Biodegradation of fresh palm oil mill effluent and fungal biomass protein recovery by aspergillus niger and trichoderma virens

Abstract

This study was conducted to evaluate the potential of filamentous fungi for fresh palm oil mill effluent (POME) biodegradation. Two strains of filamentous fungi namely Aspergillus niger and Trichoderma virens were utilized and their performance in fresh POME biodegradation were studied and compared. The results of preliminary study showed that A. niger demonstrated high capacity in enhancing the biodegradation process of fresh POME in terms of reduction of total suspended solids (TSS) (340 mg/l), turbidity (110 NTU) and chemical oxygen demand (COD) (3200 mg/l) than T. virens (TSS: 720 mg/l; turbidity: 224 NTU; COD: 3520 mg/l). Additionally, considerable amount of biosolids enriched with fungal biomass corresponding to higher protein yield was achieved in fungal treated fresh POME as greater amount was obtained in fresh POME treated by A. niger (13.9 g/l/3.09 g/l) as compared to T. virens (9.95 g/l/2.33 g/l). Effects of inoculum size (%), agitation rate (rpm) and temperature (oC) on the biodegradation process of the fresh POME by both fungal strains were examined using response surface methodology (RSM). Fresh POME treated by A. niger was more predictable compared to T. virens as high reduction of TSS and specific resistance to filtration (SRF) with greater recovery of biosolids enriched with fungal biomass (50.40 g/l) and protein (12.9 g/l) were achieved at optimal operating conditions. Monod kinetic model was utilized to define the biodegradation kinetic of fresh POME by both strains. High maximum specific growth rate (µmax) (0.81 h -1) revealed in fresh POME treated by A. niger thus signify that A. niger has the fastest growth rate and thus would be most effective in reducing the pollutant levels of fresh POME compared to T. virens (0.009 h-1)