Stable Operation Period Research Articles

The Future Development of Hong Kong Dollar Exchange Rate Regime

In the context of the developing economies, this paper examines the future outlook of Hong Kong's Linked Exchange Rate System. There is an emerging need for a re-evaluation of the system after a 40-year stable period of operation. This paper adopts a qualitative analysis to evaluate the current merits and dilemmas of the Hong Kong Dollar and its link with the Renminbi. It examines the possibility of pegging the Hong Kong Dollar to the Renminbi and the pre-conditions to be met for implementation. As well as the implications of such reform for both Hong Kong and the Mainland.

Achieving ultra-high nitrogen and phosphorus removal from real municipal wastewater in a novel continuous-flow anaerobic/aerobic/anoxic process via partial nitrification, endogenous denitrification and nitrite-type denitrifying phosphorus removal

Achieving economic and efficient removal of nutrients in mainstream wastewater treatment plants (WWTPs) continues to be a challenging research topic. In this study, a continuous-flow anaerobic/aerobic/anoxic system with sludge double recirculation (AOA-SDR), which integrated partial nitrification (PN), endogenous denitrification (ED) and nitrite-type denitrifying phosphorus removal (nDNPR), was constructed to treat real carbon-limited municipal wastewater. The average effluent concentrations of total inorganic nitrogen (TIN) and PO43−-P during the stable operation period were 1.8 and 0.3 mg/L, respectively. PN was achieved with an average nitrite accumulation ratio of 90.4 % by combined strategies. Adequate storage of polyhydroxyalkanoates and glycogen in the anaerobic zone promoted the subsequent nitrogen removal capacity. In the anoxic zone, nitrite served as the main electron acceptor for the denitrifying phosphorus removal process. Mass balance analysis revealed that nDNPR contributed to 23.6 % of TIN removal and 44.7 % of PO43−-P removal. The enrichment of Nitrosomonas (0.45 %) and Ellin 6067 (1.31 %), along with the washout of Nitrospira (0.15 %) provided the bacterial basis for the successful implementation of PN. Other dominant endogenous heterotrophic bacteria, such as Dechlormonas (10.81 %) and Candidatus Accumulibacter (2.96 %), ensured simultaneous nitrogen and phosphorus removal performance. The successful validation of integrating PN, ED and nDNPR for advanced nutrient removal in the AOA-SDR process provides a transformative technology for WWTPs.

Investigation of filtration performance and phosphorus removal in an electric field controlled dynamic membrane bioreactor

Dynamic membrane bioreactor (DMBR) offers several advantages over traditional membrane bioreactor, including cheaper costs, less resistance, and easier cleaning. Membrane fouling and poor phosphate removal performance restrict the application of DMBR. To address it, this study creatively combined electric field with DMBR and investigated the mechanisms. The results showed that applying an electric field significantly decreased membrane fouling rate in electric dynamic membrane bioreactor with Ti anode (E-DMBR-Ti). The median membrane fouling rate of E-DMBR-Ti was 2.28 kPa/h, which was 48.99 % lower than that of control group (4.47 kPa/h) during stable operation period. However, hydrogen bubbles formed on the cathode blocked membrane during membrane formation period. The enrichment of electroactive and denitrifying microorganisms (e.g., Lactococcus, Hydrogenophaga) in E-DMBR-Ti, which consumed electrons that would flow to the hydrogen evolution reaction, alleviated the negative impact. To address the issue of poor phosphorus removal efficiency of DMBR, based on the previous research, we replaced the titanium mesh of the anode with aluminum plates, and innovatively using the electrocoagulation technology which named E-DMBR-Al. At 2.4 A/m2 current density, E-DMBR-Al showed the highest phosphorus removal efficiency, with a median of 94.69 %, which was 37.69 % higher than that of DMBR. Furthermore, the enrichment of electroactive microorganisms (e.g., Lactococcus) and polyphosphate-accumulating organisms (e.g., unclassified_f__Comamonadaceae) on membrane contributed to the excellent phosphorus removal performance of E-DMBR-Al.

A Sewing Approach to the Fabrication of Eco/bioresorbable Electronics.

Eco/bioresorbable electronics represent an emerging class of technology defined by an ability to dissolve or otherwise harmlessly disappear in environmental or biological surroundings after a period of stable operation. The resulting devices provide unique capabilities as temporary biomedical implants, environmental sensors, and related systems. Recent publications report schemes to overcome challenges in fabrication that follow from the low thermostability and/or high chemical reactivity of the eco/bioresorbable constituent materials. Here, this work reports the use of high-speed sewing machines, as the basis for a high-throughput manufacturing technique that addresses many requirements for these applications, without the need for high temperatures or reactive solvents. Results demonstrate that a range of eco/bioresorbable metal wires and polymer threads can be embroidered into complex, user-defined conductive patterns on eco/bioresorbable substrates. Functional electronic components, such as stretchable interconnects and antennas are possible, along with fully integrated systems. Examples of the latter include wirelessly powered light-emitting diodes, radiofrequency identification tags, and temporary cardiac pacemakers. These advances add to a growing range of options in high-throughput, automated fabrication of eco/bioresorbable electronics.

Full-scale partial nitritation and anammox (PN/A) application in removing nitrogen from industrial wastewater: Performance and life cycle assessment

Anaerobic ammonium oxidation (anammox) is an innovative nitrogen removal process that is widely used in wastewater treatment due to its energy-saving potential and ability to reduce carbon emissions. However, research on the application of anammox in full-scale industrial wastewater treatment plants (WWTPs) is limited, and its environmental impacts are yet to be fully understood. This study evaluates the performance and environmental burdens of one-stage partial nitritation and anammox (PN/A) in a full-scale WWTP treating coal chemical wastewater, with different demonstration periods. Compared with conventional nitrification–denitrification, the energy footprint and carbon footprint of the PN/A process were significantly lower and effluent quality was improved. Based on the four-quadrant clustering method, the overall performance of the studied WWTP achieved the greatest synergy during the stable operation period. Life cycle assessment has shown that the PN/A process significantly reduces the system’s contribution to environmental indicators. According to the sensitivity analysis, the fluctuations in energy consumption and chemical usage have significant environmental impacts, with differential sensitivity in the environmental impacts of two demonstration periods. Therefore, considering the specific situation of the WWTPs, optimizing the parameters/indicators most sensitive to environmental impact is essential to reducing environmental loads. Importantly, this work demonstrated that PN/A can improve the operational performance of full-scale industrial WWTPs with lower environmental burdens, providing valuable guidance for the development of sustainable wastewater treatment processes.

Simultaneous phosphorus removal and sludge reduction in continuous-flow reactor with granules under long sludge retention time

The simultaneous phosphorus (P) removal and sludge reduction by extending the sludge retention time (SRT) in the continuous-flow reactor (CFR) with enhanced biological phosphorus removal (EBPR) granules were investigated in this study. While the system operated without sludge discharge for 60 days, the COD and P removal efficiencies and settling ability of granules deteriorated obviously. Meanwhile, the protein content increased and the sludge production reduced gradually during this period due to the decrease of PAOs activities. Then, some sludge was discharged every day during the day 61–180, and the performance of CFR and the settling ability of granules recovered gradually to an excellent level. The sludge production and sludge yield were 1.34 g day−1 and 0.11 gMLSS gCOD−1 during the recovery and stable operation period, respectively. Although about 60% sludge reduction was obtained, excellent P removal was demonstrated simultaneously. Hence, sludge minimization and excellent P removal were successfully coupled by extending SRT in CFR with EBPR granules. The results of Illumina MiSeq sequencing showed that the fermentative bacterium increased after extending the SRT, which played a key role in sludge reduction.

Anti-Counterfeiting and Traceability Consensus Algorithm Based on Weightage to Contributors in a Food Supply Chain of Industry 4.0

Supply chain management can significantly benefit from contemporary technologies. Among these technologies, blockchain is considered suitable for anti-counterfeiting and traceability applications due to its openness, decentralization, anonymity, and other characteristics. This article introduces different types of blockchains and standard algorithms used in blockchain technology and discusses their advantages and disadvantages. To improve the work efficiency of anti-counterfeiting traceability systems in supply chains and reduce their energy consumption, this paper proposes a model based on the practical Byzantine fault tolerance (PBFT) algorithm of alliance chains. This model uses a credit evaluation system to select the primary node and integrates the weightage to contributors (WtC) algorithm based on the consensus mechanism. This model can reduce the decline in the algorithm success rate while increasing the number of malicious transaction nodes, thereby reducing the computing cost. Additionally, the throughput of the algorithmic system increases rapidly, reaching approximately 680 transactions per second (TPS) in about 120 min after the malicious nodes are eliminated. The throughput rapidly increases as the blacklist mechanism reduces the number of malicious nodes, which improves the system’s fault tolerance. To validate the effectiveness of the proposed model, a case study was conducted using data from the anti-counterfeiting traceability system of the real-life supply chain of a food company. The analysis results show that after a period of stable operation of the WtCPBFT algorithm in the proposed model, the overall communication cost of the system was reduced, the throughput and stability were improved, and the fault-tolerant performance of the system was improved. In conclusion, this paper presents a novel model that utilizes the PBFT algorithm of alliance chains and the WtC algorithm to improve the efficiency and security of anti-counterfeiting traceability systems in supply chains. The results of the case study indicate that this model can effectively reduce communication costs, improve throughput and stability, and enhance the fault tolerance of the system.

Application of bio-slow sand filters for drinking water production: Linking purification performance to bacterial community and metabolic functions

Bio-slow sand filters (BSSFs) are widely employed in rural drinking water treatment ascribing to its economic applicability, easy operation and high efficiency. This study investigated the influence of particle size, filter thickness, water quality and filtration rate on decontamination performance, bacterial community and metabolic function of BSSFs. The effluent ammonia nitrogen during stable operation period basically met the standards for drinking water quality in China (0.5 mg/L). The average removal efficiencies of fine sand were about 4 % higher than those of coarse sand, and thick filter layer showed more stable performance. Schmutzdecke removed most turbidity and organic pollutants, playing an overwhelming role in water purification. Filtration rate was a key factor in shaping bacterial community structure. Proteobacteria and Cyanobacteria were dominant phyla, whose relative abundance significantly decreased and increased as filtration rate increasing, respectively. Co-occurrence patterns were dominant within bacterial communities. Function bacteria (e.g. Hyphomicrobium and Methylophilus) and rare genera (Curvibacter and Simplicispira) were identified as hub genera in the networks. The bacterial communities exhibited a metabolic versatility. Several pathways for secondary metabolism significantly shifted under different conditions, such as xenobiotics biodegradation and metabolism. Moreover, filtration rate and dominant genera greatly affected pollutant removal performance. Many species of Proteobacteria and Bacteroidota were closely related to carbohydrate metabolism, energy metabolism and nucleotide metabolism, and metabolic functions corresponded more cohesively to conditional abundant taxa, conditional rare or abundant taxa, conditional rare taxa. This study highlights the adaptability and bacterial community characteristics of BSSFs, and provides references for their practical application.

Particle-In-Cell Simulations of High Efficiency 12-Vanes 2.45 GHz Continuous Wave Magnetron

As an essential vacuum electronic device for producing the microwave, the magnetron has various applications. This study developed a novel high-efficiency 12-vanes CW magnetron and anode resonance system that improved mode separation, expanded the working space of π-mode and made other modes more challenging to trigger, ultimately eliminating the possibility of mode jumping. A magnetron was simultaneously supplied with a particular quantity of anode voltage, and the cathode was generated by the electron, and high-frequency field interaction of a homogeneous magnetic field. The work efficiency of the 12-vanes CW magnetron was significantly enhanced. Given an anode voltage of 8000 V and a magnetic flux density of 3980 Gs as a consequence of particle simulation, the variation trend of a magnetron’s output power oscillation curve correlated with the development of hexagonal spokes. After a period of stable operation, the magnetron’s fundamental parameters were determined to be as follows: the primary frequency oscillation frequency was 2.466 GHz, the anode collision current was 1.08 A, the amplitude of sinusoidal oscillation was 125, the output power was 7812.5 W, and the corresponding power conversion efficiency was 90.42%. Changing the magnitude of the anode voltage or magnetic flux density resulted in a reduction in power conversion efficiency within a particular range; however, between 85% and 90% stability was maintained.

Analysis of energy recovery and microbial community in an amalgamated CSTR-UASBs reactor for a three-stage anaerobic fermentation process of cornstalks.

In this study, a continuous stirred-tank reactor (CSTR) coupled with up-flow anaerobic sludge beds (UASBs) reactor was successfully developed for enhancing methane production and carbon recovery rate from cornstalks. Acetic acid production was higher in regions A than in B and C. The methane percentage achieved at 75.98% of total gas and methane production of cornstalks was up to 520.07 mL/g, during the stable operation period. The carbon of recovery rate, represented substrates converted to methane gas, reached 69.32% in stable stage. Microbial community structure analysis revealed that Paludibacter, Prevotella/Clostridium sensu stricto, and Caldisericum were the dominant bacteria for the degradation of cellulose, lignin, and other refractory macromolecules in regions A, B, and C, respectively. Methanobacterium and Methanolinea were the two major genera, accounting for methanogenesis generation.

Rapidly achieving partial denitrification from nitrate wastewater in a alkaline fermentation system with primary sludge as inoculated sludge and fermentable substrate

In order to promote practical engineering application of anaerobic ammonium oxidation(anammox) process, reduction of primary sludge(PS) in wastewater treatment plants(WWTPs) and removal of nitrate contaminant, a single-stage simultaneous alkaline fermentation coupled with partial denitrification(SAFPD) system was established successfully in this study. Nitrite production was rapidly achieved from nitrate wastewater with PS as inoculated sludge and fermentable substrate under anaerobic and anoxic operating conditions. During the stable operation period, the primary sludge reduction(PSR) and productivity of organic matters were 27.9% and 483.8mgCOD/gVSS, with nitrate removal of 90.7%, NO3– to NO2– transformation ratio(NTR) of 80.0%. After 125 days of acclimation, the relative abundance of Thauera, Dechloromonas and Candidatus_Competibacter increased from 0.17%, 0.02% and 0.05% to 11.58%, 4.28% and 5.6% respectively. Above results showed that this SAFPD system not only realized the reduction of PS and nitrate removal, but also laid a solid foundation for anammox process with its high nitrite production.

Substrate Characteristics Fluctuations in Full-Scale Anaerobic Digesters Treating Food Waste at Marginal Organic Loading Rates: A Case Study

The design of a full-scale bioprocess is typically based on parameters derived from smaller-scale experiments from a previous study. However, disagreements often occur at up-scaling of waste-to-energy processes due to the fluctuations of the substrate characteristics, etc. Therefore, once a commercial-scale waste digester has been built and operated, it is essential to test if the performance of the process agrees with its design value; during this process, fluctuations might occur in digesters operated at marginal organic loading rates. In this study, triplicate full-scale anaerobic digesters treating food waste were monitored for five months. The digesters, operated at the design feeding ratio, showed increasing volatile fatty acid (VFA) trends (per total alkalinity) due to a 30% higher chemical oxygen demand of the influent, than the design. The organic loading rate was adjusted on a daily basis until a stable performance was observed. Significant shifts of methanogen populations from Methanobacteriales to Methanomicrobiales and Methanosarcinales were observed during the stable operation period.

Transient Batteries: A Promising Step Towards Powering Green Electronics

Transient electronics is an emerging class of innovative technology wherein electronic devices undergo controlled degradation processes after a period of stable operation, leaving no toxic products behind. This technology offers exciting opportunities in research areas of green electronics, temporary biomedical implants, data-secure hardware systems, and many others. However, one major challenge with these devices is their rigid and bulky batteries that contain toxic chemicals and are not at all degradable. So, to realize autonomous and self-sufficient transient electronics, the development of transient batteries is a pre-requisite. This review provides an overview of the advancements in the field of transient batteries, their materials, output performance, transience behaviour, and a few potential applications.

The Impact of Berberine Pharmaceutical Wastewater on Aerobic Granules Formation: Change of Granules’ Size

As important parameters in the characterization of aerobic granulation, the shape and average diameter were related to substrates. The previous studies disclosed that the morphology change in aerobic granules was the result of growth and the relatively strong hydrodynamic shear force. No further exploration of the size distribution of the aerobic granules has been conducted. To better understand the impact of toxic compounds on aerobic granules’ growth during their formation, the properties of aerobic granules were traced over 81 days in 3 sequencing batch reactors fed with acetate and berberine wastewater, especially the particle size and size distribution. The results showed that the aerobic granules were cultivated by the simulated acetate wastewater (R1), simulated berberine wastewater (R2), and effluent from an anaerobic baffled reactor (ABR) reactor which was fed with industrial berberine wastewater (R3). The reactors exhibited different COD removal efficiencies, and the MLSS and MLVSS values affected by the different substrates which were in an order of R1 > R2 > R3. However, the SVI and SOUR, which were affected by several factors, showed more complicated results. The aerobic granules had the lowest microbial activity (SOUR), while the aerobic granules in R3 had the lowest settling ability among the three kinds of granules. For the three reactors with different influent compositions, the aerobic granulation process displayed a three-stage process separately. Compared with the granules fed with berberine wastewater, the granules fed with acetate in a stable operation period showed more independence from other periods.The size distribution was affected by substrates. The aerobic granules with a range of 0.3–1.0 µm occupied 77.0%, 67.0%, and 35.7% of the volume for R1, R2, and R3, respectively. The biomass less than 0.3 µm occupied 59.1% volume in R3. The components of the substrate had a great influence on the growth of aerobic granules, not only on the diameter but also on the size distribution.

Gravity-driven high flux filtration behavior and microbial community of an integrated granular activated carbon and dynamic membrane bioreactor for domestic wastewater treatment

A gravity-driven dynamic membrane bioreactors (DMBR) with GAC addition (G-DMBR) was operated under constant pressure filtration mode (using 20 cm water head) for real domestic wastewater treatment. During the stable operation period, the treatment performance, DM filtration behavior and mechanism as well as microbial properties were studied and compared with a control DMBR (C-DMBR). Both DMBRs showed stable removal of chemical oxygen demand (COD) and ammonia (NH4+-N) with average removal rates over 88% and 98%, respectively. GAC addition effectively enhanced dynamic membrane (DM) permeability with a stable flux of 17 to 65 L/m2h, which was approximately four times higher than that in the C-DMBR without GAC addition. Filtration resistance analysis indicated the DM formation can be divided to three stages: the formation of the initial DM layer, the development of mature DM layer and dynamic equilibrium stage of the DM layer. Filtration model analysis illustrated that added GAC could be the skeleton of the DM, resulting in a more porous and incompressible DM layer. Additionally, microbial community analysis revealed that in the G-DMBR several fouling-causing phyla including Proteobacteria reduced while other phyla preferring attached growth such as Bacteroidetes and Gemmatimonadetes increased. Thus, adding GAC to the DMBR can be an effective strategy for achieving stable and high-flux operation by modifying DM properties and regulating DM formation process and structure.

Diclofenac biotransformation in the enhanced biological phosphorus removal process

Diclofenac is a pharmaceutical active compound frequently detected in wastewater and water bodies, and often reported to be persistent and difficult to biodegrade. While many previous studies have focussed on assessing diclofenac biodegradation in nitrification and denitrification processes, this study focusses on diclofenac biodegradation in the enhanced biological phosphorus removal (EBPR) process, where the efficiency of this process for diclofenac biodegradation as well as the metabolites generated are not well understood. An enrichment of Accumulibacter polyphosphate accumulating organisms (PAOs) was operated in an SBR for over 300 d, and acclimatized to 20 μg/L of diclofenac, which is in a similar range to that observed in domestic wastewater influents. The diclofenac biotransformation was monitored in four periods of stable operation and linked to the microbial community and metabolic behaviour in each period. Nitrification was observed in two of the four periods despite the addition of a nitrification inhibitor, and these periods were positively correlated with increased diclofenac biodegradation. Interestingly, in two periods with excellent phosphorus removal (>99%) and no nitrification, different levels of diclofenac biotransformation were observed. Period 2, enriched in Accumulibacter Type II achieved more significant diclofenac biotransformation (3.4 μg/gX), while period 4, enriched in Accumulibacter Type I achieved lower diclofenac biotransformation (0.4 μg/gX). In total, 23 transformation products were identified, with lower toxicity than the parent compound, enabling the elucidation of multiple metabolic pathways for diclofenac biotransformation. This study showed that PAOs can contribute to diclofenac biotransformation, yielding less toxic transformation products, and can complement the biodegradation carried out by other organisms in activated sludge, particularly nitrifiers.

Rapidly achieving and optimizing simultaneous partial nitrification denitrification and anammox integrated process by hydroxylamine addition for advanced nitrogen removal from domestic wastewater

The achievement and stable maintenance of partial nitrification and partial anammox process for municipal sewage is a challenging research topic at present. In this study, a novel strategy of hydroxylamine (NH2OH) addition under low DO condition was adopted for rapidly achieving simultaneous partial nitrification denitrification and anammox process (SPNDA) to deal with domestic wastewater, the nitrite accumulation ratio (NAR) increased from 1% to 82% in the first 4 days. After the addition of NH2OH was stopped, the PN effect of SPNDA process remained relatively stable within 100 days. During the stable operation period with aerobic HRT of 5 h, the nitrogen removal efficiency was 87.9 ± 4.2%. Moreover, the abundance of denitrifying bacteria and Candidatus Brocadia increased from 1.79% and 0.062% to 22.49% and 0.38% respectively, which promoted nitrogen removal effect. Overall, this study provided a quickly way for achieving the cost-effective SPNDA process to enhance nitrogen removal with NH2OH addition.

Performance and microbial characteristics of a novel pilot-scale tubing biological contact oxidation reactor for rural drinking water

Drinking water treatment under rural conditions often require compactness and portability. To address this, the present study developed a pilot-scale helical tubular biological contact oxidation (BCO) reactor filled with annular porous biofilm carriers (fillers). To determine the drinking water treatment efficiency and microbial characteristics, the system was investigated for 212 days at (24.1 ± 3.4) °C under different flow rates (1.86 L · h−1, 3.72 L · h−1, and 7.2 L · h−1) to treat simulated rural drinking water. The results show that (62.7 ± 9.3) % of ammonium (NH4+-N) and (19.5 ± 5.4) % of UV254 absorbance were removed by the BCO reactor after entering the stable operation period. It is shown that shorter hydraulic retention time (HRT) weakened the removals of tryptophan-like substances and fulvic acid according to the three-dimension fluorescence excitation emission matrix spectroscopy, with the removal ratios decreased from 90% to 0% when the HRT declined from 16.8 h to 4.2 h. Despite operating at regular room temperature ((24.1 ± 3.4) °C), the drinking water BCO reactor underwent a long start-up period (5.5 months) to reach a steady state in terms of biofilm concentration and pollutant removal performance. Genus Xanthobacter and Methylobacterium might significantly contribute to the removal of NOM in the BCO reactor, while genus Pedomicrobium and Bradyrhizobium were speculated to be responsible for nitrogen conversion. The present study provides new insights into the application of BCO reactors for ammonium and NOM removal from rural drinking water.

Large‐Area Transient Conductive Films Obtained through Photonic Sintering of 2D Materials

AbstractTransient electronics that can chemically or physically disappear after a period of stable operation have been achieved through various metal and semiconductor materials. Despite excellent properties and wide availability of 2D materials and van der Waals (vdW) thin‐film electronics, transient films and devices based on them have rarely been reported, not to mention large‐area production with high throughput. Here, a photonic sintering approach is developed to achieve large‐area transient vdW films that may be used for bioresorbable devices. The approach can process 2D materials such as graphite, graphene, and transition metal sulfide, resulting in continuous films that are 10 × 10 cm2 in area and ≈60 to ≈440 nm in thickness on transient substrates. The influence of interfacial adhesion and sintering conditions to the thickness and the electrical properties of transient graphite films is investigated. In addition, the transient films can yield conductive patterns such as biopotential electrodes, interdigital electrodes, and resistor arrays using complementary metal–oxide–semiconductor (CMOS) fabrication processes or a two‐step sintering method. The photonic sintering method may eventually lead to large‐area transient electronics for innovative applications in healthcare, data security, and consumer electronics, and enrich the category of transient electronics through achievement of more printable transient vdW electronics.

Transient Rechargeable Battery with a High Lithium Transport Number Cellulosic Separator

AbstractTransient batteries play a pivotal role in the development of fully autonomous transient devices, which are designed to degrade after a period of stable operation. Here, a new transient separator‐electrolyte pair is introduced for lithium ion batteries. Cellulose nanocrystals (CNCs) are selectively located onto the nanopores of polyvinyl alcohol membranes, providing mobile ions to interact with the liquid electrolyte. After lithiation of CNCs, membranes with electrolyte uptake of 510 wt%, ionic conductivities of 3.077 mS·cm–1, electrochemical stability of 5.5 V versus Li/Li+, and high Li+ transport numbers are achieved. Using an organic electrolyte, the separators enable stable Li metal deposition with no dendrite growth, delivering 94 mAh·g–1 in Li/LiFePO4 cells at 100 mA·g–1 after 200 cycles. To make the separator‐electrolyte pair transient and non‐toxic, the organic electrolyte is replaced by a biocompatible ionic liquid. As a proof of concept, a fully transient Li/V2O5 cell is assembled, delivering 55 mAh·g–1 after 200 cycles at 100 mA·g–1. Thanks to the reversible Li plating/stripping, dendrite growth suppression, capacity retention, and degradability, these materials hold a bright future in the uptake of circular economy concepts applied to the energy storage field.