Abstract
Nitrifying bacteria acclimated to tolerate concentrations of ammonium sulfate as high as 5300 mg/L were prepared from activated sludge (AS) or effective microorganism groups (EM) and physically immobilized on polymeric spherical hydrogel (KU, AL, AL [C], AL [F]), polymeric cubic hydrogel (ALCu, ALCu [C]), pelletized polypropylene (BCP [C]), or cylindrical polypropylene (ALT, ALT [C]). The supports AL [C], BCP [C], ALCu [C], and ALT [C], contain activated carbons (C), and AL [F] contains fly ash (F). Entrapped bacteria were also prepared by the crosslinked gelation of poly (vinyl alcohol) (PVA) with boric ion in the presence of C, F, or activated alumina (Al) to yield PVA [C], PVA [F], or PVA [Al], respectively.
Removal of high concentration of ammonium with acclimated nitrifying bacteria and stripping from model wastewater were carried out. Interestingly, entrapped bacteria produced NO3− from NH4+ in series, while AS/PVA and physically immobilized bacteria produced only NO2− from NH4+. In the case of high concentration of ammonium load, the acclimated bacteria cultured from EM/PVA [C] (bacteria/support) or AS/ALT [C] were able to remove about 57% of the ammonium ions with stripping from the 5300 NH4–N mg/L model wastewater in 30 days. Complete nitrification reactions were examined by using immobilized bacteria, NO2−-producing AS/ALT [C] and NO3−-producing EM/PVA [Al]. High concentration of NH4+ was almost completely nitrified to NO2− or NO3− after 35 or 50 days, respectively.
