The researchers tested different methods to clean up wastewater from the oil recovery industry. They found that using a combination of H2O2 and Fe+2 was the most effective, reducing the COD levels by 86%. The UV/H2O2 process also helped, reducing COD by 39%. Overall, the UV/Fe+2/H2O2 process was the most efficient, removing 81% of the initial COD. The study showed that these methods can significantly reduce the pollution in industrial wastewater.