System and method for cultivation of oxygenic photogranule

A method comprising the steps of:

• flowing a mixture comprising a water-based reaction medium and at least one microalgae into a reaction vessel at a continuous or substantially continuous flow rate, wherein the water-based reaction medium comprises a nutrient material that is consumable by a live microalgae, by a live bacterium, or by a live protozoa present in the water-based reaction medium;
• incubating the mixture in the reaction vessel, wherein the incubating comprises agitating the mixture under specified agitation conditions while exposing the mixture to at least intermittent illumination with a specified luminous flux during periods of illumination such that the microalgae forms a supporting matrix that incorporates the live microalgae, the live bacterium, or the live protozoa into a biologically-active bioaggregate granule, wherein the incubating produces an incubation mixture comprising a plurality of the biologically-active bioaggregate granules, wherein the incubating of the mixture does not include artificial aeration of the mixture;
• and
• selecting out a first specified portion of the biologically-active bioaggregate granules from the incubation mixture that are smaller than a first specified size or below a first specified weight and removing the first specified portion of the biologically-active bioaggregate granules in an effluent stream or selecting out a second specified portion of the biologically-active bioaggregate granules from the incubation mixture that are larger than a second specified size that is larger than the first specified size or over a second specified weight that is larger than the first specified weight and removing the second specified portion of the biologically-active bioaggregate granules in the effluent stream.