Advanced Photocatalysis as a Viable and Sustainable Wastewater Treatment Process: A Comprehensive Review.

In our era, water pollution not only poses a serious threat to human, animal, and biotic life but also causes serious damage to infrastructure and the ecosystem. A set of physical, chemical, and biological technologies have been exploited to decontaminate and/or disinfect water pollutants, toxins, microbes, and contaminants, but none of these could be ranked as sustainable and scalable wastewater technology. The photocatalytic process can harmonize the sunlight to degrade certain toxins, chemicals, microbes, and antibiotics, present in water. For example, transition metal oxides (ZnO, SnO2, TiO2, etc.), when integrated into an organic framework of graphene or nitrides, can bring about more than 90% removal of dyes, microbial load, pesticides, and antibiotics. Similarly, a modified network of graphitic carbon nitride can completely decontaminate petrochemicals. The present review will primarily highlight the mechanistic aspects for the removal and/or degradation of highly concerned contaminants, factors affecting photocatalysis, engineering designs of photoreactors, and pros and cons of various wastewater treatment technologies already in practice. The photocatalytic reactor can be a more viable and sustainable wastewater treatment opportunity. We hope the researcher will find a handful of information regarding the advanced oxidation process accomplished via photocatalysis and the benefits associated with the photocatalytic-type degradation of water pollutants and contaminants.

Biotransformation of Raw Mango Seed Waste into Bacterial Hydrolytic Enzymes Enhancement Via Solid State Fermentation Strategy.

Solid waste generation is a huge contributor to environmental pollution issues, and food wastes are prominent in this category due to their large generation on a day-to-day basis. Thus, the settlement of daily food waste is one of the major constraints and needs innovative manufacturing sheme to valorize solid waste in sustainable manner. Moreover, these food wastes are rich in organic content, which has promising scope for their value-added products. In the present study, raw mango seed waste has been biotransformed to produce bacterial hydrolytic enzymes as feedstock. On investigating the impact of substrate, the highest bacterial cellulase production was recorded to be 18 IU/gds FP (filter paper) in 24 h of microbial incubation at 5 g of substrate in solid-state fermentation (SSF). Furthermore, at 40 °C and pH 6.0, 23 IU/gds FP enzyme could be produced in 24 h of SSF. Beside this, on comparing the influence of inorganic and organic nitrogen sources, urea has been found to provide better cellulase production, which yielded 28 IU/gds FP in 24 h of incubation, along with 77 IU/gds BG (ß-glucosidase) and 89 IU/gds EG (endoglucanase). On the other hand, Tween-40 and Tween-80, two different surfactants, were employed at a 1.0% concentration for 24 h of incubation. It was noticed that Tween-80 showed complete enzyme activity at 24 h, which was found to be relatively superior to that of Tween-40. This study may have potential utility in enzyme production using mango seed as a food waste for various industrial applications.

Prospects of earthworm coelomic fluid as a potential therapeutic agent to treat cancer.

Cancer is a major public health concern because it is one of the main causes of morbidity and mortality worldwide. As a result, numerous studies have reported the development of new therapeutic compounds with the aim of selectively treating cancer while having little negative influence on healthy cells. In this context, earthworm coelomic fluid has been acknowledged as a rich source of several bioactive substances that may exhibit promising anticancer activity. Therefore, the objective of the present review is to evaluate the findings of the reported studies exploring the antitumor effects of coelomic fluid in the context of its possible utilization as a natural therapeutic agent to cure different types of cancer. The possible mechanisms underlying the coelomic fluid's anticancerous potential as well as the possibility for future development of cutting-edge therapeutic agents utilizing coelomic fluid-derived natural bioactive compounds to treat cancer disorders have been discussed along with future challenges. In addition, the feasibility of encapsulation of bioactive compounds derived from coelomic fluid with nanomaterials that could be further explored to attain more effective anticancer competence is discussed.

Production of fermentable glucose from bioconversion of cellulose using efficient microbial cellulases produced from water hyacinth waste.

The economic production of cellulase enzymes for various industrial applications is one of the major research areas. A number of broad industrial applications, for example, in cellulosic biomass hydrolysis for simple sugars such as glucose and subsequent biofuel production, make these enzyme systems the third most demanding enzymes. Nevertheless, due to their production on commercial substrates, cellulases fall into the category of costly enzymes. Therefore, the goal of the present work is to evaluate the enhancement of cellulase production and its utilization in the enzymatic hydrolysis of biomass using low-cost cellulosic substrate, which is abundant and widely available. In this context, waste biomasses of water hyacinth (WH), including leaves and stems, have been used as feedstock to produce cellulases via solid-state fermentation (SSF) in the current study, which improves its production as well as activity. Furthermore, the impact of process parameters like temperature and pH has been investigated for improved cellulase production. At optimum concentration using 10 g of feedstock, 22 IU/gds of FP, 92 IU/gds of BGL, and 111 IU/gds of EG have been noticed in day 5 of SSF. Herein, 40 °C has been identified as the optimum temperature for cellulase production, whereas 50-55 °C has been recorded as the optimum reaction temperature for cellulase enzyme activity. Additionally, pH 5.5 has been identified as the optimum pH for cellulase enzyme production, whereas this enzyme was thermally stable (55 °C) at pH 5.0 up to 3.5 h. Further, the cellulosic biomass hydrolysis of WH leaves via an optimized crude enzyme has been performed, and this could release 24.34 g/L of glucose in 24 h of the reaction. The current findings may have potential for developing cellulases for mass-scale production using WH-based waste bioresources for numerous biorefinery applications.

Enhancement in Bacterial Cellulolytic Enzyme Production Using Acid-Pretreated Banana Peel Waste: A Comparative Evaluation.

Banana peel waste is one of the major contributors in the issue raised from solid waste, however, it can be valorized effectively due to high content of cellulose and hemicellulose. Significant conversion of banana waste includes cellulolytic enzymes and bioenergy production. In the present study, bacterial cellulase was produced using raw banana peel and ripe banana peel under SSF. Additionally, impact of acid pretreatment was investigated as one of strategy to improve cellulolytic enzyme production. A comparative evaluation of raw and ripe banana peels showed that ripe banana peels showed better enzyme production after pretreatment with 0.5% dilute HCl acid. In the series of enhancement of the enzyme production, temperature and pH of the SSF medium were also investigated, and found temperature 35 °C and pH 6.0 were optimum to produce maximum 3.5-U/ml FPA, 39-U/ml BGL, and 54-U/ml EG in 18-h SSF incubation. The study presented eco-friendly waste management to produce industrial enzyme for its promising application in waste valorization and biorefinery area.

Production Enhancement of Bacterial Cellulase Cocktail Using Potato Peels Waste Feedstock and Combination of Water Hyacinth Root and Pea Pod Extract as Natural Nutrient Media: Application in Bioconversion of Potato Peels.

Solid wastes are the major contributors in global environmental pollution and their management is the need of urgency towards development of sustainable world. In the present work, solid waste of potato peels has been used as feedstock for fermentation of bacterial cellulase production and substrate for enzymatic hydrolysis via this enzymes cocktail. Additionally, liquid extracts of pea pod and root of water hyacinth wastes have been used to complete nutritional requirements and moisture balance in SSF process during the course of enzyme production. At optimum feedstock concentration of 6.0 g PPW and 10:40 extract-based moisture ratio of WHR and Ppw, Bacillus sp. produced 15 U/gds FP in 18 h, whereas maximum 36 U/gds BGL and 42 U/gds EG have been recorded in 24 h of SSF. Temperature 35 °C and pH 5.5 were optimum for enzyme production while the produced enzyme was thermally stable upto 30 h at 35 °C with 100% pH stability upto 14 h and 77% relative activity at 34 h. The optimized bacterial enzymes have been used for bioconversion of PPW biomass and 26 g/L glucose has been recorded at a hydrolytic temperature of 50 °C and pH 5.0. The study may have feasible promising scope in cellulosic biorefineries and waste management.

Facile pretreatment strategies to biotransform Kans grass into nanocatalyst, cellulolytic enzymes, and fermentable sugars towards sustainable biorefinery applications.

The present investigation is targeted towards the facile fabrication of a carbon-based nanocatalyst (CNCs) using Kans grass biomass (KGB) and its sustainable application in microbial cellulase enhancement for the alleviation of enzymatic hydrolysis for sugar production. Different pretreatments, including physical, KGB extract-mediated treatment, followed by KOH pretreatment, have been applied to produce CNCs using KGB. The presence of CNCs influences the pretreatment of KGB substrate, fungal cellulase production, stability, and sugar recovery in the enzymatic hydrolysis of KGB. Using 1.0% CNCs pretreated KGB-based solid-state fermentation, 33 U/gds FPA and 126 U/gds BGL were obtained at 72 h, followed by 107 U/gds EG at 48 h in the presence of 0.5% CNCs. Further, 42 °C has been identified as the optimum temperature for cellulase production, while the enzyme showed thermal stability at 50 °C up to 20 h and produced 38.4 g/L sugar in 24 h through enzymatic hydrolysis of KGB.

Use of Chrysosporium/carbon nanotubes for preconcentration of ultra-trace cadmium levels from various samples after extensive studies on its adsorption properties.

Carbon nanotubes were used to immobilize Chrysosporium fungus for building an adequate adsorbent to be used as an desirable sorbent for preconcentration and measurement of cadmium ultra-trace levels in various samples. After characterization, the potential of Chrysosporium/carbon nanotubes for the sorption of Cd(II) ions was scrutinized by the aid of central composite design, and comprehensive studies of sorption equilibrium, kinetics and thermodynamic aspects were accomplished. Then, the composite was utilized for preconcentration of ultra-trace cadmium levels, by a mini-column packed with Chrysosporium/carbon nanotubes, before its determination with ICP-OES. The outcomes vouchsafed that (i) Chrysosporium/carbon nanotube has a high tendency for selective and rapid sorption of cadmium ion, at pH 6.1, and (ii) kinetic, equilibrium, and thermodynamic studies showed a high affinity of the Chrysosporium/carbon nanotubes for cadmium ion. Also, the outcomes displayed that cadmium can quantitatively be sorbed at a flow speed lesser than 7.0 mL/min and a 1.0 M HCl solution (3.0 mL) was sufficient to desorbe the analyte. Eventually, preconcentration and measurement of Cd(II) in different foods and waters were successfully accomplished with good accuracy, high precision (RSDs ≤5.65%), and low limit of detection (0.015 µg/L).

Coconut waste valorization to produce biochar catalyst and its application in cellulose-degrading enzymes production via SSF.

Solid waste management and waste valorization are key concerns and challenges around the globe. Solid wastes generated by food industries are found in a diverse variety, are key sources of enormously valuable compounds, and can be effectively transformed into useful products for broad industrial applications. Biomass-based catalysts, industrial enzymes, and biofuels are some of the very prominent and sustainable products that are developed using these solid wastes. The aims of the current study are therefore centered on the multiple valorizations of coconut waste (CWs) to develop biochar as a catalyst and its application in fungal enzyme production in solid-state fermentation (SSF). Biochar as a catalyst using CWs has been prepared via a calcination process lasting 1 h at 500 °C and characterized through X-ray diffraction, Fourier-transformed infrared spectroscopy, and scanning electron microscope techniques. The produced biochar has been implemented for boosting enzyme production through SSF. In addition, studies have been performed on enzyme production with varying time and temperature, and it is found that the maximum 92 IU/gds BGL enzyme could be produced at a 2.5 mg concentration of biochar-catalyst at 40 °C in 72 h.

Adsorption performance of Enterobacter cloacae towards U(VI) ion and application of Enterobacter cloacae/carbon nanotubes to preconcentration and determination of low-levels of U(VI) in water samples.

Keeping the high potential of some microorganisms in adsorption of radionuclides in view, the adsorption properties of Enterobacter cloacae towards uranium were attentively scrutinized, and then it was used for preconcentration of uranium in different samples, using Enterobacter cloacae/carbon nanotube composite. First, using ultrasonic agitation, the effects of operational factors on biosorption of uranium on the inactive Enterobacter cloacae were appraised and modeled by central composite design, and a comprehensive study was performed on the equilibrium, kinetics, thermodynamic, and selectivity aspects of biosorption. The optimization studies along with the evaluations of the adsorption properties revealed that Enterobacter cloacae have a high affinity for fast and selective biosorption of uranium ions, at pH 5.1. Second, the Enterobacter cloacae/carbon nanotube was synthesized, characterized, and utilized for preconcentration of uranium in different samples, using a mini-column packed with the composite. The optimization of operational factors on recovery of uranium, using the central composite design, showed that uranium can be quantitively adsorbed at a sample flow rate lower than 4.5 mL min-1 and the desorption could be accomplished with 3.0 mL HCl 0.6 M solution. Finally, the mini-column was exploited for preconcentration and determination of uranium in different samples. The results revealed the low detection limit (0.015 µg.L-1), high precision (RSDs ≤3.92%), and good accuracy of the proposed procedure.