Antibiotic-containing Wastewater Treatment Research Articles

Fate of an antibiotic and its effects on nitrogen transformation functional bacteria in integrated vertical flow constructed wetlands

• IVCW could achieve simultaneous nitrogen and antibiotic removal. • Sulfamethoxazole (SMX) removal exceeds 95% primarily via biodegradation. • Enrichment of Pseudomonas , Bradyrhizobium , Sphingomonas , Luteimonas for SMX removal. • SMX transforms nitrogen transformation process to favor ANAMMOX. This study aims to provide insights into the fate and effects of the antibiotic sulfamethoxazole (SMX) on nitrogen transformation processes in integrated vertical-flow constructed wetlands (IVCW), which is useful to create strategies to improve their degradation and combat antibiotic resistance dissemination. Findings indicated chronic exposure to SMX to cause moderate deterioration of IVCW performance for nitrogen removal (p < 0.05), with average TN removal efficiency reductions of circa 10%. High-throughput sequencing and network analysis demonstrated chronic exposure of antibiotics to impact functional bacteria, ammonium oxidizing bacteria (AOB) and ANAMMOX, significantly. ANNAMMOX emerged as a potential pathway of nitrogen removal in the IVCW, albeit with considerable accumulation of NO 3 − -N (12.76 mg/L) and carbon deficiency (C/N = 0.99). Nonetheless, IVCW provides a promising technology for the advanced treatment of antibiotic-containing wastewater, demonstrated by a high and stable removal efficiency (circa 95%) of sulfamethoxazole. Biodegradation, primarily in the first stage of the IVCW, represented the major removal pathway of SMX. Microbial network analysis and the enrichment of Pseudomonas , Bradyrhizobium , Sphingomonas and Luteimonas demonstrated potential for the biodegradation of SMX. These results provide a theoretical reference for the enhancement of nitrogen and antibiotics removal in constructed wetlands.

Photochemical degradation of chloramphenicol over jarosite/oxalate system: Performance and mechanism investigation

Rational selection of affordable catalyst and effective degradation process are significant for antibiotic-containing wastewater treatment. Herein, a photochemical catalytic system comprising of bio-synthesized jarosite and oxalic acid (Ox) was investigated for degradation of antibiotic chloramphenicol (CAP) under light irradiation. Benefiting from abundant reactive species including H2O2, OH, O2− produced in photochemical process, a 97.5 % removal efficiency of CAP was obtained within 40 min. Consecutive testing cycles indicated jarosite had excellent stability and reusability in photocatalytic system. Radical chain reaction induced by photosensitive Fe(III)-Ox complexes under light irradiation was suggested to be the main mechanism for CAP degradation. A few degradation intermediates were identified to propose the possible degradation pathways of CAP. Further investigation showed that the antibacterial activities of CAP solution towards Escherichia. coli ATCC 8739 and Staphylococcus. aureus ATCC 6538 were largely reduced after treatment by photochemical process. Typical operation parameters of light/jarosite/Ox system were also investigated. CAP degradation performance in actual water demonstrated the feasibility of light/jarosite/Ox process. Overall, the developed light/jarosite/Ox system possesses great potential for antibiotic-containing wastewater treatment.

A review on anammox process for the treatment of antibiotic-containing wastewater: Linking effects with corresponding mechanisms

Antibiotic is widely present in the effluent from livestock husbandry and the pharmaceutical industry. Antibiotics in wastewater usually have high biological toxicity and even promote the occurrence and transmission of antibiotic resistant bacteria and antibiotic resistance genes. Moreover, most antibiotic-containing wastewatercontains highconcentration of ammonia nitrogen. Improper treatment will lead to high risk to the surrounding environment and even human health. The anaerobic ammonium oxidation (anammox) with great economic benefit and good treatment effect is a promising process to remove nitrogen from antibiotic-containing wastewater. However, antibiotic inhibition has been observed in anammox applications. Therefore, a comprehensive overview of the single and combined effects of various antibiotics on the anammox system is conducted in this review with a focus on nitrogen removal performance, sludge properties, microbial community, antibiotic resistance genes and anammox-involved functional genes. Additionally, the influencing mechanism of antibiotics on anammox consortia is summarized. Remaining problems and future research needs are also proposed based on the presented summary. This review provides a better understanding of the influences of antibiotics on anammox and offers a direction to remove nitrogen from antibiotic-containing wastewater by the anammox process.

Experimental Design as a Tool for Optimizing and Predicting the Nanofiltration Performance by Treating Antibiotic-Containing Wastewater.

In recent years, there has been an increase in studies regarding nanofiltration-based processes for removing antibiotics and other pharmaceutical compounds from water and wastewater. In this work, a 2k factorial design with five control factors (antibiotic molecular weight and concentration, nanofiltration (NF) membrane, feed flow rate, and transmembrane pressure) was employed to optimize the NF performance on the treatment of antibiotic-containing wastewater. The resulting multiple linear regression model was used to predict the antibiotic rejections and permeate fluxes. Additional experiments, using the same membranes and the same antibiotics, but under different conditions of transmembrane pressure, feed flow rate, and antibiotic concentration regarding the 2k factorial design were carried out to validate the model developed. The model was also evaluated as a tertiary treatment of urban wastewater for removing sulfamethoxazole and norfloxacin. Considering all the conditions investigated, the tightest membrane (NF97) showed higher antibiotics rejection (>97%) and lower permeate fluxes. On the contrary, the loose NF270 membrane presented lower rejections to sulfamethoxazole, the smallest antibiotic, varying from 65% to 97%, and permeate fluxes that were about three-fold higher than the NF97 membrane. The good agreement between predicted and experimental values (R2 > 0.97) makes the model developed in the present work a tool to predict the NF performance when treating antibiotic-containing wastewater.

Efficient degradation of antibiotics in different water matrices through the photocatalysis of inverse opal K-g-C3N4: Insights into mechanism and assessment of antibacterial activity

The efficient degradation of fluoroquinolone antibiotics and the reduction of their antimicrobial activity were achieved in different water matrices through the photocatalysis of inverse opal potassium-doped carbon nitride (IO K-CN). The IO K-CN photocatalyst with optimum doping ratio of potassium performed much better than bulk carbon nitride and pure inverse opal carbon nitride for removing fluoroquinolone antibiotics, such as levofloxacin (LVX) and norfloxacin (NOR). The remarkably narrowed band gap resulting from potassium doping and the unique properties of the inverse opal construction jointly contributed to enhancing the activity of the photocatalyst. A possible mechanism and degradation pathway for LVX was proposed on the basis of a series of characterizations including electron spin resonance (ESR) experiments, and liquid chromatography-mass spectrometry (LC-MS) analysis. Meanwhile, the byproducts during the LVX photocatalytic degradation were shown to have much lower sterilization effect, implying that the toxicity and the potential risk of LVX were excellently reduced. The potential application for the treatment of antibiotic-containing wastewater was indicated by the excellent treatment efficiency and favorable durability of this photocatalyst.

UV photolysis as an efficient pretreatment method for antibiotics decomposition and their antibacterial activity elimination

The biological treatment of antibiotic-containing wastewater is a mainstream process, but the antibacterial activity from the persistence of antibiotics would inhibit the biological activity and function of wastewater treatment plants and lead to the risk of transmission of antibiotic resistant bacteria and genes. In this study, UV photolysis was selected as an appropriate pretreatment technology for antibiotic-containing wastewater. It could decompose many kinds of antibiotics and was not inhibited by the coexisting organics in wastewater. The antibacterial activities of five kinds of antibiotics, which were eliminated with UV irradiation, exhibited a significantly positive correlation with their parent compound concentrations. The photodecomposition of the main functional groups in antibiotics contributed to the elimination of antibacterial activity. Defluorination was the main pathway to eliminate the antibacterial activity of antibiotics containing a fluorine substituent (e.g., florfenicol and ofloxacin), while the photoinduced opening of the β-lactam ring was the most efficient route to eliminate the antibacterial activity of β-lactam antibiotics (e.g. cefalexin, amoxicillin and ampicillin). These results demonstrated that UV photolysis could be adopted as an efficient and promising pretreatment strategy for the source control of antibiotic antibacterial activity by the decomposition of antibiotic functional groups before the biological treatment unit.

Difunctional hierarchical porous SiOC composites from silicone resin and rice husk for efficient adsorption and as a catalyst support

Porous SiOC composites were prepared by varying the proportions of silicone resin and rice husk at different pyrolysis temperatures using biotemplate method. The as-prepared composites were investigated by various analytical techniques and utilized for adsorption of ciprofloxacin from wastewater and as a catalyst support. The composites consist of the SiOC matrix, silicon dioxide and free carbon. The optimized composite has the hierarchical pores with high specific surface area of 767.61 m2/g and pore volume of 0.84 cm3/g. The adsorption process of ciprofloxacin onto SiOC composites adheres to the pseudo-second-order kinetic model. The external film diffusion and intra-particle diffusion jointly control the adsorption rate, and the Langmuir and Freundlich models can properly describe the adsorption isotherms. The SiOC samples show a large adsorption capacity (148.0 mg/g) and superior reusability, suggesting its exceptional reusability and potential application in antibiotic-containing wastewater treatment. Furthermore, the photodegradation rate constant of the SiOC/g-C3N4 composite is almost 2.28 times as high as that of pristine g-C3N4, indicating that the SiOC composites can be employed in a favorable catalyst support ascribed to the enhancement of photodegradation performance after loading photocatalyst on the SiOC adsorbent.

Functionalized MIL-53(Fe) as efficient adsorbents for removal of tetracycline antibiotics from aqueous solution

Abstract Recently, metal-organic frameworks with high porosity have drawn extensive attention in environment remediation. Herein, a variety of porous metal-organic frameworks were synthesized, including MIL-53(Fe), NH2-MIL-53(Fe), NO2-MIL-53(Fe) and Br-MIL-53(Fe), to adsorb tetracycline (TCN) from aqueous solution. Results showed that the functionalized MIL-53(Fe) exhibited higher adsorption performance than the pristine MIL-53(Fe). Among MIL-53(Fe) series, Br-MIL-53(Fe) had the highest maximum adsorption capacity of 309.6 mg g−1. Effects of initial pH values, co-existed ions and humic acid on the adsorption performance of functionalized MIL-53(Fe) were investigated. The adsorption kinetics fitted well with pseudo-second order model and the adsorption isotherms matched Langmuir model, which suggested that the adsorption process was dominant by chemisorption and the adsorption surface was homogenous. Additionally, adsorption thermodynamics showed that the adsorption process of TCN on MIL-53(Fe) series were spontaneous and endothermic. More importantly, the functionalized MIL-53(Fe) demonstrated excellent recyclability and the detailed adsorption mechanism was discussed. Therefore, this work provided a strategy for fabrication of efficient MOFs-based adsorbent for antibiotic-containing wastewater treatment.

Tetracycline exposure shifted microbial communities and enriched antibiotic resistance genes in the aerobic granular sludge

The aerobic granular sludge with larger size and more compact spherical structure generally shows excellent performance in antibiotic removal, yet little is known about the long-term effect of environmentally-relevant concentration (μg/L) of antibiotics on the proliferation of antibiotic resistance genes (ARGs) and microbial community in aerobic granules. Herein, a sequencing batch reactor (SBR) was set up with dosing different concentrations (0–500 μg/L) of tetracycline to investigate its influences on microbial communities and ARG levels in aerobic granular sludge. Results show that the bioreactor could effectively remove chemical oxygen demand (COD), nitrogen, and tetracycline during the long-term operation. The quantitative polymerase chain reaction (qPCR) analysis shows that tetracycline at μg/L level could greatly enhance the absolute and relative abundances of tetA, sulII, and blaTEM-1 in the effluent and aerobic granules, indicating tetracycline could serve as a selection pressure on the development of ARGs corresponding to different types of antibiotics in aerobic granules. Pearson's correlation analysis also implies that sulII and blaTEM-1 were correlated strongly with tetA. Moreover, the presence of tetracycline altered the microbial communities and diversity of the effluent and aerobic granules in the bioreactor. These findings would advance our understanding of the proliferation and development of ARGs in aerobic granules under tetracycline pressure and serve as a foundation to guide the application of aerobic granular sludge for treatment of antibiotic-containing wastewater.

Response of antibiotic resistance to the co-existence of chloramphenicol and copper during bio-electrochemical treatment of antibiotic-containing wastewater

Concerns have been raised regarding co-selection for antibiotic resistance among microorganisms exposed to antibiotics and metals. As a promising approach for treating antibiotics and heavy metal-containing wastewater, a bio-electrochemical system (BES) can be used for antibiotic and heavy metal removal. This study determined the fate of antibiotic resistance genes (ARGs) in a BES when exposed to chloramphenicol (CAP) and Cu2+. The ARGs encoding the efflux pump (cmlA, floR, and tetC), the class 1 integron integrase-encoding gene, and the sul1 gene were analyzed. The results indicated that the co-existence of CAP and different concentrations of Cu2+ had significant influence on the relative abundances of the ARGs. The changes in the bacterial community structure and the results of a quantitative correlation analysis between the bacterial community and the ARGs confirmed that the shift in the potential hosts was the key reason for the changes of the ARGs. This study sheds new light on the mechanisms of ARGs variations in BES under the co-selection pressure of antibiotics and heavy metals.

Highly flexible, mesoporous structured, and metallic Cu-doped C/SiO2 nanofibrous membranes for efficient catalytic oxidative elimination of antibiotic pollutants.

The development of inorganic membranous catalysts with both large mesopores and superb flexibility is extremely favorable for the enhancement of their catalytic oxidation activity for the degradation of antibiotic pollutants in wastewater via sulfate radical-based advanced oxidation processes; however, there still exists a huge challenge for inorganic materials to simultaneously realize these two properties. Herein, metallic copper-doped carbon/silica nanofibrous membranes (Cu@C/SiO2 NFMs) with large mesopores, superb flexibility, and robust mechanical strength were fabricated through a sol-gel electrospinning and subsequent in situ carbonization reduction method. The synthesized Cu nanoparticles were homogeneously distributed throughout the mesoporous C/SiO2 nanofiber matrix, which enabled the resultant Cu@C/SiO2 NFMs to be applied as heterogeneous catalysts, and their catalytic performance was systematically assessed through activating persulfate for the elimination of tetracycline hydrochloride (TCH) in water. The fabricated Cu@C/SiO2 NFMs provided outstanding catalytic performance towards TCH with a high removal efficiency of 95% in 40 min and a rapid removal speed of 0.054 min-1. Moreover, the membranes could be facilely recycled through being directly separated from water without any post-processing. Such a facile strategy for preparing mesoporous and flexible metal-doped inorganic nanofibrous membranes may offer novel insights for designing new types of heterogeneous catalysts for antibiotic-containing wastewater treatment or other potential applications.

Cobalt oxide loaded graphitic carbon nitride as adsorptive photocatalyst for tetracycline removal from aqueous solution

The treatment of antibiotic-containing wastewater is of great importance due to the potential threats of antibiotics to human and the ecosystem. We reported the preparation of cobalt oxide loaded graphitic carbon nitride (CoO/g-C3N4) by an impregnation-calcination method for tetracycline (TC) removal from aqueous solution. The developed CoO/g-C3N4 exhibited high adsorption capacity and fast adsorption kinetic for TC due to the complexation of TC with surface loaded CoO. In particular, 7%CoO/gC3N43 sample presented a maximum TC adsorption capacity of 391.4 mg g−1. It was found that Langmuir and pseudo-second order kinetic models fitted TC adsorption process well. Further photocatalytic studies showed that CoO loaded g-C3N4 was active for TC photodegradation, although the photocatalytic reaction rate constant was lower than that of native g-C3N4. CoO nanoparticles loading on g-C3N4 played the major role of adsorption sites rather than cocatalyst for photocatalysis. We believe that the developed CoO/g-C3N4 could be a potential adsorptive photocatalyst for antibiotic pollutants removal from wastewater.

Response of chloramphenicol-reducing biocathode resistome to continuous electrical stimulation

Understanding the fate of overall antibiotic resistance genes (ARGs) during the biological treatment of antibiotic containing wastewater is a central issue for the water ecological safety assessment. Although the microbial electrode-respiration based biotransformation process could significantly detoxify some antibiotic contaminants, e.g. chloramphenicol (CAP), the response of CAP-reducing biocathode microbiome and resistome to continuous electrical stimulation, especially ARGs network interactions, are poorly understood. Here, using highthroughput functional gene array (GeoChip v4.6) and Illumina 16S rRNA gene MiSeq sequencing, the structure, composition, diversity and network interactions of CAP-reducing biocathode microbiome and resistome in response to continuous electrical stimulation were investigated. Our results indicate that the CAP bioelectroreduction process could significantly accelerate the elimination of antibacterial activity of CAP during CAP-containing wastewater treatment compared to the pure bioreduction process. Continuous electrical stimulation could obviously alter both the microbiome and resistome structures and consistently decrease the phylogenetic, functional and overall ARGs diversity and network complexity within the CAP-reducing biofilms. The relative abundances of overall ARGs and specific CAP resistance related major facilitator superfamily (MFS) transporter genes were significantly negatively correlated with the reduction efficiency of CAP to inactive antibacterial product AMCl (partially dechlorinated aromatic amine), which may reduce the ecological risk associated with the evolution of multidrug-resistant bacteria and ARGs during antibiotic-containing wastewater treatment process. This study offers new insights into the response of an antibiotic reducing biocathode resistome to continuous electrical stimulation and provides useful information on the assessment of overall ARGs risk for the bioelectrochemical treatment of antibiotic contaminants.

Study on the interaction mechanism between cefradine and Chlamydomonas reinhardtii in water solutions under dark condition

Our research investigated the hormesis effect of cefradine on the specific growth rates (μ) of single-celled algae (Chlamydomonas reinhardtii) from aqueous solutions. We found the specific growth rate of C. reinhardtii slightly increased with cefradine concentrations within the range 0.5–10 mg/L. Effects of algae density, initial solution pH, and temperature on the adsorption batch assays were investigated. The optimum conditions for cefradine adsorption occurred at a density of 5 × 106 algae cells/mL, a solution pH of 7.0, and a temperature of 25.0 °C. A Box–Behnken design was employed to evaluate correlations between influential factors and cefradine adsorption. The results showed a significant interaction between algae density and temperature. The maximum removal rate could reach 50.13% under the optimal conditions. Additionally, the adsorption mechanisms were explored through Langmuir and Freundlich isotherm equations, adsorption kinetics, and thermodynamics. The results suggested that the adsorption process was monolayer, spontaneous, and endothermic with an increase in randomness at the algae–solution interface, which followed a pseudo-second-order model. All the data indicated that the alga performed a better removal capacity in the antibiotic-containing wastewater treatment process. This study lays the groundwork for a better understanding of the interaction mechanism between cefradine and Chlamydomonas reinhardtii in water solutions under dark condition.