Silver nanoparticles for water treatment

The aim of this study was to determine the colloidal interaction between silver nanoparticles (Ag-NPs) and Escherichia coli in water and its effect on coli survival. Physical properties of the particles, such as concentration, shape and size, and of the microorganism, such as concentration and type, were identified as impacting parameters. This study advanced scientific knowledge by presenting a single core parameter that incorporates many of the parameters previously reported to impact the inactivation process and the contribution of particle charge to that activity. The ratio between the number of Ag-NPs and the number of biocolloids (bacteria) (NP/N0) was calculated for each sample. Results showed that similar NP/N0 values result in similar log10 reductions in bacteria, regardless of nanoparticle size or concentration (within a certain range). This study was published in the Journal of Colloid and Interface Science. We further presented the use of Ag-NPs as a strategy to control biofouling in water membrane-filtration systems. These results were published in Water Research and in Desalination and Water Treatment.

 

AOPs for biofouling control

Unwanted microbial deposition, termed “biofouling”, creates a serious operational problem in all water sectors, including surfaces such as water-distribution pipes and membranes used for water desalination. This research, funded by the MAGNET Program, the Ministry of Industry, Trade & Labor, aimed to develop a technological solution to control biofouling. We investigated the UV-based advanced oxidation processes (AOPs), with medium-pressure (MP) UV light and hydrogen peroxide (MP-UV/H2O2) as a pretreatment technology to control biofouling. We first determined the optimal UV wavelengths for biofouling control, and published the results in the highly accredited journal Biofouling. We further found that the treatment combination of H2O2 and UV to generate free radicals (UV-based AOP) has high potential as a biofouling-control strategy with model bacteria. UV irradiation alone could prevent biofilm formation, depending on the UV dose and spectrum, but only for limited periods of time post-treatment due to the absence of a residual H2O2 This work resulted in publications in the journals Biofouling and Water Science and Technology. Finally, we investigated the impact of MP-UV/ H2O2 as a pretreatment technology to control biofouling by indigenous microorganisms on a pilot scale in the Lake Kinneret drinking water-distribution system (WDS) and in saline water. We are in the process of submitting two more papers on the pilot results, and another paper on the impact of UV-based AOP on gene expression for biosensor development.