Oil and grease treatment using indigenous bacterial biofilm system

Abstract

The Malaysian palm oil industry grows rapidly as the premier agriculture based industry over the last two decades. However, the production of palm oil also resulted in the generation of large quantities of polluted wastewater commonly referred to as palm oil mill effluent (POME) as well as lignocellulosic biomass, especially from fronds, trunks, empty fruit bunch, palm kernel and mesocarp fibre. This study evaluates on the potential application of an immobilized bacterial-based system to reduce oil and grease (O&G) contamination in POME. From the 21 bacterial isolates, two isolates (i.e. isolate X7 and X10) were chosen for subsequent studies based on its high cell surface hydrophobicity, opaque halo formation and high culture turbidity. The bacterial isolates were evaluated for O&G degradation ability by varying contact time, initial POME concentration and initial pH. The isolated X10 showed the ability to completely degrade O&G from POME after 6 days of incubation at 200 rpm, 30oC and pH 7 in the batch study. In the continuous flowthrough column study, oil palm frond (OPF) - immobilized isolate X7 showed complete O&G degradation and 92.59% of chemical oxygen demand (COD) degradation from 100% (v/v) POME used after 8 days of contact time. Scanning Electron Microscope examination showed the presence of diverse morphology of microorganisms indicating the formation of mature biofilm after 200 days. One of the bacterial species isolated from the biofilm was identified as Bacillus cereus in which match up to 99% of the query sequence. The finding of this study indicates the potential of using indigenous aerobic bacterial isolates as an alternative solution to degrade O&G in POME wastewaters.