Fate of Nanoparticles in Municipal Solid Waste Landfills
Investigators: University of Central Florida
Project Background & Objectives
Over the last decade engineered particles with nanoscale dimensions have been key to advancements in drug delivery and pharmaceuticals, cosmetics, environmental remediation, nanotechnology, biomaterials, and energy production (Bhatt and Tripathi, 2011; Musee, 2011; Colvin 2003; Turco et al. 2008; Bittnar, Bartos et al. 2009; Sattler, 2011; Dreher 2004). Nanoparticles (NPs) are classified as having all three dimensions less than 100 nm (British Standards 2007; Linkov and Steevens, 2009; Sattler, 2011), whereas nanomaterials (NMs) have at least one dimension between 1 nm and 100 nm (Roco, 2003). NMs are commonly used because of their large surface area (Vollath, 2008) and unique electronic, optoelectronic, thermal, and catalytic properties (Linkov and Steevens, 2009). These unique properties can be attributed to the alteration of both chemical and physical properties as size is reduced (Farré et al., 2009). Most of the NPs that are incorporated into consumer products are coated, surface modified, and/or functionalized to achieve specific properties (Reinhart et al., 2010). According to an inventory completed by the Project on Emerging Nanotechnologies (Nanotech-Project, 2011), 1,317 consumer products containing NPs were available in 2010. Of these products, just over 55% were health and fitness related and also included electronic components, cosmetics, antibacterial agents, polishing and binding agents, solar cells and UV-absorbers in sunscreen lotion, among many others (Linkov and Steevens, 2009).
It has been estimated that the manufacturing of NPs will increase from 1,000 to 58,000 tonnes yearly from 2011 to 2020 (Royal Society and Royal Academy of Engineering, 2004). As NPs continue to be incorporated into consumer products, the introduction of these materials to landfills and the environment is inevitable. To fully understand the environmental implications of NPs use, knowledge regarding their mobility, bioavailability, and ecotoxicity is important (Farré et al., 2009).
Given the increase in NP use and the large fraction of waste placed in landfills worldwide, the probability of these products reaching municipal solid waste (MSW) landfills at the end of their useful life is high. Since nanotechnology is still in its early stages, there are currently few regulations pertaining to the disposal of NPs and there is limited information regarding the fate in MSW landfills is still unknown. Therefore, there is a need to study the fate and transport of NPs within waste environments and determine whether these products can potentially affect the environment.
This research sought to understand the fate of NPs within landfills by examining the interactions between NPs and landfill leachate components. The primary focus of this study was to evaluate the effect of Zinc Oxide (ZnO), Titanium Dioxide (TiO2), and silver NPs (Ag) on biological landfill processes, solids characterization, and chemical speciation of Zinc (Zn), Titanium (Ti), and Silver (Ag) in landfill leachate following the addition of crystalline, nano-sized ZnO, TiO2, and Ag. This research (1) observed the effects of coated NPs on leachate five-day biochemical oxygen demand (BOD5) and biochemical methane potential (BMP), (2) examined effects of solids aggregation on the fate of NPs, (3) characterized the NPs before and after addition to leachates, (4) quantified the concentration of metals associated with the added NPs by size fractions, and (5) modeled the chemical speciation of Zn, Ti, and Ag in landfill leachate using Visual MINTEQ. The NPs studied were chosen for their common use in personal care products which accounted for just over 55% of the inventory of NP-containing consumer products available in 2010 (Nanotech-Project, 2011).
Behavior of Engineered Nanoparticles in Landfill Leachate, Stephanie C. Bolyard, Debra R. Reinhart, and Swadeshmukul Santra, Environmental Science & Technology 2013 47 (15), 8114-8122