Systems and Solutions for Wastewater Treatment in the Biggest Yugoslav Oil Refinery

This paper aims at presenting the technology of wastewater treatment at the INA Oil Refinery of Rijeka applied in the past,and in the early eighties, when much stricter standards for their discharge into the sea developed a new approach to wastewater management. The refinery of Rijeka, built in the middle of the sixties, was not designed with water economy and water treatment in mind : its water consumption was very high and the polluted and clean water streams were intermixed in the combined sewer system. This resulted in high wastewater flows and in high pollutant loads per ton of crude oil. Nowadays, the wastewater treatment programme includes in-plant control measures and a modern wastewater treatment plant. The in-plant control includes the pretreatment of sour condensates and of the recirculating water, cool ing and collecting each category of wastewater in a separate sewer system. This modern wastewater treatment plant includes primary treatment, the thorough removal of emulsified oil and colloidal solids in the flocculation and flotation unit and the removal of dissolved organic materials by biological oxidation. The sludges are incinerated in a fluidized - bed type of incinerator.