Feasibility study of complete nitrogen removal from domestic wastewater by consequent nitrification-denitrification using immobilized nitrifiers in gel beads
A two-stage process for complete removal of nitrogen from domestic wastewater is proposed in this paper. The two stages of this process are an aerobic stage using nitrifying microorganisms immobilized in gel beads and a conventional 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 assumption s were confirmed in the present work: (a) substances present in domestic wastewater do not inhibit nitrification, and (b) heterotrophic biomass that builds up on the surface of nitrifying beads is not expected to affect ammonium oxidation or remove a significant part of the biochemical oxygen demand required for denitrification. The effect of the attached heterotrophic layer on system performance was evaluated through theoretical prediction and short-term experiments. Calculations indicated that complete nitrogen removal could be achieved if the heterotrophic layer on 2-mm gel beads is less than 12 {micro}m thick. The heterotrophic biofilm observed in the experiments did not homogeneously spread over the entire bead surface. It was found that attached growth of heterotrophs is affected by mixing intensity and type of carrier material.
- OSTI ID:
- 20014586
- Journal Information:
- Water Environment Research, Vol. 72, Issue 1; Other Information: PBD: Jan-Feb 2000; ISSN 1061-4303
- Country of Publication:
- United States
- Language:
- English
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