Data obtained by the above-mentioned tests suggested that the
contact time between wastewater and the
filter-feeding bivalves
was probably one of the most crucial parameters, affecting the
extent of ME removal from wastewater. As previously mentioned,
although the increase of contact time could be almost impossible
at full scale, we decided to carry out tests 24 h long. On the basis of
the results obtained at 4 h, the 24 h tests were performed only on
25% inlet/75% outlet and 50% inlet/50% outlet mixtures. For most of
the MEs, the removal due to mussel
filtration was about 70% with
the 25% inlet/75% outlet mixture