The removal of total dissolved phosphate by the cyanobacteria Aphanothece microscopica Nägeli cultivated heterotrophically in dairy processing wastewater was investigated in this work. The experiments were carried out in bioreactors operating in a batch mode, fed with 4.5 L of wastewater. The experimental conditions were as follows: initial cell concentration of 0.2 g/L, pH adjusted to 7.6, isothermal reactor operating at temperatures of 10, 20 and 30ºC with absence of light and continuous aeration of 1 VVM. The results showed that phosphate removal is strongly dependent on process temperature. A. microscopica Nägeli was effective in the removal phosphate achieving removal rates of 3.77 mg/L.h, which reflected in the conversion of 98.4% in hydraulic detention times of 24 h.
microalgae; heterotrophic bioreactor; phosphate; dairy processing wastewater