The presence of antibiotic-resistant (AR) E. coli, antibiotic resistance genes (ARGs), and intI1 was investigated in different treatment stages, comparing a conventional activated sludge wastewater treatment plant (WWTP) with a nature-based system in a decentralised area comprising upflow anaerobic sludge blanket reactors (UASBs), constructed wetlands (CWs), and an ultraviolet (UV) disinfection unit. Furthermore, the efficacy of UV irradiation and chlorination in the removal of AR E. coli, ARGs and intI1 from the effluent of CWs and the secondary treated effluent of the conventional WWTP was investigated. The study found that the natural system decreased AR E. coli by 3.7–4.1 log and ARGs by 0.80–2.3 log. In contrast, the conventional WWTP reduced AR E. coli by 2.5–2.8 log and ARGs by 1.9–3.2 log. CWs enhance ARB removal through longer hydraulic retention times, plant–microbe interactions, and diverse ecological processes, offering advantages over conventional WWTPs. UV treatment with doses of 70 mJ/cm² and 100 mJ/cm² effectively removed AR E. coli but increased their percentage, indicating higher resistance to UV. However, these UV doses were ineffective in removing ARGs. Chlorination at doses of 35–50 mg Cl₂/L·min effectively inactivated antibiotic-resistant bacteria (ARB) in wastewater. However, inadequate doses increased the prevalence of antibiotic-resistant strains and facilitated horizontal gene transfer via natural transformation. A high chlorine dose of 220 mg Cl₂/L·min was insufficient to remove ARGs from secondary treated and CW effluents. These results highlight the persistence of ARGs despite aggressive chlorination and high UV disinfection doses, emphasizing the need for complementary or advanced treatment methods.

Non-steroidal anti-inflammatory drugs (NSAIDs) and endocrine disruptors (EDCs) are among the most important categories of contaminants of emerging concern (CECs), and many advanced technologies have been developed for their elimination from water and wastewater, including nano-zero valent iron (nZVI). This study investigates the performance of nZVI synthesized from green tea extracts and incorporated into a cationic resin (R-nFe) in the removal of four selected NSAIDs, namely ibuprofen (IBU), naproxen (NPX), diclofenac (DCF), and ketoprofen (KFN), and an EDC, namely bisphenol A (BPA). Column experiments were conducted to evaluate the effect of various operating parameters, including initial CECs concentration, contact time, pH, addition, and dose of sodium persulfate (PS). To the authors’ knowledge, this is the first time that environmentally friendly produced nZVI has been combined with PS in column experiments for the removal of CECs from wastewater. With a contact time of 2.2 min, PS = 1 mM, and influent pH = 3.5, 27–72% of IBU, 70–99% of NPX, 70–95% of DCF, 28–50% of KFN, and 61–91% of BPA were removed during a 12-day operation of the system, while the initial concentration of each substance was 5 μg/L. Therefore, it is anticipated that the proposed system could be a promising post-treatment technology for the removal of CECs from wastewater.

Nano zerovalent iron (nZVI), produced from green tea extracts, was incorporated in a cation exchange resin (R-nFe) to investigate its performance regarding the removal of four non-steroidal anti-inflammatory drugs (NSAIDs): ibuprofen (IBU), naproxen (NPX), ketoprofen (KTP) and diclofenac (DCF). The effect of contact time, NaCl pretreatment, pH, R-nFe dose, the role of the supporting material, the initial concentration of pollutants, and the combined effect of nZVI with oxidative reagents was assessed through a series of batch experiments. According to the results, the best removal efficiencies obtained for DCF and KTP were 86% and 73%, respectively, at 48 h of contact time with NaCl pretreated R-nFe at a dose of 15 g L⁻¹ and a pH of 4. The maximum removal efficiency for NPX was 90% for a contact time of 60 min with PS 1 mM and a pH of 3, which was quite similar to the experiment with a greater contact time of 48 h without PS addition. The maximum IBU removal was 70%; this was reached at pH 3, with a contact time of 30 min and R-nFe 15 g L⁻¹. To the authors’ best knowledge, this is the first study investigating the utilization of nZVI, produced from leaf extracts and incorporated into a cationic exchange resin, to remove NSAIDs from water.