COST-EFFECTIVE CO-TREATMENT OF SPENT AIRPORT DEICING CHEMICALS AND MUNICIPAL WASTEWATER

Using primary treated municipal wastewater from the Gardermoen WWTP as a nutrient and buffer source, deicing fluid runoff from the Oslo airport was pre-treated in lab-scale and pilot-scale moving bed biofilm reactors (MBBR). At temperatures of 8-9 °C and organic loads up to 23 g total COD/m2/d in the biofilm reactors, subsequent coagulation with 280 to 340 mL PAX-21/m3 wastewater, followed by DAF separation, produced a pre-treated effluent suitable for discharge to the biological stage at the municipal WWTP. Substituting the primary treated wastewater with a nutrient and buffer solution was unsuccessful, and produced an unacceptable DAF effluent. Treatment at very low temperature (3.5 °C) also resulted in higher than desired effluent concentrations. The temperature in a new pretreatment plant should therefore be kept as high as possible. This means that the cold deicing fluid runoff should be mixed with as much of the warmer, primary treated wastewater as possible.The municipal WWTP has a vacant DAF train that may be used for a new pre-treatment plant. The pilot-scale and lab-scale tests validated the design values originally used for a cost comparison of different alternatives, and thus confirmed that the optimum solution for a new pre-treatment plant for deicing fluid runoff will be a plant that is fully integrated with the municipal WWTP.