Table 4 ANOVA results of quadratic for COD, colour, turbidity, and TOC removals.

From: Domestic greywater treatment using electrocoagulation-electrooxidation process: optimisation and experimental approaches

Source of variations

Sum of square

Degree of freedom

Mean square

F-value

P-value pro. > F

RCOD

RColour

RTurbidity

RTOC

RCOD

RColour

RTurbidity

RTOC

RCOD

RColour

RTurbidity

RTOC

RCOD

RColour

RTurbidity

RTOC

RCOD

RColour

RTurbidity

RTOC

Model

1164.61

982.53

2249.44

869.20

14

14

14

14

83.19

70.18

160.67

62.09

61.00

104.65

78.17

55.97

 < 0.0001*

 < 0.0001*

 < 0.0001*

 < 0.0001*

A-current density

96.52

723.03

0.07

217.08

1

1

1

1

96.52

723.03

0.07

217.08

70.78

1078.16

0.034

195.70

 < 0.0001*

 < 0.0001*

0.8558

 < 0.0001*

B-pH

17.05

3.07

1989.62

258.60

1

1

1

1

17.05

3.07

1989.62

258.60

12.50

4.58

967.98

233.12

0.0033^

0.0503

 < 0.0001*

 < 0.0001*

C- EC time

11.97

13.22

3.50

0.09

1

1

1

1

11.97

13.22

3.50

0.097

8.78

19.71

1.70

0.09

0.0103^

0.0006^

0.2132

0.7726

D- EO time

96.28

24.42

4.40

96.40

1

1

1

1

96.28

24.42

4.40

96.40

70.60

36.42

2.14

86.91

 < 0.0001*

 < 0.0001*

0.1654

 < 0.0001*

AB

83.31

4.25

1.80

23.38

1

1

1

1

83.31

4.25

1.80

23.38

61.09

6.34

0.87

2.14

 < 0.0001*

0.0246^

0.3658

0.0004^

AC

1.36

0.07

12.08

4.18

1

1

1

1

1.36

0.07

12.08

4.18

0.99

0.10

5.87

0.87

0.3344

0.7488

0.0295^

0.0726

AD

68.93

7.66

0.67

0.03

1

1

1

1

68.93

7.66

0.67

0.03

50.55

11.42

0.33

5.87

 < 0.0001*

0.0045^

0.5764

0.8631

BC

12.69

21.14

6.68

1.27

1

1

1

1

12.69

21.14

6.68

1.27

9.31

31.52

3.25

0.32

0.0086^

 < 0.0001*

0.0929

0.3035

BD

23.30

4.03

5.48

7.54

1

1

1

1

23.30

4.03

5.48

7.54

17.09

6.01

2.66

3.25

0.0010^

0.0280^

0.1249

0.0207^

CD

95.01

0.35

0.12

0.47

1

1

1

1

95.01

0.35

0.12

0.47

69.67

0.52

0.058

2.66

 < 0.0001*

0.4813

0.8133

0.5260

A2

16.35

175.66

14.51

3.95

1

1

1

1

16.35

175.66

14.51

3.95

0.04

261.93

7.06

0.06

0.0038^

 < 0.0001*

0.0188^

0.0801

B2

534.75

4.17

217.32

250.97

1

1

1

1

534.75

4.17

217.32

250.97

392.13

6.21

105.73

7.06

 < 0.0001*

0.0258^

 < 0.0001*

 < 0.0001*

C2

1.54

4.30

17.04

16.97

1

1

1

1

1.54

4.30

17.04

16.97

1.13

6.41

8.29

105.73

0.3060

0.0240^

0.0121^

0.0016^

D2

14.12

0.03

28.01

0.34

1

1

1

1

14.12

0.03

28.01

0.34

10.35

0.04

13.63

8.29

0.0062^

0.8275

0.0024^

0.5866

Residual

19.09

0.03

28.78

15.53

14

14

14

14

1.36

0.67

2.06

1.11

        

Lack of fit

16.78

7.93

23.59

13.53

10

10

10

10

1.68

0.79

2.36

1.35

2.91

0.79

1.82

13.63

0.1577

0.2356

0.2959

0.1745

Pure error

2.31

1.46

5.18

2.00

4

4

4

4

0.58

0.36

1.30

0.49

 

0.36

      

Cor Total

1183.70

991.92

2278.21

884.73

28

28

28

28

            

RCOD

R2/R2adj (%) = 0.98/0.97

C.V. % = 1.28

              

RColour

R2/R2adj (%) = 0.94/0.95

C.V. % = 0.88

              

RTurbidity

R2/R2adj (%) = 0.94/0.88

C.V. % = 1.15

              

RTOC

R2/R2adj (%) = 0.98/0.96

C.V. % = 1.61

              
  1. *Highly significant, ^Significant.
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