Pharmaceuticals are present in the environment from anthropogenic pollution sources, leading to groundwater contamination when reaching urban aquifers. Once in the subsurface, their fate depends on the hydrochemical processes and environmental conditions within the aquifer. In this context, this study investigates how different redox and temperature conditions affect the natural attenuation of pharmaceuticals in the subsurface. Batch experiments were conducted under oxic and suboxic (i.e., up to nitrate reduction) conditions and at two temperatures (25 °C and 35 °C). The controlled conditions achieved with parallel batch reactor systems allowed us a systematic investigation of the processes and factors involved in the fate of ten pharmaceuticals (atenolol, citalopram, climbazole, irbesartan, lamotrigine, sitagliptin, carbamazepine, metoprolol, trimethoprim, and venlafaxine), providing insights into the mechanisms governing their attenuation. The results showed that oxic conditions were highly effective in reducing pharmaceuticals concentrations, achieving up to 91 % attenuation for irbesartan, followed by citalopram (90 %), climbazole (77 %), sitagliptin (76 %) and metoprolol (75 %). Atenolol and climbazole were also attenuated regardless of redox conditions. High temperatures increased the total removal of citalopram, irbesartan, sitagliptin, and trimethoprim by 5–12 %, while slightly enhancing the sorption affinity of carbamazepine, irbesartan, and atenolol by 5 %. However, trimethoprim, carbamazepine, and lamotrigine were the most persistent compounds, with average removal rates of 6 %, 15 %, and 24 %, respectively. Overall, more than half of the targeted pharmaceuticals showed significant average removal (>60 %), highlighting the influence of the processes involved in groundwater on the natural attenuation of these compounds. Sorption seemed to be the primary process contributing to the target pharmaceuticals attenuation in oxic conditions, while biodegradation played a secondary role, particularly for atenolol and metoprolol. These findings contribute to improve our understanding of the behaviour of pharmaceuticals in aquatic environment and thus to improve management practices for better water quality.

Green infrastructure drainage systems are innovative treatment units that capture and treat stormwater. Unfortunately, highly polar contaminants remain challenging to remove in conventional biofilters. To overcome treatment limitations, we assessed the transport and removal of stormwater vehicle-related organic contaminants with persistent, mobile, and toxic (in short: PMTs) properties, such as 1H-benzotriazole, NN'-diphenylguanidine, and hexamethoxymethylmelamine (PMT precursor), using batch experiments and continuous-flow sand columns amended with pyrogenic carbonaceous materials, like granulated activated carbon (GAC) or wheat-straw derived biochar. Our results indicated that all investigated contaminants were subjected to nonequilibrium interactions in sand-only and geomedia-amended columns, with kinetic effects upon transport. Experimental breakthrough curves could be well described by a one-site kinetic transport model assuming saturation of sorption sites, which we inferred could occur due to dissolved organic matter fouling. Furthermore, from both batch and column experiments, we found that GAC could remove contaminants significantly better than biochar with higher sorption capacity and faster sorption kinetics. Hexamethoxymethylmelamine, with the lowest organic carbon-water partition coefficient (K_OC) and largest molecular volume among target chemicals, exhibited the lowest affinity in both carbonaceous adsorbents based on estimated sorption parameters. Results suggest that sorption of investigated PMTs was likely driven by steric and hydrophobic effects, and coulombic and other weak intermolecular forces (e.g., London–van der Waals, H-bonding). Results from extrapolating our data to a 1-m depth geomedia-amended sand filter suggested that GAC and biochar could enhance the removal of organic contaminants in biofilters and last for more than one decade. Overall, our work is the first to study treatment alternatives for NN'-diphenylguanidine and hexamethoxymethylmelamine, and contributes to better PMT contaminant removal strategies in environmental applications.

A learning-based strategy that uses support vector machines and k nearest neighbours is proposed for locating the faulted zone in radial power systems, specifically in distribution networks. The main goal is to reduce the multiple estimation of the fault location, inherent in those methods that use single end measurements. A selection of features obtained from the fundamentals of voltages and currents, measured at the power substation, are analysed and used as inputs of the proposed zone locator. Performance of several combinations of these features considering all fault types, different short-circuit levels and variation of the fault resistance, and the system load is evaluated. An application example illustrates the high precision to locate the faulted zone, obtained with the proposed methodology. The proposal provides appropriate information for the prevention and opportune attention of faults, requires minimum investment and overcomes the multiple estimation problem of the classic impedance based methods.