The beneficial use of DWTRs faces barriers due to uncertainties and concerns about their potential environmental impacts. To assess how these waste materials can be repurposed to limit the mobility of metals in aquatic systems, we tested their propensity to release toxic metals (Ag, As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn) and to adversely impact freshwater (Chironomus tentans and Hyalella azteca) and marine (Americamysis bahia and Neanthes arenaceodentata) benthic organisms. To do so, three DWTR samples that met sediment quality guidelines (SQG) based on total metal contents were used. Elutriate studies were conducted using synthetic fresh- and salt-waters and leached total dissolved (0.45um) metals analyzed by ICP-MS. Overall, all measured total metal concentrations were below the USEPA’s criterion maximum concentration (CMC), except for copper (Cu) in salt water elutriates. Cu concentrations measured in the DWTR extracts ranged from about 8.0 to 16 mg/L, which were higher than the CMC (4.8 ppb) and CCC (3.1 ppb), respectively. This can be addressed by dilution to meet the guidelines. Exposure studies using control sediments and DWTR samples as substrates, no toxicity was recorded based on the 10 day A. bahia and the 28 day N. arenaceodentata, with survival rates and growth as endpoints. For freshwater organisms, the long-term 65 day life cycle C. tentans test was used with four endpoints (survival, adult emergence, egg case production, and the number of eggs produced by female), and no statistical differences were found between the DWTR-treatments and the controls. Similarly, results obtained using the 10-day H. azteca test showed no toxicity. However, results from the 10-day C. tentans and the 28-day H. azteca tests were not clear-cut. Overall, our results suggest that certain DWTRs can be suitable for introduction to aquatic systems, if screened adequately.

Total and leacheable concentrations of toxic metals in drinking water treatment residuals (DWTRs) and toxicity implications in marine and freshwater systems

ACS Spring Meeting 2021

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