Pesticides are used worldwide in agriculture to prevent insects and other pests that attack plants and their derivatives. Acetamiprid (ACT) is a type of insecticide belonging to the chemical group of neonicotinoids, which are widely used in agricultural planting to replace organophosphates. Therefore, in this work, the performance of the electrochemical oxidation (EO) process as an alternative solution to eliminate pesticides in water was evaluated. A dimensionally stable anode (DSA, TiO₂-RuO₂-IrO₂) and boron-doped diamond (BDD) were tested as anodes for degrading ACT (30 and 300 mg L⁻¹) by using different applied current densities (j): 30, 60, 90, and 120 mA cm⁻². The degradation process was monitored by using ACT decay, spectrophotometric analysis, and chemical oxygen demand. The results clearly showed that ACT (30 mg L⁻¹) was only eliminated from water at the DSA electrode when 90 mA cm⁻² was applied, reaching higher removal efficiencies after 180 min of electrolysis. Conversely, ACT was quickly removed at all applied current densities used, at the same concentration. On the other hand, when the ACT concentration was increased (300 mg L⁻¹), 71.4% of the COD removal was reached by applying 90 mA cm⁻² using BDD, while no significant improvements were achieved at the DSA electrode when a higher concentration of ACT was electrochemically treated.

The occurrence of contaminants of emerging concern (CECs) in several environmental compartments has raised significant concern given the extensive array of compounds and their consistent detection across various environmental matrices. Monitoring all potentially harmful compounds and identifying their sources is nearly impossible. However, providing data on their occurrence is crucial and lays the groundwork for decision makers to craft mitigation strategies toward a more sustainable water policy. Hence, the primary aim of this study was to conduct an evaluation study on CECs occurrence in the environment. The main novelty relies on understanding their specific pathway in three different environmental aquatic compartments. For that, a combined study of a systematic review and systemic analysis was performed. Initially, the five most common types of CECs found in aquatic ecosystems (groundwater and surface water) and wastewater were considered. For each group of CECs, five contaminants were identified. A bibliographic portfolio was generated through the application of a systematic review. Finally, a systemic analysis of the bibliographic portfolio was conducted. All classes of contaminants studied were identified in the environmental compartments evaluated. Except for pesticides, the degree of contamination by CECs followed a sequence based on the aquatic compartment (i.e., WW–SW–GW).

Oil leakage occurs at fuel service stations due to improper storage, which pollutes soil and, subsequently, can reach the groundwater. Many compounds of petroleum-derived fuels pose hazards to aquatic systems, and so must be treated to guarantee clean and safe consumption, which is a right proposed by the United Nations in their Sustainable Development Goal 6 (SDG 6: Clean Water and Sanitation). In this study, contaminated groundwater with emerging pollutants by petroleum-derived fuel was electrochemically treated in constantly mixed 0.5 L samples using three different anodes: Ni/BDD, Ti/Pt, Ti/RuO₂. Parameters were investigated according to chemical oxygen demand (COD), energy consumption analysis, by applying different electrodes, current densities (j), time, and the use of Na₂SO₄ as an electrolyte. Despite a similar COD decrease, better degradation was achieved after 240 min of electrochemical treatment at Ti/RuO₂ system (almost 70%) by applying 30 mA cm⁻², even without electrolyte. Furthermore, energy consumption was lower with the RuO₂ anode, and greater when 0.5 M of Na₂SO₄ was added; while the order, when compared with the other electrocatalytic materials, was Ti/RuO₂ > Ti/Pt > Ni/BDD. Thereafter, aiming to verify the viability of treatment at a large scale, a pilot flow plant with a capacity of 5 L was used, with a double-sided Ti/RuO₂ as the anode, and two stainless steel cathodes. The optimal conditions for the effective treatment of the polluted water were a j of 30 mA cm⁻², and 0.5 M of Na₂SO₄, resulting in 68% degradation after 300 min, with almost complete removal of BTEX compounds (benzene, toluene, ethyl-benzene, and xylene, which are found in emerging pollutants) from the water and other toxic compounds. These significant results proved that the technology used here could be an effective SDG 6 electrochemical-based solution for the treatment of groundwater, seeking to improve the quality of water, removing contaminants, and focusing on Brazilian environmental legislations and, consequently, converting pollutants into effluent that can be returned to the water cycle.