[object Object], [object Object], [object Object] et al.

Materials • 2026

To address the dual challenges of aqueous phosphate pollution and the resource utilization of petrochemical solid wastes, this study proposes a novel closed-loop “waste-to-waste” strategy. This approach innovatively integrates multiple solid wastes (including oily sludge and petroleum hydrocarbon-contaminated soil) into a porous ceramic matrix and utilizes lanthanum recovered from spent catalysts for surface modification, successfully fabricating an optimized adsorbent—lanthanum-modified ceramsite (BC@La). Under the conditions of pH 6, an adsorbent dosage of 1 g/L, and a temperature of 318 K, BC@La achieved a maximum phosphate adsorption capacity of 2.56 mg/g, corresponding to 128.0 mg of phosphorus per gram of La. Kinetic and isotherm analyses revealed that the adsorption process followed the pseudo-second-order model and fitted well with the Langmuir isotherm, consistent with monolayer chemisorption. Thermodynamic studies further indicated that the adsorption was spontaneous and endothermic. The primary adsorption mechanism was attributed to the precipitation of lanthanum phosphate (LaPO4). This study not only demonstrates a high-performance adsorbent but also provides a sustainable strategy for the synergistic utilization of industrial solid wastes.

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Polymers • 2026

This study investigates the potential of pure chitosan powder as an effective, sustainable, and low-cost adsorbent for the removal of synthetic dyes from aqueous media. The work demonstrates the potential of pristine chitosan for practical wastewater treatment applications by adsorbing two commonly used textile dyes, methyl orange (MO) and methylene blue (MB). To elucidate the adsorption mechanism, chitosan was comprehensively characterized using zeta potential analysis, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM–EDX), Thermogravimetric Analysis (TGA), Brunauer–Emmett–Teller (BET) surface area analysis, and point of zero charge (pHpzc) determination. FTIR analysis revealed notable shifts in –NH2 and –OH functional groups after dye adsorption, confirming their involvement in electrostatic interactions and hydrogen bonding with MO and MB. SEM images demonstrated significant surface morphological changes following adsorption, while EDX spectra confirmed successful dye uptake through the appearance of sulfur and nitrogen signals characteristic of MO and MB, respectively. Zeta potential and pHpzc results explained the strong pH-dependent adsorption behavior, highlighting favorable electrostatic attraction between chitosan and the ionic dyes. The optimum adsorption conditions were achieved at adsorbent dosages of 0.5 g for MO and 1.0 g for MB, a contact time of 30 min, initial dye concentrations of 20 and 100 mg/L, and solution pH values of 3 for MO and 9 for MB at room temperature. The adsorption data fit the Langmuir isotherm model, indicating monolayer adsorption on a homogeneous chitosan surface, with maximum adsorption capacities of 7.843 mg/g for MO and 7.605 mg/g for MB. Kinetic studies showed that adsorption followed the pseudo-second-order model, suggesting chemisorption as the dominant mechanism. Thermodynamic analysis indicated that the adsorption process was endothermic and non-spontaneous under the investigated conditions. In conclusion, these findings demonstrate that unmodified chitosan is a practical, eco-friendly adsorbent for dye removal, achieving removal efficiencies comparable to many modified chitosan composites, and represents a promising candidate for sustainable wastewater treatment.

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Research Square • 2026

Abstract Introduction Orthodontic fixed retainers are often a predilection site for calculus build-up. However, standardized protocol for professional mechanical plaque removal (PMPR) does not yet exist that takes into account the slight weakening of the adhesive bond. Material and Methods In this in-vitro study, three cleaning protocols were evaluated: Group A: ultrasonic stainless-steel tip (Piezon PS, EMS Dental); Group B: Polyetheretherketone (PEEK) ultrasonic tip (PI Max, EMS Dental); and Group C: sonic cleaning (SiroTip S1, Sirona Dental Systems). These protocols were assigned artificial lower canine-to-canine segments with individual Twistflex retainers bonded (n = 10/group). Following artificial ageing of the adhesive bond, artificial calculus was applied and removed according to the respective cleaning protocol. After repeating twice, adhesive bond strengths were analysed. Results The Kruskal-Wallis test showed that the choice of instrumentation significantly influences the integrity of the adhesive bond (p = 0.036). Post-hoc pairwise comparisons revealed that Group A had significantly higher shear bond strength compared to Group C (p = 0.028). Conclusions This in-vitro study shows that the type of the PMPR system used has a significant influence on the shear bond strength of fixed retainers. Ultrasound-driven stainless-steel scalers appear to be more gentle than sonic-driven devices. Clinical relevance In clinical practice, the accidental debonding of retainer attachments during PMBR is a frequent complication. The present in-vitro study investigates whether specific cleaning modalities can minimize the risk of compromising the adhesive bonding. Specifically, different cleaning modalities (ultrasonic versus sonic) and various tip materials are evaluated and compared.

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Materials • 2026

Diamond coatings with three distinct surface textures, namely spherical, pyramidal, and prismatic morphologies, were fabricated using the hot-filament chemical-vapor deposition (HFCVD) method. Scanning electron microscopy (SEM) was employed to analyze the surface morphological characteristics and differences among the coatings. Raman spectroscopic analysis further confirmed that all three diamond films exhibited excellent deposition uniformity and high crystalline quality. A three-dimensional optical microscopy system was used to measure the surface roughness values, which were determined to be Ra 0.423 μm, Ra 0.515 μm, and Ra 0.809 μm, respectively. An HFCVD diamond-coated tool was innovatively employed for the lapping of sapphire wafers, enabling a systematic investigation of the tribological behavior during the lapping process. Based on the experimental results, three morphological material removal models were established. The study demonstrates that the spherical diamond coating achieves a superior surface finish (Ra 0.22 μm) due to its continuous multi-point contact geometry, governed by the agglomerated nanocrystalline structure. Sample 3 had the highest removal rate of 24.3 μm/min. This is related to its surface morphology characteristics and is also due to the two-body contact between the diamond-coated tool and sapphire, offering a high-efficiency alternative for precision machining.

Data in brief • 2026

This data article describes a comprehensive dataset investigating the dynamics between microalgae, bacteria, and pollutant removal in dairy wastewater treatment. Data was collected from a 12-day laboratory-scale experiment employing three distinct cultivation systems: monoculture, co-culture, and sequential culture of four algal/cyanobacterial strains ( Chlorella sorokiniana, Euglena gracilis, Synechocystis sp., and Desertifilum tharense ). The generated dataset includes high-frequency measurements of water quality parameters (COD, NH 4 + -N, TN, TP), algal physiological data (biomass production, total chlorophyll, biochemical compositions like proteins, lipids, and polysaccharides), and 16S rRNA gene sequencing data of the associated bacterial communities, which were fractionated into free-living and tightly bound phycosphere populations. The reuse potential of this data is significant. It provides a detailed profile of microbial community assembly driven by different cultivation strategies and environmental factors, offering a benchmark for future ecological studies in engineered systems. Researchers in the fields of wastewater biotechnology, microbial ecology, and synthetic ecology can reuse this data to validate microbial interaction models, optimize consortia design for bioremediation, and inform life-cycle assessments of algal-based treatment processes. The dataset generated in this study is publicly available in the NCBI BioProject repository under the accession number [PRJNA1265442].

Journal of hazardous materials • 2026

High-salinity nitrogenous organic industrial wastewater poses a severe threat to microbial activity due to its extreme osmolarity and complex composition, often causing catastrophic failure of biological nitrogen removal systems. This study presents a novel strategy employing AHL-based quorum sensing to systematically mitigate salinity inhibition, achieving dual enhancement of complex organic nitrogen mineralization and inorganic nitrogen removal. The AHL 3-oxo-C6-HSL was identified as the most effective compound, promoting ammonia oxidation and minimizing nitrite accumulation under salinity stress. In SBR systems, 3-oxo-C6-HSL accelerated the completion of nitrification under 5 % salinity within 5 days, compared to 18 days in the control, and achieved a TN removal rate of 79.46 % under 8 % salinity, which was significantly higher than that of other AHLs. In the biological aerated filter, the addition of 3-oxo-C6-HSL enabled the system to maintain high stability and efficiency even at 8 % salinity. This enhancement was evidenced by a 37.87 % reduction in nitrite accumulation compared to the control, 99 % aniline degradation within 5 days, and the concurrent removal of 95 % COD and 80 % TN under saline conditions. Mechanistic analysis revealed that 3-oxo-C6-HSL activated microbial quorum sensing, thereby enhancing metabolic activity and salinity-tolerant defense mechanisms. Additionally, it facilitated the formation of a denser and more stable biofilm structure. Omics analysis further revealed that AHLs significantly enriched key aniline degraders, such as Azoarcus, systematically activating multiple rate-limiting enzymes within both the aniline degradation pathway and the inorganic nitrogen conversion cycle. This research presents an innovative and efficient microbial communication strategy for the biotreatment of high-salinity, nitrogenous organic wastewater, thereby expanding the understanding of biological nitrogen removal under extreme environmental stress.

Bioresource technology • 2026

Enhancing methane production (MP) in anaerobic digestion (AD) systems largely relies on improving electron transfer between bacteria and methanogens, yet conductive materials' acceleration effects and stability pose challenges for practical use. This study constructed continuous-flow reactors to evaluate conductive material sustainability by analyzing reactor performance and sludge characteristics under different organic loading rates (OLR), with stable mechanisms elucidated via enzyme activity, microbial community, and functional gene variation. Results revealed that the SH-mediated reactor (R SH ) achieved the highest COD removal (97.0% ± 1.8%) and methane production (6.7 ± 0.2 L/d) at a high OLR of 48.7 ± 1.2 kg/(m 3 ·d) by enriching Desulfomicrobium (19.5%) and Methanothrix (54.4%), promoting acetoclastic methanogenesis (AM) via conductive-pili gene expression. However, under ultra-high OLR, R SH became unstable due to sludge washout caused by excessive extracellular polymeric substance (EPS) secretion (184.3 ± 22.1 mg/L), which further inhibited MP activity of remaining microbes. In contrast, the PAC-mediated reactor (R PAC ) maintained stability under ultra-high OLR by leveraging PAC's inherent conductive properties and upregulating cytochrome-C and flavin-protein genes, facilitating direct interspecies electron transfer (DIET) between Clostridium (64.9%) and hydrogenotrophic methanogenesis (HM) archaea (60.5%). Both SH and PAC enhanced the performance of AD reactors; nonetheless, R SH exhibited limited OLR stress resilience due to its enhanced AD pathway having excessive metabolic activity, whereas R PAC demonstrated robust performance through the reinforced syntrophic propionate oxidation (SPO)-HM pathway. This study highlighted the balance between the strengthening effect of conductive materials and sustainability in AD optimization, which advanced understanding of conductive material applicability, offering practical insights for sustainable anaerobic digestion technologies.

Environmental pollution (Barking, Essex : 1987) • 2026

Co-occurring micro(nano)plastics (MNPs) and heavy metals (HMs) may interact synergistically or antagonistically with microorganisms, thereby influencing wastewater treatment performance. Constructed wetlands (CWs) inoculated with functional microbes such as arbuscular mycorrhizal fungi (AMF) offer a promising approach to enhance pollutant removal. Here, we established CWs with and without AMF inoculation to examine how varying concentrations (1 and 10 mg/L) of polystyrene MNPs (PS-MNPs) affect nutrient removal and greenhouse gas (GHG) production in wastewater co-contaminated with copper/lead. Our results show that in CWs without AMF inoculation, compared with single HMs, the addition of PS-MNPs increased the average effluent concentration of ammonium nitrogen and phosphate by 11.84-134.73 % and 2.04-109.79 %, respectively, while their effects on nitrate and COD removal depended on concentration and HM levels. Inoculation with AMF reduced average effluent concentration of ammonium nitrogen and phosphate by 22.01-69.24 % and 21.89-50.47 %, respectively, and also produced a significant decrease in nitrate concentration. PS-MNPs suppressed organic matter and nitrogen transformations, leading to methane (CH 4 ) And nitrous oxide (N 2 O) production elevated 2.18-53.78 % and 24.19-162.23 %, whereas AMF reduced their production. Enzyme assays indicated that PS-MNPs decreased key microbial activities in the upper layer, but AMF mitigated these impacts. Microbial community analysis revealed that AMF enhanced nitrogen cycling by promoting denitrifying bacteria (e.g., Dechloromonas, Zoogloea, Terrimonas, Thauera) and nitrifiers (Nitrospira). These findings highlight that AMF can alleviate the negative impacts of MNPs-HM co-occurrence on CWs, improving both nutrient removal and climate co-benefits. This work provides insights into pollutant interactions and offers strategies for optimizing CWs treating complex wastewater mixtures.

Water research • 2026

The environmental dissemination of antibiotic resistance genes (ARGs) is a cornerstone of the One Health crisis, linking human, animal, and environmental health. Engineered ecosystems, such as constructed wetlands (CWs), are critical for water purification, but the design of their core reactive media has focused on pollutant removal, overlooking potential ecological risks. This study reveals a fundamental performance-risk trade-off by comparing four biogeochemically distinct substrates (river sand, zeolite, biochar, pyrite) in CWs treating multi-antibiotic wastewater. While biochar-amended CWs excelled at removing COD (95.2 ± 2.1%) and parent antibiotics (>90%), they simultaneously evolved into hotspots for antibiotic resistance, elevating the horizontal transfer potential (intI1 gene) by approximately 340-fold and enriching for multiple ARGs compared with control. Furthermore, biochar steered antibiotic degradation towards transformation products with a predicted potential for significantly higher ecotoxicity towards Daphnia. In contrast, pyrite-amended CWs demonstrated a paradigm of safe efficiency: despite exhibiting comparable high removal rates for organic matter and antibiotics, they simultaneously suppressed ARG proliferation via a biogeochemical stress mechanism driven by iron-sulfur cycling and elevated reactive oxygen species (ROS) production and minimized nitrous oxide (N 2 O) emissions by 78% relative to the control. Machine learning and structural equation modeling identified distinct microbial functional guilds as the causal drivers of these divergent risks. Our findings demonstrate that prioritizing removal efficiency alone is a flawed strategy. Pyrite emerges as a superior functional substrate that optimally balances high performance with low ecological risk, providing a sustainable, One Health-aligned engineering solution for the design of next-generation, environmentally safe treatment bioreactors.

Bioresource technology • 2026

Pig manure management is an environmental challenge that can be improved through high-rate anaerobic digestion, enabling efficient biogas production and resource recovery. This study evaluated a pilot-scale two-stage expanded granular sludge bed (EGSB) system treating real pig slurry over a 150-day start-up. The reactors, operated in series with different working volumes (100 and 500 L), underwent progressive hydraulic retention times (HRT) reductions (R1: 3-1 d; R2: 12-7 d), increasing organic loading rates (OLR) (R1: 7.6-21.4 kg COD m -3 d -1 ; R2: 1.0-2.5 kg COD m -3 d -1 ). General chemical oxygen demand (COD) removal reached 68%, with system sensitivity to high solids, while biogas production and methane yield (MY) remained stable, reaching 264 L/d and 352 L CH 4 /kg COD removed. Microbial analysis identified Clostridium sensu stricto_1, Methanosarcina, and Methanoculleus as key taxa supporting process stability. These results demonstrate the potential of two-stage EGSB systems for sustainable pig manure valorisation.

Bioresource technology • 2026

The stability of anaerobic granular sludge (AnGS) is frequently compromised by the biotoxicity of recalcitrant organic compounds. The present study employed exogenous signalling molecules (AHLs) and nanoscale Fe 3 O 4 (Fe 3 O 4 NP) particles to modulate quorum sensing (QS) and direct interspecies electron transfer (DIET). The findings of the study demonstrated that this combined strategy enhanced COD removal by 22.4% and increased methane yield by 54.4%. The results of this study demonstrate that AHLs and Fe 3 O 4 NPs induce granular structural remodelling, promote secretion of hydrophobic extracellular polymers, and enrich methanogenic and mutualistic microbial communities. QS and DIET synergistically upregulated genes such as pilA/B and fpo, enhancing c-Cyts and conductive pili assembly to establish efficient electron transfer pathways. Concurrently, they stimulated the synthesis of hydrophobic amino acids, thereby strengthening the stability of biofilms. This study constitutes the inaugural demonstration of synergistic QS and DIET regulation, thereby establishing a theoretical framework for enhancing AnGS performance in the treatment of refractory organic wastewater.

Bioresource technology • 2026

This study evaluated four microalgae-based technologies for nutrient (total nitrogen, TN; total phosphorus, TP; chemical oxygen demand, COD) and six antibiotic removal from swine wastewater across four breeding periods. Using Chlorella pyrenoidosa (C. pyrenoidosa), Bacillus cereus (B. cereus), and Rhizopus oryzae (R. oryzae), we established monoculture, binary co-cultures, and tripartite co-culture (Treatment 4). Treatment 4 outperformed the other treatments in the late fattening stage and non-pregnant sow stage, achieving TN removal of 89.67 ± 5.45%, TP removal of 87.58 ± 6.64%, COD removal of 92.58 ± 4.71%, and antibiotic removal of 88.54-96.35% (P < 0.05). Adding 5-deoxystrigol (5-DS) at 10 -6 M maximized the efficiency, increasing the TN, TP, COD, and Oxytetracycline (OTC) removal efficiencies by 3.81-4.67% compared to those of the control (P < 0.05). This system provides a standardized solution for intensive treatment of swine wastewater.

Bioresource technology • 2026

This study compared the treatment of high-salinity pharmaceutical wastewater by using Continuous Stirred Tank Reactor (CSTR), Upflow Anaerobic Sludge Blanket (UASB), and two-phase Cascade Energy Anaerobic Reactor (CEAR) with bioaugmentation (Bacillus altitudinis K3). The CEAR significantly increased methane production through separating acidogenic and methanogenic phases, achieving a 9.70% to 23.10% higher methane content than other systems. With the increase in salinity and organic loading rate, the chemical oxygen demand (COD) removal efficiency of CSTR decreased significantly. In contrast, both the UASB and CEAR reactors maintained a high COD removal rate above 85%. Bioaugmentation can alleviate salt inhibition, enhanced microbial activity, and enriched salt-tolerant methanogens. The CEAR combined with bioaugmentation offered an effective strategy for methane recovery from high-salinity pharmaceutical wastewater.

Bioresource technology • 2026

The valorization of nutrient-rich food-processing wastewater through single-cell protein (SCP) production offers a sustainable route to simultaneously reduce pollution and supplement protein supplies. However, the frequent nitrogen deficiency in such wastewater limits efficient microbial protein synthesis. This study demonstrates the pilot-scale production of SCP from real soybean-soaking water (SSW) using ammonium sulfate recovered from chicken manure as a sustainable nitrogen supplement. Without supplementation, the nitrogen-limited SSW yielded only 0.18 ± 0.03 grams SCP per gram chemical oxygen demand removed (COD R ) with a crude protein content of 42.0 ± 1.0%. Adding recovered nitrogen at a carbon‑to‑nitrogen ratio of 33 significantly improved performance, raising SCP yield to 0.34 ± 0.04 g/g COD R and protein content to 47.7 ± 1.0%. However, excessive nitrogen addition led to sulfides accumulation and the precipitation of potentially toxic elements in SCP. This integrated approach effectively couples wastewater treatment with the production of high-value SCP, advancing a circular bioeconomy in the food industry.

Bioresource technology • 2026

Seafood processing wastewater presents a significant treatment challenge due to its high salinity, elevated organic load, and substantial lipid-protein content. This study evaluated a pilot-scale hybrid Anaerobic Membrane Bioreactor-Intermittent Cycle Extended Aeration System (AnMBR-ICEAS) operated onsite with real seafood wastewater to achieve simultaneous organic removal, nutrient reduction, and energy recovery. The AnMBR achieved stable COD removal of 75.2-87.6 % with methane yields of 132-289 mL CH 4 /g COD_removed (average 220 ± 50 ml/g), supported by a robust fermentative-syntrophic microbial consortium despite moderate membrane fouling. Nutrient removal in the AnMBR remained limited (TN: 6.4-17.6 %; TP: 10-20 %). The ICEAS maintained active biomass (∼3,500 mg/l) and achieved high removals of COD (89-92 %), TN (77-91 %), and TP (11-38 %), with phosphorus removal strongly governed by hydraulic retention time. Microbial analysis revealed the dominance of Pseudomonadota, Betaproteobacteria, Alphaproteobacteria, and Planctomycetota, supporting efficient heterotrophic degradation and synergistic nitrogen removal via nitrification-denitrification and anammox-related pathways. When integrated, the hybrid AnMBR-ICEAS system achieved up to 98.7 % COD, 96 % TN, and 47 % TP removal, demonstrating synergistic performance and operational robustness. These results highlight the AnMBR-ICEAS configuration as a compact, energy-efficient, and sustainable treatment strategy for high-strength saline seafood wastewater.

Scientific reports • 2026

The online version contains supplementary material available at 10.1038/s41598-026-37758-7.

Water research • 2026

Efficient total nitrogen (TN) removal from low-carbon wastewater remains challenging due to electron donor scarcity, often causing incomplete denitrification and nitrite accumulation. To address this, an in-situ sulfur-enhanced anoxic/oxic (HS 0 AD-A/O) system was established, enabling S 0 -driven electron redistribution for enhanced TN removal without additional carbon input or process restructuring. Under decreasing influent C/N ratios (4 to 2), HS 0 AD-A/O outperformed conventional HD-A/O by 32.76-111.16% of TN removal efficiency. Electron balance showed S 0 oxidation contributed 9.21-27.59% of total electron flux, compensating for carbon deficiency. Increasing the S 0 implantation ratio to 28% shifted the dominant pathway toward S 0 -based autotrophic denitrification, where S 0 -derived electrons surpassed those from COD (58.27% vs. 41.73%). Kinetic assays revealed that S 0 -driven denitrification preferentially reduced NO 2 ⁻ over NO 3 ⁻, thereby minimizing NO 2 ⁻ accumulation and yielding a distinct S 0 ‑saving effect (1.14-1.57 g-S 0 /g-N here). Microbial and transcriptional analyses further elucidated a synergistic division of labor: heterotrophic denitrifiers (e.g., Hydrogenophaga, Rhodocyclaceae) in sludge primarily reduced NO 3 ⁻-N but tended to cause partial denitrification, whereas S 0 -attached autotrophs (e.g., Thiobacillus, up to 46.10% in biofilms) specialize in complete denitrification and efficiently converted NO 2 ⁻-N to N 2 , accompanied by marked upregulation of nirKS and nosZ genes. Overall, in-situ S 0 implantation restructured electron transfer networks, enabling stable, efficient, and dual-saving (carbon and S 0 ) TN removal while providing mechanistic insight for scalable applications.

Bioresource technology • 2026

Artificial rumen systems promise for converting lignocellulosic biomass into renewable products but face challenges in long-term operation. This study developed a novel artificial rumen system combined fermentation with acid absorption using methanogenic granules and a dynamic membrane. Over 480 days, volatile fatty acids (VFAs) were effectively separated by the dynamic membrane and immediately absorbed by granules, simulating natural ruminant acid absorption. Despite increasing the organic loading rate from 3.27 to 8.18 g-VS/L/day, stable VFA yields of 0.21-0.24 g-COD/g-VS were maintained. After 440 days, removal efficiencies for cellulose, hemicellulose, and lignin reached 62.7 %, 52.1 %, and 40.7 %, respectively. The acid absorption unit efficiently converted VFAs into biomethane (302-304 mL/g COD), showing high bioenergy potential. Metagenomic analysis confirmed key rumen microbes (Firmicutes, Bacteroidetes) were dominant, with enrichment of low-abundance species like Prevotella and Solobacterium that secreted lignocellulose-degrading enzymes. The system enables long-term biomass conversion and supports future high-load artificial rumen engineering.

Bioresource technology • 2026

This study investigated the effectiveness of treating concentrated municipal wastewater using the forward osmosis (FO) process in an anaerobic dynamic membrane bioreactor (AnDMBR) over a 180-day period. The pre-concentration factor of the FO process was gradually increased from 1 to 2 and 3.33, leading to stepwise increases in the organic loading rate (from 0.17 to 0.71 kg COD/m 3 .d) and salinity accumulation (from 1.30 to 3.30‰) in the AnDMBR, while high chemical oxygen demand (COD) removal efficiencies (>90%) and overall digestion stability were generally maintained. Subsequently, three different sludge retention times (SRTs) were applied in continuous operation at 3.33 pre-concentration factor-20, 40, and 60 days-to evaluate the changes in sludge characteristics and filtration performance of the dynamic membrane (DM). Lower filtration resistance was observed at an SRT of 20 days, potentially due to enhanced flocculation associated with higher bulk EPS concentrations and reduced soluble microbial product accumulation in the reactor. Morphological analysis of the DM revealed the presence of inorganic elements, particularly divalent cations, as well as organic substances, including proteins and polysaccharides. Bacterial community analyses of anaerobic sludge showed that the phyla Chloroflexota, Bacteroidota, Patescibacteria, and Bacillota were the most resilient and adaptable under varying stress conditions. Finally, the energy balance assessment indicated that a net positive energy balance could be achieved, with energy recovery exceeding 2.41 kWh/m 3 at an FO pre-concentration factor of 3.33.

Bioresource technology • 2026

A mixed culture, prepared by acclimatising Chlorella vulgaris (C. vulgaris) to municipal wastewater (MWW), was used in two reactors: one was inoculated with activated sludge (AS), and the other was not (NAS). Under 12:12 h light: dark, mixing, and a hydraulic retention time of 1.17 d, both systems removed ∼92 % of 270 mg-COD/L, 57 % of 70 mg-N/L, and 27 % of PO 4 3- -P, while achieving a sludge volume index of 42 mL/g. C. vulgaris disappeared and was replaced by other algae, including cyanobacteria, indicating that inoculation is not necessary. Higher dissolved oxygen production, IC uptake, and nitrification occurred in the NAS reactor than in the AS reactor, supported by a higher abundance of the autotrophic/aerobic community in the NAS reactor. Genomic data revealed latent mechanisms (denitrification, N-fixation, nitrate/nitrite reduction, multiple phosphorus pathways) than mass balance. Pure algae seeding is not essential, but activated sludge seeding could affect performance.

Water environment research : a research publication of the Water Environment Federation • 2026

Water resource recovery facilities often receive landfill leachate (LL), which can disrupt biological processes due to its toxicity and low biodegradability. This study evaluates the anaerobic codigestion (AcoD) of municipal wastewater (MWW), LL, and crude glycerin (CG) as a strategy to enhance organic matter removal and methane yield. Batch reactors were operated under varying conditions defined by a Plackett-Burman screening design, and methane production kinetics were modeled using modified Gompertz and Cone equations. Soluble chemical oxygen demand (sCOD) removal ranged from 67.4% to 94.3%, whereas methane yield varied between 0.076 and 0.349 L NCH4 /g tCOD add (liters of normalized methane per gram of total COD added). The highest yield was achieved with 2% LL and 1% CG, approaching the theoretical maximum. Statistical analysis revealed that increasing CG content reduced methane yield, and extending the digestion time to 40 days offered limited performance gains. Despite the presence of inhibitory compounds, most conditions showed stable digestion, with short latency phases and effective microbial adaptation. These findings demonstrate the feasibility of codigesting MWW, LL, and CG, especially under optimized proportions, and highlight the potential for energy recovery in wastewater treatment plants using biodiesel by-products.

Environmental technology • 2026

The purpose of this study was to investigate the effects of COD interference on biological nutrient removal, granule characteristics, and microbial community dynamics in continuous-flow Simultaneous Nitrification, Denitrification, and phosphorus Removal (SNDPR) granular sludge under low aeration energy consumption conditions. The experiment employed an innovative Automatic Internal Circulation Continuous Flow Reactor (AIC-CFR) at an aeration rate of 0.8 L/min, maintaining the dissolved oxygen level below 0.5 mg/L, and the COD concentration increased from 300 to 500 mg/L in steps of 100 mg/L. The results demonstrated that increasing the COD concentration to 400 mg/L significantly enhanced the removal efficiencies of total phosphorus and total nitrogen, while simultaneously optimizing the settling properties of the granules. However, when the COD concentration reached 500 mg/L, the settling ability and stability of the granules deteriorated. As the COD concentration increased, the population of the filamentous archaea Methanothrix significantly increased, whereas the abundance of the filamentous bacteria Thiothrix gradually decreased. The abundance of these filamentous microorganisms was closely correlated with the sludge volume index, granular integrity coefficient, and extracellular polymeric substances. High-throughput sequencing results revealed that DPAOs-Pseudomonas have consistently been the absolute dominant genus in the system. It is AOA rather than AOB that undertakes the task of oxidizing ammonia nitrogen to nitrous nitrogen. Finally, a granular ecological conceptual model is proposed to elucidate the underlying mechanisms of the AIC-CFR system. This study elucidated the stability mechanism of SNDPR granules, providing technical support for the low-carbon engineering operation of granular sludge.

Bioprocess and biosystems engineering • 2026

Low influent carbon-to-nitrogen (C/N) ratios often limit denitrification in municipal wastewater treatment systems. This study evaluated denitrification performance in a full-scale anaerobic-anoxic-oxic (AAO) process equipped with a 6 m-deep anoxic tank containing spherical fixed carriers. Sludge flocs and carrier-attached biofilms were sampled at depths of 1 m, 3 m and 5 m along the horizontal flow path. Denitrification kinetics were quantified using batch tests, and microbial community structures were analyzed by 16 S rRNA gene sequencing. Sludge flocs exhibited the highest denitrification rates at 1 m, whereas biofilms performed optimally at 3 m. Along the horizontal direction, sludge flocs near the influent and external carbon dosing site showed enhanced denitrification, while biofilms downstream of the propeller demonstrated improved denitrification. Elevated dissolved oxygen (DO) introduced by internal reflow reduced the effective utilization of the external carbon source. Nitrosomonas was more abundant in sludge flocs, whereas Thauera dominated denitrifying community and peaked at 3 m in biofilms. Based on the spatial distribution of denitrification kinetics and microbial communities, the conventional "pre and top" carbon dosing strategy was re-evaluated, and an optimized "post and top" dosing strategy was proposed. This strategy reduced chemical oxygen demand (COD) consumption per unit of total nitrogen (TN) removed by 16%, providing a practical approach to enhance denitrification efficiency and external carbon utilization in full-scale anoxic tanks.

Environmental research • 2026

Algal-bacterial granular sludge (ABGS) has unique advantages and broad application prospects in the treatment of mariculture wastewater. However, the rapid granulation process and performance evolution of ABGS under high salt stress have not been clearly defined. Compared with AGS, the influence of algal intervention on the structural integrity and metabolic activity of particles under the same salinity gradient is also unknown. Therefore, in this study, a parallel ABGS and AGS system was established. The results showed that intertwined algal filaments provided a structural skeleton for particle formation and led to complete granulation of ABGS within 20 days. Compared with conventional AGS, ABGS formed under high-salinity conditions exhibited a larger average particle size (1.07 mm), higher biomass (7.59 g/L) and higher extracellular polymeric substance (EPS) secretion (258.56 mg/g VSS). Additionally, chemical oxygen demand (COD) and total inorganic nitrogen (TIN) removal efficiencies exceeded 99% and 66%, respectively. Metagenomic analysis revealed that Thauera, Fragilaria and Nitzschia were dominant taxa associated with granule formation and stabilization. ABGS also showed an elevated abundance of functional genes associated with nitrogen metabolism (nxrA, nasA, and nasD) and polysaccharide metabolism (glmM, glmU, and pmm-pgm), which were in accordance with the enhanced nitrogen removal and granulation capability. Increased abundance of tricarboxylic acid cycle genes further indicated the superior granulation performance of ABGS. Overall, this study clarifies the morphological evolution and microbial functional mechanisms underlying rapid ABGS formation in mariculture wastewater, offering valuable insights for engineering optimisation and application of this technology in saline wastewater treatment.

Scientific reports • 2026

The online version contains supplementary material available at 10.1038/s41598-026-35933-4.

Water environment research : a research publication of the Water Environment Federation • 2026

Seafood processing wastewater contains high concentrations of organics and nutrients that need to have an effective solution. This study aims to explore the use of granular sludge in seafood wastewater treatment using anaerobic-anoxic-aerobic (AAO) process. The results showed that the granular sludges were successfully cultivated from the traditional activated sludge sources. The bioreactor demonstrated robust treatment performance, achieving a high chemical oxygen demand (COD) removal efficiency exceeding 93%, total nitrogen (TN) removal ranging from 56.6% to 68.6%, and ammonium removal (NH 4 + -N) of 80% to 88.57%. However, total phosphorus (TP) removal efficiency was relatively moderate at 47.36% ± 10.33%. Metagenomic analysis (16S rRNA) revealed a diverse and evenly distributed microbial community within the granular sludge. In anaerobic granular sludge, the dominant phylum was Bacillota (45.3%), followed by Thermodesulfobacteriota (18.2%) and Synergistota (11.24%), with minor contributions from Campylobacterota (7.58%), Chloroflexota (3.98%), and Bacteroidota (3.6%), alongside other less abundant phyla (10.1%). Anoxic granular sludge exhibited a shift, with Pseudomonadota (32.87%) and Thermodesulfobacteriota (25.08%) dominating, while Bacillota (11.95%), Bacteroidota (7.9%), and Chloroflexota (4.1%) contributed less, and other phyla comprised 18.21%. For aerobic granular sludge, Pseudomonadota represented the most prevalent phylum (42.21%), followed by Thermodesulfobacteriota (14.94%) and Bacillota (14.87%), with lower abundances of Bacteroidota (7.74%) and Chloroflexota (4.91%), while other phyla accounted for 15.42%.

Environmental research • 2026

Per- and polyfluoroalkyl substances (PFASs) are highly persistent pollutants that disrupt plant-microbe interactions and compromise the performance of constructed wetlands (CWs). Here, we demonstrate a synergistic strategy combining carbon dots (CDs) and arbuscular mycorrhizal fungi (AMF) to alleviate PFAS-induced stress and enhance CW remediation efficiency. CD amendment markedly improved plant physiological performance under PFAS exposure, increasing photosynthetic efficiency and antioxidant enzyme activities, while simultaneously facilitating AMF colonization. Under high PFAS concentrations, the AMF-CDs treatment increased AMF colonization density by 33.3-100% relative to AMF alone, indicating substantial protection of symbiotic functionality. Metagenomic and community analyses revealed that the AMF- CDs combination reshaped the rhizosphere microbiome, enriching taxa such as Chloroflexi, Planctomycetes, and Campylobacterota that are functionally linked to nitrogen cycling, PFAS transformation, and metabolic resilience. These microbial shifts enhanced nutrient turnover and strengthened redox coupling processes critical for pollutant degradation. Consequently, the AMF-CDs system achieved pronounced improvements in water quality, with total phosphorus (TP), chemical oxygen demand (COD), total nitrogen (TN), and NH 4 + -N removal efficiencies elevated by 34.3-158.3% compared with untreated controls. This study provides the first evidence that CDs function as nano-bridging agents that stabilize the root-microbe interface, reinforce AMF-plant symbiosis, and drive microbial community specialization toward pollutant degradation. The AMF-CDs synergistic mechanism offers a sustainable and scalable nano-bio strategy for restoring PFAS-contaminated ecosystems and advancing next generation constructed wetland technologies.

Environment international • 2026

Anthraquinone (AQ) is known to accelerate biochemical reactions. This study investigated the mechanisms by which AQ supplementation enhanced the performance of a denitrifying phosphorus removal (DPR) system under perfluorooctanoic acid (PFOA) inhibition, compared to natural recovery conditions. Results showed that supplementation with 100 μmol/L AQ obviously improved the removal efficiencies of PO 4 3- -P, total nitrogen, and chemical oxygen demand (COD), reaching 2.26-, 1.16-, and 1.09-fold higher, respectively, than those in the control group. Concurrently, AQ increased the activities of polyphosphate kinase (PPK), polyphosphate exopolymerase (PPX), and nitrate reductase (NAR) by 2.16-, 1.45-, and 1.19-fold, respectively, relative to the PFOA stress period. Furthermore, the addition of AQ stimulated the growth of AQ-degrading denitrifying polyphosphate-accumulating organisms (DPAOs), which catalyzed the redox conversion between AQ and hydroquinone. This redox cycling generated electrons that facilitated more efficient electron exchange among microbial populations. The increased relative abundance of DPAOs correlated with elevated abundances of key genes involved in nitrogen metabolism, phosphorus cycling, and internal carbon storage pathways, thereby contributing to an overall improvement in metabolic performance under PFOA stress.

Journal of environmental management • 2026

Saline wastewater can cause severe damage to the natural environment, yet its physicochemical treatment methods are generally energy-intensive and costly. In this study, a novel straw foam-based aerobic granular sludge (SF-AGS) was employed to protect microbial communities from salinity stress under three experimental conditions: no salinity (R1), salinity with NaCl (R2), and salinity with NaCl + Na 2 SO 4 (R3). Results indicated that mature SF-AGS maintained excellent settling performance and high biomass concentration even at 4.0% salinity. The SF-AGS exhibited high removal efficiencies for COD, NH 4 + -N, TP and TN in both pure-salt and mixed-salt reactors, achieving approximately 91%, 80%, 30% and 75%, respectively, highlighting its high tolerance to high-salinity conditions without significant deterioration in overall performance. Gradual salinity increases substantially altered the microbial community composition, with halotolerant taxa such as Raineyella and Sphingopyxis becoming more abundant and salinity-driven shifts in nitrification processes indirectly affecting phosphorus removal under high-salinity conditions. These findings demonstrate SF-AGS exhibits robust salinity tolerance and its promising applicability for high-salinity wastewater treatment.

Journal of environmental management • 2026

Prolonged idle conditions pose a major challenge to aerobic granular sludge (AGS) systems by compromising granule integrity and pollutant removal performance. This study investigates the in situ reactivation of AGS after three months of static storage using two quorum sensing molecules, N-hexanoyl-L-homoserine lactone (C6-HSL) and N-octanoyl-homoserine lactone (C8-HSL). All reactors rapidly restored COD and NH 4 + -N removal efficiencies to >92% and >98%, respectively. C6-HSL significantly accelerated phosphorus recovery, reaching removal efficiencies above 90% by day 26, compared to day 34 in the control and C8-HSL groups. C8-HSL enhanced EPS secretion and granule growth, yielding the largest granule size (1210 μm), which was 1.26-fold and 1.71-fold larger than those in the control and C6-HSL groups, respectively. Metagenomic analysis revealed comparable microbial structures at the phylum level, but distinct functional responses. C6-HSL increased the abundances of phosphorus metabolism genes (ppk, ppx, ppa), while C8-HSL notably upregulated genes related to the biosynthesis of tyrosine, tryptophan, and structural polysaccharides (e.g., alginate and Psl), supporting enhanced EPS production and granule stability. These results demonstrate molecule-specific regulatory roles of individual N-acyl-homoserine lactones during AGS reactivation, linking functional recovery and structural regeneration to distinct quorum sensing pathways. This study provides mechanistic and engineering insights into an energy-efficient strategy for restoring AGS performance after prolonged ambient idle conditions, with direct relevance to the stable operation and management of full-scale wastewater treatment systems.

Bioresource technology • 2026

Stability in the anaerobic digestion (AD) of palm oil mill effluent (POME) is frequently compromised by temporal fluctuations in organic loading that cause process inhibition. This study aims to compare the effects of material conductivity on AD performance under varying feed-to-inoculum (F/I) ratios. Batch reactors were operated under mesophilic conditions (37 ± 1°C) for 54 d using carbon felt, carbon graphite felt, carbon fiber brush, and polyurethane foam at 3 g·L -1 dosage and F/I ratios of 1.45, 2.16, and 3.62 (g chemical oxygen demand (COD)/gCOD). Material addition improved solids degradation, COD removal, and volatile fatty acid reduction (p < 0.05). Carbon felt achieved the greatest improvement, increasing methane production by 39% and shortening the lag phase by up to 4.0 days, relative to the control. Statistical analysis confirmed that the F/I ratio was the dominant factor influencing methane yield and lag phase (p < 0.05), whereas material conductivity did not significantly affect performance (p > 0.05). Mechanistic investigation integrating kinetic behavior and thermodynamic evaluation found that the observed improvements were driven mainly by microbial retention, biofilm development, and stabilized syntrophic cooperation rather than conductivity-mediated electron transfer. Although direct interspecies electron transfer offers favorable donor-side thermodynamics, its acceptor-side proton demand constrains its practical expression, thereby limiting the correspondence between conductivity and performance. Overall, this study highlights that temporal shock loading commonly encountered in the continuous AD of POME systems can be effectively buffered through material addition, with stabilization driven by microbial adaptation capacity rather than conductivity-dependent mechanisms.

Environmental microbiome • 2026

Anaerobic digestion (AD) offers a cost-effective and efficient approach for wastewater treatment, but the mesophilic anaerobic digestion only well performed within a narrow temperature range, typically between 30 and 40 °C. However, lower temperatures affected the performance of AD, microbial community and granular sludge properties. Recent studies mainly focused on adding exogenous quorum sensing (QS) signal molecules to accelerate the recovery of anaerobic digestion performance under pressure conditions, while few studies on endogenous QS molecules. To investigate microbial stress adaptation mediated by endogenous QS system under stepwise temperature reduction, an Upflow Anaerobic Sludge Blanket (UASB) reactor with gradual temperature reduction from 35 to 20 °C was constructed.

Journal of hazardous materials • 2026

Xanthates are widely used collectors in sulfide ore flotation, but pose ecological risks due to their toxicity and the releasing of carbon disulfide (CS 2 ). This study systematically investigated the biodegradation of three representative xanthates-potassium amyl xanthate (PAX), potassium butyl xanthate (PBX), and potassium isopropyl xanthate (PIX)-in an oxygen-based membrane biofilm reactor (O 2 -MBfR). The O 2 -MBfR achieved over 98 % removal of all xanthates across surface loadings up to 6000 mg-COD/m 2 ·d, with corresponding COD removals of 62-90 %. While PIX exhibited slightly lower COD removal due to the slower oxidation of its branched isopropyl group, functional gene analyses revealed the co-enrichment of alcohol and sulfur oxidation genes (adh, ALDH, soxABC/XYZ, fccAB) and C-S bond cleavage genes (cynT, ssuD). Metagenomic and metatranscriptomic results showed that Pseudomonas and Rhodanobacter predominated in PIX degradation, whereas Thiobacillus, Zoogloea, and Ottowia were mainly involved in PAX and PBX oxidation. Monod kinetics indicated that PIX had the highest maximum specific degradation rate (33.85 mg/gVSS/h) and lowest sCOD decay rate constant (0.29 h -1 ), reflecting strong microbial affinity but limited mineralization. Continuous-flow treatment of real flotation wastewater achieved > 98 % xanthate and ∼85 % COD removal, confirming system robustness. These findings provide mechanistic insight into the structure-dependent biodegradability of xanthates and demonstrate the feasibility of O 2 -MBfR technology for sustainable treatment of flotation wastewater.

Journal of environmental management • 2026

Coking wastewater (CWW) contains complex, highly toxic organic compounds, posing substantial environmental risks. Conventional treatments are often ineffective in removing refractory organics, chemical oxygen demand (COD), and ammonium nitrogen (NH 4 + -N). In this study, a laboratory-scale biofilm-enhanced biological fluidized bed-biological filter (BF-BFB) system was developed for the treatment of real CWW, using a microbial consortium bioaugmented with Comamonas sp. ZF-3 as the inoculum. Preliminary comparative experiments employing different types of wastewater were conducted to evaluate the applicability of bioaugmentation, and the results demonstrated superior performance under high-concentration conditions. The BF-BFB system was then operated with high-strength influent. The integrated system showed excellent treatment efficiency, reducing COD from 858.78 to 44.21 mg/L and NH 4 + -N from 70.04 to 0.48 mg/L. Gas chromatography-mass spectrometry (GC-MS) analysis showed that most refractory compounds, including phenol and pyridine, were completely degraded or significantly reduced. Dense and stable biofilms formed in all reactor units within 30 days, with average thicknesses of 171 μm in the facultative anaerobic biofilter, 175 μm in the aerobic fluidized bed, and 161 μm in the anaerobic biofilter. Microbial analysis revealed Proteobacteria, Bacteroidetes, and Chlorobi as the dominant phyla. Simulated degradation experiments confirmed the high removal efficiency of phenol and pyridine, achieving nearly complete pyridine degradation. Based on the laboratory-scale findings, the BF-BFB system was successfully implemented in a full-scale coking wastewater treatment project in Yunnan, achieving COD and NH 4 + -N removal efficiencies exceeding 99%. This study provides an effective, scalable technical solution for treating coking wastewater.

Bioresource technology • 2026

Traditional two-stage anaerobic digestion of food waste is hindered by long retention times and low digestion rates. To overcome these limitations, an advanced liquefaction-anaerobic digestion (ALAD) process was developed and verified at both the laboratory and pilot scales. The ALAD process first dissolved organic matter from the solid to the liquid phase by supplementing a microbial consortium, and then converted the liquefied organic matter into biogas in upflow anaerobic sludge blanket reactors. A eukaryote-prokaryote mixed microcosm enriched with Saccharomycetales and Clostridium for synergistic hydrolysis and acidogenic fermentation liquefied 52.3% of solid organic matter in 6 days. Subsequent methanogenesis of the liquefied organic matter achieved 94.0% COD removal at an organic loading rate of 11 kg COD/m 3 /d and a hydraulic retention time of 1 day. Methane generation was predominantly mediated by Methanobacterium and Methanosaeta, which together accounted for 34.7% of total microbial abundance and channeled 75.9% of organic carbon into biogas. Life cycle assessment of pilot-scale experimental data showed obvious advantages of ALAD for greenhouse gas mitigation and resource conservation. This study developed a scalable strategy for effective and sustainable resource recovery from food waste.

Bioresource technology • 2026

To enhance the performance of endogenous partial denitrification (EPD) systems, different iron valence states (nano-zero-valent iron (nZVI), Fe(II), and Fe(III)) were introduced, and their effects on microbial communities and metabolic pathways were investigated using metagenomics. The results indicated that iron supplementation significantly improved the removal of COD, NO 3 - -N, and PO 4 3- -P, as well as NO 2 - -N accumulation. Notably, Fe(III) proved most effective, achieving a NO 2 - -N accumulation of 27.7 ± 3.7 mg/L and a PO 4 3- -P removal efficiency of 64.7 ± 7.5%, whereas excessive Fe(II) and Fe(III) (40 mg/L) inhibited NO 2 - -N accumulation. While the overall microbial community structure remained stable, iron addition enriched specific denitrifying and phosphorus-accumulating genera such as Candidatus Competibacteraceae (1.36%, 2.40%, 2.30%), Candidatus Competibacter (0.40%, 0.65%, 0.62%), and Thauera (3.02%, 1.76%, 3.00%). nZVI promoted carbon utilization and denitrification gene expression, enhanced the including endogenous carbon transformation and nitrogen metabolism. In contrast, Fe(II) and Fe(III) enhanced NO 2 - -N accumulation by suppressing key genes (nirS/nirK, norB, nosZ) and shifted phosphorus metabolism toward chemical removal as the dominant pathway. Exogenous iron optimizes the performance of the EPD system by downregulating iron metabolism genes (afuA, fbpA, and afu) to mitigate iron toxicity stress. These findings provide theoretical support for optimizing EPD systems and improving nutrient removal in wastewater treatment.

Bioresource technology • 2026

Low temperatures suppress microbial growth and metabolism activity and pollutant removal in wastewater treatment systems. This study systematically compared shaping effect of micro electric fields (MEF) and pulsed electric fields (PEF) on municipal wastewater treatment by a microalgae-bacteria system (MBS) at 5 °C, 10 °C, and 15 °C. Both electric field modes showed significant improvement in cell biomass accumulation, photosynthetic pigment synthesis, and nutrient and COD removals compared to non-electrified controls. Under identical operating conditions, MEF and PEF exhibited distinct electrobiological modulation behaviors, MEF promoted more stable cell biomass-pollutant coupling under cold stress, whereas PEF provided stronger short-term stimulation at moderately low temperatures. Energy analysis showed that PEF reduced volumetric energy consumption by 20-50% compared with MEF. Overall, a coupled process of microalgal-bacterial consortia and PEF offers an energy-efficient, non-thermal complementary strategy to conventional thermal approaches for wastewater management under low-temperature conditions.

Water research • 2026

Semi-coking wastewater (SCWW) contains toxic compounds that threaten both human health and ecosystem integrity. In this study, an anaerobic ammonium oxidation (anammox)-based simultaneous partial nitrification, anammox, and denitrification (SNAD) process, enhanced with a novel polyvinyl alcohol/phytic acid/iron (PVA/PA/Fe) hydrogel carrier, was evaluated for treating actual SCWW. During long-term operation, the system achieved removal efficiencies of 90.8 % for ammonium nitrogen (NH 4 + -N) and 91.4 % for chemical oxygen demand (COD) in SCWW. The PVA/PA/Fe carrier facilitated sludge aggregation, enhanced extracellular polymeric substance secretion, and successfully enriched key functional microbes, encompassing anammox bacterium Candidatus Brocadia and phenol-degrading denitrifier Ottowia. Acute toxicity assays and nitrogen removal inhibition tests identified phenyl cyanate as a major toxicant in SCWW. Molecular docking confirmed its strong binding affinity for critical enzymes such as hydroxylamine oxidoreductase (Hao) and nitric oxide reductase (Nor). Adsorption experiments and density functional theory (DFT) calculations revealed that the PVA/PA/Fe effectively adsorbed phenyl cyanate via Fe-mediated coordination, with an adsorption capacity of 10.59 mg g -1 . This capacity was sixfold greater than that of the unmodified carrier, substantially lowering the environmental concentration of phenyl cyanate and alleviating its inhibitory effect. Collectively, these findings provide a viable carrier-enhanced strategy for the biological treatment of SCWW.

Journal of environmental management • 2026

Soilless greenhouse cultivation generates large volumes of wastewater with high nutrient concentrations, while effective solutions for its environmentally safe management remain limited. This study compared two strategies for final wastewater treatment. In Variant A, wastewater underwent direct biological treatment in a biofilm reactor, whereas in Variant B, it was first alkalized to pH 8.5 to induce phosphorus precipitation and recovery before biological treatment. Citric acid served as the sole organic carbon source, applied at COD/N ratios of 2, 4, and 6. The study evaluated nitrogen and phosphorus removal efficiency, citric acid utilization, sludge characteristics, and bacteriobiome dynamics. Preliminary alkalization enabled recovery of over 95% of phosphorus and improved denitrification, resulting in effluent nitrogen and phosphorus concentrations below discharge limits. Denitrification was efficient across a wide pH range (2.45-8.97), and citric acid supported complete denitrification despite inhibitory effects of increased alkalinity from nitrate reduction or post-alkalization conditions. The COD/N ratios required for complete denitrification were 3.16 ± 0.16 (Variant A) and 3.14 ± 0.10 (Variant B). Higher COD/N ratios enhanced pollutant removal rates and reduced hydraulic retention time. Alkalization had a stronger impact on bacteriobiome composition than on metabolic activity, with structural transformations proving more critical than changes in microbial abundance. Dominant genera included Castellaniella, Paracoccus, and Trichococcus, depending on treatment variant and COD/N ratio. Overall, the two-stage strategy integrating alkalization with citric acid-driven biological denitrification provides an effective and sustainable solution for managing nutrient-rich wastewater from hydroponic systems.

Journal of environmental management • 2026

The application of aerobic granular sludge (AGS) technology for treating real, low-concentration sewage (0.89 ± 0.26 kg COD/m 3 ·day; COD: 195.6 ± 57.8 mg/L; C/N 9:1 C/N 9:1) at a pilot scale was investigated. Two sequencing batch reactors (SBRs) were started up with no inoculum and operated with different cycle configurations. SBR1 operated on a 4-h cycle with a 40-min non-aerated phase followed by 180 min of aeration, while SBR2 had a 15-min non-aerated phase followed by 205 min of aeration, treating real sewage to determine how feeding phase duration influences granulation, EPS dynamics, and nutrient removal under high-temperature and low-strength conditions. AGS formation occurred within 80 and 48 days in SBR1 and SBR2, respectively. Both reactors achieved COD and ammonia removal rates of over 70% and 80%, respectively. SBR1 showed superior COD removal (83 ± 8% vs 74 ± 15%) due to higher biomass retention, while SBR2 exhibited faster granulation and higher average EPS (203 ± 109 vs 157 ± 137 mg/g VSS). Nitrite accumulation in SBR1 (8.2 ± 5.3 mg/L) reflected free ammonia inhibition of NOB, whereas SBR2 produced more nitrate (4.4 ± 4.2 mg/L). EPS declined sharply to 33-49 mg/g VSS under low F/M ratios (<0.3 kg COD/kg VSS·d), indicating endogenous metabolism and structural maintenance. Microbial analysis revealed EPS-producing genera (Mesorhizobium 25.9% in SBR1; Paracoccus 24.2% and Devosia 10.3% in SBR2) that enhanced stability but limited complete denitrification under the tested conditions. These findings demonstrate that shorter non-aerated feeding accelerates granulation but can also reduce biomass retention, while longer feeding enhances pollutant removal but results in slower startup, these results provide critical design parameters for tropical AGS implementation with real sewage.