Display omitted •S.obliquus and C.vulgaris growth on organic waste + sludge digestate was assessed.•C. vulgaris showed best growth performances in mixotrophic conditions.•Ammonia removal reached was greater than 96% after 8 days in all mixotrophic conditions.•Similar microalgae growth was observed on centrifugated and filtrated digestate. In this research Scenedesmus obliquus and Chlorella vulgaris growth was tested on digestate sludge obtained from the anaerobic co-digestion treatment of the organic fraction of municipal solid waste (OFMSW) together with waste activated sludge (WAS). Digestate was diluted 1:10 and tested in three batch experimental conditions: with no pre-treatments (noPT), after centrifugation (AC) and after filtration (AUF), in order to evaluate microalgae limiting growth factors. The best growth was obtained by C. vulgaris on digestate AC compared to S. obliquus, reaching 479 ± 31 cell million ml−1 and 131 ± 12 cell million ml−1 respectively. Ammonia removal evaluated in C. vulgaris and S. obliquus cultures was 99.2% ± 0.3 and 98.146% ± 0.008 in AC condition, respectively. Considering that AUF showed similar microalgae growth values, the digestate pretreatment for microalgae growth, could be limited to centrifugation.