Otadi - Young researcher Club of Islamic Azad University, Science and Research Branch of Tehran- Department of Environmental Engineering and energy
Hassani - Islamic Azad University, Science and Research Branch of Tehran- Department of Environmental Engineering and energy
Javid - Islamic Azad University, Science and Research Branch of Tehran- Department of Environmental Engineering and energy
Khiabani - MSc Student in Environmental Sciences, University of East Anglia, England

The aim of this research is inspecting the efficiency of physical-chemical and biological processes with the active sludge method in the crude (raw) waste water of the Pars Oil Refinery Company. This research was done from 26th, January 2007 and continued up to 27th, May 2007. The main operation in Pars oil refinery is to produce lubricants. This research tries to examine and evaluate the performance of treatment system at the refinery to decrease microorganism in the industrial wastewater in a laboratory scale pilot. The pilot has two sections; physical-chemical section, including Dissolved Air Flotation system, and biological section, including wastewater and clarifier. This investigation carried on a 10 liters Dissolved Air Flotation reactor and an active sludge reactor in a laboratory scale. The volume of the aerireactor (aeration reactor) was 10 liters, and the volume of the secondary sediment was 3.5 liters. The waste water of the refinery was used as inlet flow of pilot and necessary sludge was obtained at first from the Shahrak Ekbatan waste water treatment system. After analyzing the test results, it was concluded that the average percentage of excluding oil, Chemical Oxygen Demand and Biological Oxygen Demand is 29.7, 49 and 27.8 respectively. This indicates the effective role of physical treatment in decreasing oily emulsion material that would result in decreasing organic density in untreated wastewater. In biological system, the efficiency of excluding Chemical Oxygen Demand and Biological Oxygen Demand is 73.4 and 84.7, respectively. This confirms high efficiency of this unit. The samples taken from entering (influent) and exiting (effluent) wastewater of both units were tested. Standard Methods was applied to determine the considered physical and chemical parameters.

Activated sludge, Aerireactor, Dissolved Air Flotation, Oil Refinery