Table 3.
Seasonal changes in growth rates of duckweed, nutrients removals and chlorophyll concentration in synthetic wastewater
| Months | Days from start | Growth density, g dw/m2 | Growth rate, g dw/m2-day | NH4-N initial, mg/l | NH4-N final, mg/l | NH4-N uptake rate, mg/l-day | PO4-P initial, mg/l | PO4-P final, mg/L | PO4-P uptake rate, mg/l-day | N/P uptake | Chl A + B, μg/ml |
|---|---|---|---|---|---|---|---|---|---|---|---|
|
January |
10 |
NA |
NA |
250.0 |
166.1 ± 18 |
8.4 ± 4 |
30.0 |
20.7 ± 6 |
0.93 ± 0.14 |
9 |
45.7 ± 12 |
| 15 |
NA |
NA |
|
46.2 ± 8 |
13.5 ± 6 |
|
8.9 ± 4 |
1.4 ± 0.9 |
9.6 |
19.3 ± 8 |
|
| 20 |
42.5 ± 10 |
2.1 ± 0.9 |
|
0.0 |
12.5 ± 7 |
|
3.9 ± 2 |
1.3 ± 0.7 |
9.5 |
12.3 ± 6 |
|
|
April |
10 |
NA |
NA |
250.0 |
176.7 ± 29 |
7.3 ± 3 |
30.0 |
20.6 ± 8 |
0.9 ± 0.4 |
7.8 |
15.8 ± 5 |
| 15 |
NA |
NA |
|
77.1 ± 11 |
11.5 ± 3 |
|
12.6 ± 6 |
1.20 ± 0.9 |
9.9 |
7.5 ± 3 |
|
| 20 |
71.1 ± 16 |
3.5 ± 0.9 |
|
37.1 ± 7 |
10.6 ± 4 |
|
10.6 ± 3.0 |
0.9 ± 0.4 |
10.9 |
2.5 ± 1.2 |
|
| June | 10 |
NA |
NA |
250.0 |
221.1 ± 30 |
2.8 ± 2 |
30.0 |
26.9 ± 11 |
0.31 ± 0.2 |
9.3 |
5.8 ± 2 |
| 15 |
NA |
NA |
|
128.1 ± 28 |
8.1 ± 4 |
|
17.1 ± 8 |
0.86 ± 0.2 |
9.4 |
4.9 ± 2 |
|
| 20 | 45.8 ± 9 | 2.3 ± 0.7 | 98.1 ± 11 | 7.5 ± 3 | 13.1 ± 6 | 0.845 ± 0.2 | 8.9 | 2.9 ± 1 |
N, nitrogen; P, phosphorus; NA (not analyzed).