Column Experiments on Sorption Coefficients and Biodegradation Rates of Selected Pharmaceuticals in Three Aquifer Sediments

Abstract

The presence of pharmaceuticals in the environment, and in groundwater, has been recognized as a great environmental concern. Biodegradation and sorption are the main processes leading to the removal of contamination from the water phase. The aim of this study was to determine the transport processes of selected pharmaceuticals (antipyrine, atenolol, carbamazepine, caffeine, diclofenac, ketoprofen, sulfamethoxazole) in selected sediments (coarse sand, medium sand, sandy loam) in laboratory experiments. Moreover, the impact of flow velocities on the sorption and degradation rates of the selected compounds was studied. Column experiments were performed at three flow velocities, under abiotic and biotic conditions, applying conservative (bromide) and reactive tracers (pharmaceuticals). From the breakthrough curves, retardation factors and degradation rates were determined and the influence of variable flow conditions on transport parameters was evaluated. Low observed concentrations and recoveries of atenolol indicated a strong influence of sorption on its transport. Diclofenac, caffeine, and carbamazepine were also affected by sorption but to a lesser extent. Sulfamethoxazole, ketoprofen, and antipyrine were recovered nearly completely, indicating an almost conservative transport behavior. Biodegradation was small for all the compounds, as the results from biotic and abiotic column experiments were similar. Transport of the tested pharmaceuticals was not influenced by different flow velocities, as similar modelled degradation rates and retardation factors were found for all tested flow velocities.often overlooked, which corresponds to ignoring the effect of different flow velocities on the fate of contaminants. Reducing the complexity at field sites, laboratory experiments in column studies can help to identify the specific sorption and biodegradation rates of pharmaceuticals.Column experiments are frequently used to study the transport of contaminants like micropollutants, such as pharmaceuticals [7]. Numerous studies have proven the usefulness of column experiments, as they are relatively fast, uncomplicated to manage, and their boundary conditions can be easily controlled. Moreover, different scenarios may be simulated, for example, managed aquifer recharge [8], seepage through the vadose zone [9], transport through an aquifer [10,11], and bank filtration [12][13][14].Column studies have been utilized to study the influence of physico-chemical conditions within an aquifer on pharmaceutical transport, with an emphasis on changes in pH [11], redox conditions [13,15], or temperature [16]. Also, the influence of the sediment type on transport behavior was studied and the following properties were found particularly crucial: Sediment grain size [17], available mineral surfaces [18], or total organic carbon content [19]. However, little is known on the impact of flow velocity on pharmaceutical transport in groundwater [20].The effect of pore-water velocity on contaminant transport has been presented in the literatur...

Pollutant Dissipation at the Sediment‐Water Interface: A Robust Discrete Continuum Numerical Model and Recirculating Laboratory Experiments

“…The modeled and simulated mass fluxes fitted well after adjustment with a K d value of 3.0 mL·g −1 , rather than using the experimental (Figure 4a), ( and ) (Figures 4b and 4c). This observation is consistent with a previous study reporting a sorption coefficient twice lower for the pharmaceutical atenolol in column experiments than in batch sorption experiments (Kiecak et al., 2019). Although in‐bed measurements were not possible for experiments with FB291, similar observed and simulated patterns of FB291 penetration into the sediment bed confirmed the validity of simulations in the case of IHF FB291 (Figure 6a and 6b).…”

Improved Short-Term Microbial Degradation in Circulating Water Reducing High Stagnant Atrazine Concentrations in Subsurface Sediments

“…In long-term (180 days) degradation experiments, using low atrazine concentrations of 20 µg L −1 in water circulating columns at a flow rate of 2 mL min −1 , atrazine dissipation rates have been estimated to be two to five times faster than in stagnant flasks [5], while pharmaceuticals dissipation was not enhanced at flow rates of 1.7-3.4 mL min −1 [65]. The short-term results of this study showed that at quite a high atrazine concentration below 10-18 mg L −1 , high flow rate (16.7 mL min −1 )-induced changes in the sediment columns did not improve atrazine dissipation, apparently due to the good colloid formation ability [21][22][23], while the amount adsorbed to the sediments was low (about 50.1 µg).…”

Amended Vegetation Filters as Nature-Based Solutions for the Treatment of Pharmaceuticals: Infiltration Experiments Coupled to Reactive Transport Modelling

“…Column experiments coupled with numerical modelling are useful tools to rapidly test soil amendments prior to its incorporation in real VFs and to delineate the dynamics of water flow and contaminant transport within porous media providing predictive insights into the fate and migration of contaminants. The predominant focus in pharmaceuticals of recent research has leaned towards experiments conducted under saturated conditions particularly to forecast their transport in aquifers and natural soils, as well as during processes such as aquifer recharge, agriculture and urban irrigation and soil aquifer treatment [41][42][43][44][45][46][47]. In contrast, investigations carried out under unsaturated conditions are comparatively limited, and even scarcer are studies conducted under unsaturated conditions that employ soil amendments as a treatment approach for pharmaceutical removal.…”