Simultaneous dephenolization and decolorization of treated palm oil mill effluent by oil palm fiber-immobilized Trametes hirsuta strain AK 04.

The phenolics and high organic content present in palm oil mill effluent are the major contributors to its dark brown color, toxicity, and antimicrobial properties. In this study, ten white rot fungi were screened for their potential in the dephenolization and decolorization of treated palm oil mill effluent (TPOME) in solid and liquid state cultures. Among them, Trametes hirsuta strain AK 04 was found to be more tolerant to high TPOME concentrations and showed the highest phenolics and color removal activities. This strain was immobilized onto oil palm fibers (OPFs) and appeared more resistant to inhibitory compounds such as phenolics in TPOME than the free cell culture. The OPF-immobilized fungus was able to effectively remove phenolics and color of TPOME without effluent dilution and addition of nutrients. The activities of laccase and manganese peroxidase were found during dephenolization and decolorization processes. Moreover, the degradation rate of immobilized fungus could be accelerated by pretreatment of phenolics with phenol-degrading bacteria. This method improved the fungal dephenolization and decolorization simultaneously up to 82.2 ± 3.8 % and 87.1 ± 1.1 % after 8 days of incubation. Therefore, a two-stage biological process containing phenol-degrading bacteria and OPF-immobilized fungus could be a feasible and economical method for simultaneous improvement of dephenolization and decolorization of TPOME.