Removal Efficiency Of Sulfamethoxazole Research Articles

Promoting effect of plant hormone gibberellin on co-metabolism of sulfamethoxazole by microalgae Chlorella pyrenoidosa

In this study, sodium acetate (NaAC) as a co-substrate effectively promoted the metabolism of sulfamethoxazole (SMX) by microalgae Chlorella pyrenoidosa. In the cultivation supplied with 5.0 and 10.0 g L−1 NaAC, 51.1% and 61.2% SMX was removed, respectively. On this basis, the improvement effect of plant hormone gibberellin (GA3) on SMX removal by 5 g L−1 NaAC supplied as co-substrate was further investigated. The results showed that biodegradation played decisive role in the removal of SMX. As a plant hormone, GA3 effectively improved the co-metabolic removal efficiency of SMX by C. pyrenoidosa. Especially when GA3 dosage reached 10.0 and 50.0 mg L−1, C. pyrenoidosa showed a very high SMX removal rate of 83.5% and 95.3%, respectively. Transcriptome analysis showed that GA3 promoted the removal of SMX by C. pyrenoidosa was the result of the combined action of exogenous and endogenous plant hormones.

Efficient electrochemical oxidation of sulfamethoxazole by a novel reduced TiO2 nanotube arrays-based flow-through electrocatalytic membrane

The reduced TiO2 nanotube arrays (RTNA) electrode is a cost-effective anode, but its limited electrocatalytic activity is an obstacle for the application. To solve this problem, a reduced TiO2 nanotube arrays-based titanium membrane (RTNA/TM) was fabricated by a facile electrochemical method to promote the electrocatalytic performance. The one-dimensional nanostructure and reduction treatment increased the electrocatalytic capacity and reduced the energy consumption, resulting in the sulfamethoxazole (SMX) removal rate of 86.1% and electrical efficiency per order of 0.55 kWh/m3 for RTNA/TM. Compared with the batch mode, the SMX removal efficiency of the flow-through mode was significantly increased by 71%, verifying the superiority of a porous flow-through anode. The SMX degradation performances of RTNA/TM were strongly affected by the fluid velocity, current density and initial SMX concentration, except for pH. Both hydroxyl radicals and direct electron transfer were responsible for the SMX removal, while the contribution of sulfate radicals could be ignored. Furthermore, RTNA/TM displayed stable performances for five experimental cycles and showed remarkable degradation efficiencies of SMX spiked into the natural water (76.5%) and wastewater effluent (75.4%). Therefore, RTNA/TM has been proven to be a promising flow-through anode for electrochemical oxidation.

Photocatalytic removal of sulfamethoxazole using yeast biomass-derived NixP/biocarbon composites in the presence of dye sensitizer

Photocatalysis represents an environmental-benign approach for organic pollutant treatment. Herein, a photocatalytic system composed of NixP/biocarbon composite as reactive center and erythrosine B (ErB) as sensitizer was constructed for the removal of sulfamethoxazole (SMX) antibiotic under visible light irradiation. NixP/biocarbon composites were fabricated via a facile impregnation-pyrolysis approach using baker’s yeast as both phosphorus and carbon precursor. It was found that NixP with pure Ni12P5, almost pure Ni2P or mixed crystal phases could be obtained by simply adjusting Ni:P molar ratio in precursor and pyrolysis temperature. Interestingly, the variation of NixP crystal phases remarkably affected photocatalytic removal efficiency of SMX. The obtained NixP(1:4)− 900 sample with mixed phases of Ni12P5 and Ni2P displayed excellent photodegradation performance with 98.71% removal efficiency for SMX (C0 = 20 mg L−1) in ErB-sensitized photocatalytic system. Moreover, the reusability of NixP/biocarbon composite was confirmed by four consecutive runs. The slight loss of activity in recycle study could be fully recovered after thermal regeneration. Further investigation indicated that photo-generated electrons from excited ErB molecules could be transferred to NixP/biocarbon, triggering a series of reactions to form various reactive oxygen species (eg., •O2−, H2O2, •OH) for SMX degradation. The better photocatalytic activity of NixP mixed crystal phases should be ascribed to its faster electron transfer ability. Overall, this study provides useful guidance in terms of the development of transition metal phosphide and efficient photocatalytic system.

Mechanism and process of sulfamethoxazole decomposition with persulfate activated by pulse dielectric barrier discharge plasma

The present study focused on pulse dielectric barrier discharge (DBD) plasma activated persulfate (PS) for sulfamethoxazole (SMZ) degradation in water. The results showed that PS addition could enhance removal efficiency of SMZ in pulse DBD plasma system. The highest removal efficiency, kinetic constant and energy efficiency reached 93.4%, 0.084 min−1 and 0.353 g/kWh respectively with the PS dosage of 40:1 and input power of 85 W. With increase of imput power and pulse frequency, the removal efficiency of SMZ was also increased. The removal efficiency was firstly enhanced and then declined as raising duty cycle and liquid flow rate. SMZ degradation was promoted in alkaline solution conditions. Active species including ·OH, e-, ·O2–, 1O2 and ·SO- 4 play a certain role in the degradation of SMZ. The decline of O3 and enhancement of ·OH and H2O2 were found after PS addition. In process of SMZ degradation, the overall conductivity increased but pH decreased. PS addition accelerated the removal of COD and TOC. The degradation process was explored by UV–Vis spectra, three-dimensional fluorescence and LC-MS. Three degradation pathways were deduced based on the indentified intermediates. SMZ degradation in the system was considered as a toxicity-attenuation process. The water matrix including Cl-, HCO3–, SO42- and HA have some impact on SMZ degradation. This study presented that pulse DBD plasma could activate PS efficiently, which finally improved pollutant removal efficiency and energy utilization.

Performance and mechanism of SMX removal in an electrolysis-integrated tidal flow constructed wetland at low temperature

Constructed wetlands are a well-established technique to degrade wastewater contained antibiotics. And its removal at low temperature (<15 °C) has baffled researchers and engineers for decades. Electrochemical process has been increasingly valued as a promising approach to enhance antibiotics removal by both electrocatalytic oxidation–reduction and electrocoagulation. A pilot study was conducted using an electrolysis-integrated tidal flow constructed wetland (E-TFCW) to intensity sulfamethoxazole (SMX) under 4, 8 and 12℃ temperature regimes. E-TFCW have shown the better SMX removal efficiency (16.38% ∼ 31.45%) at low temperature, which was nearly 14.10% ∼ 25.31% higher than that of TFCW. It was no significant difference between 4℃, 8℃ and 12℃ in E-TFCW, which was attributed to electrocatalysis of iron electrode. Temperature had no effect on the degradation path of SMX, where SMX was removed with hydroxylation, nitration and S-N hydrolysis. Proteobacteria contributed to higher SMX removal efficiency at low temperature. The response speed of microorganisms to external environment (<8 ℃) was accelerated owing to electrolysis, where the populations with same functions can be gathered together to resist the change of the extreme environment. However, the cooperative relationship among microorganisms in E-TFCW was weakened at 4 ± 1 ℃. PICRUSt analysis results further demonstrated that the abundance of extracellular electron transfer related functional genes was increased. This study provides new insights into electrolysis-integrated constructed wetland functioning stability for accelerating antibiotics removal in cold environment.

Catalytic degradation of sulfamethoxazole by peroxymonosulfate activation system composed of nitrogen-doped biochar from pomelo peel: Important roles of defects and nitrogen, and detoxification of intermediates

Nitrogen doping could improve the catalytic performance of carbon materials, in which the nitrogen configuration could be used as active sites for peroxymonosulfate (PMS) activation. Herein, this paper studied how to turn waste to “treasure” by agriculture waste pomelo peel to prepare nitrogen-doped biochar and successfully applied it to advanced oxidation field. The effects of the sodium bicarbonate (NaHCO3), melamine, and pyrolysis temperature on the catalytic activity of biochar for the removal of sulfamethoxazole (SMX) were investigated. The optimized nitrogen-doped biochar (C−N−M 1:3:4) possessed high specific surface area (SSA, 738 m2/g) and high level of nitrogen doping (nitrogen content 13.54 at%). Accordingly, it exhibited great catalytic performance for PMS activation to remove SMX antibiotic, and 95% of SMX was removed within 30 min. High catalytic activity of C−N−M 1:3:4 was attributed to rich defects, carbonyl group, high content of graphitic N and pyrrolic N, and large SSA, in which non-radical oxidation process based on singlet oxygen (1O2) and electron transfer contributed to the SMX degradation. The prepared nitrogen-doped biochar possessed high stability and reusability and the removal efficiency of SMX still reached 80% after four cycles. Additionally, the phytotoxicity assay indicated that the toxicity of degradation intermediates was obviously decreased in the PMS/ C−N−M 1:3:4 system.

Molybdenum disulfide (MoS2) promoted sulfamethoxazole degradation in the Fe(III)/peracetic acid process

• MoS 2 /Fe(III)/PAA process was first developed to degrade sulfamethoxazole. • Fe(IV), 1 O 2 , HO ● , CH 3 C(O)O ● , and CH 3 C(O)OO ● were evidenced as reactive species. • Influencing factors were comprehensively studied. • Sulfamethoxazole degradation pathway was proposed with identifying oxidation products. • A continuous flow reactor configuration with MoS 2 -immobilized sponge was developed. Activation of peracetic acid (PAA) for pollutants degradation has been a hotspot recently. In this study, molybdenum disulfide (MoS 2 ) was first employed to enhance sulfamethoxazole (SMX) degradation in the Fe(III)/PAA process at pH 3.0. The addition of MoS 2 can not only accelerate the transformation from Fe(III) to Fe(II), but also can directly activate PAA. A series of reactive species including Fe(IV), 1 O 2 , HO ● , CH 3 C(O)O ● and CH 3 C(O)OO ● were generated in this Fe(III)/MoS 2 /PAA process, which was responsible for SMX degradation except 1 O 2 . The increase of MoS 2 dosage (0.025–0.2 g/L) accelerated SMX degradation, and the optimum pH was 3.0. The increase of either PAA (0.075–0.45 mM) or Fe(III) concentration (0.025–0.2 mM) also accelerated SMX degradation. However, the higher concentration of SMX, the addition of humic acid, and extra adding H 2 O 2 lowered the removal efficiency of SMX. Based on the identified products, possible pathways of SMX degradation initiated by electron transfer reaction were proposed. Furthermore, a continuous flow reactor configuration was employed to recycle the used MoS 2 , and the stable removal efficiency of SMX during 6 h reaction brings a new strategy for this process in practical use. This study developed an efficient method to remove SMX and provided a new idea for the PAA activation in water treatment.

Photo-catalytic degradation of sulfamethoxazole from aqueous solutions using Cu-TiO2/ CQDs hybrid composite, optimisation, performance and reaction mechanism studies

ABSTRACT Cu doped TiO2 decorated with carbon quantum dots (CQDs), called Cu-doped TiO2/CQD, was synthesised as a photocatalyst, and then used in the degradation of sulfamethoxazole (SMX) antibiotic. The properties of the synthesised catalyst were determined by FT-IR, XRD, FESEM, TEM, EDX, BET and UV–Vis DRS analysis. These analyses showed successful doping of TiO2 with Cu coated by CQDs. Variable parameters such as different CQDs ratios, photocatalyst dosage, initial concentration of SMX, pH and intensity of visible light were investigated. The best removal efficiency of SMX was obtained at initial concentration = 20 mg/L SMX, photocatalytic dosage = 0.8 g/L, pH = 6, visible light intensity = 75 W/m2 and CQDs ratios in the composite = 4% wt during 60 min reaction time. The photocatalytic degradation kinetic of SMX fitted well with the pseudo-first-order kinetic model. Experiments showed that HO• and O2 • – were active species in the photocatalytic destruction of SMX and O2 • – had more inhibiting effects in the SMX degradation process. The synthesised photocatalyst was used for six cycles with a slight reduction in the SMX degradation efficiency. TOC removal efficiency was 81% at optimal condition.

Application of energy sustainable utilization strategy for highly efficient electro-Fenton treatment of antibiotics

An innovative nitrogen-doped sludge-derived biochar (NSBC) electro-Fenton cathode was fabricated by a hydrothermal and pyrolysis combination method, which was applied to the degradation of sulfamethoxazole (SMX). The superficial characteristics of the optimal cathode (NSBC*@Ni-F) showed a large number of oxygen reduction reaction (ORR) electrocatalytic active sites under acidic conditions with high electrons transfer efficiency. The two nitrogen species (pyridinic-N and graphite-N) dominated the ORR electrocatalytic active sites. The H2O2 yield (195.99 mg L−1) and corresponding current efficiency (73.69 ± 1.2%) using NSBC*@Ni-F cathode were 7 times higher than that of bare sludge biochar as cathode in EF system. An excellent SMX removal efficiency (95.72%) was achieved as well. The TOC removal achieved 85.11% and corresponding energy consumption reached as low as 12.03 kW h kg−1. Rational reaction intermediates were put forward during EF procedure to predict and explore the SMX degradation pathway for water remediation. This study is hopeful to hew out a new road to develop eco-friendliness and cost-effective cathode material in EF system with adequate activity and reuse stabilization.

Enhanced performance and mechanisms of sulfamethoxazole removal in vertical subsurface flow constructed wetland by filling manganese ore as the substrate

Sulfamethoxazole (SMX), a typical sulfonamide antibiotic, is ubiquitous in secondary effluent and may pose undesirable effects on the aquatic ecosystem and human health. Constructed wetland (CW) is more and more applied in advanced sewage treatment, and the substrate plays an important role in removing pollutants. Manganese (Mn) ore has been widely concerned as a new type of substrate to remove pollutants in CW due to its high adsorption and redox properties. However, the removal mechanism of antibiotics by Mn ore CW is still unclear. In this study, Mn ore was selected as the substrate of a vertical flow constructed wetland (VFCW) while gravel substrate was selected as a control group, and the removal efficiencies of SMX in two VFCWs were investigated and compared. Experimental devices were layered as different regions, including anaerobic (0–32 cm), anoxic (32–64 cm) and aerobic (64–80 cm) zones, to examine the removal characteristics of SMX in different regions. And the removal mechanism of SMX was also explored by examining the adsorption and oxidation of Mn ore and the microbial degradation performance. The results showed that the final removal efficiency of SMX in CW filled with Mn ore substrate (M-CW) (48.4%) increased by 39.6%, compared with CW filled with gravel substrate (G-CW) (8.8%). According to the calculation of mass balance, the total loss of SMX caused by the oxidation of Mn ore and biodegradation accounted for 33.0% of the total SMX input in M-CW, the SMX loss caused by the biodegradation in G-CW accounted for 13.0%, and the substrate adsorption in M-CW and G-CW occupied 15.0% and 7.0% of the total SMX input, respectively. Mn(II) was formed during the oxidation of SMX by Mn(III, IV) and dissimilated Mn(III, IV) reduction by microorganisms in anaerobic environment (0–32 cm). Whereafter, the produced Mn(II) entered into the aerobic zone (64–80 cm) with the water flow and was re-oxidized into biogenic Mn oxides (BioMnOx) which had high adsorption and oxidation performance for SMX. Therefore, Mn ore could enhance SMX removal efficiency in anaerobic and aerobic zones by Mn redox process.

Activation of peroxymonosulfate by the CoFe/ZSM-5 for efficient sulfamethoxazole degradation

The CoFe/ZSM-5 catalyst was successfully synthesized through the impregnation method and used for peroxymonosulfate (PMS) activation to degrade sulfamethoxazole (SMX). The CoFe/ZSM-5 sample showed more excellent catalytic performance than that of Co/ZSM-5 and Fe/ZSM-5 due to the synergistic effect between Co and Fe, and the removal efficiency of SMX reached to 93% within 60 min. Total organic carbon (TOC) removal rate was 85% in the CoFe/ZSM-5/PMS reaction system. In addition, the CoFe/ZSM-5/PMS system showed excellent catalytic ability on SMX degradation in the pH range of 6.0–9.0. The CoFe/ZSM-5 sample showed excellent stability and reusability, and the degradation efficiency of SMX still reached to 90% in the fifth run. The quenching experiment proved that SO4-·and 1O2 active species were produced, and 1O2 played a dominant role during the degradation process. This study provides an efficient strategy for the preparation of heterogeneous catalysts used as the PMS activator to degrade organic pollutants in wastewater.

Sulfamethoxazole removal of adsorption by carbon – Doped boron nitride in water

Carbon doped boron nitride (BCN) was synthesized by one-step oxygen limiting method. The BCN was characterized by XRD, SEM, FTIR, XPS and Zeta. The effects of initial concentration, time, pH and temperature of BCN on the removal of Sulfamethoxazole (SMX) were also studied. The experiments showed that the removal efficiency of SMX by BCN was better at low temperature. In the first ten minutes, the adsorption effect is very fast, and the adsorption capacity can basically reach half of the total adsorption capacity. According to the adsorption kinetic model of SMX adsorbed by BCN in solution, it was found that the adsorption conforms to pseudo second-order kinetic model and belongs to chemical adsorption. By fitting the adsorption isotherm, it was found that the fitting was more consistent with Langmuir adsorption isotherm model, and the maximum adsorption capacity was 28.75 mg·g-1 at 10 °C. In addition, the thermodynamics of adsorption was also studied, which proved that the reaction could be spontaneous. Moreover, the adsorption mechanism of BCN on SMX includes hydrogen bonding, π-π interactions and electrostatic interaction. And, after six adsorption/desorption cycles, the adsorption capacity can still reach 82%.

Phytoremediation mechanisms and plant eco-physiological response to microorganic contaminants in integrated vertical-flow constructed wetlands

Vegetations play a vital role in the ecological function of constructed wetlands (CW), but the systemic phytoremediation mechanism of CW is still unclear. An integrated vertical-flow constructed wetland (IVCW) was established to elucidate the phytoremediation mechanisms and plants eco-physiological response to an emerging contaminant, sulfamethoxazole (SMX). Attenuation of SMX in IVCW with and without vegetation (Acorus calamus) are comparatively analyzed. The results showed significant enhancement of removal efficiencies of total nitrogen (via intensified denitrification) and SMX by up to 10% respectively with vegetation. A unique micro-rhizo environment was created by stimulating the denitrifiers, Clostridium_sensu_stricto, Ignavibacterium, Rhodanobacter, and Geobacter. Free-living plant growth-promoting bacteria, unclassified_Burkholderiales and unclassified_Betaproteobacteria, proliferated in the rhizosphere, protecting the growth mechanism of A. calamus and, consequently, promoting performance of the IVCW. Overall, A. calamus exhibited tolerance to SMX, maintaining its photosynthesis rate and stabilizing the plant cell structure by an effective antioxidant system. The growth and defense mechanisms of A. calamus appeared to positively correlate with the IVCW performance, whereby the photosynthetic rate and antioxidant enzymes activities peaked together with the maximum removal efficiency of TN (77.81%) and SMX (99.88%). The contribution of vegetation to ecotoxicity reduction in CW might be underrated as absorbed SMX could be phytodegraded into less toxic metabolites via specific enzymes.

Performance and mechanism of sulfamethoxazole removal in different bioelectrochemical technology-integrated constructed wetlands

Sulfamethoxazole (SMX) has a high concentration and detection frequency in aquatic environments due to the poor removal efficiency of traditional biological treatment processes. Bioelectrochemical technology-integrated constructed wetlands (CWs) have great potential for SMX removal; however, the process of SMX removal in different bioelectrochemical technology-integrated CWs (microbial fuel cell (MFC) and direct current (EC)) remains unclear. To address this, we examined the mechanism of SMX removal in MFCCW and ECCW. The results revealed that the SMX removal efficiency can reach 96.0 ± 2.4% in the ECCW and 97.2 ± 2.2% in the MFCCW. The enhancement of MFC for SMX removal in CW was slightly better than that in direct current (p > 0.05). It was found that the adsorption process of SMX in the substrate promoted by EC was more enhanced than that by MFC. Furthermore, bioelectrochemical technology improved plant activity, including root and enzymatic (superoxide dismutase, peroxidase, and catalase) activities, and fluorescence parameters (photochemical quenching coefficient, non-photochemical quenching coefficient, and quantum efficiency of PS II). Significant differences were found between CW and ECCW (p < 0.05), while no significant differences were found between CW and MFCCW (p > 0.05). The microbial activity and abundance in CW were improved by bioelectrochemical technology, and the microbial community structure was optimised to be simpler and more stable. However, EC tended to promote microbial and plant activity in CW, whereas MFC tended to optimise the microbial community and improve the tightness and stability of the module. The enhanced difference might also account for the changes in the SMX degradation pathway. 4-aminobenzenesulfonic acid (TP174), 3-amino-5-methylisoxazole (TP99) and 5-methylisoxazole (TP84) were all common products in the three reactors, whereas TP99 underwent further ring-opening in MFCCW and TP174 underwent further hydrolysis in ECCW. This study provided an important reference for the targeted regulation of plants and microorganisms in constructed wetlands via different bioelectrochemistry to enhance characteristic pollutants degradation.

Heterogeneous photo-Fenton degradation toward sulfonamide matrix over magnetic Fe3S4 derived from MIL-100(Fe)

Magnetic Fe3S4 was facilely derived from MIL-100(Fe) as the precursor and thioacetamide (TAA) as the sulfur source under hydrothermal condition. The as-prepared Fe3S4 was adopted as catalyst to promote the photo-Fenton process, in which sulfamethoxazole (SMX) was used as representative pollutant sample to test the oxidative degradation performance of Fe3S4. The results showed that Fe3S4 exhibited excellent photo-Fenton-like oxidation decomposition performances toward sulfamethoxazole (SMX) under both UV and visible light. A possible degradation mechanism over Fe3S4 in the photo-Fenton reaction is put forward based on quenching experiments and electron spin resonance (ESR). About 41% total organic carbon (TOC) removal efficiency of sulfamethoxazole (SMX) over the as-prepared Fe3S4 can be accomplished within 40 min. As well, different sulfonamide antibiotics (SAs) like sulfamethoxazole (SMX), sulfisoxazole (SIM) and sulfadiazine (SDZ) were selected to further investigate the oxidative degradation activity of Fe3S4 in this photo-Fenton-like reaction system, in which the possible degradation pathways of SMX, SIM and SDZ were put forward based on UHPLC-MS analysis. This work provided a new strategy to prepare magnetic Fe3S4 as catalyst for advanced oxidation process, which can be easily separated from the treated water samples to accomplish facile recovery and recyclability.

Effects of sulfamethoxazole on aerobic sludge granulation process.

Our purpose was to clarify the effect of sulfamethoxazole (SMX) on the start-up period, particle formation, and treatment efficiency of an aerobic granular sludge system. We compared an R1granular sequencing batch reactor (GSBR) started with 5μgL-1 SMX and an R2 GSBR started without SMX, as a control, to investigate the impact of a trace amount of SMX (5μgL-1 ) on aerobic granular sludge (AGS) characteristics and the removal of conventional contaminants. AGS granulation in the R1system was not inhibited by SMX, but the granule particle size was smaller than that in the R2system. Both systems had good performance removing conventional pollutants. Extracellular polymeric substance secretion in the R1system was lower than that in the R2system. After stabilizing reactor operations, the SMX removal efficiency in the R1system (~73.93%) was higher than that in the R2system (~70.66%). The start-up modes also determined the differences in the microbial community structure of the AGS systems. SMX-activated AGS performed better than AGS without SMX. The study can help engineers determine start-up modes with varieties of antibiotics in AGS processes and provide references for the optimization of water treatment processes.

Insights into removal of sulfonamides in anaerobic activated sludge system: Mechanisms, degradation pathways and stress responses

The fate of antibiotics in activated sludge has attracted increasing interests. However, the focus needs to shift from concerning removal efficiencies to understanding mechanisms and sludge responding to antibiotic toxicity. Herein, we operated two anaerobic sequencing batch reactors (ASBRs) for 200 days with sulfadiazine (SDZ) and sulfamethoxazole (SMX) added. The removal efficiency of SMX was higher than that of SDZ. SDZ was removed via adsorption (9.91–21.18%) and biodegradation (10.20–16.00%), while biodegradation (65.44–86.26%) was dominant for SMX removal. The mechanisms involved in adsorption and biodegradation were investigated, including adsorption strength, adsorption sites and the roles of enzymes. Protein-like substance (tryptophan) functioned vitally in adsorption by forming complexes with sulfonamides. P450 enzymes may catalyze sulfonamides degradation via hydroxylation and desulfurization. Activated sludge showed distinct responses to different sulfonamides, reflected in the changes of microbial communities and functions. These responses were related to sulfonamides removal, corresponding to the stronger adsorption capacity of activated sludge in ASBR-SDZ and degradation capacity in ASBR-SMX. Furthermore, the reasons for different removal efficiencies of sulfonamides were analyzed according to steric and electronic effects. These findings propose insights into antibiotic removal and broaden the knowledge for self-protection mechanisms of activated sludge under chronic toxicities of antibiotics.

Efficiency of sulfamethoxazole removal from wastewater using aerobic granular sludge: influence of environmental factors.

The effects of adsorption, sulfamethoxazole (SMX) content, chemical oxygen demand (COD), and dissolved oxygen (DO) are recognized to be crucial for SMX removal in the aerobic granular sludge (AGS) system. Therefore, we investigated the impact of adsorption and these three different environmental factors on the SMX removal loading rate and removal efficiency of an AGS system, and determined the differences in microbial community composition under different environmental conditions. Adsorption was not the main SMX removal mechanism, as it only accounted for 5% of the total removal. The optimal SMX removal conditions were obtained for AGS when the COD, DO, and SMX concentrations were 600mg/L, 8mg/L, and 2,000µg/L, respectively. The highest SMX removal efficiency was 93.53%. Variations in the three environmental factors promoted the diversity and changes of microbial communities in the AGS system. Flavobacterium, Thauera, and norank_f_Microscillaceae are key microorganisms in the AGS system. Thauera, and norank_f_Microscillaceae were sensitive to increases in SMX concentrations and beneficial for degrading high SMX concentrations. In particular, Flavobacterium abundances gradually decreased with increasing SMX concentrations.

Long-term performance evaluation of granular activated carbon fluidization and biogas sparging in anaerobic fluidized bed membrane bioreactor: Membrane fouling and micropollutant removal

In this study, fluidization of granular activated carbon (GAC) by the recirculation of a bulk suspension through an anaerobic fluidized bed membrane bioreactor (AFMBR) and biogas sparging from the bottom of an anaerobic membrane bioreactor (G-AnMBR) for treating low-strength wastewater were compared to investigate organic removal and fouling rate. The chemical oxygen demand (COD) removal efficiency obtained by both the AFMBR and G-AnMBR exceeded 90 %, and the proportion of methane in the biogas produced was 60 % at the same hydraulic retention time (HRT). In the AFMBR, the transmembrane pressure (TMP) gradually increased, but a rapid TMP jump was not observed during operational period. In the G-AnMBR, the TMP increased rapidly as the biogas flowrate was 2 and 3 L/min (LPM) at 8 h of HRT while the TMP below 0.1 bar was maintained over 90 d at 4 LPM. Our results also indicated that organic micropollutants, such as Bisphenol A (BPA), Sulfamethoxazole (SMX), and Methylparaben (MeP), were removed by AFMBR almost completely. However, the G-AnMBR showed relatively low SMX and MeP removal efficiencies of 47.6 % and 74.9 %, respectively. The estimated energy required to operate the G-AnMBR was 1.37 kW h/m3, while it was only 0.06 kW h/m3 for AFMBR.

Enhanced catalytic sulfamethoxazole degradation via peroxymonosulfate activation over amorphous CoSx@SiO2 nanocages derived from ZIF-67

In this work, the amorphous CoSx@SiO2 nanocages were hydrothermally synthesized by sulfurizing ZIF-67@SiO2 in the presence of thioacetamide (TAA). The catalytic performances of CoSx@SiO2 nanocages as heterogeneous catalysts to activate peroxymonosulfate (PMS) for the sulfamethoxazole (SMX) degradation were systematically investigated. 100% SMX was degraded within 6 min in CoSx@SiO2/PMS system, indicating that the amorphous CoSx@SiO2 nanocages exhibited outstanding sulfate radical-advanced oxidation process (SR-AOP) activity toward SMX degradation due to the regeneration of Co2+ by surficial sulfur species like S2−/S22−. The effects of PMS dosages, initial pH, SMX concentrations and co-existing ions on SMX degradation efficiency were explored in detail. The SMX removal efficiency was obviously improved in the simulated wastewater containing chloride ions (Cl−) and low-concentration bicarbonate ions (HCO3−). The residual PMS and the generated sulfate radical (SO4·−) were determined quantitatively in CoSx@SiO2/PMS system. A possible mechanism in CoSx@SiO2/PMS system was proposed based on the results of quenching experiments, X-ray photoelectron spectroscopy (XPS) analysis, electrochemical tests, and electron spin resonance (ESR). The CoSx@SiO2 exhibited good stability and reusability, in which 100% SMX removal was achieved even after five consecutive cycles. This work provided a strategy for regulating the stability of cobalt-based catalyst for efficient pollutant degradation by PMS activation.