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Nanomaterial Removal and Transformation During Biological Wastewater Treatment
Link to Journal Abstract
Engineered nanomaterials (ENMs) already occur in sewage and wastewater biosolids due to their release from commercial products (e.g., nanoscale titanium dioxide). Increasing levels and diversity of nanomaterials may enter sewage and wastewater treatment plants (WWTPs) in the future as they are released from products containing nanomaterials (e.g., coatings) embedded in products, or from industrial processes that use nanomaterials (e.g., polishing). Some metallic nanomaterials may dissolve (e.g., silver-, zinc-, or copper-based) or biodegrade (e.g., fullerenes) in wastewater, and subsequently sorb to settable biomass, precipitate as inorganic solids, or form stable aqueous complexes. Nanomaterials themselves sorb onto bacterial biomass in WWTPs, leading to their removal from water, but accumulation in biosolids that are disposed to land surface spreading fields, landfills, or incineration where their fate needs to be further considered. Because of the dense biological communities in WWTP unit processes, under typical conditions, >90% of the nanomaterials may attach to biomass, which is removed within the WWTP. Inclusion of membrane filtration to augment gravity settling has the potential to increase nanoparticle removals. At expected production/use levels, the presence of nanomaterials in biomass appears unlikely to influence current biosolids treatment processes (e.g., anaerobic digestion) or landfill biogas production. Additional research is needed to be able to monitor the transformation and removal of nanomaterials throughout WWTPs and biosolids treatment to assure they are not released into the environment where they may pose human or ecological risks.
This paper summarizes concepts of how engineered nanomaterials might be processed in sewage and wastewater biosolids due to their release from commercial products and also calls for additional research to monitor the transformation and removal of nanomaterials throughout WWTPs and biosolids treatment to assure they are not released into the environment where they may pose human or ecological risks.
Exposure Or Hazard Target
Method Of Study
Material Analysis and Applications
Environmental Fate and Transport
Risk Exposure Group
Environmental Engineering Science, 30(3): 109-117 (March 2013)
Environmental Engineering Science
Westerhoff PK, Kiser A, Hristovski K
Last updated on March 21, 2013
This work is supported in part by the Nanoscale Science and Engineering Initiative of the National Science Foundation
under NSF Award Number EEC-0118007.
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