Mixing method for big amount of wastewater

Hi. Good day everyone  We are planning to design a wastewater treatment plant in which a water stream of  72 cubic meters/hr containing grease (non-soluble) and small Iron Particles enters. The process consists of 1 ozonation unit with oxygen inlet, a powerful mixer, a recirculation pump which helps better oxygen dissolution and inline injection. Would anybody help me with choosing the proper mixing method for such a process. Please bear in mind that the cost of the instrument, Energy consumption, and maintenance is very important. Thanks for your time and consideration. A.Reyhan