Degradation of high concentrations of azithromycin when present in a high organic content wastewater by using a continuously fed laboratory-scale UASB bioreactor

Acidic-thermal coupled degradation of tylosin by using magnetic sulfonated resins under microwave irradiation

Acidic- and alkalic-hydrolyses are selective in breaking functional bonds and falling off pharmacological moieties of antibiotics in production wastewater in comparison with advanced oxidation processes. Elevating temperature can accelerate hydrolytic kinetics and improve efficiency. In this work, magnetic sulfonated polypropylene resin (Fe3O4@PS-S) composites were reported for acidic-thermal hydrolysis of tylosin by employing the acidic feature of sulfonic group, the dielectric effect of resin, and the magnetic-loss effect of magnetite under microwave irradiation. As observed, a rapid and complete mitigation 100 mg/L of tylosin was achieved within 15 min by the catalysts. Acidic cleavage of tylosin was fulfilled by sulfonic groups in the composites, and microwave thermal accelerated the hydrolysis reactions due to the dielectric and magnetic-loss effects. Differentiating the dielectric and magnetic-loss effects through electromagnetic analyses indicated that the latter contributed more in converting microwave energy to heat. The interactions under multiple operational conditions were quantitatively fitted using the Behnajady model and visually demonstrated, which indicated that a synergic effect of microwave thermal- and acidic-hydrolyses contributed to the efficient mitigation of tylosin. The transformation products were identified and the pathways were supposed. Cleaving deoxyaminosugars groups and destructing lactone structures led to reduced antibacterial potential and toxicity reduction. The acute toxicity of tylosin and transformation products to fish, daphnia, and green algae were all classified as non-toxic. This work suggested that this synergistic acid-thermal hydrolytic method is attractive and promising in pretreating tylosin production wastewater in field.

Azithromycin removal from water via adsorption on drinking water sludge-derived materials: Kinetics and isotherms studies

In this study, we utilized drinking water treatment sludge (WTS) to produce adsorbents through the drying and calcination process. These adsorbents were then evaluated for their ability to remove azithromycin (AZT) from aqueous solutions. The L-500 adsorbent, derived from the calcination (at 500°C) of WTS generated under conditions of low turbidity in the drinking water treatment plant, presented an increase in the specific surface area from 70.745 to 95.471 m2 g-1 and in the total pore volume from 0.154 to 0.211 cm3 g-1, which resulted in a significant AZT removal efficiency of 65% in distilled water after 60 min of treatment. In synthetic wastewater, the rate of AZT removal increased to 80%, in comparison, in a real effluent of a municipal wastewater treatment plant, an AZT removal of 56% was obtained. Kinetic studies revealed that the experimental data followed the pseudo-second-order model (R2: 0.993-0.999, APE: 0.07-1.30%, and Δq: 0.10-2.14%) suggesting that chemisorption is the limiting step in the adsorption using L-500. This finding aligns with FTIR analysis, which indicates that adsorption mechanisms involve π-π stacking, hydrogen bonding, and electrostatic interactions. The equilibrium data were analyzed using the nonlinear Langmuir, Freundlich, and Langmuir-Freundlich isotherms. The Langmuir-Freundlich model presented the best fitting (R2: 0.93, APE: 2.22%, and Δq: 0.06%) revealing numerous interactions and adsorption energies between AZT and L-500. This adsorbent showed a reduction of 19% in its AZT removal after four consecutive reuse cycles. In line with the circular economy principles, our study presents an interesting prospect for the reuse and valorization of WTS. This approach not only offers an effective adsorbent for AZT removal from water but also represents a significant step forward in advancing sustainable water treatment solutions within the framework of the circular economy.

Anaerobic removal of contaminants of emerging concern in municipal wastewater: Eco-toxicological risk evaluation and strategic selection of optimal treatment

In the last decades, the interest for anaerobic process as a mainstream treatment of municipal wastewater increased due to the development of high-rate anaerobic bioreactors able to achieve removal kinetics comparable to the aerobic ones. Moreover, they have the additional advantages of energy production, nutrient recovery and reduced excess sludge yield, which are interesting features in the frame of sustainability wastewater treatment goals. These appealing factors increased the research demand to evaluate the potential of the anaerobic removal for contaminants of emerging concern (CECs) in municipal wastewater. However, despite the growing interest for the subject, literature is still fragmentary and reviews are mainly focused on specific technologies and target compounds or groups of compounds. We propose this review with the main objectives of presenting the state of knowledge, the performances of anaerobic systems for CECs' removal and, more important, to give the reader guidelines for optimal treatment selection. In the first part, a general overview of the investigated technologies at different scale, with a special focus on the recently proposed enhancements, is presented. Collected data are analysed to select the target CECs and the analysis results employed to define the optimal technological solution for their removal. A first novelty element of the paper is the original procedure for contaminant selection consisting of a risk assessment tool for CECs, based on their frequency of detection, concentration and potential for biosorption in wastewater treatment plants. Data of selected target CECs are combined with compound and technology performance data to implement a flowchart tool to evaluate the optimal treatment strategy, which constitute another, even more important, novelty element of this study.

Catalytic Activation of Hydrogen Peroxide Using Highly Porous Hydrothermally Modified Manganese Catalysts for Removal of Azithromycin Antibiotic from Aqueous Solution

Hydrogen peroxide catalytic activation holds great promise in the treatment of persistent pollutants. In this study, the novel Mn-Acacair/Al, Mn-Acacarg/Al and Mn-BTCarg/Al catalysts, supported on Al2O3, were applied for rapid hydrogen peroxide activation and azithromycin antibiotic removal. The catalysts were prepared by the calcination-hydrothermal method under air or argon atmosphere. The characterization confirmed that the modification of manganese with acetylacetonate and benzene-1,3,5-tricarboxylic acid (H3BTC) O-donor ligands highly improves the catalyst porosity, amorphousity, and abundance of coordinately unsaturated sites, which facilitate the generation of reactive oxygen species. The hydrogen peroxide activation and azithromycin removal reached 98.4% and 99.3% after 40 min using the Mn-BTCarg/Al catalyst with incredible stability and reusability. Only a 5.2% decrease in activity and less than 2% manganese releasing in solutions were detected after five regeneration cycles under the optimum operating conditions. The removal intermediates were identified by LC-MS/MS analysis, and the pathways were proposed. The hydroxylation and decarboxylation reactions play a key role in the degradation reaction.

Azithromycin Adsorption onto Different Soils

The antibiotic azithromycin (AZM) is one of the most persistent in the environment, with potential to cause serious health and environmental problems. As some polluting discharges containing this antibiotic can reach the soil, it is clearly relevant determining the ability of soils with different characteristics to retain it. In this research, AZM adsorption and desorption were studied for a variety of soils, using batch-type experiments. The results show that, at low doses of antibiotic added (less than or equal to 50 µmol L−1), the adsorption always reached 100%, while when higher concentrations were added (between 200 and 600 µmol L−1) the highest adsorption corresponded to soils with higher pH values. Adsorption data were fitted to the Linear, Langmuir and Freundlich models, with the latter showing the best fit, in view of the determination coefficient. No desorption was detected, indicating that AZM is strongly adsorbed to the soils evaluated, suggesting that the risks of environmental problems due to this contaminant are minimized for these edaphic media. These results can be considered relevant with respect to risk assessment and possible programming of measures aimed at controlling environmental contamination by emerging contaminants, especially from the group of antibiotics, and in particular from AZM.

Anaerobic recalcitrance in wastewater treatment: A review

Anaerobic treatment is applied as an alternative to traditional aerobic treatment for recalcitrant compound degradation. This review highlighted the recalcitrant compounds in wastewaters and their pathways under aerobic and anaerobic conditions. Forty-one recalcitrant compounds commonly found in wastewater along with associated anaerobic removal performance were summarized from current research. Anaerobic degradability of wastewater could not be appropriately evaluated by BOD/COD ratio, which should only be suitable for determining aerobic degradability. Recalcitrant wastewaters with a low BOD/COD ratio may be handled by anaerobic treatments after the adaption and provision of sufficient electron donors. Novel indicator characterizing the anaerobic recalcitrance of wastewater is called for, essential for emergent needs to resource recovery from high-strength recalcitrant wastewater for fulfilling appeals of circular bioeconomy of modern societies.