Bioaugmentation was applied by introducing marine halophilic bacteria into an intermittently aerated biological filter (IABF) to improve the removal of nutrient pollutants from hypersaline synthetic wastewater (salinity: 3-13%). The bio-enhanced IABF showed improved performance on nutrient removal in the salinity range of 4-10% compared with the control IABF. The enhancement of eliminating chemical oxygen demand, total nitrogen and total phosphorus peaked at salinities of 7-10%, 7-9% and 5-7%, respectively, where the corresponding removal efficiencies were increased by about 8.6%, 15.7% and 17.3%, respectively. Inoculation with marine bacteria improved the degradation of nitrogenous organics and denitrification in nitrogen transformation. In hypersaline environments biofilter recovery after back-washing was significantly prolonged whereas the time required in the bio-augmented IABF was comparatively short. The results of dehydrogenase activity assays demonstrated that inoculation with marine bacteria improved the activity of biofilm in hypersaline environments. (C) 2012 Elsevier Ltd. All rights reserved.