Identification and Quantification of Inorganic Nanoparticles in Wastewater

Chen, Yinduo

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Identification and Quantification of Inorganic Nanoparticles in Wastewater

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Increasing use of inorganic nanoparticles (INPs) in consumer products and industrial processes has resulted in a more significant presence of these nanoparticles in wastewater. It is essential to understand the occurrence and characteristics of various nanoparticles in community wastewater. The primary objectives of this research were (1) to further develop and improve techniques to identify, quantify, and characterize these inorganic nanoparticles; (2) to investigate the presence of nanoparticles from 14 elements in wastewater from a large community with diverse wastewater sources; and (3) to explore the impacts of the size and wastewater sources of wastewater treatment plants (WWTPs) on the occurrence of inorganic nanoparticles. These objectives were motivated by the lack of information on the fate and transport of inorganic nanoparticles in wastewater streams and in the environment after consumer and industrial use. The presence of these nanoparticles in various water sources could pose a potential risk to public health and the environment. Extraction and concentration protocols were developed to prepare samples for instrumental analysis. Single Particle Inductively Coupled Plasma Mass Spectrometry (spICP-MS) was utilized, along with other nanoparticle characterization techniques. Specific accomplishments of this research were: (1) the detection of inorganic nanoparticles from the 14 different targeted elements (Mg, Al, Mn, Fe, Cu, Sr, Mo, Ag, Sn, Ba, Pb, Zr, Ti, Zn) in municipal wastewater at different concentrations in influent and effluent streams; (2) the sizes and concentrations of these inorganic nanoparticles were variable over time due to the complexity of wastewater sources and the sampling period; and (3) the preparatory method developed in this work achieved good removal efficiencies of dissolved materials to minimize matrix-effects in single-particle ICP-MS analysis; (4) the nanoparticle size ranges obtained from different analytical techniques showed significant differences due to size distribution limits and agglomeration; (5) spICP-MS analysis coupled with statistical analysis indicated various levels of differences in nanoparticle concentrations between the WWTPs with different sizes and wastewater sources; (6) the effects of WWTP size (i.e., flowrate) and wastewater sources on detection of inorganic nanoparticles; and (7) the INPs removal efficiencies (10% -100%) between the influent and effluent vary with WWTPs sizes, sources and treatment. This work provides (1) a protocol to collect wastewater samples & analyze various INPs in complex wastewater systems; (2) a framework to assess some major factors affecting the nature of nanoparticles which are of importance to those determining environmental impacts; and (3) valuable information on the concentrations and size of different INPs in wastewater for realistic risk assessment.

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