Natural aging of expanded shale, clay, and slate (ESCS) amendment with heavy metals in stormwater increases its antibacterial properties: Implications on biofilter design.

Aging is often expected to decrease the pathogen removal capacity of media because of exhaustion of attachment sites by adsorption of co-contaminants and dissolved organics. In contrast, the adsorption of metals naturally present in stormwater during aging could have a positive impact on pathogen removal. To examine the effect of adsorbed metals on pathogen removal, biofilter media amended with expanded clay, shale, and slate (ESCS) aggregates, a lightweight aggregate, were exposed to metals by intermittently injecting natural stormwater spiked with Cu, Pb, and Zn, and the capacity of aged and unaged media to remove Escherichia coli (E.