BACKROUNDRecently the utilization of microalgae for biological nutrient and organic load removal from industrial wastewater streams has been of great research interest. This present research aimed to develop a biological (algal) second cheese whey wastewater (SCWW) treatment system able to generate renewable energy in the form of biodiesel while simultaneously removing polluting nutrients and chemical oxygen demand (COD). RESULTSAerobically-treated SCWW was diluted in water (dilution factor from 0.05 to 0.35) and evaluated as a substrate for Choricystis-like algal growth under photoheterotrophic conditions. Specifically, the algal culture was studied under non-aseptic conditions for its ability to remove COD, nitrogen, and phosphorous from SCWW and to produce biodiesel. At the end of treatment the pollutant load of COD, TN and PO43- was reduced by up to 92.3%, 97.3%, and 99.7%, respectively. The lipid content of the algal biomass ranged from 9.2 to 13.4%, which corresponds with an oil production of 60.8-119.5 mg L-1. The proportions of saturated and mono-unsaturated fatty acids in the lipids produced reached 79%, thus making the system suitable for biodiesel production. CONCLUSIONSA well-adapted Choricystis-like consortium could be efficiently used to treat SCWW while the biomass produced may be harnessed as a source of biodiesel. (c) 2015 Society of Chemical Industry