The production and biochemical profile, consisting of the protein, carbohydrate, lipid and fatty acid fractions of the microalgae Aphanothece microscopica Nageli, cultivated in parboiled rice effluent, were studied with the objective of evaluating its potential as a source of metabolites of commercial interest. The biomass was produced in a batch cylindrical bioreactor operating isothermally at 30 degrees C, with the pH adjusted and maintained at 8.0, an inoculum concentration of 100 mg/L and ON ratio of 50. The biomass was separated by centrifugation and dried in a batch tray dryer with parallel air flow (1.5 m/s) at temperatures of 40, 50 and 60 degrees C and tray thicknesses of 5 and 7 mm, followed by a biochemical evaluation. The results obtained showed that the parboiled rice effluent was a culture medium with potential for the production of single cell protein, and that the biomass produced represented an important source of protein, carbohydrate and lipids. The drying conditions were shown to significantly affect (alpha = 0.05) the macronutrient composition of the biomass with respect to the protein, carbohydrate and lipid contents. The lipid profile showed a predominance of polyunsaturated fatty acids, especially that of gamma linolenic acid, but the drying conditions did not influence the polyunsaturated/saturated ratio of the biomass. (c) 2007 Published by Elsevier B.V.