Antibiotic Wastewater Research Articles

Detection methods for antibiotics in wastewater: a review.

Antibiotics are widely used as fungicides because of their antibacterial and bactericidal effects. However, it is necessary to control their dosage. If the amount of antbiotics is too much, it cannot be completely metabolized and absorbed, will pollute the environment, and have a great impact on human health. Many antibiotics usually left in factory or aquaculture wastewater pollute the environment, so it is vital to detect the content of antibiotics in wastewater. This article summarizes several common methods of antibiotic detection and pretreatment steps. The detection methods of antibiotics in wastewater mainly include immunoassay, instrumental analysis method, and sensor. Studies have shown that immunoassay can detect deficient concentrations of antibiotics, but it is affected by external factors leading to errors. The detection speed of the instrumental analysis method is fast, but the repeatability is poor, the price is high, and the operation is complicated. The sensor is a method that is currently increasingly studied, including electrochemical sensors, optical sensors, biosensors, photoelectrochemical sensors, and surface plasmon resonance sensors. It has the advantages of fast detection speed, high accuracy, and strong sensitivity. However, the reproducibility and stability of the sensor are poor. At present, there is no method that can comprehensively integrate the advantages. This paper aims to review the enrichment and detection methods of antibiotics in wastewater from 2020 to the present. It also aims to provide some ideas for future research directions in this field.

Enhanced hydrolysis of spiramycin in aqueous solution using SiO2/SO3H

Abstract Sulfonated silicon dioxide (SiO2/SO3H) solid acids were synthesized and they were characterized and used for spiramycin hydrolysis pretreatment of antibiotic wastewater. Results show that the spiramycin removal effect rankings are as follows: SiO2/SO3H > SiO2 (pH = 3 or so) > control group. A first-order model was used to reflect the hydrolytic kinetics. The hydrolysis rate of the SiO2/SO3H solid acid calcined at 600°C is the highest, up to 3.59×10−2 (k). The performance of SiO2/SO3H is in positive correlation with the total acidity, which was determined by using the n-butylamine titration method. This hydrolytic method eliminates the need for the on-site handling of hazardous and corrosive mineral acids. As an attractive selective catalytic pretreatment method, it is targeted at removing related functional groups from antibiotics to reduce the inhibitory effect and allow antibiotic wastewater to further be easily biologically treated.

The efficient degradation of carbamazepine by Cu-Fe bimetallic composite carbon derived from the waste cation exchange resins: Mechanism, ecotoxicity, and continuous flow catalysis

The Cu-Fe bimetallic composite carbon (CuFeO2@CR) was synthesized by using the waste cation exchange resins as the carbon source to degrade carbamazepine (CBZ) by activating peroxymonulfate (PMS). Results found that 91.3 % of CBZ was degraded under the optimal condition ([PMS] = 0.2 g/L, [CuFeO2@CR] = 0.3 g/L, T = 25℃). CuFeO2@CR could efficiently degrade CBZ at pH 3.03–9.02 and maintain the degradation at 83.6 % in the fifth cycle. The reactive oxygen species (ROS) were SO4•−, •OH, and 1O2 with the relative contribution of 35 %, 29 %, and 36 %, respectively. DFT calculation demonstrated that CuFeO2@CR exhibited a preferential affinity for PMS and greater transfer electrons capacity than CR. Three reaction pathways were proposed in the CuFeO2@CR/PMS system, and the degradation could effectively reduce the toxicity into non-toxic. The continuous flow catalytic experiment indicated the promising application in the treatment of antibiotic wastewater. This work provides guidance and theoretical support for CBZ degradation mechanisms.

The effect of extracellular polymeric substances on the distribution and transmission of antibiotic resistance genes treating antibiotic wastewater via microbial electrolysis cells

Microbial electrolysis cells (MEC) have emerged as a prominent technology for the treatment of antibiotics-containing wastewater in recent years. However, there remains a dearth of comprehensive exploration regarding the influence of extracellular polymers substances (EPS) on the distribution and transmission of antibiotic resistance genes (ARGs) in MEC. In this study, we quantified the distribution of ARGs in MEC by Fluorescence quantitative polymerase chain reaction and explored with emphasis on impact of EPS component on ARGs transmission at under different concentrations of roxithromycin. Results showed that the absolute abundance of ARGs in the electrode biofilm was 1–2 orders of magnitude higher than that in the anolyte. Specifically, EPS-associated ARGs accounted for 2.31%–11.18% of ARGs in electrode biofilm. The presence of elevated roxithromycin concentration led to electroactive microorganisms (Geobacter and Geothrix) as potential hosts of ARGs. In addition, both protein and polysaccharide content in the electrode biofilm increased with increasing roxithromycin concentration and showed positive correlations with EPS-associated ARGs. Fluorescence quenching experiments further elucidated that tryptophan and tyrosine residues in EPS could bind to ARGs effectively, contributing the hindering the ARGs transmission between hosts. Therefore, increased EPS content within electrode biofilm could reduce the concentration of ARGs present in anolyte while also influencing ARGs distribution throughout MEC. This study provides valuable insights into the distribution of ARGs in MEC systems and the role of EPS in regulating ARGs migration.

Effects of gradual increase of ciprofloxacin and cefotaxime on nitrogen and phosphorus removal and microbial community in moving bed biofilm reactor

To clarify the effects of trace amount of antibiotics in wastewater on biofilm reactor, this study explored the effects of gradual increase of ciprofloxacin (CIP) and cefotaxime (CTX) ranging from 100 to 1000 ng·L−1 on the nitrogen and phosphorus removal and microbial community in a moving bed biofilm reactor (MBBR). Under different phases of CIP and CTX gradual increase, the resilience of culturable functional bacteria including ammonifying bacteria, nitrite oxidizing bacteria, aerobic denitrifying bacteria and phosphorus accumulating organisms in the biofilm was analyzed. High-throughput sequencing analysis was used to reveal the microbial community structure and species composition of functional bacteria. The results indicated that the treatment performance of MBBR was temporarily affected by trace CIP and CTX and returned to its original level within 1–2 days. Ammonifying bacteria exhibited strong resilience in trace CIP and CTX stress environments. Trace CIP and CTX altered the microbial community structure in biofilm, but the performance of nitrogen and phosphorus removal in MBBR was slightly affected. This might attribute to the rapid proliferation of Thauera, Dechloromonas and Candidatus_Accumulibacter on the carrier biofilm. The research results help to deepen the understanding of the impact of trace antibiotics on the MBBR and to provide a reference for the development of microbial germplasm resources for biological nitrogen and phosphorus removal from wastewater under antibiotic stress conditions.

Scavenger-free solar photocatalytic degradation of Textile Dyes and Antibiotics using magnetically separable bi-junctional photocatalyst

The field of solar photocatalysis has been plagued by photocatalysts with low photon-to-electron conversion efficiency, resulting in poor photocatalytic degradation rates of water pollutants. With a keen idea to improve the existing photocatalysts, we developed a scavenger-free, magnetically separable, bi-junctional solar photocatalyst. The photocatalyst comprises Fe2+ doped zinc ferrite as core, ZnO as shell, and irregular CuO nanoparticles in conjunction with the surface of core-shell nanoparticles prepared using a combination of microwave-assisted solvothermal technique and microwave-assisted reflux method. The photocatalytic degradation properties of the solar photocatalyst were modelled and optimized with the help of Methyl Orange under direct sunlight. This novel composite degrades Methyl Orange roughly four times faster than core-shell nanoparticles. The photocatalyst meets most of the criteria for working of a promising solar photocatalyst, such as 1) excellent absorption of sunlight, 2) two physically distinct heterojunction and absorbing regions for efficient charge carrier generation and separation, 3) scavenger-free degradation of textile dyes and antibiotics, 4) High surface area (39 m2g −1), 5) good stability, 6) excellent reusability, 7) and easy separation of nanoparticles for reuse with the help of a magnet. The prepared photocatalyst efficiently degrades fluoroquinolone antibiotics such as Ciprofloxacin Hydrochloride, Norfloxacin, and Ofloxacin. The photocatalyst demonstrates the capability to efficiently degrade textile dyes such as Methyl Orange, Methylene Blue, Orange G, Fluorescein sodium salt, Rhodamine B, and Crystal Violet. Additionally, the bi-junctional photocatalyst can be coated with a thin layer of silver to achieve twice the degradation rate. This enhancement is attributed to the Localized Surface Plasmon Resonance (LSPR) effect. The current work presents an effective and economical option for removing dyes and antibiotics in wastewater, marking a significant stride towards sustainable industrial practices.

Z-scheme Ag2O/ZnO heterostructure on carbon fibers for efficient photocatalysis of tetracycline

Antibiotics can be transferred from water bodies to soil environment through irrigation, and then enriched in agricultural products, causing larger scale pollution. Due to the ability of antibiotics to inhibit microbial activity, the use of traditional microbial methods is not suitable for treating wastewater containing antibiotics. In nowadays, photocatalytic technology has been widely studied to deeply mineralize low concentration water-soluble pollutants like antibiotics. However, the photocatalytic technology still faces two challenges, namely the difficulty of recovering and reusing powdered catalysts, and the insufficient activity of catalysts. In this work, we designed a Z-scheme Ag2O/ZnO heterostructure in situ grown on large scaled carbon fiber (named CF/ZnO/Ag2O) to enhance the efficiency of photocatalysis of tetracycline (TC) in water. The large-area carbon fiber cloth facilitates the recovery and industrial application of the catalyst, while the Z-scheme heterojunction structure significantly enhances the charge separation efficiency and catalytic performance. The results show that the interface formed by the close contact between ZnO and Ag2O provides an effective channel for charge transfer between them. Compared with existing catalysts, the prepared Z-scheme Ag2O/ZnO photocatalyst not only has higher activity, but also could solve the problem of easy loss and difficult recycling of powdered catalysts in water. Importantly, the efficiency for photocatalysis of tetracycline (TC) over CF/ZnO/Ag2O is about 94.50%, and after sixth cycles, the degradation rate is still 81.32%. The catalyst grows in situ on the surface of carbon fibers and is not easily detached. The degradation pathways of TC, toxicity analysis of intermediates and mechanism of the photocatalysis over CF/ZnO/Ag2O were explored. These characteristics make this catalyst have higher practical application potential and value, especially in improving the biodegradability of antibiotic wastewater and achieving deep purification of wastewater to improve effluent quality.

Multifunctional biomolecular corona-inspired nanoremediation of antibiotic residues.

Facing complex and variable emerging antibiotic pollutants, the traditional development of functional materials is a "trial-and-error" process based on physicochemical principles, where laborious steps and long timescales make it difficult to accelerate technical breakthroughs. Notably, natural biomolecular coronas derived from highly tolerant organisms under significant contamination scenarios can be used in conjunction with nanotechnology to tackling emerging contaminants of concern. Here, super worms (Tubifex tubifex) with high pollutant tolerance were integrated with nano-zero valent iron (nZVI) to effectively reduce the content of 17 antibiotics in wastewater within 7 d. Inspired by the synergistic remediation, nZVI-augmented worms were constructed as biological nanocomposites. Neither nZVI (0.3 to 3 g/L) nor worms (104 to 105 per liter) alone efficiently degraded florfenicol (FF, as a representative antibiotic), while their composite removed 87% of FF (3 μmol/L). Under antibiotic exposure, biomolecules secreted by worms formed a corona on and modified the nZVI particle surface, enabling the nano-bio interface greater functionality, including responsiveness, enrichment, and reduction. Mechanistically, FF exposure activated glucose-alanine cycle pathways that synthesize organic acids and amines as major metabolites, which were assembled into vesicles and secreted, thereby interacting with nZVI in a biologically response design strategy. Lactic acid and urea formed hydrogen bonds with FF, enriched analyte presence at the heterogeneous interface. Succinic and lactic acids corroded the nZVI passivation layer and promoted electron transfer through surface conjugation. This unique strategy highlights biomolecular coronas as a complex resource to augment nano-enabled technologies and will provide shortcuts for rational manipulation of nanomaterial surfaces with coordinated multifunctionalities.

Visible light-improved periodate activation of natural chalcopyrite particles towards effective pollutants degradation

The aim of this paper is to build an efficient and low-cost advanced oxidation system to realize the antibiotic wastewater purification which has a realistic significance. In this study, a system of visible light-assisted activation of natural chalcopyrite to activate periodate was adopted to remove tetracycline (TC). The results demonstrated that the removal efficiency (100% within 60 min) of TC in the CuFeS2/PI/Light system was significantly improved compared to the CuFeS2/PI system or PI process alone, and the degradation rates of TC in the CuFeS2/PI/Light system were 5.9 times higher than that of the CuFeS2/PI system, which is attributed to the synergistic effect of light and PI activation. The system also effectively degraded sodium butyl xanthate (SBX), chlortetracycline hydrochloride (CTC) and Rhodamine B (RhB), while the efficiency of the degradation process was further enhanced in natural water quality. The active substance quenching experiment revealed that [Formula: see text]OH, 1O2, O2[Formula: see text], IO4[Formula: see text] and IO3[Formula: see text] were the main substances to achieve effective TC removal. In addition, the cycling of Cu[Formula: see text]/Cu[Formula: see text] and Fe[Formula: see text]/Fe[Formula: see text] present in chalcopyrite improved the activation of PI. Further, visible light is conducive to the valence cycling of Cu and Fe, as well as the production of more oxidizing free radicals, thus achieving the synergy of photocatalysis and PI activation. This study provides a low-cost and efficient advanced oxidation pathway for the removal of antibiotic wastewater.

Removal of sulfadiazine from water by a three-dimensional electrochemical system coupled with persulfate: Enhancement effect of ball-milled CuO-Fe3O4@biochar

The CuO-Fe3O4@biochar (CFB) composite, synthesized via an eco-friendly mechanical ball milling, was employed as a particle electrode in a three-dimensional (3D) electrochemical reactor to investigate its efficiency in removing sulfadiazine (SD) from antibiotic wastewater. The study revealed that the addition of 5 g/L CFB into the 3D electrochemical system significantly enhanced SD removal, achieving a removal rate of 96.2 % compared to 33.5 % in a two-dimensional system, under optimal conditions of pH 7, persulfate concentration of 4 mM, and current density of 8 mA/cm2. The CFB particle electrode demonstrated superior catalytic activity compared to CuB, FeB, and CuFe particle electrodes. The ball milling process effectively reduced the agglomeration of CuO and Fe3O4, thereby increasing the active sites of the particle electrodes. The SD displayed remarkable removal efficiency across a broad pH spectrum ranging from 2 to 9. Scavenging experiments and electron paramagnetic resonance techniques suggested that SD removal primarily occurred via a non-radical pathway involving singlet oxygen (1O2). The synergistic effect between bimetallic ions and the reduction reaction at the cathode accelerated the cycling of Fe2⁺/Fe3⁺ and Cu⁺/Cu2⁺, thereby promoting PDS activation. Additionally, the positively charged surface of CFB facilitated contact with PDS through electrostatic attraction. The E-CFB-PDS system demonstrated excellent efficiency in removing antibiotics, and its stability and reusability make it a promising approach for treating organic pollutant wastewater.

Peroxymonosulfate activated by CoMn@CNT nanocomposite for moxifloxacin degradation

As a fourth quinolone drug, the efficient and rapid degradation of moxifloxacin (MOX) remain a rigorous problem. Peroxymonosulfate (PMS)-based oxidation method poses a promising application prospect for refractory antibiotic wastewater with an excellent degradation efficiency. Herein, the Co/Mn doped-carbon nanotube catalyst (CoMn@CNT) was successfully synthesized by a two-step pyrolysis method and applied to activate PMS for MOX degradation. The degradation efficiency of MOX could reach 89.7 % in 30 min with relatively low concentrations of PMS (100 mg/L) and CoMn@CNT (30 mg/L). The effects of catalyst dosage, PMS dosage, initial pH, reaction temperature, and co-existing ions for the degradation of MOX were investigated. The CoMn@CNT/PMS system possessed wide pH application range (3.0–11.0). Sulfate radical (SO4−) was verified as the dominant reactive species responsible for degradation of MOX by quenching experiment. Finally, the possible MOX degradation pathways were also proposed. Overall, this study could provide some inspirations of the CoMn@CNT/PMS as a new system which applied to wastewater treatment of antibiotics.

Layer-by-layer adsorption behavior of Cr(VI) on MoS2@Mt induced by sulfamethoxazole

Hexavalent chromium (Cr(VI)) contamination in wastewater is a serious environmental threat. Cr(VI) removal is often interfered by antibiotics in wastewater, however, the underlying mechanism remains unclear. Here, molybdenum disulfide/montmorillonite (MoS2@Mt) composites were prepared and used for Cr(VI) removal to reveal the adsorption behavior of Cr(VI) on MoS2@Mt induced by sulfamethoxazole. The induction effect of the typical antibiotic sulfamethoxazole (SMX) was investigated. The adsorption capacity of MoS2@Mt was maximum at pH 2 and decreased with increasing pH. The performance results showed that SMX promoted Cr(VI) removal, with a maximum increase of 14.80 % in removal efficiency. Cr(VI) adsorption on MoS2@Mt followed the Langmuir model, whereas it was more consistent with the Freundlich model in the presence of SMX. This suggested that SMX induced a monolayer to multilayer shift in Cr(VI) adsorption. XPS results indicated that Cr(VI) removal pathways included Cr(VI) adsorption, chemical reduction of Cr(VI) to trivalent chromium (Cr(III)), and Cr(III) chelation. In particular, electrostatic pulling, coordinated adsorption, and hydrogen bond attraction contributed to Cr(VI) adsorption. Mechanism investigation suggested that Cr(VI) or SMX absorbed on the material surface continued to absorb SMX or Cr(VI) by electrostatic attraction, resulting in layer-by-layer adsorption behavior, which facilitated Cr(VI) removal. In actual wastewater treatment, MoS2@Mt reduced Cr(VI) concentrations (0.15–5 mg/L) to below the World Health Organization standard of 0.05 mg/L in the presence of 0.32 mg/L SMX. Overall, this study revealed the mechanism of SMX-induced Cr(VI) adsorption behavior, which favors the elimination of Cr(VI) from real complex wastewater.

Synergistic combination of Mn/Fe bimetal-doped carbon nitride and peroxymonosulfate for efficient photocatalytic degradation of antibiotics

The widespread of antibiotics has resulted in potential threats to the aquatic environment and human health. The visible light-assisted peroxymonosulfate (PMS) activation method is considered to be an effective way to remove antibiotics in wastewater. In this study, Mn/Fe bimetal doped graphitic carbon nitride (MnFe-CN-x) was first synthesized for PMS activation under visible light towards tetracycline (TC) removal. The optimized MnFe-CN-50 possessed the excellent photocatalytic activity, PMS activation performance and photo-Fenton-like synergistic effect. In the photo-Fenton-like system, TC (20 mg L−1) was degraded by 99 % in 50 min and the kinetic constant was 0.074 min−1. The high dispersion of Mn and Fe in carbon nitride inhibited the recombination of charge carriers in MnFe-CN-x, increased its photocurrent density and charge mobility, effectively optimized the electronic structure, and promoted the generation of 1O2. Based on the analytical results of predictive toxicity evaluation software (TEST), it was confirmed that MnFe-CN-x could effectively reduce the environmental risks associated with antibiotic contamination. This study provided new insights into synthesizing bimetal-doped graphitic carbon nitride and the use of synergistic effects of photocatalysis and PMS activation to remove organic pollutants from wastewater.

Reevaluating biostimulation strategies: the impact of humic acid on ofloxacin bioadsorption

The exogenous addition of humic acid (HA) is often seen as a biostimulation strategy to expedite the bioremediation of various pharmaceutical pollutants. Nevertheless, the impact of HA on the bioadsorption of ofloxacin (OFL), the main pathway for OFL removal in activated sludge, remains unknown. In this study, the presence of 10 mg/L HA notably decreased the theoretical OFL adsorption capacity from 8.94 to 7.95 mg/g. The inhibitory effect persisted across varying pH and ionic strengths and became more pronounced with increasing HA concentration. The morphological changes on biosolid (BIO) induced by HA indicated that HA was bioadsorbed, which in turn competed with OFL for metal binding sites like Ca and Mg on BIO. Further analysis of the OFL-HA interaction reveals the involvement of hydrogen bonding and electrostatic attraction. The study also demonstrates the bridging role of HA between OFL and BIO through consecutive desorption and re-absorption processes of OFL in the presence of HA. To quantify the direct and indirect adsorption ratios, a new approach was proposed, which determined the mass ratios of direct (OFL:BIO) and indirect bioadsorption (OFL:HA:BIO) as 1:192 and 1:21:854, respectively. These findings suggest that the indirect OFL adsorption through the HA bridge could not compensate for the adverse effects caused by the reduction of metal binding sites. Overall, this study calls for a reassessment of the addition of HA in the bioremediation process of OFL. Considering that HA widely coexists with antibiotics in wastewater, the study also provides valuable insights into OFL removal mechanisms in WWTPs.

Insights on the efficiency and contribution of single active species in photocatalytic degradation of tetracycline: Priority attack active sites, intermediate products and their toxicity evaluation

Photocatalysis has been proven to be an excellent technology for treating antibiotic wastewater, but the impact of each active species involved in the process on antibiotic degradation is still unclear. Therefore, the S-scheme heterojunction photocatalyst Ti3C2/g-C3N4/TiO2 was successfully synthesized using melamine and Ti3C2 as precursors by a one-step calcination method using mechanical stirring and ultrasound assistance. Its formation mechanism was studied in detail through multiple characterizations and work function calculations. The heterojunction photocatalyst not only enabled it to retain active species with strong oxidation and reduction abilities, but also significantly promoted the separation and transfer of photo-generated carriers, exhibiting an excellent degradation efficiency of 94.19 % for tetracycline (TC) within 120 min. Importantly, the priority attack sites, degradation pathways, degradation intermediates and their ecological toxicity of TC under the action of each single active species (·O2−, h+, ·OH) were first positively explored and evaluated through design experiments, Fukui function theory calculations, HPLC-MS, Escherichia coli toxicity experiments, and ECOSAR program. The results indicated that the preferred attack sites of ·O2− on TC were O20, C7, C11, O21, and N25 atoms with high f+ value. The toxicity of intermediates produced by ·O2− was also lower than those produced by h+ and ·OH.

Tetracycline degradation by peroxydisulfate activated with the composite material of biochar and cobalt-modified carbon nitride: Efficiency, stability, and degradation pathway

In recent years, non-homogeneous peroxydisulfate (PDS) activation for organic pollutant degradation has gained interest. Nonetheless, PDS activation using transition metal and carbon catalysts faces challenges such as metal leaching and inadequate catalytic performance. Herein, biochar-loaded cobalt-modified carbon nitride composite material (BC@CN-Co) was synthesized and employed as an activator for PDS activation. The outcomes suggested that the degradation efficiency of tetracycline (TC) could reach 82 % within 360 min under the optimized condition (TC = 5 mg/L, BC@CN-Co = 1 g/L, PDS = 2 mM, nature pH, T = 25℃), with corresponding apparent rate constant (Kobs) of 0.00375 min−1, which was approximately 5.5 and 2.0 times that of the biochar/PDS (0.00068 min−1) and cobalt-modified carbon nitride/PDS (0.00178 min−1) systems, respectively. BC@CN-Co exhibits excellent degradation of TC within a pH range of 3–7, with Cl-, NO3-, H2PO4-, and HA having little effect on TC degradation. Mechanistic experiments confirmed that the non-radical pathway mediated by singlet oxygen (1O2) and electron transfer plays an important role in TC degradation in the BC@CN-Co/PDS system. Furthermore, BC@CN-Co could efficiently reduce the leaching of Co ions to prevent metal pollution. This study provides an alternative PDS activator for the degradation of antibiotics in wastewater.

Design of a novel direct Z-scheme BiOIO3/Bi2WO6 heterojunction for enhanced photocatalytic degradation of norfloxacin under visible light

The unique electronic structure, appropriate bandgap energy, and excellent electron transfer capability make bismuth-based semiconductors hotspots in the field of photocatalysis. Novel BiOIO3/Bi2WO6 Z-scheme heterojunctions were fabricated via in-situ hydrothermal synthesis. The BIOBIW-3 heterojunctions (BiOIO3:Bi2WO6=0.25:0.8, mole ratio) exhibited excellent photocatalytic activity for norfloxacin (NOR), with a degradation efficiency of 90.41 % after 90 min of photoreaction and a reaction kinetic constant of 0.02132 min−1, which was 5.02 and 9.35 times higher than that of BIO and BIW, respectively. The superior photocatalytic performance can be attributed to the intimate interface between BiOIO3 and Bi2WO6, as well as the staggered energy band structure that facilitates the formation of a Z-type heterojunction. This not only widens the range of visible light absorption but also enhances the separation and transfer of photogenerated carriers while maintaining a high capacity for redox reactions. The dominant active species in the degradation process were photogenerated holes (h+) and superoxide (∙O2−) radicals, and an in-depth exploration of the possible mechanism was conducted. Furthermore, the effects of various parameters, including solution pH, catalyst dosage, and NOR concentration on the photocatalytic degradation of NOR were also investigated. The prepared BiOIO3/Bi2WO6 heterojunctions exhibited remarkable photocatalytic performance and chemical stability, presenting a novel research direction for employing layered bismuth-based materials in the degradation of fluoroquinolone antibiotic wastewater.

Hydrogen peroxide activation by in-situ-loaded CuS/biochar photocatalyst: The critical role of sulfur species in regulating active species

Although metal sulfides have demonstrated exceptional catalytic properties in Fenton-like reactions, little is known about the role of sulfur species in transforming highly active species responsible for degradation organics. CuS (∼12 nm) nano-capsules embedded in the biochar (CuS-BC) were prepared from copper-rich biomass, which could activate H2O2 (4 mM) and completely remove tetracycline (TC) from water within 210 min. Compared with BC/H2O2/Vis system, the degradation efficiency of TC in the CuS-BC/H2O2/Vis system was improved by 14.8 times, and the utilization efficiency of H2O2 was improved by 86 times. The whole degradation process of TC can be divided into two stages: quasi-first-order reaction kinetics (kobs = 0.015 min−1) and zero-order reaction kinetics (kobs = 6.457 mol/L/min). Within 90 min, H2O2 is activated to produce hydroxyl radicals (OH) by surface Cu2+ on CuS and photogenerated electrons (e−) generated from CuS photoexcitation, which react immediately with surface SO32− to form SO4−. After 90 min, CuIII-peroxo species (CuIII-O22−-(SO32−)n) formed by electron transfer between CuI, O2, and surface SO32− oxidize the remaining 50 % TC through interface interaction. CuS-BC catalyst exhibits excellent photostability and suitability for actual antibiotic wastewater. Overall, this study offers mechanistic insight into the role of sulfur species in the sulfide-based Fenton reactions.

BiVO4-Based Photocatalysts for the Degradation of Antibiotics in Wastewater: Calcination Role after Solvothermal Synthesis

BiVO4-Based Photocatalysts for the Degradation of Antibiotics in Wastewater: Calcination Role after Solvothermal Synthesis

Effect of Stepwise Exposure to High-Level Erythromycin on Anaerobic Digestion.

High-level erythromycin (ERY) fermentation wastewater will pose serious threats to lake environments. Anaerobic digestion (AD) has advantages in treating high-level antibiotic wastewater. However, the fate of antibiotic resistance genes (ARGs) and microbial communities in AD after stepwise exposure to high-level ERY remains unclear. In this study, an AD reactor was first exposed to 0, 5, 10, 50, 100 and 200 mg/L ERY and then re-exposed to 0, 50, 200 and 500 mg/L ERY to investigate the effect of ERY on AD. The results show that AD could adapt to the presence of high-level ERY (500 mg/L) and could maintain efficient CH4 production after domestication with low-level ERY (50 mg/L). The AD process could achieve higher removal of ERY (>94%), regardless of the initial ERY concentration. ErmB and mefA, conferring resistance through target alteration and efflux pumps, respectively, were dominant in the AD process. The first exposure to ERY stimulated an increase in the total ARG abundance, while the AD process seemed to discourage ARG maintenance following re-exposure to ERY. ERY inhibited the process of acetoclastic methanogenesis, but strengthened the process of hydrogenotrophic methanogenesis. This work provides useful information for treating high-level ERY fermentation wastewater by the AD process.