Two microalgae species (Chlorella vulgaris and Chlorella protothecoides) were tested at lab scale in order to select the optimal conditions for biomass production and the efficient remediation of effluents from poultry and pig industries. Both microalgae showed biomass productivities in the agro-industrial effluents that were comparable to the Chlorella synthetic medium used as control. C. protothecoides presented the higher productivities both for poultry effluents (46.13 and 41.75 mg.L−1.day−1 for raw and flocculated effluents) and for pig manure (95.86 mg.L−1.day−1). The supplementation of pig effluents with biomass ash increased by 50 % the microalgae productivity with the highest results obtained for C. protothecoides and C. vulgaris at ash concentrations of 1.5 g/L and 3.0 g/L, respectively. The optical density of both effluents was efficiently reduced by both microalgae but particularly by C. protothecoides and in the presence of added ash, indicating that significant reductions of suspended solids and organic matter occurred. The results showed that poultry and pig effluents may be efficiently remediated with microalgae and the fortification with biomass ash benefits the process.