Fe3+-saturated montmorillonite effectively deactivates bacteria in wastewater

Abstract

• Fe 3+ -saturated montmorillonite's antibacterial activity was studied.• Wastewater bacteria was deactivated effectively by Fe 3+ -saturated montmorillonite.• Fe 3+ -saturated montmorillonite deactivated bacteria possibly by cell membrane damage.• Fe 3+ -saturated montmorillonite can disinfect bacteria-contaminated water. G R A P H I C A L A B S T R A C TThe graphic abstract figure is only for simple demonstration of possible reaction processes. Sizes of different components do not reflect their actual relative scales.a b s t r a c t a r t i c l e i n f o Existing water disinfection practices often produce harmful disinfection byproducts. The antibacterial activity of Fe 3+ -saturated montmorillonite was investigated mechanistically using municipal wastewater effluents. Bacterial deactivation efficiency (bacteria viability loss) was 92 ± 0.64% when a secondary wastewater effluent was mixed with Fe 3+ -saturated montmorillonite for 30 min, and further enhanced to 97 ± 0.61% after 4 h. This deactivation efficiency was similar to that when the same effluent was UV-disinfected before it exited a wastewater treatment plant. Comparing to the secondary wastewater effluent, the bacteria deactivation efficiency was lower when the primary wastewater effluent was exposed to the same dose of Fe 3+ -saturated montmorillonite, reaching 29 ± 18% at 30 min and 76 ± 1.7% at 4 h. Higher than 90% bacterial deactivation efficiency was achieved when the ratio between wastewater bacteria population and weight of Fe 3+ -saturated montmorillonite was at b 2 × 10 3 CFU/mg. Furthermore, 99.6-99.9% of total coliforms, E. coli, and enterococci in a secondary wastewater effluent was deactivated when the water was exposed to Fe 3+ -saturated montmorillonite for 1 h. Bacterial colony count results coupled with the live/dead fluorescent staining assay observation suggested that Fe 3+ -saturated montmorillonite deactivated bacteria in wastewater through two possible stages: electrostatic sorption of bacterial cells to the surfaces of Fe 3+ -saturated montmorillonite, followed by bacterial deactivation due to mineral surface-catalyzed bacterial cell membrane disruption by the surface sorbed Fe 3+ . Freeze-drying the recycled Fe 3+ -saturated montmorillonite after each usage resulted in 82 ± 0.51% bacterial deactivation efficiency Contents lists available at ScienceDirectScience of the Total Environment j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n v even after its fourth consecutive use. This study demonstrated the promising potential of Fe 3+ -saturated montmorillonite to be used in applications from small scale point-of-use drinking water treatment devices to large scale drinking and wastewater treatment facilities.

In Vitro Antimicrobial Activity Of Layered Silicate Materials

“…As it turned out, some of the data presented in the literature indicated the antibacterial effect of iron-containing samples [11,21]. For example, in the study by Qin C., et al, the antibacterial activity of montmorillonite saturated with Fe 3+ was investigated using urban wastewater.…”

“…The bacterial decontamination efficiency (loss of bacterial viability) was 92±0.64% when the secondary wastewater was mixed with Fe 3+ -saturated montmorillonite for 30 minutes and then increased to 97±0.61% after 4 hours. Nearly all (99.9%) E. coli and enterococci in the secondary wastewater were deactivated when the water was exposed to Fe 3+ -saturated montmorillonite for 1 hour [11]. One of possible action mechanisms is the suppression of microbial growth by trivalent iron via the formation of hydroxyl free radicals.…”

“…In connection with the current situation, it is urgent to search for, and approbate, non-antibiotic methods of therapy and prevention of bacterial infections, including the use of natural mineral complexes. Some publications mentioned using the samples of layered silicate complexes as an alternative and/or supplementary method for treating bacterial infectious diseases [11,12]. Bentonite clays constituent valuable mineral-based raw materials.…”

Bactericidal and Virucidal Efficacies and Safety of Puriton®

“…It has several biological efficacies, such as antibacterial effects, anti-viral effects, and detoxification [27]. Qin et al reported that Fe 3+ -saturated montmorillonite could suppress bacterial activity in municipal wastewater effluents [28]. Germanium biotite has been used as a dietary material for preventing porcine reproductive and respiratory syndrome viruses [29].…”

Natural Nano-Minerals (NNMs): Conception, Classification and Their Biomedical Composites

“…Many of these materials are nanomaterials with increased specific surface areas, allowing greater exposure of active sites. NNMs contain antibacterial atoms such as Fe and Cu due to their homogeneous substitution in the environment . In addition, their nanomorphology results in a significant specific surface area, making them effective agents against bacteria both independently and as carriers.…”