Nutrient removal from primary wastewater effluent was tested using Galdieria sulphuraria, an acidophilic and moderately thermophilic alga. Biomass yield recorded in this study (27.42 g biomass per g nitrogen removed) is higher than the average reported in the literature (25.75 g g(-1)) while, the theoretical yield estimated from the empirical molecular formula of algal biomass is 15.8 g g(-1). Seven-day removal efficiencies were 88.3% for ammoniacal-nitrogen and 95.5% for phosphates; corresponding removal rates were 4.85 and 1.21 mg L-1 d(-1). Although these rates are lower than the average literature values for other strains (6.36 and 1.34 mg L-1 d(-1), respectively), potential advantages of G. sulphuraria for accomplishing energy-positive nutrient removal are highlighted. Feasibility of growing G. sulphuraria outdoors at densities higher than in high-rate oxidation ponds is also demonstrated. (C) 2014 Elsevier Ltd. All rights reserved.