Reduction of COD by activated carbon in wastewater treatment of the oil refinery

In some refineries because of cold weather and lack of necessary accessories, aeration basins may not have desired performance, so often the output of the waste water recovery unit does not comply with environmental standards and regulations. Therefore, using the adsorption units of activated carbon has been proposed for reduction of organic compounds to control the COD of the waste water unit in emergency conditions. In addition, application of the adsorption units is an economic and simple technology for oily waster water treatment. In this research, three kinds of available activated carbon named LGAS 85, an Iranian made product, and two commercial activated carbons of AQASORB 2000, AQASORB 1000, are chosen and examined on the output effluent of the dissolved air flotation (DAF) unit of the oil refinery, comparatively. The removal of the pollutants in term of chemical oxygen demand (COD), at the constant temperature of 30 °C, showed almost identical performance at the batch conditions around 80% COD reduction of DAF effluent. As the LGAS 85 is an Iranian product with a price of one third of the other activated carbons, it was candidated for the detail experiments and determination of COD adsorption parameters. The experiments were carried out in the batch system at various COD concentrations and two different temperatures of the DAF effluent and sand filter outlet to derive the appropriate isotherm model. In conclusion, this kind of activated carbon would be an appropriate alternative for lowering the COD of oil refinery waste water to the environmental regulation at the temperature ranges of 20 to 40 °C , especially when there is occurred any problem in the biological aeration basin of the refinery waste water unit.