Evaluation of Fenton and modified Fenton oxidation coupled with membrane distillation for produced water treatment: Benefits, challenges, and effluent toxicity

Membrane distillation is a promising technology to desalinate hypersaline produced waters. However, the organic content can foul and wet the membrane, while some fractions may pass into the distillate and impair itsquality. In this study, the applicability of the traditional Fenton process was investigated and preliminarily optimized as a pre-treatment of a synthetic hypersaline produced water for the following step of membrane distillation. The Fenton process was also compared to a modified Fenton system, whereby safe iron ligands,i.e., ethylenediamine-N,N′-disuccinate and citrate, were used to overcome practical limitations of the traditionalreaction. The oxidation pre-treatments achieved up to 55% removal of the dissolved organic carbon and almostcomplete degradation of the low molecular weight toxic organic contaminants. The pre-treatment steps didnot improve the productivity of the membrane distillation process, but they allowed for obtaining a final effluentwith significantly higher quality in terms of organic content and reduced Vibrio fischeri inhibition, with halfmaximal effective concentration (EC50) values up to 25 times those measured for the raw produced water. Theaddition of iron ligands during the oxidation step simplified the process, but resulted in an effluent of slightlylower quality in terms of toxicity compared to the use of traditional Fenton.

Investigation on the Efficiency of Modified Fenton on the Treatment of Leachate Generated From Oily Sludge Composting

Background: and Aim The leachate from oil sludge compost into the environment, which is resistant to decomposition, causes several environmental problems. Therefore, it needs to be treated using efficient processes. This study aimed to investigate the efficiency of the modified Fenton process for treating these oil sludge leachates. Methods & Materials: In this experimental study, leachate samples were collected, and then modified Fenton solution was prepared by adding Fe2 (SO4) 3 to H2O2. Then the effect of time parameters (15, 30, 60, 90, and 120 minutes), modified Fenton concentration of 20, 50, 100, and 200 mg/l with pH 3, 5, 9, and three initial concentration of COD (500, 1000 and 1500 mg/l) was examined. Ethical Considerations: This study has been registered in Arak University of Medical Sciences with codes 2645 and 2765. Results: The reduction of COD and TPH in the optimal time of 60 minutes, initial COD of 500 mg/l, pH of 3, and Fenton concentration of 200 mg/l were 9.04 and 77.42%, respectively. The experiments showed that the removal efficiency of COD and TPH with increasing residence time and the concentration of modified Fenton are directly proportional and with decreasing, the initial concentration of COD and pH is inversely proportional. Conclusion: The use of modified Fenton is an efficient method for treating leachate from petroleum sludge compo

The Use of an Ultrasonic Field in Support of Classical Methods of Oxidising Component Leached from Microplastics in Bottom Sediments

The work detailed here examined the impact of selected unit methods and ultrasonic removal of the widespread plastic additive di(2-ethylhexyl) phthalate (DEHP) from the bottom sediments of a body of water. To this end, hydrogen peroxide and a classic or modified Fenton process were used, supplemented by an ultrasonic field. The latter had a vibration frequency of 20 kHz and an acoustic wave intensity of 3.97 W/cm2. The impact of process parameters such as reaction environment, reaction time, initial impurity content, aging of the impurity, influence of processes on the content of organic matter and dissolved organic carbon, and elution of selected components from the matrix were all analysed. It emerged that the most effective process by which to remove DEHP from a solid matrix involved a modified Fenton process assisted by an ultrasonic field. The highest average degradation efficiency achieved in this way was 70.74%, for C0 = 10 mg/kg d.w. and t = 60 min.

Effectiveness of chelating agent-assisted Fenton-like processes on remediation of glucocorticoid contaminated soil using chemical and biological assessment: performance comparison of CaO2 and H2O2

Glucocorticoids (GCs) have drawn great concern due to widespread contamination in the environment and application in treating COVID-19. Most studies on GC removal mainly focused on aquatic environment, while GC behaviors in soil were less mentioned. In this study, degradation of three selected GCs in soil have been investigated using citric acid (CA)-modified Fenton-like processes (H2O2/Fe(III)/CA and CaO2/Fe(III)/CA treatments). The results showed that GCs in soil can be removed by modified Fenton-like processes (removal efficiency > 70% for 24 h). CaO2/Fe(III)/CA was more efficient than H2O2/Fe(III)/CA at low oxidant dosage (< 0.28–0.69 mmol/g) for long treatment time (> 4 h). Besides the chemical assessment with GC removal, effects of Fenton-like processes were also evaluated by biological assessments with bacteria and plants. CaO2/Fe(III)/CA was less harmful to the richness and diversity of microorganisms in soil compared to H2O2/Fe(III)/CA. Weaker phytotoxic effects were observed on GC-contaminated soil treated by CaO2/Fe(III)/CA than H2O2/Fe(III)/CA. This study therefore, recommends CaO2 based treatments to remediate GC-contaminated soils.