which data are presented appear to have continuing capacity to capture Zn at the end of the
experiments, despite already being subjected to substantial loadings of dissolved metals.
Small columns of crushed shell material remained efficient at removing dissolved metals at
flow velocity of around 10 cm hr
-1
and a solution:solid contact time of 30 minutes (Macaskill
2008). Higher flow rates are likely to be required for the treatment of urban stormwater, so
the efficacy of crushed shell material at higher flow velocities needs to be determined through
further research.