Faculty of Environmental Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
Department of Water and Sewage, Municipal Services of Ladek Zdroj, ul. Fabryczna 7a, 57-540 Ladek Zdroj, Poland
The performance of micellar-enhanced ultrafiltration (MEUF) in removing nutrients from aqueous solutions was evaluated. The process was performed with the use of polyethersulfone (PES) and regenerated cellulose (RC) membranes that varied in terms of molecular weight cut-off values (4÷50 kDa). Nitrate and phosphate solutions containing 28 mg N-NO3-/dm3 and/or 15 mg P-PO43-/dm3 were used in the tests. Cetyltrimethylammonium bromide (CTAB) was chosen as a surfactant to create cationic micelles in the tested solutions. The concentration of CTAB surfactant amounted to 2 and 3CMC (CMC - critical micelle concentration). The results of the study showed that the composition of the solution, membrane material, and membrane molecular weight cut-off influenced the efficiency of the process. The removal of nitrate and phosphate from single-component solutions was approximately 74÷93% and 15÷55%, respectively. The simultaneous removal of nutrients using MEUF revealed a deterioration in phosphate ion rejection - even by 50% when compared to the separation efficiency for single-component solutions. The worsening in nitrate rejection was seen to be insignificant. The adverse effect of nitrate ions on the phosphate ion removal was due to the greater affinity of the nitrate ions than phosphate ions towards CTAB micelles. Secondary contamination of the permeate by CTAB was also observed. The percentage of CTAB passing from the feed to the permeate ranged from 12.9 to 36.2%. The PES and RC membrane vulnerability to fouling varied to a great extent – the relative flux fluctuated from 0.16 to 0.95.