Feasibility study of complete nitrogen removal from domestic wastewater byconsequent nitrification-denitrification using immobilized nitrifiers in gel beads
V. Libman et al., Feasibility study of complete nitrogen removal from domestic wastewater byconsequent nitrification-denitrification using immobilized nitrifiers in gel beads, WAT ENV RES, 72(1), 2000, pp. 40-49
Citations number
14
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
A two-stage process for complete removal of nitrogen from domestic wastewat
er is proposed in this paper. The two stages of this process are an aerobic
stage using nitrifying microorganisms immobilized in gel beads and a conve
ntional anoxic stage. The possible application of gel-entrapped biomass for
high-rate, complete nitrogen removal from domestic wastewater was verified
through theoretical and experimental work. Two assumptions were confirmed
in the present work: (a) substances present in domestic wastewater do not i
nhibit nitrification, and (b) heterotrophic biomass that builds up on the s
urface of nitrifying beads is not expected to affect ammonium oxidation or
remove a significant part of the biochemical oxygen demand required for den
itrification. The effect of the attached heterotrophic layer on system perf
ormance was evaluated through theoretical prediction and short-term experim
ents. Calculations indicated that complete nitrogen removal could be achiev
ed if the heterotrophic layer on 2-mm gel beads is less than 12 mu m thick.
The heterotrophic biofilm observed in the experiments did not homogeneousl
y spread over the entire bead surface. it was found that attached growth of
heterotrophs is affected by mixing intensity and type of carrier material.