Plackett-Burman and Response Surface Methodology for Optimization of Oily Wastewater Bioremediation by Aspergillus sp.

Abstract

Plackett-Burman is beneficial design not only in determining the significant variables of bioremediation, but also in optimization of these variables. In this study, Plackett-Burman (PB) experimental model had been applied to assess the significant of some nutritional and environmental condition affecting oily wastewater bioremediation by Aspergillus niger. Eleven variables through twelve assays were planned, namely; Temperature, pH, sucrose, KH2PO4, NaCl, MgSO4, Na2HPO4, NH4Cl, NaNO3, urea and spore suspension to explain their effects on remediation of water contaminated with oil. The degradation process was enhanced based on oil and grease experiment. pH, sucrose, KH2PO4, NaCl, Na2HPO4 and urea were recognized as the positive factors that stimulate the degradation. On the other hand, other variables affected negatively on remediation process. The regression coefficient (R2 = 0.99) ensure the adequate integrity of the model. It was showed that sucrose (A), NaCl (B) and KH2PO4 (C) give high removal of oily wastewater when approaching to +1, on the other hand, the temperature (D) give high removal of oily wastewater when approaching to -1. (B) had positive effects on oily wastewater degradation, whereas C and D had negative effects. The factor with confidence level above 95% is considered as significant parameter. It was clear that variable B was the chief factor, while variables A, C, D, with levels below 95%, were considered insignificant.