Phytoremediation of levonorgestrel in aquatic environment by hydrophytes

Sorption of levonorgestrel on polyethylene, polystyrene and polypropylene microplastics

Sorption studies involving microplastics (MPs) are essential to understand the mechanisms implicated in contaminant retention. In this research, a complete study of the sorption behaviour of a hormonal contraceptive -levonorgestrel- in MPs of different composition in two distinct matrices was performed, using high-performance liquid chromatography coupled to a UV detector for the determination of levonorgestrel. Characterization of the studied MPs was achieved by X-ray diffraction and differential scanning calorimetry, and Fourier-transformed infrared spectroscopy. Kinetic and isotherm studies were performed using a batch design under controlled conditions: 500 mg of MPs pellets of 3-5 mm diameter, agitation at 125 rpm, and 30 °C. The comparison of results in ultrapure water and artificial seawater, revealed changes in sorption capacity, and the predominant sorption mechanisms involved. Overall, all studied MPs showed sorption affinity towards levonorgestrel, being low-density polyethylene the one with the highest sorption capacity in ultrapure water and polystyrene in seawater.

Bio-removal of emerging pollutants by advanced bioremediation techniques

This review highlights the relevance of bioremediation techniques for the removal of emerging pollutants (EPs). The EPs are chemical or biological pollutants that are not currently monitored or regulated by environmental authorities, but which can enter the environment and cause harmful effects to the environment and human health. In recent times, an ample range of EPs have been found in water bodies, where they can unbalance ecosystems and cause negative effects on non-target species. In addition, some EPs have shown high rates of bioaccumulation in aquatic species, thus affecting the safety and quality of seafood. The negative impacts of emerging pollutants, their wide distribution in the environment, their bioaccumulation rates, and their resistance to wastewater treatment plants processes have led to research on sustainable remediation. Remediation techniques have been recently directed to advanced biological remediation technologies. Such technologies have exhibited numerous advantages like in-situ remediation, low costs, eco-friendliness, high public acceptance, and so on. Thus, the present review has compiled the most recent studies on bioremediation techniques for water decontamination from emerging pollutants to extend the current knowledge on sustainable remediation technologies. Biological emerging contaminants, agrochemicals, endocrine-disrupting chemicals, and pharmaceutical and personal care products were considered for this review study, and their removal by bioremediation techniques involving plants, bacteria, microalgae, and fungi. Finally, further research opportunities are presented based on current challenges from an economic, biological, and operation perspective.

Antibiotic fate in an artificial-constructed urban river planted with the algae Microcystis aeruginosa and emergent hydrophyte

The behavior and removal of six antibiotics, that is, azithromycin, clarithromycin, sulfathiazole, sulfamethoxazole, ciprofloxacin, and tetracycline, in an artificial-controllable urban river (ACUR) were investigated. The ACUR was constructed to form five artificial eco-systems by planting three emergent hydrophytes and Microcystis aeruginosa: (1) Control; (2) MA: M. aeruginosa only; (3) MA-J-C: M. aeruginosa combined with Juncus effusus and Cyperus alternifolius; (4) MA-C-A: M. aeruginosa combined with C. alternifolius and Acorus calamus L.; (5) MA-A-J: M. aeruginosa combined with A. calamus L. and J. effusus. The MA-C-A system achieved the best removal of azithromycin and clarithromycin after 15-day test with the final concentrations 0.92 and 0.83 μg/L. The contents of ciprofloxacin and tetracycline in sediment were highest, up to 1453 and 1745 ng/g. The antibiotic plant bioaccumulation was higher in roots rather than the shoots (stem and leaves). No target antibiotics were detected in algae cells. The combination of hybrid hydrophytes had a certain effect on the removal of antibiotics, and thus selecting appropriate hydrophytes in urban rivers could greatly improve water quality. The overall removal of six antibiotics was greatly improved by the ACUR containing the hybrid hydrophytes and the algae, indicating a synergistic effect on antibiotic removal. PRACTITIONER POINTS: Controllable-mobile artificial eco-systems were developed with emergent hydrophytes and M. aeruginosa. The M. aeruginosa + Cyperus alternifolius + Acorus calamus L. system removed azithromycin and clarithromycin most at the end of tests. Emergent hydrophytes and M. aeruginosa have a synergistic effect on the removal of antibiotics. The combination of emergent hydrophytes did play an important role in the removal of antibiotics. The artificial eco-systems containing the hybrid hydrophytes and the algae could greatly improve the overall removal of antibiotics.

Migration of antibiotic ciprofloxacin during phytoremediation of contaminated water and identification of transformation products

Phytoremediation is an effective and environmentally friendly approach to treat antibiotic contaminated water, however, the mechanisms of migration and transformation of antibiotics in plant tissues are still far from clear. In this study, the floating macrophyte Eichhornia crassipes was exposed to a series of antibiotic ciprofloxacin (CIP) concentrations. The results showed that the CIP was taken up and accumulated in the roots, which were the major accumulative tissue. CIP content increased with lipid content. During cultivation, the root bioconcentration factor (RCF) gradually increased. The average CIP content detected in aerial parts was 12.80 μg g^-1, an order of magnitude lower than in the roots. At low CIP concentrations, the highest leaf bioconcentration factor (LCF) and transfer factor (TF) indicated highly efficient translocation from roots to aerial parts. The soluble protein growth rate of leaves, which is associated with metabolic activity, increased following CIP exposure. Overall, eight major transformation products in E. crassipes tissues were identified, and three possible transformation pathways were proposed involving the processes of desethylation, dehydroxylation, oxidation, hydroxylation and cleavage of the piperazine and quinoline rings. These findings could prove beneficial for improving the management or amelioration methods used for treating water contaminated with antibiotics.

Removal of the endocrine disruptors ethinyl estradiol, bisphenol A, and levonorgestrel by subsurface constructed wetlands

The present work aimed to evaluate the removal efficiency of the endocrine disruptors ethinyl estradiol (EE2), the progestin levonorgestrel (LNG), and bisphenol A (BPA), considered to be contaminants of major concern, by using four laboratory scale constructed wetlands (CW) - three containing gravel as support media, one cultivated with Cyperus isocladus (WL1), other with Eichhornia crassipes (WL3), and one without macrophyte (WL2). The fourth unit contained gravel and bamboo charcoal as support medium, also cultivated with Cyperus isocladus (WLC). Two hydraulic retention times (HRT) were tested, 2 and 4 days. Average removals ranged from 9.0 to 95.6% for EE2, from 29.5 to 91.2% for BPA and from 39.1 to 100.0% for LNG. The results showed that the most efficient CW for removal of EE2 and BPA was WLC, and for LNG removal was WL3. The 2 days HRT was statistically more efficient in removing EE2, and the 4 days HRT was more efficient in the LNG removal. The other endocrine disruptors and concentration ranges were not influenced by HRT. It was concluded that WLC was the most suitable CW for removal of these three compounds, and it possibly is efficient also for the removal of other endocrine disruptors with similar physical-chemical characteristics.

Assessment of endocrine disruptor effects of levonorgestrel and its photoproducts: Environmental implications of released fractions after their photocatalytic removal

The presence of levonorgestrel (LNG) in water bodies via direct discharge and human excretion has been reported worldwide, but its effects on the reproduction of aquatic species and humans are still unknown. Owing to its recalcitrant properties, LNG is not completely removed during wastewater treatment plants, and many species may be exposed to low traces of this compound from discharged effluents. Thus, in this study, a photocatalytic process for removing LNG along with screening of endocrine disruptor effects for risk assessment was applied. Although the removal rate of LNG by ultraviolet C (UV-C) radiation was >90%, reproductive toxicity testing using the BeWo cell line exposed to LNG and its degraded fraction showed the reduced production of basal human chorionic gonadotropin hormone (β-hCG) by more than 73%, from 8.90 mIU mL^-1 to <2.39 mIU mL^-1, with both LNG and the degraded fraction. β-hCG hormone has been implicated in the viability of trophoblastic cells during the first trimester of pregnancy; therefore, degraded fractions and waterborne LNG may affect reproduction in some aquatic species and humans with low level of exposure.