Valorization of Palm Oil Mill Effluent into Biodiesel Using Mixed Whole-cell Candida albicans and Pseudomonas aeruginosa

Abstract

The indiscriminate discharge of raw palm oil mill effluent (POME) severely pollutes the environment. POME is generated in large quantities in many parts of Imo State, Nigeria, where the processing of palm fruits is a major occupation. However, there is crisis in the global energy supply which necessitates the investigation of diverse renewable, non-food sources for energy sufficiency. The aim of this study was to investigate the potential of valorizing POME samples from parts of Imo State, Nigeria, into biodiesel using autochthonous Candida albicans and Pseudomonas aeruginosa consortium as whole-cell biocatalysts. POME samples were collected from parts of Imo State. The physicochemical and microbial properties of the mixed sample were evaluated. Identified C. albicans and P. aeruginosa consortium was applied as whole-cell biocatalysts for biodiesel production. Biodiesel was produced at 28±2 oC, 250 rpm, 1:4 molar ratio of POME:ethanol, pH 7, water content of 15 %wt. and 30% v/v of 0.5 McFarland standardized 1:1 co-culture of C. albicans and P. aeruginosa for 36 h. The properties of the resulting biodiesel were determined and compared to known standards. The mixed POME sample had pH, acid, free fatty acid and saponification values of 3.68±0.40, 22.31±3.51 mg KOH/g, 62.69±10.12 mg KOH/g and 125.06±3.46 mg/g, respectively. The lipolytic activity showed that lipases from Pseudomonas spp. and Candida spp. had 5.50±1.1 mm and 3.00±0.7 mm clearance zones. The percentage biodiesel yield was 40.00±0.76%. The produced biodiesel showed acceptable acid value, cetane rating, and viscosity (at 40 °C) of 0.54 mg KOH/g, 51 and 2.6 mm²/s, respectively, but a low flash point of 75 °C. Consequently, with process optimization, the POME generated in palm oil mills in Imo State, Nigeria, is feasible for biodiesel production using autochthonous whole-cell biocatalysts.