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In the present work, an effluent-free novel method including cyclic vacuum steam pulsed blanching (VSPB) pretreatment and non-water infrared refractance window drying (non-water IR-RWD) was employed to explore its effect on enzyme inactivation, drying behavior, quality and functional properties of dried Malabar spinach. The highest inactivation of peroxidase (90.23 %) and polyphenol oxidase (94.58 %) was observed in the 4th cycle of the VSPB pretreatment. With the increase in VSPB cycles from 1 to 5, the drying time was significantly reduced by 27.27 % to 54.54 % compared to the untreated sample. The color change values (ΔE) of VSPB pretreated non-water IR-RWD samples varied from 7.37 to 8.03. The findings in the current work indicated that vacuum-steam pulsed blanching combined with a non-water IR-RWD process is a promising technique for Malabar spinach powder production. • Vacuum steam pulsed blanching (VSPB) reduced drying time by 54.54 %. • The 4th cycle VSPB showed an effective reduction in enzyme activity. • VSPB enhanced total chlorophyll and total phenolic content of Malabar spinach. • VSPB combined with drying gives high-quality Malabar spinach powder. [ABSTRACT FROM AUTHOR]

Hydroponics, as an adjunct to traditional agriculture, enhances crop production by providing optimal plant growth conditions but faces environmental challenges due to incomplete nutrient utilization. Cultivating microalgae in hydroponic effluent offers an efficient solution to reclaim unused nutrients. While mixotrophic microalgal cultivation is familiar, its application in treating hydroponic effluent remains underexplored, with limited insights into how varying different organic carbon levels of supplements in the hydroponic effluent impact microalgal growth, biomass composition, and nutrient removal efficiency. To bridge this gap, the present study cultivated a microalgal consortium with two different organic carbon sources, glucose (0 to 0.75% w/v) and glycerol (0 to 0.75% v/v), at varying concentrations to investigate the impact of altered carbon:nitrogen ratio on biomass productivity, nutrient utilization, and biomass composition compared to autotrophic condition. Results reveal that mixotrophic cultivation outperformed autotrophic systems in nutrient removal, biomass productivity and microalgal lipid content, with glucose and glycerol as effective organic carbon substrates. Compared to autotrophic cultivation, mixotrophic cultivation with 0.5% w/v glucose significantly boosted biomass productivity by ~55%, nutrient removal by 20-60% and lipid content by 44%, while culture supplemented with 0.25% v/v glycerol achieved a 59% higher biomass productivity, along with a 26-72% increase in nutrient removal and ~70% higher lipid content. These findings indicate that mixotrophic cultivation, particularly with low-cost carbon sources like glycerol, offers a cost-effective approach for nutrient recovery from hydroponic effluent, along with producing lipid-rich microalgal biomass, offering both economic and environmental benefits. Exploring cheaper organic carbon sources could further improve process feasibility. [ABSTRACT FROM AUTHOR]

The investigation of microwave pyrolysis behavior and interactive effects of process parameters through machine learning is necessary to systematically determine the combined effects on the yield and characteristics of biochar. This study involves the prediction of microwave biochar yield and its property using various machine learning approaches. Based on the input data of feedstock characteristics (elemental and proximate composition) and operating conditions of microwave pyrolysis (microwave power, time, weight, absorber), the output targets like biochar yield and higher heating value (HHV) have been predicted. The results suggested that eXtreme Gradient Boosting (XGB) model with optimal hyper-parameters could predict the yield and HHV of microwave-derived biochar with higher correlation coefficient (R2) of 0.91. The impact of each factor on output target and their interactions during microwave pyrolysis has been observed from SHAP (SHapley Additive exPlanations) dependence plots. The study outcome revealed that microwave power is the most significant feature influencing the yield of biochar and its property (HHV). The present work gives an insight through computational approach in improving microwave pyrolysis of biomass for enhanced biochar yield and its properties. [ABSTRACT FROM AUTHOR]

In response to escalating global wastewater issues, particularly from dye contaminants, many studies have begun using hydrochar to adsorb dye from wastewater. However, the relationship between the preparation conditions of hydrochar, the properties of hydrochar, experimental conditions, types of dyes, and equilibrium adsorption capacity (Q) has not yet been fully explored. This study conducted a comprehensive assessment using twelve distinct ML models. The Gradient Boosting Regressor (GBR) model exhibited superior performance with R² (0.9629) and RMSE (0.1166) in the test dataset, marking it as the most effective among the evaluated models. Moreover, this study also proved the feasibility of the GBR model through stability testing and residual analysis. A feature importance analysis prioritized the variables as follows: experimental conditions (41.5 %), properties of hydrochar (26.0 %), preparation conditions (18.1 %), and type of dye (14.4 %). Meanwhile, experimental conditions (C 0 > 30 mmol/g, pH > 8, and higher solvent temperatures) and hydrochar properties (the BET surface area > 2000 m²/g, an (O+N)/C molar ratio < 0.6, and an H/C molar ratio of approximately 0.06) show higher Q for dyes. Experimental validation of the GBR model confirmed its practical utility with a suitable predictive accuracy (R² = 0.8704). Moreover, the study developed a Python-based GUI that has integrated the best GBR models to facilitate researchers' ongoing application and improvement of this predictive model. This study not only underscores the efficacy of ML in enhancing the understanding of dye adsorption by hydrochar but also sets a precedent for future research on sustainable contaminants removal through bio-based adsorbents. [Display omitted] • Twelve ML models were tested, with the Gradient Boosting Regressor standing out for its exceptional performance. • The experimental verification showed the promising potential of the developed model. • SHAP and PDP were introduced for model interpretation. • An easy-to-use graphical user interface was developed for hydrochar absorb dyes. [ABSTRACT FROM AUTHOR]

The aim of the study was to utilize kombucha-derived bacterial cellulosic sheet [KBC], formed as a by-product of fermented, sugared black tea (in the presence of a symbiotic culture of bacteria and yeast), for potential wound dressing applications. KBC was functionalized using aqueous and ethanolic extracts of different phytochemical agents using two ex-situ methods- casting and impregnation. It was observed that casted KBC functionalized with ethanolic extract of Turmeric (1.2% w/w) yielded a maximum zone of inhibition (24.37 ± 0.42 mm) against Pseudomonas aeruginosa. The hemocompatibility test confirmed the composite's biocompatible nature as the percentage hemocompatibility was found to be less than 5%. The MTT assay established its viability and anti-cancerous properties with Turmeric extract loaded KBC showing higher efficiency compared to Tulsi extract. FTIR analysis and SEM imaging confirmed the functionalization of cellulose sheets and the change in morphology. The contact angle analysis showed improved hydrophilic properties of the sheets for absorbing wound exudates, and the water absorption study revealed maximum absorptivity of up to 321.20 ± 6.23%. Thus, it can be concluded from the study that tea processing waste can be reused to produce a value-added product that can act as an efficient, cost-effective biomaterial for wound dressing applications. [ABSTRACT FROM AUTHOR]

Phycocyanin, a blue-coloured pigment, predominantly found and derived from Spirulina sp., has gained researchers' interest due to its vibrant hues and other attractive properties like antioxidant and anti-microbial. However, the lack of reliable and sustainable phycocyanin extraction strategies without compromising the quality has hindered the scaling up of its production processes for commercial purposes. Here in this study, phycocyanin was extracted from wet and dry biomass Spirulina sp., using three different physical cell disruption methods (ultrasonication, homogenization, and freeze–thaw cycles) combined with two different buffers (phosphate buffer and acetate buffer) and water (as control). The result showed that the freeze–thaw method combined with acetate buffer produced the highest yield (25.013 ± 2.572 mg/100 mg) with a purity ratio of 0.806 ± 0.079. Furthermore, when subjected to 30% w/v salt stress, 1.9 times higher phycocyanin yield with a purity ratio of 1.402 ± 0.609 was achieved using the previously optimized extraction method. [ABSTRACT FROM AUTHOR]

The alarming decline in phosphate raw materials and increase in eutrophication has escalated interest in struvite research. This manuscript presents scientometric analysis on struvite for fertilizing applications to comprehend the evolution and transformation of the field, investigate the existing challenges, research gaps, and developments to gain insights on the emerging trends for further studies. A total of 1550 scientific documents, between the years 1999–2020, were collected from Scopus® and PubMed® using an appropriate trail of keywords and analyzed using CiteSpace 5.7. R2. Ten attributes such as annual publication output and types, co-authorship network, co-occurring author keywords, the network of authors' countries and institutions, author co-citation network, document co-citation network, journal co-citation network, and co-occurring subject categories were investigated. Based on the distinct network patterns generated by the software, progress of the field, paradigm shifts, knowledge gaps, and scientific frontiers were identified and mapped. The literature on struvite research was found to have bloomed in the early 2000s and accelerated significantly until now, with maximum contribution from China and United States. Journal of cleaner production ranks 5th with 3.35% share of the total contribution according to journal co-citation analysis. Cluster analysis of co-occurring author keywords revealed the research progression through the expanse, knowledge gaps, disciplinary and inter-disciplinary advancements, and future exploration trends. The research has evolved from evaluating the process influencing parameters and developing suitable reactor designs to installation of pilot-scale plants for commercialization. However, lack of experiments on real-time wastewater, plant growth studies and the underlying nutrient uptake mechanisms persist as major research gaps. Focussing on these aspects along with integrated advanced technologies such as microbial fuel cells, microbial electrolysis cells, electrochemical precipitation of struvite and wider application of struvite can pave way for enormous progress of this field. [Display omitted] • Scientometric analysis of struvite research over the last 20 years were performed. • Ten scientometric attributes on struvite research arena were explored. • Research gaps, trends and future scope in struvite research were highlighted. • The commercial scenario of struvite for fertilizer applications were emphasized. [ABSTRACT FROM AUTHOR]

[Display omitted] • Algal drying characteristics of convective hot air and microwave oven were discussed. • Microwave drying is faster with relatively lower specific energy requirements. • Convective and microwave drying followed thin layer drying models. • 14.4% higher lipid content was obtained in microwave dried algal biomass. • Uniform volumetric heating in microwave drying preserves biochemical content. Conventional microalgal drying consumes huge time and contributes to 60–80% of downstream process costs. With the aim to develop an effective and rapid drying process, the present study evaluated the performance of microwave based drying (MWD) with a power range of 360–900 W and compared with the conventional oven drying (OD) at 40–100 °C. MWD was found to be efficient due to uniform and volumetric heating because of dipolar interaction, with an effective diffusivity of 0.47 × 10−9−1.63 × 10−9 m2 s−1, comparatively higher than OD. Activation and specific energy of 32.43 W g−1 and 42.9–56.07 kWh kg−1 was projected respectively, and a falling rate period with best fit for Newton and Henderson-Pabis model was observed for MWD. Uniform heating from internal sub-surface avoided cell distress, resulting in 14.4% higher lipid yield and significant preservation of biochemical components that can be processed into bioenergy and valuable products in microalgal biorefinery. [ABSTRACT FROM AUTHOR]

Developing sustainable materials for recovering and recycling nutrients from wastewater is critically needed for nutrients such as phosphorus that have a diminishing supply. Struvite crystallization is emerging as a promising strategy for phosphorus recovery which can be enhanced with seeding through microalgal biochar. The main bottleneck of using microalgae is its high harvesting cost. In this study, an integrated electrocoagulation-flotation (ECF) process is used to recover and at the same time modify the algal surface with magnesium anode and inert carbon cathode. Harvesting efficiency of 98% was achieved with 40.78 mA cm−2, 0.5 cm inter-electrode distance and energy consumption of 4.03 kWh kg−1 in 15 min. The harvested microalgae were pyrolyzed to obtain a yield of 52.90% Mg-laden microalgal biochar. Simultaneously, surface impregnation of 28% magnesium was attained as confirmed by Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Phosphorus recovery and struvite yield of 93.70% and 2.66 g L−1, respectively, were obtained from dosing 1.50 g L−1 Mg-laden microalgal biochar. Comparison of physicochemical characteristics of residual supernatant after microalgal harvesting and struvite recovery showed that the combined use of both the residuals can serve as a sustainable growth medium for microalgae. The overall operating cost of the integrated process was found to be 2.48 USD kg−1 with a total energy consumption of 10.76 kWh kg−1, which was found to be lower than conventional harvesting unit processes such as centrifugation and filtration. This novel approach can help attaining a circular bioeconomy by encompassing nutrient recovery and waste management in an integrated process. [ABSTRACT FROM AUTHOR]

Kombucha bacterial cellulose (KBC), obtained as a by-product of tea fermentation, has potential applications in diverse fields. The high water content and presence of post-fermentation residues necessitate the implementation of suitable drying conditions that can significantly affect the final characteristics of this versatile biopolymer. Thus, to study the effect of different drying methods on its properties, KBC was subjected to microwave drying (180–900 W), hot air oven drying (30–70 °C), and shade drying (25 °C). Additionally, the acquired data were fitted into ten different models to study the drying kinetics of KBC. The dried sheets were then analyzed to study the changes in water absorption and holding capacity, rehydration, surface color, and other physicomechanical properties (UTM , XRD , and contact angle analysis). Hence, optimization of the drying conditions will help reduce the time and cost without compromising any of the intrinsic properties that allow it to be processed into various value-added products. [Display omitted] • Effect of different drying conditions on kombucha bacterial cellulose was assessed. • Page (microwave) and parabolic model (hot air-oven) provided optimal representation. • Different drying conditions showed significant effects on its intrinsic properties. • Effective diffusivity ranged from 6.23*10−11m2s−1 to 48.27*10−11 m2s−1. • Microwave drying proved to be the most efficient drying method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Process, mechanisms and product portfolio for algal HTC/HTL/HTG were reviewed. • Research on HTL of algal biomass has been more focused compared to HTC/HTG. • Enviro-economic feasibility constraints to be addressed for scale-up. • Process optimization, integration and supply chain management must be emphasized. • Holistic thermochemical engineering perspectives promote food-water-energy nexus. Hydrothermal processing of microalgae is regarded as a promising technology to generate multitude of energy based and value-added products. The niche of hydrothermal technologies is still under infancy in terms of the technical discrepancies related to research and development. Thus, the present review critically surveyed the recent advancements linked to the influencing factors governing the algal hydrothermal processing in terms of the product yield and quality. The sustainability of hydrothermal technologies as a standalone method and in broader aspects of circular bio-based economy for energy and value-added platform chemicals are comprehensively discussed. Process optimization and strategic integration of technologies has been suggested to improve efficiency, with reduced energy usage and environmental impacts for addressing the energy-food-water supply chains. Within the wider economic transition and sustainability debate, the knowledge gaps identified and the research hotspots fostering future perspective solutions proposed herewith would facilitate its real-time implementation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Kombucha cellulose biofilm (KCB) fermentation depends on operational conditions. • Techno-economic analysis (TEA) of production and processing of KCB. • Facility dependent and labor charges are key economic drivers. • KCB production is economically feasible with reasonable rate of returns. • Payback time of 4.23 years was predicted through TEA. Bacterial cellulose produced during Kombucha fermentation has recently received lots of attention owing to its desirable mechanical and physicochemical properties and is exploited for different food, textiles and environmental applications. However, lack of information on process feasibility often hinders large-scale manufacturing of Kombucha-based cellulose. Therefore, the current study assesses techno-economic feasibility of a 60-ton annual capacity Kombucha-based cellulose production facility using SuperPro designer. Economic feasibility analysis showed an estimation of 13.72 million US$ as total investment and 3.8 million US$ as operating costs with 89% expenses associated with facility dependent and labour costs. The process feasibility is revealed with a payback time of 4.23 years, 23.64% return on investment and 16.48% internal rate of return. Sensitivity analysis presented that increased volume of fermentation units and automating the process can significantly reduce input costs. Such research is necessary to aid policymakers in facilitating the commercialization of Kombucha-based cellulose at field scale. [ABSTRACT FROM AUTHOR]

Highlights: Enzyme-mimicking activities of different nanomaterials (nanozymes) and the recent progress in the construction of nanozyme-based biosensors with various examples are discussed in this review. Physicochemical properties of nanomaterials (size, composition, pH, temperature, surface chemistry) play crucial role in the nanozyme activities. The emerging nanozyme-based biosensors promise great potential for point-of-care diagnostic applications following the ASSURED criteria defined by WHO.Nanomaterial-based artificial enzymes (or nanozymes) have attracted great attention in the past few years owing to their capability not only to mimic functionality but also to overcome the inherent drawbacks of the natural enzymes. Numerous advantages of nanozymes such as diverse enzyme-mimicking activities, low cost, high stability, robustness, unique surface chemistry, and ease of surface tunability and biocompatibility have allowed their integration in a wide range of biosensing applications. Several metal, metal oxide, metal–organic framework-based nanozymes have been exploited for the development of biosensing systems, which present the potential for point-of-care analysis. To highlight recent progress in the field, in this review, more than 260 research articles are discussed systematically with suitable recent examples, elucidating the role of nanozymes to reinforce, miniaturize, and improve the performance of point-of-care diagnostics addressing the ASSURED (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and deliverable to the end user) criteria formulated by World Health Organization. The review reveals that many biosensing strategies such as electrochemical, colorimetric, fluorescent, and immunological sensors required to achieve the ASSURED standards can be implemented by using enzyme-mimicking activities of nanomaterials as signal producing components. However, basic system functionality is still lacking. Since the enzyme-mimicking properties of the nanomaterials are dictated by their size, shape, composition, surface charge, surface chemistry as well as external parameters such as pH or temperature, these factors play a crucial role in the design and function of nanozyme-based point-of-care diagnostics. Therefore, it requires a deliberate exertion to integrate various parameters for truly ASSURED solutions to be realized. This review also discusses possible limitations and research gaps to provide readers a brief scenario of the emerging role of nanozymes in state-of-the-art POC diagnosis system development for futuristic biosensing applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biopolymers act as a sustainable and green alternative in the food industry. • Active biopolymers help in the preservation and extends the shelf life of food. • Smart packaging conveys the real-time data of the food to the consumers. • Consumer awareness fuels the development of active and smart biopolymers. The improper disposal of petroleum-based plastics has been associated with detrimental environmental consequences, such as the proliferation of microplastic pollution and increased emissions of greenhouse gases (GHGs). Consequently, biopolymers have emerged as a highly regarded alternative due to their environmental-friendly attributes and versatile range of applications. In response to consumer demands for safer food options, sustainable packaging, and escalating environmental concerns, the food sector is increasingly adopting biopolymers. Further, in the recent decade, the usage of active or functional biopolymers has evolved into smart biopolymers that can transmit real-time data to consumers. This review covers key topics such as antimicrobial and biodegradable packaging, edible coatings and films, incorporation of scavengers and bioactive substances that prolong the shelf life and guard against moisture and microbial contamination. The paper also discusses the development of edible cutlery as a sustainable substitute for plastic, the encapsulation of bioactive substances within biopolymers, 3-D food printing for regulated nutrition delivery and thickening and gelling agents that improve food texture and stability. It also discusses the integration of smart polymer functions, demonstrating their importance in guaranteeing food safety and quality, such as biosensing, pH and gas detection, antibacterial characteristics, and time–temperature monitoring. By shedding light on market trends, future scope, and potentialities, this review aims to elucidate the prospects of utilizing biopolymers to address sustainability and quality concerns within the food industry effectively. [ABSTRACT FROM AUTHOR]

Struvite precipitation from source-separated urine is crucial for waste utilization and sustainability. However, after precipitation, the high moisture content of struvite necessitates an additional drying process that can be costly and inefficient. In the present study, the performance of different drying methods—open sun drying, air drying, conventional drying (20–100 °C), and microwave drying (180–720 W) on the quality of struvite obtained from source-separated urine through electrocoagulation using Mg–Mg electrodes were evaluated. It was found that higher temperatures and power in the convective oven and microwave resulted in higher diffusivity (10−9-10−7 m2s−1), leading to reduced drying times. Different models were employed to comprehend the drying mechanism, and the one with the highest correlation coefficient (R 2 = 0.99) and the lowest statistical values was selected. The key findings indicated that higher power and temperature levels were more cost-effective. However, characterization of the dried struvite using X-ray diffraction and Fourier-transformed infrared spectroscopy, disintegration of struvite crystals at temperatures above 60 °C in the conventional oven and 180 W in the microwave oven was observed. Based on the results, we conclude that sun drying is a cost-effective and environmentally friendly alternative for drying struvite without compromising its quality. • Struvite was precipitated through electrocoagulation method from source separated urine. • Different drying methods on struvite quality and its energy requirement were evaluated. • Foremost study reporting the mathematical modelling of drying kinetics of struvite. • Higher temperatures and microwave power showed higher effective diffusivity, resulting in reduced drying time. • XRD and FTIR revealed the impact of temperature on the disintegration of struvite crystals. [ABSTRACT FROM AUTHOR]

[Display omitted] • The potential of algal biomasses to produce biohydrogen is emphasized. • The current technologies and bottlenecks to produce biohydrogen are highlighted. • Different strategies to improve biohydrogen production from algae are discussed. • The advances, research gaps and future scopes of algal biohydrogen are reviewed. Drastic climatic changes and health hazards, in the recent years, due to combustion of fossil fuels has elicited the need to find sustainable and economical fuel alternatives. Hydrogen gas is a versatile energy carrier that can be used for transportation, electricity generation, and industrial processes. It does not produce greenhouse gases or other pollutants when used, making it a promising alternative to fossil fuels. Among the feedstocks used for hydrogen production, algae are found to be a potential source due to their high growth rate, ability to grow in diverse environments, and ability to produce hydrogen via the process of photosynthesis. However, current hydrogen production rates using algae are low, and strategies to improve these rates are needed. This review is aimed to investigate and evaluate different strategies to enhance biohydrogen production using algae. In addition, the prospects of using macro and microalgae as feedstocks have been elucidated. This review also provides brief insights on the current technologies available for algal biohydrogen production and their bottlenecks. The recent advancements, research gaps and future scopes of this research have been highlighted. Overall, the discussion of the various strategies can provide valuable information for the development of cost-effective and sustainable hydrogen production methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biohydrogen production potential of algal biomasses was highlighted. • Factors influencing biohydrogen yield were discussed. • Economics and challenges of biohydrogen production were outlined. • Emerging trends and future scopes of the biohydrogen process were highlighted. The biohydrogen production from algal biomass could ensure hydrogen's sustainability as a fuel option at the industrial level. However, some bottlenecks still need to be overcome to achieve the process's economic feasibility. This review article highlights the potential of algal biomasses for producing hydrogen with a detailed explanation of various mechanisms and enzymes involved in the production processes. Further, it discusses the impact of various experimental parameters on biohydrogen production. This article also analyses the significant challenges confronted during the overall biohydrogen production process and comprehends the recent strategies adopted to enhance hydrogen productivity. Furthermore, it gives a perception of the economic sustenance of the process. Moreover, this review elucidates the future scope of this technology and delineates the approaches to ensure the viability of hydrogen production. [ABSTRACT FROM AUTHOR]