Novel bioconversions of municipal effluent and CO2 into protein riched Chlorella vulgaris biomass

► Three processes of treating municipal effluent by C. vulgaris were studied. ► C. vulgaris could establish and thrive with shorter lag phases and retention time. ► C. vulgaris can consume CO2 and efficiently remove N, P, CODCr and BOD5 in the ME. ► Protein content of C. vulgaris as feedstock is 550.0 ± 30.0 mg protein·g−1 dry cells. ► Algal protein was rich in eight kinds of essential amino acids (44.5% of the total).