Antibiofilm Effect Enhanced By Modification Of 1,2,3 Triazole And Palladium Nanoparticles On Polysulfone Membranes

Membrane bioreactors(MBR) are increasingly used as a preferred biotechnology for wastewater treatment. However, the strategy would be susceptible to biofoulants' deposition over the course of reactor operation. In this study, we proposed six types of membranes modified by 1,2,3-triazole ligands and then chelated with Palladium ions and nanoparticles(i.e. PSU-Tri N-0%, PSU-Tri N-23%, PSU-Tri N-94%, PSU-Tri N-Ions, PSU-Tri N-NPs). These membranes were then tested by a monoculture Drip-flow Biofilm Reactor(DFR) and another mix-culture Aerobic Membrane Biofilm Recator(Ae MBR) about the antifouling effect. This study's aims to demonstrate that a PSU membrane modified with both triazole and Pd nanoparticles would show high antifouling properties, and study the mechanism to delay in membrane fouling would occur for such modified membranes. We hope to offer more information of the possible application of this kind of membranes.The important conclusion from this study:(1)This study proved that Palladium membrane even distributed on the surface of membrane. Compared to other membranes, PSU-Tri N-NPs and PSU-Tri N-Ions showed the highest surface. The Ra parameter from AFM quantification were respectively 56.8 and 56.9 of PSU-Tri N-Ions and PSU-Tri N-NPs. In all the membranes, PSU-Tri N-NPs was the most hydrophilic with a 47.72±1.34° contact angle.(2)The DFR test acted with P. aeruginosa showed that 1,2,3-triazole or Palladium can significantly inhibit the growth of bacteria: The live/dead ratio from the confocal laser scanning microscopy pictures by Image J software were all less than 1 on the 1.2.3-triazole or Palladium modification but not PSU-Tri N-0%. Some result was got for the live cell counting by flowcytometry. For instant, live cells in the biofilm matrix on PSU-Tri N-0% were significantly larger than on other membranes. The EPS quantification indicated 1, 2, 3-triazole or Palladium can decrease the total polysaccharides, and Pel polysaccharides but not the proteins. There were 2.34±0.20 ?g/(m L.cm2) total polysaccharides in aerobic condition and 3.25±0.26 ?g/(m L.cm2) total polysaccharides in anaerobic condition on PSU-Tri N-0% membrane, which was significantly higher than other membranes(t-test, all P<0.05). Further compared PSU-Tri N-94% with PSU-Tri N-Ions and PSU-Tri N-NPs, founding PSU-Tri N-NPs but not PSU-Tri N-Ions can decrease the total polysaccharides. Some result was also obtained about the Pel polysaccharides. Owing the interfere of protein from LB broth, we failed to get the actual content of protein.(3)The Ae MBR test of PSU-Tri N-0% PSU-Tri N-94% and PSU-Tri N-NPs indicated PSU-Tri N-NPs performed best to resist biofilm. PSU-Tri N-NPs showed delayed TMP increment for PSU-Tri N-NPs only had 40 kpa in run 1 and 10 kpa in run 2 at the point of harvesting. The EPS quantification indicated PSU-Tr IN-NPs can decrease both total polysaccharides and proteins. For instance, the total polysaccharides concentration on PSU-Tr IN-NPs membrane were 48.14±10.72 ?g/cm2 in run 1 and 5.86±0.48 ?g/cm2 in run 2, significantly lower than the control membrane(i.e. PSU-Tri N-0%). Furthermore, the protein concentration on PSU-Tri N-NPs was 34.14 ?g/cm2 in run 1 and was significantly lower than other two membranes(i.e. PSU-Tri N-0%, PSU-Tri N-NPs)(t-test, P=0.00 and 0.00 respectively). Similarly, the concentration in run 2 was 4.40 ?g/cm2 and was significantly lower the control membrane(t-test, P=0.00). Additionally, the quantification of ATP and AI-2 proved PSU-Tri N-NPs can inhibit the live cells and quorum sensing single in biofilm matrix.(4)The microbial community structure revealed the mechanism to the antifouling effects of PSU-Tri N-NPs membrane. The PCA analysis showed the microbial community structure was obviously different on PSU-Tri N-NPs and PSU-Tri N-0%(ANOSIM,r R = 0.889 and 0.815 in run 1 and run 2, respectively, P = 0.1). To illustrate, the relative abundance of unclassified Acidobacteria Gp4, which is a predo minant group detected in the biofilm matrix, accounted for 12.4% of total microbial community on PSU-Tri N-NPs in run 1. This relative abundance was 35% lower than that on PSU-Tri N-0%. In run 2, the same unclassified Acidobacteria Gp4 was also 52% lower in relative abundance on PSU-Tri N-NPs than PSU-Tri N-0%. Several OTUs such as Terrimonas lutea,Acinetobacter and Acidovoraxthat which was respectively reported to correlate to bacterial attachmemt, biofilm formation and to the abundance of quorum-sensing signal molecules were identified and can be inhibited by 1,2,3-triazole and Palladium nanoparticles modified membrane PSU-Tri N-NPs.