The wastewater generated from centrifuging activated sludge, named centrate, contains highest amount of ammonia nitrogen and active phosphorus among several wastewaters after different processes in municipal wastewater treatment plant, which could be used as a valuable growth media for microalgae for the dual purpose of removing nutrients and obtaining a feedstock for biofuel production. This research was conducted step by step, resolving question by question which might account for the inhibition of fast algal growth in the centrate. Finally, the conclusion that all the possible inhibitions of (1) residual polymer, (2) unbalanced N/P ratio, and (3) deficient trace element Zn were not present was made. Algae could grow well in 100% centrate without any addition of supplementary elements. Further study will focus on scale-up, algal lipid content analysis.