Removal of recalcitrant organic substances in livestock wastewater using ozonation and an electrochemical process

This study examined the effectiveness of an ozone (O₃) system from an existing livestock wastewater treatment plant installed with a dissolved O₃ flotation unit and suggested a method for future improvement in terms of an effective removal of recalcitrant organic substances. An optimum O₃ dose was proposed by selecting an O₃ dose yielding a maximum value of biochemical oxygen demand/chemical oxygen demand (BOD₅/COD_Mn). The peroxone (O₃/H₂O₂) process was found to be no different of efficiency from the O₃ alone process due to the high alkaline content of the wastewater in which all hydroxyl radicals (OH^•) are scavenged. In this study, an electrochemical process was found to be promising in decreasing the recalcitrant organic substances and the removal efficiency of them was not affected by the timing of ozonation, i.e., as a final step.