Search Results (8,147)

The biotechnological conversion of CO₂ to biomethane represents an energy-efficient, environmentally friendly, and sustainable approach within the waste-to-energy cycle. This process, in which CO₂ and H₂ are converted to biomethane in anaerobic bioreactors, is referred to as hydrogenotrophic biomethane production. While several studies have investigated hydrogenotrophic biomethane production, there is a lack of research comparing flocculent and granular sludge inoculum in continuously operated systems fed with a gas substrate. Both granular and flocculent sludge possess distinct advantages: granular sludge offers higher density, stronger microbial cohesion, and superior settling performance, whereas flocculent sludge provides faster substrate accessibility and more rapid initial microbial activity. In this study, two UASB (Upflow Anaerobic Sludge Blanket) reactors operated under mesophilic conditions were continuously fed with synthetic off-gas composed of pure H₂ and CO₂ in a 4:1 ratio and were compared in terms of microbial community shifts and their effects on hydrogenotrophic biomethane production. Biomethane production reached 75 ± 2% in the granular sludge reactor, significantly higher than the 64 ± 1.3% obtained with flocculent sludge. Although hydrogen consumption did not differ significantly, the granular sludge reactor exhibited higher CO₂ removal efficiency. Microbial analyses further revealed that granular sludge was more effective in supporting methanogenic archaea under conditions of gas substrate feeding. These findings offer advantageous suggestions for improving biogas production, enhancing waste gas management, and advancing sustainable energy generation. Full article

The production of alumina produces red mud (RM), a highly alkaline solid waste. The majority of it is disposed of in landfills, which seriously pollutes the environment. It needs to be recycled and handled with care to protect the environment. RM is a promising raw material for wastewater and waste gas treatment owing to its high alkalinity and abundant metal compounds. It can efficiently remove diverse pollutants while facilitating large-scale utilization of RM resources. Reviews of the use of RM resources to create catalysts for environmental governance are, nevertheless, scarce. Therefore, this paper analyzes and summarizes the pertinent research on RM-based catalysts to remove pollutants from the environment based on journal literature related to RM resource utilization from 2015 to 2025. This study reviews the application of RM-based catalysts for degrading pollutants in wastewater and exhaust gases via advanced oxidation processes (AOPs)—including photocatalysis, Fenton-like catalysis, ozonation catalysis, and persulfate catalysis—as well as catalytic oxidation, chemical looping combustion (CLC), and selective catalytic reduction (SCR). The paper emphasizes the analysis of modification strategies and catalytic mechanisms of RM-based catalysts in environmental remediation and examines the environmental risks and corresponding mitigation measures related to their preparation from RM resources. Finally, it outlines that future research should prioritize green, low-energy modification processes; catalytic systems for the synergistic removal of multiple pollutants; and efficient, recyclable separation and recovery technologies. These directions aim to promote the sustainable application of RM in large-scale environmental remediation and to achieve the integrated advancement of resource utilization and ecological protection. Full article

Preformed porous media (PPM) technology has emerged as a transformative approach to enhance heat and mass transfer in vacuum freeze-drying (VFD) of agricultural and food products. This review systematically analyzes recent advances in PPM research, with particular focus on spray freeze-drying (SFD) as the dominant technique for precision pore architecture control. Empirical studies confirm PPM’s efficacy: drying time reductions of 20–50% versus conventional VFD while improving product quality (e.g., 15% higher ginsenoside retention in ginseng, 90% enzyme activity preservation). Key innovations include gradient porous structures and multi-technology coupling strategies that fundamentally alter transfer mechanisms through: resistance mitigation via interconnected macropores (50–500 μm, 40–90% porosity), pseudo-convection effects enabling 30% faster vapor removal, and radiation enhancement boosting absorption by 40–60% and penetration depth 2–3 times. While inherent VFD limitations (e.g., low thermal conductivity) persist, we identify PPM-specific bottlenecks: precision regulation of pore structures (<5% size deviation), scalable fabrication of gradient architectures, synergy mechanisms in multi-field coupling (e.g., microwave-PPM interactions). The most promising advancements include 3D-printed gradient pores for customized transfer paths, intelligent monitoring-feedback systems, and multiscale modeling bridging pore-scale physics to macroscale kinetics. This review provides both a critical assessment of current progress and a forward-looking perspective to guide future research and industrial adoption of PPM-enhanced VFD. Full article

Anaerobic digestion piggery effluent (ADPE), dark brown with high turbidity and ammonium, inhibits algal growth and requires pretreatment for cultivation. This study compared various physical/biological pretreatment methods for microalgae cultivation. The results showed that the strategy of 10%ADPE fungal cultivation (10%AF) pretreatment and subsequent microalgae cultivation achieved maximum specific growth rate (0.094 d⁻¹) with productivity (0.014 g L⁻¹ d⁻¹) and significant nutrient removal: 100% ammonium nitrogen, 99% total nitrogen, 63% total phosphorus, 91% chemical oxygen demand. However, the pathogenic fungus used poses safety risks, requiring future screening of eco-friendly alternatives. This study demonstrated that the strategy could be a promising approach to algal biomass production and nutrient removal from ADPE. Full article

Foam acidification is often employed as a clean and efficient method to remove blockages from wells and promote oil and gas production. In order to effectively control the diffusion of H⁺ in the acid solution into the rock surface, reduce the acid–rock reaction rate, and achieve deep acidification, a foam-retarding acid with foam stability, temperature and salt resistance, and excellent retarding performance was prepared by studying the synergistic effect of the foaming agent and foam stabilizer. ZG-A was used as the foaming agent, and ZG-B was added as a foam stabilizer to achieve foam stabilization. When the ZG-A/ZG-B ratio was 0.67%/0.33%, the foam exhibited the best comprehensive performance. By measuring and comparing the acid–rock reaction rate under different conditions, the results showed that the average acid–rock reaction rate of the 10% compound acid was 1.412 × 10⁻³ mg/(cm²·s), while the average acid–rock reaction rate of the foam-retarding acid system was reduced to 6.622 × 10⁻⁵ mg/(cm²·s), representing a reduction of two orders of magnitude, and the slow rate reached 95.31%. Foam fluid diversion experiments were carried out on cores with different permeabilities. The results showed that the foam could increase the diversion flow rate of low-permeability cores and reduce the diversion flow rate of high-permeability cores. Thus, the foam fluid could be uniformly propelled in cores with different permeabilities. Based on this principle, foam acid acidification can increase the amount of acid injection into the low-permeability layer and reduce the amount of acid absorption in the high-permeability layer, thereby improving the acidification effect. Full article

Understanding surface charge behavior is essential for improving ion separation during lithium brine treatment. This paper investigates the performance of a three-compartment electrodialysis system designed for the selective removal of divalent cations (Mg²⁺ and Ca²⁺). The relationship between zeta potential and the recovery of Li⁺, Na⁺, and K⁺ is analyzed. Zeta potential measurements at various pH values showed that Mg(OH)₂ particles maintained a positive charge. The system facilitated the precipitation of Mg(OH)₂ and Ca(OH)₂ via electrochemically generated OH⁻ ions. The specific electrical energy consumption was evaluated for each operating condition. The results showed that the zeta potential of the precipitates was affected by both the current density and temperature. This influenced lithium losses due to brine entrapment within the precipitated solids. At 600 A/m² and 50 °C, more than 99% of Mg²⁺ and Ca²⁺ were removed, and more than 90% of lithium was recovered, with a specific electric energy consumption of 2.58 kWh per kilogram of Li recovered. The system also generates HCl as a valuable by-product, which improves the sustainability of the process. This study provides a new framework for improving the energy efficiency of lithium purification from brines and lithium recovery. Full article

This study presents a general overview of the important problem of pharmaceutical pollutants, aiming to draw attention to the global danger they represent and the need for concrete solutions for their remediation. Here, we summarize the available advanced knowledge on the occurrence and fate of pharmaceutical residues in the environment, particularly in water effluents, since they need a special approach when one takes into account the increasing consumption of medicines by both humans and animals, that might be discharged in aqueous systems and bio-accumulated in aquatic flora and fauna. This review details the presence of pharmaceutical wastes in water sources; their trajectories from production to consumption and release in household taps; their concentrations in natural water; methods for monitoring them; their risks; and their worldwide impacts. Adequate methods and advanced removal techniques for selected contaminants or classes of pharmaceutical compounds are discussed, together with their remediation potential and strategies. Local and global limiting proposals for these types of contaminants and concrete solutions for their remediation are recommended. Full article

The growing depletion of global phosphorus reserves underscores the urgent need for sustainable and circular nutrient recovery solutions. Rich in phosphorus, piggery wastewater represents not just a waste stream but a valuable resource. In this study, we explore an innovative approach by recovering alginate-like exopolymers (ALE) from activated sludge (AS) and utilizing them to produce biosorbent hydrogel beads capable of removing phosphorus directly from real piggery wastewater. The ALE extraction process yielded approximately 175 $\mathrm{m}\mathrm{g} {\mathrm{V}\mathrm{S}}_{\mathrm{A}\mathrm{L}\mathrm{E}}/\mathrm{g}{\mathrm{V}\mathrm{S}}_{\mathrm{s}\mathrm{l}\mathrm{u}\mathrm{d}\mathrm{g}\mathrm{e}}$, highlighting the potential of wastewater biomass as a source of functional biopolymers. Adsorption experiments revealed phosphorus removal efficiencies approaching 80%, with capacities ranging from 0.68 to 1.18 mgP/gVS_ALE. Structural and chemical characterizations confirmed both the successful adsorption of phosphorus and the stability of the biosorbent post-treatment. This work demonstrates a dual benefit: the recovery of critical nutrients and the transformation of wastewater-derived materials into value-added biosolids. By integrating phosphorus capture and biosorbent production, the approach offers a cost-effective and environmentally responsible pathway toward nutrient recycling and wastewater valorization. Full article

Methanol steam reforming (MSR) represents a highly promising pathway for sustainable hydrogen production due to its favorable hydrogen-to-carbon ratio and relatively low operating temperatures. The performance of the MSR process is strongly dependent on the selection and rational design of catalysts, which govern methanol conversion, hydrogen selectivity, and the suppression of undesired side reactions such as carbon monoxide formation. Moreover, advancements in reactor configuration and thermal management strategies play a vital role in minimizing heat loss and enhancing heat and mass transfer efficiency. Effective carbon monoxide removal technologies are indispensable for obtaining high-purity hydrogen, particularly for applications sensitive to CO contamination. This review systematically summarizes recent progress in catalyst development, reactor design, and gas purification technologies for MSR. In addition, the key technical challenges and potential future directions of the MSR process are critically discussed. The insights provided herein are expected to contribute to the development of more efficient, stable, and scalable MSR-based hydrogen production systems. Full article

This study compared the effectiveness of the Sequencing Batch Biofilter Granular Reactor (SBBGR) plant with and without the integration of ozone (BIO-CHEM process) in the remediation of medium-aged landfill leachate. Special attention is given to the removal of per- and polyfluoroalkyl substances (PFAS) as a group of bioaccumulative and persistent pollutants. The findings highlight the high SBBGR performance under biological process only for key wastewater contaminants, with 82% for chemical oxygen demand (COD), 86% for total nitrogen, and 98% for ammonia. Moderate removal was observed for total (TSS) and volatile (VSS) suspended solids (41% and 44%, respectively), while phosphorus and colour removal remained limited. Remarkably, the SBBGR process achieved complete removal of long-chain PFAS, while its performance declined for shorter-chain PFAS. BIO-CHEM process significantly improved COD (87.7%), TSS (84.6%), VSS (86.7%), and colour (92–96%) removal. Conversely, ozonation led to an unexpected increase in the concentrations of several PFAS in the effluent, suggesting ozone-induced desorption from the biomass. SBBGR treatment was characterised by a low specific sludge production (SSP) value, i.e., 5–6 times less than that of conventional biological processes. SSP was further reduced during the application of the BIO-CHEM process. A key finding of this study is a critical challenge for PFAS removal in this combined treatment approach, different from other ozone-based methods. Full article

Background: The skin microbiome plays a key role in maintaining skin health, and its composition can be influenced by cosmetic treatments. This study aimed to investigate the effects of SMART DNA Therapy treatment on facial skin microbiome composition, with specific focus on changes in commensal and pathogenic bacterial populations following multi-component anti-aging intervention. Methods: This clinical study included 10 Caucasian female participants aged 28–50 years (Clinical trial registration number: 0406/2023). Each participant received three Retix.C SMART DNA THERAPY treatments at 14-day intervals over 6 weeks. The protocol included three phases: chemical peeling with ferulic acid, peptide microinjections for DNA repair, and home-care products with antioxidants. Bacterial samples were collected from forehead and cheek skin before treatment and 2 weeks after the final treatment. Samples were analyzed using bacterial culture and PCR methods. Results: After treatment, the skin microbiome showed beneficial changes with increased numbers of helpful bacteria and elimination of harmful bacteria: complete removal of Cutibacterium acnes and Staphylococcus aureus was observed, Staphylococcus epidermidis and other beneficial bacteria increased on both forehead and cheek areas. Overall bacterial diversity decreased, and participants exhibited more similar microbiome patterns after treatment. Conclusions: SMART DNA Therapy treatment successfully modified the skin microbiome by increasing protective bacteria and eliminating pathogenic species. The treatment may support skin health through microbiome modulation and the potential antioxidant effects of its active ingredients, although these were not directly assessed in this study. Full article

In rural Ghana, limited access to affordable, clean cooking fuels drives the need for decentralised waste-to-energy solutions. Anaerobic co-digestion (AcoD) offers a viable route for transforming organic residues into renewable energy, with the added benefit of improved process stability resulting from substrate synergy. This study aims to evaluate the technical feasibility and stabilisation challenges of AcoD, using locally available fruit waste and beet molasses at a secondary school in Bedabour (Ghana). Biological methane potential (BMP) assays of different co-digestion mixtures were conducted at two inoculum-to-substrate (I/S) ratios (2 and 4), identifying the highest yield (441.54 ± 45.98 NmL CH₄/g VS) for a mixture of 75% fruit waste and 25% molasses at an I/S ratio of 4. Later, this mixture was tested in a 6 L semi-continuous AcoD reactor. Due to the high biodegradability of the substrates, volatile fatty acid (VFA) accumulation led to acidification and process instability. Three low-cost mitigation strategies were evaluated: (i) carbonate addition using eggshell-derived sources, (ii) biochar supplementation to enhance buffering capacity, and (iii) the integration of a bioelectrochemical system (BES) into the AcoD recirculation loop. The BES was intended to support VFA removal and enhance methane recovery. Although they temporarily improved the biogas production, none of the strategies ensured long-term pH stability of the AcoD process. The results underscore the synergistic potential of AcoD to enhance methane yields but also reveal critical stability limitations under high-organic-loading conditions in low-buffering rural contexts. Future implementation studies should integrate substrates with higher alkalinity or adjusted organic loading rates to ensure sustained performance. These findings provide field-adapted insights for scaling-up AcoD as a viable renewable energy solution in resource-constrained settings. Full article

This study aimed to evaluate residue changes in flubendiamide and tebufenozide during the processing of whole grain into milled rice, cooked rice, and rice cake, and to calculate their processing factors (PFs). For the processing study, pesticides were applied at three times the recommended rate based on Korea’s good agricultural practice (GAP), and processed products were prepared using conventional methods. Residual pesticide analysis was performed using a modified QuEChERS method and LC-MS/MS. The residue analysis method was validated based on parameters including LOQ, linearity, and accuracy at the LOQ, 10LOQ, and MRL levels, with the LOQ set at 0.01 mg/kg for all samples. During milling, which removes the hull, more than 90% of the pesticide residues were eliminated. Additional reductions exceeding 50% were observed during cooking and rice cake processing. All PFs, except for those in the hulls, were less than 1, indicating that processing reduces pesticide levels. Despite the use of threefold the GAP rate, the %ADI values for all processed products remained below 1%, suggesting negligible dietary risk. These findings provide scientific evidence supporting the safety of processed rice products regarding pesticide residues and highlight the importance of considering processing effects in dietary exposure assessments. Full article

The presence of galena, sphalerite (cleiophane), and Carbonaceous Material (CM) in sulphide ore complicates the application of a direct-differential flotation flowsheet due to increased mutual interactions between both marketable concentrates and final tailings. Flotation tests, measurements of electrokinetic (zeta) potential, adsorption of sulphydric collectors, and colorimetric indicators were employed to elucidate the cause-and-effect relationships underlying the reduction in contrast of the flotation properties of galena and cleiophane surfaces. It was established that galena and cleiophane exhibit comparable flotation responses when using diesel oil within a pH range of 6–8. While high galena recovery is anticipated, the similar recovery of cleiophane is attributed to the ZnS zeta potential approaching zero in this pH interval. Experimental results demonstrated a distinct difference in the flotation behavior of galena and cleiophane, both with natural surface oxidation and following the removal of sulphoxy films. The application of Carbonaceous Material depressants derived from wood processing by-products (lignin-sulphonates) resulted in a significant decrease in sphalerite recovery. Although the flotation rate constant for Carbonaceous Material in the presence of lignin-sulphonate-based depressants decreases, the overall recovery to concentrate increases over time. The implementation of a bulk-differential flowsheet, involving the preliminary removal of CM prior to the bulk Pb-Zn flotation of lead-zinc sulphide ore, has been demonstrated to be effective. Full article

The consistent quality control of ultrapure water (UPW) in semiconductor manufacturing depends on removing trace organonitrogen compounds such as urea. Due to its high solubility, chemical stability, and neutral polarity, urea is inadequately removed by conventional processes. Even at low concentrations, it elevates total organic carbon (TOC) and reduces electrical resistivity. The use of reclaimed water as a sustainable feed stream amplifies this challenge because its nitrogen content is variable and persistent. Conventional methods such as reverse osmosis, ultraviolet oxidation, and ion exchange remain limited in treating urea due to its uncharged, low-molecular-weight nature. This review examines the performance and limitations of these processes and explores electrochemical oxidation (EO) as an alternative. Advances in EO are analyzed with attention to degradation pathways, electrode design, reaction selectivity, and operational parameters. Integrated systems combining EO with membrane filtration, adsorption, or chemical oxidation are also reviewed. Although EO shows promise for selectively degrading urea, its application in UPW production is still in its early stages. Challenges such as low conductivity, byproduct formation, and energy efficiency must be addressed. The paper first discusses urea in reclaimed water and associated removal challenges, then examines both conventional and emerging treatment technologies. Subsequent sections delve into the mechanisms and optimization of EO, including electrode materials and operational parameters. The review concludes with a summary of main findings and a discussion of future research directions, aiming to provide a comprehensive foundation for validating EO as a viable technology for producing UPW from reclaimed water. Full article