Microplastics, MPs, plastic particles with dimensions between 0.1 and 5 mm, represent an important environmental pollutant. The removal of microplastics from natural and wastewater is a challenging research topic. In this regard, high-performance technical solutions must be identified, which can be based on existing treatment and purification technologies, to ensure their removal at concentration values in accordance with the legislation in force. In this study, the efficiency of removing some fractions of polyurethane microplastics, with dimensions smaller than 500 µm, from aqueous synthetic solutions with a concentration of 0.2 g L⁻¹, i.e., around 175 NTU, was evaluated. In the first stage of the study, the doses of coagulants and flocculants effective for the removal of microplastics were identified through the Jar Test. The variation in turbidity and their removal efficiencies were evaluated in the presence of classic coagulants, such as aluminum sulfate, Al₂(SO₄)₃·18H₂O, SA; iron sulfate (ferrous sulfate), FeSO₄, IS; polyaluminum chloride, [Al₂(OH)_nCl_6−n], PAC; Aloe Vera, AV, a flocculant; and activated carbon, AC, of the Norit GAC 830 W type. Classic coagulants, such as aluminum sulfate, have a good efficiency in removing microplastics, being able to provide a residual turbidity in the range of 6–10 NTU after a retention time of 50–60 min. In the second stage of the study, the removal efficiency of microplastics was tested using a laboratory pilot plant—called in the study the Smart Decantation-Filtration System, SDFS. The efficiency of the decanter was studied using Response Surface Methodology (RSM) to identify mathematical models that characterize the influence of key process variables: flow rate (A), microplastic size (B) and aluminum sulfate concentration (C) on microplastic removal efficiency. Sedimentation in the specially constructed decanter can raise the optimal value of the removal efficiency of polyurethane microplastics to 98.98%, and filtration can ensure an efficiency that reaches over 99.5%. Through this research, we aimed to identify viable solutions that can be applied to remove microplastics, MPs, from natural and wastewater. A novel element is the fact that we chose to study the removal of polyurethane, which is studied little in the literature. We identified the optimal doses of coagulants and flocculants that help sedimentation of MPs. The efficiency of an installation called Smart Decantation-Filtration System, specially designed to ensure increased efficiency in the removal of microplastics, was determined. The results obtained were encouraging.

Microplastics, plastic particles smaller than 5 mm in size, have become a contaminant of priority concern in the environment. Microplastic pollution is a significant environmental challenge, highlighting the need for improved water treatment methods. This study investigates the removal of two fractions of polyurethane microplastics ranging in size from smaller than 100 µm, D1, and in range 200 µm - 500 µm, D2, from aqueous synthetic solutions having a concentration of 0.2 g/L, around 175 NTU. In the first stage of the study, tests were performed to identify the optimal doses of efficient reactive agents for microplastic removal, using the classical method: the Jar test. At this stage, attention was directed towards analyzing the variation of turbidity and their removal efficiency in the presence of classical coagulants such as aluminum sulfate, SA, ferrous sulfate, SF, aluminum polychloride, PA; aloe vera flocculant; and activated carbon, CA of the Norit GAC 830 W type. The classical coagulants such as aluminum sulphate, ferrous sulphate have a good efficiency on microplastic removal, which can provide a residual turbidity in range of 6-10 NTU after a retention time of 50 - 60 minutes. In the second stage of the study, the efficiency of smart decantation-filtration system, DFS, was determined. The efficiency of decanter was studied using Response Surface Methodology (RSM) for identification of the mathematical models necessary to evaluate the effects of key process variables: Flow rate (A), Microplastic size (B), and Aluminum sulphate concentration (C) on microplastic removal efficiency. The sedimentation can raise the optimal value of 98.98 % at the outlet of the decanter. Microplastics in D1 and D2 sized synthetic solutions can be removed from contaminated water by decantation and filtration, the efficiency is around maximum permissible limit, MPL, values of 1 NTU.

The paper presents an automated, remotely controlled installation for the continuous-flow disinfection of treated wastewater. The proposed solution ensures the inactivation of microorganisms without heating the fluid and without the use of chemical disinfectants, thus reducing the environmental impact and resource consumption associated with conventional disinfection methods. The destruction of microorganisms is achieved by applying high-intensity electrical pulses, which cause irreversible permeabilization of cell membranes through the phenomenon of electroporation. The installation is fully automated and based on a closed-loop control system, in which a programmable logic controller (PLC) acquires data from specialized sensors and automatically regulates the process variables according to the measured operating conditions. The system implements a closed-loop control strategy, optimizing the amplitude, duration and frequency of the electrical pulses depending on the characteristics of the treated fluid and the working flow rate. By eliminating chemical reagents and limiting thermal effects, the proposed technology contributes to reducing energy consumption and increasing the sustainability of the disinfection process. The integration of electroporation with modern automation and monitoring solutions supports the implementation of circular economy principles and the development of sustainable strategies for the management and reuse of treated wastewater. The proposed PLC-SCADA architecture enables adaptive real-time control of the disinfection process by continuously adjusting pulse amplitude, duration, and repetition frequency according to wastewater characteristics and flow conditions. Compared with conventional chemical disinfection methods, the system eliminates the need for chemical reagents and minimizes the formation of secondary pollutants. In addition, the continuous-flow configuration facilitates integration into existing wastewater treatment infrastructures while supporting sustainable and energy-efficient operation.

Drinking water is essential for humans; its quality determines the health and proper functioning of the body. In order to obtain drinking water in accordance with the legislation in force, the performance of the technology applied for water treatment and the infrastructure for transport and distribution to the consumer are equally important. Particular importance to this last aspect was given by the introduction of European Directive 2020/2184. Infrastructure can significantly influence water quality due to the fact that there are periods when water stagnates in the pipe and electro-corrosion processes, and salt deposits or degradation/corrosion of the pipes can occur, or periods when water circulates under pressure, when deposits but also particles from the pipes are mechanically detached and transported to the consumer. In this article, we aim to present the behavior of asbestos-cement pipes, AC, special steel for pipes OLT 37, galvanized steel, OLT 37.1, and high-density polyethylene, HDPE, in contact with drinking water. The study was conducted in Calarasi city, Calarasi county, Romania, where some of the old pipes were replaced. A comparative study of new pipes of the same type with pipes in use for more than 20 years, up to 46 years, was conducted, and at the same time the changes that the pipes (which have not yet been replaced) have on the quality of drinking water for street consumers were also analyzed. Following the analyses performed, it can be stated that the water quality is within the maximum permissible limits, but the micropollutants that appear can accumulate in the body (such as AC microfibers, microplastics, metallic zinc, zinc ions, iron ions, manganese, aluminum) with effects that can be evident after a long period of consumption through bioaccumulation.