In addition, the significant increase (varied from 20% to 140%) of
ash content in the hyacinth straw treated with wastewater was another
adsorption characteristic of this plant material (Table 4).
3.3. Phosphorus adsorption experiment in laboratory
Fig. 3 includes the data obtained from the phosphorus adsorption
experiment carried out in the laboratory. In the control group,
phosphorus concentration in the solution increased steadily and
was about 19% higher by the end of than in the beginning of the
test. Meanwhile, the liquid volume reduced from an initial 2.5 L
to an average of 2.1 L in the end. The phosphorus content in the
solution varied between 43.83 ± 0.05 and 43.81 ± 0.23 mg, showing
no substantial difference throughout the experiment.
On the contrary, TP in the treatment group solutions dropped
about 12% upon the second sampling (the 3rd day), implying that
more than 19% of the applied phosphorus were removed from
the liquid in less than 48 h. The reduction of TP slowed down afterwards,
and stopped after the sixth sampling, i.e., the 11th day of
the experiment. The final TP remaining in the solution was
14.91 mg L1
. This meant that the adsorption of TP by the hyacinth
material had approached saturation when the removal rate
reached 36% and the adsorption capacity was about 0.32 mg TP/g
straw.