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Fast-accumulating scientific evidence from many studies has revealed that fruits and vegetables are the main source of bioactive compounds; in most cases, wastes and byproducts generated by the food processing industry present similar or a higher content of antioxidant compounds. In recent years, the ever-growing amount of agricultural and food wastes has raised serious concerns from an environmental point of view. Therefore, there is an increasing interest in finding new ways for their processing toward safely upgrading these wastes for recovering high-value-added products with a sustainable approach. Among food waste, the abundance of bioactive compounds in byproducts derived from tomato suggests possibility of utilizing them as a low-cost source of antioxidants as functional ingredients. This contribution gives an overview of latest studies on the extraction methods of carotenoids from tomato waste, along with an evaluation of their antioxidant activity, as well as their industrial applications.

Substantial progress has been made in algal technologies in past few decades. Initially, microalgae drew the attention of the scientific community as a renewable source of biofuels due to its high productivity over a short period of time and potential of significant lipid accumulation. As of now, a technological upsurge has elaborated its scope in phycoremediation of both organic and inorganic pollutants. The dual role of microalgae—i.e., phycoremediation coupled with energy production—is well established, however, commercially, algal biofuel production is not yet sustainable due to high energy inputs. Efforts are being made to make the algal biofuel economy through modification in the cultivation conditions, harvesting, and extraction of value added products. Recent studies have demonstrated algal biomass production with various types of wastewater and industrial effluents. Similarly, the recent advent of eco-friendly harvesting technologies—such as low-cost green coagulants, electrochemical harvesting, etc.—are energy efficient and economical. Contemporary improvement in efficient lipid extraction from biomass will make algal biodiesel economical. The absolute extraction of all the value added products from algal biomass, either whole cell or lipid extracted biomass, in a complete biorefinery approach will be more economical and eco-friendly.

The present review focuses on the cultivation of algal biomass for generating value-added products (VAP) and to assess their economic benefits and harmful environmental impact. Additionally, the impact of bioreactor designs on the yield of microalgal biomass for VAP is also considered. All these factors are discussed in relation to the impact of microalgae production on the bio-economy sector of commercial biotechnology.

The production of microbial biofuels is currently under investigation, as they are alternative sources to fossil fuels, which are diminishing and their use has a negative impact on the environment. However, so far, biofuels derived from microbes are not economically competitive. One way to overcome this bottleneck is the use of microorganisms to transform substrates into biofuels and high value-added products, and simultaneously taking advantage of the various microbial biomass components to produce other products of interest, as an integrated process. In this way, it is possible to maximize the economic value of the whole process, with the desired reduction of the waste streams produced. It is expected that this integrated system makes the biofuel production economically sustainable and competitive in the near future. This review describes the investigation on integrated microbial processes (based on bacteria, yeast, and microalgal cultivations) that have been experimentally developed, highlighting the importance of this approach as a way to optimize microbial biofuel production process.

Only 8.6% of the global economy follows the principles of the circular economy. Mining and metal extraction processes generate over 90% of global waste, with slags being the major contributor to waste accumulation. Copper slags mostly consist of stable compounds that are safe for the environment, the main concern being the leaching of heavy metals into the ground. The market for using waste copper slags to produce value‐added products is established in the last century and grown to an 800 million dollar market in 2024, with a predicted compound annual growth rate of 5.5% in the following years. However, only 15% of the generated copper slags worldwide are used for commercial purposes. In order to attain complete reusability of copper slags, industrial techniques must be adopted to eliminate threats from heavy metals and other possibly harmful elements. Additionally, it is essential to establish a market that can sustainably handle all quantities of generated slag. This review highlights the properties that make copper slags suitable for producing value‐added products. With the rapid increase in population and urbanization, there is a potential to utilize copper slags for a‐large‐scale construction purposes such as earthworks and buildings. The demand for geotechnical applications and construction materials constantly increases and can absorb the entire quantity of copper slags generated. If this happens, it would mean an achievement of 100% reusability of copper slags in compliance with circular economy principles. Mining and metal extraction processes generate over 90% of global waste. With the rapid increase in population and urbanization, the demand for geotechnical applications and construction materials constantly increases and can absorb the entire quantity of slags generated. If this happens, it would mean an achievement of 100% reusability of slags in compliance with circular economy principles.

Aqueous rechargeable Zn–CO2 batteries are emerging as a promising technology for sustainable energy storage and carbon dioxide (CO2) utilization, owing to their high safety, theoretical capacity, and product diversity. Despite their significant theoretical potential, the application of Zn–CO2 batteries is hindered due to several challenges, including low product‐added value, low current density, poor cycle stability, and excessively high overpotential. These issues hinder the widespread use of Zn–CO2 batteries. Cathode bifunctional catalysts, which can promote the CO2 reduction reaction while lowering the reaction energy barrier for the oxygen evolution reaction, have garnered research interest in recent years. However, a systematic summary is rarely reported. This review mainly focuses on the cathode catalysts of aqueous rechargeable Zn–CO2 batteries, summarizing current research progress in terms of devices, reaction mechanisms, and bifunctional catalysts. This review also discusses existing challenges and prospects, offering enlightenment for the future research of Zn–CO2 batteries.

The North American pawpaw (Asimina triloba (L.) Dunal) is a high-value native specialty fruit crop that offers multiple opportunities for commercial value-added products. A survey was conducted to obtain a better understanding of consumer preferences for pawpaws as fresh and value-added food products. The survey was distributed to 524 individuals who were members of the North American Pawpaw Growers Association, attendees of the 2016 International Pawpaw Conference at Frankfurt, Kentucky, and participants at the 2017 Ohio Pawpaw Festival, Albany, Ohio. Respondents were asked to self-identify their positions (consumers or producers) in the pawpaw market. Those who self-identified as consumers were asked to take the survey. A total of 192 responses were collected. Survey results indicated that the majority of the respondents consume fresh or value-added pawpaw products at least once a year. They reported strong preferences for the flavor and texture of fresh pawpaws. Price, origin, and type of production process had statistically significant impacts on consumers’ purchase preferences. The characteristic that most influenced demand was local production—consumers were willing to pay a premium of $5.20/kg for locally produced pawpaws compared to pawpaws of unknown region of origin. Consumers also preferred certified organic and pesticide-free pawpaws to fruit produced using chemical fertilizers, pesticides, and herbicides. The average price premiums consumers were willing to pay for certified organic and pesticide-free fruits were $4.19 and $3.28/kg, respectively. Providing information about the region of origin, organic and pesticide-free production processes can potentially increase consumer demand for pawpaws and their share of the fresh and value-added fruit market.

Conversion of livestock manure into organic fertilizer is a sustainable strategy in crop production. In contrast to composted manure, the agronomic characteristics of an anaerobic digestion by-product, digestate, have not been well characterized. This study aimed to investigate the effects of digestate and compost, derived from a pilot-scale livestock waste recycling system, on bioactive compounds in tomato fruits. Both field and greenhouse experiments were conducted to compare the effects of these two organic fertilizers with the application of chemical fertilizer. These comparisons were made by evaluating their influence on tomato yield and bioactive compound contents and antioxidant activity of fruits. The experiment included a control (no fertilizer) and three fertilization treatments with the same nitrogen dose: chemical fertilizer, digestate, and compost. The results revealed that the application of digestate and compost yielded similar results in terms of tomato production, surpassing both the chemical fertilizer application and the control group under both field and greenhouse conditions. Fertilization exhibited a significant influence on the bioactive compound contents and antioxidant capacity of the fruits. Furthermore, the application of digestate and compost led to an increase in the concentration of sugars, phenolic compounds, and several organic acids in the fruits while simultaneously reducing the citric acid levels in comparison to the chemical fertilizer treatment. Moreover, the application of both organic fertilizers improved the total phenol and total flavonoid contents in tomato fruits, and the antioxidant capacity in fruits was significantly higher than that of the chemical fertilizer treatment. In conclusion, the application of digestate or compost derived from the livestock waste recycling system reduced use of chemical fertilizers and resulted in higher tomato yields and fruit with considerably superior bioactive compounds. The results suggested that using digestate or compost as an alternative to inorganic fertilizers for tomato cultivation could assist farmers in increasing productivity, improving the content of bioactive compounds in tomato fruit, and promoting agricultural waste management.

In this present work, the absorption of CO 2 in alkyl amines and vegetable oil mixture has been evaluated. The results showed that the absorption is higher in alkyl amines and vegetable oil mixture compared with the aqueous alkyl amines. In addition to that, by employing the greener and non-toxic vegetable oil media, the CO 2 gas has been captured as well as converted into value-added products, such as carbamates of ethylenediamine, diethylenetriamine, and triethylenetetramine. The carbamates have been isolated and characterized by Fourier transform infrared and 1 H and 13 C nuclear magnetic resonance spectroscopic techniques. The formation of these products in precipitate form has not been observed in the case of aqueous medium. Among the various alkyl amine and vegetable oil combinations, triethylenetetramine in coconut oil medium showed the maximum CO 2 capture capacity of 72%. The coconut oil used for the process has been recovered, recycled, and reused for 3 cycles. Thus, this novel scheme seems to be a better alternative to conquer the drawback of aqueous amine-based CO 2 capture as well as for the capture and utilization of the CO 2 gas to gain the value-added products.

Lignocellulosic biomass generated from different sectors (agriculture, forestry, industrial) act as biorefinery precursor for production of second-generation (2G) bioethanol and other biochemicals. The integration of various conversion techniques on a single platform under biorefinery approach for production of biofuel and industrially important chemicals from LCB is gaining interest worldwide. The waste generated on utilization of bio-resources is almost negligible or zero in a biorefinery along with reduced greenhouse gas emissions, which supports the circular bioeconomy concept. The economic viability of a lignocellulosic biorefinery depends upon the efficient utilization of three major components of LCB—cellulose, hemicellulose and lignin. The heterogeneous structure and recalcitrant nature of LCB is main obstacle in its valorization into bioethanol and other value-added products. The success of bioconversion process depends upon methods used during pre-treatment, hydrolysis and fermentation processes. The cost involved in each step of the bioconversion process affects the viability of cellulosic ethanol. The lignocellulose biorefinery has ample scope, but much-focused research is required to fully utilize major parts of lignocellulosic biomass with zero wastage. The present review entails lignocellulosic biomass valorization for ethanol production, along with different steps involved in its production. Various value-added products produced from LCB components were also discussed. Recent technological advances and significant challenges in bioethanol production are also highlighted in addition to future perspectives.