Image: Biomass-based model biofilm (coupled)
Biofilm, aged 96,000 min (67 days, 9.5 weeks). The contour lines show the oxygen concentration in mg/l. The image was rendered with POV-Ray, showing each biomass brick as a sphere. The biomass of the ammonia oxidisers ("Nitroso") is green; the biomass of the nitrite oxidisers ("Nitro") is red. These colours were chosen in order to make the overlapping of biomasses of the two species easily visible. The grey box at the bottom is the inert substratum. Note the wrapped around boundaries in the horizontal direction.
This Biomass-based model version (coupled) allows the coexistence of biomasses of the two species in the same grid element. Spreading of the two species is coupled if they exist in the same grid element.