Removal of enrofloxacin using Eichhornia crassipes in microcosm wetlands.

The global consumption of antibiotics leads to their possible occurrence in the environment. In this context, nature-based solutions (NBS) can be used to sustainably manage and restore natural and modified ecosystems. In this work, we studied the efficiency of the NBS free-water surface wetlands (FWSWs) using Eichhornia crassipes in microcosm for enrofloxacin removal. We also explored the behavior of enrofloxacin in the system, its accumulation and distribution in plant tissues, the detoxification mechanisms, and the possible effects on plant growth. Enrofloxacin was initially taken up by E. crassipes (first 100 h). Notably, it accumulated in the sediment at the end of the experimental time. Removal rates above 94% were obtained in systems with sediment and sediment + E. crassipes. In addition, enrofloxacin was found in leaves, petioles, and roots (8.8-23.6 µg, 11-78.3 µg, and 10.2-70.7 µg, respectively). Furthermore, enrofloxacin, the main degradation product (ciprofloxacin), and other degradation products were quantified in the tissues and chlorosis was observed on days 5 and 9. Finally, the degradation products of enrofloxacin were analyzed, and four possible metabolic pathways of enrofloxacin in E. crassipes were described.

Multivariate optimization of a dispersive liquid-liquid microextraction method for the determination of six antiparasite drugs in kennel effluent waters by using second-order chromatographic data.

Six veterinary active ingredients (imidacloprid, albendazole, fenbendazole, praziquantel, fipronil and permethrin) were extracted and quantified by liquid chromatography with diode array detection in water samples from a wetland system used for the treatment of waste from a dog breeding plant. Response surface methodology, based on least-squares and artificial neural networks modelling, was applied for the optimization of a dispersive liquid-liquid microextraction (DLLME) procedure. Firstly, two experimental designs were built for screening and optimization, respectively. Then, the desirability function was implemented for the simultaneous optimization of the six recoveries (chromatographic areas of the six compounds). The optimum conditions were: 600 µL of acetone (dispersive solvent), 670 µL of dichloromethane (extractant solvent) and 0.6 min of vortex mixing. The preconcentration factor was 37.5. Then, in order to identify and quantify the six drugs, second-order calibration with MCR-ALS modeling of HPLC-DAD data was implemented attaining successful results. The limits of quantification were 4 ng mL-1 for imidaclopril, albendazole and fenbendazole; 8 ng mL-1 for praziquantel and fipronil; and 26 ng mL-1 for permethrin. The developed method allowed the quantitation of the target analytes, even in the presence of unexpected compounds from dirty water samples. The following maximum levels of veterinary drugs were found (in ng mL-1): imidaclopril, 7; albendazole, 46; fenbendazole, 21; praziquantel, 29; fipronil, 29 and permethrin, 217.

Horizontal subsurface flow constructed wetland for tertiary treatment of dairy wastewater: Removal efficiencies and plant uptake.

There are different physicochemical and biological methods to treat effluents. However, their efficiency is not enough to meet the effluents discharge limits. For this reason, it could be possible to employ a polished treatment. A suitable alternative for this goal could be constructed wetlands (CWs). The aim of the present research was to evaluate contaminants removal efficiency of a pilot scale horizontal subsurface flow constructed wetland (HSSFW) for tertiary treatment of dairy wastewater. A vegetation study was also conducted in order to determine the role of plants on nutrient removal. A pilot scale HSSFW planted with Typha domingensis was built in a dairy factory, after the biological treatment. The substrate used was river gravel. During a seven-month research period, thirty-two samples (influent and effluent) were taken and analyzed to determine physicochemical and microbiological parameters as well as removal efficiencies. Biomass, TP, TKN and organic matter content in plants was determined at the beginning and end of the monitoring period. Suspended solids showed significant differences between inlet and outlet, with a mean removal efficiency of 78.4%. For BOD and COD, mean removal efficiencies were respectively 57.9 and 68.7%. Removal percentages for TKN, Nitrates and TP were lower than other parameters (25.7%, 47.8% and 29.9%, respectively). Fecal Coliform bacteria decreased one order of magnitude in final effluent. In the case of Escherichia coli and Pseudomona aeruginosa results were variable. Total biomass increased 4.6 times at the end of the monitoring period. The study of plants indicated its important contribution in terms of contaminant uptake and retention. HSSFW would be an advisable alternative as a tertiary treatment of dairy wastewater.

Chromium bioaccumulation: comparison of the capacity of two floating aquatic macrophytes.

The capacity of Salvinia herzogii and Pistia stratiotes to remove Cr (III) from water and their behaviour at different Cr (III) concentrations were studied in outdoor experiments. Cr distribution in aerial parts and roots with time and the possible mechanisms of Cr uptake were analyzed. Both macrophytes efficiently removed Cr from water at concentrations of 1, 2, 4 and 6 mgCrL(-1). S. herzogii was the best adapted species. At a greater initial concentration, greater bioaccumulation rates were observed. Root Cr uptake was a rapid process that was completed within the first 24h. Cr uptake through direct contact between the leaves and the solution is the main cause of the increase of Cr in the aerial parts, Cr being poorly translocated from the roots to the aerial parts. Both mechanisms were fast processes. The Cr uptake mechanism involves two components: a fast component and a slow one. The former occurs mainly due to the roots and leaves adsorption and is similar for both species. The slow component is different for each species probably because in P. stratiotes a Cr precipitation occurs induced by the roots.