Claim: How the biogranules are produced by the filamentous and motile cyanobacteria from a source of activated sludge exposed to light is still far from understood.
Evidence: How oxygenic photogranules form is far from understood, but filamentous and motile cyanobacteria seem to play an essential role in their formation. They can form over the course of several weeks from a source of activated sludge exposed to light.