New Functionalized Macroparticles for Environmentally Sustainable Biofilm Control in Water Systems

Abstract

Reverse osmosis (RO) depends on biocidal agents to control the operating costs associated to biofouling, although this implies the discharge of undesired chemicals into the aquatic environment. Therefore, a system providing pre-treated water free of biocides arises as an interesting solution to minimize the discharge of chemicals while enhancing RO filtration performance by inactivating bacteria that could form biofilms on the membrane system. This work proposes a pretreatment approach based on the immobilization of an industrially used antimicrobial agent (benzalkonium chloride—BAC) into millimetric aluminum oxide particles with prior surface activation with DA—dopamine. The antimicrobial efficacy of the functionalized particles was assessed against Escherichia coli planktonic cells through culturability and cell membrane integrity analysis. The results showed total inactivation of bacterial cells within five min for the highest particle concentration and 100% of cell membrane damage after 15 min for all concentrations. When reusing the same particles, a higher contact time was needed to reach the total inactivation, possibly due to partial blocking of immobilized biocide by dead bacteria adhering to the particles and to the residual leaching of biocide. The overall results support the use of Al2O3-DA-BAC particles as antimicrobial agents for sustainable biocidal applications in continuous water treatment systems.

A Multi-Purpose Approach to the Mechanisms of Action of Two Biocides (Benzalkonium Chloride and Dibromonitrilopropionamide): Discussion of Pseudomonas fluorescens’ Viability and Death

“…It is important to note that the PI uptake percentages observed for C − (18-21%) are consistent with data reported in the literature (Fernandes et al, 2020;Barros et al, 2021). The question why live cells can be stained with PI remains unanswered (Shi et al, 2007).…”

“…The LIVE/DEAD ® Baclight™ kit (Invitrogen) was used to assess membrane integrity of bacterial cells after exposure to biocides. In brief, an aliquot of 1 mL was filtered through a 0.2-μm Nucleopore ® (Whatman) black polycarbonate membrane and stained with 250 μl of SYTO9™ and 50 μl of propidium iodide (PI) in the dark (Barros et al, 2021). After reacting for 7 min, the stains were filtered and the samples mounted on a slide with immersion oil.…”

New Insights on Biofilm Antimicrobial Strategies, 2nd Volume

“…However, when reusing the Al 2 O 3 -DA-BAC particles, a higher contact time was needed to reach total inactivation. The authors concluded that Al 2 O 3 -DA-BAC particles are a suitable antimicrobial agent for the treatment of continuous water systems with minimal environmental and health impacts [ 7 ].…”