Fouling reduction in membrane reactor through magnetic particles

Magnetic particles were explored as means to prevent membrane fouling. Porous micro-sized magnetite (Fe3O4) powder was prepared via the simple co-precipitation method. It did not demonstrate significant adsorption of alginate at ambient temperature and pH, but was able to achieve a maximum adsorption of 5.18 mg/g for bovine serum albumin (BSA) as per the Langmuir adsorption model. The electrostatic repulsion between magnetite and BSA molecules and the small pore size of the particles probably restricted adsorption capacity. Despite this, the addition of magnetite to a laboratory-scale reactor successfully inhibited the protein-induced fouling of commercial poly(vinylidene fluoride) PVDF membrane. Its effectiveness was dependent on liquid shear intensity from mechanical mixing: at low stirring rates magnetite increased membrane output and permeability, whereas at higher rates it was counterproductive. Stirring at 60 rpm yielded the greatest fouling mitigation effect. Furthermore, magnetite improved the performance of the membrane during batch filtration of aerobic sludge, validating its potential as foulant reducer.

► Magnetite made by co-precipitation separates BSA from solution, but not alginate.
► It retards BSA-induced fouling of PVDF membrane at mild shear intensity.
► It worsens fouling if shear intensity is too high.
► It also improves the performance of membranes filtering real sludge.