Environmental Science: Water Research & Technology最新文献

Stormwater runoff is increasingly recognized as an alternative water resource, but organic micropollutant (OMP) contamination poses challenges to its safe harvesting. This study systematically reviews stormwater treatment systems to assess their effectiveness in OMP removal and their potential to mitigate associated risks. Among nature-based solutions (NBS), biofilters demonstrate high removal efficiency (>80%) for most tested OMPs. A significant positive correlation was found between hydrophobicity (log K_ow) and removal efficiency (p < 0.05; Pearson and Spearman correlation), suggesting adsorption as the dominant mechanism for hydrophobic compounds, while biodegradation plays a key role in removing many hydrophilic OMPs. Key design features, such as vegetation, submerged zones, and filter media amendments (e.g., biochar, compost), further enhance treatment performance. Constructed wetlands generally achieve removal rates above 60% mainly for hydrophobic OMPs, though challenges remain for emerging refractory pollutants such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Porous pavements are effective for polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs), particularly with adsorptive materials and geotextile layers, but limited studies restrict broader implementation. Ponds and swales exhibit variable performance, effectively treating PAHs and pesticides but showing lower efficiency for pharmaceuticals and plasticizers. Advanced oxidation technologies demonstrate strong potential, achieving >80% removal for tested PAHs, pesticides and corrosion inhibitors within minutes to hours, making them suitable for post-treatment applications. Despite progress, data gaps hinder robust assessments of design and operational parameters. Future research should focus on optimizing nature-based solutions (NBS) through smart sensors, real-time control strategies, and hybrid approaches integrating advanced oxidation technologies to enhance OMPs removal in stormwater harvesting systems.

Chemical kinetics models, typically formulated as systems of ordinary or partial differential equations, are valuable tools for simulating drinking water quality. However, these models often face inaccuracies due to discrepancies between the laboratory and the real-world conditions, as well as limitations in experimental analytical methods, hindering the accurate representation of the true underlying chemical mechanisms. In this study, we propose a physics informed neural network (PINN), using the eXtreme Theory of Functional Connections, to improve the prediction of chemical concentrations over time. The PINN method accounts for imperfect chemical models and incorporates partial data to improve predictions. Focusing on reactions describing water disinfection residual and disinfectant byproduct formation, which are crucial for public health and regulatory compliance, we demonstrate that the PINN model is able to accurately predict the concentrations of chemical species across various pH values. Notably, the model extends its accuracy to predict concentrations of chemical species not originally included in its training data. The developed method can be extended to a variety of chemical systems, offering a wide array of potential applications.

Globally, the rapid increase in non-sewered sanitation services is leading to the accumulation of large quantities of faecal sludge (FS) that need to be safely collected and treated. Pyrolysis is a promising technology for FS sterilisation and resource recovery, however, there is still limited knowledge on the properties and recovery potential of FS chars produced at scale. This study assessed the agricultural and solid fuel value of chars produced at an operating treatment plant in Uganda, that treats FS (from pit latrines and septic tanks) and local biomass waste (sawdust and bagasse). Results were compared with findings for laboratory-prepared excreta chars (from mixed or separated faeces and urine) to identify optimisation pathways via sanitation source control. The phosphorus content of FS chars was promising (4% P w/w), but nitrogen and potassium levels were relatively low compared to typical fertiliser requirements. Feedstocks from urine-diverting toilets could enable further nitrogen recovery from urine and maximise the total nutrient recovery potential. Heavy metal levels were below threshold values published in Uganda, although a need for regulatory guidelines specific to char-based fertilisers was identified. Outlier values were observed, highlighting the importance of regular quality control testing. Solid fuel briquettes prepared from carbonised FS and biomass waste were incorporated into the local market, mainly due to their slow burning properties and affordability, and despite their low calorific value compared to commercial standards (HHV = 12.5–16 MJ kg⁻¹). The high ash content of FS chars (∼70% w/w) was the limiting factor for improved briquette quality, hence source control to limit inorganic contaminants (e.g. lining latrines) and urine diversion to separate organic and inorganic excreta streams were identified as suitable interventions to maximise the energy value of FS-derived briquettes (HHV = 20–22 MJ kg⁻¹ possible for outputs of source-separating toilets mixed with biomass waste). This research provides novel field-based insights into FS pyrolysis in low-income settings, highlighting the importance of both strategic sanitation design and improved treatment efficiency to maximise resource recovery at scale.

Water resource recovery facilities (WRRFs) across the country have implemented primary sludge (PS) and return activated sludge (RAS) fermenters to generate soluble carbon and volatile fatty acids (VFA) needed for biological nutrient removal (BNR). In this study, SUMO simulations were utilized to capture fermentation trends of PS and RAS, coupled with experimental data. Additionally, through this work, key parameters for modeling of hydrolysis were identified. The reduction factor for anaerobic hydrolysis (η_HYD), the yield of H₂ during fermentation, and the rate of methanogenic growth were found to be crucial parameters when modeling PS and RAS fermentation. Two different hydrolysis models were used to calibrate the experimental data, SUMO1 and a modified version of the SUMO1 model (SUMO1_mod); the latter as a dual hydrolysis model that distinguishes between slowly biodegradable COD from influent sources (X_B) and from endogenous biomass decay (X_BE). The results of this study showed that several factors in the overall hydrolysis rate equation changed with an increase in the proportion of PS blend. Firstly, with an increasing PS percentage, the product of the hydrolysis rate and η_HYD increased due to the higher X_B from influent, as opposed to the slower degrading X_BE from biomass decay. The best fitting anaerobic hydrolysis reduction factor and hydrolysis rate product shifted from 0.2 to 0.4 for the SUMO1 model, and 0.12 to 0.3 as a weighted average based on the PS/RAS ratio for the SUMO1_mod SUMO1 model. Additionally, the composition of the solids changed with an increase in PS percentage, resulting in a much lower proportion of heterotrophic biomass (X_Het) per g VSS but a higher X_B content per g VSS. Finally, the model structure changed as the solids composition changed, impacting the hydrolysis rate. With 100% RAS fermentation, both X_B and X_Het concentrations affected the rate following Monod-like kinetics. However, as the PS content increased, the model indicated that the rate kinetics might be influenced only by the X_Het content. This work provides guidance and a framework through which modeling can be used to predict fermentation rates that can be achieved through combined PS and RAS fermentation.

Biofouling affects over 45% of seawater desalination reverse osmosis (SWRO) membrane systems, impeding the advancement of this technology. Notably, there is a positive correlation between membrane fouling potential and resistance to chlorine. Therefore, understanding the fouling mechanism of chlorine-resistant bacteria (CRB) provides a new perspective for controlling bacterial biofouling in SWRO systems. In this study, ten CRB were isolated from biofouled SWRO membranes at a nuclear power plant in China. All these bacteria demonstrated strong capacity for biofilm formation, characterized by the presence of high-molecular-weight exopolysaccharides, with protein content exceeding that of polysaccharides in the biofilm matrix. The primary monosaccharides in these exopolysaccharides were glucose and mannose, which enhanced the integrity of the extracellular polymeric substances (EPS) and contributed to the formation of robust, viscous biofilms. Infrared (IR) spectroscopy confirmed the presence of α-1,4 glycosidic linkages and amide II bonds, which are associated with biofouling in the EPS. The findings provide insights into the control of membrane biofouling in SWRO systems.

Mainstream anaerobic biological secondary treatment of wastewater can reduce energy demand and biosolids production, but forms sulfides that interfere with disinfection for non-potable or potable wastewater reuse. In this study, pilot-scale anion exchange columns were evaluated for sulfide removal from a staged anaerobic fluidized membrane bioreactor (SAF-MBR). PWA5, a type 1 strong base anion exchange resin, performed best among four resins for removing sulfides from a synthetic solution with 160 bed volumes (BVs) treated before 20% breakthrough. Increasing the pH of SAF-MBR effluent to 8.6 doubled the number of BVs treated before 20% sulfide breakthrough from 22 BVs to 46 BVs, while removing 30% of DOC, 80% of UV₂₅₄, and 90–95% of anionic surfactants. The NaCl brine used to regenerate the columns was treated with H₂O₂ to oxidize sulfides to elemental sulfur for recovery. Reuse of the NaCl brine over 5 anion exchange treatment cycles indicated no decline in sulfide removal performance. Operating cost estimates based on results from experiments with a two columns in series configuration and 5 cycles of brine reuse ($0.42 per m³) were competitive with previous estimates for direct sulfide oxidation by H₂O₂ in SAF-MBR effluent, with costs decreasing to $0.33 per m³ for 10 cycles of brine reuse.

Sewage discharges to aquatic environments present a real danger to human and ecosystem health. Event duration monitors (EDMs) from combined stormwater overflows (CSOs) are now fitted to over 90% of storm overflows in England and Wales. These have transformed our understanding of consented and non-consented discharges of sewage and wastewater from UK water companies. In 2018, Southern Water Services Ltd launched “Beachbuoy” which is an online ‘near’ real-time platform to inform customers when EDMs have been activated at particular CSOs and bathing water sites. Since April 2022, this water company categorized CSO discharges as genuine, genuine but non-impacting, and not genuine (false alarms by EDMs). We analyzed Beachbuoy data to provide an overview of CSO discharges and EDM activity and performance in the region. Across all assets, between December 2020 and February 2023 there were 7 164 656 genuine (impacting and non-impacting) minutes of discharges of which 19% overall were regarded as non-impacting of bathing water locations. Non-impacting discharges from all assets often persisted beyond multiple tidal cycles suggesting the impacts on bathing waters may need to be reevaluated. Discharges classed as ‘not genuine’ (false alarms) were highly variable between CSO for which some recorded false discharges 100% of the time. There were very strong correlations between the triggering of genuine and not genuine discharges and time of the day. Overall, 39% of all total minutes discharged and 14% of discharge events were classified as not genuine. Sewage releases from CSOs were more likely to happen between 7–10 am indicating that earlier morning patterns in human behaviours are substantially impacting the infrastructure's ability to tackle increased capacity in the system through precipitation. We discuss the appropriateness of classifying sewage discharges as ‘non-impacted’ and whether data should also be obtained on false negative discharges (EDMs not activating) as well as false positive discharges (not genuine). We call for better transparency of the data and models used by the water industry and regulation of how this information is presented to the public.

The growing interest in microbial adsorbents for heavy metal remediation arises from their inherent safety, efficiency, and environmental compatibility. In this study, isolates of Agrobacterium tumefaciens GV3101 (ATG) were selected for their exceptional tolerance to Hg(II). Under optimized in vitro conditions, biosorption assays demonstrated a maximum Hg(II) removal efficiency of 92.70% and an adsorption capacity of up to 322.72 mg g⁻¹. Thermodynamic analyses revealed that the adsorption process was spontaneous and endothermic. Systematic optimization via the response surface methodology based on the Box–Behnken design (RSM-BBD) clarified the influence of key variables on adsorption performance. Mechanistic studies indicated that Hg(II) adsorption critically relies on abundant surface-exposed active sites enriched with functional groups—particularly nitrogen- and sulfur-containing moieties—that facilitate efficient binding and removal from aqueous solution. This work presents a novel Agrobacterium strain as a highly effective biosorbent for mercury, highlighting the potential of diverse microbial resources for sustainable wastewater treatment.

Aerobic granular sludge technology faces a significant challenge regarding slow startup time when dealing with real wastewater. The present study introduces an innovative approach to decrease the granulation time while maintaining a substantial degree of organic and inorganic pollutant extraction. With this new strategy, aerobic granulation in an SBR is improved and accelerated by adding a cationic polymer. Hydrofloc cationic polymers were used to augment granule formation. Results show that adding a cationic polymer dosage of 15 ppm accelerated the formation of granules, reducing the reactor startup time. In the initial days, COD efficiency fluctuated due to the reactor's instability because of biomass discharge in the effluent. However, the COD removal efficiency reached 97 ± 1.5% after 15 days of operation of the reactor. NH₄⁺–N, total phosphorus (TP), and total nitrogen (TN) removal efficiencies were 97%, 63%, and 76% on average throughout the 16–50 day stable operating stage. The findings suggest that using a cationic polymer can enhance the granulation process in an aerobic granular system.

Persistent organic pollutants (POPs) are dangerous for the human body and for the environment, due to their high chemical stability at low concentrations and low biodegradability. Traditional treatment plants are inadequate or inefficient, making their removal from water very difficult. Unlike most existing studies that rely on synthetic wastewater, the novelty of this work lies in studying the photocatalytic degradation of POPs in real urban wastewater using titanium dioxide-based slurry reactors. A distinctive contribution of this work also lies in the comparison of two reactor configurations (internal vs. external UV sources), supported by finite element modelling (FEM) to simulate and optimize light distribution. The results showed that the configuration with an immersed lamp, which ensures better light distribution, leads to enhanced catalytic activity at lower photocatalyst concentration and low light power. This optimal configuration was subsequently applied in a slurry photocatalytic membrane reactor (SPMR), resulting in improved pollutant removal efficiency. In particular, experimental results demonstrated that using an inorganic membrane with a molecular weight cut-off of 1 kDa achieved approximately a 15% increase in pollutant removal efficiency. This integrated, experimentally validated approach addresses a critical gap in translating lab-scale photocatalysis research to real wastewater treatment.