Search Results (2,129)

The pressure on the environment from wastewater has been increasing in line with industrialization and urbanization, thus calling for better and eco-friendly solutions for wastewater treatment. Extremophilic microorganisms, which can grow in extreme conditions including high salinity, acidity, and temperature, can be applied in wastewater bioremediation. This review assesses the various functions of extremophiles, halophiles, thermophiles, alkaliphiles, and acidophiles in the treatment of organic and inorganic pollutants. They are capable of catabolizing a wide range of hazardous chemicals, such as polycyclic aromatic hydrocarbons, phenolic compounds, and heavy metals. Moreover, extremophilic microalgae, like Galdieria sulphuraria, have been effective in nutrient removal, biosorption of heavy metals, and pollutant conversion into valuable biomass. This dual-functioning, therefore, helps not only in wastewater treatment but also in the production of biofuel and biofertilizer, making the process cost-effective. The use of extremophiles in biofilm reactors improves pollutant removal, with less energy input. Extremophilic microorganisms can, therefore, be used to revolutionize wastewater management by providing green solutions to current treatment approaches. This review discusses the existing drawbacks of wastewater treatment along with the additional requirements needed to enhance the capability of bioremediation and potential future research. Full article

Current sustainability challenges for the chemical industry include developing advanced wastewater treatment technologies and transitioning to renewable biomass for more sustainable processes. This study aims to design and develop photoactive colloidal microgels for environmental applications, focusing on the removal of pollutants and the green synthesis of sustainable materials. PNIPAM-based microgels with covalently integrated Rose Bengal as a photosensitizer was synthesized and characterized. The stimuli-responsive colloidal structure of the microgels enhances substrate adsorption and reaction kinetics, surpassing free Rose Bengal due to the local concentration effect provided by the polymeric matrix at the reaction temperature and pH. These materials, designed according to green chemistry principles, enable the sustainable synthesis of 5-hydroxy-2(5H)-furanone, a C4 building block intermediate, achieving over 99% conversion in aqueous media, which is a novel aspect compared to the literature. The removal of Diclofenac from wastewater has been highly efficient, reaching degradation rates of over 99% in 160 min. The photoactive microgels act as efficient photocatalysts, validated under direct solar irradiation, capable of generating singlet oxygen (O₂(¹Δg)) with full recoverability and reusability over multiple cycles. This approach provides a cost-effective eco-friendly solution to economic and environmental challenges in water treatment, as shown by scale-up economic simulations. Full article

Various Higher Education Institutions (HEIs) set themselves goals to become carbon neutral through the implementation of different reduction strategies such as the replacement of fossil-fueled vehicles with electric cars. However, even if all reduction measures are taken, residual GHG emissions will still remain. Therefore, most HEIs have to compensate for the remaining emissions by, for example, buying carbon credits. However, due to growing criticism of carbon credit purchases, HEIs need to explore options for establishing carbon sinks on their own premises to offset their remaining, unavoidable emissions. This study aimed to assess the CO₂ footprint of Hochschule Geisenheim University (HGU) as an exemplary HEI, identify emission hot-spots, and investigate the potential of biomass utilization for achieving carbon neutrality or even negative emissions. The analysis found that HGU’s main emissions were scope 1 emissions, primarily caused by on-site heat supply. The research determined that conversion to a wood chip-based heating system alone was insufficient to achieve climate neutrality, but this goal could be achieved through additional carbon dioxide removal (CDR). By operating a pyrolysis-based bivalent heating system, the study demonstrated that heat demand could be covered while producing sufficient C-sink certificates to transform HGU into the first carbon-negative HEI, at a comparable price to conventional combustion systems. Surplus C-sink certificates could be made available to other authorities or ministries. The results showed that bivalent heating systems can play an important role in HEI transitions to CO₂ neutrality by contributing significantly to the most urgent challenge of the coming decades: removing CO₂ from the atmosphere to limit global warming to as far below 2 °C as possible at nearly no extra costs. Full article

This research identified the optimal scenarios to produce three bioenergy outputs: dual generation (electricity and heat), electricity, and heat in two regions located in the northern part of Costa Rica. Two biomass conversion technologies—boilers and gasification—with 2, 5, and 10 MW production capacities were assessed to ascertain the most suitable technology-capacity pairing for each bioproduct. To this end, a comprehensive financial model was developed to maximize the net present value. Following this, the equilibrium point for biomass supply and demand was ascertained, alongside estimations of the associated costs and energy utility. The findings indicated that the three bioenergy products could be completed within the local energy market at prices below 0.14 USD/kWh, with maximum supply distances of 90 km. The boiler and turbine technology proved most suitable for dual and electricity generation, with capacities ranging between 2 MW and 5 MW, where differentiation was influenced by biomass transportation. Furthermore, heat generation demonstrated financial viability at a capacity of 2 MW. In the evaluation of supply-demand break-even points, a maximum benefit of 26% was observed, with dual production yielding the highest benefits and heat production being the least favorable option due to the costs linked to biomass transportation and the low efficiency of energy transformation. Full article

Basil (Ocimum basilicum L.) is highly sensitive to environmental conditions and is an ideal candidate for cultivation in controlled environment agriculture (CEA). Light-emitting diode technology has become essential in CEA, offering precise control over light intensity, spectrum, and duration. This study investigated how supplemental blue light, far-red light, or their combination influences basil biomass, morphology, texture, and color when added to a white + red light spectrum. Basil ’Prospera’ and ’Amethyst’ were exposed to five light treatments for 14–28 days: white + red at 180 µmol∙m⁻²∙s⁻¹ (W) as the control, and four treatments with an additional 60 µmol∙m⁻²∙s⁻¹ of either white + red (+W₆₀), blue (+B₆₀), far-red (+FR₆₀), or a combination of B and FR (+B₃₀+FR₃₀), for a total photon flux density of 240 µmol∙m⁻²∙s⁻¹. The results demonstrated that +B₆₀ and +W₆₀ light treatments increased leaf thickness by 17–20% compared to the +FR₆₀ treatment. Conversely, texture analysis revealed that +FR₆₀-treated leaves had higher puncture resistance, with ’Amethyst’ and ’Prospera’ requiring 1.57 ± 0.43 N and 1.45 ± 0.35 N of force, respectively, compared to 1.19 ± 0.32 N and 1.1 ± 0.21 N under +B₆₀. These findings suggest that tailored light recipes in CEA can optimize basil quality, allowing growers to modify traits like leaf color, thickness, and toughness. Full article

As a type of sustainable and renewable natural source, biomass-derived 5-hydroxymethyl furfural (HMF) can be converted into high-value chemicals. This study investigated the interactions between silver (Ag) and oxide supports with varied reducibility and their contributions to tuning catalytic performance in the selective oxidation of HMF. Three representatives of manganese dioxide (MnO₂), zirconium dioxide (ZrO₂), and silicon dioxide (SiO₂) were selected to support the Ag active sites. The catalysts were characterized by techniques such as STEM (TEM), Raman, XPS, H₂-TPR, and FT-IR spectroscopy to explore the morphology, Ag dispersion, surface properties, and electronic states. The catalytic results demonstrated that MnO₂ with the highest reducibility exhibited superior catalytic performance, achieving 75.4% of HMF conversion and 41.6% of selectivity for 2,5-furandicarboxylic acid (FDCA) at 120 °C. In contrast, ZrO₂ and SiO₂ exhibited limited oxidation capabilities, mainly producing intermediate products like FFCA and/or HMFCA. The oxidation ability of these catalysts was governed by support reducibility, because it determined the density of oxygen vacancies (Ov) and surface hydroxyl groups (O_OH), and eventually influenced the catalytic activity, as demonstrated by the reaction rate: Ag/MnO₂ (3214.5 mol_HMF·g_Ag⁻¹·h⁻¹), Ag/ZrO₂ (2062.3 mol_HMF·g_Ag⁻¹·h⁻¹), and Ag/SiO₂ (1394.4 mol_HMF·g_Ag⁻¹·h⁻¹). These findings provide valuable insights into the rational design of high-performance catalysts for biomass-derived chemical conversion. Full article

Terminal drought is the major constraint for chickpea production, leading to yield losses of up to 90% in tropical environments. Understanding the morphological, phenological, and physiological traits underlying drought tolerance is crucial for developing resilient chickpea genotypes. This study elucidates the drought-tolerant traits of eight kabuli chickpea genotypes under a controlled environment using polyvinyl chloride (PVC) lysimeters. Terminal drought was imposed after the flowering stage, and the response was assessed against non-stress (well-watered) treatment. Drought stress significantly impacted gas-exchange parameters, reducing the stomatal conductance (16–35%), chlorophyll content (10–22%), carbon assimilation rate (21–40%) and internal carbon concentration (7–14%). Principal component analysis (PCA) indicated three groups among these eight genotypes. The drought-tolerant group included two genotypes (AVTCPK#6 and AVTCPK#19) with higher water use efficiency (WUE), deep-rooted plants, longer maturity, and seed yield stability under drought stress. In contrast, the drought-susceptible group included two genotypes (AVTCPK#1 and AVTCPK#12) that were early-maturing and low-yielding with poor assimilation rates. The intermediate group included four genotypes (AVTCPK#3, AVTCPK8, AVTCPK#24, and AVTCPK#25) that exhibited medium maturity and medium yield, conferring intermediate tolerance to terminal drought. A significantly strong positive correlation was observed between seed yield and key physiological traits (stomatal conductance (gsw), leaf chlorophyll content (SPAD) and carbon assimilation rate (A_sat)) and morphological traits (plant height, number of pods, and root biomass). Conversely, carbon discrimination (Δ¹³C) and intrinsic WUE (iWUE) showed a strong negative correlation with seed yield, supporting Δ¹³C as a surrogate for WUE and drought tolerance and a trait suitable for the selection of kabuli chickpea genotypes for drought resilience. Full article

Hydrothermal carbonization (HTC) is an efficient method for converting lignocellulosic biomass into biofuels. However, traditional Brønsted acid-catalyzed HTC processes face challenges such as high costs and limited catalytic efficiency. In this study, the catalytic carbonization mechanism was investigated within the temperature range of 180–220 °C by analyzing the evolution of functional groups in hydrochar under lanthanide (III)-catalyzed and non-catalyzed conditions. The results indicate that compared to acid catalysis, lanthanide (III) exhibits superior catalytic performance during the low-temperature HTC of cellulose. At 200 °C, lanthanide (III) accelerates the conversion of cellulose into char microparticles, while at 220 °C, it promotes the complete hydrolysis of cellulose into char microparticles enriched with furan structures. Characterization analyses revealed that lanthanide (III) enhances the formation of HMF (5-hydroxymethylfurfural), suppresses its conversion to LA (levulinic acid), promotes the polymerization of HMF into char microparticles, and indirectly accelerates the hydrolysis of cellulose into oligosaccharides. Full article

This article provides an overview of various microwave-assisted techniques, such as microwave-assisted extraction (MAE), microwave-assisted organic synthesis (MAOS), microwave-assisted pyrolysis (MAP), microwave-assisted hydrothermal treatment (MAHT), microwave-assisted acid hydrolysis (MAAH), microwave-assisted organosolv (MAO), microwave-assisted alkaline hydrolysis (MAA), microwave-assisted enzymatic hydrolysis (MAEH), and microwave-assisted fermentation (MAF). Microwave-assisted biomass pretreatment has emerged as a promising method to improve the efficiency of biomass conversion processes, in particular microwave-assisted pyrolysis (MAP). The focus is on microwave-assisted pyrolysis, detailing its key components, including microwave sources, applicators, feedstock characteristics, absorbers, collection systems, and reactor designs. Based on different studies reported in the literature and a mathematical model, a mechanical design of a microwave oven adapted for pyrolysis is proposed together with a computer-aided design and a finite element analysis. The semi-continuous system is designed for a 40 L capacity and a power of 800 W. The material with which the vessel was designed is suitable for the proposed process. The challenges, opportunities, and future directions of microwave-assisted technologies for the sustainable use of biomass resources are presented. Full article

Feedstock plants for biofuel production can be cultivated on polluted sites that are unsuitable for edible crop production. This approach combines environmental restoration and renewable energy production, therefore enhancing the economic viability of plant-derived biofuels. Previous studies have indicated that exposure to environmental pollutants may elevate lignin levels in exposed plants, potentially impacting the biomass digestibility and the efficiency of bioethanol conversion. In this study, we investigated the impact of the antimicrobial agent chlortetracycline on lignin biosynthesis in the reference organism Arabidopsis thaliana. Toxicity testing showed that exposure to chlortetracycline significantly reduced plant growth at concentrations above 2.5 mg L⁻¹. Using Fourier-transform infrared spectroscopy (FTIR) analysis, we observed a significant increase in the lignin signature, ranging from 16 to 40%, in plants exposed to chlortetracycline as compared to non-exposed control plants. Transcriptomic analysis (RNA sequencing) was conducted to determine the molecular basis of plant response to chlortetracycline, revealing significant enrichment of several genes involved in lignin biosynthesis and the phenylpropanoid pathway, including cinnamyl alcohol dehydrogenase and peroxidases. Exposure to chlortetracycline also resulted in the overexpression of genes involved in the metabolism of xenobiotic compounds, including cytochrome P450 monooxygenases, glutathione S-transferases, and glycosyltransferases. Chlortetracycline also induced several genes involved in plant response to stress and defense mechanisms, including transcription factors (e.g., WRKY, MYB, AP2/ERF families), pathogenesis-related proteins, and genes involved in stress signaling. These results suggest that the antibiotic chlortetracycline triggers multiple stress responses in A. thaliana, which may cause changes in lignin biosynthesis, reductions in plant growth, increases in the lignin content, and induction of defense metabolic pathways. Full article

Strategic deep tillage (SDT) practices, such as soil mixing following the application of soil amendments, are promising approaches to alleviate topsoil water repellence and other subsoil constraints and improve crop productivity. However, there is a lack of knowledge on the effect of SDT on soil water dynamics, especially under water-limited environments. This study evaluates the effects of clay incorporation, soil inversion and deep soil mixing on soil water infiltration, surface evaporation rates, soil water storage and subsequent impacts on the below and aboveground growth of wheat (Triticum aestivum L. var Scepter) in controlled environments. Results show that soil mixing significantly improved water infiltration compared to an untreated control. Clay incorporation exhibited the highest bare soil surface evaporation rates immediately and two years post-tillage, leading to substantial water losses under warm and dry ambient conditions. Despite improving soil water storage in deeper layers, high evaporation rates in clay-incorporated soils negatively impacted wheat growth, with reduced shoot biomass and root length density. Conversely, soil inversion and mixing-only treatments demonstrated balanced improvements in water infiltration, soil water use, and wheat shoot biomass. These findings underscore the trade-offs associated with SDT practices, particularly in managing soil water loss and crop productivity in water-limited environments. This study also highlights the need for the careful selection of SDT for soil amelioration strategies tailored to soil types and climatic conditions to enhance agricultural productivity and sustainability. Full article

For efficient production of microbial lipids also known as single cell oil (SCO), selection of favorable growth conditions including the substrate for maximum conversion into storage lipids is imperative. Utilization of lignocellulosic biomass for microbial oil production is a promising approach as it is renewable, sustainable, and available in abundance, with a significant quantity of fermentable sugars. Because of their intricate structure and biomolecular composition, lignocellulosic substrates exhibit high recalcitrance and demand specific pretreatments to release the fermentable sugars. However, pretreating the lignocellulosic substrate not only produces assimilable sugars but also various fermentation inhibitors that can significantly impede microbial growth and/or lipogenesis. Therefore, in this review, we discuss different inhibitors present in the lignocellulosic hydrolysates, and the impact on oleaginous microbial growth and metabolic activity, particularly concerning lipid production. Furthermore, the mode of inhibition of the various inhibitors and potential strategies to detoxify these are discussed in this review. Full article

Traditional anaerobic digestion (AD) technology continues to have severe limitations in terms of complicated substrate degradation efficiency and methane production. This study optimizes the AD system using corn straw and cattle manure as substrates by introducing an exogenous N-Hexanoyl-L-Homoserine lactone (C6-HSL) signaling molecule in concert with an applied external voltage of 0.8 V, systematically investigating its impact on methanogenic performance and microbial community dynamics. The results show that the combined regulation significantly increased methane production (by 29.74%) and substrate utilization rate (by 74.73%) while preventing acid inhibition and ammonia nitrogen inhibition. Mechanistic analysis revealed that the external voltage enhanced the system’s electrocatalytic activity, while the C6-HSL signaling molecule further facilitated the electron transfer efficiency of the biofilm on the electrode. The combined regulation notably enriched hydrogenotrophic methanogens (with Methanobacterium predominating on the cathode and Methanobrevibacter in the digestate), establishing a stable metabolic cooperative network on both the electrode and in the digestate, optimizing the hydrogenotrophic methanogenesis pathway, and enhancing the synergistic effects among microbial communities and system robustness. This study uncovers the synergistic enhancement mechanism of C6-HSL and external voltage, providing new technological pathways and theoretical support for the efficient conversion of low-quality biomass resources and the production of clean energy. Full article

Soil cadmium pollution poses significant environmental risks, prompting global concern. Previous studies have demonstrated that 24-epibrassinolide (Brs) can enhance plant photosynthesis, thereby potentially improving the efficiency of soil cadmium remediation by increasing biomass. Therefore, this study investigated the use of Brs to enhance Cd remediation by willow and alfalfa. After four months, we analyzed soil physicochemical properties, plant physiological and biochemical responses, biomass, Cd fractionation, plant Cd concentrations, and bioaccumulation factor (BCF). Willow and alfalfa cultivation without Brs increased soil pH and carbonates, reduced the exchangeable Cd fractionation, and increased Cd bound to Fe-Mn oxides and organic matter (p < 0.05). Conversely, Brs application increased soil total acids, increasing the bioavailable Cd (p < 0.05). Willow grown for four months accumulated Cd in leaves, stems, and roots at concentrations of 141.83−242.75, 45.91−89.66, and 26.73−45.68 mg kg⁻¹, respectively, with leaf BCF ranging from 14.53 to 24.88. After five months, leaves of willow planted in Cd-contaminated soil (9.65 mg kg⁻¹) contained 187.90−511.23 mg kg⁻¹ Cd, with BCFs of 19.25−52.38. Brs also increases plant biomass by improving photosynthesis, detoxification, and antioxidant defenses. Treatments with Brs and willow extracted 1.57−1.81 times more Cd (0.56−1.37 mg pot⁻¹) than without Brs (0.31−0.87 mg pot⁻¹). This study offers guidelines for Cd phytoremediation and highlights an effective strategy to enhance Cd accumulation. Full article