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Biological Aerated Filters (BAF) systems have been applied in about 500 treatment plants worldwide, especially for upgrades of plants in limited areas and for nitrogen removal and some plants serve major European cities such as Manchester, Oslo, Paris and Rome. Nevertheless, some process limitations have prevented even more widespread acceptance. The backwash system to assure the daily removal of excess biomass adds significant cost and operator constraints.

To alleviate these drawbacks, several strategies are presented to increase the removal performance of biofilm plants:

– the reduction of the solids load to the bioreactor by increased pre-treatment, such as chemically enhanced primary treatment and recycle of biosolids

– the reduction of backwash needs by a more open media, such as the development of the Submerged Aerated Filter (SAF), with less solids retention in the media

– the intensification of backwash and re-arrangement of backwash program to optimise the solids extraction from the filters and

– the optimisation of SAF and downstream BAF or DBF in series

Examples of pilot and full scale plants as well as their operating results are given.

Document Type: Research Article


Publication date: January 1, 2005

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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