Sorption of sulfadiazine and flow modeling in an alluvial deposit of a dry riverbed in the Brazilian semiarid

Biodegradation, photolysis, and sorption of antibiotics in aquatic environments: A scoping review

The presence of antibiotics in surface waters is a potential driver of antibiotic resistance and thus of concern to human and environmental health. Key factors driving the potential impact of antibiotics are their persistence and transport in rivers and lakes. The goal of this study was to describe the peer-reviewed published literature on the photolysis (direct and indirect), sorption, and biodegradation of a selected group of antibiotic compounds following a scoping review methodology. Primary research from 2000 to 2021 was surveyed to compile information on these processes for 25 antibiotics from 6 classes. After compilation and assessment of the available parameters, the results indicate that information is present to predict the rates of direct photolysis and reaction with hydroxyl radical (an indirect photolysis process) for most of the selected antibiotics. There is insufficient or inconsistent information for including other indirect photolysis processes, biodegradation, or removal via sorption to settling particles for most of the targeted antibiotic compounds. Future research should focus on collecting fundamental parameters such as quantum yields, second-order rate constants, normalized biodegradation rates, and organic carbon or surface area normalized sorption coefficients rather than pseudo-first order rate constants or sorption equilibrium constants that apply only to specific conditions/sites.

Transport Behavior of RB5 Dye in Alluvial Soil in the Northeast of Brazil

The textile industry generates a large volume of chemically diversified effluents containing, among other compounds, dyes. Untreated wastes are contaminants to surface water, soil, and groundwater. In this aspect, various studies have explored the issue of contamination of alluvial soils in the Alto Capibaribe region, northeast of Brazil, due to local textile activity. This region, inserted into the Brazilian semiarid region, suffers from water scarcity, and there is a need for rural communities to use alluvial formations for water supply. The simulation of solute transport is a fundamental tool for understanding the environmental performance and risks associated with contamination by textile dyes. Transport parameters that directly influence pollutant dynamics in sedimentary environments are characterized. This study evaluated the retention and mobility of the dye Remazol Black 5 (RB5) in two superficial layers of alluvial soil from Alto Capibaribe to obtain transport parameters. In the laboratory, tests of mobility in soil columns with RB5 dye (concentration of the 25 mg L−1) and KBr tracer (concentration of the 35.7 g L−1) solutions were conducted. The CDE and two-region models were used to model the KBr experimental transport data, and the two-site model was used to model the RB5 experimental transport data. Physical non-equilibrium was found in the soils for KBr transport, and the two-region model adequately modeled the experimental breakthrough curves (BTCs). For the transport of RB5, the results showed a chemical non-equilibrium, and the two-site model was adequate to model the experimental BTCs. The results indicate that the surface layer is most responsible for the retention of RB5, where the RB5 solution was less mobile than in the lower layer. Both layers showed low retention and high mobility for RB5, indicating that the RB5 dye in the region may contaminate groundwater.