Coupling of Nanofiltration and Thermal Fenton Reaction for the Abatement of Carbamazepine in Wastewater

Abstract

The complete removal of biorecalcitrant xenobiotics, including most notably the pharmaceutical pollutants, by advanced oxidation processes is often difficult to be reached in urban or industrial wastewater because of the high concentration of organic and inorganic scavengers that compete with the xenobiotics for the oxidizing species. This work investigates a coupled treatment train in which wastewater effluents are pretreated with a negatively charged loose nanofiltration (NF) membrane (HydraCoRe70, made up of sulfonated polyethersulfone) to enhance the removal of xenobiotics with the thermal Fenton process. Carbamazepine (CBZ), a drug prescribed mainly for epilepsy treatment, is used here as a model xenobiotic. After optimizing the conditions for separation and degradation, the NF–Fenton approach was applied to both synthetic wastewater and real samples to assess the overall efficiency of CBZ removal. The Fenton degradation of CBZ was drastically enhanced in nanofiltered samples, thanks to the removal by the membrane of nearly all organic matter that would otherwise consume the reactive oxidizing species (e.g., the hydroxyl radical). On the basis of a preliminary treatment cost analysis, it can be concluded that the combined process is potentially applicable to the treatment of several kinds of wastewaters (e.g., industrial ones) to favor the removal of biorecalcitrant contaminants. Key cost savings of NF–Fenton concern the lower amounts of Fenton reagents needed to degrade CBZ and (even more importantly) the decreased levels of acids and bases for pH adjustment before and after the oxidative process because of the lower buffer capacity of the NF permeate compared to feed wastewater, after the removal by the NF of many inorganic ions and most organic carbon.

Metabisulfite as an Unconventional Reagent for Green Oxidation of Emerging Contaminants Using an Iron-Based Catalyst

“…This finding is similar to recent results, obtained in the framework of the traditional Fenton reaction. 32 Duplicates and triplicates of these tests are presented in Figure S1 of the Supporting Information. The replicate tests showed high robustness, implying the reproducibility of the adopted experimental procedures.…”

“…In fact, within the same time interval, more reagent (higher concentration of metabisulfite) is available to react with the reactive species present in the system, compared with the addition of the same overall amount of the reagent in separate steps. 32 Based on these results, the multiple addition approach appears to be the most rational way to use the S 2 O 5 2– reagent, and it was chosen hereafter to perform the degradation of the contaminants under study.…”

A novel modeling approach for a generalizable photo-Fenton-based degradation of organic compounds

“…Under these conditions, retention time was 9.0 min. Samples were taken at 0.0, 1.5, 2.5, 5.0, 7.5, 10.0, and 15.0 min and were previously treated with methanol (in proportion 50:50) in order to stop further degradation of PCT, being a well-known HO • scavenger (Tadolini and Cabrini 1988;Múčka et al 2013;Minella et al 2018).…”

Degradation of ibuprofen and phenol with a Fenton-like process triggered by zero-valent iron (ZVI-Fenton)

“…The adjustment of [Fe 2+ ] and [H 2 O 2 ] is also aimed at minimizing • OH scavenging by both species (Neyens and Baeyens 2003). However, this approach suffers from at least two important drawbacks: (i) the cost of the pH-fixing reagents is at least as high as that of H 2 O 2 , and together they make up ∼80% of the expense for chemicals in the Fenton process (Minella et al 2018);(ii) when treating actual wastewater, the recycling of Fe(III) via reactions (2,3) is too slow to be effectively exploited in a real-world scenario (Minella et al 2018). An alternative way to tackle the problem is represented by heterogeneous Fenton, where the Fe source is a solid material (better if magnetic, which makes subsequent separation easier) (Pastrana-Martínez et al 2015;…”

“…In addition, the use of ZVI as iron source to promote the Fenton oxidation has been scarcely investigated in real wastewaters. In this matrix, the degradation efficiency may be lower than in laboratory systems due to the interference by organic matter and inorganic ions (Minella et al 2018). Finally, to our knowledge the economics of the process in real wastewater has been scarcely taken into account, which is a problem because economic considerations are of paramount importance in water treatment.…”