Antimicrobial Ceramic Filters for Water Bio-Decontamination

Bio-contamination of water through biofouling, which involves the natural colonization of submerged surfaces by waterborne organisms, is a global socio-economic concern, allied to premature materials bio-corrosion and high human health risks. Most effective strategies release toxic and persistent disinfectant compounds into the aquatic medium, causing environmental problems and leading to more stringent legislation regarding their use. To minimize these side effects, a newly non-biocide-release coating strategy suitable for several polymeric matrices, namely polydimethylsiloxane and polyurethane (PU)-based coatings, was used to generate antimicrobial ceramic filters for water bio-decontamination. The best results, in terms of antimicrobial activity and biocide release, showed an expressed delay and a decrease of up to 66% in the population of methicillin-resistant Staphylococcus aureus bacteria on ceramic filters coated with polyurethane (PU)-based coatings containing grafted Econea biocide, and no evidence of biocide release after being submerged for 45 days in water. Biocidal PU-based surfaces were also less prone to Enterococcus faecalis biofilm formation under flow conditions with an average reduction of 60% after 48 h compared to a pristine PU-based surface. Biocidal coated filters show to be a potential eco-friendly alternative for minimizing the environmental risks associated with biofouling formation in water-based industrial systems.

Millimetric particles functionalized with biocide to improve biofouling control in RO system

<p>Biofouling is responsible for more than 45% of all membrane fouling associated problems and is highly relevant for the performance of Reverse Osmosis systems (RO). Biofouling has a tremendous negative impact on the quality and quantity of permeate water and is responsible for high operational and maintenance costs associated with such systems. Current strategies targeting biofilm control on membrane systems often include the overuse of disinfectants which most of the time fail to effectively prevent biofouling build-up, can lead to the formation of dangerous disinfection by-products and represents high amounts of discharged biocides.</p> <p> </p> <p>The present work aims to study how millimetric (1-3 mm length) alumina particles, functionalized with a well-known quaternary ammonium compound biocide (benzalkonium chloride) and immobilized into a Particle Biocide Bed Reactor can effectively contribute to mitigate biofilm formation in membrane systems. For that, the functionalized particles were chemically characterized, and their antimicrobial activity was assessed in batch and recirculation assays and quantified in terms of Culturability and Propidium Iodide (PI) uptake. Special attention has been given to biocides’s (free and immobilized) mechanism of action and potential biocide release was evaluated by High Performance Liquid Chromatography (HPLC) measurements.</p> <p> </p> <p>The preliminary experiments indicate that the immobilized biocide (equivalent biocide concentration of 3 g/L) has an antimicrobial activity against Pseudomonas fluorescens (initial concentration 10<sup>8</sup> CFU/mL) by reducing 4 logs after 30 min and 8 logs after 1 h. On the other hand, the control assays (functionalized particles in water with no bacteria), also shows a biocide release between 0.8 and 1% to the bulk water after 30 min, both in batch and in the Particle Bed Reactor with recirculation experiments. No significant biocide increase is observed in the bulk liquid studies for two weeks. Nonetheless, some changes in the functionalization approach are being made to improve the biocidal anchoring to the particle.</p>

Development of biomaterial surfaces with and without microbial nanosegments

Infections by microorganisms are a major problem in public health throughout the world. Artificial materials, including biomedical goods, inherently lack defense against microbial development. Therefore, microbial cells can adhere on any type of artificial surface, particularly in a moist environment, and start to multiply to form a huge population. In this review, we will discuss a strategy for designing antimicrobial polymers and antimicrobial surfaces. Generally, there are five types of antimicrobial polymers: (a) polymeric biocides, (b) biocidal polymers, (c) biocide-releasing polymers, (d) bioactive oligopeptides, and (e) antimicrobial surfaces. Antimicrobial surfaces preventing the growth of microorganisms are a promising method to inhibit the spread of microbial infections. The antimicrobial surfaces can reject the attachment of microbes and/or kill microbes in the vicinity and can be designed to kill microbes on contact. It is recommended that the material surface not release biocidal substances, therefore preventing exhaustion of biocide release to kill microbes. Furthermore, the antimicrobial surfaces are desired to be nontoxic to human cells. The development of contact-active antimicrobial surfaces by grafting antimicrobial nanosegments onto the material surface will be an important topic in the future.