Applying cake filtration theory on membrane filtration data

Conventional cake filtration theory is used in this paper to analyse membrane filtration data on activated sludge published by Benitez et al. (1995). In contrast they used boundary layer modelling for handling the data. Firstly the conventional cake filtration theory is shown to be equivalent to the boundary layer model in principle but more complete in its description. Secondly the data analysis is performed and a systematic deviation, which cannot be explained, seems to be involved in the data used. The data are corrected for this and reanalysed according to conventional cake filtration theory. The activated sludge is shown to be highly compressible.