Mathematical modeling of E. coli inactivation in water using Fe-TiO2 composite in a fixed bed reactor

•Water disinfection was done using fixed-bed batch reactor.•Waste material like FS and FA was used to make the Fe-TiO2 composite.•Dual technique showed prominent results up-to 30 recycles. An inexpensive Fe-TiO2 composite fabricated via mixing clay with foundry sand (FS) and fly ash (FA), for the in-situ disinfection of E. coli. The continuous leaching of iron at acidic conditions into the solution through the composite and the TiO2 photoactivity on the surface of Fe-TiO2 composite beads exhibited an in-situ dual effect of photocatalysis and photo-Fenton in the treatment system. In this research work comparison of five different processes (UV irradiation; H2O2 with UV irradiation; TiO2 assisted photocatalytic technique; photo-Fenton and dual-technique (photocatalysis + photo-Fenton) using three different kinetic models were done. Kinetic studies showed more than 2 times of increase in the reaction rate with a log reduction of 6.4 only in 90 min of treatment time, thus proves the faster rate of disinfection. 18% of synergy was observed with dual effect over photocatalysis and photo-Fenton. The composite beads were recycled 30 times and only 11% reduction in the photoactivity of the catalyst was observed. Thus the obtained results present a promising potential of the dual technology for the treatment of E. coli in water.