Literature has reported antibiotic overuse and the spread of antibiotic-resistant bacteria, which require better wastewater treatment. The influence of reactor hydrodynamics on antibiotic elimination processes and related environmental hazards is yet inadequately comprehended. This study assessed the impact of different flow regimes- plug-flow (PF) and continuous-stirred (CS)-on the elimination of 12 antibiotics (five fluoroquinolones, six sulfonamides, and trimethoprim; 10.0 mu g L-1 each) in anaerobic fixed-bed bioreactors (AnFBR). Analysis of residence time distribution indicated that the PF-AnFBR functioned under almost ideal conditions (Peclet number > 1000; dead volume < 2.5%), but the CS-AnFBR had significant non-idealities, characterized by substantial dead zones (54-72%) and hydraulic short-circuiting. Despite both systems attaining elevated COD removal rates (>94%), the patterns of antibiotic removal varied considerably. Plug-flow settings promoted biodegradation-dominated elimination of sulfonamides and trimethoprim (47-100%), while the continuous-stirred arrangement improved the removal of strongly sorbing fluoroquinolones, primarily through adsorption mechanisms. Ecotoxicity assays showed reduced toxicity to Chironomus sancticaroli after treatment, but increased toxicity was observed for Allonais inaequalis and Ceriodaphnia silvestrii, suggesting the formation of toxic transformation products. The microbial analysis revealed a diverse population in both bioreactors, with key genera such as Aeromonas, Pseudomonas, and Methanothrix cleaving aromatic compounds, playing significant roles in antibiotic biodegradation, and stability in the performance of anaerobic bioreactors. These findings indicate that the hydrodynamic regime is a crucial design component influencing antibiotic behavior and environmental efficiency in anaerobic wastewater treatment.

The increase of antibiotics in aquatic environments, along with the emergence of antibiotic-resistant bacteria, highlights the improvement of wastewater treatment technologies. This study investigates a plug-flow structured anaerobic fixed-bed reactor (PF-AnFBR) for removal nine antibiotics representing different classes—an approach rarely explored in anaerobic systems. By integrating spatially resolved sampling along the reactor bed with advanced kinetic modeling, the study provides the first mechanistic evaluation of antibiotic mixture removal in a PF-AnFBR. COD removal remained high (COD > 97

The role of the fixed-bed in anaerobic structured-bed reactors for biohydrogen production remains paradoxical, as high substrate conversion and bioH2 evolution are typically confined to the initial compartments, yet the bed's complete removal impairs performance. This study investigated the impact of the bed-to-feeding chamber height ratio, proposed as a promising design criterion for adjusting bed height relative to the feeding chamber, on biohydrogen evolution. Four reactors were operated with progressively reduced bed heights while maintaining equivalent operating conditions and geometrical features in the feeding chamber. Results demonstrated that the bed-to-feeding chamber height ratio critically governed fermentation performance. Best-performing condition was achieved by removing one-quarter of the bed zone, which successfully increased the hydrogen flow rate by 91% compared to the conventional anaerobic structured-bed reactor, as well as yielding 30 to 61% higher hydrogen than the other conditions investigated, regardless of the levels of overall organic loading rate and hydraulic retention time applied. The bed-to-feeding chamber height ratios significantly shaped the microbial community structure and metabolic pathways. Higher bed-to-feeding chamber height ratios favored the selection of Enterobacter, driving acetate and biohydrogen production, while lower ratios promoted a predominance of Thermoanaerobacterium and Bacillus, shifting metabolism towards lactic acid production. Spatial and temporal metabolite analyses revealed that the best-performing bed height enabled metabolic versatility, including lactate cross-feeding, which supported high bioH2 yields even under propionic acid accumulation. Finally, this study pioneered the use of the bed-to-feeding chamber height ratio as a potential key design parameter for maximizing

Pig farming relies heavily on antibiotics, many of which are also critical to human medicine, leading to their release into pig manure and swine wastewater. The presence of such compounds in the environment is associated with ecotoxicological effects and the proliferation of antibiotic resistance genes. Therefore, swine wastewater is closely linked to the spread of antimicrobial resistance because it may act as a reservoir, a concentrator and an environmental dissemination route for antibiotics, resistance bacteria or antibiotic resistance genes. This contamination potential will depend on the applied treatment (adequacy and efficiency), which will then determine whether the treated effluent and its value-added byproducts are microbiologically safe. This paper presents the treatment systems for swine wastewater observed from broad literature research. Then, the main technologies that have addressed antimicrobial resistance are discussed from a resistome perspective, accounting for performance and limitations. Overall, priority should be given to improving antimicrobial resistance stewardship and surveillance, fostering the development of innovative antimicrobials, and ensuring effective pig wastewater treatment through engineering solutions that include post-treatment and integrated systems.

Cassava processing wastewater (CPWW) is an inexpensive feedstock that can be used to produce lactic acid (LA) through biotechnological processes. While previous studies have focused on pure culture fermentation, we propose a cheaper solution in which the autochthonous microbial community of the CPWW is used instead. A 32 full factorial design was used to investigate the effects of temperature (25 °C; 30 °C; and 35 °C) and initial fermentation pH (4.5; 5.5; and 6.5) on LA production. The results showed that temperature positively impacted lactic fermentation. LA selectivity was increased under acidic conditions, but initial pH did not affect LA yield and volumetric productivity. Interactions effects were statistically significant, implying that the increase in initial pH reduces the production of LA at higher temperatures, while the opposite occurs at lower temperatures. The best performing condition was 35 °C and pH 4.5, which resulted in a LA selectivity of 0.9 g COD-LA g COD−1. Microbial community analysis revealed that the autochthonous consortium in CPWW was composed mostly of Lactobacillus. The results show that temperature and initial pH can steer the indigenous microbial community from the CPWW towards better LA production.

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants widely detected in wastewater, posing ecological risks and potentially disrupting biological treatment processes. This study assessed the toxicity and biodegradation of nine PPCPs-carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBP), naproxen (NPX), metoprolol (MTP), ciprofloxacin (CIP), sulfamethoxazole (SMX), methylparaben (MPB), and propylparaben (PPB)-using five environmentally relevant bacterial strains. Toxicity assays revealed compound-specific effects, with SMX and CIP exhibiting significant growth inhibition (minimum EC50 values of 2.1 and 0.1 mg L-1 for SMX and CIP, respectively). Biodegradation tests indicated enhanced removal in the presence of glycerol by Sphingomonas sp. achieving fully degradation of the most PPCPs, while Burkholderia sp. and Ochrobactrum sp. fully degraded parabens without cosubstrate addition. An anaerobic fixed-bed biofilm reactor (AFBBR) was employed to evaluate PPCPs removal in a continuous system. Removal efficiencies exceeded 80% for SMX, NPX, MPB, and PPB, while DCF showed the lowest removal (<40%). Ecological risk assessment based on risk quotient using PNEC (predicted no-effect concentration) values revealed substantial risk reduction post-treatment. CBZ and DCF posed moderate risk, while other compounds presented low to negligible risk to aquatic organisms. AFBBR demonstrated high potential to mitigate the environmental impact of PPCPs in wastewater.

Microalgae cultivated in wastewater hold promise as a substrate for biohydrogen (bioH2) production. However, their rigid cell walls pose a challenge to fermentability. In this context, this study evaluated hydrothermal pretreatment with niobium phosphate (NbP) at 100-180 degrees C for 0-70 min, using up to 75 % NbP (relative to the dry weight of microalgal biomass). The hydrothermal pretreatment at 180 degrees C for 10 min with 75 % NbP released 7431 mg total carbohydrates (CHt) L-1, increasing the availability of fermentable substrates in subsequent dark fermentation (DF). When this pretreated biomass was subsequently fermented at pH 5.0 (sample PB5), bioH2 production reached 1.03 mmol H2 mol-1 CHt, with a maximum cumulative output of 0.17 mmol H2 and a CHt conversion efficiency of 83.6 %. In contrast, pH 5.5 and 6.0 reduced bioH2 yields and promoted methanogenic activity, while no pH control resulted in negligible bioH2 evolution. In conclusion, hydrothermal pretreatment with niobium phosphate and pH improvement synergize to enhance hydrogenogenesis, integrating wastewater treatment and renewable biohydrogen production.

The shift toward a low-carbon circular economy requires transforming conventional wastewater and solid waste treatment systems into integrated biorefineries capable of recovering value-added products. Participatory approaches address the complexity of this transition by leveraging stakeholder expertise to guide the selection of feedstocks, technologies, and products suitable for integration into biorefinery systems. This study proposes a novel conceptual biorefinery design developed through participatory workshops and the collaborative process mapping of 33 Brazilian research initiatives focused on agro-industrial and urban-source wastewater and waste streams. The analysis reveals a multi-product landscape dominated by low-value energy outputs, primarily generating biogas, methane, hydrogen, and syngas, followed by medium-value-added products, including volatile fatty acids, fertilizers, and biochar. Conversely, high-value bioproducts (polyhydroxyalkanoates, lactic acid, acetic acid, γ-valerolactone, mycelium-based materials) were identified less frequently. Based on this analysis, seven conceptual integrated biorefinery scenarios originating from local agro-industrial sectors and urban environmental services were proposed by combining: (i) feedstock-based integration, clustering by-products originating from the same production chain and functionally similar wastes from different sources within defined sectors; (ii) technological integration, emphasizing mass/energy integration and process intensification; and (iii) product integration, utilizing a value-oriented cascading logic and zero-waste principles. Finally, although no quantitative Life Cycle Assessment (LCA) was performed, the study presents preliminary LCA modeling for a multifunctional scenario, with decision-support criteria and thresholds for constructing integrated biorefinery scenarios, providing practical guidelines for future multi-product life cycle modeling of these conceptual configurations through a scenario-based application of a five-step LCA decision framework.

This study focused on developing an analytical method to quantify nineteen selected micropollutants (MPs), including pharmaceuticals and personal care products, in complex wastewater matrices. An online solid-phase extraction system coupled with LC–MS/MS was used, and different mobile phase compositions were tested in the chromatographic method. The validated method was subsequently applied to real influent and effluent samples from an anaerobic biological reactor in order to assess MP occurrence and removal behavior. The best results were achieved using a mixture of acetonitrile and methanol (50:50 v:v) with 0.1

This study evaluated the anaerobic valorization of real, non-detoxified sugarcane bagasse-derived pentose liquor. Direct fermentation without nutrients, co-substrate, or buffering was limited, reaching low-to-moderate (37–54%) carbohydrate conversion efficiency at low organic loading rate (OLR < 5.6 kg COD m−3 d−1) levels. Hydrogen yield (HY) was also low (0.63–0.89 mol H2 mol−1 carbohydrateconverted) under these conditions. Increasing pentose liquor concentration up to 0.8 L L−1 and OLR of 30.2 kg COD m−3 d−1 suppressed hydrogen production, coinciding with lactate accumulation and the occurrence of homoacetogenesis. Enhanced fermentation with sucrose, nutrients, buffering, shorter hydraulic retention time (12 h) and 37 °C improved stability and carbohydrate conversion (50–61%) under higher OLR, although HY considerably decreased (0.14–0.35 mol H2 mol−1). Methanogenesis was effective in both single- and two-stage systems, with carbohydrate conversion usually above 95%, COD removal up to 83.5%, methane fractions above 60%, and methane yields reaching 299.8–301 NmL CH4 g−1 CODremoved. Furfural and 5-HMF showed phase-dependent transformation, indicating partial in situ detoxification during anaerobic conversion. Overall, pentose liquor is better valorized through integrated hydrogen–methane recovery than by fermentation alone. Future studies should focus on both applying more effective strategies to buffer the fermentative stage and adopting more conservative approaches (lower OLR) to start up the methanogenic systems.

Antibiotics are micropollutants present in aquatic ecosystems, thus causing serious concerns. The presence of mixotrophic microalgae in wastewater biological treatment systems is important for the removal of those micropollutants. This study evaluated the removal efficiency of five different antimicrobials, sulfamethoxazole, trimethoprim, ofloxacin, ciprofloxacin, and enrofloxacin, in batch and continuous photobioreactors by four different Chlorophyceae strains in consortium with autochthonous bacteria. In a batch system, all strains efficiently removed the 5 antibioticsmainly sulfamethoxazole, enrofloxacin, and ciprofloxacin by Desmodesmus sp. (86 ± 2% average removal) and Chlamydomonas sp. (85 ± 1% average removal). In the continuous system, Chlorella sp. also removed the 5 antibiotics, but with better results for sulfamethoxazole and trimethoprim (54 ± 2% and 57 ± 4% average removals, respectively). In the batch system, the highest removal efficiencies were achieved by Chlamydomonas reinhardtii for organic carbon (95 ± 1%) and nitrogen (89 ± 1%) and by Desmodesmus sp. for inorganic phosphorus (91 ± 6%), whereas in the continuous system, 97% organic carbon were removed by Chlorella sp., and better removal performance for four of the antibiotics compared to the batch system. Therefore, microalgae-bacteria consortia are effective for wastewater biological treatment with antimicrobials, a sustainable treatment alternative. Furthermore, this process contributes to the valorization of residues by simultaneously allowing the production of byproducts, such as organic acids and biohydrogen.

ABSTRACT Optimizing the carboxylate platform during continuous sugarcane vinasse fermentation requires overcoming hydrolytic bottlenecks and steering metabolic pathways. This study investigated kinetic patterns and metabolic flux redirection in response to strategic interventions: lactate and glycerol supplementation and effluent recirculation. First-order modeling revealed that while carbohydrate hydrolysis is the baseline rate-limiting step (kapp = 0.4-1.8 h⁻¹), glycerol co-fermentation triggered a redox-driven “flash consumption” (kapp of 23 h⁻¹), bypassing hydrolytic constraints. Targeted lactate supplementation shifted the mixed-acid profile toward butyrogenesis, generating metabolic-derived alkalinity (pH > 7.0) and preventing acidification. Co-supplementation of glycerol and lactate created a controlled hybrid spectrum of propionate and butyrate. Furthermore, effluent recirculation activated in situ chain elongation via reverse β-oxidation, leveraging endogenous electron donors to double valerate production. Crucially, these strategies governed sulfur dynamics by partitioning toxicity between gaseous H2S or dissolved sulfide based on environment buffering. Principal Component Analysis (PCA) revealed that these interventions do not merely increase yields but deterministically restructure the microbial metabolic network. These findings provide a robust, kinetic-based framework for scaling up stable and selective sugarcane biorefineries.

Fermented sugarcane vinasse is a volatile fatty acids-rich wastewater with great potential to supply electrons in microbial electrolysis cells (MEC). This work reports the hydrogen production in a single-chambered MEC started-up with voltage of 0.8 V at 37 degrees C using activated sludge as inoculum. Electroactive microbes were established with current production of 0.2 +/- 0.07 A m-2 and consequent hydrogen production, reaching 90% of molar fraction of hydrogen and volumetric production rate of 12.7 L m- 2 d- 1 . The gradual increase of the voltage to 1.0 V and 1.2 V led to the increase of current production up to density of ca. 2.7 and 4.5 A m- 2 , respectively. However, hydrogen production was unstable due to the concomitant use of electrons and/or hydrogen by possible synthesis reactions. The identification of Thermoanaerobacterium and Caproidiproducens as the main microorganisms during the operation suggested the establishment of a co-culture in which hydrogen entered a loop of production and consumption in the single-chambered MEC.

This study evaluated the anaerobic digestion of the liquid fraction of fruit and vegetable waste to optimize energy recovery through sequential hydrogen and methane production. Two configurations were tested: a single-stage (SS) system using an upflow anaerobic sludge blanket (UASB) reactor and a two-stage (TS) system combining an anaerobic structured bed reactor (AnStBR) with a UASB reactor. The objective was to identify the most efficient configuration under various organic loading rates (OLR). In the AnStBR, OLR ranged from 40 to 80 g COD/Lreactor·day, while in UASB reactors, the OLR range was from 1.5 to 22.0 g COD/Lreactor·day. The TS outperformed the SS in methane production, achieving 3.6 NL CH4/Lreactor·day at an OLR of 22.0 g of COD/Lreactor·day. It also demonstrated a higher energy potential, generating a total of 1554.9 KJ/day35.7% more efficient than the SS. Additionally, the UASB-TS reactor maintained stability throughout the study, with minimal acid accumulation and an intermediate alkalinity/partial alkalinity ratio (IA:PA) consistently below 0.4, even at elevated OLR. In contrast, the UASB-SS reactor showed signs of acidification at higher OLR. These findings suggest that TS anaerobic digestion offers a more robust and efficient solution for treating high-strength organic waste, enhancing both energy recovery and process stability.

Sugarcane vinasse, a byproduct of ethanol production, presents environmental challenges due to its high organic content and occasional contamination with antibiotics, such as monensin. This study successfully evaluated thermophilic two-phase anaerobic digestion for simultaneous monensin degradation and biogas production. The system, consisting of an acidogenic anaerobic structured-bed bioreactor (ASTBR) operating at with a hydraulic retention time (HRT) of 7.5 h followed by a methanogenic reactor at HRT = 24 h, with two options of the methanogenic phase, an upflow anaerobic sludge blanket (UASB), and an ASTBR, operated continuously for 254 days with incremental monensin concentrations (0–2000 ng·mL−1). The acidogenic reactor consistently removed over 70% of monensin across all phases, demonstrating its effectiveness as a pretreatment step. At realistic residual concentrations (20–100 ng·mL−1), monensin not only failed to inhibit biogas production but enhanced methane yield by up to 100% through selective pressure on the microbial community. This study demonstrated that anaerobic digestion can effectively degrade monensin while increasing the value of vinasse, providing a scalable solution for mitigating antibiotic contamination and enhancing bioenergy recovery in the sugarcane–ethanol industry.

Lignocellulosic residues are promising substrates for bioenergy production, but lignin recalcitrance hinders their anaerobic conversion. This study investigated lignin degradation under sulfate-reducing conditions using olive stones as a model substrate (lignin content of 59.9 ± 3.9 %). Eight batch reactors evaluated the effects of cellulose co-substrate, sulfate (1  g L-1), nutrients, and excess metals (Fe 50  mg L-1, Zn 5  mg L-1, Cu 5  mg L-1). The most effective configuration (olive stones, cellulose, sulfate, nutrients, excess metals, inoculum) reached 30 % lignin degradation and the highest organic matter conversion (1041  mg O2), outperforming setups lacking sulfate or nutrients. Compared to cellulose-only systems, adding the lignocellulosic residue increased methanogenesis by 19 % and sulfidogenesis by 35 %, demonstrating that sulfate, nutrients, and excess metals enabled effective lignocellulosic use by the anaerobic consortium. With sulfate and without excess metals, lignin removal was 20 %. Inoculated systems without sulfate or without sulfate and co-substrate showed lignin degradation below 15 %. Notably, systems without inoculum but with nutrients reached similar lignin removal (up to 15 %), confirming the relevance of autochthonous microbiota when nutrients are available. Overall, the results show that sulfate reduction, combined with nutrient and metal inputs, can overcome lignin recalcitrance in anaerobic conditions. The approach offers potential for integrated biorefinery systems, enabling co-treatment of crop waste and mining-influenced water, while contributing to circular bioeconomy goals through waste valorization and environmental remediation.

Modeling the anaerobic digestion of wastewater containing sulfate is important for understanding and optimizing the process, enabling the prediction of operational conditions in reactors to maximize sulfate removal. The goal of this work was to develop an extension of the Anaerobic Digestion Model No. 1 (ADM1) for the sulfate reduction process using ethanol as an electron donor and source of organic matter. A pilot-scale anaerobic sequencing batch biofilm reactor (ASBBR) was operated with a chemical oxygen demand (COD)/sulfate ratio (M/M) close to 2.0, using industrial wastewater with an initial sulfate concentration of 1.45 g L-1 for model calibration and 2.30 g L-1 for validation. The free parameters values, which are the initial biomass concentrations in the reactor, were determined using the Box-Draper minimization method and Markov-chain Monte Carlo (MCMC) simulation until convergence was obtained, assisted by the Geweke test. In both the calibration and simple validation, the model fitted properly the experimental data for ethanol and sulfate consumption, as well as the production and consumption of acetic acid by the microorganisms. Concerning COD, the simulated results differed slightly from real values, mainly during calibration. The sum of the average biomass concentrations (Xac0, XaSRB0, Xeth0, XethSRB0, Xh20, and XhSRB0) obtained by model closely matched the value measured. Statistical analysis supports the validity and robustness of the model in representing the experimental data.

The rising demand for renewable energy and sustainable waste management has encouraged interest in biohydrogen (bioH2) as a clean energy source. This study aimed to assess the potential of microalgae-bacteria consortia biomass (MBCB) as an inoculum for bioH2 production. MBCB, cultivated in high-rate algal ponds (HRAPs) treating domestic wastewater, was used to produce bioH2. Natural fermentation (NF) was applied to both raw (RB) and thermally pretreated biomass (PB) for 5, 10, and 15 days to optimize microbial selection. Biohydrogen production potential (BHP) and microbial dynamics were evaluated. Thermal pretreatment enhanced bioH2 yield but prolonged the lag phase and lowered production rates. RB fermented for 5 days (RB-5) achieved the highest bioH2 production rate (1.25 +/- 0.08 mmol H2 h- 1). Microbial analysis revealed higher diversity in RB than PB, with PB selecting thermoresistant microorganisms like Clostridia. NF promoted shifts in microbial communities, favoring fermentative bacteria. These findings underscore the promise of using MBCB as inoculum for bioH2 production and demonstrate the viability of integrating NF and MBCB for renewable energy generation from wastewater biomass. However, additional economic and environmental evaluations are required to confirm feasibility at larger scales.

Global scientific literature has extensively documented the overuse of antibiotics, the proliferation of antibiotic-resistant bacteria, and the toxic effects on aquatic fauna from hospital wastewater exposure, highlighting the need for effective antibiotics treatment methodologies. Anaerobic biodegradation has been recognized as an effective method for removing antibiotics and other pharmaceuticals from hospital wastewater, demonstrating the ability to degrade various antibiotic classes. This review critically examines the environmental fate of the antibiotics classes fluoroquinolones, sulfonamides, and diaminopyrimidines in hospital wastewater, emphasizing anaerobic biodegradation as an effective technology and the significance of the microbial community in this process. Furthermore, it examines ecotoxicological impacts across diverse species. The inappropriate disposal of inadequately treated hospital effluent into the environment disseminates antibiotics into freshwater, resulting in sublethal effects on aquatic fauna. The current research gap underscores the promise of anaerobic technologies, coupled with the toxicity assessment of treated effluents containing antibiotic mixtures, to improve comprehension of the environmental fate and effects of these antibiotic classes on aquatic vertebrate and invertebrate species.