- Mixtures of several type, often also inhibitory pollutants, respectively
- salinities characterised by fluctuating concentrations and qualities,
resulting often in low rates and stabilities of nitrication processes, despite to efficient COD removals. Immobilisation of nitrifying biomass results generally in process improval. Example : Nitrification of an inhibitory, saline chemical effluent Nitrifying a chemical effluent, polluted with 1500 mg/L COD, 200 mg/L NH4N and 18 to 23 g/L salinity in a 1,0 m³ pilot plant reactor operated continuously at a N-loading rates of ca. LV(N) ~ 0,23 g NH4N/(L*d) immobilised organisms have nitrified ca. 95% of the NH4N-load , compared with 28% of suspended biomass (figure).
Beside that also the oxygene uptake has been compared. 60 to 70% of the oxygene has been consumed by immobilised organisms but only by 30 bis 40 % suspended biomass, being present approximately in the same quantity in the reactor.