BACKGROUND: In this study, the microalga Chlorella vulgaris (FACHB-38) was cultivated in pure (3122.5 mg L-1 chemical oxygen demand (COD)) and diluted anaerobic digested starchwastewater (ADSW; 313.2, 622.8, 935.7, 1248.5, and 1558.9mg L-1 COD). This study mainly aimed to compare algal growth and tolerance with various dilutions of ADSW, as well as determine nutrient removal efficiency and role of biogas upgrade. RESULTS: Chlorella vulgaris cultured in ADSW with 935.7 mg L-1 COD yielded a maximum total biomass of 3.39 +/- 0.27 g L-1 (dry weight) and pollutant removal efficiencies of 79.04%+/- 5.71% COD and 73.19%+/- 6.98% total nitrogen (TN). The contents of C, N, and P in biomass remained constant at 48.93-50.12%, 8.76-9.94%, and 0.74-0.98%, respectively, among all dilutions. High total phosphorus (TP) removal efficiency was observed in treatments with 1248.5-1558.9 mg L-1 COD. The most appropriate dilutions for biogas upgrade were 935.7 and 1248.5mg L-1 COD. CONCLUSION: The optimal effect of nutrient removal and biogas upgrading can be obtained by appropriate control of ADSW dilution in influents. (C) 2016 Society of Chemical Industry