Sulfamethoxazole Degradation Efficiency Research Articles

Effect of substrate concentration on sulfamethoxazole wastewater treatment by osmotic microbial fuel cell: Insight into operational efficiency, dynamic changes of membrane fouling and microbial response.

To solve the problems of antibiotic pollution, water resources and energy shortage, an osmotic microbial fuel cell (OsMFC) was adopted innovatively to treat antibiotic wastewater containing sulfamethoxazole (SMX), and achieved SMX removal, water production and electricity generation. Substrate concentration was a key factor affecting the performances of OsMFC, which was often ignored by researchers. This study explored the effect of substrate concentration on system performances, clarified the dynamic changes of membrane fouling under different substrate concentrations, and further revealed the response of microbial communities. The results showed that the stable removal efficiency of SMX exceeded 98.8 % due to the efficient interception of forward osmosis (FO) membrane. Compared with the 1.0 g/L NaAc system, the SMX degradation efficiency and maximum output voltage in the 2.0 g/L NaAc system were only increased by 3.9 % and 6.3 %, respectively. However, the initial water flux decreased by 30.1 % in the 7th cycle due to more serious FO membrane fouling. In addition, there were significant differences in the dynamic formation process of FO membrane fouling. Higher substrate concentration increased the relative abundance of Desulfobacterota and Geobacter. Functional prediction analysis showed that increasing substrate concentration promoted carbohydrate metabolism pathways and relative abundance of sulfur respiration functional groups, thereby improving COD and SMX removal rates. However, the biosynthesis of other secondary metabolites was significantly improved, resulting in increased contents of EPS and SMP, which aggravated membrane pollution. Overall, the system performed better when the substrate concentration was 1.0 g/L. This study would provide certain guidance for the performance optimization and membrane fouling mitigation of OsMFC, thereby promoting its practical application in antibiotic wastewater treatment.

Weak magnetic field for enhanced degradation of sulfamethoxazole by the CoFe2O4/PAA system: Insights into performance and mechanism

In this work, a novel approach coupling a heterogeneous weak magnetic field (WMF) with the CoFe2O4/peroxyacetic acid (PAA) system was employed to enhance the degradation of sulfamethoxazole (SMX). Under the optimized conditions of 50 mT WMF, 0.1 g/L CoFe2O4, 0.2 mM PAA, and initial pH 6.0, a complete degradation of 10 μM SMX was achieved in 25 min, exhibiting a high synergistic coefficient of 1.61. This result indicates a significant synergistic effect among WMF, CoFe2O4, and PAA in effectively degrading SMX. The introduction of WMF did not alter the pH application range of the CoFe2O4/PAA system. Furthermore, the degradation efficiency of SMX by the CoFe2O4/PAA/WMF system was significantly reduced in the presence of humic acid (HA) and bicarbonate ions (HCO3−), while chloride ions (Cl−) exhibited a minor inhibitory effect. Quenching experiments and electron paramagnetic resonance (EPR) analysis reveal that WMF did not alter the types of reactive oxygen species (ROS) generated in the CoFe2O4/PAA system. The degradation of SMX in the CoFe2O4/PAA/WMF system involved both radical (CH3C(O)O∙ and CH3C(O)OO∙) and non-radical (1O2) oxidation pathways, driven by the redox cycling between ≡Co2+/≡Co3+ and PAA, as well as the rapid adsorption and transformation of oxygen (O2) at oxygen vacancies (OV), respectively. The presence of WMF enhanced the utilization of PAA by CoFe2O4 by improving the convection and mass transport in the solution, facilitating the formation of superoxide anion (O2∙−) and supplemented lattice oxygen (O2−) through the directional migration of paramagnetic O2 towards the CoFe2O4 surface, thus significantly promoting ROS formation. Additionally, the degradation pathways of SMX in the CoFe2O4/PAA/WMF system were proposed based on density functional theory (DFT) calculations and the detected transformation products (TPs). The toxicity of SMX was effectively reduced, as verified by predictions from the Ecological Structure-Activity Relationship Model (ECOSAR) procedure. The excellent catalytic performance, reusability, and effective degradation of various organic pollutants demonstrated by the CoFe2O4/PAA/WMF system suggest its potential as a promising strategy for water treatment.

Peroxymonosulfate Activation by Fe@N Co-Doped Biochar for the Degradation of Sulfamethoxazole: The Key Role of Pyrrolic N

In this study, Fe, N co-doped biochar (Fe@N co-doped BC) was synthesized by the carbonization–pyrolysis method and used as a carbocatalyst to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) removal. In the Fe@N co-doped BC/PMS system, the degradation efficiency of SMX (10.0 mg·L−1) was 90.2% within 40 min under optimal conditions. Radical quenching experiments and electron spin resonance (ESR) analysis suggested that sulfate radicals (SO4•−), hydroxyl radicals (•OH), and singlet oxygen (1O2) participated in the degradation process. After the reaction, the proportion of pyrrolic N decreased from 57.9% to 27.1%. Pyrrolic N served as an active site to break the inert carbon network structure and promote the generation of reactive oxygen species (ROS). In addition, pyrrolic N showed a stronger interaction with PMS and significantly reduced the activation energy required for the reaction (∆G = 23.54 kcal/mol). The utilization potentiality of Fe@N co-doped BC was systematically evaluated in terms of its reusability and selectivity to organics. Finally, the intermediates of SMX were also detected.

Assessment of photocatalytic activities of layered double hydroxide@petrochemical sludge biochar for sulfamethoxazole degradation

Layered double hydroxides (LDHs) as one of the popular photocatalysts have the drawbacks of compact structural arrangement and pronounced nano-particle clustering, which affect their photocatalytic performance for the degradation of organic pollutants from water or wastewater. Using biochar as a substrate matrix to support LDHs may be a good way to improve the photocatalytic performance of LDHs by avoiding agglomeration effect, promoting the separation of photogenerated electrons from holes for organics degradation. In this study, the composite of CoFe-LDH and petrochemical sludge biochar (CoFe-LDH@PBC) was fabricated and applied for the first time as photocatalyst for catalytic degradation of sulfamethoxazole (SMX). Results showed CoFe-LDH@PBC800/UV system exhibited excellent photocatalytic activity on SMX degradation than single CoFe-LDH/UV, PBC800/UV, or PBC105/UV system under various reaction conditions (photocatalyst dosage, pH, system speed, and SMX concentration). 100 % of SMX degradation efficiency and 88.98 % mineralization efficiency could be achieved in CoFe-LDH@PBC800/UV system within 100 min. The corresponded pseudo-first-order kinetic rate constant (kobs) of SMX degradation in CoFe-LDH@PBC800/UV system was 0.032 min−1, which was 3.20, 8.00, and 2.46 times higher than that of CoFe-LDH/UV, PBC800/UV, and PBC105/UV, respectively. In photocatalytic process, OH, O2−, and h+ participated in SMX degradation, among which h+ or OH played a major role. The good photocatalytic performance of CoFe-LDH@PBC800 composite was related to its excellent physiochemical properties, such as lower band gap (2.39 eV), high graphitization degree, and high conductivity, enabling efficient e−/h+ separation of photocatalyst for SMX degradation. Four distinct pathways of SMX degradation were proposed based on DFT theoretical calculations and byproducts of SMX degradation identified by LC-MS. Additionally, results from recycling tests suggested CoFe-LDH@PBC800 composite possessed a favorable reusability and could be applied for photocatalytic degradation of SMX at least 3 times. Over all, CoFe-LDH@PBC800 composite was proved to be an efficient photocatalyst for antibiotic degradation in water or wastewater and the reuse of petrochemical wastewater sludge was expected to realize the concept of resourceful and high-value utilization of waste biomass.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) bioanodes in Co-doped modified microbial fuel cell promote sulfamethoxine degradation with high enrichment of electroactive bacteria and extracellular electron transfer

Microbial fuel cell (MFC) is a new renewable energy technology, which has a wide range of applications. In this paper, the refractory organic matter sulfamethoxazole (SMX) was degraded by MFC technology, and the electricity generation performance was analyzed in detail. Since Ni and Fe ions can promote electron transfer, the presence of S ions can enhance the biocompatibility of the material, in this study, nano-ferro nickel sulfide (NiFe2S4) was prepared by hydrothermal method, and co-doped with ferro oxide (Fe3O4) nanoparticles to modify the poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) hydrogel served as the bioanode of MFC. Through high throughput results, we found the enriched electro producing bacteria Desulfuromonas and Fe-S cluster oxidoreductase, proving that bimetallic sulfides have good synergistic effect with metal oxides, which can provide more active sites and accelerate the EET process. The maximum power density obtained as a bioanode in MFC was 3.67 W/m3. During degradation of SMX, the maximum power density was 2.39 W/m3. At the same time, the degradation efficiency of SMX reached 93.78 %, and the chemical oxygen demand (COD) removal rate was 32.52 %. This provides a valuable reference for the degradation of refractory organic compounds such as antibiotic SMX, and also provides multi-dimensional thinking for renewable energy technologies.

Insights to the cooperation of double-working potential electroactive biofilm for performance of sulfamethoxazole removal: ARG fate and microorganism communities

Bioelectrochemical systems (BESs) have shown great potential in enhancing sulfamethoxazole (SMX) removal. However, electroactive biofilms (EBs) constructed with single potentials struggle due to limited biocatalytic activity, hindering deep SMX degradation. Here, we constructed a double-working potential BES (BES-D) to investigate its ability to eliminate SMX and reduce the levels of corresponding antibiotic resistance genes (ARGs). The preferable electrochemical activity of EB in BES-D was confirmed by electrochemical characterization, EPS analysis, physical structure, viability of the biofilm, and cytochrome content. BES-D exhibited a notably greater SMX removal efficiency (94.2 %) than did the single-working potential BES (BES-S) and the open-circuit group (OC). Degradation pathway analysis revealed that the cooperative EB could accelerate the in-depth removal of SMX. Moreover, EB interaction in BES-D decreased the relative abundance of ARGs in biofilms compared to that in BES-S, although the absolute number of ARG copies increased in BES-D effluents. Compared to those in BES-S and OC, more complex cross-niche microbial associations in the EB of BES-D were observed by network analysis of the bacterial community and ARG hosts, enhancing the degradation efficiency of SMX. In conclusion, BES-D has significant potential for SMX removal and the enhancement of EB activity. Nonetheless, the risk of ARG dissemination in effluent remains a concern.

LaCoO3@Fe3O4 as peroxymonosulfate activator derived from spent lithium battery cathode materials for degradation of sulfamethoxazole in water

To reduce the various hazards of SMX to aquatic ecosystems, in this study, magnetically separable LaCoO3@Fe3O4 catalysts for the degradation of sulfamethoxazole (SMX) in water by activated peroxymonosulfate (PMS) were successfully prepared by using cobalt oxalate recovered from spent batteries using sol–gel, hydrothermal, and high-temperature calcination methods. The main factors influencing the reaction and the effect of coexisting ions on the degradation efficiency of SMX were investigated. The results showed that under optimal conditions ([SMX] = 30 mg, [LaCoO3@Fe3O4] = 10 mg/L, [PMS] = 30 mg/L, pH (initial) = 7.02), the LaCoO3@Fe3O4/PMS system degraded SMX up to 93 % in 15 min. The degradation of SMX in the LaCoO3@Fe3O4/PMS system was shown to be achieved by a combination of radical (SO4•-/•OH/•O2–) and non-radical (1O2) pathways by quenching experiments and electron paramagnetic resonance spectroscopy (EPR) analysis. Then, three possible degradation pathways were proposed using LC-MS, and Ecological Constitutive Relationship (ECOSAR) analysis showed that the toxicity of the intermediate products was all lower than that of SMX, indicating that the system is feasible for SMX degradation. This study provides a new idea for activating PMS for the degradation of antibiotics in water by preparing catalysts using precious metals from recycled batteries.

Degradation mechanism and decomposition of sulfamethoxazole aqueous solution with persulfate activated by dielectric barrier discharge

ABSTRACT The present study focused on the degradation of sulfamethoxazole (SMX) aqueous solution and the toxicity of processing aqueous by the dielectric barrier discharge (DBD) activated persulfate (PS). The effects of input voltage, input frequency, duty cycle, and PS dosage ratio on the SMX degradation efficiency were measured. Based on the results of the Response Surface Methodology (RSM), SMX degradation efficiency reached 83.21% which is 10.54% higher than that without PS, and the kinetic constant was 0.067 min−1 in 30 min when the input voltage at 204 V (input power at 110.6 W), the input frequency at 186 Hz, the duty cycle at 63%, and the PS dosage ratio at 5.1:1. The addition of PS can produce more active particles reached 1.756 mg/L (O3), 0.118 mg/L (H2O2), 0.154 mmol/L (·OH) in 30 min. Furthermore, the DBD plasma system effectively activated an optimal amount of PS, leading to improved removal efficiency of COD, and TOC to 30.21% and 47.21%, respectively. Subsequently, eight primary by-products were pinpointed, alongside the observation of three distinct pathways of transformation. Predictions from the ECOSAR software indicated that most of the degradation intermediates were less toxic than SMX. The biological toxicity experiments elucidated that the treatment with the DBD/PS system effectively reduced the mortality of zebrafish larvae caused by SMX from 100% to 20.13% and improved the hatching rate from 55.69% to 80.86%. In particular, it is important to note that the degradation intermediates exhibit teratogenic effects on zebrafish larvae.

Impact of Condition Variations on Bioelectrochemical System Performance: An Experimental Investigation of Sulfamethoxazole Degradation.

Bioelectrochemical systems (BESs) are an innovative technology for the efficient degradation of antibiotics. Shewanella oneidensis (S. oneidensis) MR-1 plays a pivotal role in degrading sulfamethoxazole (SMX) in BESs. Our study investigated the effect of BES conditions on SMX degradation, focusing on microbial activity. The results revealed that BESs operating with a 0.05 M electrolyte concentration and 2 mA/cm2 current density outperformed electrolysis cells (ECs). Additionally, higher electrolyte concentrations and elevated current density reduced SMX degradation efficiency. The presence of nutrients had minimal effect on the growth of S. oneidensis MR-1 in BESs; it indicates that S. oneidensis MR-1 can degrade SMX without nutrients in a short period of time. We also highlighted the significance of mass transfer between the cathode and anode. Limiting mass transfer at a 10 cm electrode distance enhanced S. oneidensis MR-1 activity and BES performance. In summary, this study reveals the complex interaction of factors affecting the efficiency of BES degradation of antibiotics and provides support for environmental pollution control.

Interactive effects of urine components and treatment conditions on antibiotic degradation of combined system integrating thermally activated peroxydisulfate and membrane distillation using machine learning

The antibiotic degradation in urine is gaining focus as it’s essential for resource recovery. Complex organic and inorganic substances in urine impact degradation efficiency through their involvement in radical-type chain reactions. In this study, more than 95 % of sulfamethoxazole (SMX) in urine was successfully degraded in both concurrent and sequential modes of a combined system integrating thermally activated peroxydisulfate and membrane distillation (TAP-MD), previously shown to be effective for resource recovery. Three algorithms, including random forest (RF), XGBoost, and support vector machine (SVM), were applied to model the impact of urine components and treatment conditions on SMX degradation. The XGBoot and RF models, fine-tuned by Bayesian optimization, are accurate and credible in both prediction and interpretation (R2 > 0.90). The models suggest that the improvement of SMX degradation by the MD process is due to PDS enrichment, with high PDS concentrations significantly promoting SMX degradation. Urea and HCO3− are the key factors impacting SMX degradation efficiency, followed by temperature, PDS, Cl−, and NH4+. Additionally, strong interaction effects between urine components were found on SMX degradation, contrasting with results from individual ions that were present in isolation. At high urea concentration (>100 mM), increasing concentrations of Cl−, NH4+, and HCO3− significantly inhibited SMX degradation. As the second key factor on SMX degradation, HCO3− can react with S2O82− without producing free radicals, resulting in a reduction in its yield. Furthermore, in the presence of high concentrations of HCO3−, the Cl− and NH4+ negatively affect the kobs of SMX degradation. The HCO3− competes with SMX for Cl to produce the weak oxidant CO3∙−, which reacts quickly with NH2∙ without producing other free radicals, causing a loss of free radicals.

Enhanced biodegradation of sulfamethoxazole by pyrogenic carbon derived from aquacultural waste sludge

Sulfamethoxazole (SMX) is a widely utilized antibiotic that exhibits a broad spectrum of antibacterial activity, but its inadvertent release into the environment poses a significant threat to human society. The inefficacy of SMX degradation in microbial pipelines constantly challenges the regulation of antibiotics, making it a pressing and compelling concern. Former research has demonstrated the enhancement of the waste sludge-derived materials on SMX biodegradation, but the impact of these materials on microbial behavior remains unclear. In this study, two pyrogenic carbon materials (FBC and RBC) were prepared from aquacultural waste sludge and its downstream river sediment, respectively, to collaborate with SMX degrading species, Alcaligenes sp., for highly efficient removal of SMX. The cells of Alcaligenes sp. successfully colonized onto the biocompatible surface of the materials, and this hybrid structure nearly doubled the SMX degradation efficiency of the group without the carbon materials. The transcriptome analysis revealed that the existence of carbon materials significantly upregulated the expression of SMX degrading-related genes, including metCF and paaCIK, which led to bond breaking and benzene ring breakdown for the degradation of sulfamethoxazole. This work provides new insights into the mechanisms and environmental significance of SMX degradation by microbial immobilization onto waste-derived carbon-rich materials.

New insights into bioaugmented removal of sulfamethoxazole in sediment microcosms: degradation efficiency, ecological risk and microbial mechanisms

BackgroundBioaugmentation has the potential to enhance the ability of ecological technology to treat sulfonamide-containing wastewater, but the low viability of the exogenous degraders limits their practical application. Understanding the mechanism is important to enhance and optimize performance of the bioaugmentation, which requires a multifaceted analysis of the microbial communities. Here, DNA-stable isotope probing (DNA-SIP) and metagenomic analysis were conducted to decipher the bioaugmentation mechanisms in stabilization pond sediment microcosms inoculated with sulfamethoxazole (SMX)-degrading bacteria (Pseudomonas sp. M2 or Paenarthrobacter sp. R1).ResultsThe bioaugmentation with both strains M2 and R1, especially strain R1, significantly improved the biodegradation rate of SMX, and its biodegradation capacity was sustainable within a certain cycle (subjected to three repeated SMX additions). The removal strategy using exogenous degrading bacteria also significantly abated the accumulation and transmission risk of antibiotic resistance genes (ARGs). Strain M2 inoculation significantly lowered bacterial diversity and altered the sediment bacterial community, while strain R1 inoculation had a slight effect on the bacterial community and was closely associated with indigenous microorganisms. Paenarthrobacter was identified as the primary SMX-assimilating bacteria in both bioaugmentation systems based on DNA-SIP analysis. Combining genomic information with pure culture evidence, strain R1 enhanced SMX removal by directly participating in SMX degradation, while strain M2 did it by both participating in SMX degradation and stimulating SMX-degrading activity of indigenous microorganisms (Paenarthrobacter) in the community.ConclusionsOur findings demonstrate that bioaugmentation using SMX-degrading bacteria was a feasible strategy for SMX clean-up in terms of the degradation efficiency of SMX, the risk of ARG transmission, as well as the impact on the bacterial community, and the advantage of bioaugmentation with Paenarthrobacter sp. R1 was also highlighted.8sNhd6qoUNMdHWMUGzd-tFVideo

CoO quantum dots anchored on P-doped carbon nitride improves peroxymonosulfate activation to degrade sulfamethoxazole

The development of highly dispersed and ultra-small size cobalt-loaded catalysts is crucial for achieving efficient and low secondary pollution in peroxymonosulfate (PMS) activation processes. Herein, a phosphorus-doped carbon nitride (PCN) loaded with CoO quantum dot catalyst (Co80-PCN) was derived from the mixture of BINAP-CoCl2 complex (BINAP = 1,1′-binaphthyl-2,2′-diphosphine) and carbon nitride (CN). Structural studies revealed that cobalt oxide quantum dots with an average diameter of 9.99 nm were evenly and securely attached to the PCN substrate. The optimal Co80-PCN/PMS system demonstrated an almost 100% degradation efficiency of sulfamethoxazole (SMX, 10 mg/L) within 15 min, with a reaction rate constant of 0.3341 min−1, which was 30.1 times higher than that of the CN/PMS system. This outstanding degradation performance could be primarily attributed to the enhanced catalytic activity of CoO quantum dots and the improved electronic structure resulting from P-doped CN. This work offers valuable insights for the future design of carbon material loaded quantum dot catalysts.

Porous pie-like nitrogen-doped biochar as a metal-free peroxymonosulfate activator for sulfamethoxazole degradation: Performance, DFT calculation and mechanism

Design and development of low-cost, high-efficient, metal-free persulfate heterogeneous catalysts was a hot research topic. Herein, porous pie-like nitrogen-doped biochar (NBC) was prepared by one step high temperature pyrolysis of rape straw, urea and ZnCl2 mixture, and applied for peroxymonosulfate (PMS) activation toward sulfamethoxazole (SMX) degradation. Among these as-prepared catalysts, the NBC2.0 sample presented the best catalytic activity, with the 99.8 % SMX degradation efficiency in 5 mins and the 81.7 % total organic carbon (TOC) removal rate in 30 mins. Additionally, it could realize an excellent SMX degradation in the wide pH range of 3.0 to 9.0, and possessed the high degradation efficiency in presence of various organic pollutants or in real water environments, indicating its good pH adaptability, universality and practicality. Mechanistic investigations disclosed that the NBC2.0/PMS/SMX system involved both radical and non-radical degradation pathways, with singlet oxygen (1O2) and the direct electron transfer mechanism being the main contributors. The main active reaction sites of NBC were graphitic N, pyridinic N and C = O group, as corroborated by density functional theory (DFT) calculation and X-ray photoelectron spectroscopy (XPS) measurement. The possible SMX breakdown routes were determined by intermediate identification. This work provides a promising metal-free persulfate catalyst for environment remediation.

2D ZIF-L arrays supported on zinc foam to activate peroxymonosulfate for degrading sulfamethoxazole through both radical and non-radical pathways

The development of easy recovery and high efficiency heterogeneous catalysts for activating peroxymonosulfate (PMS) is of great significance in the treatment of environmental pollutants. In this study, we successfully immobilized 2D ZIF-L arrays on a zinc foam (ZF) through a room temperature deposition method, creating a self-supporting ZIF-L/ZF catalyst. The ZIF-L/ZF exhibited high catalytic efficiency and durable recyclability for activating PMS to degrade sulfamethoxazole (SMX). Within 10 min, a 97 % degradation efficiency of SMX was achieved, which could be attributed to the unique integrated architecture and Co2+/Co3+ redox cycle of the catalyst. Furthermore, the effects of various environmental factors on catalytic activity were evaluated. By identifying the reactive species, both radical and non-radical oxidation process occurred during PMS activation. Additionally, the ZIF-L/ZF could be easy reused over 10 cycles, demonstrating a practical application value. We also proposed a possible degradation pathway for SMX based on Fukui index calculations and HPLC-MS. Our findings provide valuable insights into the construction of self-supporting catalyst for pollutant removal.

CuFeS2 supported on dendritic mesoporous silica-titania for persulfate-assisted degradation of sulfamethoxazole under visible light

Sulfamethoxazole (SMX) is a prevalent sulfonamide antibiotic found in the environment, and it has a variety of detrimental effects on environmental sustainability and water safety. Recently, the combination of photocatalysis and sulfate radical-based advanced oxidation processes (SR-AOPs) has attracted a lot of interest as a viable technique for degradation of refractory pollutants. In this study, a visible light active CuFeS2 supported on dendritic mesoporous silica-titania (CuFeS2-DMST) photocatalyst was synthesized to improve the ability of TiO2 to activate persulfate (PS) by introducing CuFeS2 (Fe2+/Fe3+, Cu+/Cu2+ redox cycles). The CuFeS2-DMST/PS/Vis system demonstrated superior SMX degradation efficiency (88.9%, 0.0146 min−1) than TiO2 because of reduced e-/h+ recombination, excellent charge separation and mobility, and a greater surface area than TiO2. Furthermore, after four consecutive photocatalytic cycles, the system demonstrated moderate stability. From chemical quenching tests, O2●-, h+, 1O2, SO4●- and ●OH were found to be the main reactive oxidizing species. The formed intermediates during the degradation process were identified, and degradation mechanisms were proposed. This study proposes a viable technique for activating PS using a low-cost, stable, and high-surface-area TiO2-based photocatalyst, and this concept can be applied to design photocatalysts for water treatment.

Metabolic engineering of Paracoccus denitrificans for dual degradation of sulfamethoxazole and ammonia nitrogen.

Sulfamethoxazole (SMX), as one of the most widely used sulfonamide antibiotics, has been frequently detected in the aqueous environment, posing potential risks to the environment and human health. Although microbial degradation methods have been widely applied, some issues remain, including low degradation efficiency and poor environmental adaptability. In this regard, constructing efficient degrading bacteria by metabolic engineering is an ideal solution to these challenges. In this study, we used Paracoccus denitrificans DYTN-1, a superior nitrogen removal environment strain, as chassis to construct an SMX degradation pathway, obtaining a new bacteria for simultaneous degradation of SMX and removal of ammonia nitrogen. In doing this, we first identified and characterized four native promoters of P. denitrificans DYTN-1 with gradient strength to control the expression of the SMX degradation pathway. After degradation pathway expression level optimization and FMN reductase optimization, SMX degradation efficiency was significantly improved. The constructed P. d-pIAB4-PCS-sutR strain exhibited superior co-degradation of SMX and ammonia nitrogen contaminants with degradation rates of 44% and 71%, respectively. This study could pave the way for SMX degradation engineered strain design and evolution of environmental bioremediation. IMPORTANCE The abuse of sulfamethoxazole (SMX) had led to an increased accumulation in the environment, resulting in the disruption of the structure of microbial communities, further disrupting the bio-degradation process of other pollutants, such as ammonia nitrogen. To solve this challenge, we first identified and characterized four native promoters of Paracoccus denitrificans DYTN-1 with gradient strength to control the expression of the SMX degradation pathway. Then SMX degradation efficiency was significantly improved with degradation pathway expression level optimization and FMN reductase optimization. Finally, the superior nitrogen removal environment strain, P. denitrificans DYTN-1, obtained an SMX degradation function. This pioneering study of metabolic engineering to enhance the SMX degradation in microorganisms could pave the way for designing the engineered strains of SMX and nitrogen co-degradation and the environmental bioremediation.

Bifunctional Solar Evaporator with Co/N-Doped Graphene Oxide for Synergistic Steam Generation and Organic Pollutant Degradation.

Solar-driven interfacial steam generation (SISG) is a promising technology for alleviating freshwater shortage. However, when the SISG technology is applied to wastewater treatment, the contaminant would be enriched in residual bulk water. Herein, a dual-functional evaporator was constructed via tactfully decorating Co/N-doped graphene oxide (GO) on melamine foam (MF), which can simultaneously achieve efficient vapor production and source water purification. N-doped carbon nanotubes (NCNTs) endowed evaporators with powerful light absorption and water transport performance, guaranteeing an evaporation rate of 2.02 kg m-2 h-1 under 1 sun irradiation. Meanwhile, the catalytic activity of the carbon layer was adjusted by the N dopant and embedded Co particles, providing abundant active sites to activate peroxymonosulfate (PMS). When treating the solution containing sulfamethoxazole (SMX), no SMX residues were detected in the remaining bulk water (up to 100% SMX degradation efficiency within 60 min), demonstrating that reactive oxygen species (ROS) were generated to attack SMX in the source water. The bifunctional evaporator successfully combined SISG and advanced oxidation processes (AOPs), providing an ingenious strategy for solving the problem of wastewater enrichment during SISG.

Efficient sulfamethoxazole degradation via boosting nonradical-based peroxymonosulfate activation by biochar supported Co-Ni bimetal oxide

Nonradical-based peroxymonosulfate (PMS) activation has recently caught increasing attention due to its less susceptible to environmental interference in the complex water matrix, but the performance of activators still requires further development for efficient pollutants degradation in wastewater treatment. Herein, a novel Co-Ni bimetal oxide loaded biochar was fabricated to boost nonradical PMS activation for enhancing sulfamethoxazole (SMX) degradation. According to the results, the as-obtained catalyst exhibited excellent SMX degradation efficiency of 96.2% within 30 min through complete nonradical oxidation pathway (including both 1O2 and mediated electron transfer). Co was confirmed to be the active sites to generate 1O2 dominated nonradical pathway. The biochar acted as the porous material to achieve the electron transfer oxidation process, as well as Ni ensured sufficient electron transfer rate and bound Co active sites to prevent the leaching of metal ions. Meanwhile, the prepared Co-Ni bimetal oxide loaded biochar possessed a remarkable catalytic degradation durability in the complex water environment conditions and showed universality for various organic contaminants. This study offers a valuable clue on the rational design of novel catalyst to induce the nonradical pathway-based persulfate activation.

Electrochemical activation of periodate: A novel strategy for the degradation of sulfamethoxazole with wide applicable pH range

Herein, this work investigated a novel strategy utilizing electrochemical activation of periodate (EC/PI) for effective degradation of sulfamethoxazole (SMX) with wide appliable pH range. The EC/PI system achieved 100% degradation efficiency of SMX under optimum conditions of 7.78 mA/cm2 current density, 1 mmol/L IO4− dosage, and 20 mmol/L Na2SO4 as the supporting electrolyte. Strong synergistic effect between applied electric current and IO4− activation was observed, indicating the robustness of EC/PI system. Through a series of chemical probe experiments and electron paramagnetic resonance analysis, it was revealed that EC/PI is a composite oxidation system with multiple active species, including hydroxyl radical (•OH), iodate radical (IO3•), and singlet oxygen (1O2). The production mechanisms of these active species were comprised of two routes: direct production via the electrode supplying electrons and indirect production via hydrogen peroxide (H2O2) and superoxide radical (O2•−) as intermediates. The EC/PI process was slightly affected by the coexisting substances in the water background, and cycle experiments verified its degradation stability, indicating that this EC/PI system exhibits excellent capacity for treatment of authentic wastewater. Finally, the SMX degradation intermediates and pathways were obtained using mass spectrometry analysis and Gauss theory calculations. These results indicated the establishment of EC/PI system provides an efficient and environmental-friendly strategy for treatment of emerging organic pollutants.