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

Abstract

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

Effects of pH and seasonal temperature variation on simultaneous partial nitrification and anammox in free-water surface wetlands

“…The free-water surface wetlands had low redox potentials and dissolved oxygen concentrations (Table 1), indicating conditions that were suitable for coupling partial nitrification and anammox (Gaul et al, 2005;Tao et al, 2011;van der Star et al, 2007). Microorganisms in free-water surface wetlands may attach to sediment particles, plant stems, and litter, forming biofilms.…”

Anammox enrichment from reject water on blank biofilm carriers and carriers containing nitrifying biomass: operation of two moving bed biofilm reactors (MBBR)

“…7) was constructed to show the phylogenetic relationships between the two anammox microorganisms detected in the systems and other anammox microorganisms including ''Brocadia fulgida'' and Candidatus ''Kuenenia stuttgartiensis''. Gaul et al (2005) have suggested that Brocadia strains, e.g. ''Brocadia anammoxidans'' strains are highly inhibited by elevated NO 2 -concentrations, and therefore they are not enriched in reactor systems of high -concentration, which temporarily occurred in our system.…”

“…Various methods have been employed to culture and enrich anammox biomass, e.g. anammox biomass has been enriched from different types of inoculums-sludge from anaerobic (Tsushima et al 2007a) or nitrifying/ denitrifying reactors (Jeanningros et al 2010;Desloover et al 2011;Gaul et al 2005;Tang et al 2010b). To our knowledge enrichment of anammox microorganisms directly from wastewater on biofilm carrier elements without using seeding sludge has not been reported in previous studies.…”

“…In anammox biofilm reactors TN rates have been 24,000 g-N/m 3 /day (Tsushima et al 2007b). However, moving bed biofilm reactor (MBBR) configuration is determined to be effective for anammox enrichment (Gaul et al 2005). Advantages of the MBBR in both technological applications and lab-scale experiments (Ling 2009;Rosenwinkel and Cornelius 2005;Schneider et al 2009) include compactness, tolerance to inhibiting substances and avoiding biomass loss from the deammonification process.…”

Influence of the shear stress and salinity on Anammox biofilms formation: modelling results

“…This is an advantage because the production of surplus sludge is reduced; however, it also implies that the process must be operated in reactors with very good sludge retention. Some of the systems used to improve biomass retention are based on biofilm reactors, either with moving bed carriers [2][3][4][5][6] or fixedbed systems [7][8][9][10]. The formation of bacterial biofilms must, necessarily, begin with the adhesion of a small number of bacterial cells to a surface [11].…”