ENV-01-13 Impact of Oil Loads on the Performance of Powdered Activated Carbon – Activated Sludge Treatment of Refinery Wastewater

Description:

The study examined the impact of changing influent oil concentration on the quantity of powdered activated carbon (PAC) needed to achieve acceptable reductions of effluent chronic toxicity associated with refinery wastewater activated sludge treatment. The paper presents results of a PAC-activated sludge pilot-scale treatability study conducted at a mid-western petroleum refinery. The study documented that increases in influent oil levels over typically recommended concentrations will result in major increases in the PAC doses needed to achieve acceptable process performance for the reduction of effluent chronic toxicity as determined from seven day whole-effluent bioassays with Pimephales promelas (fathead minnow). The apparent PAC usage for a condition where a dissolved air flotation (DAF) unit was removed entirely from service resulted in a tripling of the powdered carbon requirement for operation of the PAC-activated sludge process. The predicted range of PAC usage was increased from 530 tons/yr. to 1580 tons/yr. for a 30-day sludge age operating condition. If a 20-day sludge age operating condition were used for management of the PAC-activated sludge process, the powdered carbon usage would increase again by more than 50 %.