High-yield production of biomass, protein and pigments by mixotrophic Chlorella pyrenoidosa through the bioconversion of high ammonium in wastewater

•Mixotrophic C. pyrenoidosa could grow well in high NH4+-high salinity wastewater.•Maintaining a low C/N ratio below 5 is a pivotal strategy for high ammonium removal.•Maximum NH4+ consumption rate (1800 mg L-1 d-1) is achieved in 50-L photofermenter.•Photofermentation is a novel strategy to convert high ammonium to high-value biomass.