DO vs BOD

The higher the BOD, the lower the DO present in the sample. This is caused by the organisms thriving in water, especially bacteria in polluted water such as the Grease Trap. And since the organisms in the waters require high amount of Oxygen for their activities, it results in the decrease of DO.

Given that the values of BOD are 4.75mg/L in average, it falls into the standard values of BOD of Raw Water source which is 3 to 15 mg/L.