Table 1.
Twelve-trials Plackett–Burman experimental design for evaluation of independent variables with coded and actual levels along with the observed and predicted values of cadmium removal by Ulva fasciata.
| Run no. | Coded and actual levels of independent variables | Cadmium removal (%) | Residuals | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Contact time (min.) | Cadmium conc. (mg/L) | pH | Temperature (°C) | Biomass (g/L) | Agitation -Static | Actual value | Predicted value | ||||||||
| 1 | −1 | 60 | −1 | 25 | −1 | 4 | 1 | 50 | 1 | 4 | 1 | Agitation | 92.3 | 92.789 | −0.489 |
| 2 | −1 | 60 | −1 | 25 | 1 | 7 | 1 | 50 | 1 | 4 | −1 | Static | 94.66 | 93.763 | 0.898 |
| 3 | −1 | 60 | 1 | 200 | 1 | 7 | 1 | 50 | −1 | 1 | 1 | Agitation | 99.14 | 99.104 | 0.036 |
| 4 | 1 | 180 | −1 | 25 | 1 | 7 | 1 | 50 | −1 | 1 | 1 | Agitation | 91.5 | 91.944 | −0.444 |
| 5 | 1 | 180 | −1 | 25 | −1 | 4 | −1 | 25 | 1 | 4 | 1 | Agitation | 91.65 | 91.526 | 0.124 |
| 6 | −1 | 60 | 1 | 200 | −1 | 4 | −1 | 25 | −1 | 1 | 1 | Agitation | 97.9 | 97.431 | 0.469 |
| 7 | 1 | 180 | 1 | 200 | −1 | 4 | 1 | 50 | −1 | 1 | −1 | Static | 97.5 | 97.473 | 0.028 |
| 8 | 1 | 180 | 1 | 200 | 1 | 7 | −1 | 25 | 1 | 4 | 1 | Agitation | 99.4 | 99.096 | 0.304 |
| 9 | −1 | 60 | −1 | 25 | −1 | 4 | −1 | 25 | −1 | 1 | −1 | Static | 90.73 | 90.834 | −0.104 |
| 10 | 1 | 180 | −1 | 25 | 1 | 7 | −1 | 25 | −1 | 1 | −1 | Static | 91.26 | 91.244 | 0.016 |
| 11 | 1 | 180 | 1 | 200 | −1 | 4 | 1 | 50 | 1 | 4 | −1 | Static | 98.7 | 98.728 | −0.027 |
| 12 | −1 | 60 | 1 | 200 | 1 | 7 | −1 | 25 | 1 | 4 | −1 | Static | 98.85 | 99.659 | −0.809 |
The −1 sign correspond to the minimum value and the +1 sign correspond to the maximum value of the input parameter range.