Biogenic Palladium Enhances Diatrizoate Removal from Hospital Wastewater in a Microbial Electrolysis Cell

Abstract

To decrease the load of pharmaceuticals to the environment, decentralized wastewater treatment has been proposed for important pointsources such as hospitals. In this study, a microbial electrolysis cell (MEC) was used for the dehalogenation of the iodinated X-ray contrast medium diatrizoate. The presence of biogenic palladium nanoparticles (bio-Pd) in the cathode significantly enhanced diatrizoate removal by direct electrochemical reduction and by reductive catalysis using the H 2 gas produced at the cathode of the MEC. Complete deiodination of 3.3 μM (2 mg L À1 ) diatrizoate from a synthetic medium was achieved after 24 h of recirculation at an applied voltage of À0.4 V. An equimolar amount of the deiodinated metabolite 3,5-diacetamidobenzoate (DAB) was detected. Higher cell voltages increased the dehalogenation rates, resulting in a complete removal after 2 h at À0.8 V. At this cell voltage, the MEC was also able to remove 85% of diatrizoate from hospital effluent containing 0.5 μM (292 μg L À1 ), after 24 h of recirculation. Complete removal was obtained when the effluent was continuously fed at a volumetric loading rate of 204 mg diatrizoate m À3 total cathodic compartment (TCC) day À1 to the MEC with a hydraulic retention time of 8 h. At À0.8 V, the MEC system could also eliminate 54% of diatrizoate from spiked urine during a 24 h recirculation experiment. The final product DAB was demonstrated to be removable by nitrifying biomass, which suggests that the combination of a MEC and bio-Pd in its cathode offers potential to dehalogenate pharmaceuticals, and to significantly lower the environmental burden of hospital waste streams.

Noninvasive monitoring of photocatalytic degradation of X‐ray contrast media using Raman spectrometry

“…Studies showing the residence of polycyclic aromatic hydrocarbons, hormones, prescription and over the counter drugs, and other medical wastes have led to many alternative approaches to treatment. Iodinated X‐ray contrast media such as diatrizoate and iohexol represent unique challenges to waste management systems . These compounds are administered to patients in very high dosages (therapeutic levels are near molar concentrations), are not metabolized by the body and are therefore excreted, largely unmodified, into the waste water stream .…”

“…These compounds are administered to patients in very high dosages (therapeutic levels are near molar concentrations), are not metabolized by the body and are therefore excreted, largely unmodified, into the waste water stream . As a result, waste management systems near medical facilities are often faced with large spikes in the concentrations of these compounds …”

Palladium nanoparticles produced and dispersed by Caldicellulosiruptor saccharolyticus enhance the degradation of contaminants in water

“…20 Pd(0) particles have been reported frequently as the catalyst of the reduction of halides, such as trichloroethylene (TCE), chlorophenols and diatrizoate. [21][22][23][24] This study chose diatrizoate as the halide to test the catalytic activity of Pd(0) particles in extreme thermophilic condition. As shown in Fig.…”

Palladized cells as suspension catalyst and electrochemical catalyst for reductively degrading aromatics contaminants: Roles of Pd size and distribution

“…the cathode can be employed to produce H 2 in a sustainable way to provide an economical interesting reactant for bio-Pd catalyzed dehalogenation reactions. It is of great interest to examine the impact of decorated electrode on the performance of contaminants removal such as diatrizoate degradation and chlorinate hydrocarbons reduction (Hosseinkhani et al, 2013;De Gusseme et al, 2011;Hennebel et al, 2011). Studies have demonstrated that bioPd decorated electrode enhanced the efficiency of contaminants removal (Hosseinkhani et al, 2013;De Gusseme et al, 2011;Hennebel et al, 2011).…”

“…It is of great interest to examine the impact of decorated electrode on the performance of contaminants removal such as diatrizoate degradation and chlorinate hydrocarbons reduction (Hosseinkhani et al, 2013;De Gusseme et al, 2011;Hennebel et al, 2011). Studies have demonstrated that bioPd decorated electrode enhanced the efficiency of contaminants removal (Hosseinkhani et al, 2013;De Gusseme et al, 2011;Hennebel et al, 2011). However, this kind of Pd-cell have rarely been used as electrocatalyst directly because of the poor conductive nature of microbial cells Xiong et al, 2015).…”