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The recent COVID-19 crisis necessitated the universal use of Personal Protection Equipment (PPE) kits, generating tons of plastic wastes that inevitably lead to environmental damage. Circumventing the challenges stemming from such undesirable non-degradability on disposal, here we present an eco-friendly, robust, yet inexpensive and equipment-free method of growing biodegradable PPE fabrics by the fermentation of locally-sourced organic feed stocks in a rural livelihood. Using a pre-acclimatized symbiotic culture, we report the production of a high yield (up to 3.2 g fabric/g substrate) of bacterial cellulose, a biopolymer matrix, obtained by bacterial weaving. This membrane has an intricate, self-assembled, nano-porous 3D architecture formed by randomly oriented cellulose fibres. Scanning electron microscopy reveals that the pore size of the membrane turns out to be in the tune of 140 nanometers on the average, indicating that it can filter out viruses effectively. In-vitro results demonstrate assured breathability through the membrane for a filter thickness of approximately 5 microns. When subjected to soil degradation, the fabrics are seen to disintegrate rapidly and fully decompose within 15 days. With a favourable cost proposition of less than 1 US$ per meter square of the developed fabric unit, our approach stands out in providing a unique sustainable, and production-ready alternative to synthetic PPE fabrics, solving community healthcare and environmental crisis, and opening up new avenues sustainable under-served livelihood at the same time.Graphical abstract

The rise in the global energy demands with the depleting fossil fuels has triggered the quest for the alternate renewable fuels. In this regard, hydrogen energy has emerged as a possible substitute for the fossil fuels and thus has gained tremendous research attention in the recent past. Hydrogen production through biological routes proves to be an attractive alternative as it is energy intensive and environment-friendly. The electromediated microbial electrolysis cells provide a new avenue for the production of biohydrogen from organic wastes. The key advantage of this technology is that a complete conversion of organic waste to hydrogen can be achieved theoretically unlike other biohydrogen technologies that are limited by their theoretical conversion efficiencies. This chapter provides an insight into the basics of microbial electrolysis cells and further explores the breakthroughs observed in this technology over the past few years and concludes with the future outlook of the process.

A series of fluorenyl and trifluoromethyl groups containing co-poly(ether imide)s (S-co-PIs) have been prepared from a new diamine monomer; 9,9-bis(3-methoxy-4-(4-amino(3-trifluoro-methyl)biphenoxy)phenyl)-9H-fluorene (APHPF). The polymers were prepared by the polycondensation reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) with two different diamines; APHPF and 4,4′-diaminostilbene-2,2′-disulfonicacid (DSDSA) as a co-monomer. The monomer and polymers were well characterized by 1 H NMR and ATR-FTIR spectroscopies. The co-polymers were soluble in various organic solvents and membranes were prepared from solution cast route. The S-co-PIs showed high thermal and mechanical stability. TEM and AFM results supports the formation of phase separated morphology with well separated ionic-clusters. All these S-co-PIs displayed reasonably high proton conductivity. One of the copolymers (DAN-80; IECw ∼2.27 meq g −1 ) exhibited a proton conductivity as high as 149 mS cm −1 which was comparable to that of Nafion® 117 (165 mS cm −1 ) at 80 °C. The co-polymers maintain a good balance between water-uptake and swelling ratios and peroxide resistance. Microbial Fuel Cell (MFC) performance of the co-polymers were evaluated DAN-80 exhibited a similar performance like Nafion® 117 under similar test condition.

Understanding the fundamental processes underlying the microbial fuel cells (MFCs) can provide valuable insights in recognizing the key limiting factors, the scope of improvement of the system which in turn helps in the scaling-up the process. The science behind an MFC is complex and it involves a subtle interplay of various fields such as microbiology, physics and electrochemistry (Zhang and Halme 1995). A comprehensive understanding of various parameters involved in the process is essential for the improvement of power generation and to explore further applications. Modelling the system prior to experimentation can provide various perspectives and alternatives saving time and money. The physics of the process can be understood using quantitative predictions using modelling. It also provides valuable information about the dynamics of a process and thus important in reactor design and scale-up. Consequently, efficient monitoring of the process as well as precise control may be achieved through modelling (Marcus et al. 2007). Multi-scale modelling is crucial for a well-defined understanding of the process at both micro and macro scales.

Microbial fuel cells (MFCs) are being studied as a biosensor for a wide gamut of applications. Currently, since the power generated by an MFC is too low to power any practical devices, it is pertinent to use MFC as a sensor for the accurate and simple measurement of various analytes. The present chapter deals with the various upcoming applications of the MFC technology in the field of sensing with an emphasis on Biochemical Oxygen Demand (BOD) bio-sensing. The application of MFCs as BOD biosensor is one of the most widely studied fields followed by the volatile fatty acid sensing and toxicity sensing. Figure 20.1 depicts various novel applications of MFC as biosensor from the literature.

Microbial fuel cells (MFCs) are renewable sustainable technologies that can convert biodegradable wastes directly into electricity. This conversion is usually brought about by electrogenic bacteria that can degrade the organic/inorganic substrates via their metabolisms and transfer the released electrons to a solid electron acceptor (the electrodes). A typical MFC comprises different components such as an anode, a cathode, a separator, electrolyte and electrical circuits. Each of these components have pivotal role in depicting the overall performance of MFCs. At present, the power outputs of MFCs are too low which restricts its practical applicability. To overcome the bottlenecks, a better understanding of all the components and their limitations is required.

Herein, an environment friendly paper-based biobattery is demonstrated that yields a power of 12.5W/m3. Whatman filter papers were used not only as support for electrode fabrication but also as separator of the biobattery. To provide electrical conductivity to the paper-based cathode and anode, commercially available eyeliner containing carbon nanoparticles and Fe3O4 was directly employed as conductive ink without any binder. With an instant start-up, the as-fabricated biocompatible electrodes could hold bacteria in an active form at the anode allowing chemical oxidation of organic fuel producing current. The facile process delineated here can be employed for the tailored electrode fabrication of various flexible energy harnessing devices.

The present work deals with a frugal paper-based microbial fuel cell (PMFC) that generates an average power of 25 μW per device using Shewanella putrefaciens. Bacteria colonized on the paper matrix can be activated by readily available nutrient sources leading to instant power generation. Current study translates this technology to energize a wireless Internet of Things (IoT) sensor. A well-designed stacking of multiple cells is adopted to boost the power output. The power profile characteristics of three 10-unit PMFC configurations namely series (C1), parallel (C2), and combination of both (C3) are investigated. Attempts to directly charge a supercapacitor using serially-connected PMFC stack results in voltage reversal (VR). Hence, to harvest this microbial energy prudently, a customized power management system consisting of integrated Maximum Power Point Tracking (MPPT) feature is deployed. This helps in interfacing the PMFCs to capture charge, boost the harvested voltage and to prevent voltage reversal (VR). Power harvested from PMFCs is stored into a supercapacitor in order to drive the wireless IoT sensor module, which in turn measures temperature and communicates the data to a smart phone. The current endeavours can pave the way for “bacteria powered IoT devices” by unlocking the potential of microbes through PMFCs.

We present a low-cost, disposable microbial fuel cell fabricated on a paper based platform, having a start-up time of 10 s. The platform deploys ordinary pencil strokes for graphite electrode deposition. The device uses a membrane-less design in a one-time injection (OTI) mode or a continuous capillary driven flow mode (CPF), where oxygen from the atmosphere is used up at the cathode for water formation, leading to the generation of bioelectricity. The performance of the fuel cell is evaluated using two bacterial strains, namely, Pseudomonas aeruginosa IIT BT SS1 and Shewanella putrefaciens. This flexible device is shown to retain bacteria for a period of at least one hour, resulting in the generation of almost 0.4 V using P. aeruginosa and a maximum current of 18 μA using S. putrefaciens without the use of any additional catalysts.