Antimicrobial Ceramic Filters for Water Bio-Decontamination

Olga Ferreira,João Gomes,Sílvia Monteiro,Filipe J Mergulhão,Marisa Gomes,Ricardo Santos,Maria Luísa Serralheiro,Luciana C Gomes,Rita Guedes,Patrícia Rijo,Elisabete R Silva

doi:10.3390/coatings11030323

Abstract

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.

Highlights

IntroductionBallast waters from ships constitute a representative and increasing concern of water use
The Econea biocide was successfully functionalized with 4,40 -methylene diphenyl diisocyanate (MDI) (Supplementary Figure S1) and its structure were confirmed by FTIRATR and Nuclear Magnetic Resonance (NMR), as reported in previous publications [23,24,35], with conversions as high as 95% ± 5% and a free isocyanate content average in the isocyanate-functional Econea derivative (EM) of 9 ± 2 wt.%
The methicillin-resistant Staphylococcus aureus (MRSA) growth could be visually identified by a yellowish, opaque surface on the Tryptic Soy Agar (TSA) medium, and the biocides that were in direct contact with the medium covered with bacteria could be identified as a dispersed powder (Supplementary Figure S2)

Summary

Introduction

Ballast waters from ships constitute a representative and increasing concern of water use Those waters, stored in ships and often released in harbors, can, in the absence of any treatment, contaminate the surface waters by transferring microorganisms from one part of the world to another [4]. The presence of microorganisms and their interaction with those waterborne systems, namely the production of biofilms, can lead to serious economic penalties and health threats, which is enhanced by the current lack of control on their discharge, reinforced by the continuous increase at a global scale, of the shipping transport traffic, including transport in lakes and rivers, which is estimated to transfer about three to five billion tonnes of ballast water per year [5,6]

Methods

Results

Conclusion