325 J. Indian Chem. Soc., Vol. 95, March 2018, pp. 325-330 Determination of extent of antibiotic resistance bacteria in wastewater and removal of antibiotics using UV-H 2 O 2 process Krishanu Hait a1 , Asok Adak a , Bijoli Mondal a and Pallab Datta b a Department of Civil Engineering, b Center for Healthcare Science and Technology, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711 103, West Bengal, India E-mail : krishanu.hait@gmail.com Manuscript received 15 November 2017, revised 26 February 2018, accepted 13 March 2018 Abstract : Emerging contaminants (ECs), like antibiotics in wastewater has drawn much attention in recent years. Several studies reported development of antibiotics resistant pathogenic strains due to long-term expo- sure of various antibiotics. The present studies show that the EC 50 (measure of compound’s 50% inhibition on bacterial growth) for the antibiotics on E. coli is on higher magnitude than environmentally significant concentrations. While checking for EC 50 for E. coli against fluoroquinolone antibiotics (ciprofloxacin (CIP) and ofloxacin (OFL) in different municipal and hospital wastewater, the observed values were that E. coli isolated from municipal wastewater exhibits 4 to 11 times fold resistance whereas in case of hospital waste- water E. coli exhibits around 14 to 30 times fold resistance. In the degradation study of antibiotics, the re- sults exhibit direct photolysis was found to be very slow compare to UV-H 2 O 2 process in degrading the anti- biotics, only 17% for CIP and 12% for OFL was observed through direct photolysis. Whereas, for the UV- H 2 O 2 process, more than 80% transformation of antibiotics was achieved with peroxide dose of 5 mol H 2 O 2 / mol antibiotics within 60 min at pH 7. Keywords : Antibiotics, E. coli, Ciprofloxacin, Ofloxacin, UV, UV-H 2 O 2 . I. Introduction Over the past decades the occurrence, fate, and risks of residual antibiotics in the environment have become apparent as an emerging concern 1 . Though release of these contaminants into the environment has been occurring for quite some time, but methods for their detection at environmentally-relevant con- centrations have only recently become available. Several recent studies on emerging contaminants (ECs) like antibiotics are directed towards under- standing their environmental fate due to the associ- ated hazards 2 . Antibiotics are chemical substances which have capability to deactivate or kill other mi- croorganism, generally infection causing bacteria; even they are very active in a very low concentra- tion 3 . On the basis of chemical structure of antibiot- ics, they can be classified into different classes like -lactam : amoxicillin and Penicillin G; fluoro- quinolone : Ciprofloxacin and Ofloxacin; Macrolide : azithromycin; sulfonamide : Sulfadoxine; and tetra- cycline : tetracycline. Now a day’s certain serious side effects of antibiotics have been observed due to emergence of antibiotic resistance bacteria. The wide application of antibiotics in human and veterinary medicine has led to a large-scale dissemination of bacteria resistance to antibiotics in the environment. This leads to an increase in the percentage participa- tion of antibiotic resistant bacteria in various environ- ments causing problems in therapy by selecting re- sistant bacteria. An international level of investiga- tion made by southern Austria in sewage, sludge and receiving waters from three different STP said that a total 767 E. coli were isolated and tested regarding their resistance to 24 different antibiotics. The high- est resistance rates were found in E. coli strains of a STP which treats hospital sewage 4 . A national level