Antibiofilm effect enhanced by modification of 1,2,3-triazole and palladium nanoparticles on polysulfone membranes

Abstract

Biofouling impedes the performance of membrane bioreactors. In this study, we investigated the antifouling effects of polysulfone membranes that were modified by 1,2,3-triazole and palladium (Pd) nanoparticles. The modified membranes were evaluated for antibacterial and antifouling efficacy in a monoculture species biofilm (i.e., drip flow biofilm reactor, DFR) and mixed species biofilm experiment (i.e., aerobic membrane reactor, AeMBR). 1,2,3-triazole and Pd nanoparticles inhibited growth of Pseudomonas aeruginosa in both aerobic and anaerobic conditions. The decrease in bacterial growth was observed along with a decrease in the amount of total polysaccharide within the monoculture species biofilm matrix. When the modified membranes were connected to AeMBR, the increase in transmembrane pressure was lower than that of the non-modified membranes. This was accompanied by a decrease in protein and polysaccharide concentrations within the mixed species biofilm matrix. Biomass amount in the biofilm layer was also lower in the presence of modified membranes, and there was no detrimental effect on the performance of the reactor as evaluated from the nutrient removal rates. 16S rRNA analysis further attributed the delay in membrane fouling to the decrease in relative abundance of selected bacterial groups. These observations collectively point to a lower fouling occurrence achieved by the modified membranes.Membrane bioreactors (MBR) are increasingly used as a preferred biotechnology for wastewater treatment because the coupling of a membrane separation process would achieve an improved effluent quality. Membranes can also be used to retain catalytic metals (e.g. manganese oxide, palladium) within the bioreactors. The catalytic metals in turn achieve reductive hydrodehalogenation of contaminants (e.g. pharmaceutical and personal care products, biocides and organic micropollutants) that are otherwise not easily biodegraded in a conventional activated sludge process. To demonstrate, palladium (Pd) has been used as a catalytic metal to achieve reductive removal of pharmaceuticals, biocides and iodinated contrast media 1 . Similarly, Pd was used in a continuous plate membrane reactor to achieve a complete, efficient and rapid removal of trichloroethene (TCE) 2 . In both instances, Pd was either physically retained in the MBR through the use of hollow-fiber nanofiltration membranes or recirculated throughout the reactor system in the form of suspension. However, the lack of a support material for these nanoparticles can result in the agglomeration and growth of nanoparticles, which will cause a subsequent decrease in the catalytic effect 3,4 . Alternatively, Pd particles can be embedded onto membrane surfaces so as to achieve an even distribution of this catalyst throughout the reactive surface area. For example, Hennebel and coworkers encapsulated Pd particles in polyvinylidene fluoride membranes and demonstrated that such modified membrane contactors can be used

An Up-To-Date Review on Biomedical Applications of Palladium Nanoparticles

“…The antibacterial property of PdNPs was recently discovered and the reported data showed that PdNPs have a high potential for antimicrobial applications [31,33,46,47,[78][79][80]. As illustrated in Figure 1, the antibacterial mechanism of PdNPs included both physical and chemical modes.…”

UV and bacteriophages as a chemical-free approach for cleaning membranes from anaerobic bioreactors

“…For EPS analysis, both polysaccharides and proteins concentration were measured as described in a previous study (50). Firstly, 2 mL of biofilm suspension was filtered through 0.22 µm syringe filter to quantify only the filtrate (i.e., dissolved constituents).…”

Understanding the antifouling mechanisms related to copper oxide and zinc oxide nanoparticles in anaerobic membrane bioreactors

“…The membranes were harvested using similar protocols detailed in an earlier study. 9 The sludge in the reactor was sampled weekly for analyses. The COD in the effluent was quantified weekly.…”

“…Examples of antifouling strategies include physical disruption of biofilm matrices using backwash, chemical wash or sonication, 8 chemical modification of membranes (e.g. coating with nanoparticles and modifying membranes with organic functional groups) 9 and biocidal control (e.g. quorum quenching and phage-based decomposition).…”