Enhanced efficiency of dissolved air flotation for biodiesel wastewater treatment by acidification and coagulation processes

► Biodiesel wastewater was treated by DAF with acidification and coagulation. ► Grease & Oil removal efficiency by DAF with coagulation and alum was 85%-95%. ► DAF with acidification and coagulation was greater effective than other processes. ► Thus, acidification and coagulation could be enhanced the efficiency of DAF.