RESUMEN
Intensification of pollution loading worldwide has promoted an escalation of different types of disease-causing microorganisms, such as harmful algal blooms (HABs), instigating detrimental impacts on the quality of receiving surface waters. Formation of unwanted disinfection by-products (DBPs) resulting from conventional disinfection technologies reveals the need for the development of new sustainable alternatives. Quaternary Ammonium Compounds (QACs) are cationic surfactants widely known for their effective biocidal properties at the ppm level. In this study, a novel silica-based antimicrobial nanofilm was developed using a composite of silica-modified QAC (Fixed-Quat) and applied to a fiberglass mesh as an active surface via sol-gel technique. The synthesized Fixed-Quat nanocoating was found to be effective against E. coli with an inactivation rate of 1.3â¯×â¯10-3 log reduction/cmâ¯min. The Fixed-Quat coated fiberglass mesh also demonstrated successful control of Microcystis aeruginosa with more than 99% inactivation after 10â¯hr of exposure. The developed antimicrobial mesh was also evaluated with wild-type microalgal species collected in a water body experiencing HABs, obtaining a 97% removal efficiency. Overall, the silica-functionalized Fixed-Quat nanocoating showed promising antimicrobial properties for water disinfection and HABs control, while decreasing concerns related to DBPs formation and the possible release of toxic nanomaterials into the environment.
Asunto(s)
Desinfección/métodos , Floraciones de Algas Nocivas , Nanoestructuras/química , Compuestos de Amonio Cuaternario/química , Purificación del Agua/métodos , Vidrio/química , Dióxido de Silicio/química , Contaminación del Agua/estadística & datos numéricosRESUMEN
Clay dispersal is one of only a few mitigation methods for harmful algal blooms (HABs) ever applied in the field; however, low flocculation efficiency has always been the most significant drawback associated with natural unmodified clays. This review discusses key factors affecting the flocculation efficiency, based on results obtained in studies of the mechanisms underlying interactions between clay particles and HAB organisms. It further elaborates clay surface modification theory and methods for improving removal efficiency of HAB cells, followed by descriptions of various modified clays successfully prepared with removal efficiencies of HAB cells that are up to hundreds of times greater than natural clays and have lower dosing requirements of 4-10t/km2. Presently, modified clays are the most widely used method for the mitigation of HAB in the field in China. This review also evaluates potential ecological effects of modified clay disposal on water quality, typical aquatic organisms, benthic environments, and ecosystems. Both laboratory and field results have demonstrated that modified clays markedly can actually improve water quality after treatment and pose no negative effects on aquatic ecosystems.