Cake layer reformation rates on self forming dynamic membranes and performance comparison with microfiltration membranes

Abstract

Dynamic membranes (DMs) keep on attracting attention progressively as an alternative to conventional membranes because they can be operated with relatively higher fluxes and lower fouling rates. However, there are many factors affecting the performance of DMs, such as DM pore size, structure, and operating conditions. In this study, mainly focused on the investigation of cake formation rates both in initial formation and reformation rates after physical/chemical cleaning. In this context, it has been evaluated the performances of DMs with different pore sizes (171 mu m, 90 mu m, and 30 mu m) and different structures under the same conditions and compared their performances with microfiltration (MF) membranes (0.45 mu m and 0.22 mu m) in a single reactor. In the study, the effects of different fluxes (15-, 20-, 25 L/ m(2)center dot h (LMH), SADm (1-, 0.8-, 0.5 m3-air /m(2)center dot h) and F/M (0.095, 0.125, 0.19 g-COD/g-MLSS center dot day) conditions on the treatment and filtration performance of DMs were investigated. High COD (>95%) and turbidity (<10 NTU) removals were obtained in this study. In particular, the 30 mu m DM (0.65 +/- 0.47 NTU) produced quite close effluent turbidity compared to MFs (0.12 +/- 0.05 NTU). Low SADm and high F/M values resulted in increased effluent COD concentrations and turbidity values. By decreasing the SADm, the cake formation rate and the fouling rate increased, which showed that there is a definite relationship between the cake formation rates and the fouling rates. Additionally, considering all the results, themost stable operation was obtained in the 30 mu mDM, although it has been occurred the least fouling in the 90 mu mmembrane in the study. This study, focused on cake reformation rates, attempts to show that DMs can be used as an alternative toMBRs. Especially, when taking into account the results of the reformation rate of 30 mu m DM (6.09 NTU/h) and other high filterability features.