A Acid mine drainage contains an acidic pH and high concentrations of heavy metals, so that when exposed to it in the environment it will have adverse effects such as disrupting soil quality and water quality. This study aims to 1) determine the growth response of mixed culture of Chlorella sorokiniana and Monoraphidium neglectum microalgae in AMD; 2) determine the optimum environmental conditions, namely contact time and biosorbent concentration which affect the biosorption of heavy metals in AMD; 3) determine the efficiency of heavy metal removal of Manganese and Iron in AMD by the biosorbents Chlorella sorokiniana and Monoraphidium neglectum. Mixed culture of microalgae was cultivated on Provasolli Haematococcus Medium (PHM) with batch system. In this study, artificial AMD contained 5.37 mg/L of Manganese metal and 1.13 mg/L of Iron metal. The Erlenmeyer flask was placed in an incubator shaker with a rotating speed of 150 rpm, a temperature of 30°C, variations in contact time (minutes) 60, 120, and 180 and variations in the concentration of biosorbent (%) 10, 20, and 30. The effectiveness of the biosorbent was analyzed by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), Fourier Transformed Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The results showed that the addition of 20% biosorbent for 120 minutes provided the highest removal efficiency of Manganese and Iron, reaching 96.2% and 86.3%, respectively. The process of biosorption of Manganese and Iron metals was followed by a gradual increase in pH from 1.65 to 5.89. The results of the FTIR analysis provide information that the carboxylic acid and alkane functional groups are the most important functional groups in the biosorption process as evidenced by their weaker intensities. SEM analysis proves that the biosorbent undergoes morphological changes, marked by cracks on the surface that allow the absorption of heavy metals. The isotherm model suitable for this study is the Langmuir isotherm and second order adsorption kinetics. This study shows that the mixed culture of microalgae Chlorella sorokiniana and Monoraphidium neglectum can be an effective biosorbent for removing the heavy metals Manganese and Iron which pollute the environment.