Bioelectrochemical systems (BESs) for agro-food waste and wastewater treatment, and sustainable bioenergy-A review.

Producing food by farming and subsequent food manufacturing are central to the world's food supply, accounting for more than half of all production. Production is, however, closely related to the creation of large amounts of organic wastes or byproducts (agro-food waste or wastewater) that negatively impact the environment and the climate. Global climate change mitigation is an urgent need that necessitates sustainable development. For that purpose, proper agro-food waste and wastewater management are essential, not only for waste reduction but also for resource optimization. To achieve sustainability in food production, biotechnology is considered as key factor since its continuous development and broad implementation will potentially benefit ecosystems by turning polluting waste into biodegradable materials; this will become more feasible and common as environmentally friendly industrial processes improve. Bioelectrochemical systems are a revitalized, promising biotechnology integrating microorganisms (or enzymes) with multifaceted applications. The technology can efficiently reduce waste and wastewater while recovering energy and chemicals, taking advantage of their biological elements' specific redox processes. In this review, a consolidated description of agro-food waste and wastewater and its remediation possibilities, using different bioelectrochemical-based systems is presented and discussed together with a critical view of the current and future potential applications.

Microalgae biomass deconstruction using green solvents: Challenges and future opportunities.

Microalgae enablefixation of CO2into carbohydrates, lipids, and proteins through inter and intracellularly biochemical pathways. These cellular components can be extracted and transformed into renewable energy, chemicals, and materials through biochemical and thermochemical transformation processes.However, recalcitrant cell wall andlack of environmentally benign efficient pretreatment processes are key obstacles in the commercialization of microalgal biorefineries.Thus,current article describes the microalgal chemical structure, type, and structural rigidity and summarizes the traditional pretreatment methods to extract cell wall constituents. Green solvents such as ionic liquid (ILs), deep eutectic solvents (DES), and natural deep eutectic solvents (NDESs) have shown interesting solvent characteristics to pretreat biomass with selective biocomponent extraction from microalgae. Further research is needed in task-specific IL/DES design, cation-anion organization, structural activity understanding of ILs-biocomponents, environmental toxicity, biodegradability, and recyclability for deployment of carbon-neutral technologies. Additionally, coupling the microalgal industry with biorefineries may facilitate waste management, sustainability, and gross revenue.

Synthesis of fatty acid-based ammonium ionic liquids and their application for extraction of Co(II) and Ni(II) metals ions from aqueous solution.

Leaching of cobalt and nickel into diverse water streams has become an environmental hazard and is continuously impacting human health through the food chain. Solvent extraction is the most widely accepted for separating these metals, but traditional extractants employed in conjunction with molecular diluents often lack selectivity and caused major environmental hurdles. Therefore, the development of cost-effective, environmentally friendly technologies for recovering these heavy metals has been strongly encouraged in recent years. Herein, two halogens free, low viscous, biocompatible fatty acid-based hydrophobic ionic liquids (ILs), i.e., methytrioctylammonium oleate, methytrioctylammonium linoleate were synthesized, analytically characterized and employed for recovery of cobalt, Co(II) and nickel, Ni(II) from their aqueous solutions. Extraction behaviour of Co(II) and Ni(II) was further evaluated by varying equilibrium time, ILs molar concentration, metal loading, and temperature. Thermodynamic parameters such as enthalpy change and Gibbs free energy change were also studied during extraction process. Slope analysis suggested that the extraction mechanism was an exothermic process that followed ion-transfer from the aqueous phase to the organic phase. Results showed that both fatty acid based-ILs were found to be capable of extracting >99% of Co(II) and Ni(II) from aqueous solutions at 298 K, in 15 min of shaking time using a 1:1 (org: aq.) ratio at low concentrations of 2.5-10 g L-1. Furthermore, for methyltrioctylammonium oleate IL, Co(II) extraction was selectively preferred over Ni(II) extraction when the metal concentration was increased to above to 10 g L-1. The stripping results showed that 2 M H2SO4, and 2 M HCl successfully stripped out >99% of Co(II) and Ni(II) from the organic phase, respectively compared to HNO3.

Bioelectrochemical systems in aid of sustainable biorefineries for the production of value-added products and resource recovery from wastewater: A critical review and future perspectives.

Bioelectrochemical systems (BES) have the potential to be used in a variety of applications such as waste biorefinery, pollutants removal, CO2 capture, and the electrosynthesis of clean and renewable biofuels or byproducts, among others. In contrast, many technical challenges need to be addressed before BES can be scaled up and put into real-world applications. Utilizing BES, this review article presents a state-of-the-art overall view of crucial concepts and the most recent innovative results and achievements acquired from the BES system. Special attention is placed on a hybrid approach for product recovery and wastewater treatment. There is also a comprehensive overview of waste biorefinery designs that are included. In conclusion, the significant obstacles and technical concerns found throughout the BES studies are discussed, and suggestions and future requirements for the virtual usage of the BES concept in actual waste treatment are outlined.

Comparison of alkali and ionic liquid pretreatment methods on the biochemical methane potential of date palm waste biomass.

Date palm waste biomass is a readily accessible agricultural waste biomass that may be used to produce biogas. Because the complex structure of date palm waste biomass prevents the embedded holo-cellulosic sugars from biodegrading, pretreatment is required to increase methane (CH4) yield. The present investigation aimed to comparatively determine the impact of alkali and ionic liquid pretreatment on the biochemical methane potential (BMP) of different types of date palm waste biomass. The findings revealed that ionic liquid pretreated Palm and Fruit bunch showed the highest BMP (321.67 mL CH4/g-TS) and substrate conversion efficiency (68.01%), respectively, over other biomass samples. In alkali pretreatment, the highest BMP and substrate conversion efficiency were detected with Palm (309.76 mL CH4/g-TS) and Spathe (62.09%). The high BMP and substrate conversion efficiency of date palm waste biomass may be harnessed for bioenergy production when this ionic liquid pretreatment technology is used.

Critical challenges and technological breakthroughs in food waste hydrolysis and detoxification for fuels and chemicals production.

Organic waste has increased as the global population and economy have grown exponentially. Food waste (FW) is posing a severe environmental issue because of mismanaged disposal techniques, which frequently result in the squandering of carbohydrate-rich feedstocks. In an advanced valorization strategy, organic material in FW can be used as a viable carbon source for microbial digestion and hence for the generation of value-added compounds. In comparison to traditional feedstocks, a modest pretreatment of the FW stream utilizing chemical, biochemical, or thermochemical techniques can extract bulk of sugars for microbial digestion. Pretreatment produces a large number of toxins and inhibitors that affect bacterial fuel and chemical conversion processes. Thus, the current review scrutinizes the FW structure, pretreatment methods (e.g., physical, chemical, physicochemical, and biological), and various strategies for detoxification before microbial fermentation into renewable chemical production. Technological and commercial challenges and future perspectives for FW integrated biorefineries have also been outlined.

Recent biotechnological developments in reshaping the microalgal genome: A signal for green recovery in biorefinery practices.

The use of renewable energy sources as a substitute for nonrenewable fossil fuels is urgently required. Algae biorefinery platform provides an excellent alternate to overcome future energy problems. However, to let this viable biomass be competent with existing feedstocks, it is necessary to exploit genetic manipulation and improvement in upstream and downstream platforms for optimal bio-product recovery. Furthermore, the techno-economic strategies further maximize metabolites production for biofuel, biohydrogen, and other industrial applications. The experimental methodologies in algal photobioreactor promote high biomass production, enriched in lipid and starch content in limited environmental conditions. This review presents an optimization framework combining genetic manipulation methods to simulate microalgal growth dynamics, understand the complexity of algal biorefinery to scale up, and identify green strategies for techno-economic feasibility of algae for biomass conversion. Overall, the algal biorefinery opens up new possibilities for the valorization of algae biomass and the synthesis of various novel products.

Regulation and augmentation of anaerobic digestion processes via the use of bioelectrochemical systems.

Anaerobic digestion (AD) is a biological process that can be used to treat a wide range of carbon-rich wastes and producerenewable, green energy. To maximize energy recovery from various resources while controlling inhibitory chemicals, notwithstanding AD's efficiency, many limitations must be addressed. As a result, bioelectrochemical systems (BESs) have emerged as a hybrid technology, extensively studied to remediate AD inhibitory chemicals, increase AD operating efficacy, and make the process economically viable via integration approaches. Biogas and residual intermediatory metabolites such as volatile fatty acids are upgraded to value-added chemicals and fuels with the help of the BES as a pre-treatment step, within AD or after the AD process. It may also be used directly to generate power. To overcome the constraints of AD in lab-scale applications, this article summarizes BES technology and operations and endorses ways to scale up BES-AD systems in the future.

Upgrading the value of anaerobic fermentation via renewable chemicals production: A sustainable integration for circular bioeconomy.

The single bioprocess approach has certain limitations in terms of process efficiency, product synthesis, and effective resource utilization. Integrated or combined bioprocessing maximizes resource recovery and creates a novel platform to establish sustainable biorefineries. Anaerobic fermentation (AF) is a well-established process for the transformation of organic waste into biogas; conversely, biogas CO2 separation is a challenging and expensive process. Biological fixation of CO2 for succinic acid (SA) mitigates CO2 separation issues and produces commercially important renewable chemicals. Additionally, utilizing digestate rich in volatile fatty acid (VFA) to produce medium-chain fatty acids (MCFAs) creates a novel integrated platform by utilizing residual organic metabolites. The present review encapsulates the advantages and limitations of AF along with biogas CO2 fixation for SA and digestate rich in VFA utilization for MCFA in a closed-loop approach. Biomethane and biohydrogen processes CO2 utilization for SA production is cohesively deliberated along with the role of biohydrogen as an alternative reducing agent to augment SA yields. Similarly, MCFA production using VFA as a substrate and functional role of electron donors namely ethanol, lactate, and hydrogen are comprehensively discussed. A road map to establish the fermentative biorefinery approach in the framework of AF integrated sustainable bioprocess development is deliberated along with limitations and factors influencing for techno-economic analysis. The discussed integrated approach significantly contributes to promote the circular bioeconomy by establishing carbon-neutral processes in accord with sustainable development goals.

Recent advances in commercial biorefineries for lignocellulosic ethanol production: Current status, challenges and future perspectives.

Cellulosic ethanol production has received global attention to use as transportation fuels with gasoline blending virtue of carbon benefits and decarbonization. However, due to changing feedstock composition, natural resistance, and a lack of cost-effective pretreatment and downstream processing, contemporary cellulosic ethanol biorefineries are facing major sustainability issues. As a result, we've outlined the global status of present cellulosic ethanol facilities, as well as main roadblocks and technical challenges for sustainable and commercial cellulosic ethanol production. Additionally, the article highlights the technical and non-technical barriers, various R&D advancements in biomass pretreatment, enzymatic hydrolysis, fermentation strategies that have been deliberated for low-cost sustainable fuel ethanol. Moreover, selection of a low-cost efficient pretreatment method, process simulation, unit integration, state-of-the-art in one pot saccharification and fermentation, system microbiology/ genetic engineering for robust strain development, and comprehensive techno-economic analysis are all major bottlenecks that must be considered for long-term ethanol production in the transportation sector.

Extraction and characterization of microalgae-derived phenolics for pharmaceutical applications: A systematic review.

Microalgae are regarded as a rich trove of diverse secondary metabolites that exert remarkable biological activities. In particular, microalgae-derived bioactive phenolic compounds (MBPCs) are a boon to biopharmaceutical and nutraceutical industries due to their diverse bioactivities, including antimicrobial, anticancer, antiviral, and immunomodulatory activities. The state-of-the-art green technologies for extraction and purification of MBPCs, along with the modern progress in the identification and characterization of MBPCs, have accelerated the discovery of novel active pharmaceutical compounds. However, several factors regulate the production of these bioactive phenolic compounds in microalgae. Furthermore, some microalgae species produce toxic phenolic compounds that negatively impact the aquatic ecosystem, animal, and human life. Therefore, the focus of this review paper is to bring into light the current innovations in bioprospection, extraction, purification, and characterization of MBPCs. This review is also aimed at a better understanding of the physicochemical factors regulating the production of MBPCs at an industrial scale. Finally, the present review covers the recent advances in toxicological evaluation, diverse applications, and future prospects of MBPCs in biopharmaceutical industries.

Algae biorefinery: A promising approach to promote microalgae industry and waste utilization.

Microalgae have a number of intriguing characteristics that make them a viable raw material aimed at usage in a variety of applications when refined using a bio-refining process. They offer unique capabilities that allow them to be used in biotechnology-related applications. As a result, this review explores how to increase the extent to which microalgae may be integrated with various additional biorefinery uses in order to improve their maintainability. In this study, the use of microalgae as potential animal feed, manure, medicinal, cosmeceutical, ecological, and other biotechnological uses is examined in its entirety. It also includes information on the boundaries, openings, and improvements of microalgae and the possibilities of increasing the range of microalgae through techno-economic analysis. According to the findings of this review, financing supported research and shifting the focus of microalgal investigations from biofuels production to biorefinery co-products can help guarantee that they remain a viable resource. Furthermore, innovation collaboration is unavoidable if one wishes to avoid the high cost of microalgae biomass handling. This review is expected to be useful in identifying the possible role of microalgae in biorefinery applications in the future.

Use of Industrial Wastes as Sustainable Nutrient Sources for Bacterial Cellulose (BC) Production: Mechanism, Advances, and Future Perspectives.

A novel nanomaterial, bacterial cellulose (BC), has become noteworthy recently due to its better physicochemical properties and biodegradability, which are desirable for various applications. Since cost is a significant limitation in the production of cellulose, current efforts are focused on the use of industrial waste as a cost-effective substrate for the synthesis of BC or microbial cellulose. The utilization of industrial wastes and byproduct streams as fermentation media could improve the cost-competitiveness of BC production. This paper examines the feasibility of using typical wastes generated by industry sectors as sources of nutrients (carbon and nitrogen) for the commercial-scale production of BC. Numerous preliminary findings in the literature data have revealed the potential to yield a high concentration of BC from various industrial wastes. These findings indicated the need to optimize culture conditions, aiming for improved large-scale production of BC from waste streams.

Bio-electrocatalytic remediation of hydrocarbons contaminated soil with integrated natural attenuation and chemical oxidant.

The present study aimed to assess the possibility of integrating natural attenuation (NA) and chemical oxidation (O) with the bio-electrocatalytic remediation (BET) process to remediate petroleum hydrocarbons contaminated soil. Six different reactors were operated, wherein in the first reactor was a NA system, and the second condition to the NA was supplemented with a chemical oxidant (NAO). These systems were compared with BET systems which were differentiated based on the position and distance between the electrodes. The study was performed by considering NA as a common condition in all the six different reactors viz., NA, NAO, NA + BET with 0.5 cm space amid electrodes (BETH-0.5), NAO + BET with 0.5 cm space amid electrodes (BETOH-0.5), NAO + BET with 1.0 cm space amid electrodes (BETOH-1.0), and NAO + BET with vertical electrodes at 1.0 cm distance (BETOV-1.0). The highest total petroleum hydrocarbons (TPH) degradation efficiency was observed with BETOH-0.5 (67 ± 0.8%) followed by BETOH-1.0 (62 ± 0.6%), BETH-0.5 (60%), BETOV-1.0 (56 ± 0.5%), NAO (46.6%), and NA (27.7%). In NA, the indigenous microorganisms remediate the organic contaminants. In the NAO system, KMnO4 actively breakdown the carbon-carbon double bond functional group. Further, in BETOH-0.5, an anodophilic bacteria enriched around the electrode reported enhanced treatment efficiency along with a maximum of 260 mV (1.65 mA). BET systems integrated with chemical oxidation processes were much more effective in the TPH removal process than an individual process. The BET method adopted here thus provides a good opportunity for bio-electrocatalytic remediation of TPH and resource recovery in the form of bioelectricity.

Electro-fermentation for biofuels and biochemicals production: Current status and future directions.

Electro-fermentation is an emerging bioporcess that could regulate the metabolism of electrochemically active microorganisms. The provision of electrodes for the fermentation process that functions as an electron acceptor and supports the formation and transportation of electrons and protons, consequently producing bioelectricity and value-added chemicals. The traditional method of fermentation has several limitations in usability and economic feasibility. Subsequently, a series of metabolic processes occurring in conventional fermentation processes are most often redox misaligned. In this regard, electro-fermentation emerged as a hybrid technology which can regulate a series of metabolic processes occurring in a bioreactor by regulating the redox instabilities and boosting the overall metabolic process towards high biomass yield and enhanced product formation. The present article deals with microorganisms-electrode interactions, various types of electro-fermentation systems, comparative evaluation of pure and mixed culture electro-fermentation application, and value-added fuels and chemical synthesis.

State-of-the-art technologies for continuous high-rate biohydrogen production.

Dark fermentation is a technically feasible technology for achieving carbon dioxide-free hydrogen production. This review presents the current findings on continuous hydrogen production using dark fermentation. Several operational strategies and reactor configurations have been suggested. The formation of attached mixed-culture microorganisms is a typical prerequisite for achieving high production rate, hydrogen yield, and resilience. To date, fixed-bed reactors and dynamic membrane bioreactors yielded higher biohydrogen performance than other configurations. The symbiosis between H2-producing bacteria and biofilm-forming bacteria was essential to avoid washout and maintain the high loading rates and hydrogenic metabolic flux. Recent research has initiated a more in-depth comparison of microbial community changes during dark fermentation, primarily with computational science techniques based on 16S rRNA gene sequencing investigations. Future techno-economic analysis of dark fermentative biohydrogen production and perspectives on unraveling mitigation mechanisms induced by attached microorganisms in dark fermentation processes are further discussed.

Waste based hydrogen production for circular bioeconomy: Current status and future directions.

The present fossil fuel-based energy sector has led to significant industrial growth. On the other hand, the dependence on fossil fuels leads to adverse impact on the environment through releases of greenhouse gases. In this scenario, one possible substitute is biohydrogen, an eco-friendly energy carrier as high-energy produces. The substrates rich in organic compounds like organic waste/wastewater are very useful for improved hydrogen generation through the dark fermentation. Thus, this review article, initially, the status of biohydrogen production from organic waste and various strategies to enhance the process efficiency are concisely discussed. Then, the practical confines of biohydrogen processes are thoroughly discussed. Also, alternate routes such as multiple process integration approach by adopting biorefinery concept to increase overall process efficacy are considered to address industrial-level applications. To conclude, future perspectives besides with possible ways of transforming dark fermentation effluent to biofuels and biochemicals, which leads to circular bioeconomy, are discussed.

Distinguishing between Bread Wheat and Spelt Grains Using Molecular Markers and Spectroscopy.

The increasing demand for spelt products requires the baking industry to develop accurate and efficient tools to differentiate between spelt and bread wheat grains. We subjected a 272-sample spelt-bread wheat set to several potential diagnostic methods. DNA markers for γ-gliadin-D ( GAG56D), γ-gliadin-B ( GAG56B), and the Q-gene were used, alongside phenotypic assessment of ease-of-threshing and near-infrared spectroscopy (NIRS). The GAG56B and GAG56D markers demonstrated low diagnostic power in comparison to the Q-gene genotyping, which showed full accordance with the threshing phenotype, providing a highly accurate distinction between bread wheat and spelt kernels. A highly reliable Q classification was based on a three-waveband NIR model [Kappa (0.97), R-square (0.93)], which suggested that this gene influences grain characteristics. Our data ruled out a protein concentration bias of the NIRS-based diagnosis. These findings highlight the Q gene and NIRS as important, valuable, but simple tools for distinguishing between bread wheat and spelt.

Design of a non-invasive pulse rate controlled deep vein thrombosis prophylaxis lower limb device.

Patients with lower limb dysfunctions have a risk of developing deep vein thrombosis (DVT) symptoms if they are in a sitting posture for a long duration. In addition, unconscious patients undergoing a long hour surgery are also prone to DVT problems which further complicates the health of the patient under treatment. A prototype design in the form of an assistive and portable device to overcome deep vein thrombosis (DVT) is developed for surgical and non-surgical applications. The portable device facilitates the movement of the lower limb around the ankle to promote blood flow and overcome DVT problem. The device is designed using a pair of actuators that translates the linear motion to axial flexion and extension movement of the ankle. The ankle movement is synchronized with the patient's heartbeats to promote blood flow and complete the venous movement. In addition, an electrically driven intermittent pneumatic compression layer is wrapped around the calf muscle to further enhance the blood flow in the lower limb. The integrated device is lightweight and portable which can be issued by the hospital centers to the patients for domestic utilization.