title: Photoelectrocatalytic disinfection of water and wastewater: performance evaluation by qPCR and culture techniques.
abstract: Photoelectrocatalytic oxidation (PEC) was evaluated as a disinfection technique using water and secondary treated wastewater spiked with Escherichia coli and Enterococcus faecalis. PEC experiments were carried out using a TiO(2)/Ti-film anode and a zirconium cathode under simulated solar radiation. Bacterial inactivation was monitored by culture and quantitative polymerase chain reaction (qPCR). Inactivation rates were enhanced when the duration of the treatment was prolonged and when the bacterial density and the complexity of the water matrix were decreased. E. coli cells were reduced by approximately 6 orders of magnitude after 15 min of PEC treatment in water at 2V of applied potential and an initial concentration of 10(7) CFU/mL; pure photocatalysis (PC) led to about 5 log reduction, while electrochemical oxidation alone resulted in negligible inactivation. The superiority of PEC relative to PC can be attributed to a more efficient separation of the photogenerated charge carriers. Regarding disinfection in mixed bacterial suspensions, E. coli was more susceptible than E. faecalis at a potential of 2V. The complex composition of wastewater affected disinfection efficiency, yielding lower inactivation rates compared to water treatment. qPCR yielded lower inactivation rates at longer treatment times than culture techniques, presumably due to the fact that the latter do not take into account the viable but not culturable state of microorganisms.
authors: Department of Environmental Engineering, Technical University of Crete, Polytechneioupolis, GR-73100 Chania, Greece. danae.venieri@enveng.tuc.gr
authors: Danae
authors: D
authors: Venieri
authors: Efthalia
authors: E
authors: Chatzisymeon
authors: Eleonora
authors: E
authors: Politi
authors: Spiridon S
authors: SS
authors: Sofianos
authors: Alexandros
authors: A
authors: Katsaounis
authors: Dionissios
authors: D
authors: Mantzavinos
mesh_terms: D001431:Bacteriological Techniques; D002384:Catalysis; D004203:Disinfection / Q000379:methods*; D055664:Electrochemical Techniques / Q000379:methods*; D013293:Enterococcus faecalis; D004926:Escherichia coli; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D016133:Polymerase Chain Reaction / Q000379:methods; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*