Title : Modification of PES membrane through in-situ formed silver nanoparticles to mitigate biofouling
Significant failure of membrane processes in wastewater treatment is biofouling. By modifying the membranes with silver nanoparticles, their antimicrobial and hydrophilic properties can be enhanced to increase the efficiency of the membrane process, i.e. the filter cycle will be extended without a frequent application of chemical or mechanical cleaning.
Polymer PES (polyethersulfone) was chosen as the most suitable material for modification and subsequent testing. PES is characterized by a suitable mechanical, chemical and thermal stability and it is capable of binding silver nanoparticles in its structure effectively. The commercial product of the membrane module MS® SUF-4040 from hollow fibers (PES) was modified by the incorporation of silver nanoparticles into the surface structure of the membrane by the diffusion-thermal method. The membrane was flushed with AgNO3 solution (3.5% wt.), where the silver ions were captured in the PES polymer matrix and then reduced with ascorbic acid to the elemental silver particles. Nanoparticles are mainly bonded by mechanical bonding, which ensures that they remain in the polymer matrix during the filtration process.
Testing of the modified membrane at the pilot scale was carried out using a filtering apparatus (from Mega a.s., Czech Republic). The primary input and output parameters of the process (pressure, flow, temperature) were continuously measured with the installed sensors. Modified and reference membranes were tested for a given time with wastewater from the settling tank after sand filtration. The biofouling reduction efficiency for the reference and the modified membrane was compared on the basis of pressure, flow and other parameters (point sampling chemical analysis).
The synergistic effects of the antimicrobial properties of silver nanoparticles and the increased surface hydrophilicity reduce the interaction of microorganism and other biological materials which interact with the surface. 30% higher production of permeate (with equal or higher purity) was recorded in the modified membrane as compared to the reference membrane. The modified membrane showed antimicrobial properties and biofouling reduction.
Audience take away:
• PES membranes modified through silver nanoparticles and influence for biofouling
• Methods of testing and evaluation of the membrane process
• Determination of antimicrobial properties, permittivity and efficiency of modified membrane
• The modified membrane exhibits better filtration efficiency than the reference membrane
• Other options for modifying the membranes