INACTIVATION OF KLEBSIELLA PNEUMONIAE IN SEWAGE BY SOLAR PHOTOCATALYSIS AND INVESTIGATION OF CHANGES IN ANTIBIOTIC RESISTANCE PROFILE

摘要

The constant presence of various and virulent microorganisms in sewage imposes the application of proper and efficient disinfection techniques in order to control possible transmission of waterborne diseases. Klebsiella pneumoniae is considered as an emerging human pathogen and can be found in wastewater, but it has been merely studied as far as its resistance against disinfection is concerned. It is an enteric, gram-negative, lactose-fermenting bacillus with a prominent capsule, recognized as an opportunistic pathogen, well known for its ability to develop resistance profiles against various antibiotics. The objectives of the present work were (i) to investigate the efficiency of cobalt- and manganese-doped titania materials to inactivate K. pneumoniae in real wastewater under solar radiation, (ii) to study the catalysts efficiency under natural sunlight, (iii) to compare inactivation rates between solar photocatalysis and chlorination and (iv) to study possible changes in K. pneumoniae antibiotic resistance profile through treatment.Dopants significantly enhanced the photocatalytic activity of TiO_2 under solar irradiation, in terms of K. pneumoniae inactivation. The process was retarded under natural solar light and longer periods were required for total bacterial removal from the reaction solution. Catalysts with the binary dopant exhibited the best photocatalytic activity in all cases, highlighting the fact that composite dopants induce a synergistic effect. On the other hand, chlorine concentrations ranging from 0.05 to 0.3 mg/L proved to be satisfactory for an overall 7-Log reduction of K. pneumoniae population after 90 min of treatment. Nevertheless, the possible production of toxic by-products during chlorination raises certain concerns regarding this method and its use for wastewater disinfection. The effect of disinfection on bacterial antibiotic resistance profile and on MICs varied, depending on the tested antibiotic and on the applied treatment method. Further research is required for the application of effective treatment/disinfection methods for the complete inactivation/elimination of ARB in WWTPs.