In-situ Adaptation of Activated Sludge by Shock Loading to Enhance Treatment of High Ammonia Content Petrochemical Wastewater

Abstract

A unique method was developed to reduce high levels of ammonia in petrochemical wastewater by using a modified activated sludge process including both carbonaceous and nitrogenous oxidation. A pilot plant designed to control and measure dissolved oxygen, pH, temperature and sludge age was constructed for this study. Petrochemical wastewater which was augmented by additions of ammonia to produce concentrations up to 390 mg/l was used as the influent waste to the pilot plant. The activated sludge biomass was adapted to the influent within the reactor by using a step-function shock loading procedure. After adaptation, the pilot plant was operated in the zero sludge wasting mode which resulted in a low excess sludge production rate and the prevention of nitrifier washout. After the biomass became adapted to the influent conditions, high percentage removals of ammonia, COD, BOD, and sulfide were measured.