Start-up of moving bed biofilm reactors for deammonification: the role of hydraulic retention time, alkalinity and oxygen supply

摘要: Aerobic and anaerobic ammonium oxidation can be combined in a completely mixed moving bed biofilm reactor, allowing for single-stage removal from wastewater with low COD/N ratio unsuitable conventional nitrification/denitrification processes (‘deammonification’). Mandatory preconditions are: (a) hydraulic retention time to wash out suspended cells competing mass transfer limited alkalinity as limiting substrate; (b) an oxygen flux adapted the surface loading rate prevent complete nitrification nitrate. pH control or ‘NH3 inhibition’ of nitrite are neither useful nor necessary. By this strategy, biofilms simultaneous presence NH4-N NO2-N were enriched, which allowed growth oxidizers. It could demonstrated that deammonifying reactor purposefully started up within reasonable span without prior inoculation, if explicitly described strategy is applied. Depending on air flow rate, N rates 4–5 g N/m2 d achieved at DO concentrations between 1.0 4.0 mg/l.