In practice, trace metals are often supplemented in excessive
amounts, which can lead to inhibitory effects on the biological treatment
processes. This is due to the lack of an in-depth understanding
of trace metal speciation and bioavailability. Initially, the bioavailability
of trace metals was generally quantified based on the total rather than
‘free’ or bioavailable metal concentrations. However, it is now clear
that chemical speciation is critical when predicting bioavailability.
Although trace metal speciation has been studied extensively over the
years to determine the fate of trace metals in an anaerobic environment,
its relationship with trace metal bioavailability is still not clearly
understood.