DOE CASE STUDY 2
In a waste water treatment facility, a combination of coagulant chemicals, treatment temperature and stirring speed were identified as a critical factor to treat the waste-water to produce clean water. The clean water produced is recycled back into the main proses and at the same time reduce the amount of pollutant discharged by the plant.
8 runs were performed and the data are shown below.
The response variable (y) is the amount of pollutant discharged (lb/day)
A = concentration of coagulant added, 1% and 2% by weight
B = treatment temperature, 72oC and 100oF
C = Stirring speed, 200 rpm and 400 rpm
FULL factorial
Factor C, Stirring speed, is the most significant factor that affects the amount of pollution discharged (lb/day).
Factor B, treatment temperature, is the second most significant factor that affects the amount of pollution discharged (lb/day).
Factor A, concentration of coagulant added, is the least significant factor that affects the amount of pollution discharged (lb/day).
The gradient of both lines is different by a little margin. Therefore there’s an interaction between A and B, but the interaction is small. If both lines are parallel, then there’s NO interaction
The gradient of both lines are different (one is + and the other is -). Therefore there’s a significant interaction between A and C
The gradient of both lines is different by a large margin. Both lines are parallel, there’s NO interaction.
Conclusion:
Factor C, Stirring speed, is the most significant factor that affects the amount of pollution discharged (lb/day). Also, there’s a significant interaction between A and C.
FRACTIONAL factorial
Factor C, Stirring speed, is the most significant factor that affects the amount of pollution discharged (lb/day).
Factor A, concentration of coagulant added, is the second most significant factor that affects the amount of pollution discharged (lb/day).
Factor B, treatment temperature, is the least significant factor that affects the amount of pollution discharged (lb/day).
The gradient of both lines are different (one is + and the other is -). Therefore there’s a significant interaction between A and B.
The gradient of both lines are different (one is + and the other is -). Therefore there’s a significant interaction between A and C.
Factor C, Stirring speed, is the most significant factor that affects the amount of pollution discharged (lb/day). There’s a significant interaction between A and B. Also, there’s a significant interaction between A and C.
