Particulate-biofilm, expanded-bed technology for high-rate, low-cost wastewater treatment: Nitrification

Dempsey, Michael J. (2005) Particulate-biofilm, expanded-bed technology for high-rate, low-cost wastewater treatment: Nitrification. Water research, 39 (6). pp. 965-974. ISSN 0043-1354

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Abstract

The performance of a particulate-biofilm, expanded-bed process for nitrification of activated sludge final effluent (ASFE) is reported for a plant receiving mixed industrial and domestic wastewater. The support material for the particulate-biofilms was glassy coke, to which the nitrifying bacteria attached and formed a highly active biofilm. An average nitrification rate of 1.7±0.6 kg m−3expanded bed d−1 was recorded during operation of the bioreactor, which had a hydraulic residence time of 15 min. On average, the ASFE contained 12.6±3.7 g m−3 NH3–N, which was reduced to 2.6±3.3 g m−3 NH3–N. Furthermore, transfer of 10–12% of the oxygen in air was achieved using counter-current aeration. This investigation has demonstrated that a high rate of nitrification can be achieved with a particulate-biofilm, expanded-bed process. It has also demonstrated that the process can operate without backwashing and still remove particulate material from the ASFE feed.