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Background Plastic is widely utilized in packaging, frameworks, and as coverings material. Its overconsumption and slow degradation, pose threats to ecosystems due to its toxic effects. While polyhydroxyalkanoates (PHA) offer a sustainable alternative to petroleum-based plastics, their production costs present significant obstacles to global adoption. On the other side, a multitude of household and industrial activities generate substantial volumes of wastewater containing both organic and inorganic contaminants. This not only poses a threat to ecosystems but also presents opportunities to get benefits from the circular economy. Main body of abstract Production of bioplastics may be improved by using the nutrients and minerals in wastewater as a feedstock for microbial fermentation. Strategies like feast-famine culture, mixed-consortia culture, and integrated processes have been developed for PHA production from highly polluted wastewater with high organic loads. Various process parameters like organic loading rate, organic content (volatile fatty acids), dissolved oxygen, operating pH, and temperature also have critical roles in PHA accumulation in microbial biomass. Research advances are also going on in downstream and recovery of PHA utilizing a combination of physical and chemical (halogenated solvents, surfactants, green solvents) methods. This review highlights recent developments in upcycling wastewater resources into PHA, encompassing various production strategies, downstream processing methodologies, and techno-economic analyses. Short conclusion Organic carbon and nitrogen present in wastewater offer a promising, cost-effective source for producing bioplastic. Previous attempts have focused on enhancing productivity through optimizing culture systems and growth conditions. However, despite technological progress, significant challenges persist, such as low productivity, intricate downstream processing, scalability issues, and the properties of resulting PHA. Graphical abstract

Succinic acid (SA) is one of the top platform chemicals with huge applications in diverse sectors. The presence of two carboxylic acid groups on the terminal carbon atoms makes SA a highly functional molecule that can be derivatized into a wide range of products. The biological route for SA production is a cleaner, greener, and promising technological option with huge potential to sequester the potent greenhouse gas, carbon dioxide. The recycling of renewable carbon of biomass (an indirect form of CO 2 ), along with fixing CO 2 in the form of SA, offers a carbon-negative SA manufacturing route to reduce atmospheric CO 2 load. These attractive attributes compel a paradigm shift from fossil-based to microbial SA manufacturing, as evidenced by several commercial-scale bio-SA production in the last decade. The current review article scrutinizes the existing knowledge and covers SA production by the most efficient SA producers, including several bacteria and yeast strains. The review starts with the biochemistry of the major pathways accumulating SA as an end product. It discusses the SA production from a variety of pure and crude renewable sources by native as well as engineered strains with details of pathway/metabolic, evolutionary, and process engineering approaches for enhancing TYP (titer, yield, and productivity) metrics. The review is then extended to recent progress on separation technologies to recover SA from fermentation broth. Thereafter, SA derivatization opportunities via chemo-catalysis are discussed for various high-value products, which are only a few steps away. The last two sections are devoted to the current scenario of industrial production of bio-SA and associated challenges, along with the author's perspective.

More than half of the world's population consumes rice as their primary food. The majority of rice production is concentrated in Asia, with the top 10 rice-growing countries accounting for 84% of the world's total rice cultivation. However, rice production is also strongly linked to environmental changes. Among all the global sources of greenhouse gas (GHG) emissions, paddy cultivation stands out as a significant contributor to global methane (CH ) and nitrous oxide (N O) emissions. This contribution is expected to increase further with the projected increase of 28% in global rice output by 2050. Hence, modifications to rice management practices are necessary both to increase yield and mitigate GHG emissions. We investigated the effect of seedling treatment, soil application, and foliar application of a methane-derived microbial biostimulant on grain yield and GHG emissions from rice fields over three seasons under 100% fertilizer conditions. Further, microbial biostimulant was also tested under 75% nitrogen (N) levels to demonstrate its effect on grain yield. To understand the mechanism of action of microbial biostimulant on crop physiology and yield, a series of physiological, transcript, and metabolite analyses were also performed. Our three-season open-field studies demonstrated a significant enhancement of grain yield, up to 39%, with a simultaneous reduction in CH (31%-60%) and N O (34%-50%) emissions with the use of methane-derived microbial biostimulant. Under 75% N levels, a 34% increase in grain yield was observed with microbial biostimulant application. Based on the physiological, transcript, and metabolite analyses data, we were further able to outline the potential mechanisms for the diverse synergistic effects of methane-derived microbial biostimulant on paddy, including indole-3-acetic acid production, modulation of photosynthesis, tillering, and panicle development, ultimately translating to superior yield. The reduction in GHG emission and enhanced yield observed under both recommended and reduced N conditions demonstrated that the methane-derived biostimulant can play a unique and necessary role in the paddy ecosystem. The consistent improvements seen across different field trials established that the methane-derived microbial biostimulant could be a scalable solution to intensify rice productivity with a lower GHG footprint, thus creating a win-win-win solution for farmers, customers, and the environment.

Background Fruit peels as a lignocellulosic biomass are rich in sugars and nutrients, thus making them favorable medium for yeast growth and various materials production. This study showed the potential of fuit peels hydrolysate (FPH) as a substrate for single-cell protein (SCP) and bioethanol production, depending on substrate concentration, pH, oxygen availability. Results The highest specific growth rate (0.50 ± 0.01 h − 1 ) was observed at pH 6.5 in non-diluted hydrolysates, which corresponds to ~ 250.0 g L − 1 carbohydrates and 0.2 g L − 1 total nitrogen concentration. The maximal protein production yield (~ 50% by dry weight) was recorded during 24 h cultivation of S. cerevisiae ATCC 13,007 under oxygen-limited conditions at pH 6.5, while the maximal ethanol production (109.00 ± 4.00 g L − 1 ) was observed at 6 h for S. cerevisiae ATCC 9804 and ATCC 13,007 starins under aerobic conditions. The maximal fermentation efficiency (~ 99%) was observed at 24 h cultivation of S. cerevisiae ATCC 13,007 in 2-fold diluted hydrolysate under oxygen-limited conditions at pH 6.5, while the same strain exhibited the highest carbon conversion efficiency (CCE) (~ 56%) during aerobic cultivation in 2-fold diluted hydrolysate at pH 3.0. Conclusion Thus, FPH can serve as a favorable substrate for SCP and bioethanol production using S. cerevisiae strains ATCC 13,007 and ATCC 9804. Nitrogen supplementation and combination with fruit and vegetable processing industries could further enhance SCP production and process efficiency which aligns with circular economic strategy.

The objective of this study was to evaluate the effect of surfactant on disperser homogenization pretreatment for macroalgae (Ulva intestinalis) to enhance biogas production. The macroalgae are subjected to surfactant coupled disperser pretreatment, which enhanced the liquefaction and improved the biomethane production. The outcome of this study revealed that 10,000 rpm at 20 min with a specific energy input of 1748.352 kJ/ kg total solids (TS) are the optimum conditions for surfactant disperser pretreatment (SDP), which resulted in the liquefaction rate of 20.08% with soluble organics release of 1215 mg/L and showed a better result than disperser pretreatment (DP) with a liquefaction rate of 14%. Biomethane production through the SDP method was found to be 0.2 g chemical oxygen demand (COD)/g COD, which was higher than DP (0.11 g COD/g COD). SDP was identified to be a synergetic pretreatment method with an energy ratio and net profit of about 0.91 and 104.04 United States dollars (USD)/ton, respectively.

Microplastics, or plastic particles smaller than 5 mm in size, have become ubiquitous in the environment, found in places ranging from remote deep ocean trenches to minute dust particulates. From the breakdown of larger plastic products and the release of synthetic clothing fibers, these particles enter the ecosystem and cycle through the various components including aquatic, terrestrial, and human systems. Due to their durability, capacity to adhere to other toxic compounds, and potential effects on humans and ecosystems, microplastics have recently risen to the forefront of environmental and health concerns. To address these critical issues, there has been a surge in research related to the microplastics cycle, examining where they originate, how and where they travel, and their environmental and human health impacts. Research on the microplastic cycle is often broken down into its various individual components such as sources, fate, and effect, and further scattered through the literature are focuses on specific environments such as land, oceans, and freshwater, as well as on human health. Here, we review the current state of the literature on the microplastic cycle across its various environmental reservoirs. In-depth examination of the microplastics cycle is necessary for understanding the scope of the problem and developing viable solutions or mitigation strategies, such as reducing plastic production and promoting recycling. Understanding the complex microplastics cycle is an urgent issue that necessitates multidisciplinary research and action.

This study explores integrating Bitcoin mining with lignocellulosic biorefineries to create an additional revenue stream. Profits from mining can help offset internal costs, reduce business expenses, or lower consumer prices. Using sensitivity analysis and Monte Carlo simulations, this study identifies key profitability drivers, such as electricity costs, hardware expenses, starting year, and operational time. Time emerged as an extremely sensitive factor and showed that delaying mining operations significantly raised production costs and the probability of profitable outcomes. In contrast, longer mining durations had a smaller yet sizable impact. Hardware costs, computational efficiency, and electricity prices also strongly influenced the outcomes. The majority of simulated events showed a loss. Moreover, the model showed that the marginal profitability of mining decreases over time. Nonetheless, the model demonstrated that under favourable conditions, it is possible to integrate Bitcoin mining into biorefineries and other productive ventures, thereby allowing for cost recovery using Bitcoin profits. For a biorefinery to mine Bitcoin and maximise cost recovery, it must start early, access low electricity prices, and preserve hardware capital characterised by low expenditure and high revenues. Finally, a discussion about the opportunities, risks, and regulations is highlighted.

Bioenergy with carbon capture, utilization, and storage (BECCUS) is a competent technology with the potential to address global climate change challenges. However, its deployment faces significant hurdles across technological, economic, and policy domains. The production of biofuels including ethanol, methane, butanol, and biogas is accompanied by the release of carbon dioxide (CO 2 ). This CO 2 can be incorporated into organic molecules through various biochemical routes as part of the metabolic mechanisms of carbon absorption. The efficiency of these carbon assimilation pathways can be improved through ongoing developments in metabolic engineering, which can increase the production of valuable bioproducts, improve carbon sequestration, and support efforts to mitigate climate change. The present review recognizes critical avenues for advancing BECCUS, emphasizing market mechanisms, technological innovations, and cross-sector integration in both developed and developing countries such as India. The review recommends policy modifications aimed at establishing a transparent framework related to carbon pricing, emission trading systems, and proper certification mechanisms for biogenic carbon utilization. These modifications, coupled with the integration of renewable energy systems, would not only stimulate BECCUS adoption, but also foster its economic feasibility and sustainability. Additionally, promising technologies such as chemical looping and microalgae-based carbon capture should be technologically scaled up to ensure industrial-level applications. The integration of BECCUS with other sectors is also critical to optimize the impact of this technology on climate change mitigation. Therefore, the present review highlights the need for a robust policy framework, technology-driven innovation, and cross-sector research collaboration to resolve the challenges associated with BECCUS, boost its adoption, and ensure its economic feasibility and environmental sustainability. Moreover, providing regulatory support, augmenting market competitiveness, and aligning research on BECCUS play a transformative role in attaining the goals of the Paris Agreement and promoting environmental sustainability. Graphical Abstract

We introduce triple-controlled orthogonal S -metric type spaces involve triple auxiliary control functions β , μ , & γ , extending the classical controlled S -metric type sitting. Furthermore, we formulate ( α s , ⊥ ) -admissible function & strengthen Wardowski’s contraction principle, designing ( α s − A , ⊥ ) -contractive function fitted to the triple-controlled orthogonal structure. On complete spaces of this kind, we establish fixed-point theorems that ensure existence & uniqueness under natural conditions on the control functions and admissibility. As an application, we show that the main result guarantees a unique solution to a class of fractional differential equations.

We report the semicontinuous, direct (anaerobic sequencing batch reactor operation) hydrogen fermentation of de-oiled jatropha waste (DJW). The effect of hydraulic retention time (HRT) was studied and results show that the stable and peak hydrogen production rate of 1.48 L/L ∗ d and hydrogen yield of 8.7 mL H2/g volatile solid added were attained when the reactor was operated at HRT 2 days (d) with a DJW concentration of 200 g/L, temperature 55 °C, and pH 6.5. Reduced HRT enhanced the production performance until 1.75 d. Further reduction has lowered the process efficiency in terms of biogas production and hydrogen gas content. The effluent from hydrogen fermentor was utilized for methane fermentation in batch reactors using pig slurry and cow dung as seed sources. The results revealed that pig slurry was a feasible seed source for methane generation. Peak methane production rate of 0.43 L CH4/L ∗ d and methane yield of 20.5 mL CH4/g COD were observed at substrate concentration of 10 g COD/L, temperature 30 °C, and pH 7.0. PCR-DGGE analysis revealed that combination of cellulolytic and fermentative bacteria were present in the hydrogen producing ASBR.