The highest enhancement factor Q was obtained at the rZVI/VSS of
2.63 and the highest q-value occurred at the rZVI/VSS of 0.74 among
the tested combined systems (see Table 1 in Supplementary material),
which indicating that appropriate increase of ZVI dosing could
improve the synergies of microorganism and ZVI, but too much ZVI
adding would make the ZVI-facilitated effect weaker and the ZVI
utilization decrease.