A long-channel membrane test cell (LCMTC) with the same length as full-scale elements was developed to simulate performance and fouling in nanofiltration and reverse osmosis spiral-wound membrane modules (SWMs). The transparent LCMTC enabled simultaneous monitoring of SWM performance indicators: feed channel pressure drop, permeate flux and salt passage. Both permeate flux and salt passage were monitored over five sections of the test cell and were related to the amount and composition of the accumulated foulant in these five sections, illustrating the unique features of the test cell. Validation experiments at various feed pressures showed the same flow profile and the same hydraulic behaviour as SWMs used in practice, confirming the representativeness and suitability of the test cell to study SWM operation and fouling. The importance to apply feed spacers matching the flow channel height in test cell systems was demonstrated. Biofouling studies showed that the dosage of a biodegradable substrate to the feed of the LCMTC accelerated the gradual decrease of membrane performance and the accumulation of biomass on the spacer and membrane sheets. The strongest permeate flux decline and the largest amount of accumulated biomass was found in the first 18 cm of the test cell. The LCMTC showed to be suitable to study the impact of biofilm development and biofouling control strategies under representative conditions for full-scale membrane elements.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors thank the German Federal Ministry of Education and Research (BMBF) for the financial support of the project “Fouling minimized reclamation of secondary effluents with Reverse Osmosis” (ReSeRO) under grant no. 02WA1076. Further, several people have given time and efforts on discussion of the introduced topic and are thus thanked Mr. A. Lerch (Chair of Water Supply Engineering, TU Dresden, Germany) for stimulating suggestions during the construction of the LCMTC, Mrs. J. Brückner, Mr. G. Orzechowski and Mr. D. Diersche (Chair of Water Supply Engineering, TU Dresden, Germany) for their help regarding analysis and support on the setup of the test rig, respectively, Mr. D. Kreutzmann and Mr. M. Meinel for discussions on material strength and tensions, Mr. J. Friedrich (Institute of Lightweight Engineering and Polymer Technology, TU Dresden) for the supply of the PMMA model calculation on material strength and Mr. S. Bucs (KAUST) for his help with the Rhodamine B experiment.