Evaluating nanoparticle breakthrough during drinking water treatment.
BACKGROUND
Use of engineered nanoparticles (NPs) in consumer products is resulting in NPs in drinking water sources. Subsequent NP breakthrough into treated drinking water is a potential exposure route and human health threat.


OBJECTIVE
In this study we investigated the breakthrough of common NPs--silver (Ag), titanium dioxide (TiO2), and zinc oxide (ZnO)--into finished drinking water following conventional and advanced treatment.


METHODS
NPs were spiked into five experimental waters: groundwater, surface water, synthetic freshwater, synthetic freshwater containing natural organic matter, and tertiary wastewater effluent. Bench-scale coagulation/flocculation/sedimentation simulated conventional treatment, and microfiltration (MF) and ultrafiltration (UF) simulated advanced treatment. We monitored breakthrough of NPs into treated water by turbidity removal and inductively coupled plasma-mass spectrometry (ICP-MS).


RESULTS
Conventional treatment resulted in 2-20%, 3-8%, and 48-99% of Ag, TiO2, and ZnO NPs, respectively, or their dissolved ions remaining in finished water. Breakthrough following MF was 1-45% for Ag, 0-44% for TiO2, and 36-83% for ZnO. With UF, NP breakthrough was 0-2%, 0-4%, and 2-96% for Ag, TiO2, and ZnO, respectively. Variability was dependent on NP stability, with less breakthrough of aggregated NPs compared with stable NPs and dissolved NP ions.


CONCLUSIONS
Although a majority of aggregated or stable NPs were removed by simulated conventional and advanced treatment, NP metals were detectable in finished water. As environmental NP concentrations increase, we need to consider NPs as emerging drinking water contaminants and determine appropriate drinking water treatment processes to fully remove NPs in order to reduce their potential harmful health outcomes.
Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
Talia E
TE
Abbott Chalew
Gaurav S
GS
Ajmani
Haiou
H
Huang
Kellogg J
KJ
Schwab
D060766:Drinking Water / Q000032:analysis*; D053768:Metal Nanoparticles / Q000032:analysis*; D012834:Silver / Q000032:analysis; D014025:Titanium / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000592:standards*; D015034:Zinc Oxide / Q000032:analysis
D060766:Drinking Water; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D015034:Zinc Oxide