Removal Efficiencies Of Micropollutants Research Articles

Indium-based quantum dots trapped in solid-state matrices: a one-pot synthesis, thermoresponsive properties, and enhanced micropollutant removal

Indium-based quantum dots are innovatively synthesized using a one-pot method by embedding them in insoluble oleic acid aggregates with controllable fluorescence and thermo-responsive properties, demonstrating high micropollutant removal efficiency.

Enhancement of Biological Activated Carbon (BAC) Process to Improve Removal Efficiency of Micropollutants

Objectives : In this study, the removal efficiency of micropollutants in the biological activated carbon (BAC) process was investigated, and a method for improving the removal efficiency of micropollutants in the BAC process of water treatment plants was proposed.Methods : Dibromo-methylparaben (Br<sub>2</sub>-MP) was selected as the target micropollutant. Batch and lab-scale column experiments were conducted to evaluate the removal efficiencies of Br<sub>2</sub>-MP in the conventional BAC process and the BAC with enhanced biofilm properties by the addition of phosphorus (P) and hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>). Biodegradation kinetics were evaluated using results from batch and lab scale column experiments.Results and Discussion : As a result of comparing the removal efficiency of Br<sub>2</sub>-MP in a batch experiment with the same biomass concentrations (2.0±0.2×10<sup>7</sup> cells), the biodegradation rate constant (<i>k</i><sub>bio</sub>) of the enhanced BAC process was found to be 1.2 times higher than that of the conventional BAC process due to its higher biological activity (enhanced BAC: 3.4±0.3 mg·C/g·hr, conventional BAC: 2.9±0.4 mg·C/g·hr). Comparison of removal efficiencies of Br<sub>2</sub>-MP in batch experiments with the same wet weight of BAC (1 g) showed that the biodegradation rate constant (<i>k</i><sub>bio</sub>) of the enhanced BAC process was 1.9 times higher than that of conventional BAC process due to higher biomass (enhanced BAC: 3.5±0.4 µg·ATP/g·GAC, conventional BAC: 2.3±0.2 µg·ATP/g·GAC). Through the batch experiments, the enhanced BAC process was efficient in removing Br<sub>2</sub>-MP via increasing both biomass concentrations and activity of attached microorganisms. Lab-scale column experiments conducted under different water temperatures (5 and 25℃) and empty bed contact time (EBCT: 5-40 min) conditions showed higher removal efficiency of Br<sub>2</sub>-MP in the enhanced BAC process than the conventional BAC process throughout the entire period of operation. In particular, the removal efficiency of Br<sub>2</sub>-MP between the enhanced and conventional BAC processes showed significant differences at low temperature (5℃) and short EBCT (5 min). At 5℃ and 25℃, the kbio of the conventional BAC process was 0.0229 min<sup>-1</sup> and 0.0612 min<sup>-1</sup>, respectively, and the <i>k</i><sub>bio</sub> of the enhanced BAC process was 0.0470 min<sup>-1</sup> and 0.1421 min<sup>-1</sup>, respectively, These results showed that the enhanced BAC process had two times higher biodegradability of Br<sub>2</sub>-MP than the conventional BAC process. These results showed a similar trend to the results from the batch experiment. In an experiments simulating the impact of frequent EBCT changes during summer, the enhanced BAC process maintained a relatively stable removal efficiency of Br<sub>2</sub>-MP compared to the conventional BAC process.Conclusion : The enhanced BAC process showed superior biodegradation of micropollutant compared to the conventional BAC process. Considering economic costs (e.g., costs of adding phosphate and hydrogen peroxide) and water quality, it appears to be an efficient alternative to operate the enhanced BAC process intermittently, limited to cases where EBCT is shortened, such as summer, or when water temperature is low, such as in winter.

Fe3S4/persulfate-based pre-oxidation for mitigating membrane fouling and enhancing synergistic perfluorooctanoic acid removal: Influence of pH and persulfate types

Aerobic granular sludge membrane system (AGSMS) represents a new wastewater reuse treatment technology. However, the challenges of membrane fouling and limited micropollutant removal efficiency significantly impact its potential for further application. Consequently, this study aimed to address these concerns by employing Fe3S4/persulfate pretreatment to mitigate membrane fouling and enhance perfluorooctanoic acid (PFOA) removal in AGSMS. The effects of pH and persulfate types were investigated by assessing membrane flux, fouling resistance, membrane characterization, and effluent properties. Results showed that optimal mitigation of membrane fouling and removal of PFOA were achieved using Fe3S4-activated PMS at a pH of 6. The primary mechanism for Fe3S4-activated PMS involved the generation of SO4•− and 1O2. Moreover, the fouling mechanism transitioned from cake layer fouling and intermediate blocking fouling to complete blocking fouling in the presence of Fe3S4/PMS. The application of extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory revealed that at pH 6.0, there was a significant increase in the energy barrier for both foulant-membrane and foulant-foulant interactions, leading to an effective mitigation of membrane fouling. Correlation analysis demonstrated a significant influence of polysaccharides and total phosphorus concentration on mitigating membrane fouling. Furthermore, pH played a crucial role in mitigating membrane fouling as well as pollutant removal by influencing both coexisting ion states in solution and catalyst properties. This study offers valuable insights for future research and provides essential theoretical guidance for large-scale applications of AGSMS technology in wastewater treatment.

Predicting micropollutant fate during wastewater treatment using refined classical kinetic model based on quantitative monitoring in multi-metropolitan regions of South Korea

This study aimed to implement an extensive prediction model for the fate of micropollutants (MPs) in wastewater treatment plants (WWTPs). Five WWTPs equipped with seven different biological treatment processes were monitored from 2020 to 2022 with three to four sampling events in each year, and 27 datasets for 20 MPs were collected. Among these datasets, 12 were used to investigate the behavior and fate of MPs in WWTPs in South Korea. Metformin, acetaminophen, caffeine, naproxen, and ibuprofen were the MPs with the highest influent concentrations (ranging from 3,933.3–187,637.0 ng L−1) at all WWTPs. More than 90% of MPs were removed by biological treatment processes in all WWTPs. The Kruskal-Wallis test verified that their efficacy did not differ statistically (p-value > 0.05). Meanwhile, to refine the performance of the prediction model, this study optimized the biodegradation rate constants (kbio) of each MP according to the variation of seasonal water temperature. As a result, compared to the original prediction model, the mean difference between the actual data and predicted results (MEAN) decreased by 6.77%, while the Nash-Sutcliffe efficiency (NSE) increased by 0.226. The final MEAN and NSE for the refined prediction model were calculated to be 5.09% and 0.964, respectively. The prediction model made accurate predictions, even for MPs exhibiting behaviors different from other cases, such as estriol and atrazine. Consequently, the optimization strategy proposed in this study was determined to be effective because the overall removal efficiencies of MPs were successfully predicted even with limited reference datasets.

Porous cyclopentadiene unit-incorporated graphitic carbon nitride nanosheets for efficient photocatalytic oxidation of recalcitrant organic micropollutants in wastewater

For the purpose of searching for efficient photocatalysts to deal with recalcitrant organic micropollutants in wastewater, here an in-situ supramolecule self-assembly-thermal polymerization strategy is developed to prepare a series of porous cyclopentadiene (CPD) unit-incorporated g-C3N4 ultrathin nanosheets (CCPD-g-C3N4). The CCPD-g-C3N4 demonstrate CPD unit doping level-dependent and remarkably enhanced visible-light photocatalytic oxidation efficiency towards two organic micropollutants, acetaminophen and methylparaben, in which the optimized CCPD-g-C3N4-2 shows 6.1 and 3.5 times higher acetaminophen and methylparaben degradation rate than bulk g-C3N4; moreover, CCPD-g-C3N4-2 is still robust and efficient in the treatment of five mixed organic micropollutants in pharmaceutical wastewater, and the satisfactory micropollutant removal efficiency is obtained in a wide pH window and the presence of high concentrations of inorganic anions and cations as well as dissolved organic matters. Theoretical calculation combined with experimental test reveal that CCPD-g-C3N4 can significantly reduce ecological risk of the target pollutant after the photocatalytic degradation reaction. Such enhanced photocatalytic oxidation efficiency is dominated by the accelerated charge carrier separation dynamics and extended visible-light response region due to the incorporation of CPD units, which finally lead to the generation of abundant reactive oxygen species to degrade and mineralize target micropollutants efficiently.

Poly(vinylidene fluoride) membrane with immobilized TiO2 for degradation of steroid hormone micropollutants in a photocatalytic membrane reactor

The lack of effective technologies to remove steroid hormones (SHs) from aquatic systems is a critical issue for both environment and public health. The performance of a flow-through photocatalytic membrane reactor (PMR) with TiO2 immobilized on a photostable poly(vinylidene fluoride) membrane (PVDF-TiO2) was evaluated in the context of SHs degradation at concentrations from 0.05 to 1000 µg/L under UV exposure (365 nm). A comprehensive investigation into the membrane preparation approach, including varying the surface Ti content and distribution, and membrane pore size, was conducted to gain insights on the rate-limiting steps for the SHs degradation. Increasing surface Ti content from 4 % to 6.5 % enhanced the 17β-estradiol (E2) degradation from 46 ± 12–81 ± 6 %. Apparent degradation kinetics were independent of both TiO2 homogeneity and membrane pore size (0.1–0.45 µm). With optimized conditions, E2 removal was higher than 96 % at environmentally relevant feed concentration (100 ng/L), a flux of 60 L/m2h, 25 mW/cm2, and 6.5 % Ti. These results indicated that the E2 degradation on the PVDF-TiO2 membrane was limited by the catalyst content and light penetration depth. Further exploration of novel TiO2 immobilization approach that can offer a larger catalyst content and light penetration is required to improve the micropollutant removal efficiency in PMR.

Micropollutant Removal Efficiency of Advanced Wastewater Treatment Plants: A Systematic Review.

Various review papers have been published regarding the occurrence and fate of micropollutants (MPs). MPs in the aquatic environment are still not well reviewed to generate comprehensive summaries with a special focus on their removal from wastewater using conventional and advanced treatment processes. Therefore, this review aimed to provide a synopsis of the efficiency of the advanced wastewater treatment plants in the removal of MPs. A systematic search of published literature was conducted on the National Library of Medicine (NLM) database, Web of Science, Joanna Briggs Institute (JBI) database, Scopus, and Google Scholar, based on studies with evidence of removal of MPs in the wastewater treatment process. Screening of the published articles was made using pre-specified inclusion and exclusion criteria. Amongst the 1545 studies searched, 21 full-length articles were analyzed that showed 7 treatment options related to the removal of MPs from wastewater. MPs from wastewater effluents were successfully and effectively removed by advanced treatment techniques. Advanced Oxidation Processes (AOPs), membrane processes, and adsorption processes have all been shown to be potential solutions for the removal of MPs in advanced treatment plants (WWTPs). But, there are 2 critical issues associated with the application of the advanced treatment options which are high operational cost and the formation of dangerous by-products and concentrated residues. This study identified that the removal of MPs using WWTPs was commonly incomplete with varying removal efficiency. Therefore, the adaptation and scale-up of the cost-effective and efficient combined wastewater treatment technology are vital to creating an absolute barrier to MPs emissions.

Supramolecular Engineering of Amorphous Porous Polymers for Rapid Adsorption of Micropollutants and Solar-Powered Volatile Organic Compounds Management.

Freshwater shortage is becoming one of the most critical global challenges owing to severe water pollution caused by micropollutants and volatile organic compounds (VOCs). However, current purification technology shows slow adsorption of micropollutants and requires an energy-intensive process for VOCs removal from water. In this study, a highly efficient molecularly engineered covalent triazine framework (CTF) for rapid adsorption of micropollutants and VOC-intercepting performance using solar distillation is reported. Supramolecular design and mild oxidation of CTFs (CTF-OXs) enable hydrophilic internal channels and improve molecular sieving of micropollutants. CTF-OX shows rapid removal efficiency of micropollutants (>99.9% in 10s) and can be regenerated several times without performance loss. Uptake rates of selected micropollutants are high, with initial pollutant uptake rates of 21.9gmg-1 min-1 , which are the highest rates recorded for bisphenol A (BPA) adsorption. Additionally, photothermal composite membrane fabrication using CTF-OX exhibits high VOC rejection rate (up to 98%) under 1 sun irradiation (1kWm-2 ). A prototype of synergistic purification system composed of adsorption and solar-driven membrane can efficiently remove over 99.9% of mixed phenol derivatives. This study provides an effective strategy for rapid removal of micropollutants and high VOC rejection via solar-driven evaporation process.

Adaptable Process Design as a Key for Sustainability Upgrades in Wastewater Treatment: Comparative Study on the Removal of Micropollutants by Advanced Oxidation and Granular Activated Carbon Processing at a German Municipal Wastewater Treatment Plant

Micropollutants have been increasingly detected at low concentrations in surface waters and may have harmful effects on humans, organisms, and the environment. As wastewater treatment plants are one of the main sources of micropollutants, conventional wastewater treatment methods and plants (mainly one to three cleaning stages) must be improved through an advanced (fourth) treatment stage. The optimal fourth treatment stage should be determined based not only on removal efficiencies but also on a holistic sustainability assessment that further considers the process’s adaptability, economic, environmental, and social parameters. The ability of a tertiary wastewater treatment plant to remove organic pollutants was investigated over four months using two different advanced treatment methods: (1) an advanced oxidation process (AOP) (using UV + H2O2) and (2) granular activated carbon (GAC). The resulting average micropollutant removal efficiencies were 76.4 ± 6.2% for AOP and 90.0 ± 4.6% for GAC. As the GAC became saturated, it showed a decreasing performance from 97.6% in week one to 80.7% in week 13, after 2184 bed volumes were processed. For the AOP, adjusting the UV and H2O2 doses results in higher removal efficiencies. With 40 ppm H2O2 and 10 kJ/m2 UV, a removal of 97.1% was achieved. Furthermore, the flexibility and adaptability of the AOP process to adjust to real-time water quality, along with a lower resource consumption and waste disposal, make it a more promising technology when comparing the sustainability aspects of the two methods.

폐수방류수 오존처리시 오존 및 OH 라디칼 노출량 기반 미량유기오염물질 제거 예측

Municipal wastewater is a major source of contaminants of emerging concern in aquatic environments. Many studies have proven the effectiveness of ozonation for the removal of micropollutants, though the composition of the wastewater matrix influences the oxidation potential during this process. The ozone decomposition rate consists of two stages: instantaneous ozone consumption and slower ozone decay. In particular, with instantaneous ozone consumption, 62.8-79.7% of the initial ozone injection concentration is consumed. Determining the appropriate ozone dosage for wastewater ozonation is complicated by the complexity of the wastewater matrix composition. The purpose of this study was to propose a chemical kinetic model for the prediction of micropollutant removal during the ozonation of wastewater effluent. A kinetics approach based on the measurement of ozone and hydroxyl radical(·OH) exposure was proposed to predict the micropollutant removal efficiency. In this study, a batch-type ozone reactor was set up to measure the ozone and OH radical exposure during wastewater ozonation. Ozone and OH radical exposure was proportional to the initial dose of ozone, while OH radical exposure was found to be proportional to ozone exposure, though the deviation was relatively high at 1.0 to 1.5 gO³/gDOC. The calculated OH radical exposure was 3.0×10^-10 to 5.3×10^-10M·s. Of the target micropollutants, acetaminophen, sulphamethoxazole, andnaproxen, which are highly reactive with ozone and OH radicals, exhibited a removal rate of more than 80% at an ozone injection rate of 0.75 gO³/gDOC.

Integrated adsorption and biological removal of the emerging contaminants ibuprofen, naproxen, atrazine, diazinon, and carbaryl in a horizontal tubular bioreactor

Groundwater and surface water bodies may have contaminants from urban, industrial, or agricultural wastewater, including emerging contaminants (ECs) or micropollutants (MPs). Frequently, they are not efficiently removed by microbial action due to their minimal concentration in water and the low microbiota affinity for complex compounds. This work developed a process allowing the adsorption of contaminants and their simultaneous biodegradation using horizontal tubular fixed-bed biofilm reactors (HTR). Each HTR has two zones: an equalizer-aerator of the incoming liquid flow and a fixed bed zone. This zone was packed with a mixed support material consisting of granular bio-activated carbon (Bio-GAC) and porous material that increases the bed permeability, thus decreasing the pressure drop. Five microbial communities were acclimated and immobilized in granular activated carbon (GAC) to obtain different specialized Bio-GAC particles able to remove the micropollutants ibuprofen, naproxen, atrazine, carbaryl, and diazinon. The Bio-GAC particles were transferred to HTRs continuously run in microaerophilia at several MPs loading rates. Under these conditions, the removal efficiencies of MPs, except atrazine and carbaryl, were around 100.

Plant-mediated green synthesis of nanocomposite-based multifunctional adsorbent with antibacterial activity and high removal efficiency of micropollutants from contaminated waters

Wastewaters are contaminated with both biological and chemical pollutants that must be eliminated before reuse and/or disposal to surface waters. This paper proposes a new magnetic CuO-doped silver/polyacrylonitrile/zeolitic imidazolate framework-67 nanocomposite (M-CuO@Ag/PAN/ZIF-67) that has multifunctional behavior for removing acetaminophen (ACT) and paraquat (PQ) residuals from contaminated water while also acting as an antibacterial agent. The antibacterial agent of as-prepared nanocomposite on Gram-positive bacteria, Staphylococcus-aureus (S. aureus), and Bacillus subtilis (B. subtilis), and also Gram-negative bacteria Escherichia coli (E. coli) were studied. To minimize the use of harmful chemicals and solvents, Fe3O4, Ag, and CuO nanoparticles were prepared through plant-mediated green synthesis by renewable, and non-toxic aqueous extracts of aloe vera plant, mulberry leaves, and Gundelia tournefortii L, respectively. The adsorption results showed that the nanocomposite could remove 99.41 ± 2.21 % of the ACT and 99.23 ± 1.83 % of the PQ from the contaminated water. The Langmuir maximum adsorption capacity of ACT and PQ by nanocomposite was calculated as 971.6 and 1143.7 mg g−1, respectively, which surpasses that of most nanocomposite-based adsorbents. Also, the adsorption kinetic data were well described with the pseudo-second-order model and the adsorption thermodynamic results showed the adsorption process was endothermic and spontaneous in nature. The antibacterial properties of nanocomposite were studied by pour plate and disk diffusion methods. It was concluded that bacterial suppression by the nanocomposite was higher in the Gram-positive bacteria than in the Gram-negative bacterium. The antibacterial results also showed that the collective antibacterial effects of the nanocomposite are stronger than its components and copper oxide-doped has also strengthened the antibacterial properties. In addition, the nanocomposite could be easily regenerated by washing with methanol, and chlorination method. Finally, the adsorption efficiency and antibacterial behavior of nanocomposite remained above 80 % and 90 % after six reuse cycles, respectively.

Performance evaluation of ceramic membrane bioreactor: effect of operational parameters on micropollutant removal and membrane fouling.

This paper presents the removal of nine potential endocrine disruptors including pesticides, pharmaceuticals and industrial chemicals using a submerged membrane bioreactor (MBR) system. Two lab-scale submerged MBRs having ceramic membranes were operated at three different sludge retention times (SRT: 15, 45, 90days) and two hydraulic retention times (HRT: 12, 6h) and the effects of SRT and HRT on both micropollutant removal and membrane fouling were investigated. While the effect of SRT and HRT change was observed on the removal of atrazine, fluoxetine, penconazole, no significant change was detected for the other micropollutants studied. It was determined that physicochemical properties such as distribution coefficient (LogD) and hydrophobicity of micropollutants are also effective on the removal efficiency of micropollutants. High removal efficiencies ([Formula: see text] 97.5%) were observed for hydrophobic pollutants (logD > 3.2) except for penconazole (72.1%) and for hydrophilic pollutants (logD < 3.2) except for atrazine (42.5%). Membrane fouling was significantly affected by different operational parameters applied, with the slowest fouling occurring at 45days of SRT and 12h of HRT. However, micropollutant addition did not have a significant effect on membrane fouling. It has been shown that the simultaneous and effective treatment performance for micropollutants makes the membrane bioreactor system a promising wastewater treatment process.

A General Strategy for Kilogram-Scale Preparation of Highly Crystal-line Covalent Triazine Frameworks.

Scalable and eco-friendly synthesis of crystalline porous covalent triazine frameworks (CTFs) is essential to realize their broad industrial applications but remains a great challenge, which requires the fundamental understanding of the two-dimensional polymerization mechanism. Herein, we report a universal polyphosphoric acid (H6 P4 O13 )-catalyzed nitrile trimerization route to synthesize a series of highly crystalline CTFs with high specific surface areas. This new strategy enables the cost-effective large-scale fabrication of crystalline CTFs at kilogram level for the first time. Through density functional theory calculation and detailed controlled experiments, we reveal that the polyphosphate acid show much higher catalytic activity for trimerization reaction than its analogues such as P2 O5 and H3 PO4 . Furthermore, the crystalline CTFs with regular porosity and abundant triazine groups exhibit ultrahigh removal efficiency of micropollutants, indicating its great potential in environment remediation.

A General Strategy for Kilogram‐Scale Preparation of Highly Crystalline Covalent Triazine Frameworks

AbstractScalable and eco‐friendly synthesis of crystalline porous covalent triazine frameworks (CTFs) is essential to realize their broad industrial applications but remains a great challenge, which requires the fundamental understanding of the two‐dimensional polymerization mechanism. Herein, we report a universal polyphosphoric acid (H6P4O13)‐catalyzed nitrile trimerization route to synthesize a series of highly crystalline CTFs with high specific surface areas. This new strategy enables the cost‐effective large‐scale fabrication of crystalline CTFs at kilogram level for the first time. Through density functional theory calculation and detailed controlled experiments, we reveal that the polyphosphate acid show much higher catalytic activity for trimerization reaction than its analogues such as P2O5and H3PO4. Furthermore, the crystalline CTFs with regular porosity and abundant triazine groups exhibit ultrahigh removal efficiency of micropollutants, indicating its great potential in environment remediation.

A framework to determine the optimum contact time and organic micropollutant removal efficiency of the ozone process applied in the context of Cape Flats Managed Aquifer Recharge Water Reclamation Plant

Final wastewater treatment plant effluent is widely recognised as a hazardous water source for human consumption as it may contain organic micropollutants and pathogens. The advanced processes required to adequately remove them are costly, and consequently, it is crucial to investigate how the associated costs can be optimised. One of the key treatment steps in the treatment train of the Cape Flats Managed Aquifer Recharge (MAR) water reclamation plant (WRP) is the advanced ozonation (O3) treatment process. The O3 process was assessed using the T10 and CSTR methods. The O3/TOC dose ratio was used as the main parameter to compare and relate various O3 treatment objectives and assessment methods. Furthermore, an O3 contact time optimisation was performed on the Cape Flats O3 process using capital and operation and maintenance (O&M) costing models, as well as process performance regression models. The optimum contact time, in terms of cost for 2–4 Log virus inactivation by ozone and 1–3 Log giardia inactivation by ozone, was determined to be between 5 and 7 min by the CSTR method, and 5 min by the T10 method. The optimum contact time, in terms of cost for 1–3 log inactivation of cryptosporidium by ozone, was determined to be between 8 and 18 min by the CSTR method, and between 6 and 13 min by the T10 method, depending on the treatment objective and O3 transfer efficiency. The O3 process of the Cape Flats MAR WRP can theoretically reduce more than 87% of the organic micropollutants in the Cape Flats Wastewater Treatment Works (WWTW) final effluent.

Micropollutants removal during high rate thermophilic and hyper-thermophilic anaerobic digestion of concentrated black water

Source separated toilet water (black water; BW) is an important alternative nutrient source for agriculture. However, reuse and recovery of nutrients from BW is limited by the presence of pollutants, such as pathogens and micropollutants. In this study, the fate of micropollutants during thermophilic and hyper-thermophilic anaerobic digestion (AD) of concentrated vacuum collected BW is assessed. A total of eight pharmaceuticals were selected and spiked with two distinct loading rates to concentrated BW treated in an Upflow Anaerobic Sludge Blanket Reactors (UASB). The removal of these micropollutants was followed by measuring concentrations in the liquid phase. It was shown that the micropollutant loading rate did not affect the removal efficiency. Irbesartan, propanol, sulfamethoxazole and trimethoprim were almost completely removed under both conditions (>95% removal). Metoprolol had 74% removal under thermophilic conditions. Caffeine showed high desorption from BW solids, whereas carbamazepine is thought to be removed by sorption to the sludge in the UASB reactor. Diclofenac removal was < 30% during both temperature conditions, which may have been caused by the lack of sludge adaptation which limits the biodegradation. There were no differences in micropollutant removal efficiencies between thermophilic and hyper-thermophilic AD of concentrated BW. Therefore, it is concluded that thermophilic AD is sufficient for safe nutrient recovery in terms of micropollutants presence.

Micropollutant transformation and toxicity: Electrochemical ozonation versus biological metabolism

Environmental water sources are constantly polluted by anthropogenic compounds, not always minimized by conventional water treatment methods to remove these compounds at the micro- and nano-range. The absolute concentrations of a suite of seven representative environmental micropollutants were compared pre- and post-treatment with both ozone and microbial biofilms, in terms of removal efficiencies and toxicity assays. Both synthetic micropollutant mixes and environmental water samples were evaluated. The study started with two representative micropollutants (carbamazepine, CBZ, and sulfamethoxazole, SMX), and broadened into a suite of pollutants, evaluating whole-sample eco-toxicological footprints. An ozone concentration of 4.24 ± 0.27 mg/L in tap water, resulted in an 87.9% and 96.5% removal of CBZ and SMX, respectively, within 1 min. Despite almost immediate removal of parent micropollutants by oxidation, endocrine disruption potential (anti-estrogenicity) of CBZ and SMX required up to 240 min of ozone treatment to show no assay effect. A broader suite of micropollutants in more complex environmental matrices showed scavenging of ozone (2.95 ± 0.17–0.25 ± 0.03 mg/L) and varying micropollutant recalcitrance to oxidation. Lower matrix pollution led to lower reduction in eco-toxicity. Microbial degradation of CBZ and SMX (56% and 70% versus 19% and 79%, respectively, in duplicate biofilms) by nutrient-limited biofilms showed less removal than ozonation, with marked variation due to the stochastic nature of biofilm sloughing. Microbial degradation of CBZ and SMX resulted in an increase of &gt;90% in both estrogenicity and Aliivibrio inhibition. The results obtained from this study address a gap in understanding the removal efficiency of micropollutants, where the removal process often receives more attention than the comparative reduction of toxicological effects. This shift from a controlled laboratory environment to real-world scenarios also provided comparative insights into the removal of micropollutants and the eco-toxicity of the transformation by-products of each process.

Removal of micropollutants from municipal wastewater by membrane bioreactors: Conventional membrane versus dynamic membrane

In this study, fate of micropollutants was investigated in a membrane bioreactor (MBR) having dynamic membrane (DM) and ultrafiltration (UF) membrane for the treatment of raw municipal wastewater. Removal efficiencies of different micropollutants including sulfamethoxazole, ciprofloxacin, trimethoprim, caffeine and acetaminophen were assessed. A commercial hollow fiber UF membrane was used in parallel with a DM that was formed on a low-cost hollow fiber support material, made of polyester. MBR was operated at a flux of 10 L/m2·h. High total suspended solids (>99%) and chemical oxygen demand (>91%) removal efficiencies were achieved with each membrane. Besides, high removal efficiencies of micropollutants (>68.3->99.7%) were achieved. Morphological analyses were conducted for each membrane in order to get insight to the cake (dynamic) layer that was accumulated on the membrane. DM technology provides an effective alternative to the conventional membrane systems for micropollutant removal from municipal wastewater.

Removal of organic micropollutants in the biological units of a Swedish wastewater treatment plant

The present study investigates the presence and removal of target organic micropollutants in a large Swedish wastewater treatment plant designed for nutrient removal including activated sludge, trickling filters, nitrifying moving bed biofilm reactors (MBBRs) and post-denitrifying MBBRs. A total of 28 organic micropollutants were analysed, at concentrations ranging from few ng/L to µg/L, in the influent and effluent of the different biological reactors in two sampling campaigns. The observed micropollutant removal efficiencies of the wastewater treatment plant varied from insignificant (< 20%) to high (> 90%) between compounds. The activated sludge reactor, being the first in line, contributed to most of the removal from the water phase. Additional removal of a few compounds was observed in the biofilm units, but most of the persistent compounds remained stable through all biological treatments.