Parameter P1 P2 Optimum Condition Time (day) 0.583 0.583 20 Salt (g) 0.452 0.000 0.0 Activated sludge (ml) 0.850 0.850 0.0 Bacteria (ml) 89.743 89.743 0.04 Composting (g) 0.000 0.000 0.05 Molasses (g) 2.562 2.546 0.1 Humidity (ml) 2.228 2.228 1.0 Urea (g) 2.037 2.037 0.01 Other error    1.545 1.997 ----- Oil removal percent in optimum conditions 68%

Table 8: The effect percent of each factor (P1), effect percent of more important parameters (P2) and optimum conditions for set 2, determined by the analysis of variance (ANOVA).