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Water Res. 2019 Apr 3;157:454-462. doi: 10.1016/j.watres.2019.03.097. [Epub ahead of print]

Polymer-clay composite geomedia for sorptive removal of trace organic compounds and metals in urban stormwater.

Author information

1
NSF Engineering Research Center for Reinventing the Nation's Urban Water Infrastructure (ReNUWIt), Department of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, CA 94720-1716, USA; Department of Civil & Environmental Engineering, University of Washington, Seattle, WA, 98195, USA.
2
Department of Soil and Water Sciences, The Robert Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, 7610001, Israel; Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14850, USA.
3
NSF Engineering Research Center for Reinventing the Nation's Urban Water Infrastructure (ReNUWIt), Department of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, CA 94720-1716, USA.
4
Department of Soil and Water Sciences, The Robert Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, 7610001, Israel.
5
NSF Engineering Research Center for Reinventing the Nation's Urban Water Infrastructure (ReNUWIt), Department of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, CA 94720-1716, USA. Electronic address: sedlak@berkeley.edu.

Abstract

Functionalized polymer-clay composites were developed and characterized as engineered geomedia for trace contaminant removal during infiltration of urban runoff. Montmorillonite clays were functionalized with either poly(diallyldimethylammonium) chloride (PDADMAC) or poly(4-vinylpyridine-co-styrene) (PVPcoS) to enhance organic compound sorption using a simple, scalable synthesis method. Seven representative trace organic compounds and six trace metals were employed to assess the performance of the polymer-clay composites relative to biochar (i.e., an adsorbent proposed for similar purposes) in batch sorption and column studies under simulated stormwater conditions. Contaminant and geomedia electrostatic and hydrophobic interactions, and the presence of natural organic matter (NOM) affected sorption. In batch studies, polymer-clay composites exhibited similar performance to biochar for perfluoroalkyl substance removal, but had lower affinity for polar pesticides and tris(2-chloroethyl) phosphate. Oxyanion removal was greatest for positively-charged PDADMAC-clay composites (particularly Cr[VI]), while PVPcoS-clay composites removed over 95% of Ni, Cd, and Cu. NOM decreased removal of all organic compounds, but increased trace metal removal on clay composites due to sorption of NOM-complexed metals. Polymer-clay composite-amended columns best removed oxyanions, while biochar-amended columns exhibited superior removal for all trace organics. At 3 wt% geomedia-sand loading, clay composites exhibited significantly higher saturated hydraulic conductivity than biochar, which is advantageous when clogging is a concern or when rapid infiltration is needed. Under typical urban stormwater conditions, the clay composites will remove contaminants for at least 20-30 years before regeneration or replacement is needed.

KEYWORDS:

Biochar; PFAS; Pesticide; Sorption; Urban stormwater

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