Biological treatment of waste water containing glycols from de-icing agents

Large amounts of de-icing agents consisting mainly of diethylene glycol and propylene glycol are used at many airports during the winter time. At modern airports a large proportion of the mixture of de-icing agents and meltwater is recycled and reused. Meltwater containing smaller amounts of de-icing agents is usually collected in retention basins and discharged into municipal sewage treatment plants. Extensive investigations have proved that waste water containing diethylene glycol may cause severe disturbances in sewage treatment. Only by avoiding shock loads and by maintaining an adapted activated sludge at the sewage treatment plant especially at a low waste water temperature can ensure that COD and BOD effluent values do not exceed critical limits.