Emerging investigator series: Electrochemically-mediated Remediation of GenX Using Redox-Copolymers

Per- and polyfluorinated alkyl substances (PFAS) are persistent contaminants that have been continuously detected in groundwater and drinking water around the globe. Hexafluoropropylene oxide dimer acid (tradename GenX) has been...

INCREASING THE PERFORMANCE OF CYLINDRICAL SEPARATORS FOR CEREAL CLEANING, BY USING AN INNER HELICAL COIL

Rotary seed sorters used for wheat processing show some functional advantages in eliminating persistent contaminants, especially due to the more aggressive treatment applied to the processed material. The objective of this paper was to design a new constructive subassembly that would increase the performance of rotary sorters used for extracting various contaminants from seeds. By testing a pilot stand that reproduces the operation of a professional equipment and developing mathematical models that fits the main operating parameters, it was possible to identify the new characteristics needed to improve cylindrical sieves and to optimize the functioning of this equipment.

Treatment of textile dyes using advanced oxidative and adsorptive processes individually and combined: study of the operational parameters, kinetic and adsorptive equilibrium

Advanced oxidative processes (AOP) have been consolidated as an efficient treatment technique to degrade persistent contaminants. In addition to them, biosorption also emerges as a technique capable of removing both pollutants and intermediate products generated by other treatments such as AOP. Thus, this work evaluated the degradation and removal of the mixture of dyes Direct Red 23 and Direct Red 227 in aqueous solution (50 mg·L−1 of each). Preliminary tests showed that the photo-Fenton system under sunlight radiation was the most efficient, reaching a degradation ≥93%. For the adsorptive process using chicken eggshell, preliminary tests indicated that the ideal dosage of adsorbent was 8.0 g·L−1. For this process, a factorial design indicated the best working conditions, which demonstrated from the system adjusted well to the Elovich (kinetic) model and to the Freundlich and Sips models (equilibrium). When associating the two processes, AOP followed by adsorption achieved a total degradation/removal of ≈98% (for all λ) in a time of 60 min. Thus, the feasibility of the combined treatment is indicated.

Combating paraben pollution in surface waters with a variety of photocatalyzed systems: Looking for the most efficient technology

The constant presence of parabens in natural surface waters has raised a growing concern of the potential long-term toxic effects that parabens may have in wildlife, mainly as endocrine disruptors. The present report describes the results of a study in which different photocatalyzed systems, such as photo-Fenton, Fenton, UV-H2O2, UV-TiO2 and UV-TiO2-H2O2, were applied to the removal of these recalcitrant pollutants in some surface waters, including natural (e.g. rivers) and man-made (e.g. reservoirs and wastewater treatment plants). Degradation of four widely-used parabens (methyl-paraben, ethyl-paraben, propyl-paraben and butyl-paraben) was analyzed. Experimental results reveal that the most efficient method to combat these emerging pollutants was photo-Fenton. When this process was optimized, optimal removal efficiency was attained using doses of H2O2 and Fe(II) equal to 2.92·10−4 mol dm-3 and 1.85·10−5 mol dm-3, respectively. It is also worth noting that the removal rate of these contaminants is slower in natural waters. The results suggest that the photo-Fenton process is promising and maybe an adequate technology for the treatment of these persistent contaminants.

Health Risk Modifiers of Exposure to Persistent Pollutants among Indigenous Peoples of Chukotka

The aim of the study was to assess temporal trends in health risks related to most common persistent contaminants, including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethanes (DDTs), lead (Pb), as well as mercury (Hg) among indigenous peoples living in coastal areas of Chukotka in Arctic Russia. This is examined in relation to exposure pathways and a range of social and behavioral factors capable of modifying the exposure to these contaminants, including place of residence, income, traditional subsistence, alcohol consumption, and awareness of risk prevention. The primary exposure pathway for PCBs is shown to be the intake of traditional foods, which explained as much as 90% of the total health risk calculated employing established risk guidelines. Nearly 50% of past DDT-related health risks also appear to have been contributed by contaminated indoor surfaces involving commonly used DDT-containing insecticides. Individuals who practiced traditional activities are shown to have experienced a 4.4-fold higher risk of exposure to PCBs and a 1.3-fold higher risk for DDTs, Pb, and Hg. Low income, high consumption of marine mammal fat, alcohol consumption, and lack of awareness of health risk prevention are attributed to a further 2- to 6-fold increase in the risk of PCBs exposure. Low socioeconomic status enhances the health risks associated with exposure to the persistent contaminants examined.