Optimization to Hydrothermal Liquefaction of Low Lipid Content Microalgae Spirulina sp. Using Response Surface Methodology

Table 2

Experimental factors and the levels.

Factors	Encoding of the variables () and level
	−1.682	−1	0	1	1.682
concentration (%)	7.5	9.5	12.5	15.5	17.5
temperature (°C)	315	327	345	363	375
time (min)	20	28	40	52	60