromise variant with regard to minimum loads to be transmitted mechanically, electrically with regard to low resistance or manufacturing with minimum energy input.

Prospects of algae-based green synthesis of nanoparticles for environmental applications

Green synthesis of nanoparticles (NPs) has emerged as an eco-friendly alternative to produce nanomaterials with diverse physical, chemical, and biological characteristics. Previously used, physical and chemical methods involve the production of toxic byproducts, costly instrumentation, and energy-intensive experimental processes thereby, limiting their applicability. Biogenic synthesis of nanoparticles has come forward as a potential alternative, providing an eco-friendly, cost-effective, and energy-efficient approach for the synthesis of a diverse range of NPs. Several biological entities are employed in the biosynthesis of NPs including bacteria, fungi, and algae. However, the distinguishing characteristics of microalgae and cyanobacteria make them promising candidates for NPs synthesis because of their higher growth rate, substantially higher rate of sequestering CO2, hyperaccumulation of heavy metals, absence of toxic byproducts, minimum energy input, and employment of biomolecules (pigments and enzymes) as reducing and capping agents. Algal extract, being a natural reducing and capping agent, serves as a living cell factory for the efficient green synthesis of nanoparticles. Physiological and biological methods allow algal cells to uptake heavy metals and utilize them as nutrient source to generate biomass by regulating their metabolic processes. Despite their enormous potential, studies on the microalgae-based synthesis of nanoparticles for the removal of toxic pollutants from wastewater remained an unexplored research area in the literature. This review was aimed to summarize the recent advancements and prospects in the algae-based synthesis of nanoparticles for environmental applications particularly treating the wastewater.

Physical Processes in the Thermal Vacuum System

Physical processes occurring during dehydration of heterogeneous materials in a thermal vacuum system have been analyzed. It has been demonstrated that the thermal-vacuum method provides dehydration and simultaneous wet-stock dispersion due to thermal diffusion, shock-wave and ionization effects, thereby leading to formation of novel-type nanodispersed material at minimum energy input. In recent years the intensification of production processes, as well as the solution of energy- and resource-saving problems have taken on great significance. For the sake of dehydration working-cycle improvement, combination of several process procedures in a single installation is used, resulting in both the intensification of the production process and the reduction in capital expenditures. There are the facilities, where the simultaneous use of mechanical grinding operation and the drying process is practiced. In this case, a preheated air is used as a drying agent, and this considerably increases the energy demands of the technological process. This phenomenon is attributed to the impact action and friction of material particles against grinding surfaces of the mill, to the appearance of new surfaces at crushing, and also, to the dust-gas mixture turbulence in the mill working area. That requires substantial power consumption and prevents from obtaining the product with desirable indicators, in particular, the with dispersion and moisture content, which substantially affect the quality of materials produced from fine-grained products. The analysis of fine grinding methods has shown that the most rational method of material grinding is the combination of impact loads. The impact loads facilitate the structure destruction of wet stock, while the abrasion loads acting in the field of high turbulent flows lead to the material destruction. The aim of the present work has been to define the physical processes in the thermal vacuum system, which can efficiently provide dehydration along with simultaneous dispersion of wet material, yielding a dried and ground feedstock in a short span of time.

Numerical study on performance of a hybrid indirect evaporative cooling heat recovery heat pump ventilator as applied in different climatic regions of China

Indirect evaporative cooling (IEC) and heat recovery are key technologies for decarbonising heating, ventilation, and air-conditioning (HVAC) while their performance is affected by the ambient environment. This paper presents a numerical investigation of a recently developed hybrid ventilator integrating the IEC and heat recovery. A TRNSYS-Matlab model was used to evaluate the ventilator's adaptability (operational and energy performance) in a public building at five typical cities in China. According to the validated model analysis, the ventilator shows a superior adaptability to the temperate region, with the lowest annual energy use at 96.70 kWh/m2 and the minimum energy input of the auxiliary source at 39.29% of the total energy use. The hybrid ventilator's adaptability is followed by the hot summer cold winter region and cold region where the ventilator covers 85% of the total heating/cooling loads in transition seasons. The severe cold region and hot summer warm winter region requires a significant auxiliary energy use for the stable indoor air parameters, which consumes 70.64% and 60.1% of the annual energy use, respectively. Future works are to improve the performance of the IEC and heat pump unit in the two climatic regions for better adaptability of the ventilator.

Bio-energetics of black gram (Phaseolus mungo) as influenced by different weed control practices

A field investigation was carried out during kharif season in 2010 at Agronomy Department Farm,Dr.Panjabrao Deshmukh Krishi Vidyapeeth, Akola, to evaluate the energy inputs, energy output, net energy gain and output input ratio of different weed control practices in black gram. It is observed that in herbicidal treatments, pre-emergence application of pendimethalin @ 1.5 kg/ha followed by cultural treatment of two hand weedings at 15 and 30 days after sowing recorded more energy inputs, while weedy check treatment incurred minimum energy input among all the treatments. Whereas, weed free treatment computed maximum energy output and energy balance followed by pre-emergence application of pendimethalin @ 1.5 kg/ha treatment. Similarly weed free and post emergence application (15 DAS) of fenoxyprop-p-ethyl @ 0.125 kg/ha were resulted in higher energy balance per unit input and output-input ratio than weedy check treatment.

Flying Squirrel-Inspired Motion Control of a Light-Deformed Pt-PAzoMA Micromotor through Drag Force Manipulation.

Micromotors require stable and precise motion control for complex tasks such as microsurgery, drug delivery in vivo, or environmental monitoring ex vivo. However, a continuous control signal is needed for micromotors to achieve motion control during their whole journey, which hinders their application in areas where external control stimuli are limited or unavailable. Fortunately, nature suggests an excellent solution that flying squirrel exhibits motion tuning capability by deforming itself when jumping off a tall tree. Inspired by this, we propose a Pt-PAzoMA Janus micromotor that precisely changes its shape (from a spherical shape to an elliptical shape) under a brief light signal (450 nm) and maintains this deformation until next signal reception. The deformed elliptical micromotor performs relatively low-speed motion compared to the spherical one, which is further confirmed by massive simulation results. In addition, by investigating motion behavior experimentally and theoretically, it is proved that the motion modulation is caused by the drag force changing brought from the deformation. This method represents a different route to regulate the motion of micromotors without a continuous signal, which is useful in application scenarios where the environmental control signal is inaccessible/limited or long-time operation with minimum energy input is required to maintain motion manipulation. With further function modification, this kind of shape-changing micromotor has potential in optimizing drug diffusion efficiency by speed altering and long-term monitoring at the diseased area by confining the active range of the micromotor in the targeted area through deformation.

Long term evaluation of a pilot scale multimodal algal bioprocess for treatment of municipal wastewater

The feasibility of Multimodal Algal-bacterial Bioprocess (MAB) for the treatment of primary clarified municipal wastewater was demonstrated at a pilot-scale MAB system (0.2 m3/d) installed and operated in Corvallis, Oregon, USA for one year. The system consisted of an anaerobic reactor; mixotrophic and phototrophic ponds followed by algal settlers and a final wetland cell (WC). The wastewater treatment performance was monitored weekly over the one-year period in terms of onsite parameters as pH, dissolved oxygen (DO), oxidation reduction potential (ORP), electrical conductivity (EC), total dissolved solids (TDS),turbidity and chemical parameters (COD, Nitrate-N, Amm.-N and reactive phosphorus). Algal biomass production and algal community analysis in the MAB was determined regularly. A continuous improvement in the mean DO (1.57–13.98 mg/L) and ORP (−140 to +86 mV) was observed throughout the study period. Higher mean pH (8.62) and DO (14 mg/L) in the ponds indicated high algal photosynthesis. The pilot-scale system maintained an average low final effluent turbidity (14.2 NTU), TSS (<30 mg/L) and COD concentrations (~78.3 mg/L) and achieved removal of nitrogen as Amm.-N (76%) and Nitrate-N (34%), phosphorus (DRP: 51%) throughout the experimental period. Particularly in summer, the overall treatment performance was high (70% COD removal; 78% Amm.-N removal; 38% Nit.-N removal; 53% DRP removal) owing to high algal-bacterial activity. The community analysis showed a predominance of diatoms and cyanophycean members in the winter and chlorophycean members especially species Chlorella (~80%) during summer. The average biomass productivities (VSS) in the treatment ponds ranged from 6.75 g/m2/d during winter to 11.47 g/m2/d during summer. Overall, the MAB can effectively treat municipal wastewater; produce quality final effluent and algal bioproducts with minimum energy inputs.