Disinfection of Effluent Using Catalytic Ozonation Process and Economical Comparison with Chlorination

Background and Many conventional disinfection methods of effluents raise some health, efficiency and economic concerns. In order to increase the efficiency of disinfection of real effluent, in this study, the catalytic ozonation process was performed and economically compared with chlorination.
Magnetic activated carbon was used as acatalyst in a semi-continuous reactor for disinfection of effluent of municipal wastewater treatment plant in Bandargaz, Iran in 2015. The efficiency of disinfection was determined by thermo-tolerant coliform as indication, and the effect of parameters such as catalyst concentration (0, 0.5, 1, 2, and 5 g/L), initial number of coliforms, contact time (1, 2, 5, 10, 20 and 40 min) and catalyst reuse on disinfection process was evaluated. Finally economic comparison was done with the chlorination.
The results showed that the efficiency of disinfection was increased by increase in the concentration of carbon nano-composite and contact time; at 1 g/L concentration of Catalyst about 1.99 log reduction was observed after 2 min exposure time in which the effluent standards were obtained; while 1.91 log reduction of micro-organisms was measured for single ozonation. The first-order kinetics constant of single ozonation (0.42 min-1) showed an approximately 9-fold increase when the catalyst (2 g/L) was added to the solution. After 7 times reuse of nano-composite, the diminution of efficiency was negligible (1.5%); and more than 57% fall of the cost was observed in a 5-year operational period compared with chlorination.
The catalytic ozonation with the new catalyst of effluent could effectively disinfect the effluent in a short-contact-time, and due to economic considerations it can be used as an effective and economical method in wastewater treatment plants.