Biofouling remains a major limitation in UF membrane performance, with EPS playing a central role. This study employs an integrative physicochemical-biological approach to investigate fouling by EPS derived from biofilms grown in fluidized bed (FLB) and fixed bed (FB) reactors under controlled aquatic conditions. Despite distinct microbial communities, both EPS types exhibited consistent fouling trends, with increasing ionic strength, calcium concentration, and decreasing pH leading to higher fouling. EPS from the FB reactor demonstrated higher fouling propensity, associated with larger molecular size (up to similar to 3500 kDa), lower negative charge, and a lower protein-to-polysaccharide ratio (i.e., relatively higher polysaccharide content). This compositional shift is consistent with the formation of more cohesive and compact EPS layers. A hybrid LSPR-QCMD approach enabled direct characterization of EPS interfacial properties, revealing a strong correlation between adsorbed dry mass and fouling behavior (R-2 = 0.95, p < 0.001). In parallel, QCMD analysis showed that increased viscoelasticity and reduced hydration of the EPS layer were associated with higher fouling severity, linking EPS composition to interfacial structure and hydraulic resistance. These findings demonstrate that EPS interfacial properties govern UF fouling behavior and that aquatic conditions exert a controlling influence on EPS-membrane interactions. From an engineering perspective, the identified relationships between water chemistry, EPS composition, and fouling provide actionable guidance for optimizing pretreatment strategies and if possible, operating conditions (e.g., ionic strength and pH control), to mitigate fouling in membrane-based water treatment systems.

The reuse of municipal wastewater is crucial to the development of new water resources, especially for agriculture. A challenge to the long-term sustainability of this approach is the presence of organic foulants in the feed water. While purification using a reverse osmosis (RO) membrane can effectively desalinate wastewater effluent to produce potable water, the main drawback is fouling of the membrane by the accumulation of a layer of organic matter from the effluent. Therefore, monitoring the propensity of pre-treated feed water to foul the RO membrane is essential for robust continuous RO operation. Electrical impedance spectroscopy (EIS), silt density index (SDI), turbidity measurement, and side stream membrane modules have been employed to predict fouling and enabling scheduled membrane cleaning. While superior RO fouling prediction capabilities were shown for EIS, other methodologies commonly provide quick but inaccurate assessments or accurate assessments at timescales too long to be useful in preventing fouling. This study investigated an innovative RO fouling prediction methodology, localized surface plasmon resonance (LSPR) sensing. We compared LSPR with predictions using SDI and a recently suggested quartz crystal microbalance with dissipation technique. The LSPR method showed high-sensitivity detection to model and environmental fouling agents by quantifying real-time foulant adsorption to the sensor surface. Our findings demonstrate that LSPR can surpass the traditional SDI method in predicting fouling propensity, likely owing to its high sensitivity to adsorbed material up to tens of nanometers from the sensor surface. LSPR thus offers a precise method of predicting RO membrane fouling that can potentially enable proactive fouling management, enhancing the longevity of membranes and reducing downtime during their operation. Synopsis Continuous wastewater reverse osmosis desalination ensures sustainable water resources, with fouling prediction via LSPR sensing vital for minimizing downtime and optimizing system efficiency.

This study examines how ferric chloride (FeCl3) dosing influences membrane fouling in an anaerobic membrane bioreactor (AnMBR) treating real municipal wastewater, with emphasis on sludge and extracellular polymeric substances (EPS) properties. A multiscale framework was applied, integrating soluble microbial products (SMP) filtration, sludge dewaterability and rheology, and nanoscale characterization of EPS-membrane interactions using quartz crystal microbalance with dissipation and localized surface plasmon resonance (QCM-D-LSPR). Moderate FeCl3 dosing (5 mg L- 1) delayed permeability decline relative to both the control and higher dosing (20 mg L- 1). These trends were not explained by biomass accumulation alone, but were associated with concurrent changes in soluble-organic fouling propensity, sludge dewaterability, EPS composition, and interfacial structure. A key contribution of this work is the use of QCM-D-LSPR to resolve EPS-associated interfacial water, enabling separation of dry adsorbed mass from hydrated coupled mass at the membrane-mimetic interface. More water-rich EPS layers were associated with increased filtration resistance and earlier fouling, while the 5 mg L- 1 condition formed a denser, less hydrated interfacial layer. Together, the results show that FeCl3 dosing modulates fouling through coupled soluble, interfacial, and bulk-scale effects. This work highlights EPS-associated interfacial water as an important contributor to AnMBR fouling under realistic wastewater conditions and demonstrates the value of hybrid QCM-D-LSPR measurements for resolving fouling-relevant EPS properties.

Reverse osmosis (RO) desalination is critically impaired by membrane fouling caused by the accumulation of organic matter, inorganic scales, and other contaminants; however, existing fouling indices often provide limited insight into interfacial fouling processes and their relation to membrane performance. Here, we explore localized surface plasmon resonance (LSPR) sensing as an approach for probing fouling processes during seawater RO desalination. LSPR sensors were engineered to mimic the surface chemistry of commercial polyamide RO membranes through an aromatic oligoamide coating and applied to model and real seawater systems. Fouling by organic compounds, silica-associated scaling, dissolved crude oil fractions, and real seawater before and after pretreatment was monitored in real time through shifts in the plasmonic extinction peak. LSPR detected early foulant accumulation (~5–200 ng cm−2) within ~20 min of exposure and exhibited strong correlations with RO fouling behavior (RPearson up to 0.891, p < 0.001). Beyond fouling prediction, LSPR provided insight into distinct interfacial fouling processes including protein aggregation, silica-associated fouling under undersaturated conditions, organic-assisted silica deposition, and hydrocarbon adsorption. Notably, organic matter enhanced silica-associated fouling even under mildly undersaturated conditions, indicating the importance of organic–inorganic coupling during fouling initiation. Experiments with real seawater further showed that pretreatment markedly reduced interfacial foulant accumulation despite comparable bulk total organic carbon (TOC) concentrations. Altogether, these findings demonstrate the potential of nano-plasmonic sensing as a diagnostic platform for investigating interfacial fouling processes and improving fouling assessment in seawater desalination systems.

Bisphenol A (BPA) and atrazine are contaminants of emerging concern (CECs) that commonly accumulate near microbial biofilms in environmental and engineered systems. Because some bacteria can biodegrade CECs, understanding the proliferation of sessile microorganisms at solid-liquid interfaces is important. Quartz crystal microbalance with dissipation monitoring (QCM-D) enables real-time analysis of sessile bacterial growth, although frequency shifts can be complex due to viscoelastic effects, including overtone-dependent sign changes. Here, QCM-D responses were compared for two sessile cultures: a BPA-degrading bacterium and an atrazinedegrading consortium. BPA degradation was associated with negative frequency shifts across all overtones, whereas atrazine degradation produced both positive and negative frequency shifts depending on overtone. In contrast, dissipation shifts increased consistently for all overtones in both systems following exposure to the biodegradable CECs. These results demonstrate that dissipation shifts provide a robust indicator of sessile bacterial proliferation, even when frequency responses are ambiguous or exhibit sign reversals.

Biofouling in electrochemically driven water treatment processes, like electrodialysis (ED), is of critical concern due to its effect on ion fluxes and energy consumption. Biofilm formation begins with microbial adhesion to surfaces mediated by extracellular polymeric substances (EPS). In ED, ions are removed from water by external electric field through charged ion exchange membranes (IEMs). While this process is well established, the influence of the ED specific conditions on EPS adsorption remains poorly understood. Brackish water biofilms were grown on cation and anion exchange membranes (CEM & AEM) in an ED cell, with and without electric fields. Biofilm viability and EPS were analyzed by confocal laser scanning microscopy (CLSM), while EPS adhesion properties were characterized using Electrochemical Quartz Crystal Microbalance with Dissipation (E-QCMD), applying chronoamperometry (CA) and cyclic voltammetry (CV). Zeta potential analysis showed all EPS samples were negatively charged, with charge density influenced by membrane type and electric field. Positively charged AEMs accumulated more highly negative EPS, whereas less negative fractions preferentially attached to negatively charged CEMs. Applied electric fields results in EPS fractions with reduced negative zeta potentials on both membranes due to electrostatic repulsion on CEMs and selective attraction of less negative EPS to AEMs under shear. CA E-QCMD results indicated stronger electrostatic responses for AEM derived EPS, while CEM derived EPS interactions were mainly hydrophobic. CV analyses revealed that EPS from both membranes formed more compact and stable layers after exposure to negative potentials, regardless of field conditions during formation, highlighting the dominance of hydrophobic interactions. Biofouling caused greater ion flux decline on AEMs, correlating with higher EPS and biomass accumulation. These findings improve understanding of biofouling mechanisms in electrically driven membrane systems, supporting improved ion transport, membrane performance, and energy efficiency.

Anaerobic membrane bioreactors (AnMBRs) have emerged as an appealing technology for wastewater treatment. However, organic fouling, particularly by soluble microbial products (SMP), presents a major challenge to their operation. The characteristics of the organic fractions comprising SMP affect the degree and reversibility of membrane fouling. However, fractionating SMP to identify the components most responsible for fouling remains difficult. Advanced methods are required to investigate the interactions between organic matter and membranes. This study presents a robust method for fractionating SMP using reverse-phase high-performance liquid chromatography with a semi-preparative C4 reverse-phase column and a highly sensitive approach for investigating interactions between the membrane and organic matter using localized surface plasmon resonance (LSPR) analysis. Following optimization of the proposed method, the effect of each organic fraction on membrane fouling was investigated through ultrafiltration tests and by quartz crystal microbalance with dissipation monitoring (QCM-D) and LSPR analysis. The SMP was separated into five fractions that differed mainly in hydrophilicity and thus each affected fouling differently. However, the original SMP mixture collected from an AnMBR caused the most severe fouling and exhibited the highest accumulation on the QCM-D and LSPR membrane-mimetic sensors. This result is attributed to synergistic fouling and adsorption effects. The LSPR dry mass adsorption correlated most strongly with the ultrafiltration membrane fouling results. Combining LSPR analysis, which measures dry mass accumulation, with QCM-D, which measures hydration and viscoelasticity, enables the comprehensive assessment of fouling potential and fouling evolution over time.

Organic fouling of ultrafiltration (UF) membranes is a major drawback and therefore, a rigorous analysis of the interactions of macromolecules with the outer membrane surface as well as with the confined porous membrane structure is required. This work provides new insights into the interplay between the interactions and conformation of alginate, a model organic foulant, as it penetrates the porous structure of an UF membrane. Alginate, like other organic foulants, can adopt conformations and orientations on the membrane surface that change in response to the aqueous conditions. In this work, adsorbed alginate layers were tested on a membrane-mimetic sensor surface using a hybrid system consisting of localized surface plasmon resonance (LSPR) sensing and quartz crystal microbalance with dissipation monitoring (QCM-D). The alginate conformation and adhesion on the sensor were consistent with the effects of alginate penetrating to the UF membrane pores affecting permeability at various ionic strengths. To study the interactions and conformational changes of alginate on the surface, the membrane surface and the hybrid sensor were given a positive charge by modifying them with species bearing primary amine groups, 2-aminoethyl methacrylate and 3-aminopropyl triethoxysilane, respectively. Intriguingly, on the pristine surfaces, increasing ionic strength induced a reversible increase in alginate areal density as measured by LSPR, indicating changes in alginate conformation, which increased the effective UF membrane pore diameter and increased membrane permeability. In contrast, the modified membranes with positive surfaces did not exhibit these changes in alginate conformation caused by ionic strength and membrane permeability showed no response to the aqueous ionic strength. This novel analysis of foulant conformation on a membranemimetic LSPR sensor, was further confirmed by the standard pore blocking model. QCM-D analysis revealed the expected responses to surface charge and ionic strength, i.e., the alginate layer's viscoelasticity increased on the positively charged surface and with increasing ionic strength. These analyses at the nanometer scale provide critical mechanistic insight into the way fouling reduces UF membrane performance.

Biofouling is the main challenge in the operation of anaerobic membrane bioreactors (AnMBRs). Biofouling strongly depends on temperature; therefore, we hypothesize that the interactions and viscoelastic properties of soluble microbial products (SMP) and extracellular polymeric substances (EPS) vary with temperature, consequently influencing membrane permeability. This study compares the performance of an AnMBR operated at a similar permeate flux at two temperatures. The transmembrane pressure rose rapidly after 5 ± 2 days at 25°C but only after 18 ± 2 days at 35°C, although the reactor's biological performance was similar at both temperatures, in terms of the efficiency of dissolved organic carbon removal and biogas composition, which were obtained by changing the hydraulic retention time. Using confocal laser scanning microscopy, a higher biofilm amount was detected at 25°C than at 35°C, while QCM-D showed a more adhesive, but less viscous and elastic, EPS layer. In situ optical coherence tomography (OCT) of an ultra-filtration cell, fed with the MLSS at the two temperatures, revealed that while a higher rate of transmembrane pressure (TMP) increase was obtained at 25°C, the attachment of biomass from mixed liquor suspended solids was markedly less. Increased EPS adhesion to the membrane can accelerate TMP increase during the operation of both the AnMBR and the OCT filtration cell. EPS's reduced viscoelasticity at 25°C suggests reduced floc integrity and possible increased EPS penetration into the membrane pores. Analysis of the structures of the microbial communities constituting the AnMBR flocs and membrane biofilms reveals temperature's effects on microbial richness, diversity, and abundance, which likely influence the observed EPS properties and consequent AnMBR fouling.

Efficient tertiary effluent desalination is hindered by membrane biofouling, leading to plant downtime, shortened membrane lifespan, heightened energy consumption, and reduced permeability. While the composition of these biofouling layers is studied, little is known about bacterial succession and function. To address this, we used a benchtop reverse osmosis (RO) system to process synthetic tertiary effluent with diluted sludge. System flux monitoring tracked biofouling layer development, and RO biofilm samples were collected at early and mature stages (48, 72, 120 h). Scanning electron microscopy visualized the samples, and their 16S rRNA genes were sequenced. DNA-stable isotope probing with labeled glucose identified growing taxa in early and late biofouling stages (48, 120 h). Over time, biofouling layer biomass increased, with shifts in bacterial diversity and composition. Proteobacteria, notably oligotrophic genera, dominated early stages along with Bacteriodota, while Actinobacteria increased in mature biofilms. Functional changes included a shift from biosynthesis of cellular components like DNA, peptidoglycan, membrane lipids, and antimicrobials, to production of extracellular polysaccharides and reactive oxygen scavenging agents. In conclusion, our research enhances the understanding of biofouling dynamics within tertiary effluent desalination processes, providing insights that could improve biofouling management strategies in RO desalination systems, potentially applicable to larger-scale operations.

Nanobubbles have been increasingly used in various applications involving porous media, such as groundwater remediation and irrigation. However, the fundamental scientific knowledge regarding the interactions between nanobubbles and the media is still limited. The interactions can be repulsive, attractive, or inert, and can involve reversible or irreversible attachment as well as destructive mechanisms. Specifically, the stability and mobility of nanobubbles in porous media is expected to be dependent on the dynamic conditions and the physicochemical properties of the porous media, solutions, and nanobubbles themselves. In this study, we investigated how changes in solution chemistry (pH, ionic strength, and valence) and media characteristics (size and wettability) affect the size and concentration of nanobubbles under dynamic conditions using column experiments. Quartz crystal microbalance with dissipation monitoring provided a deeper understanding of irreversible and elastic nanobubbles' interactions with silica-coated surfaces. Our findings suggest that nanobubbles are less mobile in solutions of higher ionic strength and valence, acidic pH and smaller porous media sizes, while the wettability of porous media has a negligible influence on the retention of nanobubbles. Overall, our findings provide insights into the underlying mechanisms of nanobubble interactions and suggest potential strategies to optimize their delivery in various applications.

Harnessing prokaryotes’ metabolic capacity and adaptive potential is of interest for environmental bioremediation and biological treatment of domestic and industrial waste. Bioaugmentation is commonly implicated in the cleanup of high-dosed environmental pollution. In this study, Arthrobacter aurescens TC1 was used to augment biofiltration systems for bioremediation of stormwater micropollutant. Bioaugmentation was tested on non-vegetated and vegetated system designs, with or without an adsorbent biocarrier [granulated activated carbon (GAC)]. This study investigated how system design affects microbial function and structure. It focused on long-term metabolic responses of the biofilter’s microbiome to low chronic exposure to the herbicide atrazine and fluctuations in atrazine load. Shotgun metagenomics analyses demonstrated that the major contributor to microbiome structure was the supplementation of GAC. Vegetation affected microbiome structure mainly in sand biofilter-media. GAC showed a significant shift in atrazine-degrading genes over time compared to sand. Diversity and richness increased with time in all system designs, regardless of atrazine load fluctuations. To conclude, incorporating GAC in stormwater-biofiltration systems effectively enhances the micropollutant-biodegradation capacity in stormwater with negligible effects on the biofilter’s microbiome diversity and function.

Virus removal from water using microfiltration (MF) membranes is of great interest but remains challenging owing to the membranes' mean pore sizes typically being significantly larger than most viruses. We present microporous membranes grafted with polyzwitterionic brushes (N-dimethylammonium betaine) that combine bacteriophage removal in the range of ultrafiltration (UF) membranes with the permeance of MF membranes. Brush structures were grafted in two steps: free-radical polymerization followed by atom transfer radical polymerization (ATRP). Attenuated total reflection Fourier transform infrared (ATR-FTIR) and X-ray photoelectron (XPS) verified that grafting occurred at both sides of the membranes and that the grafting increased with increasing the zwitterion monomer concentration. The log reduction values (LRVs) of the pristine membrane increased from less than 0.5 LRV for T4 (∼100 nm) and NT1 (∼50 nm) bacteriophages to up to 4.5 LRV for the T4 and 3.1 LRV for the NT1 for the brush-grafted membranes with a permeance of about 1000 LMH/bar. The high permeance was attributed to a high-water fraction in the ultra-hydrophilic brush structure. The high measured LRVs of the brush-grafted membranes were attributed to enhanced bacteriophages exclusion from the membrane surface and entrapment of the ones that penetrated the pores due to the membranes' smaller mean pore-size and cross-section porosity than those of the pristine membrane, as seen by scanning electron microscopy (SEM) and measured using liquid-liquid porometry. Micro X-ray fluorescence (μ-XRF) spectrometry and nanoscale secondary ion mass spectrometry showed that 100 nm Si-coated gold nanospheres accumulated on the surface of the pristine membrane but not on the brush-coated membrane and that the nanospheres that penetrated the membranes were entrapped in the brush-grafted membrane but passed the pristine one. These results corroborate the LRVs obtained during filtration experiments and support the inference that the increased removal was due to a combined exclusion mechanism and entrapment. Overall, these microporous brush-grafted membranes show potential for use in advanced water treatment.

Organic matter dissolved in tertiary effluents (effluentorganicmatter, EfOM) is the predominant organic membrane foulant in tertiarywastewater reverse osmosis (RO) desalination, ultimately causing biofouling.The interrelated effects of EfOM fractions of different hydrophobicityand polarity on membrane performance were studied by (i) examiningeach fraction's overall effect on membrane permeability; (ii)analyzing the intrinsic hydraulic resistance induced by each fraction;(iii) studying their adsorption on the active layer of an RO membraneusing a quartz crystal microbalance with dissipation monitoring (QCM-D);(iv) assessing their "dry" molecular mass when adsorbedon polyamide using localized surface plasmon resonance (LSPR) sensing;(v) analyzing their hydrodynamic radii by dynamic light scattering(DLS); and (vi) characterization using excitation-emissionmatrix (EEM) analysis and parallel-factor (PARAFAC) modeling. Hydrophobicand transphilic neutral fractions (containing & SIM;12.5% totalorganic carbon) have the greatest effect on membrane flux reductionand the highest hydraulic resistance and adhere most strongly to polyamidesurfaces, resulting in the highest adsorbed "dry" mass.Therefore, in terms of their effect on RO permeate flux reduction,these fractions are the most detrimental in the EfOM mix. EEM analysisand associated PARAFAC modeling indicate that the main componentscausing this effect are mixtures of protein-like compounds, togetherwith humic-like substances. Novel LSPR-based analysis elucidated therole of the fractions most detrimental to membrane permeability throughmeasurement of dry mass surface concentration on a polyamide mimeticsensor. This study provides valuable insights into the roles of differentEfOM fractions in RO membrane fouling and enhances our understandingof fouling during tertiary wastewater desalination. The fundamental approach of this studyfor reducing RO membranefouling can improve the desalination process' energy and maintenancecosts as well as its carbon footprint.

The main reason for the deterioration of membrane operation during water purification processes is biofouling, which has therefore been extensively studied. Biofouling was shown to reduce membrane performance reflected by permeate flux decline, reduced selectivity, membrane biodegradation, and consequently, an increase in energy consumption. Studies of biofouling focused on the identification of the assembled microbial communities, the excretion of extracellular polymeric substances (EPS), and their combined role in reduced membrane performance and lifetime. However, the link between the structure and function of biofouling communities has not been elucidated to date. Here, we provide a novel insight, suggesting that bacterial functions rather than composition control biofouling traits on reverse osmosis (RO) membranes. We studied the potential activity of RO biofilms at metatranscriptome resolution, accompanied by the morphology and function of the biofouling layer over time, including microscopy and EPS composition, adhesion, and viscoelastic properties. To that end, we cultivated natural multispecies biofilms in RO membranes under treated wastewater flow and extracted RNA to study their taxonomies and gene expression profiles. Concomitantly, the biofilm structure was visualized using both scanning electron microscopy and laser scanning confocal microscopy. We also used quartz crystal microbalance with dissipation to characterize the affinity of EPS to membrane-mimetic sensors and evaluated the viscoelasticity of the Ex-Situ EPS layer formed on the sensor. Our results showed that different active bacterial taxa across five taxonomic classes were assembled on the RO membrane, while the composition shifted between 48 and 96 h. However, regardless of the composition, the maturation of the biofilm resulted in the expression of similar gene families tightly associated with the temporal kinetics of the EPS composition, adhesion, and viscoelasticity. Our findings highlight the temporal selection of specific microbial functions rather than composition, featuring the adhesion kinetics and viscoelastic properties of the RO biofilm.

Biofouling in anaerobic membrane bioreactors (AnMBRs) has not been studied widely. Moreover, the effect of membrane surface properties on biofilm formation beyond initial deposition is controversial. We investigated biofouling with polyvinyldifluoride, polyacrylonitrile, and zwitterion-modified polyethersulfone ultrafiltration membranes having different properties during 72 h filtration using natural anaerobes isolated from AnMBR and analyzed biofilm characteristics by physicochemical and molecular techniques. A decrease in membrane performance was positively correlated with biofilm formation on polyvinyldifluoride and polyacrylonitrile membranes, and as expected, physical cleaning effectively mitigated biofilm on hydrophilic and low-roughness membranes. Surprisingly, while the biofilm on the hydrophilic and low-surface roughness zwitterion-modified membrane was significantly impaired, the impact on transmembrane pressure was the highest. This was ascribed to the formation of a soft compressible thin biofilm with high hydraulic resistance, and internal clogging and pore blocking due to high pore-size distribution. Anaerobe community analysis demonstrated some selection between the bulk and biofilm anaerobes and differences in the relative abundance of the dominant anaerobes among the membranes. However, correlation analyses revealed that all membrane properties studied affected microbial communities' composition, highlighting the system's complexity. Overall, our findings indicate that the membrane properties can affect biofilm formation and the anaerobic microbial population but not necessarily alleviate biofouling.

Extracellular polymeric substances (EPSs) can conform and orient on the surface according to the applied aquatic conditions. While pH elevation usually removes EPSs from membranes, small changes in pH can change the adsorbed EPS conformation and orientation, resulting in a decrease in membrane permeability. Accordingly, EPS layers were tested with localized surface plasmon resonance (LSPR) sensing and quartz crystal microbalance with dissipation monitoring (QCM-D) using a hybrid sensor. A novel membrane-mimetic hybrid QCM-D-LSPR sensor was designed to indicate both "dry" mass and mechanical load ("wet" mass) of the adsorbed EPS. The effect of pH on the EPS layer's viscoelastic properties and hydrated thickness analyzed by QCM-D corroborates with the shift in EPS areal concentration, ΓS, and the associated EPS conformation, analyzed by LSPR. As pH elevates, the processes of (i) elevation in EPS layer's thickness (QCM-D) and (ii) decrease in the EPS areal density, ΓS (LSPR), provide a clear indication for changes in EPS conformation, which decrease the effective ultrafiltration (UF) membrane pore diameter. This decrease in the pore diameter together with the increase in surface hydrophobicity elevates UF membrane hydraulic resistance.

Sticky and gel-like extracellular polymeric substances (EPS) could provide the protective shielding and prevent the microbial cell-rupture and lysis as well as increase the difficulty of excessive activated sludge (EAS) biodegradation. Microbial fuel cells (MFCs) are able to accelerate the degradation of EPS and gain electric energy recovery from wastewater simultaneously. In order to discover the role of light stimulation on MFC performance, four reactors were operated in dark (SD), in LED light (SL), in electrogenesis (ED) and in combination of electrogenesis and light (EL), respectively. EPS characteristic, electrochemical performance and anodic microbial community structures were investigated and compared. The results showed that single light stimulation distinctly improved the total EPS especially polysaccharides content in soluble EPS, and Pseudomonas (31.85% relative abundance) as well as Acinetobacter (10.2% relative abundance) became the dominant genera. Single electrogenesis mainly promoted degradation of negatively charged proteins, which was further proved by the enrichment of typical proteolytic and amino acids fermented bacterial genera like Proteiniphilum and Cloacibacillus. Furthermore, the electrochemical activated Petrimonas and syntrophic Syntrophomonas occupied the dominant position indicating the existence of interspecific electron transfer. Moreover, the predominance of Acinetobacter (44.2% relative abundance) and Escherichia/shigella (7.09% relative abundance) in EL reactor implied the synergetic improvement of electrogenesis and light stimulation. In the interaction effect, light stimulation optimized the electricity generation and proteins degradation of MFC.

Waters contaminated with micropollutants are of environmental and public health concern globally. Stormwater is a significant source of anthropogenic micropollutants to receiving waters. Hence, sustainable stormwater remediation is needed to reduce contamination of waterways. Yet designing sustainable bioremediation solutions, including those targeted to remove micropollutants, is a major scientific challenge. This study aimed to adapt the design of stormwater biofiltration systems, to improve the removal of micropollutants and understand the role of the micropollutant-degrading bacteria in this bioremediation process. We investigated the atrazine removal performance of a prototype biofiltration system, in which the filter media was supplemented with Granulated Activated Carbon (GAC). The prototype biofiltration system completely removed atrazine to below detectable limits, significantly exceeding the GAC's adsorption capacity alone, suggesting other biological processes were present. We showed that atrazine degradation capacity, measured by the kinetics of the trzN gene abundance, was accelerated in the prototype system compared to the standard system (which had no added GAC; 0.8 vs. 0.37 week-1, respectively). Notably, this high level of atrazine removal did not come at the expense of the removal performance of other typical stormwater macropollutants (e.g., nutrients, suspended solids). The prototype biofiltration system showed a proof-of-concept of sustaining microbial remediation of a model micropollutant alongside stormwater macropollutants, which could be used to reduce impacts on receiving waterways and protect our ecosystems and human health.

Antiscalants are organic polymers widely used for scale inhibition in seawater desalination. While they are susceptible to biodegradation, they provide nutrients for bacterial cell growth and energy for the microbes that assimilate and degrade them. This paper shows the biodegradability of three commercial antiscalants (polyacrylate—CA, polyphosphonate—PP, and carboxylated dendrimers—DN) applied in seawater reverse osmosis desalination (SWRO) as well as analyzing the antiscalant’s effects on microbial diversity using microbial cultures grown in seawater, under semi-continuous batch conditions. Nutritional uptake and contribution of the antiscalants to microbial growth were investigated by measuring DOC, TDN, NO3−, NO2−, PO4−, NH4+, and TP of the filtered samples of the incubated batch, twice a month, for twelve months. The microbial community was estimated by 16S rRNA sequencing. The main changes in the microbial communities were determined by the incubation period. However, bacterial orders of the antiscalant treatments differed significantly from the control treatment, namely Planctomycetales, Clostridiales, Sphingobacteriales, Rhodobacterales, and Flavobacteriales, and other unclassified bacterial orders, which were found in various relative abundances dependent on incubation times. The results showed the PP antiscalant to be the least biodegradable and to have the least effect on the bacterial community composition compared to the control. This result emphasizes the need to reassess the suitability criteria of antiscalants, and to further monitor their long-term environmental effects.