Oxygenic photogranules is a new type of biogranules that has promising bioengineering applications to  wastewater treatment but how they are produced by the filamentous and motile cyanobacteria from a source of activated sludge exposed to light is still far from understood.
Oxygenic photogranules (OPGs) are a type of biological aggregate with an approximately spherical form, typically from a millimeter to a centimeter scale. Filamentous, motile cyanobacteria play a key role, but exact mechanisms have to be elucidated to be able to control the formation and properties of oxygenic photogranules and apply them to bioengineering processes. Oxygenic photogranules is a new type of biogranules that has not been applied in bioengineering processes yet. but has promising potentials to be applied in wastewater treatment. OPGs are characterized by the cloth-like layer of phototrophic organisms, predominantly filamentous cyanobacteria of the order Oscillatoriales. How oxygenic photogranules form is far from understood, but filamentous and motile cyanobacteria seem to play an essential role in their formation. Cyanobacteria are enriched from the activated sludge and form the outer layer of photogranules that gives structural integrity for both photogranules generated under hydrodynamic and static conditions. 
