Combined process for removal of tetracycline antibiotic – Coupling pre-treatment with a nickel-modified graphite felt electrode and a biological treatment

Abstract

a b s t r a c tBiodegradability improvement of tetracycline-containing solutions after an electrochemical pretreatment was examined. Cyclic voltammetry with a nickel electrode revealed a significant electrochemical activity of tetracycline, in both oxidation and reduction. Electrochemical treatment was therefore performed in a home-made flow cell using a nickel-modified graphite felt electrode as the working electrode. Optimal conditions, namely 100 mg l À1 initial tetracycline, above 0.45 V potential, and between 1 and 6 ml min À1 flow rate, led to a more than 99% conversion yield of tetracycline in oxidation in alkaline conditions, after only a single pass through the percolation cell. However, total organic carbon (TOC) analyses revealed a low mineralization level, i.e., always below 31%, underscoring the importance of a combined electrochemical and biological treatment. This was confirmed by the favorable trends of the COD/TOC ratio, decreasing from 2.7 to 1.9, and the average oxidation state, increasing from 0.044 to 1.15, before and after oxidation pretreatment at 0.7 V and 3 ml min À1 flow rate. Electrolyzed solutions appeared biodegradable, since BOD 5 /COD increased from 0 to 0.46 for untreated and pretreated TC at 0.7 V/SCE. Biological treatment showed only biosorption for non-pretreated tetracycline, while after 11.5 days of culture, the mineralization of solutions electrolyzed in oxidation was 54%, leading to a 69% overall TOC decrease during the combined process.

Preparation of Silver‐Modified Nickel Foams by Galvanic Displacement and Their Use as Cathodes for the Reductive Dechlorination of Herbicides

“…Chloroacetanilides are a commonly used class of herbicides that may pollute surface waters. An elegant strategy for the removal of such biorecalcitrant compounds from the environment is based on two steps: 1) a physicochemical pre‐treatment, for example, an electrochemical oxidation/reduction used to obtain less toxic and more biodegradable intermediates; and 2) a subsequent biological treatment to achieve the complete mineralisation of the substrate . For chlorinated pollutants, such as chloroacetanilides, the pre‐treatment consists of breaking the Cl−C bond through electrochemical reduction, leading to one or more Cl‐free compounds that may be oxidised exhaustively to CO 2 by bacteria during the second step.…”

Electrocatalytic reduction of metronidazole using titanocene/Nafion®-modified graphite felt electrode

“…In recent years, the combined processes, in particular physicochemical and biological combined treatments, have received a growing attention for their efficiency to achieve complete mineralization of biorecalcitrant compounds with the objective to reduce operating costs [1][2][3][4][5][6][7][8][9][10][11][12]. In such systems, a physicochemical pretreatment such as an advanced oxidation process (AOP) or an electrochemical method is used to change the structure of pollutants.…”

“…The aim is to obtain less toxic and more biodegradable intermediates, giving rise to a complete mineralization after a subsequent biological treatment. A lot of studies have highlighted the possibility to use combined processes for the removal of non-biodegradable pollutants such as pesticides [1, 4-6, 9, 11, 13-15], dyes [7,10] and pharmaceuticals [3,8,12,[16][17][18][19].…”

“…For example, the coupling of a pretreatment with a nickel -modified graphite felt electrode and a biological treatment for the removal of a biorecalcitrant antibiotic, tetracycline, has been carried out [12]. Tetracycline can be oxidized in alkaline conditions on nickel at an oxidation potential of 0.5 V/SCE, which is significantly lower than with a graphite felt electrode (1 V/SCE).…”

Efficient adsorption removal of tetracycline by layered carbon particles prepared from seaweed biomass

“…Although the environmental concentrations of tetracyclines are very low, the chronic exposure may still exert pressure on the evolution of antibiotic resistant bacteria which in turn may minimize the effectiveness and therapeutic value of antibiotics . As the molecules of tetracyclines are usually neutral or negatively charged in environmental water, the conventional techniques for tetracycline removal such as sedimentation, sand filtration, flocculation, and coagulation are not so efficient as expected . Furthermore, a number of oxidation processes such as photodegradation , ozonation , photo‐Fenton process , photoelectrocatalytic degradation were utilized for the effective removal of tetracycline.…”