Biofilms  
Airlift biofilm reactors are used for treating domestic and industrial waste water. The biomass is attached on small, in the water phase suspended carrier particles (diameter 200-300 Ám). Due to this attached growth, a high biomass concentration (30 - 40 kg/m3 ) can be maintained in the reactor which allows high volumetric loadings. At loadings of about 8 kg COD/m3.day , COD removal and nitrification do occur simultaneously. Integration of an anoxic compartment in the reactor, results in denitrification as well. Compact/smooth biofilms will develop if the specific surface load does not exceed the level of about 10 g COD/m2.day.  
smofilm1.jpg (30225 bytes) Smooth and compact biofilm smofilm2.jpg (26148 bytes) Smooth and compact biofilm
detafilm.jpg (23328 bytes) detachment of old biofilms thiofilm1.jpg (36899 bytes) Surface biofilm colonised by Thiotrix
thiofilm2.jpg (42158 bytes) Surface biofilm colonised by Thiotrix thiofilm3.jpg (42075 bytes) Surface biofilm colonised by Thiotrix

fluffilm.jpg (37807 bytes) 

Fluffy biofilm (high specific surface load applied) sesfilm.jpg (26449 bytes) Sessile ciliates attached to biofilm