5. The reduction of T-P (mg/l) and T-N (mg/l) by microorganisms
on the 7th and 11th days of the water
purification test may be due to the fact that the T-P and
T-N removal capacity of the microbes has reached their
limits in the confined space, or the fact that the activity of
the bio-film attached to the porous concrete surface
became less active after consuming the majority of the
dissolved oxygen in the test water. If the porous concrete
can maintain the DO (mg/l) concentration at a level
equivalent to that of natural rivers, it can be effectively
used for the continuous purification of water.