MFCs as biosensor, bioreactor and bioremediator

One of the most important challenges for our society is providing powerful devices for renewable energy production. Many technologies based on renewable energy sources have been developed, which represent a clean energy sources that have a much lower environmental impact than conventional energy technologies. Nowadays, many researches focus their attention on the development of renewable energy from solar, water, organic matter and biomass, which represent abundant and renewable energy sources. This research is mainly focused on the development of promising electrode materials and their potential application on emerging technologies such as artificial photosynthesis and microbial fuel cell (MFC). According to desired proprieties of functional materials, this research was focused on two main materials: (1) TiO2 for the development of electrodes for the water splitting reaction due to its demonstrated application potential as photocatalyst material and (2) carbon-based materials for the development of electrodes for MFC. In the first part of the investigation, different TiO2 nanostructures have been studied including: synthesis, characterization and test of TiO2-based materials with the aim of improving the limiting factors of the photocatalytic reaction: charge recombination and separation/migration processes. The photo-catalytic properties of different TiO2 nanostructures were evaluated including: TiO2 nanoparticles (NPs) film, TiO2 nanotubes (NTs) and ZnO@TiO2 core-shell structures. Photo-electrochemical activity measurements and electrochemical impedance spectroscopy analysis showed an improvement in charge collection efficiency of 1D-nanostructures, related to a more efficient electron transport in the materials. The efficient application of both the TiO2 NTs and the ZnO@TiO2 core-shell photoanodes opens important perspectives, not only in the water splitting application field, but also for other photo-catalytic applications (e.g. photovoltaic cells, degradation of organic substances), due to their chemical stability, easiness of preparation and improved transport properties. Additionally, in order to improve the photo-catalytic activity of TiO2 NPs, PANI/TiO2 composite film was synthesized. PANI/TiO2 composite film was successfully applied as anode material for the PEC water splitting reaction showing a significant increase in the photocatalytic activity of TiO2 NPs composite film essentially attributed to the efficient separation of the generated electron and hole pairs. To date, no cost-effective materials system satisfies all of the technical requirements for practical hydrogen production under zero-bias conditions. For this propose, to promote the sustainability of the process, the bias require to conduct PEC water splitting reaction could be powered by MFC systems in which many efforts have been done to improve power and electricity generation as is explained below. In this work, different strategies were also applied in order to improve the performance of anode materials for MFCs. The investigation of commercial carbon-based materials demonstrated that these materials, normally used for other ends are suitable electrodes for MFC and their use could reduce MFC costs and improve the energy sustainability of the process. In addition, to enhance power generation in MFC by using low-cost and commercial carbon-based materials, nitric acid activation (C-HNO3) and PANI deposition (C-PANI) were performed on commercial carbon felt (C-FELT) in order to increase the performance of MFC. Electrochemical determinations performed in batch-mode MFC reveled a strong reduction of the activation losses contribution and an important decrease of the internal resistance of the cell using C-HNO3 and C-PANI of about 2.3 and 4.4 times, respectively, with respect to C-FELT. Additionally, with the aim of solvent different MFC operational problems such as: biofouling, low surface area and large-scale MFC, an innovative three-dimensional material effectively developed and used as anode electrode. The conductive carbon-coated Berl saddles (C-SADDLES) were successfully used as anode electrode in batch-mode MFC. Electrochemical results suggested that C-SADDLES offer a low-cost solution to satisfy either electrical or bioreactor requirements, increasing the reliability of the MFC processes, and seems to be a valid candidate for scaled-up systems and for continuous mode application of MFC technology. In addition, the electrochemical performance and continuous energy production of the most promising materials obtained during this work were evaluated under continuous operation MFC in a long-term evaluation test. Remarkable results were obtained for continuous MFCs systems operated with three different anode materials: C-FELT, C-PANI and C-SADDLES. From polarization curves, the maximum power generation was obtained using C-SADDLES (102 mW•m-2) with respect to C-FELT (93 mW•m-2) and C-PANI (65 mW•m-2) after three months of operation. The highest amount of electrical energy was produced by C-PANI (1803 J) with respect to C-FELT (1664 J) and C-SADDLES (1674 J). However, it is worth to note that PANI activity was reduced during time by the operating conditions inside the anode chamber. In order to demonstrate the wide application potential MFC, this work reports on merging heterogeneous contributions and combining the advantages from three separate fields in a system which enables the ultra-low-power monitoring of a microbial fuel cell voltage status and enables pressure monitoring features of the internal conditions of a cell. The solution is conceived to provide an efficient energy source, harvesting wastewater, integrating energy management and health monitoring capabilities to sensor nodes which are not connected to the energy grid. Finally, this work presented a general concept of the integration of both devices into a hybrid device by interfacing PEC and MFC devices (denoted as PEC-MFC), which is proposed to generate electricity and hydrogen using as external bias the potential produce by microbial fuel cell

The use of wireless multimedia sensor networks (WMSNs) for surveillance applications has attracted the interest of many researchers. As with traditional sensor networks, it is easy to deploy and operate WMSNs. With inclusion of multimedia devices in wireless sensor networks, it is possible to provide data to users that is more meaningful than that provided by scalar sensor-based systems alone; however, producing, storing, processing, analyzing, and transmitting multimedia data in sensor networks requires consideration of additional constraints, including energy, processing power, storage capacity, and communication. Furthermore, as multimedia sensors produce much more data than scalar sensors, more manpower is required to analyze multimedia data. To overcome these constraints and challenges, this paper aimed to propose a system architecture and a set of procedures for WMSNs that facilitate automatic classification of moving objects using scalar and multimedia sensors. Methods and standards for detecting and classifying a moving object, as well as transmission of the results, are described in detail. The hardware for each sensor node includes a built-in camera, a passive infrared motion sensor, a vibration sensor, and an acoustic sensor. An application using our proposed methods was developed and embedded in the multimedia sensor node. In addition, a sink station was set up and the data produced by the sensor network was collected by this server. The classification performance of the application was tested using video recorded by the sensor node. The effect of the proposed methods on power consumption was also tested and measured. The experimental results show that the proposed approach is sufficiently lightweight to be used for real-world surveillance applications.

Microbial Fuel Cells (MFCs) are innovative environmental engineering systems that harness the metabolic activities of microbial communities to convert chemical energy in waste into electrical energy. However, MFC performance optimization remains challenging due to limited understanding of microbial metabolic mechanisms, particularly with complex substrates under realistic environmental conditions. This study investigated the effects of substrate complexity (acetate vs. starch) and varying mass transfer (stirred vs. non-stirred) on acclimatization rates, substrate degradation, and microbial community dynamics in air-cathode MFCs. Stirring was critical for acclimating to complex substrates, facilitating electrogenic biofilm formation in starch-fed MFCs, while non-stirred MFCs showed limited performance under these conditions. Non-stirred MFCs, however, outperformed stirred systems in current generation and coulombic efficiency (CE), especially with simple substrates (acetate), achieving 66% CE compared to 38% under stirred conditions, likely due to oxygen intrusion in the stirred systems. Starch-fed MFCs exhibited consistently low CE (19%) across all tested conditions due to electron diversion into volatile fatty acids (VFA). Microbial diversity was higher in acetate-fed MFCs but unaffected by stirring, while starch-fed MFCs developed smaller, more specialized communities. Kinetic analysis identified hydrolysis of complex substrates as the rate-limiting step, with rates an order of magnitude slower than acetate consumption. Combined hydrolysis-fermentation rates were unaffected by stirring, but stirring significantly impacted acetate consumption rates, likely due to oxygen-induced competition between facultative aerobes and electrogenic bacteria. These findings highlight the trade-offs between enhanced substrate availability and oxygen-driven competition in MFCs. For real-world applications, initiating reactors with dynamic stirring to accelerate acclimatization, followed by non-stirred operation, may optimize performance. Integrating MFCs with anaerobic digestion could overcome hydrolysis limitations, enhancing the degradation of complex substrates while improving energy recovery. This study introduces novel strategies to address key challenges in scaling up MFCs for wastewater treatment, bridging the gap between fundamental research and practical applications to advance environmental systems.

Over the past few years, the devices in Wireless Sensor Networks (WSN) are growing exponentially due to the emergence of many sophisticated applications. This tremendous growth leads to serious security challenges, and the devices of WSN should be protected from various attacks. WSN can be configured dynamically without fixed infrastructure and the devices can be talked with one another in an ad-hoc manner. Due to the dynamic nature of WSN, routing is considered as the challenging task that should be performed efficiently with robust routing mechanism. Even though many routing schemes have been emerged for WSN, they are not well scalable in very large-scale environment. This work introduces multi path routing strategy, and the routing will be selected based on trusted nodes. First, the trusted nodes are identified using trusted metrics of each node in the network. These metrics are calculated based on the threshold value of nodes. Then, secure routing is established by isolating node capturing attacks from the path. The performance of the work is analyzed in terms of packet loss, computational time and throughput. The paper compares the performance with the state-of-the-art routing schemes such as EMBTR (Enhanced Multi Attribute Based Attack Resistance), TSRM (Trust based secure routing model), and TARF (Trust-aware routing framework for WSNs). The outcome of the simulation shows that the proposed scheme outperforms the other state-of-the-work in terms of computational cost, throughput, and delay.

SummaryWith the rapid increase in energy utilization and the tremendously growing number of connected devices in wireless sensor networks (WSNs), alternate power transfer methods have not only become significant for scholastic purposes but also the growth of WSNs and the reduction of operational costs. Simultaneous wireless information and power transfer (SWIPT) is an emerging technology that has the potential to boost the lifespan of WSNs. This work presents an innovative approach to improving the energy efficiency of WSNs. Here, a WSN is considered, and energy‐aware communication is established in six phases, such as setup, steady state, energy prediction, SWIPT‐based power transfer, communication/route discovery, and route maintenance. Further, a hybrid approach named tangent sine search optimization (TSSO) is created to identify the ideal node as cluster head (CH). Later, the age of the neighboring nodes is forecasted utilizing the deep long short‐term memory (DLSTM), whose trainable parameters are selected using the proposed TSSO algorithm. A SWIPT‐based power transfer is also performed for harvesting the energy to avoid node failures. The proposed TSSO‐DLSTM+SWIPT is investigated given various metrics, like delay, residual energy, throughput, and trust, and the values attained are 0.784 s, 0.790 J, 0.970 Mbps, and 0.997, respectively without any attacks. The proposed TSSO‐DLSTM+SWIPT obtained performance improvement of 11.08%, 10.07%, 7.99%, and 5.83% than the Iterative algorithm in terms of delay, residual energy, throughput, and trust.

Amalgamation of low power IoT devices in Wireless Sensor Networks (WSNs) has enhanced the usage of WSNs as it lessens the requirements of total power consumption. Most such IoT devices comparatively employ short-range radio access technologies such as Bluetooth Low Energy (BLE) to transfer sensor data. When a WSN is situated in a remote region such that neither regular human monitoring is plausible nor Internet coverage is readily available, it requires an alternative method to gather data from sensor nodes. Hence, in this research, an attempt was made to improve the data collection process and monitor the parametric performance of a low power IoT WSN aided by an Unmanned Aerial Vehicle (UAV). The impact of physical parameters related to different sensor node arrangements was investigated to effectively utilize the total flying time of the drone. Subsequently, adjustments were proposed for improvements by referring to previous literature. The Hamiltonian path defined in Graph Theory was applied to reduce the traverse distance of the drone further by tracing the sensor nodes within the grid area systematically. A prototype was implemented using commercially available devices to demonstrate the feasibility and the functionality of the proposed solution. Our results show that the proposed system increases the data collection performance by 23% compared to referenced architecture.

Food waste is primarily managed by incineration or disposal in landfills. These current management methods can result in adverse environmental effects, are expensive, and do not necessarily take advantage of the remaining energy potential in food waste. Alternative treatment technologies such as microbial fuel cells (MFCs) are an attractive disposal method since overall organic concentrations can be reduced, and some of the chemical energy of the food waste can be transformed into electrical energy. MFC research has focused on the use of liquid waste due to advantages such as easy handling, low internal resistance, and efficiency of ion transfer in the liquid phase. While some researchers have shown the potential of using complex solid waste as a direct fuel in MFC, there remain significant challenges for optimizing complex solid food waste-fed MFCs. In particular, the biological degradation of the complex substrates in food waste is a slow process and requires additional pre-treatment (physical, thermal, chemical, or biological) to degrade complex biopolymers efficiently. As such, this article aims to review the impact and importance of various pre-treatment methods for optimizing performance of food waste fed MFCs. It is clear that direct use of solid waste in MFCs can be promising if several factors are optimized, including the pre-treatment used, substrate biodegradability, and operational cost. Although low power output is one of the main obstacles in the commercialization of MFC, MFC can still be considered a viable, self-sufficient treatment method to treat waste with minimum to zero emissions.

Sustainable strategy on microbial fuel cell to treat the wastewater for the production of green energy

Microbial fuel cell (MFC) technology is considered one of the renewable sources of energy for the production of bioelectricity from waste. Due to the depletion of fossil fuels and environmental considerations, MFC haa garnered increasing importance as it is a sustainable and environmentally-friendly method of generation of bioenergy. In MFC, electroactive bacteria (EAB) and biofilms are harnessed to convert organic substances to electrical energy. Extremophiles survive in extreme environments, and they have demonstrated potential applications in microbial electrical systems (MES) and MFC technology. The key limitations of MFC are the low power output and engineering constraints of the fuel cell. Hence, it is imperative to understand the genetics, key metabolic pathways, and molecular mechanisms of the EAB for enhancing the power generation in MFC. This chapter gives a brief overview of the scope and applications of extremophiles in wastewater treatment, bioelectricity, and biohydrogen production using MFC, eventually enhancing the functional efficiency of MFC.

Microbial fuel cells (MFCs) generate electricity using bacteria to degrade something and produce current, which have gained much attention. Harmful algae blooms(HABs) in lakes and rivers are on the increase all over the world, which becomes a more and more serious problem in the field of environment. In this study, algae MFCs(the main bacteria of MFCs were algae) were constructed and measured. The maximum voltage and current of a single algae MFC was 1.1V and 2.0mA, respectively. The minimum voltage and current of a single algae MFC was 0.1V and 0.3mA, respectively. Anode, cathode material, kind of bacteria, cathode solution(electroyte) had some influence on power densities of algae MFCs. The algae MFCs can generate enough electricity power densities to make an self-made electric fan spinning and self-made horse race lamp shinning. The use of algae MFCs not only generated electric energy but also may controll harmful algae blooms and optimiz water resource to some extent.

Node positioning accuracy and the environmental impact on devices in wireless sensor networks (WSN) have been paid attention much by scholars recently. This paper proposed a prediction method for the sensor node positioning based on a multilayer perception in the neural networks. The node locations based on its signals’ strength characteristics are captured to be a dataset. The features about the signal strength of the node considered to extract from a large number of signal strength samples included noise that is measured by the nearest neighbor estimation for inputs of the scheme system. The experimental results compared with the other method in the literature shows that the proposed scheme provides higher positioning accuracy and the lower average error than the competitors.

As the devices in Wireless Sensor Networks (WSNs) are small in size, and have resource constraints such as memory utilization, power consumption, and processing speed that needs to be taken in consideration. The security and life span of sensor nodes is compromised with these restraints. The purpose of this paper is to assess the performance of the Secure Force algorithm on an 8-bit microcontroller and analyze its execution time for variable data size. As compared to existing symmetric cryptographic algorithms, SF has simple architecture, and consists of basic mathematical operations that reduce the computational complexity. The proposed implementation is then compared with various microcontroller implementations of Advanced Encryption Algorithm (AES) on the basis of encryption time and memory utilization for variable data size.

Continuous improvement in hardware design and advances in wireless communication have enabled the deployment of various wireless sensor applications. Though, sensor nodes are highly resource constrained in terms of limited processing speed, runtime memory, persistent storage, communication bandwidth and finite energy. Flash memory has become a more widespread storage medium for modern wireless devices because of its effective features like nonvolatility, small size, light weight, fast access speed, shock resistance, high reliability and low power consumption. Even though flash memory offers many advantages, its special hardware read, write and erase characteristics impose design challenges on storage systems. This survey analysis the flash based storage management techniques proposed for resource constraint sensor devices, in terms of data life, device life, energy, and storage efficiency. Comprehensive simulation results show gradually improved performance in area of wireless sensor networks.

Cultivating eco-advantages: Unleashing the distinctive potential of biochar in microbial fuel cells

Microbial fuel cells (MFCs) have attracted attention by directly converting the bioelectrochemical energy possessed by the organic materials that make up the biomass into electrical energy. In this study, the relationship between the biofilm formed on the titanium-based anode electrode surface, and the chemical composition of the substrate, the energy source of MFC, was investigated. For this, MFCs were made by using poplar wood shavings rich in organic material as the substrate, titanium-based material as the anode electrode, and natural soil as bacterial habitat. Three types of MFCs containing 1%, 10%, and 20% poplar wood shavings by weight were made and named P1-MFC, P2-MFC, and P3-MFC, respectively. According to electrochemical analysis, P3-MFC provided the highest open circuit voltage with 490 mV value, and the highest power density with 5.11 mW/m2 value compared to other MFCs. According to optical microscopy examinations, there were Bacillus and Coccus species of bacteria in the soil structure, and these bacteria also existed around the fiber of poplar wood shavings in MFCs. Scanning electron microscopy (SEM), energy-dispersive spectrum (EDS), and Fourier transform infrared spectroscopy (FTIR) analysis showed that MFCs formed biofilm in the titanium-based anode, and the chemical composition of this biofilm with poplar tree was similar. As a result, due to the catalysis reactions of bacteria, the titanium-based anode electrode surface was coated with polymer biofilm released from poplar wood shavings.