Photoelectrocatalytic inactivation of fecal coliform bacteria in urban wastewater using nanoparticulated films of TiO₂ and TiO₂/Ag

Abstract

Photocatalysis has shown the ability to inactivate a wide range of harmful microorganisms with traditional use of chlorination. Photocatalysis combined with applied bias potential (photoelectrocatalysis) increases the efficiency of photocatalysis and decreases the charge recombination. This work examines the inactivation of fecal coliform bacteria present in real urban wastewater by photoelectrocatalysis using nanoparticulated films of TiO and TiO/Ag (4%w/w) under UV light irradiation. The catalysts were prepared with different thicknesses by the sol-gel method and calcined at 400°C and 600°C. The urban wastewater samples were collected from the sedimentation tank effluent of the university sewage treatment facility. The rate of bacteria inactivation increases with increasing the applied potential and film thicknesses; also, the presence of silver on the catalyst surface annealed at 400°C shows better inactivation than that at 600°C. Finally, a structural cell damage of Escherichia coli (DH5α), inoculated in water, is observed during the photoelectrocatalytic process.

Photo-assisted electrochemical advanced oxidation processes for the disinfection of aqueous solutions: A review

“…As expected, the presence of Ag was identified to significantly increase the response of TiO 2 towards bacterial inactivation. Upon an applied cell potential of 1.5 V the TiO 2 /Ag (4% w/w) photo-anode also achieved complete inactivation of fecal coliform bacteria in the solution within 6 min ( Domínguez-Espíndola et al., 2017 ). Brugnera et al.…”

“…Ag also alters the transport system within the cell membrane resulting in catastrophic permeability, osmoregulation, electron transport and respiration events that eventually lead to cell death ( Mafa et al., 2020 ). Domínguez-Espíndola et al. (2017) and Domínguez-Espíndola et al.…”

Photocatalytic Treatment of Pharmaceuticals in Real Hospital Wastewaters for Effluent Quality Amelioration

“…Fe-doped g-C 3 N 4 and P-doped g-C 3 N 4 for wastewater treatment have been synthesized [32,33]. In addition, various works concerning the photocatalytic treatment of real effluents with the use of TiO 2 , g-C 3 N 4 , Ag/g-C 3 N 4 , TiO 2 /Ag and g-C 3 N 4 /TiO 2 /Fe 3 O 4 @SiO 2 have been conducted in recent years [34][35][36][37]. For instance, studies using heterojunctions of g-C 3 N 4 like TiO 2 /g-C 3 N 4 for Cr(VI) removal [38] and Ag/Ag 3 VO 4 /g-C 3 N 4 for the degradation of tetracycline in wastewaters have been published [39].…”

Recent Overview of Solar Photocatalysis and Solar Photo-Fenton Processes for Wastewater Treatment

“…1% DOC removed and~50% COD abatement (at 180 min) [102] Water from a natural source (Pance River in Cali, Colombia) and spiked with E. coli (5.5 mg L 20% and 85% of TOC were removed at pH 7.5 and 2.5, respectively (at 45 min) [104] 3 International Journal of Photoenergy The COD was abated smoothly up to 68% COD decrease after 90 min of Fenton reaction (1.6 h) [193] The hydrogen peroxide is generated in situ from the twoelectron oxygen reduction on cathodes such as reticulated vitreous carbon [46], gas diffusion electrodes [47], carbon felt [48,49], pristine graphene [50], and boron-doped diamond [51] from reaction (12), and Fe 2+ can be electrochemically regenerated, if it was initially added to the solution (reaction (13)) or electrochemically generated from a sacrificial iron anode (reaction (14) , enhanced by the photodecarboxylation of ferricarboxylate complexes under UV-visible light, followed by a very slow reaction rate with a low consumption of H 2 O 2 due to the disappearance of oxalic acid and free iron species complex with other organic oxidation by-products which reduced substantially the dissolved iron concentration and consequently the reaction rate [35].…”

“…These two AOP have proved to be very effective for degrading a vast aqueous organic contaminants such as emerging [2,3], persistent [4][5][6][7][8][9], textiles [10][11][12][13], and bacteria [14][15][16] pollutants.…”