Testing of biological aerated filter (BAF) media

The cost of filter media contributes a significant proportion of the initial capital outlay in wastewater treatment by biological aerated filters (BAFs). Media characteristics also affect day to day running costs such as those involved in backwashing. To allow an informed choice relating to filter media and their prospective uses a number of standards have been produced, most recently the British Effluent and Water Association (BEWA) standard. The aim of this study was to investigate a number of granular media using the BEWA standard in order to determine their suitability for BAFs. All the media samples investigated appear suitable for use as BAF media with one in particular having all the necessary characteristics e.g. low density, high specific surface area and resistance to attrition.