Diatoms in wastewater treatment: Potentials, applications, and values of biomass

Diatoms have unique silica cellular and metabolic characteristics and can grow in various environments, including wastewater, facilitating pollutant removal. Diatoms provide a sustainable solution to municipal wastewater treatment, particularly in the tertiary and quaternary stages, contributing to carbon neutrality. Diatom-based materials (such as diatom biomass) have wide applications and can be processed into value-added bioproducts such as lipids, polysaccharides, and pigments. Despite their potentials, the applications of diatoms in wastewater treatment are limited. Existing reviews fail to address how diatom growth kinetics affects wastewater treatment. Here, we for the first time summarize diatom growth kinetics and propose promising species for municipal wastewater treatment. Given the scarcity of reviews on diatom performance in wastewater treatment, we also discuss the efficacy of diatoms in removing contaminants from municipal wastewater. Moreover, we elucidate the removal mechanisms of nutrients, heavy metals, and emerging contaminants by diatoms that are missing in existing reviews. Considering the complexity of wastewater, we emphasize selecting diatom species with high growth rates, tolerance to contaminants, efficient nutrient removal/uptake, and COD removal, and bioproduct yields. This will ensure both effective treatment and economic viability. In addition, we discuss the value of diatom frustules and bioproducts generated from wastewater. Lastly, we highlight future directions including promoting diatom growth, exploring diatom-dominated consortia in wastewater treatment, and evaluating the values of diatom biomass cultivated in wastewater. This review examines the potential and applications of diatoms in municipal wastewater treatment, especially effluent polishing. Diatoms are a sustainable solution to municipal wastewater treatmentDiatoms can remove nutrients, heavy metals, and emerging pollutants from wastewaterSummarized the growth kinetics of various diatom species for the first timeDiscussed the removal mechanisms of contaminants from wastewater by diatomsCompiled the wide applications of diatom biomass from wastewater Diatoms are a sustainable solution to municipal wastewater treatment Diatoms can remove nutrients, heavy metals, and emerging pollutants from wastewater Summarized the growth kinetics of various diatom species for the first time Discussed the removal mechanisms of contaminants from wastewater by diatoms Compiled the wide applications of diatom biomass from wastewater</p

Particulate Respirators Functionalized with Silver Nanoparticles Showed Excellent Real-Time Antimicrobial Effects against Pathogens

Particulate respirators designed to filtrate fine particulate matters usually do not possess antimicrobial functions. The current study aimed to functionalize particulate respirators with silver nanoparticles (nanosilver or AgNPs), which have excellent antimicrobial activities, utilizing a straightforward and effective method. We first enhanced the nanosilver-coating ability of nonwoven fabrics from a particulate respirator through surface modification by sodium oleate. The surfactant treatment significantly improved the fabrics’ water wet preference where the static water contact angles reduced from 122° to 56°. Both macroscopic agar-plate tests and microscopic scanning electron microscope (SEM) characterization revealed that nanosilver functionalized fabrics could effectively inhibit the growth of two model bacterial strains (i.e., <i>Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i>). The coating of silver nanoparticles would not affect the main function of particulate respirators (i.e., filtration of fine air-borne particles). Nanosilver coated particulate respirators with excellent antimicrobial activities can provide real-time protection to people in regions with severe air pollution against air-borne pathogens