Prospects of membrane bioreactors in water supply: Fid-Bau Portal

Prospects of membrane bioreactors in water supply

Glastra, M. / Dijk, H. van / Verberk, J.

Following the introduction of MBRs in the industrial and wastewater treatment, similar advantages of this technique (high quality of the effluent, small footprint, combination of different treatment steps in one MBR) could be discovered in the production of drinking water as well. However, in the MBR concepts found of drinking water production, the bioreactor is not strictly defined; often it is better to speak of membrane reactors. Several possible MBR combinations are suggested in this paper. One example is the removal of nitrate in an membrane bioreactor. The configuration can consist of reverse osmosis in combination with a bioreactor for the biological processing of concentrate. If applicable, the reverse osmosis step will also remove other constituents as hardness. Another possibility is the configuration of an anaerobic bioreactor for biological denitrification followed by ultrafiltration. A second MBR option may be the removal of pesticides in the configurations nanofiltration + bioreactor or bioreactor + ultrafiltration in combination with powered activated carbon. A pilot study into the denitrification of ground water with an MBR showed positive results. The biological process reduced the amount of nitrate as expected. The research mainly focused on optimising the membrane flux by minimising fouling of the membranes. Results show that the crossflow velocity barely influences the final flux. Energetically this means it is best to perform the filtration with a low crossflow velocity. In addition the cake layer which accumulates during a low crossflow velocity can be removed easily by backflush, due to the high porosity of the layer. A model was developed which confirmed these empirical conclusions.