In rivers, however, it is necessary to block the abundant
flowing populations of water hyacinth, although it
may imply the use of large labour and materials use at
high cost. In the case of plenty water hyacinth saved
from water, it is very important to treat the weed in
time in order to avoid second pollution to the envi-
ronment caused by the dead and decay of the weed.
We can use water hyacinth to produce organic fertil-
izer (Chu, 2004b)