The main pollutant in waste water discharged from a petroleum
refinery is oil (both in free and emulsified form). Free oil is removed by
(A) Biological oxygen pond
(B) Aerated lagoons
(C) Trickling filters
(D) Gravity separator having oil skimming devices
refinery is oil (both in free and emulsified form). Free oil is removed by
(A) Biological oxygen pond
(B) Aerated lagoons
(C) Trickling filters
(D) Gravity separator having oil skimming devices