Mechanism of interactions in C.I. Acid Red 18 – Floating plants and polymeric resins systems: Kinetic, equilibrium, auxiliaries impact and column studies

Removal of contaminants of emerging concern by Wolffia arrhiza and Lemna minor depending on the process conditions, pollutants concentration, and matrix type

Research was carried out on the removal of a group of six contaminants of emerging concern: bisphenol A, N,N-diethyl-m-toluamide, diethylstilbestrol, triclosan, estrone and estradiol from the water matrix during contact with small floating macrophytes Wolffia arrhiza and Lemna minor. The optimal conditions for the process, such as pH, light exposure per day, and plant mass, were determined using the design of experiments chemometric approach based on central composite design. Experiments conducted under the designated optimal conditions showed that after 7 days, the removal efficiency equals 88-98% in the case of W. arrhiza and 87-97% in the case of L. minor, while after 14 days of the experiment, these values are 93-99.6% and 89-98%, respectively. The primary mechanism responsible for removing CECs is the plant uptake, with the mean uptake rate constant equal to 0.299 day-1 and 0.277 day-1 for W. arrhiza and L. minor, respectively. Experiments conducted using municipal wastewater as a sample matrix showed that the treatment efficiency remains high (the average values 84% and 75%; in the case of raw wastewater, 93% and 89%, and in the case of treated wastewater, for W. arrhiza and L. minor, respectively). Landfill leachate significantly reduces plants' ability to remove pollutants (the average removal efficiency equals 59% and 56%, for W. arrhiza and L. minor, respectively).

Anaerobic Reactor Filling for Phosphorus Removal by Metal Dissolution Method

A commonly indicated drawback of anaerobic wastewater treatment is the low effectiveness of phosphorus removal. One possibility to eliminate this disadvantage is the implementation of active fillings that contain admixtures of metals, minerals, or other elements contributing to wastewater treatment intensification. The aim of the research was to present an active filling produced via microcellular extrusion technology, and to determine its properties and performance in anaerobic wastewater treatment. The influence of copper and iron admixtures on the properties of the obtained porous extrudate in terms of its functional properties was also examined. The Barus effect increased with the highest content of the blowing agent in the material from 110 ± 12 to 134 ± 14. The addition of metal powders caused an increase in the extrudate density. The modification of PVC resulted in the highest porosity, amounting to 47.0% ± 3.2%, and caused the tensile strength to decrease by about 50%. The determined values ranged from 211.8 ± 18.3 MPa to 97.1 ± 10.0 MPa. The use of the filling in anaerobic rectors promoted COD removal, intensified biogas production, and eliminated phosphorus with an efficiency of 64.4% to 90.7%, depending on the type of wastewater and applied technological parameters.

Purification of Textile Effluents Containing C.I. Acid Violet 1: Adsorptive Removal versus Hydrogen Peroxide and Peracetic Acid Based Advanced Oxidation

Textile effluent containing azo dyes such as C.I. Acid Violet 1 (AV1) can be degraded to toxic aromatic amines in the environment. Thus, there is a legitimate need to treat such effluents before they are discharged to surface waters. Two methods were proposed to remove AV1 from aqueous solutions: adsorption and advanced oxidation processes (AOPs). The sorption capacity of the strongly basic anion exchanger Purolite A520E of the polystyrene matrix determined from the Langmuir isotherm model was found to be 835 mg/g, while that of Lewatit S5428 of the polyacrylamide matrix Freundlich model seems to be more appropriate for describing the experimental data. The pseudo-second-order kinetic model and external diffusion are the rate limiting steps of adsorption. The removal efficiency of AV1 by the anion exchangers was higher than 99% after 40 min of phase contact time. AOPs involved the usage of hydrogen peroxide and peracetic acid (PAA) as oxidizing agents, while Fe2+ and simulated sunlight were used as oxidizing activators. AV1 oxidation followed the pseudo-first-order kinetics, and the systems with the highest values of the rate constants turned out to be those in which Fe2+ was present. The efficiency of oxidation measured by the degree of decolorization in the systems with Fe2+ was higher than 99% after 10–60 min. AV1 mineralization was slower, but after 120 min of oxidation it was higher than 98% in the H2O2/Fe2+, PAA/Fe2+ and PAA/Fe2+/sunlight systems.