Table 2.

Summary polynomial models for gas and methane production from date fruit, rice waste, legume beans, and food waste samples.

	Model	Adjusted R2	P-value
Biogas production models
Date fruit	Y = − 50.9 + 230X − 36.6X2 + 2.3X3 − 0.04X4	0.99	< 0.0001
Rice waste	Y = − 72 + 308x − 49x2 + 3.19X3 − 0.06X4	0.99	< 0.0001
Legume beans	Y = − 56.29 + 232.9x − 37x2 + 2.3x3 0.04x4	0.99	< 0.0001
Food waste	Y = − 86 + 229.5x − 36x2 + 2.1x3 − 0.03x4	0.99	< 0.0001
Methane production models
Date fruit	Y = − 135.8 + 191x − 31x2 + 1.8x3 − 0.036x4	0.94	0.042
Rice waste	Y = 110–54.5x + 23x2 − 2.4x3 + 0.07x4	0.55	0.29
Legume beans	Y = − 3.9 + 112.9x − 22.6x2 + 1.63x3 − 0.04x4	0.36	0.37
Food waste	Y = − 22.7 + 67x − 9.9x2 − 0.54x3 − 0.008x4	0.91	0.059